<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <link:roleRef roleURI="http://enphase.com/role/AccruedLiabilities" xlink:href="enph-20161231.xsd#AccruedLiabilities" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/AccruedLiabilitiesScheduleOfAccruedLiabilitiesDetails" xlink:href="enph-20161231.xsd#AccruedLiabilitiesScheduleOfAccruedLiabilitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/AccruedLiabilitiesTables" xlink:href="enph-20161231.xsd#AccruedLiabilitiesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/AcquisitionAndDivestureGoodwillAndIntangibleAssets" xlink:href="enph-20161231.xsd#AcquisitionAndDivestureGoodwillAndIntangibleAssets" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/AcquisitionAndDivestureGoodwillAndIntangibleAssetsNarrativeDetails" xlink:href="enph-20161231.xsd#AcquisitionAndDivestureGoodwillAndIntangibleAssetsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/AcquisitionAndDivestureGoodwillAndIntangibleAssetsScheduleOfEstimatedFutureAmortizationExpenseRelatedToFiniteLivedIntangibleAssetsDetails" xlink:href="enph-20161231.xsd#AcquisitionAndDivestureGoodwillAndIntangibleAssetsScheduleOfEstimatedFutureAmortizationExpenseRelatedToFiniteLivedIntangibleAssetsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/AcquisitionAndDivestureGoodwillAndIntangibleAssetsSummaryOfGoodwillAndPurchasedIntangibleAssetsDetails" xlink:href="enph-20161231.xsd#AcquisitionAndDivestureGoodwillAndIntangibleAssetsSummaryOfGoodwillAndPurchasedIntangibleAssetsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/AcquisitionAndDivestureGoodwillAndIntangibleAssetsTables" xlink:href="enph-20161231.xsd#AcquisitionAndDivestureGoodwillAndIntangibleAssetsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/CommitmentsAndContingencies" xlink:href="enph-20161231.xsd#CommitmentsAndContingencies" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/CommitmentsAndContingenciesNarrativeDetails" xlink:href="enph-20161231.xsd#CommitmentsAndContingenciesNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/CommitmentsAndContingenciesScheduleOfMinimumLeasePaymentsUnderNoncancelableOperatingLeasesDetails" xlink:href="enph-20161231.xsd#CommitmentsAndContingenciesScheduleOfMinimumLeasePaymentsUnderNoncancelableOperatingLeasesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/CommitmentsAndContingenciesTables" xlink:href="enph-20161231.xsd#CommitmentsAndContingenciesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/ConcentrationOfCreditRiskAndMajorCustomers" xlink:href="enph-20161231.xsd#ConcentrationOfCreditRiskAndMajorCustomers" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/ConcentrationOfCreditRiskAndMajorCustomersNarrativeDetails" xlink:href="enph-20161231.xsd#ConcentrationOfCreditRiskAndMajorCustomersNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/ConsolidatedBalanceSheets" xlink:href="enph-20161231.xsd#ConsolidatedBalanceSheets" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:href="enph-20161231.xsd#ConsolidatedBalanceSheetsParenthetical" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/ConsolidatedStatementsOfCashFlows" xlink:href="enph-20161231.xsd#ConsolidatedStatementsOfCashFlows" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/ConsolidatedStatementsOfComprehensiveLoss" xlink:href="enph-20161231.xsd#ConsolidatedStatementsOfComprehensiveLoss" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/ConsolidatedStatementsOfOperations" xlink:href="enph-20161231.xsd#ConsolidatedStatementsOfOperations" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/ConsolidatedStatementsOfStockholdersEquity" xlink:href="enph-20161231.xsd#ConsolidatedStatementsOfStockholdersEquity" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/Debt" xlink:href="enph-20161231.xsd#Debt" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/DebtLongTermDebtDetails" xlink:href="enph-20161231.xsd#DebtLongTermDebtDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/DebtMaturityScheduleDetails" xlink:href="enph-20161231.xsd#DebtMaturityScheduleDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/DebtRevolvingCreditFacilityDetails" xlink:href="enph-20161231.xsd#DebtRevolvingCreditFacilityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/DebtTables" xlink:href="enph-20161231.xsd#DebtTables" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/DebtTermLoanDetails" xlink:href="enph-20161231.xsd#DebtTermLoanDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/DescriptionOfBusiness" xlink:href="enph-20161231.xsd#DescriptionOfBusiness" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/DescriptionOfBusinessNarrativeDetails" xlink:href="enph-20161231.xsd#DescriptionOfBusinessNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/DocumentAndEntityInformation" xlink:href="enph-20161231.xsd#DocumentAndEntityInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/FairValueMeasurements" xlink:href="enph-20161231.xsd#FairValueMeasurements" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/FairValueMeasurementsNarrativeDetails" xlink:href="enph-20161231.xsd#FairValueMeasurementsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/FairValueMeasurementsScheduleOfFinancialInstrumentsMeasuredAtFairValueOnRecurringBasisDetails" xlink:href="enph-20161231.xsd#FairValueMeasurementsScheduleOfFinancialInstrumentsMeasuredAtFairValueOnRecurringBasisDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/FairValueMeasurementsScheduleOfReconciliationOfBeginningAndEndingBalancesOfWarrantyObligationsMeasuredAtFairValueDetails" xlink:href="enph-20161231.xsd#FairValueMeasurementsScheduleOfReconciliationOfBeginningAndEndingBalancesOfWarrantyObligationsMeasuredAtFairValueDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/FairValueMeasurementsSummaryOfSignificantUnobservableInputsUsedInFairValueMeasurementsOfCompanysLiabilitiesDesignatedAsLevel3Details" xlink:href="enph-20161231.xsd#FairValueMeasurementsSummaryOfSignificantUnobservableInputsUsedInFairValueMeasurementsOfCompanysLiabilitiesDesignatedAsLevel3Details" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/FairValueMeasurementsTables" xlink:href="enph-20161231.xsd#FairValueMeasurementsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/IncomeTaxes" xlink:href="enph-20161231.xsd#IncomeTaxes" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/IncomeTaxesNarrativeDetails" xlink:href="enph-20161231.xsd#IncomeTaxesNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/IncomeTaxesScheduleOfDeferredTaxAssetsAndLiabilitiesDetails" xlink:href="enph-20161231.xsd#IncomeTaxesScheduleOfDeferredTaxAssetsAndLiabilitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/IncomeTaxesScheduleOfDomesticAndForeignComponentsOfLossBeforeProvisionForIncomeTaxesDetails" xlink:href="enph-20161231.xsd#IncomeTaxesScheduleOfDomesticAndForeignComponentsOfLossBeforeProvisionForIncomeTaxesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/IncomeTaxesScheduleOfEffectiveIncomeTaxRateReconciliationDetails" xlink:href="enph-20161231.xsd#IncomeTaxesScheduleOfEffectiveIncomeTaxRateReconciliationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/IncomeTaxesScheduleOfProvisionForIncomeTaxesDetails" xlink:href="enph-20161231.xsd#IncomeTaxesScheduleOfProvisionForIncomeTaxesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/IncomeTaxesScheduleOfReconciliationOfTotalAmountsOfUnrecognizedTaxBenefitsDetails" xlink:href="enph-20161231.xsd#IncomeTaxesScheduleOfReconciliationOfTotalAmountsOfUnrecognizedTaxBenefitsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/IncomeTaxesTables" xlink:href="enph-20161231.xsd#IncomeTaxesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/Inventory" xlink:href="enph-20161231.xsd#Inventory" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/InventorySummaryOfInventoryDetails" xlink:href="enph-20161231.xsd#InventorySummaryOfInventoryDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/InventoryTables" xlink:href="enph-20161231.xsd#InventoryTables" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/NetLossPerShare" xlink:href="enph-20161231.xsd#NetLossPerShare" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/NetLossPerShareScheduleOfPotentialCommonSharesOutstandingExcludedFromComputationOfDilutedNetLossPerShareAttributableToCommonStockholdersDetails" xlink:href="enph-20161231.xsd#NetLossPerShareScheduleOfPotentialCommonSharesOutstandingExcludedFromComputationOfDilutedNetLossPerShareAttributableToCommonStockholdersDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/NetLossPerShareTables" xlink:href="enph-20161231.xsd#NetLossPerShareTables" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/PropertyAndEquipmentNet" xlink:href="enph-20161231.xsd#PropertyAndEquipmentNet" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/PropertyAndEquipmentNetNarrativeDetails" xlink:href="enph-20161231.xsd#PropertyAndEquipmentNetNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/PropertyAndEquipmentNetSummaryOfPropertyAndEquipmentDetails" xlink:href="enph-20161231.xsd#PropertyAndEquipmentNetSummaryOfPropertyAndEquipmentDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/PropertyAndEquipmentNetTables" xlink:href="enph-20161231.xsd#PropertyAndEquipmentNetTables" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/QuarterlyFinancialInformationUnaudited" xlink:href="enph-20161231.xsd#QuarterlyFinancialInformationUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/QuarterlyFinancialInformationUnauditedScheduleOfQuarterlyFinancialInformationDetails" xlink:href="enph-20161231.xsd#QuarterlyFinancialInformationUnauditedScheduleOfQuarterlyFinancialInformationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/QuarterlyFinancialInformationUnauditedTables" xlink:href="enph-20161231.xsd#QuarterlyFinancialInformationUnauditedTables" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/RestructuringAndOther" xlink:href="enph-20161231.xsd#RestructuringAndOther" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/RestructuringAndOtherDetails" xlink:href="enph-20161231.xsd#RestructuringAndOtherDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/RestructuringAndOtherRollforwardDetails" xlink:href="enph-20161231.xsd#RestructuringAndOtherRollforwardDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/RestructuringAndOtherScheduleRestructuringChargesDetails" xlink:href="enph-20161231.xsd#RestructuringAndOtherScheduleRestructuringChargesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/RestructuringAndOtherTables" xlink:href="enph-20161231.xsd#RestructuringAndOtherTables" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/SaleOfCommonStock" xlink:href="enph-20161231.xsd#SaleOfCommonStock" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/SaleOfCommonStockDetails" xlink:href="enph-20161231.xsd#SaleOfCommonStockDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/SegmentAndGeographicInformation" xlink:href="enph-20161231.xsd#SegmentAndGeographicInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/SegmentAndGeographicInformationNarrativeDetails" xlink:href="enph-20161231.xsd#SegmentAndGeographicInformationNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/SegmentAndGeographicInformationSummaryOfLongLivedAssetsByGeographicRegionDetails" xlink:href="enph-20161231.xsd#SegmentAndGeographicInformationSummaryOfLongLivedAssetsByGeographicRegionDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/SegmentAndGeographicInformationSummaryOfNetRevenuesByGeographicRegionDetails" xlink:href="enph-20161231.xsd#SegmentAndGeographicInformationSummaryOfNetRevenuesByGeographicRegionDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/SegmentAndGeographicInformationTables" xlink:href="enph-20161231.xsd#SegmentAndGeographicInformationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/StockBasedCompensation" xlink:href="enph-20161231.xsd#StockBasedCompensation" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/StockBasedCompensationNarrativeDetails" xlink:href="enph-20161231.xsd#StockBasedCompensationNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/StockBasedCompensationScheduleOfWeightedAverageAssumptionsUsedToEstimateFairValueOfStockOptionsGrantedDetails" xlink:href="enph-20161231.xsd#StockBasedCompensationScheduleOfWeightedAverageAssumptionsUsedToEstimateFairValueOfStockOptionsGrantedDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/StockBasedCompensationSummaryOfEsppActivityDetails" xlink:href="enph-20161231.xsd#StockBasedCompensationSummaryOfEsppActivityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/StockBasedCompensationSummaryOfRestrictedStockUnitActivityDetails" xlink:href="enph-20161231.xsd#StockBasedCompensationSummaryOfRestrictedStockUnitActivityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/StockBasedCompensationSummaryOfStockBasedCompensationExpenseAssociatedWithEachTypeOfAwardDetails" xlink:href="enph-20161231.xsd#StockBasedCompensationSummaryOfStockBasedCompensationExpenseAssociatedWithEachTypeOfAwardDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/StockBasedCompensationSummaryOfStockOptionActivityDetails" xlink:href="enph-20161231.xsd#StockBasedCompensationSummaryOfStockOptionActivityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/StockBasedCompensationSummaryOfStockOptionsOutstandingDetails" xlink:href="enph-20161231.xsd#StockBasedCompensationSummaryOfStockOptionsOutstandingDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/StockBasedCompensationSummaryOfTotalStockBasedCompensationExpenseComponentsDetails" xlink:href="enph-20161231.xsd#StockBasedCompensationSummaryOfTotalStockBasedCompensationExpenseComponentsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/StockBasedCompensationTables" xlink:href="enph-20161231.xsd#StockBasedCompensationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/SubsequentEvent" xlink:href="enph-20161231.xsd#SubsequentEvent" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/SubsequentEventDetails" xlink:href="enph-20161231.xsd#SubsequentEventDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/SummaryOfSignificantAccountingPolicies" xlink:href="enph-20161231.xsd#SummaryOfSignificantAccountingPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/SummaryOfSignificantAccountingPoliciesNarrativeDetails" xlink:href="enph-20161231.xsd#SummaryOfSignificantAccountingPoliciesNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:href="enph-20161231.xsd#SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/SummaryOfSignificantAccountingPoliciesScheduleOfActivityInAllowanceForDoubtfulAccountsDetails" xlink:href="enph-20161231.xsd#SummaryOfSignificantAccountingPoliciesScheduleOfActivityInAllowanceForDoubtfulAccountsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/SummaryOfSignificantAccountingPoliciesTables" xlink:href="enph-20161231.xsd#SummaryOfSignificantAccountingPoliciesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/WarrantyObligations" xlink:href="enph-20161231.xsd#WarrantyObligations" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/WarrantyObligationsNarrativeDetails" xlink:href="enph-20161231.xsd#WarrantyObligationsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/WarrantyObligationsSummaryOfWarrantyActivityDetails" xlink:href="enph-20161231.xsd#WarrantyObligationsSummaryOfWarrantyActivityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://enphase.com/role/WarrantyObligationsTables" xlink:href="enph-20161231.xsd#WarrantyObligationsTables" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <link:definitionLink xlink:role="http://enphase.com/role/AccruedLiabilities" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/AccruedLiabilitiesScheduleOfAccruedLiabilitiesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/AccruedLiabilitiesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/AcquisitionAndDivestureGoodwillAndIntangibleAssets" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/AcquisitionAndDivestureGoodwillAndIntangibleAssetsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_C30BD59FDAEF2D413CB891AFAB68974F" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8168A431CF03078042E491AFAB6711AB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_C30BD59FDAEF2D413CB891AFAB68974F" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8168A431CF03078042E491AFAB6711AB" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_3BC38B0C224F862A481691AFAB675C84" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8168A431CF03078042E491AFAB6711AB" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_3BC38B0C224F862A481691AFAB675C84" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_5F3DC4CE8F58B3A3C89891AFAB674C6A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_3BC38B0C224F862A481691AFAB675C84" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_5F3DC4CE8F58B3A3C89891AFAB674C6A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_5F3DC4CE8F58B3A3C89891AFAB674C6A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_3BC38B0C224F862A481691AFAB675C84" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_5F3DC4CE8F58B3A3C89891AFAB674C6A" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_NextPhaseSolarInc.Member" xlink:label="loc_enph_NextPhaseSolarInc.Member_40D1A65FB92E3064D1E391AFAB674C38" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_5F3DC4CE8F58B3A3C89891AFAB674C6A" xlink:to="loc_enph_NextPhaseSolarInc.Member_40D1A65FB92E3064D1E391AFAB674C38" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_92FD156041A03197A66591AFAB67430B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8168A431CF03078042E491AFAB6711AB" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_92FD156041A03197A66591AFAB67430B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_AB9EA4B9376967A29D1A91AFAB67ED64_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_92FD156041A03197A66591AFAB67430B" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_AB9EA4B9376967A29D1A91AFAB67ED64_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_AB9EA4B9376967A29D1A91AFAB67ED64" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_92FD156041A03197A66591AFAB67430B" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_AB9EA4B9376967A29D1A91AFAB67ED64" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_NextPhaseSolarInc.Member" xlink:label="loc_enph_NextPhaseSolarInc.Member_DB2C067E42940D15BE0C91AFAB676160" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_AB9EA4B9376967A29D1A91AFAB67ED64" xlink:to="loc_enph_NextPhaseSolarInc.Member_DB2C067E42940D15BE0C91AFAB676160" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_3624F3C6A2B2530C148391AFAB67AB8B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8168A431CF03078042E491AFAB6711AB" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_3624F3C6A2B2530C148391AFAB67AB8B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_FB25121478211035901191AFAB67A500_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_3624F3C6A2B2530C148391AFAB67AB8B" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_FB25121478211035901191AFAB67A500_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_FB25121478211035901191AFAB67A500" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_3624F3C6A2B2530C148391AFAB67AB8B" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_FB25121478211035901191AFAB67A500" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaap_CustomerRelationshipsMember_03F6593D98F37A48B1E591AFAB67F2CB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_FB25121478211035901191AFAB67A500" xlink:to="loc_us-gaap_CustomerRelationshipsMember_03F6593D98F37A48B1E591AFAB67F2CB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PatentsMember" xlink:label="loc_us-gaap_PatentsMember_581779888A8CF017073391AFAB67E668" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_FB25121478211035901191AFAB67A500" xlink:to="loc_us-gaap_PatentsMember_581779888A8CF017073391AFAB67E668" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductOrServiceAxis" xlink:label="loc_us-gaap_ProductOrServiceAxis_912943402E9ACE4C780091AFAB675A40" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8168A431CF03078042E491AFAB6711AB" xlink:to="loc_us-gaap_ProductOrServiceAxis_912943402E9ACE4C780091AFAB675A40" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductsAndServicesDomain" xlink:label="loc_us-gaap_ProductsAndServicesDomain_37B2E992B9B33229E24991AFAB676403_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ProductOrServiceAxis_912943402E9ACE4C780091AFAB675A40" xlink:to="loc_us-gaap_ProductsAndServicesDomain_37B2E992B9B33229E24991AFAB676403_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductsAndServicesDomain" xlink:label="loc_us-gaap_ProductsAndServicesDomain_37B2E992B9B33229E24991AFAB676403" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ProductOrServiceAxis_912943402E9ACE4C780091AFAB675A40" xlink:to="loc_us-gaap_ProductsAndServicesDomain_37B2E992B9B33229E24991AFAB676403" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_ApplicationSpecificIntegratedCircuitsMember" xlink:label="loc_enph_ApplicationSpecificIntegratedCircuitsMember_68B445DA00312BA363C491AFAB67E09F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductsAndServicesDomain_37B2E992B9B33229E24991AFAB676403" xlink:to="loc_enph_ApplicationSpecificIntegratedCircuitsMember_68B445DA00312BA363C491AFAB67E09F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferred1" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_5F8BAD88484EDF3206F991AFAB68C068" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_C30BD59FDAEF2D413CB891AFAB68974F" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_5F8BAD88484EDF3206F991AFAB68C068" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_10ED3C99569B32BCEEE791AFAB686EE8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_C30BD59FDAEF2D413CB891AFAB68974F" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_10ED3C99569B32BCEEE791AFAB686EE8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred_BA1F571A3C1FD2E7B8CD91AFAB68546C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_C30BD59FDAEF2D413CB891AFAB68974F" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred_BA1F571A3C1FD2E7B8CD91AFAB68546C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_3A15ADB2986E3E9D0BB391AFAB68393E" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_C30BD59FDAEF2D413CB891AFAB68974F" xlink:to="loc_us-gaap_Goodwill_3A15ADB2986E3E9D0BB391AFAB68393E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_02340573A85D502E156A91AFAB68D282" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_C30BD59FDAEF2D413CB891AFAB68974F" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_02340573A85D502E156A91AFAB68D282" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessCombinationIndemnificationAssetsAmountAsOfAcquisitionDate" xlink:label="loc_us-gaap_BusinessCombinationIndemnificationAssetsAmountAsOfAcquisitionDate_753F3BC015C094B58BF491AFAB68F6C3" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_C30BD59FDAEF2D413CB891AFAB68974F" xlink:to="loc_us-gaap_BusinessCombinationIndemnificationAssetsAmountAsOfAcquisitionDate_753F3BC015C094B58BF491AFAB68F6C3" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_BusinessCombinationContingentConsiderationLiabilityEarnOutPeriod" xlink:label="loc_enph_BusinessCombinationContingentConsiderationLiabilityEarnOutPeriod_343544E9C0502044A02691AFAB683FD0" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_C30BD59FDAEF2D413CB891AFAB68974F" xlink:to="loc_enph_BusinessCombinationContingentConsiderationLiabilityEarnOutPeriod_343544E9C0502044A02691AFAB683FD0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_3646E9A7EEE3A3284D5591AFAB68F1BC" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_C30BD59FDAEF2D413CB891AFAB68974F" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_3646E9A7EEE3A3284D5591AFAB68F1BC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GainLossOnSaleOfBusiness" xlink:label="loc_us-gaap_GainLossOnSaleOfBusiness_3AC2734EDA8A1928E6E391AFAB68734B" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_C30BD59FDAEF2D413CB891AFAB68974F" xlink:to="loc_us-gaap_GainLossOnSaleOfBusiness_3AC2734EDA8A1928E6E391AFAB68734B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_A7030E666D528BFEAC9491AFAB697C7D" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_C30BD59FDAEF2D413CB891AFAB68974F" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_A7030E666D528BFEAC9491AFAB697C7D" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_LicensedTechnologyTerm" xlink:label="loc_enph_LicensedTechnologyTerm_C4C8E115BC62508E75A091AFAB69F171" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_C30BD59FDAEF2D413CB891AFAB68974F" xlink:to="loc_enph_LicensedTechnologyTerm_C4C8E115BC62508E75A091AFAB69F171" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_3F6E271C99338B68C97091AFAB6948CE" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_C30BD59FDAEF2D413CB891AFAB68974F" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_3F6E271C99338B68C97091AFAB6948CE" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/AcquisitionAndDivestureGoodwillAndIntangibleAssetsScheduleOfEstimatedFutureAmortizationExpenseRelatedToFiniteLivedIntangibleAssetsDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/AcquisitionAndDivestureGoodwillAndIntangibleAssetsSummaryOfGoodwillAndPurchasedIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_4F48C975AE5AE8DC1A6A8BF9CE456CED" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4DF2ADC31A702FDAA3D38BF9CE4488F4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_4F48C975AE5AE8DC1A6A8BF9CE456CED" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4DF2ADC31A702FDAA3D38BF9CE4488F4" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_B452189CD70C9E072FB28BF9CE44EF99" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4DF2ADC31A702FDAA3D38BF9CE4488F4" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_B452189CD70C9E072FB28BF9CE44EF99" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_F1AA25648293A11C86E38BF9CE4486E8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_B452189CD70C9E072FB28BF9CE44EF99" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_F1AA25648293A11C86E38BF9CE4486E8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_F1AA25648293A11C86E38BF9CE4486E8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_B452189CD70C9E072FB28BF9CE44EF99" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_F1AA25648293A11C86E38BF9CE4486E8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaap_CustomerRelationshipsMember_EB301C76C4EC7BBA989D8BF9CE44FD1D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_F1AA25648293A11C86E38BF9CE4486E8" xlink:to="loc_us-gaap_CustomerRelationshipsMember_EB301C76C4EC7BBA989D8BF9CE44FD1D" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_PatentsAndLicensedTechnologyMember" xlink:label="loc_enph_PatentsAndLicensedTechnologyMember_78A2974AE83E3DA7D33B8BF9CE44C0EF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_F1AA25648293A11C86E38BF9CE4486E8" xlink:to="loc_enph_PatentsAndLicensedTechnologyMember_78A2974AE83E3DA7D33B8BF9CE44C0EF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillGross" xlink:label="loc_us-gaap_GoodwillGross_6AFDB5AA93953AC9383E8BF9CE45D94F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_4F48C975AE5AE8DC1A6A8BF9CE456CED" xlink:to="loc_us-gaap_GoodwillGross_6AFDB5AA93953AC9383E8BF9CE45D94F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_95CA1B7D1FCE34E323498BF9CE45DE15" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_4F48C975AE5AE8DC1A6A8BF9CE456CED" xlink:to="loc_us-gaap_Goodwill_95CA1B7D1FCE34E323498BF9CE45DE15" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_EFCBBF5D327C41E06EC78BF9CE45537D" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_4F48C975AE5AE8DC1A6A8BF9CE456CED" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_EFCBBF5D327C41E06EC78BF9CE45537D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNetAbstract" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_AB963E5C62F2DD5151A38BF9CE45C111" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_4F48C975AE5AE8DC1A6A8BF9CE456CED" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_AB963E5C62F2DD5151A38BF9CE45C111" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_B07067877E9AA37A1F888BF9CE45D24C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_AB963E5C62F2DD5151A38BF9CE45C111" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_B07067877E9AA37A1F888BF9CE45D24C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_C99DC6807748D1A651EF8BF9CE451EF6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_AB963E5C62F2DD5151A38BF9CE45C111" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_C99DC6807748D1A651EF8BF9CE451EF6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_604A94F36333B2BD58178BF9CE459519" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_AB963E5C62F2DD5151A38BF9CE45C111" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_604A94F36333B2BD58178BF9CE459519" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IntangibleAssetsGrossExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_16CC24321E9E39829D6E8BF9CE453095" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_4F48C975AE5AE8DC1A6A8BF9CE456CED" xlink:to="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_16CC24321E9E39829D6E8BF9CE453095" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_IntangibleAssetsAccumulatedAmortization" xlink:label="loc_enph_IntangibleAssetsAccumulatedAmortization_FB3D7989D19E43C3CBA38BF9CE4575EF" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_4F48C975AE5AE8DC1A6A8BF9CE456CED" xlink:to="loc_enph_IntangibleAssetsAccumulatedAmortization_FB3D7989D19E43C3CBA38BF9CE4575EF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_E87434E1EDC384AECE118BF9CE455FC9" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_4F48C975AE5AE8DC1A6A8BF9CE456CED" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_E87434E1EDC384AECE118BF9CE455FC9" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/AcquisitionAndDivestureGoodwillAndIntangibleAssetsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/CommitmentsAndContingencies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/CommitmentsAndContingenciesNarrativeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/CommitmentsAndContingenciesScheduleOfMinimumLeasePaymentsUnderNoncancelableOperatingLeasesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/CommitmentsAndContingenciesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/ConcentrationOfCreditRiskAndMajorCustomers" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/ConcentrationOfCreditRiskAndMajorCustomersNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EntityWideRevenueMajorCustomerLineItems" xlink:label="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_A8651E275F725F0267EB91AFA94B4085" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable" xlink:label="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_223B49D9A48F92D02A6D91AFA94ADF9A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_A8651E275F725F0267EB91AFA94B4085" xlink:to="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_223B49D9A48F92D02A6D91AFA94ADF9A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorCustomersAxis" xlink:label="loc_us-gaap_MajorCustomersAxis_7A5E7BD4E98361DC389791AFA94AAFD8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_223B49D9A48F92D02A6D91AFA94ADF9A" xlink:to="loc_us-gaap_MajorCustomersAxis_7A5E7BD4E98361DC389791AFA94AAFD8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NameOfMajorCustomerDomain" xlink:label="loc_us-gaap_NameOfMajorCustomerDomain_0552520FC1BC72B2DD9D91AFA94A7B8A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorCustomersAxis_7A5E7BD4E98361DC389791AFA94AAFD8" xlink:to="loc_us-gaap_NameOfMajorCustomerDomain_0552520FC1BC72B2DD9D91AFA94A7B8A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NameOfMajorCustomerDomain" xlink:label="loc_us-gaap_NameOfMajorCustomerDomain_0552520FC1BC72B2DD9D91AFA94A7B8A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorCustomersAxis_7A5E7BD4E98361DC389791AFA94AAFD8" xlink:to="loc_us-gaap_NameOfMajorCustomerDomain_0552520FC1BC72B2DD9D91AFA94A7B8A" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_CustomerAccountingForTheLargestConcentrationOfAccountsPayableMember" xlink:label="loc_enph_CustomerAccountingForTheLargestConcentrationOfAccountsPayableMember_53D64BF2EB77BC21530991AFA94A8E8A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NameOfMajorCustomerDomain_0552520FC1BC72B2DD9D91AFA94A7B8A" xlink:to="loc_enph_CustomerAccountingForTheLargestConcentrationOfAccountsPayableMember_53D64BF2EB77BC21530991AFA94A8E8A" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_LargestCustomerAccountingForMostRevenueMember" xlink:label="loc_enph_LargestCustomerAccountingForMostRevenueMember_45C6C9798590F565D06391AFA94A3E79" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NameOfMajorCustomerDomain_0552520FC1BC72B2DD9D91AFA94A7B8A" xlink:to="loc_enph_LargestCustomerAccountingForMostRevenueMember_45C6C9798590F565D06391AFA94A3E79" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_SecondLargestCustomerAccountingForMostRevenueMember" xlink:label="loc_enph_SecondLargestCustomerAccountingForMostRevenueMember_20BA14657D6E3D4A0CA291AFA94AD9BC" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NameOfMajorCustomerDomain_0552520FC1BC72B2DD9D91AFA94A7B8A" xlink:to="loc_enph_SecondLargestCustomerAccountingForMostRevenueMember_20BA14657D6E3D4A0CA291AFA94AD9BC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_3E147A389504AF9BCE4791AFA94AE890" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_223B49D9A48F92D02A6D91AFA94ADF9A" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_3E147A389504AF9BCE4791AFA94AE890" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_F865A6B58E1F866D864191AFA94AD173_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_3E147A389504AF9BCE4791AFA94AE890" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_F865A6B58E1F866D864191AFA94AD173_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_F865A6B58E1F866D864191AFA94AD173" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_3E147A389504AF9BCE4791AFA94AE890" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_F865A6B58E1F866D864191AFA94AD173" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsReceivableMember" xlink:label="loc_us-gaap_AccountsReceivableMember_81BAFAA3CD83593460FA91AFA94A88A8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_F865A6B58E1F866D864191AFA94AD173" xlink:to="loc_us-gaap_AccountsReceivableMember_81BAFAA3CD83593460FA91AFA94A88A8" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_NetRevenueMember" xlink:label="loc_enph_NetRevenueMember_9B4BDB9B492DC3D9B53291AFA94A9A1F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_F865A6B58E1F866D864191AFA94AD173" xlink:to="loc_enph_NetRevenueMember_9B4BDB9B492DC3D9B53291AFA94A9A1F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_3121EC1F50CD8410E2BD91AFA94AB8FB" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_223B49D9A48F92D02A6D91AFA94ADF9A" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_3121EC1F50CD8410E2BD91AFA94AB8FB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_2AA3F368B7DCD844BCF291AFA94A13F5_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_3121EC1F50CD8410E2BD91AFA94AB8FB" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_2AA3F368B7DCD844BCF291AFA94A13F5_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_2AA3F368B7DCD844BCF291AFA94A13F5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_3121EC1F50CD8410E2BD91AFA94AB8FB" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_2AA3F368B7DCD844BCF291AFA94A13F5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CreditConcentrationRiskMember" xlink:label="loc_us-gaap_CreditConcentrationRiskMember_6825101F1B12AC2EA94891AFA94A3188" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_2AA3F368B7DCD844BCF291AFA94A13F5" xlink:to="loc_us-gaap_CreditConcentrationRiskMember_6825101F1B12AC2EA94891AFA94A3188" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CustomerConcentrationRiskMember" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_9BD3328621D1C1E7FD0591AFA94AD6A6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_2AA3F368B7DCD844BCF291AFA94A13F5" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_9BD3328621D1C1E7FD0591AFA94AD6A6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_2F5605DE8ACADFAAB15891AFA94B1A13" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_A8651E275F725F0267EB91AFA94B4085" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_2F5605DE8ACADFAAB15891AFA94B1A13" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/ConsolidatedBalanceSheets" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/ConsolidatedStatementsOfCashFlows" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/ConsolidatedStatementsOfComprehensiveLoss" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/ConsolidatedStatementsOfOperations" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/ConsolidatedStatementsOfStockholdersEquity" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_AD01BD0A02EC66A4C9888FCF65588A45" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_FDA9C527B4E4F92E08CB8FCF65580782" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_AD01BD0A02EC66A4C9888FCF65588A45" xlink:to="loc_us-gaap_StatementTable_FDA9C527B4E4F92E08CB8FCF65580782" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_72FB04B618A8E57E32278FCF6558A7A9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_FDA9C527B4E4F92E08CB8FCF65580782" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_72FB04B618A8E57E32278FCF6558A7A9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_73900A247E11ACF9A8D38FCF65587FDC_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_72FB04B618A8E57E32278FCF6558A7A9" xlink:to="loc_us-gaap_EquityComponentDomain_73900A247E11ACF9A8D38FCF65587FDC_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_73900A247E11ACF9A8D38FCF65587FDC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_72FB04B618A8E57E32278FCF6558A7A9" xlink:to="loc_us-gaap_EquityComponentDomain_73900A247E11ACF9A8D38FCF65587FDC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_0F97C4154CF8ABF4F6E08FCF65582530" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_73900A247E11ACF9A8D38FCF65587FDC" xlink:to="loc_us-gaap_CommonStockMember_0F97C4154CF8ABF4F6E08FCF65582530" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_96C8C7A36A3FC49DFC538FCF6558E078" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_73900A247E11ACF9A8D38FCF65587FDC" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_96C8C7A36A3FC49DFC538FCF6558E078" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember_C7E33D8360873D1111038FCF6558F0F3" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_73900A247E11ACF9A8D38FCF65587FDC" xlink:to="loc_us-gaap_RetainedEarningsMember_C7E33D8360873D1111038FCF6558F0F3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_F843882412693B8EF9328FCF65586169" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_73900A247E11ACF9A8D38FCF65587FDC" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_F843882412693B8EF9328FCF65586169" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7285C9A6C333E8DE4BB28FCF65583A0D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_AD01BD0A02EC66A4C9888FCF65588A45" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7285C9A6C333E8DE4BB28FCF65583A0D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_27B856D44543C6040B158FCF65581EE2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7285C9A6C333E8DE4BB28FCF65583A0D" xlink:to="loc_us-gaap_StockholdersEquity_27B856D44543C6040B158FCF65581EE2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SharesOutstanding" xlink:label="loc_us-gaap_SharesOutstanding_2342884E4D9569B118378FCF6558C6BA" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7285C9A6C333E8DE4BB28FCF65583A0D" xlink:to="loc_us-gaap_SharesOutstanding_2342884E4D9569B118378FCF6558C6BA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_830244401DE2E261E4118FCF6558CB6C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7285C9A6C333E8DE4BB28FCF65583A0D" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_830244401DE2E261E4118FCF6558CB6C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_E98390661F8C83C7AE328FCF6558B77E" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7285C9A6C333E8DE4BB28FCF65583A0D" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_E98390661F8C83C7AE328FCF6558B77E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_8A528269EA0F9B1000678FCF6558E899" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7285C9A6C333E8DE4BB28FCF65583A0D" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_8A528269EA0F9B1000678FCF6558E899" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_CBF501BBD85EC70BEC618FCF6558443F" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7285C9A6C333E8DE4BB28FCF65583A0D" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_CBF501BBD85EC70BEC618FCF6558443F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_69408F9C60EDDE56854C8FCF65590E6F" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7285C9A6C333E8DE4BB28FCF65583A0D" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_69408F9C60EDDE56854C8FCF65590E6F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_E6EDD6152BF4525DF5828FCF6559A609" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7285C9A6C333E8DE4BB28FCF65583A0D" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_E6EDD6152BF4525DF5828FCF6559A609" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_F1A456BE11D4F800C6308FCF655914EB" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7285C9A6C333E8DE4BB28FCF65583A0D" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_F1A456BE11D4F800C6308FCF655914EB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_16A100FA4A84922902878FCF6559278B" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7285C9A6C333E8DE4BB28FCF65583A0D" xlink:to="loc_us-gaap_NetIncomeLoss_16A100FA4A84922902878FCF6559278B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax_A696212FC7E31E6F45FF8FCF655988BD" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7285C9A6C333E8DE4BB28FCF65583A0D" xlink:to="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax_A696212FC7E31E6F45FF8FCF655988BD" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/Debt" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/DebtLongTermDebtDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/DebtMaturityScheduleDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/DebtRevolvingCreditFacilityDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_FEB7DE4F249E7879866D836F7B4C3CF2" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_4C74219CFA08A2E87788836F7B4AF81F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_FEB7DE4F249E7879866D836F7B4C3CF2" xlink:to="loc_us-gaap_DebtInstrumentTable_4C74219CFA08A2E87788836F7B4AF81F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_F838D4CA3D2DB02E49F8836F7B4A6EB7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4C74219CFA08A2E87788836F7B4AF81F" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_F838D4CA3D2DB02E49F8836F7B4A6EB7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_0922540BD177CB9BDA41836F7B4A3150_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_F838D4CA3D2DB02E49F8836F7B4A6EB7" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_0922540BD177CB9BDA41836F7B4A3150_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_0922540BD177CB9BDA41836F7B4A3150" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_F838D4CA3D2DB02E49F8836F7B4A6EB7" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_0922540BD177CB9BDA41836F7B4A3150" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditMember" xlink:label="loc_us-gaap_LineOfCreditMember_0E4FAE99711B9DA122EE836F7B4A9431" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_0922540BD177CB9BDA41836F7B4A3150" xlink:to="loc_us-gaap_LineOfCreditMember_0E4FAE99711B9DA122EE836F7B4A9431" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityAxis" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_EF9B7514001079E87F73836F7B4AC4DA" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4C74219CFA08A2E87788836F7B4AF81F" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_EF9B7514001079E87F73836F7B4AC4DA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_EF4E3CB8F1D8A1C0861B836F7B4B33C2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_EF9B7514001079E87F73836F7B4AC4DA" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_EF4E3CB8F1D8A1C0861B836F7B4B33C2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_EF4E3CB8F1D8A1C0861B836F7B4B33C2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_EF9B7514001079E87F73836F7B4AC4DA" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_EF4E3CB8F1D8A1C0861B836F7B4B33C2" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_WellsFargoBankMember" xlink:label="loc_enph_WellsFargoBankMember_069C81BD383CB93F4552836F7B4BCF65" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_EF4E3CB8F1D8A1C0861B836F7B4B33C2" xlink:to="loc_enph_WellsFargoBankMember_069C81BD383CB93F4552836F7B4BCF65" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_F41ED0DCDEC747BA7631836F7B4BD7D1" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4C74219CFA08A2E87788836F7B4AF81F" xlink:to="loc_us-gaap_CreditFacilityAxis_F41ED0DCDEC747BA7631836F7B4BD7D1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_6A36933DF56C4D4FBC6E836F7B4BCA71_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_F41ED0DCDEC747BA7631836F7B4BD7D1" xlink:to="loc_us-gaap_CreditFacilityDomain_6A36933DF56C4D4FBC6E836F7B4BCA71_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_6A36933DF56C4D4FBC6E836F7B4BCA71" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_F41ED0DCDEC747BA7631836F7B4BD7D1" xlink:to="loc_us-gaap_CreditFacilityDomain_6A36933DF56C4D4FBC6E836F7B4BCA71" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_5EE3815C1E086D1D6741836F7B4BF9AC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_6A36933DF56C4D4FBC6E836F7B4BCA71" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_5EE3815C1E086D1D6741836F7B4BF9AC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_4B081AA7C1CF3542DA88836F7B4B6FD7" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4C74219CFA08A2E87788836F7B4AF81F" xlink:to="loc_us-gaap_VariableRateAxis_4B081AA7C1CF3542DA88836F7B4B6FD7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_7107AC256DFB7603B576836F7B4B702B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_4B081AA7C1CF3542DA88836F7B4B6FD7" xlink:to="loc_us-gaap_VariableRateDomain_7107AC256DFB7603B576836F7B4B702B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_7107AC256DFB7603B576836F7B4B702B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_4B081AA7C1CF3542DA88836F7B4B6FD7" xlink:to="loc_us-gaap_VariableRateDomain_7107AC256DFB7603B576836F7B4B702B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_BCDFAE7ED1CA9917166B836F7B4B71DB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_7107AC256DFB7603B576836F7B4B702B" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_BCDFAE7ED1CA9917166B836F7B4B71DB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_81309F77BED64F1D4B29836F7B4C136D" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4C74219CFA08A2E87788836F7B4AF81F" xlink:to="loc_us-gaap_RangeAxis_81309F77BED64F1D4B29836F7B4C136D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_3835570A3D2DAD7323BE836F7B4CD466_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_81309F77BED64F1D4B29836F7B4C136D" xlink:to="loc_us-gaap_RangeMember_3835570A3D2DAD7323BE836F7B4CD466_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_3835570A3D2DAD7323BE836F7B4CD466" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_81309F77BED64F1D4B29836F7B4C136D" xlink:to="loc_us-gaap_RangeMember_3835570A3D2DAD7323BE836F7B4CD466" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_0132608DEE6F08CCD076836F7B4C70D2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_3835570A3D2DAD7323BE836F7B4CD466" xlink:to="loc_us-gaap_MinimumMember_0132608DEE6F08CCD076836F7B4C70D2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_E6C0E0EFEEFA647288D6836F7B4CB3D4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_3835570A3D2DAD7323BE836F7B4CD466" xlink:to="loc_us-gaap_MaximumMember_E6C0E0EFEEFA647288D6836F7B4CB3D4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_0D8D310A67CD5BEEE353836F7B4CB18E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_FEB7DE4F249E7879866D836F7B4C3CF2" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_0D8D310A67CD5BEEE353836F7B4CB18E" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_LineOfCreditFacilityAccordionFeature" xlink:label="loc_enph_LineOfCreditFacilityAccordionFeature_C7E30E915B3E0081B72C836F7B4C05E0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_FEB7DE4F249E7879866D836F7B4C3CF2" xlink:to="loc_enph_LineOfCreditFacilityAccordionFeature_C7E30E915B3E0081B72C836F7B4C05E0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_79724F43BB0AE6D8E2B1836F7B4C1CA7" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_FEB7DE4F249E7879866D836F7B4C3CF2" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_79724F43BB0AE6D8E2B1836F7B4C1CA7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage" xlink:label="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_876960D36B587A58C6D1836F7B4CB555" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_FEB7DE4F249E7879866D836F7B4C3CF2" xlink:to="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_876960D36B587A58C6D1836F7B4CB555" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_AmountOfLiquidityRequiredForDebtCompliance" xlink:label="loc_enph_AmountOfLiquidityRequiredForDebtCompliance_8B3313A8BC8057A4AF31836F7B4C39D6" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_FEB7DE4F249E7879866D836F7B4C3CF2" xlink:to="loc_enph_AmountOfLiquidityRequiredForDebtCompliance_8B3313A8BC8057A4AF31836F7B4C39D6" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_AmountOfUndrawnCreditForDebtCompliance" xlink:label="loc_enph_AmountOfUndrawnCreditForDebtCompliance_D880C1C6F9BA6DCFF1A5836F7B4C3146" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_FEB7DE4F249E7879866D836F7B4C3CF2" xlink:to="loc_enph_AmountOfUndrawnCreditForDebtCompliance_D880C1C6F9BA6DCFF1A5836F7B4C3146" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCredit" xlink:label="loc_us-gaap_LineOfCredit_908A2AEC884FCF54C3B5836F7B4CCF34" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_FEB7DE4F249E7879866D836F7B4C3CF2" xlink:to="loc_us-gaap_LineOfCredit_908A2AEC884FCF54C3B5836F7B4CCF34" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_3663C0E45B67D8407213836F7B5254B8" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_FEB7DE4F249E7879866D836F7B4C3CF2" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_3663C0E45B67D8407213836F7B5254B8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtWeightedAverageInterestRate" xlink:label="loc_us-gaap_DebtWeightedAverageInterestRate_549921D30ACF2B2DEB8C836F7B52CC71" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_FEB7DE4F249E7879866D836F7B4C3CF2" xlink:to="loc_us-gaap_DebtWeightedAverageInterestRate_549921D30ACF2B2DEB8C836F7B52CC71" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/DebtTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/DebtTermLoanDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityLineItems" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_1F8C537D6943E79AF27A870F05F434FE" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityTable" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_884EFA00E1F7C66CA324870F05F3AAD7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_1F8C537D6943E79AF27A870F05F434FE" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_884EFA00E1F7C66CA324870F05F3AAD7" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_EC15FA07DFCF3CF938F9870F05F342A2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_884EFA00E1F7C66CA324870F05F3AAD7" xlink:to="loc_us-gaap_RangeAxis_EC15FA07DFCF3CF938F9870F05F342A2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_4F825B055F5211623F74870F05F33DC1_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_EC15FA07DFCF3CF938F9870F05F342A2" xlink:to="loc_us-gaap_RangeMember_4F825B055F5211623F74870F05F33DC1_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_4F825B055F5211623F74870F05F33DC1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_EC15FA07DFCF3CF938F9870F05F342A2" xlink:to="loc_us-gaap_RangeMember_4F825B055F5211623F74870F05F33DC1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_540C4FFE7E9BA20976C1870F05F3ED3C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_4F825B055F5211623F74870F05F33DC1" xlink:to="loc_us-gaap_MinimumMember_540C4FFE7E9BA20976C1870F05F3ED3C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_E32B86565C7C384B061D870F05F37A54" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_4F825B055F5211623F74870F05F33DC1" xlink:to="loc_us-gaap_MaximumMember_E32B86565C7C384B061D870F05F37A54" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_65481A7E6B16393C564C870F05F494E9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_884EFA00E1F7C66CA324870F05F3AAD7" xlink:to="loc_us-gaap_VariableRateAxis_65481A7E6B16393C564C870F05F494E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_821CFC29CB3A72998556870F05F4743C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_65481A7E6B16393C564C870F05F494E9" xlink:to="loc_us-gaap_VariableRateDomain_821CFC29CB3A72998556870F05F4743C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_821CFC29CB3A72998556870F05F4743C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_65481A7E6B16393C564C870F05F494E9" xlink:to="loc_us-gaap_VariableRateDomain_821CFC29CB3A72998556870F05F4743C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_8E4F0169596A46F66AB1870F05F4BC15" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_821CFC29CB3A72998556870F05F4743C" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_8E4F0169596A46F66AB1870F05F4BC15" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityAxis" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_9E3014E33E38DB765228870F05F4037F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_884EFA00E1F7C66CA324870F05F3AAD7" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_9E3014E33E38DB765228870F05F4037F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_6E3818EE28D72506C1E5870F05F45165_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_9E3014E33E38DB765228870F05F4037F" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_6E3818EE28D72506C1E5870F05F45165_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_6E3818EE28D72506C1E5870F05F45165" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_9E3014E33E38DB765228870F05F4037F" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_6E3818EE28D72506C1E5870F05F45165" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_TennenbaumCapitalPartnersLLCMember" xlink:label="loc_enph_TennenbaumCapitalPartnersLLCMember_2BE0282ED411299667C4870F05F47DEA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_6E3818EE28D72506C1E5870F05F45165" xlink:to="loc_enph_TennenbaumCapitalPartnersLLCMember_2BE0282ED411299667C4870F05F47DEA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_BBFFB54D66FFD8621FCE870F05F4D3A8" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_884EFA00E1F7C66CA324870F05F3AAD7" xlink:to="loc_us-gaap_CreditFacilityAxis_BBFFB54D66FFD8621FCE870F05F4D3A8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_A65505E10584D6EBDC7A870F05F48BDA_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_BBFFB54D66FFD8621FCE870F05F4D3A8" xlink:to="loc_us-gaap_CreditFacilityDomain_A65505E10584D6EBDC7A870F05F48BDA_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_A65505E10584D6EBDC7A870F05F48BDA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_BBFFB54D66FFD8621FCE870F05F4D3A8" xlink:to="loc_us-gaap_CreditFacilityDomain_A65505E10584D6EBDC7A870F05F48BDA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SecuredDebtMember" xlink:label="loc_us-gaap_SecuredDebtMember_C62A8CE66DDAF72A41E8870F05F4EF3C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_A65505E10584D6EBDC7A870F05F48BDA" xlink:to="loc_us-gaap_SecuredDebtMember_C62A8CE66DDAF72A41E8870F05F4EF3C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_DF1D80B3475A199BD75A870F05F4AFD0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_1F8C537D6943E79AF27A870F05F434FE" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_DF1D80B3475A199BD75A870F05F4AFD0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_96F5A77CBA39E0789BA6870F05F5DCD9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_1F8C537D6943E79AF27A870F05F434FE" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_96F5A77CBA39E0789BA6870F05F5DCD9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityInterestRateDuringPeriod" xlink:label="loc_us-gaap_LineOfCreditFacilityInterestRateDuringPeriod_D40A399CA0B1EBA30ACF870F05F59023" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_1F8C537D6943E79AF27A870F05F434FE" xlink:to="loc_us-gaap_LineOfCreditFacilityInterestRateDuringPeriod_D40A399CA0B1EBA30ACF870F05F59023" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_LineofCreditFacilityReductionofInterestRateDuringPeriodPercent" xlink:label="loc_enph_LineofCreditFacilityReductionofInterestRateDuringPeriodPercent_C9DAA8603167F494F0C7870F05F5ADEC" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_1F8C537D6943E79AF27A870F05F434FE" xlink:to="loc_enph_LineofCreditFacilityReductionofInterestRateDuringPeriodPercent_C9DAA8603167F494F0C7870F05F5ADEC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_1BAA118BF131046A6AE9870F05F5A015" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_1F8C537D6943E79AF27A870F05F434FE" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_1BAA118BF131046A6AE9870F05F5A015" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_LineofCreditFacilityClosingFeePercentage" xlink:label="loc_enph_LineofCreditFacilityClosingFeePercentage_7274B5614501869CB5EE870F05F5F23E" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_1F8C537D6943E79AF27A870F05F434FE" xlink:to="loc_enph_LineofCreditFacilityClosingFeePercentage_7274B5614501869CB5EE870F05F5F23E" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_LineofCreditFacilityPrepaymentFeePercent" xlink:label="loc_enph_LineofCreditFacilityPrepaymentFeePercent_E6F50B24525BB32658D7870F05F54056" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_1F8C537D6943E79AF27A870F05F434FE" xlink:to="loc_enph_LineofCreditFacilityPrepaymentFeePercent_E6F50B24525BB32658D7870F05F54056" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/DescriptionOfBusiness" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/DescriptionOfBusinessNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductInformationLineItems" xlink:label="loc_us-gaap_ProductInformationLineItems_EAC54F27B3566B3230FFC03FAC234EC0" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfProductInformationTable" xlink:label="loc_us-gaap_ScheduleOfProductInformationTable_D00BD23A66C280DB8FC3C03FAC22B161" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ProductInformationLineItems_EAC54F27B3566B3230FFC03FAC234EC0" xlink:to="loc_us-gaap_ScheduleOfProductInformationTable_D00BD23A66C280DB8FC3C03FAC22B161" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductOrServiceAxis" xlink:label="loc_us-gaap_ProductOrServiceAxis_1A2014723E34349A041CC03FAC222DC5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfProductInformationTable_D00BD23A66C280DB8FC3C03FAC22B161" xlink:to="loc_us-gaap_ProductOrServiceAxis_1A2014723E34349A041CC03FAC222DC5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductsAndServicesDomain" xlink:label="loc_us-gaap_ProductsAndServicesDomain_CEE9A0A6630E33EB81F3C03FAC2254D8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ProductOrServiceAxis_1A2014723E34349A041CC03FAC222DC5" xlink:to="loc_us-gaap_ProductsAndServicesDomain_CEE9A0A6630E33EB81F3C03FAC2254D8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductsAndServicesDomain" xlink:label="loc_us-gaap_ProductsAndServicesDomain_CEE9A0A6630E33EB81F3C03FAC2254D8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ProductOrServiceAxis_1A2014723E34349A041CC03FAC222DC5" xlink:to="loc_us-gaap_ProductsAndServicesDomain_CEE9A0A6630E33EB81F3C03FAC2254D8" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_MicroinverterMember" xlink:label="loc_enph_MicroinverterMember_84AF48ECAC7B20854565C03FAC22BF22" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductsAndServicesDomain_CEE9A0A6630E33EB81F3C03FAC2254D8" xlink:to="loc_enph_MicroinverterMember_84AF48ECAC7B20854565C03FAC22BF22" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_ResidentialAndCommercialSystemsMember" xlink:label="loc_enph_ResidentialAndCommercialSystemsMember_9B06406CD06DF1991145C03FAC2392C1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductsAndServicesDomain_CEE9A0A6630E33EB81F3C03FAC2254D8" xlink:to="loc_enph_ResidentialAndCommercialSystemsMember_9B06406CD06DF1991145C03FAC2392C1" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_NumberOfProductShipped" xlink:label="loc_enph_NumberOfProductShipped_FFBBF337588CC04CE34AC03FAC231A6E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_EAC54F27B3566B3230FFC03FAC234EC0" xlink:to="loc_enph_NumberOfProductShipped_FFBBF337588CC04CE34AC03FAC231A6E" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_NumberOfWatts" xlink:label="loc_enph_NumberOfWatts_E77E82EF998B10FEF015C03FAC23C347" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_EAC54F27B3566B3230FFC03FAC234EC0" xlink:to="loc_enph_NumberOfWatts_E77E82EF998B10FEF015C03FAC23C347" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_NumberOfProductDeployed" xlink:label="loc_enph_NumberOfProductDeployed_3970E6CCF4DEAA929E5AC03FAC233DF3" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_EAC54F27B3566B3230FFC03FAC234EC0" xlink:to="loc_enph_NumberOfProductDeployed_3970E6CCF4DEAA929E5AC03FAC233DF3" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_NumberOfCountriesInWhichProductIsDeployed" xlink:label="loc_enph_NumberOfCountriesInWhichProductIsDeployed_4270EA71F024FD60708CC03FAC23B8D6" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_EAC54F27B3566B3230FFC03FAC234EC0" xlink:to="loc_enph_NumberOfCountriesInWhichProductIsDeployed_4270EA71F024FD60708CC03FAC23B8D6" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/DocumentAndEntityInformation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/FairValueMeasurements" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/FairValueMeasurementsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DerivativeLineItems" xlink:label="loc_us-gaap_DerivativeLineItems_5526A9674A6FECA5339FB4FE0DA2146A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_CC11517C28D0253DF3AEB4FE0DA040BE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_5526A9674A6FECA5339FB4FE0DA2146A" xlink:to="loc_us-gaap_DerivativeTable_CC11517C28D0253DF3AEB4FE0DA040BE" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_B5849D65E1F7AD64F845B4FE0DA0B7E2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_CC11517C28D0253DF3AEB4FE0DA040BE" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_B5849D65E1F7AD64F845B4FE0DA0B7E2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_4F5933EF4492FA26A00BB4FE0DA19C0B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_B5849D65E1F7AD64F845B4FE0DA0B7E2" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_4F5933EF4492FA26A00BB4FE0DA19C0B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_4F5933EF4492FA26A00BB4FE0DA19C0B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_B5849D65E1F7AD64F845B4FE0DA0B7E2" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_4F5933EF4492FA26A00BB4FE0DA19C0B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ForeignExchangeForwardMember" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_2E6469D4F14DE3AF7C3DB4FE0DA1BBB7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_4F5933EF4492FA26A00BB4FE0DA19C0B" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_2E6469D4F14DE3AF7C3DB4FE0DA1BBB7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_6E194B826A4BAA4A7273B4FE0DA11A9B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_CC11517C28D0253DF3AEB4FE0DA040BE" xlink:to="loc_us-gaap_HedgingDesignationAxis_6E194B826A4BAA4A7273B4FE0DA11A9B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_60E0DA1B30B602F72103B4FE0DA1A3C6_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_6E194B826A4BAA4A7273B4FE0DA11A9B" xlink:to="loc_us-gaap_HedgingDesignationDomain_60E0DA1B30B602F72103B4FE0DA1A3C6_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_60E0DA1B30B602F72103B4FE0DA1A3C6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_6E194B826A4BAA4A7273B4FE0DA11A9B" xlink:to="loc_us-gaap_HedgingDesignationDomain_60E0DA1B30B602F72103B4FE0DA1A3C6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NondesignatedMember" xlink:label="loc_us-gaap_NondesignatedMember_863DDAF5F7DFEE2E7620B4FE0DA1A645" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_60E0DA1B30B602F72103B4FE0DA1A3C6" xlink:to="loc_us-gaap_NondesignatedMember_863DDAF5F7DFEE2E7620B4FE0DA1A645" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="loc_us-gaap_FinancialInstrumentAxis_899498F5BBC844EF392BB4FE0DA134A1" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_CC11517C28D0253DF3AEB4FE0DA040BE" xlink:to="loc_us-gaap_FinancialInstrumentAxis_899498F5BBC844EF392BB4FE0DA134A1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_7CC626BCBFE16D8C40D9B4FE0DA130C5_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_899498F5BBC844EF392BB4FE0DA134A1" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_7CC626BCBFE16D8C40D9B4FE0DA130C5_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_7CC626BCBFE16D8C40D9B4FE0DA130C5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_899498F5BBC844EF392BB4FE0DA134A1" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_7CC626BCBFE16D8C40D9B4FE0DA130C5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WarrantyRightsAndObligationsFairValueOptionMember" xlink:label="loc_us-gaap_WarrantyRightsAndObligationsFairValueOptionMember_7A35B917C474240BF344B4FE0DA18EC9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_7CC626BCBFE16D8C40D9B4FE0DA130C5" xlink:to="loc_us-gaap_WarrantyRightsAndObligationsFairValueOptionMember_7A35B917C474240BF344B4FE0DA18EC9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationTechniqueAxis" xlink:label="loc_us-gaap_ValuationTechniqueAxis_AD4A28C2E98C8C675DD6B4FE0DA10253" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_CC11517C28D0253DF3AEB4FE0DA040BE" xlink:to="loc_us-gaap_ValuationTechniqueAxis_AD4A28C2E98C8C675DD6B4FE0DA10253" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationTechniqueDomain" xlink:label="loc_us-gaap_ValuationTechniqueDomain_7C1E30F891A0C1497341B4FE0DA1BA59_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationTechniqueAxis_AD4A28C2E98C8C675DD6B4FE0DA10253" xlink:to="loc_us-gaap_ValuationTechniqueDomain_7C1E30F891A0C1497341B4FE0DA1BA59_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationTechniqueDomain" xlink:label="loc_us-gaap_ValuationTechniqueDomain_7C1E30F891A0C1497341B4FE0DA1BA59" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationTechniqueAxis_AD4A28C2E98C8C675DD6B4FE0DA10253" xlink:to="loc_us-gaap_ValuationTechniqueDomain_7C1E30F891A0C1497341B4FE0DA1BA59" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeApproachValuationTechniqueMember" xlink:label="loc_us-gaap_IncomeApproachValuationTechniqueMember_5AD4F7A714292AAD8873B4FE0DA29A08" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationTechniqueDomain_7C1E30F891A0C1497341B4FE0DA1BA59" xlink:to="loc_us-gaap_IncomeApproachValuationTechniqueMember_5AD4F7A714292AAD8873B4FE0DA29A08" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_B46A72AE9CC474B95691B4FE0DA2105C" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_CC11517C28D0253DF3AEB4FE0DA040BE" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_B46A72AE9CC474B95691B4FE0DA2105C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_7036E98967752B4771F0B4FE0DA21FEC_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_B46A72AE9CC474B95691B4FE0DA2105C" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_7036E98967752B4771F0B4FE0DA21FEC_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_7036E98967752B4771F0B4FE0DA21FEC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_B46A72AE9CC474B95691B4FE0DA2105C" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_7036E98967752B4771F0B4FE0DA21FEC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_A6E4C943C62FAC353CC4B4FE0DA2A6F1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_7036E98967752B4771F0B4FE0DA21FEC" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_A6E4C943C62FAC353CC4B4FE0DA2A6F1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_05C9EE9187526315AF4DB4FE0DA269EF" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_CC11517C28D0253DF3AEB4FE0DA040BE" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_05C9EE9187526315AF4DB4FE0DA269EF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_3D4733ECEADA419F8E8EB4FE0DA23701_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_05C9EE9187526315AF4DB4FE0DA269EF" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_3D4733ECEADA419F8E8EB4FE0DA23701_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_3D4733ECEADA419F8E8EB4FE0DA23701" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_05C9EE9187526315AF4DB4FE0DA269EF" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_3D4733ECEADA419F8E8EB4FE0DA23701" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_5443C560F884D63F332DB4FE0DA240BE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_3D4733ECEADA419F8E8EB4FE0DA23701" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_5443C560F884D63F332DB4FE0DA240BE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_DerivativeNotionalAmount" xlink:label="loc_invest_DerivativeNotionalAmount_447C0A7F0BD87FCD5F9DB4FE0DA24E26" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_5526A9674A6FECA5339FB4FE0DA2146A" xlink:to="loc_invest_DerivativeNotionalAmount_447C0A7F0BD87FCD5F9DB4FE0DA24E26" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments" xlink:label="loc_us-gaap_GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments_0817B4C34B5CBEEBE110B4FE0DA2DB85" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_5526A9674A6FECA5339FB4FE0DA2146A" xlink:to="loc_us-gaap_GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments_0817B4C34B5CBEEBE110B4FE0DA2DB85" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_WarrantyObligationsatFairValueDecreaseinFairValueResultingfromOnePercentagePointIncreaseinDiscountRate" xlink:label="loc_enph_WarrantyObligationsatFairValueDecreaseinFairValueResultingfromOnePercentagePointIncreaseinDiscountRate_E7CDF29F5DB271675B62B4FE0DA3E820" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_5526A9674A6FECA5339FB4FE0DA2146A" xlink:to="loc_enph_WarrantyObligationsatFairValueDecreaseinFairValueResultingfromOnePercentagePointIncreaseinDiscountRate_E7CDF29F5DB271675B62B4FE0DA3E820" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_WarrantyObligationsAtFairValueIncreaseInFairValueResultingFromOnePercentagePointDecreaseInDiscountRate" xlink:label="loc_enph_WarrantyObligationsAtFairValueIncreaseInFairValueResultingFromOnePercentagePointDecreaseInDiscountRate_0B85A1B3B93290849651B4FE0DA36297" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_5526A9674A6FECA5339FB4FE0DA2146A" xlink:to="loc_enph_WarrantyObligationsAtFairValueIncreaseInFairValueResultingFromOnePercentagePointDecreaseInDiscountRate_0B85A1B3B93290849651B4FE0DA36297" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/FairValueMeasurementsScheduleOfFinancialInstrumentsMeasuredAtFairValueOnRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7B1582B0463F04F0BC975D4EE7E561B3" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7BFFFB6B346EC91953B85D4EE7E43EE0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7B1582B0463F04F0BC975D4EE7E561B3" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7BFFFB6B346EC91953B85D4EE7E43EE0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_46073345CA8DE801AA725D4EE7E4C2E4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7BFFFB6B346EC91953B85D4EE7E43EE0" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_46073345CA8DE801AA725D4EE7E4C2E4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_674A519C139AA9D09BCE5D4EE7E48D3F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_46073345CA8DE801AA725D4EE7E4C2E4" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_674A519C139AA9D09BCE5D4EE7E48D3F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_674A519C139AA9D09BCE5D4EE7E48D3F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_46073345CA8DE801AA725D4EE7E4C2E4" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_674A519C139AA9D09BCE5D4EE7E48D3F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_1B9CEF512A9789509E645D4EE7E4F2C2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_674A519C139AA9D09BCE5D4EE7E48D3F" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_1B9CEF512A9789509E645D4EE7E4F2C2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_B425C1EA1C9AB4C1DB135D4EE7E49021" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7BFFFB6B346EC91953B85D4EE7E43EE0" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_B425C1EA1C9AB4C1DB135D4EE7E49021" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_447B9AF7E2958ABF7AD35D4EE7E4AADE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_B425C1EA1C9AB4C1DB135D4EE7E49021" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_447B9AF7E2958ABF7AD35D4EE7E4AADE_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_447B9AF7E2958ABF7AD35D4EE7E4AADE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_B425C1EA1C9AB4C1DB135D4EE7E49021" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_447B9AF7E2958ABF7AD35D4EE7E4AADE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_51D2F35F34A9FEE719AE5D4EE7E47A3C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_447B9AF7E2958ABF7AD35D4EE7E4AADE" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_51D2F35F34A9FEE719AE5D4EE7E47A3C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_5A2B93A8CC49C8E868585D4EE7E4E350" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_447B9AF7E2958ABF7AD35D4EE7E4AADE" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_5A2B93A8CC49C8E868585D4EE7E4E350" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="loc_us-gaap_FinancialInstrumentAxis_E0138F88A9D577D800935D4EE7E45992" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7BFFFB6B346EC91953B85D4EE7E43EE0" xlink:to="loc_us-gaap_FinancialInstrumentAxis_E0138F88A9D577D800935D4EE7E45992" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8BCC36E496749B3B4DEE5D4EE7E4A7E3_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_E0138F88A9D577D800935D4EE7E45992" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8BCC36E496749B3B4DEE5D4EE7E4A7E3_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8BCC36E496749B3B4DEE5D4EE7E4A7E3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_E0138F88A9D577D800935D4EE7E45992" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8BCC36E496749B3B4DEE5D4EE7E4A7E3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WarrantyRightsAndObligationsFairValueOptionMember" xlink:label="loc_us-gaap_WarrantyRightsAndObligationsFairValueOptionMember_2656F3EA565085735BFB5D4EE7E5C47F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8BCC36E496749B3B4DEE5D4EE7E4A7E3" xlink:to="loc_us-gaap_WarrantyRightsAndObligationsFairValueOptionMember_2656F3EA565085735BFB5D4EE7E5C47F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GuaranteesMember" xlink:label="loc_us-gaap_GuaranteesMember_3B664FB440071DD812C15D4EE7E545C0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8BCC36E496749B3B4DEE5D4EE7E4A7E3" xlink:to="loc_us-gaap_GuaranteesMember_3B664FB440071DD812C15D4EE7E545C0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AssetsFairValueDisclosureAbstract" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_DF269F49A1E2E1199D905D4EE7E538FF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7B1582B0463F04F0BC975D4EE7E561B3" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_DF269F49A1E2E1199D905D4EE7E538FF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ForeignCurrencyContractAssetFairValueDisclosure" xlink:label="loc_us-gaap_ForeignCurrencyContractAssetFairValueDisclosure_1A27EBECDF05641396725D4EE7E57262" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_DF269F49A1E2E1199D905D4EE7E538FF" xlink:to="loc_us-gaap_ForeignCurrencyContractAssetFairValueDisclosure_1A27EBECDF05641396725D4EE7E57262" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_71D2E55F82D33C20876F5D4EE7E5C45B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7B1582B0463F04F0BC975D4EE7E561B3" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_71D2E55F82D33C20876F5D4EE7E5C45B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure" xlink:label="loc_us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure_7C1721D8E8BB9DAFF6E05D4EE7E52F44" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_71D2E55F82D33C20876F5D4EE7E5C45B" xlink:to="loc_us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure_7C1721D8E8BB9DAFF6E05D4EE7E52F44" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_A7EC80F6EA8E18DF82605D4EE7E5B0B6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_71D2E55F82D33C20876F5D4EE7E5C45B" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_A7EC80F6EA8E18DF82605D4EE7E5B0B6" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/FairValueMeasurementsScheduleOfReconciliationOfBeginningAndEndingBalancesOfWarrantyObligationsMeasuredAtFairValueDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_93D4477590C75C6A2FB25D4EE7AED8DF" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_555CB741C89F0B63041C5D4EE7AD6DE2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_93D4477590C75C6A2FB25D4EE7AED8DF" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_555CB741C89F0B63041C5D4EE7AD6DE2" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_E63D9DB5406942459F055D4EE7AE8284" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_555CB741C89F0B63041C5D4EE7AD6DE2" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_E63D9DB5406942459F055D4EE7AE8284" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_70EEC5479A7E671F49AC5D4EE7AE4442_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_E63D9DB5406942459F055D4EE7AE8284" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_70EEC5479A7E671F49AC5D4EE7AE4442_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_70EEC5479A7E671F49AC5D4EE7AE4442" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_E63D9DB5406942459F055D4EE7AE8284" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_70EEC5479A7E671F49AC5D4EE7AE4442" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_736034A2B1CC86E9BC515D4EE7AE47BB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_70EEC5479A7E671F49AC5D4EE7AE4442" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_736034A2B1CC86E9BC515D4EE7AE47BB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8817D91955202F06ABA65D4EE7AE4F27" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_555CB741C89F0B63041C5D4EE7AD6DE2" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8817D91955202F06ABA65D4EE7AE4F27" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7C732DF01FB64D1B4E535D4EE7AEC1EA_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8817D91955202F06ABA65D4EE7AE4F27" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7C732DF01FB64D1B4E535D4EE7AEC1EA_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7C732DF01FB64D1B4E535D4EE7AEC1EA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8817D91955202F06ABA65D4EE7AE4F27" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7C732DF01FB64D1B4E535D4EE7AEC1EA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_93997ABEDB4978D7BDC55D4EE7AE216C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7C732DF01FB64D1B4E535D4EE7AEC1EA" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_93997ABEDB4978D7BDC55D4EE7AE216C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="loc_us-gaap_FinancialInstrumentAxis_89185D6CC86E25CF2F385D4EE7AE9F1B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_555CB741C89F0B63041C5D4EE7AD6DE2" xlink:to="loc_us-gaap_FinancialInstrumentAxis_89185D6CC86E25CF2F385D4EE7AE9F1B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_CED312B390B3AD0D8D245D4EE7AE143E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_89185D6CC86E25CF2F385D4EE7AE9F1B" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_CED312B390B3AD0D8D245D4EE7AE143E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_CED312B390B3AD0D8D245D4EE7AE143E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_89185D6CC86E25CF2F385D4EE7AE9F1B" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_CED312B390B3AD0D8D245D4EE7AE143E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WarrantyRightsAndObligationsFairValueOptionMember" xlink:label="loc_us-gaap_WarrantyRightsAndObligationsFairValueOptionMember_F77F410959BF074D92FD5D4EE7AE5759" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_CED312B390B3AD0D8D245D4EE7AE143E" xlink:to="loc_us-gaap_WarrantyRightsAndObligationsFairValueOptionMember_F77F410959BF074D92FD5D4EE7AE5759" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_2C010EE088DA5E6F0D325D4EE7AE7874" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_93D4477590C75C6A2FB25D4EE7AED8DF" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_2C010EE088DA5E6F0D325D4EE7AE7874" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_619A38A760332CCE700C5D4EE7AE6679" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_2C010EE088DA5E6F0D325D4EE7AE7874" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_619A38A760332CCE700C5D4EE7AE6679" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIssues" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIssues_471AA500222AC14F7C475D4EE7AEEF26" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_2C010EE088DA5E6F0D325D4EE7AE7874" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIssues_471AA500222AC14F7C475D4EE7AEEF26" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_FairValueMeasurementwithUnobservableInputsReconciliationsRecurringBasisLiabilityChangeinEstimate" xlink:label="loc_enph_FairValueMeasurementwithUnobservableInputsReconciliationsRecurringBasisLiabilityChangeinEstimate_DDEE13C0C98AB32EF2085D4EE7AFBE44" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_2C010EE088DA5E6F0D325D4EE7AE7874" xlink:to="loc_enph_FairValueMeasurementwithUnobservableInputsReconciliationsRecurringBasisLiabilityChangeinEstimate_DDEE13C0C98AB32EF2085D4EE7AFBE44" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements_C006A3C98491CEC4C9AF5D4EE7AF66EF" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_2C010EE088DA5E6F0D325D4EE7AE7874" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements_C006A3C98491CEC4C9AF5D4EE7AF66EF" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_FairValueMeasurementwithUnobservableInputsReconciliationsRecurringBasisLiabilityAccretionExpense" xlink:label="loc_enph_FairValueMeasurementwithUnobservableInputsReconciliationsRecurringBasisLiabilityAccretionExpense_F41D60F6A248586DB8B45D4EE7AF6CE5" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_2C010EE088DA5E6F0D325D4EE7AE7874" xlink:to="loc_enph_FairValueMeasurementwithUnobservableInputsReconciliationsRecurringBasisLiabilityAccretionExpense_F41D60F6A248586DB8B45D4EE7AF6CE5" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityAdjustments" xlink:label="loc_enph_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityAdjustments_A8E33590D1F5491AB7E55D4EE7AF72AB" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_2C010EE088DA5E6F0D325D4EE7AE7874" xlink:to="loc_enph_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityAdjustments_A8E33590D1F5491AB7E55D4EE7AF72AB" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/FairValueMeasurementsSummaryOfSignificantUnobservableInputsUsedInFairValueMeasurementsOfCompanysLiabilitiesDesignatedAsLevel3Details" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_EC15642EE5CB44DA3057CDBCF327CE4E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_5EAC7ABA963147432985CDBCF3261777" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_EC15642EE5CB44DA3057CDBCF327CE4E" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_5EAC7ABA963147432985CDBCF3261777" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_470510ED3A7B9B683E3ECDBCF326FBDA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_5EAC7ABA963147432985CDBCF3261777" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_470510ED3A7B9B683E3ECDBCF326FBDA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_9203C53EC710F9C782B3CDBCF3267366_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_470510ED3A7B9B683E3ECDBCF326FBDA" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_9203C53EC710F9C782B3CDBCF3267366_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_9203C53EC710F9C782B3CDBCF3267366" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_470510ED3A7B9B683E3ECDBCF326FBDA" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_9203C53EC710F9C782B3CDBCF3267366" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_07BF7C83AEBFD2E4BE30CDBCF3260B5C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_9203C53EC710F9C782B3CDBCF3267366" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_07BF7C83AEBFD2E4BE30CDBCF3260B5C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8276BC052F6FBF2FA89ACDBCF3265620" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_5EAC7ABA963147432985CDBCF3261777" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8276BC052F6FBF2FA89ACDBCF3265620" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_EC7853587D6C87420A59CDBCF32660B6_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8276BC052F6FBF2FA89ACDBCF3265620" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_EC7853587D6C87420A59CDBCF32660B6_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_EC7853587D6C87420A59CDBCF32660B6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8276BC052F6FBF2FA89ACDBCF3265620" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_EC7853587D6C87420A59CDBCF32660B6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_CD374B2E202F14CCBEDDCDBCF326FA2F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_EC7853587D6C87420A59CDBCF32660B6" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_CD374B2E202F14CCBEDDCDBCF326FA2F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="loc_us-gaap_FinancialInstrumentAxis_5BD7BA6A72382A2A0736CDBCF3266D7B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_5EAC7ABA963147432985CDBCF3261777" xlink:to="loc_us-gaap_FinancialInstrumentAxis_5BD7BA6A72382A2A0736CDBCF3266D7B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_BE101E1AB996994B13D3CDBCF326CA6D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_5BD7BA6A72382A2A0736CDBCF3266D7B" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_BE101E1AB996994B13D3CDBCF326CA6D_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_BE101E1AB996994B13D3CDBCF326CA6D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_5BD7BA6A72382A2A0736CDBCF3266D7B" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_BE101E1AB996994B13D3CDBCF326CA6D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WarrantyRightsAndObligationsFairValueOptionMember" xlink:label="loc_us-gaap_WarrantyRightsAndObligationsFairValueOptionMember_BD42DC003F4B7911AEBDCDBCF327B72F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_BE101E1AB996994B13D3CDBCF326CA6D" xlink:to="loc_us-gaap_WarrantyRightsAndObligationsFairValueOptionMember_BD42DC003F4B7911AEBDCDBCF327B72F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GuaranteesMember" xlink:label="loc_us-gaap_GuaranteesMember_89B9BFA9880256FC8ED3CDC14F672CD9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_BE101E1AB996994B13D3CDBCF326CA6D" xlink:to="loc_us-gaap_GuaranteesMember_89B9BFA9880256FC8ED3CDC14F672CD9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationTechniqueAxis" xlink:label="loc_us-gaap_ValuationTechniqueAxis_889582EC79461D3636F4CDBCF327BECE" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_5EAC7ABA963147432985CDBCF3261777" xlink:to="loc_us-gaap_ValuationTechniqueAxis_889582EC79461D3636F4CDBCF327BECE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationTechniqueDomain" xlink:label="loc_us-gaap_ValuationTechniqueDomain_81EEE3DECDA4D8835001CDBCF3270350_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationTechniqueAxis_889582EC79461D3636F4CDBCF327BECE" xlink:to="loc_us-gaap_ValuationTechniqueDomain_81EEE3DECDA4D8835001CDBCF3270350_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationTechniqueDomain" xlink:label="loc_us-gaap_ValuationTechniqueDomain_81EEE3DECDA4D8835001CDBCF3270350" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationTechniqueAxis_889582EC79461D3636F4CDBCF327BECE" xlink:to="loc_us-gaap_ValuationTechniqueDomain_81EEE3DECDA4D8835001CDBCF3270350" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeApproachValuationTechniqueMember" xlink:label="loc_us-gaap_IncomeApproachValuationTechniqueMember_CA6382446CC8F3987E75CDBCF3275A67" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationTechniqueDomain_81EEE3DECDA4D8835001CDBCF3270350" xlink:to="loc_us-gaap_IncomeApproachValuationTechniqueMember_CA6382446CC8F3987E75CDBCF3275A67" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_FairValueInputsProfitElementandRiskPremium" xlink:label="loc_enph_FairValueInputsProfitElementandRiskPremium_4492925C04254D072820CDBCF3270EC1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_EC15642EE5CB44DA3057CDBCF327CE4E" xlink:to="loc_enph_FairValueInputsProfitElementandRiskPremium_4492925C04254D072820CDBCF3270EC1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsEntityCreditRisk" xlink:label="loc_us-gaap_FairValueInputsEntityCreditRisk_3A5C0FD21D969032A0F6CDBCF327C9D4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_EC15642EE5CB44DA3057CDBCF327CE4E" xlink:to="loc_us-gaap_FairValueInputsEntityCreditRisk_3A5C0FD21D969032A0F6CDBCF327C9D4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsDiscountRate" xlink:label="loc_us-gaap_FairValueInputsDiscountRate_EDA6746787F2B443CC34CDBEEC0FDBA9" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_EC15642EE5CB44DA3057CDBCF327CE4E" xlink:to="loc_us-gaap_FairValueInputsDiscountRate_EDA6746787F2B443CC34CDBEEC0FDBA9" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/FairValueMeasurementsTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_AE523E0EA59C11BC4B468311200A9C8E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_DA84D4D3AC82A4254951831120095616" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_AE523E0EA59C11BC4B468311200A9C8E" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_DA84D4D3AC82A4254951831120095616" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="loc_us-gaap_FinancialInstrumentAxis_3D2A2A1C610A25F0037383112009050C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_DA84D4D3AC82A4254951831120095616" xlink:to="loc_us-gaap_FinancialInstrumentAxis_3D2A2A1C610A25F0037383112009050C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_FA261C212D349F80350B831120095458_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_3D2A2A1C610A25F0037383112009050C" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_FA261C212D349F80350B831120095458_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_FA261C212D349F80350B831120095458" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_3D2A2A1C610A25F0037383112009050C" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_FA261C212D349F80350B831120095458" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WarrantyRightsAndObligationsFairValueOptionMember" xlink:label="loc_us-gaap_WarrantyRightsAndObligationsFairValueOptionMember_EBE4ED396F0CB2C0B7DD831120097452" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_FA261C212D349F80350B831120095458" xlink:to="loc_us-gaap_WarrantyRightsAndObligationsFairValueOptionMember_EBE4ED396F0CB2C0B7DD831120097452" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock_2EF5EE64E5C7CAE167DF8311200A9E47" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_AE523E0EA59C11BC4B468311200A9C8E" xlink:to="loc_us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock_2EF5EE64E5C7CAE167DF8311200A9E47" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock_1B9B1FC3473C674F1F9D8311200AFDF0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_AE523E0EA59C11BC4B468311200A9C8E" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock_1B9B1FC3473C674F1F9D8311200AFDF0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock_C08C87A272718E6971418311200AF9BA" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_AE523E0EA59C11BC4B468311200A9C8E" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock_C08C87A272718E6971418311200AF9BA" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/IncomeTaxes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/IncomeTaxesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLossCarryforwardsLineItems" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLineItems_6D453DF03C5FFDA50FD3870F04EECD02" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLossCarryforwardsTable" xlink:label="loc_us-gaap_OperatingLossCarryforwardsTable_73BFCBE40C65FBED4436870F04E8DCDD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_6D453DF03C5FFDA50FD3870F04EECD02" xlink:to="loc_us-gaap_OperatingLossCarryforwardsTable_73BFCBE40C65FBED4436870F04E8DCDD" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_71B7A01CE2336B20AC6E870F04E9E29A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_73BFCBE40C65FBED4436870F04E8DCDD" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_71B7A01CE2336B20AC6E870F04E9E29A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_D011AB40E2C20A33A371870F04E91A9F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_71B7A01CE2336B20AC6E870F04E9E29A" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_D011AB40E2C20A33A371870F04E91A9F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_D011AB40E2C20A33A371870F04E91A9F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_71B7A01CE2336B20AC6E870F04E9E29A" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_D011AB40E2C20A33A371870F04E91A9F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DomesticCountryMember" xlink:label="loc_us-gaap_DomesticCountryMember_5C3E341A57B542F77094870F04EEE72E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_D011AB40E2C20A33A371870F04E91A9F" xlink:to="loc_us-gaap_DomesticCountryMember_5C3E341A57B542F77094870F04EEE72E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_7EB0824321A151579FB6870F04EEEFDC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_D011AB40E2C20A33A371870F04E91A9F" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_7EB0824321A151579FB6870F04EEEFDC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TaxCreditCarryforwardAxis" xlink:label="loc_us-gaap_TaxCreditCarryforwardAxis_A7EFE1EBD137F6B10E02870F04EEF1C1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_73BFCBE40C65FBED4436870F04E8DCDD" xlink:to="loc_us-gaap_TaxCreditCarryforwardAxis_A7EFE1EBD137F6B10E02870F04EEF1C1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TaxCreditCarryforwardNameDomain" xlink:label="loc_us-gaap_TaxCreditCarryforwardNameDomain_2C10E670CB7AEAFC3212870F04EE6308_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TaxCreditCarryforwardAxis_A7EFE1EBD137F6B10E02870F04EEF1C1" xlink:to="loc_us-gaap_TaxCreditCarryforwardNameDomain_2C10E670CB7AEAFC3212870F04EE6308_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TaxCreditCarryforwardNameDomain" xlink:label="loc_us-gaap_TaxCreditCarryforwardNameDomain_2C10E670CB7AEAFC3212870F04EE6308" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TaxCreditCarryforwardAxis_A7EFE1EBD137F6B10E02870F04EEF1C1" xlink:to="loc_us-gaap_TaxCreditCarryforwardNameDomain_2C10E670CB7AEAFC3212870F04EE6308" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ResearchMember" xlink:label="loc_us-gaap_ResearchMember_C73C02238610DE213778870F04EEC01D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardNameDomain_2C10E670CB7AEAFC3212870F04EE6308" xlink:to="loc_us-gaap_ResearchMember_C73C02238610DE213778870F04EEC01D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_BCF6FCBDEF69E4503C3E870F04EEA5F6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_6D453DF03C5FFDA50FD3870F04EECD02" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_BCF6FCBDEF69E4503C3E870F04EEA5F6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings_03C8E7B75480677D3E87870F04EE5B3A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_6D453DF03C5FFDA50FD3870F04EECD02" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings_03C8E7B75480677D3E87870F04EE5B3A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLossCarryforwards" xlink:label="loc_us-gaap_OperatingLossCarryforwards_104FB68FBB913282E14B870F04EF91A9" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_6D453DF03C5FFDA50FD3870F04EECD02" xlink:to="loc_us-gaap_OperatingLossCarryforwards_104FB68FBB913282E14B870F04EF91A9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TaxCreditCarryforwardAmount" xlink:label="loc_us-gaap_TaxCreditCarryforwardAmount_47FF447C159A3C01AA6A870F04EFF29D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_6D453DF03C5FFDA50FD3870F04EECD02" xlink:to="loc_us-gaap_TaxCreditCarryforwardAmount_47FF447C159A3C01AA6A870F04EFF29D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities" xlink:label="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities_D47BF2BF7B78A364EFAC870F04EF469F" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_6D453DF03C5FFDA50FD3870F04EECD02" xlink:to="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities_D47BF2BF7B78A364EFAC870F04EF469F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsPeriodIncreaseDecrease" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsPeriodIncreaseDecrease_8FAD40756394B5BD5E90870F04EF3CE5" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_6D453DF03C5FFDA50FD3870F04EECD02" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsPeriodIncreaseDecrease_8FAD40756394B5BD5E90870F04EF3CE5" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/IncomeTaxesScheduleOfDeferredTaxAssetsAndLiabilitiesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/IncomeTaxesScheduleOfDomesticAndForeignComponentsOfLossBeforeProvisionForIncomeTaxesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/IncomeTaxesScheduleOfEffectiveIncomeTaxRateReconciliationDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/IncomeTaxesScheduleOfProvisionForIncomeTaxesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/IncomeTaxesScheduleOfReconciliationOfTotalAmountsOfUnrecognizedTaxBenefitsDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/IncomeTaxesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/Inventory" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/InventorySummaryOfInventoryDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/InventoryTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/NetLossPerShare" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/NetLossPerShareScheduleOfPotentialCommonSharesOutstandingExcludedFromComputationOfDilutedNetLossPerShareAttributableToCommonStockholdersDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_F7A293569546C597652C5DD3C9E9E2B1" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_7D857F98BA9467A0CB4D5DD3C9E9036A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_F7A293569546C597652C5DD3C9E9E2B1" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_7D857F98BA9467A0CB4D5DD3C9E9036A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_245B6BB81DCD75FE84B65DD3C9E941FC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_7D857F98BA9467A0CB4D5DD3C9E9036A" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_245B6BB81DCD75FE84B65DD3C9E941FC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_FB2D539D10756706C5E25DD3C9E9921F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_245B6BB81DCD75FE84B65DD3C9E941FC" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_FB2D539D10756706C5E25DD3C9E9921F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_FB2D539D10756706C5E25DD3C9E9921F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_245B6BB81DCD75FE84B65DD3C9E941FC" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_FB2D539D10756706C5E25DD3C9E9921F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_35F5CDC15DD5C966D23E5DD3C9E95577" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_FB2D539D10756706C5E25DD3C9E9921F" xlink:to="loc_us-gaap_EmployeeStockOptionMember_35F5CDC15DD5C966D23E5DD3C9E95577" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_315B5EA91BF0CFDE5F4C5DD3C9E96D98" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_FB2D539D10756706C5E25DD3C9E9921F" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_315B5EA91BF0CFDE5F4C5DD3C9E96D98" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WarrantMember" xlink:label="loc_us-gaap_WarrantMember_7F6445FF6D9F8F4C9B515DD3C9E9E913" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_FB2D539D10756706C5E25DD3C9E9921F" xlink:to="loc_us-gaap_WarrantMember_7F6445FF6D9F8F4C9B515DD3C9E9E913" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_DF85590D9BA7DDE2F6E25DD3C9E919E0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_F7A293569546C597652C5DD3C9E9E2B1" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_DF85590D9BA7DDE2F6E25DD3C9E919E0" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/NetLossPerShareTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/PropertyAndEquipmentNet" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/PropertyAndEquipmentNetNarrativeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/PropertyAndEquipmentNetSummaryOfPropertyAndEquipmentDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4962395D90EA01CE70058FCF64E93815" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_62C37301610B29AB16238FCF64E861FE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4962395D90EA01CE70058FCF64E93815" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_62C37301610B29AB16238FCF64E861FE" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_7E74AF5143F0067522638FCF64E8ECE3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_62C37301610B29AB16238FCF64E861FE" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_7E74AF5143F0067522638FCF64E8ECE3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_B51E882F8C39C91FA76C8FCF64E8F1C3_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_7E74AF5143F0067522638FCF64E8ECE3" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_B51E882F8C39C91FA76C8FCF64E8F1C3_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_B51E882F8C39C91FA76C8FCF64E8F1C3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_7E74AF5143F0067522638FCF64E8ECE3" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_B51E882F8C39C91FA76C8FCF64E8F1C3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MachineryAndEquipmentMember" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_BA389AAD92C523BDCCCC8FCF64E8C360" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_B51E882F8C39C91FA76C8FCF64E8F1C3" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_BA389AAD92C523BDCCCC8FCF64E8C360" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_3774BCF1E005CD7F444C8FCF64E87135" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_B51E882F8C39C91FA76C8FCF64E8F1C3" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_3774BCF1E005CD7F444C8FCF64E87135" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ComputerEquipmentMember" xlink:label="loc_us-gaap_ComputerEquipmentMember_B7D3812C3B534AE1E70D8FCF64E89602" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_B51E882F8C39C91FA76C8FCF64E8F1C3" xlink:to="loc_us-gaap_ComputerEquipmentMember_B7D3812C3B534AE1E70D8FCF64E89602" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:label="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_8733AD5A7A5BF26822868FCF64E9568C" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_B51E882F8C39C91FA76C8FCF64E8F1C3" xlink:to="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_8733AD5A7A5BF26822868FCF64E9568C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LeaseholdImprovementsMember" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_75F34DBCF356022E91138FCF64E9E42C" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_B51E882F8C39C91FA76C8FCF64E8F1C3" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_75F34DBCF356022E91138FCF64E9E42C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConstructionInProgressMember" xlink:label="loc_us-gaap_ConstructionInProgressMember_82A3DE4B81621E422DF38FCF64E9146E" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_B51E882F8C39C91FA76C8FCF64E8F1C3" xlink:to="loc_us-gaap_ConstructionInProgressMember_82A3DE4B81621E422DF38FCF64E9146E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_88D9E3808FE9EE1E5EE18FCF64E98889" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_62C37301610B29AB16238FCF64E861FE" xlink:to="loc_us-gaap_RangeAxis_88D9E3808FE9EE1E5EE18FCF64E98889" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_73B3EFE3E2C26434311C8FCF64E90EDC_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_88D9E3808FE9EE1E5EE18FCF64E98889" xlink:to="loc_us-gaap_RangeMember_73B3EFE3E2C26434311C8FCF64E90EDC_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_73B3EFE3E2C26434311C8FCF64E90EDC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_88D9E3808FE9EE1E5EE18FCF64E98889" xlink:to="loc_us-gaap_RangeMember_73B3EFE3E2C26434311C8FCF64E90EDC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_D7C4316776854F4615DC8FCF64E9676B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_73B3EFE3E2C26434311C8FCF64E90EDC" xlink:to="loc_us-gaap_MinimumMember_D7C4316776854F4615DC8FCF64E9676B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_875527CC482FBD9123278FCF64E902B6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_73B3EFE3E2C26434311C8FCF64E90EDC" xlink:to="loc_us-gaap_MaximumMember_875527CC482FBD9123278FCF64E902B6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_ADD52AB3DAEAE66F61908FCF64E9061E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4962395D90EA01CE70058FCF64E93815" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_ADD52AB3DAEAE66F61908FCF64E9061E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_EF392E020B4D86C45B438FCF64E9333D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4962395D90EA01CE70058FCF64E93815" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_EF392E020B4D86C45B438FCF64E9333D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_3019E5BD868E22B1A7AB8FCF64E9DA03" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4962395D90EA01CE70058FCF64E93815" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_3019E5BD868E22B1A7AB8FCF64E9DA03" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_AC61821FDEE5ABF1AE6B8FCF64E9A5B9" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4962395D90EA01CE70058FCF64E93815" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_AC61821FDEE5ABF1AE6B8FCF64E9A5B9" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/PropertyAndEquipmentNetTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/QuarterlyFinancialInformationUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/QuarterlyFinancialInformationUnauditedScheduleOfQuarterlyFinancialInformationDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/QuarterlyFinancialInformationUnauditedTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/RestructuringAndOther" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/RestructuringAndOtherDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringCostAndReserveLineItems" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_B96AAEEAD09B36BB1CF891C0FC78A611" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_930F9D77465382E351C791C0FC7758C4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_B96AAEEAD09B36BB1CF891C0FC78A611" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_930F9D77465382E351C791C0FC7758C4" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringCostAndReserveAxis" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_2BB2FCEC39B1CC78E77091C0FC771890" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_930F9D77465382E351C791C0FC7758C4" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_2BB2FCEC39B1CC78E77091C0FC771890" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_73B4478CA351074C916A91C0FC77879C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_2BB2FCEC39B1CC78E77091C0FC771890" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_73B4478CA351074C916A91C0FC77879C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_73B4478CA351074C916A91C0FC77879C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_2BB2FCEC39B1CC78E77091C0FC771890" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_73B4478CA351074C916A91C0FC77879C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeSeveranceMember" xlink:label="loc_us-gaap_EmployeeSeveranceMember_A6E10F0C55AD6B81EAB691C0FC77495A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_73B4478CA351074C916A91C0FC77879C" xlink:to="loc_us-gaap_EmployeeSeveranceMember_A6E10F0C55AD6B81EAB691C0FC77495A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringPlanAxis" xlink:label="loc_us-gaap_RestructuringPlanAxis_05EDBE9E934E6DEB754C91C0FC77122C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_930F9D77465382E351C791C0FC7758C4" xlink:to="loc_us-gaap_RestructuringPlanAxis_05EDBE9E934E6DEB754C91C0FC77122C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringPlanDomain" xlink:label="loc_us-gaap_RestructuringPlanDomain_FBBB437BC67259E7ECEA91C0FC7839E7_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_05EDBE9E934E6DEB754C91C0FC77122C" xlink:to="loc_us-gaap_RestructuringPlanDomain_FBBB437BC67259E7ECEA91C0FC7839E7_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringPlanDomain" xlink:label="loc_us-gaap_RestructuringPlanDomain_FBBB437BC67259E7ECEA91C0FC7839E7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_05EDBE9E934E6DEB754C91C0FC77122C" xlink:to="loc_us-gaap_RestructuringPlanDomain_FBBB437BC67259E7ECEA91C0FC7839E7" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_RestructuringPlan2016Member" xlink:label="loc_enph_RestructuringPlan2016Member_33BD2061919E56FFAC9B91C0FC787D67" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_FBBB437BC67259E7ECEA91C0FC7839E7" xlink:to="loc_enph_RestructuringPlan2016Member_33BD2061919E56FFAC9B91C0FC787D67" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminatedPeriodPercent" xlink:label="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminatedPeriodPercent_3CB389AD580755E4EAC091C0FC78996A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_B96AAEEAD09B36BB1CF891C0FC78A611" xlink:to="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminatedPeriodPercent_3CB389AD580755E4EAC091C0FC78996A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_29B65410CF3ECEB9AF8591C0FC78B5A0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_B96AAEEAD09B36BB1CF891C0FC78A611" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_29B65410CF3ECEB9AF8591C0FC78B5A0" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_DisposalGroupIncludingDiscontinuedOperationAssetsNet" xlink:label="loc_enph_DisposalGroupIncludingDiscontinuedOperationAssetsNet_08B50A5B87941DE6103B91C0FC78FE93" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_B96AAEEAD09B36BB1CF891C0FC78A611" xlink:to="loc_enph_DisposalGroupIncludingDiscontinuedOperationAssetsNet_08B50A5B87941DE6103B91C0FC78FE93" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_DisposalGroupIncludingDiscontinuedOperationContingentConsiderationAsset" xlink:label="loc_enph_DisposalGroupIncludingDiscontinuedOperationContingentConsiderationAsset_E1EB1F0AF2BEC50D93FB91C0FC7876CB" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_B96AAEEAD09B36BB1CF891C0FC78A611" xlink:to="loc_enph_DisposalGroupIncludingDiscontinuedOperationContingentConsiderationAsset_E1EB1F0AF2BEC50D93FB91C0FC7876CB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GainLossOnSaleOfBusiness" xlink:label="loc_us-gaap_GainLossOnSaleOfBusiness_C23FEDFE27222E76A48991C0FC7818A0" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_B96AAEEAD09B36BB1CF891C0FC78A611" xlink:to="loc_us-gaap_GainLossOnSaleOfBusiness_C23FEDFE27222E76A48991C0FC7818A0" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/RestructuringAndOtherRollforwardDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringCostAndReserveLineItems" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_5C48D264E503DB34EE4183111FD491CD" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_7603B307D524E48B6A4E83111FD2278D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_5C48D264E503DB34EE4183111FD491CD" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_7603B307D524E48B6A4E83111FD2278D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringCostAndReserveAxis" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_559B5508CA06F196DD0083111FD3A4AE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_7603B307D524E48B6A4E83111FD2278D" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_559B5508CA06F196DD0083111FD3A4AE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_A34B3AFC2FBDADCA44DB83111FD37D53_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_559B5508CA06F196DD0083111FD3A4AE" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_A34B3AFC2FBDADCA44DB83111FD37D53_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_A34B3AFC2FBDADCA44DB83111FD37D53" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_559B5508CA06F196DD0083111FD3A4AE" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_A34B3AFC2FBDADCA44DB83111FD37D53" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeSeveranceMember" xlink:label="loc_us-gaap_EmployeeSeveranceMember_AE5E21972223A3C31E8D83111FD3A045" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_A34B3AFC2FBDADCA44DB83111FD37D53" xlink:to="loc_us-gaap_EmployeeSeveranceMember_AE5E21972223A3C31E8D83111FD3A045" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_AssetImpairmentsMember" xlink:label="loc_enph_AssetImpairmentsMember_FCFF316A7BD91F79351B83111FD3A1EC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_A34B3AFC2FBDADCA44DB83111FD37D53" xlink:to="loc_enph_AssetImpairmentsMember_FCFF316A7BD91F79351B83111FD3A1EC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ContractTerminationMember" xlink:label="loc_us-gaap_ContractTerminationMember_2C0CCD9DF654B1EBCB5183111FD3771A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_A34B3AFC2FBDADCA44DB83111FD37D53" xlink:to="loc_us-gaap_ContractTerminationMember_2C0CCD9DF654B1EBCB5183111FD3771A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringPlanAxis" xlink:label="loc_us-gaap_RestructuringPlanAxis_F5F291ECAA0E04307E6783111FD3EB37" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_7603B307D524E48B6A4E83111FD2278D" xlink:to="loc_us-gaap_RestructuringPlanAxis_F5F291ECAA0E04307E6783111FD3EB37" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringPlanDomain" xlink:label="loc_us-gaap_RestructuringPlanDomain_87E75D15F72D9090A50A83111FD3CAA3_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_F5F291ECAA0E04307E6783111FD3EB37" xlink:to="loc_us-gaap_RestructuringPlanDomain_87E75D15F72D9090A50A83111FD3CAA3_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringPlanDomain" xlink:label="loc_us-gaap_RestructuringPlanDomain_87E75D15F72D9090A50A83111FD3CAA3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_F5F291ECAA0E04307E6783111FD3EB37" xlink:to="loc_us-gaap_RestructuringPlanDomain_87E75D15F72D9090A50A83111FD3CAA3" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_RestructuringPlan2016Member" xlink:label="loc_enph_RestructuringPlan2016Member_4CDD75CAB27E672F974083111FD3DB56" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_87E75D15F72D9090A50A83111FD3CAA3" xlink:to="loc_enph_RestructuringPlan2016Member_4CDD75CAB27E672F974083111FD3DB56" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringReserve" xlink:label="loc_us-gaap_RestructuringReserve_546A97D2AD45A667F9BB83111FD400DD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_5C48D264E503DB34EE4183111FD491CD" xlink:to="loc_us-gaap_RestructuringReserve_546A97D2AD45A667F9BB83111FD400DD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringCharges" xlink:label="loc_us-gaap_RestructuringCharges_E3FAEED8EEBFB35CA0BF83111FD47F6D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_5C48D264E503DB34EE4183111FD491CD" xlink:to="loc_us-gaap_RestructuringCharges_E3FAEED8EEBFB35CA0BF83111FD47F6D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsForRestructuring" xlink:label="loc_us-gaap_PaymentsForRestructuring_709168D594003EFE6D8B83111FD4EDAF" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_5C48D264E503DB34EE4183111FD491CD" xlink:to="loc_us-gaap_PaymentsForRestructuring_709168D594003EFE6D8B83111FD4EDAF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringReserveSettledWithoutCash2" xlink:label="loc_us-gaap_RestructuringReserveSettledWithoutCash2_8C82F942664930F9FEC583111FD45958" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_5C48D264E503DB34EE4183111FD491CD" xlink:to="loc_us-gaap_RestructuringReserveSettledWithoutCash2_8C82F942664930F9FEC583111FD45958" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/RestructuringAndOtherScheduleRestructuringChargesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/RestructuringAndOtherTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/SaleOfCommonStock" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/SaleOfCommonStockDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsidiarySaleOfStockLineItems" xlink:label="loc_us-gaap_SubsidiarySaleOfStockLineItems_5325B80E9CA2F63453CAD5403578C942" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable" xlink:label="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_F7C5620586961BE50A10D54035779991" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_5325B80E9CA2F63453CAD5403578C942" xlink:to="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_F7C5620586961BE50A10D54035779991" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_3DFBF6DBE2F6D7D86FD7D541F8D1EB27" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_F7C5620586961BE50A10D54035779991" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_3DFBF6DBE2F6D7D86FD7D541F8D1EB27" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_0515911EBA9FCC44C8A9D541F8D895ED_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_3DFBF6DBE2F6D7D86FD7D541F8D1EB27" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_0515911EBA9FCC44C8A9D541F8D895ED_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_0515911EBA9FCC44C8A9D541F8D895ED" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_3DFBF6DBE2F6D7D86FD7D541F8D1EB27" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_0515911EBA9FCC44C8A9D541F8D895ED" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_A1F02EC116B3C13ECB75D5422DB710EA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_0515911EBA9FCC44C8A9D541F8D895ED" xlink:to="loc_us-gaap_SubsequentEventMember_A1F02EC116B3C13ECB75D5422DB710EA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_4D7634E8265CF6060BB3D5403577DCBB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_F7C5620586961BE50A10D54035779991" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_4D7634E8265CF6060BB3D5403577DCBB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_2EA11A7323D7DFB80691D54035777BDA_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_4D7634E8265CF6060BB3D5403577DCBB" xlink:to="loc_us-gaap_EquityComponentDomain_2EA11A7323D7DFB80691D54035777BDA_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_2EA11A7323D7DFB80691D54035777BDA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_4D7634E8265CF6060BB3D5403577DCBB" xlink:to="loc_us-gaap_EquityComponentDomain_2EA11A7323D7DFB80691D54035777BDA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_821E0B96AB727EFF65A2D5403577C5C9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_2EA11A7323D7DFB80691D54035777BDA" xlink:to="loc_us-gaap_CommonStockMember_821E0B96AB727EFF65A2D5403577C5C9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsidiarySaleOfStockAxis" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_88E5AC7DB331F3098422D54035772FA7" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_F7C5620586961BE50A10D54035779991" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_88E5AC7DB331F3098422D54035772FA7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_37836AF90E83A190D8E7D5403577E8FA_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_88E5AC7DB331F3098422D54035772FA7" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_37836AF90E83A190D8E7D5403577E8FA_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_37836AF90E83A190D8E7D5403577E8FA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_88E5AC7DB331F3098422D54035772FA7" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_37836AF90E83A190D8E7D5403577E8FA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OverAllotmentOptionMember" xlink:label="loc_us-gaap_OverAllotmentOptionMember_4CFB4F256602E13A6145D54035776AA5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_37836AF90E83A190D8E7D5403577E8FA" xlink:to="loc_us-gaap_OverAllotmentOptionMember_4CFB4F256602E13A6145D54035776AA5" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_MarketIssuanceSalesAgreementATMMember" xlink:label="loc_enph_MarketIssuanceSalesAgreementATMMember_281486D609F79B1300A6D5403577E699" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_37836AF90E83A190D8E7D5403577E8FA" xlink:to="loc_enph_MarketIssuanceSalesAgreementATMMember_281486D609F79B1300A6D5403577E699" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_9F192EEACB3DA7FC49EFD5403578EB2B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_5325B80E9CA2F63453CAD5403578C942" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_9F192EEACB3DA7FC49EFD5403578EB2B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SharesIssuedPricePerShare" xlink:label="loc_us-gaap_SharesIssuedPricePerShare_DBB6BB2723B5139B0B13D5403578A141" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_5325B80E9CA2F63453CAD5403578C942" xlink:to="loc_us-gaap_SharesIssuedPricePerShare_DBB6BB2723B5139B0B13D5403578A141" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_AB20F462D863137B2F83D540357898E4" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_5325B80E9CA2F63453CAD5403578C942" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_AB20F462D863137B2F83D540357898E4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercisedNetOfTaxBenefitExpense" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercisedNetOfTaxBenefitExpense_5F9A6364BE91DFD0FA4DD540357808A3" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_5325B80E9CA2F63453CAD5403578C942" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercisedNetOfTaxBenefitExpense_5F9A6364BE91DFD0FA4DD540357808A3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_579A8ECF44C4E439ABEBD5403578A84D" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_5325B80E9CA2F63453CAD5403578C942" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_579A8ECF44C4E439ABEBD5403578A84D" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/SegmentAndGeographicInformation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/SegmentAndGeographicInformationNarrativeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/SegmentAndGeographicInformationSummaryOfLongLivedAssetsByGeographicRegionDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_90C9F910FBF0341448B6C03FAC0824C2" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_65BA96C1D79B5D133DBFC03FAC07DED0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_90C9F910FBF0341448B6C03FAC0824C2" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_65BA96C1D79B5D133DBFC03FAC07DED0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:label="loc_us-gaap_StatementGeographicalAxis_833CDF2E7CF4A5D5C857C03FAC071896" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_65BA96C1D79B5D133DBFC03FAC07DED0" xlink:to="loc_us-gaap_StatementGeographicalAxis_833CDF2E7CF4A5D5C857C03FAC071896" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_40117E9796FA1A1A0CCBC03FAC076F42_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementGeographicalAxis_833CDF2E7CF4A5D5C857C03FAC071896" xlink:to="loc_us-gaap_SegmentGeographicalDomain_40117E9796FA1A1A0CCBC03FAC076F42_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_40117E9796FA1A1A0CCBC03FAC076F42" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementGeographicalAxis_833CDF2E7CF4A5D5C857C03FAC071896" xlink:to="loc_us-gaap_SegmentGeographicalDomain_40117E9796FA1A1A0CCBC03FAC076F42" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/country/2016/country-2016-01-31.xsd#country_US" xlink:label="loc_country_US_A1A8C1530B6863804DD1C03FAC08721A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_40117E9796FA1A1A0CCBC03FAC076F42" xlink:to="loc_country_US_A1A8C1530B6863804DD1C03FAC08721A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/country/2016/country-2016-01-31.xsd#country_CN" xlink:label="loc_country_CN_AA7EFF0B369CACDE7C63C03FAC080956" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_40117E9796FA1A1A0CCBC03FAC076F42" xlink:to="loc_country_CN_AA7EFF0B369CACDE7C63C03FAC080956" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_OtherCountryMember" xlink:label="loc_enph_OtherCountryMember_057EA6375CBA0800122DC03FAC08E0C3" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_40117E9796FA1A1A0CCBC03FAC076F42" xlink:to="loc_enph_OtherCountryMember_057EA6375CBA0800122DC03FAC08E0C3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NoncurrentAssets" xlink:label="loc_us-gaap_NoncurrentAssets_BF7732F6C640542E6414C03FAC08AD9D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_90C9F910FBF0341448B6C03FAC0824C2" xlink:to="loc_us-gaap_NoncurrentAssets_BF7732F6C640542E6414C03FAC08AD9D" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/SegmentAndGeographicInformationSummaryOfNetRevenuesByGeographicRegionDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_C4ABC890028A9648956FC03FAB87EAF1" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_7CC02C07F7DB7C4EC11FC03FAB8771EB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_C4ABC890028A9648956FC03FAB87EAF1" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_7CC02C07F7DB7C4EC11FC03FAB8771EB" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:label="loc_us-gaap_StatementGeographicalAxis_282DF6616A4540B72F0EC03FAB87AA92" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_7CC02C07F7DB7C4EC11FC03FAB8771EB" xlink:to="loc_us-gaap_StatementGeographicalAxis_282DF6616A4540B72F0EC03FAB87AA92" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_BC758F5F510DC3EA6C19C03FAB87F27A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementGeographicalAxis_282DF6616A4540B72F0EC03FAB87AA92" xlink:to="loc_us-gaap_SegmentGeographicalDomain_BC758F5F510DC3EA6C19C03FAB87F27A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_BC758F5F510DC3EA6C19C03FAB87F27A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementGeographicalAxis_282DF6616A4540B72F0EC03FAB87AA92" xlink:to="loc_us-gaap_SegmentGeographicalDomain_BC758F5F510DC3EA6C19C03FAB87F27A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/country/2016/country-2016-01-31.xsd#country_US" xlink:label="loc_country_US_A059008C37D559548E36C03FAB874882" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_BC758F5F510DC3EA6C19C03FAB87F27A" xlink:to="loc_country_US_A059008C37D559548E36C03FAB874882" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_InternationalMember" xlink:label="loc_enph_InternationalMember_03BCD231AB5D90D277AAC03FAB87318D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_BC758F5F510DC3EA6C19C03FAB87F27A" xlink:to="loc_enph_InternationalMember_03BCD231AB5D90D277AAC03FAB87318D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SalesRevenueNet" xlink:label="loc_us-gaap_SalesRevenueNet_B6F1C425BE3B2F592B5CC03FAB885EAD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_C4ABC890028A9648956FC03FAB87EAF1" xlink:to="loc_us-gaap_SalesRevenueNet_B6F1C425BE3B2F592B5CC03FAB885EAD" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/SegmentAndGeographicInformationTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/StockBasedCompensation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/StockBasedCompensationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9AC4EEBE066895A1F2CB91AFA998550C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9AC4EEBE066895A1F2CB91AFA998550C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis_7300C0153602E86068AE91AFA9980F33" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9AC4EEBE066895A1F2CB91AFA998550C" xlink:to="loc_us-gaap_PlanNameAxis_7300C0153602E86068AE91AFA9980F33" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_42294D9ABD87C5C0626491AFA9986AA5_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_7300C0153602E86068AE91AFA9980F33" xlink:to="loc_us-gaap_PlanNameDomain_42294D9ABD87C5C0626491AFA9986AA5_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_42294D9ABD87C5C0626491AFA9986AA5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_7300C0153602E86068AE91AFA9980F33" xlink:to="loc_us-gaap_PlanNameDomain_42294D9ABD87C5C0626491AFA9986AA5" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_TwoThousandSixEquityIncentivePlanMember" xlink:label="loc_enph_TwoThousandSixEquityIncentivePlanMember_59BE2E2393369B57063F91AFA998D4B2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_42294D9ABD87C5C0626491AFA9986AA5" xlink:to="loc_enph_TwoThousandSixEquityIncentivePlanMember_59BE2E2393369B57063F91AFA998D4B2" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_TwoThousandandElevenEquityIncentivePlanMember" xlink:label="loc_enph_TwoThousandandElevenEquityIncentivePlanMember_366D9612F2AF5536FCB891AFA998F658" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_42294D9ABD87C5C0626491AFA9986AA5" xlink:to="loc_enph_TwoThousandandElevenEquityIncentivePlanMember_366D9612F2AF5536FCB891AFA998F658" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_EmployeeStockPurchasePlanEsppMember" xlink:label="loc_enph_EmployeeStockPurchasePlanEsppMember_E3059D5B3537B3383CA691AFA998D176" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_42294D9ABD87C5C0626491AFA9986AA5" xlink:to="loc_enph_EmployeeStockPurchasePlanEsppMember_E3059D5B3537B3383CA691AFA998D176" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AwardDateAxis" xlink:label="loc_us-gaap_AwardDateAxis_1AFBC908D6646B077DCE91AFA998AB0D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9AC4EEBE066895A1F2CB91AFA998550C" xlink:to="loc_us-gaap_AwardDateAxis_1AFBC908D6646B077DCE91AFA998AB0D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AwardDateDomain" xlink:label="loc_us-gaap_AwardDateDomain_3635505C4F51B0DB9A5C91AFA999ECD2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardDateAxis_1AFBC908D6646B077DCE91AFA998AB0D" xlink:to="loc_us-gaap_AwardDateDomain_3635505C4F51B0DB9A5C91AFA999ECD2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AwardDateDomain" xlink:label="loc_us-gaap_AwardDateDomain_3635505C4F51B0DB9A5C91AFA999ECD2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardDateAxis_1AFBC908D6646B077DCE91AFA998AB0D" xlink:to="loc_us-gaap_AwardDateDomain_3635505C4F51B0DB9A5C91AFA999ECD2" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_BeforeAugust12012Member" xlink:label="loc_enph_BeforeAugust12012Member_C42697665D6CC73EEBB391AFA99932B4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_3635505C4F51B0DB9A5C91AFA999ECD2" xlink:to="loc_enph_BeforeAugust12012Member_C42697665D6CC73EEBB391AFA99932B4" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_AfterAugust12012Member" xlink:label="loc_enph_AfterAugust12012Member_B53E2CD69475A5CA8EDD91AFA9994D89" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_3635505C4F51B0DB9A5C91AFA999ECD2" xlink:to="loc_enph_AfterAugust12012Member_B53E2CD69475A5CA8EDD91AFA9994D89" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_196FFDCD1580ADE2ADBF91AFA9993900" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9AC4EEBE066895A1F2CB91AFA998550C" xlink:to="loc_us-gaap_AwardTypeAxis_196FFDCD1580ADE2ADBF91AFA9993900" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_EBEAB54087F8518F006B91AFA999A01A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_196FFDCD1580ADE2ADBF91AFA9993900" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_EBEAB54087F8518F006B91AFA999A01A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_EBEAB54087F8518F006B91AFA999A01A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_196FFDCD1580ADE2ADBF91AFA9993900" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_EBEAB54087F8518F006B91AFA999A01A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_EDF3B80FEC67BF9D180E91AFA9995531" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_EBEAB54087F8518F006B91AFA999A01A" xlink:to="loc_us-gaap_EmployeeStockOptionMember_EDF3B80FEC67BF9D180E91AFA9995531" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_0BA2B1D17FAC377765CF91AFA9996B17" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_EBEAB54087F8518F006B91AFA999A01A" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_0BA2B1D17FAC377765CF91AFA9996B17" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_C62BD9B2D30B1A27AED691AFA999F2B2" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9AC4EEBE066895A1F2CB91AFA998550C" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_C62BD9B2D30B1A27AED691AFA999F2B2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_0652CE222A67F45A763D91AFA999CB54_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_C62BD9B2D30B1A27AED691AFA999F2B2" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_0652CE222A67F45A763D91AFA999CB54_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_0652CE222A67F45A763D91AFA999CB54" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_C62BD9B2D30B1A27AED691AFA999F2B2" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_0652CE222A67F45A763D91AFA999CB54" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_C05CE459845F3176B31891AFA999E5E9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_0652CE222A67F45A763D91AFA999CB54" xlink:to="loc_us-gaap_SubsequentEventMember_C05CE459845F3176B31891AFA999E5E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_4B525EF9452C57E6006791AFA99AD104" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_4B525EF9452C57E6006791AFA99AD104" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_5191C8DB59DD7DC856F791AFA99A4F12" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_5191C8DB59DD7DC856F791AFA99A4F12" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_A0A017204A352A9AE7BF91AFA99A728A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_A0A017204A352A9AE7BF91AFA99A728A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_6C916EE305EC2888D04291AFA99A3C41" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_6C916EE305EC2888D04291AFA99A3C41" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_C7AD2D3C50EE416FAE9991AFA99AA3B8" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_C7AD2D3C50EE416FAE9991AFA99AA3B8" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpirationInYears" xlink:label="loc_enph_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpirationInYears_56DB30C73999C30B3B0691AFA99A3B57" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_enph_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpirationInYears_56DB30C73999C30B3B0691AFA99A3B57" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_IncreaseInCommonStockSharesReservedForFutureIssuancePercentage" xlink:label="loc_enph_IncreaseInCommonStockSharesReservedForFutureIssuancePercentage_E08519F0BCF8B711C73691AFA99A505B" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_enph_IncreaseInCommonStockSharesReservedForFutureIssuancePercentage_E08519F0BCF8B711C73691AFA99A505B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_DBC3D4DA3CE3EEE6FE3491AFA99AA93F" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_DBC3D4DA3CE3EEE6FE3491AFA99AA93F" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_ShareBasedCompensationArrangementByShareBasedPaymentAwardEvergreenShares" xlink:label="loc_enph_ShareBasedCompensationArrangementByShareBasedPaymentAwardEvergreenShares_4809AA74CD3AB9B56FF891AFA99AC91A" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_enph_ShareBasedCompensationArrangementByShareBasedPaymentAwardEvergreenShares_4809AA74CD3AB9B56FF891AFA99AC91A" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_SharebasedCompensationArrangementbySharebasedPaymentAwardIncreaseinNumberofSharesAuthorizedRatio" xlink:label="loc_enph_SharebasedCompensationArrangementbySharebasedPaymentAwardIncreaseinNumberofSharesAuthorizedRatio_304D91B0C3E4FDFEF00391AFA99A9D99" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_enph_SharebasedCompensationArrangementbySharebasedPaymentAwardIncreaseinNumberofSharesAuthorizedRatio_304D91B0C3E4FDFEF00391AFA99A9D99" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_EmployeeStockPurchasePlanNumberOfInterimPurchasePeriods" xlink:label="loc_enph_EmployeeStockPurchasePlanNumberOfInterimPurchasePeriods_2B909461410E2414876691AFA99A7FA4" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_enph_EmployeeStockPurchasePlanNumberOfInterimPurchasePeriods_2B909461410E2414876691AFA99A7FA4" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_GeneralDurationOfEmployeeStockPurchasePlan" xlink:label="loc_enph_GeneralDurationOfEmployeeStockPurchasePlan_FB38A72F75B180F7739A91AFA99A8FB2" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_enph_GeneralDurationOfEmployeeStockPurchasePlan_FB38A72F75B180F7739A91AFA99A8FB2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate_42F9A36CF416F6D2926191AFA99AEFED" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate_42F9A36CF416F6D2926191AFA99AEFED" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_7C0936012220B8BDBB0E91AFA99A8D1F" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_7C0936012220B8BDBB0E91AFA99A8D1F" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_ShareBasedCompensationArrangementByShareBasedPaymentAwardLookBackFeaturePeriod" xlink:label="loc_enph_ShareBasedCompensationArrangementByShareBasedPaymentAwardLookBackFeaturePeriod_41C5920979632D83673391AFA99BDAB7" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_enph_ShareBasedCompensationArrangementByShareBasedPaymentAwardLookBackFeaturePeriod_41C5920979632D83673391AFA99BDAB7" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_EmployeeStockPurchasePlanAdditionalExpenseTriggedByResetFeaturePeriodForRecognition" xlink:label="loc_enph_EmployeeStockPurchasePlanAdditionalExpenseTriggedByResetFeaturePeriodForRecognition_B020496066EEAC480F6291AFA99B6D49" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_enph_EmployeeStockPurchasePlanAdditionalExpenseTriggedByResetFeaturePeriodForRecognition_B020496066EEAC480F6291AFA99B6D49" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_IrsLimitationForEmployeesRightToAcquireClassCommonStockUnderEspp" xlink:label="loc_enph_IrsLimitationForEmployeesRightToAcquireClassCommonStockUnderEspp_60E21AEBC1DCF4C0246D91AFA99BA4F2" xlink:type="locator" />
    <link:definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_enph_IrsLimitationForEmployeesRightToAcquireClassCommonStockUnderEspp_60E21AEBC1DCF4C0246D91AFA99BA4F2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_D89C6FB64B2E4809CAB291AFA99B24C4" xlink:type="locator" />
    <link:definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_D89C6FB64B2E4809CAB291AFA99B24C4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_6C577F987478F8C0326891AFA99B3C56" xlink:type="locator" />
    <link:definitionArc order="19" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_6C577F987478F8C0326891AFA99B3C56" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_3EFC4863A9107421D9C091AFA99BBA3A" xlink:type="locator" />
    <link:definitionArc order="20" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_3EFC4863A9107421D9C091AFA99BBA3A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromExerciseOfStockOptions" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromExerciseOfStockOptions_2C7D49FFE348E1FF522691AFA99B1DE0" xlink:type="locator" />
    <link:definitionArc order="21" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromExerciseOfStockOptions_2C7D49FFE348E1FF522691AFA99B1DE0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_383057BF08598259333591AFA99BA777" xlink:type="locator" />
    <link:definitionArc order="22" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_383057BF08598259333591AFA99BA777" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_8E11357E8432193D53D291AFA99B7EEB" xlink:type="locator" />
    <link:definitionArc order="23" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_8E11357E8432193D53D291AFA99B7EEB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice_737A72480A411A77650291AFA99BB085" xlink:type="locator" />
    <link:definitionArc order="24" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice_737A72480A411A77650291AFA99BB085" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1_7A072050DECA9D7ACC2C91AFA99BA9D4" xlink:type="locator" />
    <link:definitionArc order="25" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1_7A072050DECA9D7ACC2C91AFA99BA9D4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_79F9C7B6EE7E7C5DE33491AFA99BE9D9" xlink:type="locator" />
    <link:definitionArc order="26" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_79F9C7B6EE7E7C5DE33491AFA99BE9D9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions_0E1304D8836423078C5E91AFA99BDD4C" xlink:type="locator" />
    <link:definitionArc order="27" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions_0E1304D8836423078C5E91AFA99BDD4C" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingBasisForDeterminingAggregateIntrinsicValueCompanysSharePricePerShare" xlink:label="loc_enph_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingBasisForDeterminingAggregateIntrinsicValueCompanysSharePricePerShare_AC65D068B039A7E2C28D91AFA99BE21F" xlink:type="locator" />
    <link:definitionArc order="28" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_enph_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingBasisForDeterminingAggregateIntrinsicValueCompanysSharePricePerShare_AC65D068B039A7E2C28D91AFA99BE21F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueVested" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueVested_63C05E675D3192820AF391AFA99B77C1" xlink:type="locator" />
    <link:definitionArc order="29" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueVested_63C05E675D3192820AF391AFA99B77C1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_E249D598A5DD833A759491AFA99B0390" xlink:type="locator" />
    <link:definitionArc order="30" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_E249D598A5DD833A759491AFA99B0390" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsNonvestedIntrinsicValueValue" xlink:label="loc_enph_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsNonvestedIntrinsicValueValue_01B5F34C3C3C6187ACF791AFA99BF808" xlink:type="locator" />
    <link:definitionArc order="31" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94DE1AC5E8473D0B8F4391AFA999634F" xlink:to="loc_enph_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsNonvestedIntrinsicValueValue_01B5F34C3C3C6187ACF791AFA99BF808" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/StockBasedCompensationScheduleOfWeightedAverageAssumptionsUsedToEstimateFairValueOfStockOptionsGrantedDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_C6281D104633B835B05AC03FAB7DE201" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6812E4334B0EB14CF6BFC03FAB7D3925" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_C6281D104633B835B05AC03FAB7DE201" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6812E4334B0EB14CF6BFC03FAB7D3925" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_98C8E0C5CE31E35F66EFC03FAB7DF519" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6812E4334B0EB14CF6BFC03FAB7D3925" xlink:to="loc_us-gaap_AwardTypeAxis_98C8E0C5CE31E35F66EFC03FAB7DF519" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_725CD17418F19313F5E0C03FAB7DF915_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_98C8E0C5CE31E35F66EFC03FAB7DF519" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_725CD17418F19313F5E0C03FAB7DF915_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_725CD17418F19313F5E0C03FAB7DF915" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_98C8E0C5CE31E35F66EFC03FAB7DF519" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_725CD17418F19313F5E0C03FAB7DF915" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_6C57BE96673A910A7A34C03FAB7D0C88" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_725CD17418F19313F5E0C03FAB7DF915" xlink:to="loc_us-gaap_EmployeeStockOptionMember_6C57BE96673A910A7A34C03FAB7D0C88" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_AA43BB60AA6A03FD1CF6C03FAB7D0501" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_C6281D104633B835B05AC03FAB7DE201" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_AA43BB60AA6A03FD1CF6C03FAB7D0501" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_E1C4995DFD80EEDA202BC03FAB7D562E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_AA43BB60AA6A03FD1CF6C03FAB7D0501" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_E1C4995DFD80EEDA202BC03FAB7D562E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_B5850F2EBE8793B60A5CC03FAB7D6A2C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_AA43BB60AA6A03FD1CF6C03FAB7D0501" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_B5850F2EBE8793B60A5CC03FAB7D6A2C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_F1616721CD7B19ADE090C03FAB7DFC7E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_AA43BB60AA6A03FD1CF6C03FAB7D0501" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_F1616721CD7B19ADE090C03FAB7DFC7E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_B806F0E001F537D9375EC03FAB7EE8D5" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_AA43BB60AA6A03FD1CF6C03FAB7D0501" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_B806F0E001F537D9375EC03FAB7EE8D5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_6DB63DB278C593CB6709C03FAB7ED850" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_AA43BB60AA6A03FD1CF6C03FAB7D0501" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_6DB63DB278C593CB6709C03FAB7ED850" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/StockBasedCompensationSummaryOfEsppActivityDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/StockBasedCompensationSummaryOfRestrictedStockUnitActivityDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_519747A16ABAF84569AE91AFA97630F5" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E81118C10A520E765ED491AFA975034A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_519747A16ABAF84569AE91AFA97630F5" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E81118C10A520E765ED491AFA975034A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_5466C4339AEE3BDB5B9491AFA975E89A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E81118C10A520E765ED491AFA975034A" xlink:to="loc_us-gaap_AwardTypeAxis_5466C4339AEE3BDB5B9491AFA975E89A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_76BE5A0DC5B5A76AFB3791AFA9758182_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_5466C4339AEE3BDB5B9491AFA975E89A" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_76BE5A0DC5B5A76AFB3791AFA9758182_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_76BE5A0DC5B5A76AFB3791AFA9758182" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_5466C4339AEE3BDB5B9491AFA975E89A" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_76BE5A0DC5B5A76AFB3791AFA9758182" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_F54728CCB82AC72A196491AFA9767E3D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_76BE5A0DC5B5A76AFB3791AFA9758182" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_F54728CCB82AC72A196491AFA9767E3D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_86C8933FD9B826F8865D91AFA9769DCB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_519747A16ABAF84569AE91AFA97630F5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_86C8933FD9B826F8865D91AFA9769DCB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_F95B8588B2F371F0B80091AFA97642D4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_86C8933FD9B826F8865D91AFA9769DCB" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_F95B8588B2F371F0B80091AFA97642D4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_206E23F34D44B6C4BD7191AFA97639AA" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_86C8933FD9B826F8865D91AFA9769DCB" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_206E23F34D44B6C4BD7191AFA97639AA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_8AD1BAEB5A9D75DD1F6891AFA9761B3A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_86C8933FD9B826F8865D91AFA9769DCB" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_8AD1BAEB5A9D75DD1F6891AFA9761B3A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_B24620AF06781AF1CB1491AFA97612E9" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_86C8933FD9B826F8865D91AFA9769DCB" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_B24620AF06781AF1CB1491AFA97612E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_47EF3A9829E516C74C8891AFA977CC0F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_519747A16ABAF84569AE91AFA97630F5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_47EF3A9829E516C74C8891AFA977CC0F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_68D3F2025FFFBC301C6991AFA9770943" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_47EF3A9829E516C74C8891AFA977CC0F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_68D3F2025FFFBC301C6991AFA9770943" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_5E19617C7DA0C029489891AFA9770CEC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_47EF3A9829E516C74C8891AFA977CC0F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_5E19617C7DA0C029489891AFA9770CEC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_D811F456DB7B333220DE91AFA977AC3A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_47EF3A9829E516C74C8891AFA977CC0F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_D811F456DB7B333220DE91AFA977AC3A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_4A2D73AFABF7F056B91391AFA977421B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_47EF3A9829E516C74C8891AFA977CC0F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_4A2D73AFABF7F056B91391AFA977421B" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/StockBasedCompensationSummaryOfStockBasedCompensationExpenseAssociatedWithEachTypeOfAwardDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_796B2B0E2B07C5A3BFC7C03FAC94A57E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9A333B31CA3F70D68311C03FAC943230" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_796B2B0E2B07C5A3BFC7C03FAC94A57E" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9A333B31CA3F70D68311C03FAC943230" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_4660F1CA3A3CE0571597C03FAC94D48D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9A333B31CA3F70D68311C03FAC943230" xlink:to="loc_us-gaap_AwardTypeAxis_4660F1CA3A3CE0571597C03FAC94D48D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3F70122867B8715027AEC03FAC94E6E6_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_4660F1CA3A3CE0571597C03FAC94D48D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3F70122867B8715027AEC03FAC94E6E6_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3F70122867B8715027AEC03FAC94E6E6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_4660F1CA3A3CE0571597C03FAC94D48D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3F70122867B8715027AEC03FAC94E6E6" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_EmployeeStockOptionsAndRestrictedStockUnitsMember" xlink:label="loc_enph_EmployeeStockOptionsAndRestrictedStockUnitsMember_4CBAFA33CE9079F1B26BC03FAC94AC9B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3F70122867B8715027AEC03FAC94E6E6" xlink:to="loc_enph_EmployeeStockOptionsAndRestrictedStockUnitsMember_4CBAFA33CE9079F1B26BC03FAC94AC9B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeStockMember" xlink:label="loc_us-gaap_EmployeeStockMember_588413C42074FFE76E47C03FAC945236" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3F70122867B8715027AEC03FAC94E6E6" xlink:to="loc_us-gaap_EmployeeStockMember_588413C42074FFE76E47C03FAC945236" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_60E1D91B92B610BFBAA8C03FAC94F25E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_796B2B0E2B07C5A3BFC7C03FAC94A57E" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_60E1D91B92B610BFBAA8C03FAC94F25E" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/StockBasedCompensationSummaryOfStockOptionActivityDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/StockBasedCompensationSummaryOfStockOptionsOutstandingDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_C097DBDFC810850069B8C0EE15D656E7" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_D07B1349391BA0728341C0EE15D55625" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_C097DBDFC810850069B8C0EE15D656E7" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_D07B1349391BA0728341C0EE15D55625" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_B755E36C21E9C63B7CA7C0EE15D6B06C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_D07B1349391BA0728341C0EE15D55625" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_B755E36C21E9C63B7CA7C0EE15D6B06C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_09EFD5237579FA948344C0EE15D6B870_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_B755E36C21E9C63B7CA7C0EE15D6B06C" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_09EFD5237579FA948344C0EE15D6B870_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_09EFD5237579FA948344C0EE15D6B870" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_B755E36C21E9C63B7CA7C0EE15D6B06C" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_09EFD5237579FA948344C0EE15D6B870" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_RangeOneMember" xlink:label="loc_enph_RangeOneMember_67A83B1293D93BE4D10BC0EE15D6C988" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_09EFD5237579FA948344C0EE15D6B870" xlink:to="loc_enph_RangeOneMember_67A83B1293D93BE4D10BC0EE15D6C988" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_RangeTwoMember" xlink:label="loc_enph_RangeTwoMember_2F60457E9CC9F5261C04C0EE15D61934" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_09EFD5237579FA948344C0EE15D6B870" xlink:to="loc_enph_RangeTwoMember_2F60457E9CC9F5261C04C0EE15D61934" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_RangeThreeMember" xlink:label="loc_enph_RangeThreeMember_B597292AFBFD726D3A34C0EE15D6CAB2" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_09EFD5237579FA948344C0EE15D6B870" xlink:to="loc_enph_RangeThreeMember_B597292AFBFD726D3A34C0EE15D6CAB2" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_RangeFourMember" xlink:label="loc_enph_RangeFourMember_A2002E4623D2978CFCB6C0EE15D682BF" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_09EFD5237579FA948344C0EE15D6B870" xlink:to="loc_enph_RangeFourMember_A2002E4623D2978CFCB6C0EE15D682BF" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_RangeFiveMember" xlink:label="loc_enph_RangeFiveMember_7FD916B2C7B80A7A0508C0EE15D696CA" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_09EFD5237579FA948344C0EE15D6B870" xlink:to="loc_enph_RangeFiveMember_7FD916B2C7B80A7A0508C0EE15D696CA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_1179573FB36E05835CACC0EE15D67CEF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_C097DBDFC810850069B8C0EE15D656E7" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_1179573FB36E05835CACC0EE15D67CEF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_3B96FA030B1CAC5242A8C0EE15D61569" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_C097DBDFC810850069B8C0EE15D656E7" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_3B96FA030B1CAC5242A8C0EE15D61569" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_267CF16A448571BCC037C0EE15D6AF27" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_C097DBDFC810850069B8C0EE15D656E7" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_267CF16A448571BCC037C0EE15D6AF27" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2_D9F559B6EEC47C0A6892C0EE15D6B8AB" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_C097DBDFC810850069B8C0EE15D656E7" xlink:to="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2_D9F559B6EEC47C0A6892C0EE15D6B8AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1_4DBAE9B83BDC24E70906C0EE15D6662A" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_C097DBDFC810850069B8C0EE15D656E7" xlink:to="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1_4DBAE9B83BDC24E70906C0EE15D6662A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions_9611F2832FA354C6E4A7C0EE15D63F57" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_C097DBDFC810850069B8C0EE15D656E7" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions_9611F2832FA354C6E4A7C0EE15D63F57" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1_B18253AF6D2BECB59C02C0EE15D601DD" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_C097DBDFC810850069B8C0EE15D656E7" xlink:to="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1_B18253AF6D2BECB59C02C0EE15D601DD" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/StockBasedCompensationSummaryOfTotalStockBasedCompensationExpenseComponentsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_577448145A900CCFCE5FC03FABE0317B" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_38CF3981BD3658FEE773C03FABDF4B9C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_577448145A900CCFCE5FC03FABE0317B" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_38CF3981BD3658FEE773C03FABDF4B9C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_33AD4FAAEAC1F5AF0DD7C03FABDF2F75" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_38CF3981BD3658FEE773C03FABDF4B9C" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_33AD4FAAEAC1F5AF0DD7C03FABDF2F75" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_134785467BA4D48F32BBC03FABDFA3B1_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_33AD4FAAEAC1F5AF0DD7C03FABDF2F75" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_134785467BA4D48F32BBC03FABDFA3B1_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_134785467BA4D48F32BBC03FABDFA3B1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_33AD4FAAEAC1F5AF0DD7C03FABDF2F75" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_134785467BA4D48F32BBC03FABDFA3B1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CostOfSalesMember" xlink:label="loc_us-gaap_CostOfSalesMember_50B51FEBBAD253FEA9FBC03FABE0AD5A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_134785467BA4D48F32BBC03FABDFA3B1" xlink:to="loc_us-gaap_CostOfSalesMember_50B51FEBBAD253FEA9FBC03FABE0AD5A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_BADDFCBC809A68C5A8E5C03FABE0C5F4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_134785467BA4D48F32BBC03FABDFA3B1" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_BADDFCBC809A68C5A8E5C03FABE0C5F4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SellingAndMarketingExpenseMember" xlink:label="loc_us-gaap_SellingAndMarketingExpenseMember_D1DFEE2CE1D4C0A44F09C03FABE042FD" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_134785467BA4D48F32BBC03FABDFA3B1" xlink:to="loc_us-gaap_SellingAndMarketingExpenseMember_D1DFEE2CE1D4C0A44F09C03FABE042FD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_83331C52435B024BEF49C03FABE0CFFB" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_134785467BA4D48F32BBC03FABDFA3B1" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_83331C52435B024BEF49C03FABE0CFFB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_DFFCCE28CE18F3D061B2C03FABE0E6E6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_577448145A900CCFCE5FC03FABE0317B" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_DFFCCE28CE18F3D061B2C03FABE0E6E6" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/StockBasedCompensationTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/SubsequentEvent" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/SubsequentEventDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventLineItems" xlink:label="loc_us-gaap_SubsequentEventLineItems_1EEEBB96F5E16CE4D655C99893DB4AFA" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTable" xlink:label="loc_us-gaap_SubsequentEventTable_1153FEF2769B3D0D4DDDC99893D71D66" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_1EEEBB96F5E16CE4D655C99893DB4AFA" xlink:to="loc_us-gaap_SubsequentEventTable_1153FEF2769B3D0D4DDDC99893D71D66" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_FFDA595028634613AC49C99893D87FFE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_1153FEF2769B3D0D4DDDC99893D71D66" xlink:to="loc_us-gaap_RangeAxis_FFDA595028634613AC49C99893D87FFE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_C0E347F4115459946B7BC99893D89336_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_FFDA595028634613AC49C99893D87FFE" xlink:to="loc_us-gaap_RangeMember_C0E347F4115459946B7BC99893D89336_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_C0E347F4115459946B7BC99893D89336" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_FFDA595028634613AC49C99893D87FFE" xlink:to="loc_us-gaap_RangeMember_C0E347F4115459946B7BC99893D89336" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_EBD3BB57ACFA617DA594C99893D8D580" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_C0E347F4115459946B7BC99893D89336" xlink:to="loc_us-gaap_MinimumMember_EBD3BB57ACFA617DA594C99893D8D580" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_2FAF771CFC000670C790C99893D85430" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_C0E347F4115459946B7BC99893D89336" xlink:to="loc_us-gaap_MaximumMember_2FAF771CFC000670C790C99893D85430" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_259694CB40A78DFF1C52C99893D88ED1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_1153FEF2769B3D0D4DDDC99893D71D66" xlink:to="loc_us-gaap_VariableRateAxis_259694CB40A78DFF1C52C99893D88ED1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_796CFCEA9C992298FD55C99893D98D80_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_259694CB40A78DFF1C52C99893D88ED1" xlink:to="loc_us-gaap_VariableRateDomain_796CFCEA9C992298FD55C99893D98D80_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_796CFCEA9C992298FD55C99893D98D80" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_259694CB40A78DFF1C52C99893D88ED1" xlink:to="loc_us-gaap_VariableRateDomain_796CFCEA9C992298FD55C99893D98D80" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_A19F13CBC67A6F47D113C99893D95F71" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_796CFCEA9C992298FD55C99893D98D80" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_A19F13CBC67A6F47D113C99893D95F71" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityAxis" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_C8C0BC3F933EF9B51F31C99893D91753" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_1153FEF2769B3D0D4DDDC99893D71D66" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_C8C0BC3F933EF9B51F31C99893D91753" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_EE158FFC8542501948A2C99893D9CAE8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_C8C0BC3F933EF9B51F31C99893D91753" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_EE158FFC8542501948A2C99893D9CAE8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_EE158FFC8542501948A2C99893D9CAE8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_C8C0BC3F933EF9B51F31C99893D91753" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_EE158FFC8542501948A2C99893D9CAE8" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_TennenbaumCapitalPartnersLLCMember" xlink:label="loc_enph_TennenbaumCapitalPartnersLLCMember_35462F8596124E9B94A9C99893D96393" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_EE158FFC8542501948A2C99893D9CAE8" xlink:to="loc_enph_TennenbaumCapitalPartnersLLCMember_35462F8596124E9B94A9C99893D96393" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_DebtCovenantTermsAxis" xlink:label="loc_enph_DebtCovenantTermsAxis_AFB385C33573037A011DC99893D98510" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_1153FEF2769B3D0D4DDDC99893D71D66" xlink:to="loc_enph_DebtCovenantTermsAxis_AFB385C33573037A011DC99893D98510" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_DebtCovenantTermsDomain" xlink:label="loc_enph_DebtCovenantTermsDomain_8EF75B781B7CA77593D3C99893DAE129_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_enph_DebtCovenantTermsAxis_AFB385C33573037A011DC99893D98510" xlink:to="loc_enph_DebtCovenantTermsDomain_8EF75B781B7CA77593D3C99893DAE129_default" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_DebtCovenantTermsDomain" xlink:label="loc_enph_DebtCovenantTermsDomain_8EF75B781B7CA77593D3C99893DAE129" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_enph_DebtCovenantTermsAxis_AFB385C33573037A011DC99893D98510" xlink:to="loc_enph_DebtCovenantTermsDomain_8EF75B781B7CA77593D3C99893DAE129" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_ClosingDatetoMarch312018Member" xlink:label="loc_enph_ClosingDatetoMarch312018Member_7CB8CE6D6796A2393734C99893DA6685" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_enph_DebtCovenantTermsDomain_8EF75B781B7CA77593D3C99893DAE129" xlink:to="loc_enph_ClosingDatetoMarch312018Member_7CB8CE6D6796A2393734C99893DA6685" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_April12019andThereafterMember" xlink:label="loc_enph_April12019andThereafterMember_8ABD114306FA4B5A5284C99893DACF71" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_enph_DebtCovenantTermsDomain_8EF75B781B7CA77593D3C99893DAE129" xlink:to="loc_enph_April12019andThereafterMember_8ABD114306FA4B5A5284C99893DACF71" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_7B1722DD6D386F06C5EFC99893DAA175" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_1153FEF2769B3D0D4DDDC99893D71D66" xlink:to="loc_us-gaap_DebtInstrumentAxis_7B1722DD6D386F06C5EFC99893DAA175" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_4B1BAEA4963A051EC027C99893DACFF9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_7B1722DD6D386F06C5EFC99893DAA175" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_4B1BAEA4963A051EC027C99893DACFF9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_4B1BAEA4963A051EC027C99893DACFF9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_7B1722DD6D386F06C5EFC99893DAA175" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_4B1BAEA4963A051EC027C99893DACFF9" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_TermLoanAgreementJuly2016Member" xlink:label="loc_enph_TermLoanAgreementJuly2016Member_1CFE0AF49C6CD8D4BA0CC99893DA217F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4B1BAEA4963A051EC027C99893DACFF9" xlink:to="loc_enph_TermLoanAgreementJuly2016Member_1CFE0AF49C6CD8D4BA0CC99893DA217F" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_AmendedTermLoanAgreementFebruary2017Member" xlink:label="loc_enph_AmendedTermLoanAgreementFebruary2017Member_35F8642D4BF621DE7134C99893DA4E50" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4B1BAEA4963A051EC027C99893DACFF9" xlink:to="loc_enph_AmendedTermLoanAgreementFebruary2017Member_35F8642D4BF621DE7134C99893DA4E50" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_19FF070B48ADFB4536B2C99893DB8B01" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_1153FEF2769B3D0D4DDDC99893D71D66" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_19FF070B48ADFB4536B2C99893DB8B01" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_CE01935825246519621BC99893DB6293_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_19FF070B48ADFB4536B2C99893DB8B01" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_CE01935825246519621BC99893DB6293_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_CE01935825246519621BC99893DB6293" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_19FF070B48ADFB4536B2C99893DB8B01" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_CE01935825246519621BC99893DB6293" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SecuredDebtMember" xlink:label="loc_us-gaap_SecuredDebtMember_BEDD2AEDAA712A14C863C99893DB8A09" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_CE01935825246519621BC99893DB6293" xlink:to="loc_us-gaap_SecuredDebtMember_BEDD2AEDAA712A14C863C99893DB8A09" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_FE2F6D40F14A97253495C99893DBF9CD" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_1153FEF2769B3D0D4DDDC99893D71D66" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_FE2F6D40F14A97253495C99893DBF9CD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_2528F4127FD2AD3194C5C99893DBCFA6_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_FE2F6D40F14A97253495C99893DBF9CD" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_2528F4127FD2AD3194C5C99893DBCFA6_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_2528F4127FD2AD3194C5C99893DBCFA6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_FE2F6D40F14A97253495C99893DBF9CD" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_2528F4127FD2AD3194C5C99893DBCFA6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_86FC213E7A875CC7B9CFC99893DB59C8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_2528F4127FD2AD3194C5C99893DBCFA6" xlink:to="loc_us-gaap_SubsequentEventMember_86FC213E7A875CC7B9CFC99893DB59C8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_5378AC01799AD906A7ABC99893DB2D09" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_1EEEBB96F5E16CE4D655C99893DB4AFA" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_5378AC01799AD906A7ABC99893DB2D09" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_5D17136537B9B3D3DD16C99893E1FF44" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_1EEEBB96F5E16CE4D655C99893DB4AFA" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_5D17136537B9B3D3DD16C99893E1FF44" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityInterestRateDuringPeriod" xlink:label="loc_us-gaap_LineOfCreditFacilityInterestRateDuringPeriod_54FE5DACCB80198CF65EC99893E16CAE" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_1EEEBB96F5E16CE4D655C99893DB4AFA" xlink:to="loc_us-gaap_LineOfCreditFacilityInterestRateDuringPeriod_54FE5DACCB80198CF65EC99893E16CAE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_802986B3160CA01632C9C99893E11349" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_1EEEBB96F5E16CE4D655C99893DB4AFA" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_802986B3160CA01632C9C99893E11349" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_LineofCreditFacilityReductionofInterestRateDuringPeriodPercent" xlink:label="loc_enph_LineofCreditFacilityReductionofInterestRateDuringPeriodPercent_3D3BE53DDC5FA56736ECC99893E1B530" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_1EEEBB96F5E16CE4D655C99893DB4AFA" xlink:to="loc_enph_LineofCreditFacilityReductionofInterestRateDuringPeriodPercent_3D3BE53DDC5FA56736ECC99893E1B530" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_DF16417F0803AED5EC8AC99893E10361" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_1EEEBB96F5E16CE4D655C99893DB4AFA" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_DF16417F0803AED5EC8AC99893E10361" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_LineofCreditFacilityClosingFeePercentage" xlink:label="loc_enph_LineofCreditFacilityClosingFeePercentage_F940C0B7BDFCC8AC6399C99893E1830E" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_1EEEBB96F5E16CE4D655C99893DB4AFA" xlink:to="loc_enph_LineofCreditFacilityClosingFeePercentage_F940C0B7BDFCC8AC6399C99893E1830E" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_LineofCreditFacilityPrepaymentFeePercent" xlink:label="loc_enph_LineofCreditFacilityPrepaymentFeePercent_FFDB2E9E6F352A2EAF81C99893E2A8B0" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_1EEEBB96F5E16CE4D655C99893DB4AFA" xlink:to="loc_enph_LineofCreditFacilityPrepaymentFeePercent_FFDB2E9E6F352A2EAF81C99893E2A8B0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentPeriodicPayment" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPayment_0F495EF2A5604944B3FAC99893E244C2" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_1EEEBB96F5E16CE4D655C99893DB4AFA" xlink:to="loc_us-gaap_DebtInstrumentPeriodicPayment_0F495EF2A5604944B3FAC99893E244C2" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_DebtInstrumentCovenantUnrestrictedCashRequirementMinimum" xlink:label="loc_enph_DebtInstrumentCovenantUnrestrictedCashRequirementMinimum_E4F28A7D4135ECDF809BC99893E202AC" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_1EEEBB96F5E16CE4D655C99893DB4AFA" xlink:to="loc_enph_DebtInstrumentCovenantUnrestrictedCashRequirementMinimum_E4F28A7D4135ECDF809BC99893E202AC" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_DebtInstrumentCovenantLiquidityRatioRequiredMinimum" xlink:label="loc_enph_DebtInstrumentCovenantLiquidityRatioRequiredMinimum_3762E31872DC5A04D59CC99893E25D4F" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_1EEEBB96F5E16CE4D655C99893DB4AFA" xlink:to="loc_enph_DebtInstrumentCovenantLiquidityRatioRequiredMinimum_3762E31872DC5A04D59CC99893E25D4F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_2342FEC7F32FF7350DE8C99893E2C16D" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_1EEEBB96F5E16CE4D655C99893DB4AFA" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_2342FEC7F32FF7350DE8C99893E2C16D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:label="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_97CD875B23C319DD3CEEC99893E21E6C" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_1EEEBB96F5E16CE4D655C99893DB4AFA" xlink:to="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_97CD875B23C319DD3CEEC99893E21E6C" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_ClassOfWarrantOrRightTerm" xlink:label="loc_enph_ClassOfWarrantOrRightTerm_80BE7A89993DB40B33AEC99893E21B11" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_1EEEBB96F5E16CE4D655C99893DB4AFA" xlink:to="loc_enph_ClassOfWarrantOrRightTerm_80BE7A89993DB40B33AEC99893E21B11" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/SummaryOfSignificantAccountingPolicies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/SummaryOfSignificantAccountingPoliciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueOptionQuantitativeDisclosuresLineItems" xlink:label="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueOptionQuantitativeDisclosuresTable" xlink:label="loc_us-gaap_FairValueOptionQuantitativeDisclosuresTable_7A366C90EE2B4654442CD798EE71146B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_us-gaap_FairValueOptionQuantitativeDisclosuresTable_7A366C90EE2B4654442CD798EE71146B" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_9AC0CE8835FAE1F16912D798EE71C488" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresTable_7A366C90EE2B4654442CD798EE71146B" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_9AC0CE8835FAE1F16912D798EE71C488" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_3935AF6C915DAF9D39CDD798EE716CB1_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_9AC0CE8835FAE1F16912D798EE71C488" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_3935AF6C915DAF9D39CDD798EE716CB1_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_3935AF6C915DAF9D39CDD798EE716CB1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_9AC0CE8835FAE1F16912D798EE71C488" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_3935AF6C915DAF9D39CDD798EE716CB1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductConcentrationRiskMember" xlink:label="loc_us-gaap_ProductConcentrationRiskMember_DBDEFEC6ECC99670062CD798EE71AC4C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_3935AF6C915DAF9D39CDD798EE716CB1" xlink:to="loc_us-gaap_ProductConcentrationRiskMember_DBDEFEC6ECC99670062CD798EE71AC4C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_C27B894E4C70728D3C7ED798EE71A09F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresTable_7A366C90EE2B4654442CD798EE71146B" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_C27B894E4C70728D3C7ED798EE71A09F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_2EC98A29BC4FB7298199D798EE71EF40_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_C27B894E4C70728D3C7ED798EE71A09F" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_2EC98A29BC4FB7298199D798EE71EF40_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_2EC98A29BC4FB7298199D798EE71EF40" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_C27B894E4C70728D3C7ED798EE71A09F" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_2EC98A29BC4FB7298199D798EE71EF40" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SalesRevenueNetMember" xlink:label="loc_us-gaap_SalesRevenueNetMember_834635600F4798A0DE8BD798EE715C6B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_2EC98A29BC4FB7298199D798EE71EF40" xlink:to="loc_us-gaap_SalesRevenueNetMember_834635600F4798A0DE8BD798EE715C6B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityAxis" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_73D8076BD997D6EDB144D798EE72217F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresTable_7A366C90EE2B4654442CD798EE71146B" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_73D8076BD997D6EDB144D798EE72217F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_016A9031381D4A55AAA5D798EE729E72_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_73D8076BD997D6EDB144D798EE72217F" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_016A9031381D4A55AAA5D798EE729E72_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_016A9031381D4A55AAA5D798EE729E72" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_73D8076BD997D6EDB144D798EE72217F" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_016A9031381D4A55AAA5D798EE729E72" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_TennenbaumCapitalPartnersLLCMember" xlink:label="loc_enph_TennenbaumCapitalPartnersLLCMember_51E2074D9B3DC038C98ED798EE725D56" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_016A9031381D4A55AAA5D798EE729E72" xlink:to="loc_enph_TennenbaumCapitalPartnersLLCMember_51E2074D9B3DC038C98ED798EE725D56" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_WellsFargoBankMember" xlink:label="loc_enph_WellsFargoBankMember_A574F5C7B04A267BAA88D798EE72B36A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_016A9031381D4A55AAA5D798EE729E72" xlink:to="loc_enph_WellsFargoBankMember_A574F5C7B04A267BAA88D798EE72B36A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_93EB7806F4B1056FD727D798EE720F71" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresTable_7A366C90EE2B4654442CD798EE71146B" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_93EB7806F4B1056FD727D798EE720F71" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_45C37D00562A67453852D798EE72175B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_93EB7806F4B1056FD727D798EE720F71" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_45C37D00562A67453852D798EE72175B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_45C37D00562A67453852D798EE72175B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_93EB7806F4B1056FD727D798EE720F71" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_45C37D00562A67453852D798EE72175B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_58EB8BF6E6E1E218B9B5D798EE72EE51" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_45C37D00562A67453852D798EE72175B" xlink:to="loc_us-gaap_SubsequentEventMember_58EB8BF6E6E1E218B9B5D798EE72EE51" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsidiarySaleOfStockAxis" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_5990C8A0607ACA7F1A4FD798EE720460" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresTable_7A366C90EE2B4654442CD798EE71146B" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_5990C8A0607ACA7F1A4FD798EE720460" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_686DAF5DB8BE45BE0014D798EE72675F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_5990C8A0607ACA7F1A4FD798EE720460" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_686DAF5DB8BE45BE0014D798EE72675F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_686DAF5DB8BE45BE0014D798EE72675F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_5990C8A0607ACA7F1A4FD798EE720460" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_686DAF5DB8BE45BE0014D798EE72675F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OverAllotmentOptionMember" xlink:label="loc_us-gaap_OverAllotmentOptionMember_13DA3F8D34628C1FEBD5D798EE723E59" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_686DAF5DB8BE45BE0014D798EE72675F" xlink:to="loc_us-gaap_OverAllotmentOptionMember_13DA3F8D34628C1FEBD5D798EE723E59" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_MarketIssuanceSalesAgreementATMMember" xlink:label="loc_enph_MarketIssuanceSalesAgreementATMMember_22402361657C159CFCC1D798EE7209AB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_686DAF5DB8BE45BE0014D798EE72675F" xlink:to="loc_enph_MarketIssuanceSalesAgreementATMMember_22402361657C159CFCC1D798EE7209AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PrivatePlacementMember" xlink:label="loc_us-gaap_PrivatePlacementMember_1F616913466419769CD1D798EE72DC48" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_686DAF5DB8BE45BE0014D798EE72675F" xlink:to="loc_us-gaap_PrivatePlacementMember_1F616913466419769CD1D798EE72DC48" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_3A7A00CFF975464E330CD798EE725FD3" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresTable_7A366C90EE2B4654442CD798EE71146B" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_3A7A00CFF975464E330CD798EE725FD3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_9777DDC18C7EBC916132D798EE72BC11_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_3A7A00CFF975464E330CD798EE725FD3" xlink:to="loc_us-gaap_EquityComponentDomain_9777DDC18C7EBC916132D798EE72BC11_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_9777DDC18C7EBC916132D798EE72BC11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_3A7A00CFF975464E330CD798EE725FD3" xlink:to="loc_us-gaap_EquityComponentDomain_9777DDC18C7EBC916132D798EE72BC11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_182D83A23323AD293908D798EE73E7D8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_9777DDC18C7EBC916132D798EE72BC11" xlink:to="loc_us-gaap_CommonStockMember_182D83A23323AD293908D798EE73E7D8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_FC8D678F6A2ED51568C2D798EE73967B" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresTable_7A366C90EE2B4654442CD798EE71146B" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_FC8D678F6A2ED51568C2D798EE73967B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_F5F9E570A9C476DF777BD798EE737880_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_FC8D678F6A2ED51568C2D798EE73967B" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_F5F9E570A9C476DF777BD798EE737880_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_F5F9E570A9C476DF777BD798EE737880" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_FC8D678F6A2ED51568C2D798EE73967B" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_F5F9E570A9C476DF777BD798EE737880" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditMember" xlink:label="loc_us-gaap_LineOfCreditMember_5EED2D15C60E1984723DD798EE73CCE5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_F5F9E570A9C476DF777BD798EE737880" xlink:to="loc_us-gaap_LineOfCreditMember_5EED2D15C60E1984723DD798EE73CCE5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_4DB74CFE4C473282A101D798EE736696" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresTable_7A366C90EE2B4654442CD798EE71146B" xlink:to="loc_us-gaap_CreditFacilityAxis_4DB74CFE4C473282A101D798EE736696" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_0E6024EA66BA12FA1C84D798EE73072C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_4DB74CFE4C473282A101D798EE736696" xlink:to="loc_us-gaap_CreditFacilityDomain_0E6024EA66BA12FA1C84D798EE73072C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_0E6024EA66BA12FA1C84D798EE73072C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_4DB74CFE4C473282A101D798EE736696" xlink:to="loc_us-gaap_CreditFacilityDomain_0E6024EA66BA12FA1C84D798EE73072C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SecuredDebtMember" xlink:label="loc_us-gaap_SecuredDebtMember_225D07B5AB82C8C24C14D798EE736E94" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_0E6024EA66BA12FA1C84D798EE73072C" xlink:to="loc_us-gaap_SecuredDebtMember_225D07B5AB82C8C24C14D798EE736E94" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_A89FCA7E97B241B28122D798EE7311AC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_0E6024EA66BA12FA1C84D798EE73072C" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_A89FCA7E97B241B28122D798EE7311AC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_F1C2B02BBC1FED61DC50D798EE73E8C9" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresTable_7A366C90EE2B4654442CD798EE71146B" xlink:to="loc_us-gaap_DebtInstrumentAxis_F1C2B02BBC1FED61DC50D798EE73E8C9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_EF9609E2934669E31099D798EE78BEC0_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_F1C2B02BBC1FED61DC50D798EE73E8C9" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_EF9609E2934669E31099D798EE78BEC0_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_EF9609E2934669E31099D798EE78BEC0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_F1C2B02BBC1FED61DC50D798EE73E8C9" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_EF9609E2934669E31099D798EE78BEC0" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_TennenbaumCapitalPartnersLLCTermLoanAgreementMember" xlink:label="loc_enph_TennenbaumCapitalPartnersLLCTermLoanAgreementMember_D6655DAF07EE4D4A3E47D798EE78AD31" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_EF9609E2934669E31099D798EE78BEC0" xlink:to="loc_enph_TennenbaumCapitalPartnersLLCTermLoanAgreementMember_D6655DAF07EE4D4A3E47D798EE78AD31" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_AmendedTennenbaumCapitalPartnersLLCAgreementMember" xlink:label="loc_enph_AmendedTennenbaumCapitalPartnersLLCAgreementMember_52645DE985B4015FA2B9D798EE78C9FD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_EF9609E2934669E31099D798EE78BEC0" xlink:to="loc_enph_AmendedTennenbaumCapitalPartnersLLCAgreementMember_52645DE985B4015FA2B9D798EE78C9FD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_6C128B736714A5A7750BD798EE7817CE" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresTable_7A366C90EE2B4654442CD798EE71146B" xlink:to="loc_us-gaap_RangeAxis_6C128B736714A5A7750BD798EE7817CE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_F73CD8CF17C200545C51D798EE796BAB_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_6C128B736714A5A7750BD798EE7817CE" xlink:to="loc_us-gaap_RangeMember_F73CD8CF17C200545C51D798EE796BAB_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_F73CD8CF17C200545C51D798EE796BAB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_6C128B736714A5A7750BD798EE7817CE" xlink:to="loc_us-gaap_RangeMember_F73CD8CF17C200545C51D798EE796BAB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_1ABE9914804F9F603E89D798EE79B6EA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_F73CD8CF17C200545C51D798EE796BAB" xlink:to="loc_us-gaap_MinimumMember_1ABE9914804F9F603E89D798EE79B6EA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_044E4CEF09BAD3E16B4FD798EE791A11" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_F73CD8CF17C200545C51D798EE796BAB" xlink:to="loc_us-gaap_MaximumMember_044E4CEF09BAD3E16B4FD798EE791A11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductOrServiceAxis" xlink:label="loc_us-gaap_ProductOrServiceAxis_4C7D4221143EC0169430D798EE79D55E" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresTable_7A366C90EE2B4654442CD798EE71146B" xlink:to="loc_us-gaap_ProductOrServiceAxis_4C7D4221143EC0169430D798EE79D55E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductsAndServicesDomain" xlink:label="loc_us-gaap_ProductsAndServicesDomain_589A201B0C440AAB86B5D798EE79DD65_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ProductOrServiceAxis_4C7D4221143EC0169430D798EE79D55E" xlink:to="loc_us-gaap_ProductsAndServicesDomain_589A201B0C440AAB86B5D798EE79DD65_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductsAndServicesDomain" xlink:label="loc_us-gaap_ProductsAndServicesDomain_589A201B0C440AAB86B5D798EE79DD65" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ProductOrServiceAxis_4C7D4221143EC0169430D798EE79D55E" xlink:to="loc_us-gaap_ProductsAndServicesDomain_589A201B0C440AAB86B5D798EE79DD65" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_EnlightenWebBasedMonitoringServiceMember" xlink:label="loc_enph_EnlightenWebBasedMonitoringServiceMember_E6C2E4CC388CC459E814D798EE791DF9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductsAndServicesDomain_589A201B0C440AAB86B5D798EE79DD65" xlink:to="loc_enph_EnlightenWebBasedMonitoringServiceMember_E6C2E4CC388CC459E814D798EE791DF9" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_EnvoyCommunicationsGatewayDeviceAndEnlightenWebBasedMonitoringServiceMember" xlink:label="loc_enph_EnvoyCommunicationsGatewayDeviceAndEnlightenWebBasedMonitoringServiceMember_B45BB90E72C5ACAAA7E5D798EE798775" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductsAndServicesDomain_589A201B0C440AAB86B5D798EE79DD65" xlink:to="loc_enph_EnvoyCommunicationsGatewayDeviceAndEnlightenWebBasedMonitoringServiceMember_B45BB90E72C5ACAAA7E5D798EE798775" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_FirstAndSecondGenerationMember" xlink:label="loc_enph_FirstAndSecondGenerationMember_53548BB6DB093477AF2DD798EE794990" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductsAndServicesDomain_589A201B0C440AAB86B5D798EE79DD65" xlink:to="loc_enph_FirstAndSecondGenerationMember_53548BB6DB093477AF2DD798EE794990" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_ThirdandFourthGenerationMember" xlink:label="loc_enph_ThirdandFourthGenerationMember_511C66464F864DC9CE0BD798EE793167" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductsAndServicesDomain_589A201B0C440AAB86B5D798EE79DD65" xlink:to="loc_enph_ThirdandFourthGenerationMember_511C66464F864DC9CE0BD798EE793167" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_EnvoyCommunicationsGatewayMember" xlink:label="loc_enph_EnvoyCommunicationsGatewayMember_11E3113BC4AD71C35E7BD798EE79D65F" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductsAndServicesDomain_589A201B0C440AAB86B5D798EE79DD65" xlink:to="loc_enph_EnvoyCommunicationsGatewayMember_11E3113BC4AD71C35E7BD798EE79D65F" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_ACBatteryStorageSolutionMember" xlink:label="loc_enph_ACBatteryStorageSolutionMember_678CE795116457E719AFD798EE79F3AB" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductsAndServicesDomain_589A201B0C440AAB86B5D798EE79DD65" xlink:to="loc_enph_ACBatteryStorageSolutionMember_678CE795116457E719AFD798EE79F3AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_9CDD89C07201EEBBB4D4D798EE7AAA34" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_9CDD89C07201EEBBB4D4D798EE7AAA34" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_WorkingCapital" xlink:label="loc_enph_WorkingCapital_A5F7B8180E3B87B29692D798EE7A15A2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_enph_WorkingCapital_A5F7B8180E3B87B29692D798EE7A15A2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_EC419F597F38619CA3CED798EE7AFE37" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_EC419F597F38619CA3CED798EE7AFE37" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_F9D8268A91731BE6AB45D798EE7AD26F" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_F9D8268A91731BE6AB45D798EE7AD26F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_72D0AED26B1AD62E9246D798EE7A624D" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_72D0AED26B1AD62E9246D798EE7A624D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_55E187A6EBBDEA85F805D798EE7A8E93" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_55E187A6EBBDEA85F805D798EE7A8E93" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_523DA714B567C351BA63D798EE7AC5A7" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_523DA714B567C351BA63D798EE7AC5A7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RepaymentsOfLinesOfCredit" xlink:label="loc_us-gaap_RepaymentsOfLinesOfCredit_4C64867B60C5A4FC0BB8D798EE7A5875" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_us-gaap_RepaymentsOfLinesOfCredit_4C64867B60C5A4FC0BB8D798EE7A5875" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EffectOnFutureEarningsOffsetAmount" xlink:label="loc_us-gaap_EffectOnFutureEarningsOffsetAmount_563A9BCCDAF09624EDD6D798EE7A41D3" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_us-gaap_EffectOnFutureEarningsOffsetAmount_563A9BCCDAF09624EDD6D798EE7A41D3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_9EF845E21F237BAD0E69D798EE7AC706" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_9EF845E21F237BAD0E69D798EE7AC706" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_RevenueRecognitionMultipleDeliverableArrangementsNumberOfDeliverables" xlink:label="loc_enph_RevenueRecognitionMultipleDeliverableArrangementsNumberOfDeliverables_871D22D79C1CC875858DD798EE7ACFDE" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_enph_RevenueRecognitionMultipleDeliverableArrangementsNumberOfDeliverables_871D22D79C1CC875858DD798EE7ACFDE" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_RevenueRecognitionRecognitionPeriod" xlink:label="loc_enph_RevenueRecognitionRecognitionPeriod_69733DB468CEB74C18B8D798EE7A4F3C" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_enph_RevenueRecognitionRecognitionPeriod_69733DB468CEB74C18B8D798EE7A4F3C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivable" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_4926CA2F1A3C6A64B6F8D798EE7BF955" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_4926CA2F1A3C6A64B6F8D798EE7BF955" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_2925D051F5B0AA64EB95D798EE7BE8E9" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_2925D051F5B0AA64EB95D798EE7BE8E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AssetImpairmentCharges" xlink:label="loc_us-gaap_AssetImpairmentCharges_A8BFAF6FC03C90435120D798EE7B0864" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_us-gaap_AssetImpairmentCharges_A8BFAF6FC03C90435120D798EE7B0864" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringCostsAndAssetImpairmentCharges" xlink:label="loc_us-gaap_RestructuringCostsAndAssetImpairmentCharges_0E36E940FBBA55975D99D798EE7BDF80" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_us-gaap_RestructuringCostsAndAssetImpairmentCharges_0E36E940FBBA55975D99D798EE7BDF80" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillImpairmentLoss" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_E3AE9A90294246CEB90BD798EE7B4CFB" xlink:type="locator" />
    <link:definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_E3AE9A90294246CEB90BD798EE7B4CFB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_1B07B4725CBA165FFF57D798EE7B1F6B" xlink:type="locator" />
    <link:definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_1B07B4725CBA165FFF57D798EE7B1F6B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill_27EFC912CD2899CBAEB9D798EE7B5C7B" xlink:type="locator" />
    <link:definitionArc order="19" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill_27EFC912CD2899CBAEB9D798EE7B5C7B" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_ProductWarrantyTerm" xlink:label="loc_enph_ProductWarrantyTerm_E8BFAA9D4050256F9DD4D798EE7BA14B" xlink:type="locator" />
    <link:definitionArc order="20" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_enph_ProductWarrantyTerm_E8BFAA9D4050256F9DD4D798EE7BA14B" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_ProductWarrantyEstimatedFailureRatePeriodBetweenProductSaleandInstallation" xlink:label="loc_enph_ProductWarrantyEstimatedFailureRatePeriodBetweenProductSaleandInstallation_BEA7247CA8AB2CB7685DD798EE7BE3BA" xlink:type="locator" />
    <link:definitionArc order="21" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_enph_ProductWarrantyEstimatedFailureRatePeriodBetweenProductSaleandInstallation_BEA7247CA8AB2CB7685DD798EE7BE3BA" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_ProductWarrantyEstimatedFailureRatePeriodBetweenProductSaleandStartofMonitoring" xlink:label="loc_enph_ProductWarrantyEstimatedFailureRatePeriodBetweenProductSaleandStartofMonitoring_57D21C67D8F666D52101D798EE7BC6AF" xlink:type="locator" />
    <link:definitionArc order="22" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_enph_ProductWarrantyEstimatedFailureRatePeriodBetweenProductSaleandStartofMonitoring_57D21C67D8F666D52101D798EE7BC6AF" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_ProductWarrantyEstimatedReplacementCostNumberOfFactors" xlink:label="loc_enph_ProductWarrantyEstimatedReplacementCostNumberOfFactors_2A519BEE5EAF9BCB2ED1D798EE7C9CE2" xlink:type="locator" />
    <link:definitionArc order="23" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_enph_ProductWarrantyEstimatedReplacementCostNumberOfFactors_2A519BEE5EAF9BCB2ED1D798EE7C9CE2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_A6BE598598AE10A50184D798EE7CCE31" xlink:type="locator" />
    <link:definitionArc order="24" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_A6BE598598AE10A50184D798EE7CCE31" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_2C8ABF300C550E233B03D798EE7C0ED0" xlink:type="locator" />
    <link:definitionArc order="25" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_DBD5A670A1C4468EF466D798EE7A601D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_2C8ABF300C550E233B03D798EE7C0ED0" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/SummaryOfSignificantAccountingPoliciesScheduleOfActivityInAllowanceForDoubtfulAccountsDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/SummaryOfSignificantAccountingPoliciesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/WarrantyObligations" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/WarrantyObligationsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductLiabilityContingencyLineItems" xlink:label="loc_us-gaap_ProductLiabilityContingencyLineItems_7BDA70E5BBBFA039499183112011CFD1" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductLiabilityContingencyTable" xlink:label="loc_us-gaap_ProductLiabilityContingencyTable_93DC649E40CD45C79E0483112010AF7B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ProductLiabilityContingencyLineItems_7BDA70E5BBBFA039499183112011CFD1" xlink:to="loc_us-gaap_ProductLiabilityContingencyTable_93DC649E40CD45C79E0483112010AF7B" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductOrServiceAxis" xlink:label="loc_us-gaap_ProductOrServiceAxis_715FC92B25ACC2247220831120109175" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ProductLiabilityContingencyTable_93DC649E40CD45C79E0483112010AF7B" xlink:to="loc_us-gaap_ProductOrServiceAxis_715FC92B25ACC2247220831120109175" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductsAndServicesDomain" xlink:label="loc_us-gaap_ProductsAndServicesDomain_62FB6DD7575B9827079583112010B668_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ProductOrServiceAxis_715FC92B25ACC2247220831120109175" xlink:to="loc_us-gaap_ProductsAndServicesDomain_62FB6DD7575B9827079583112010B668_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductsAndServicesDomain" xlink:label="loc_us-gaap_ProductsAndServicesDomain_62FB6DD7575B9827079583112010B668" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ProductOrServiceAxis_715FC92B25ACC2247220831120109175" xlink:to="loc_us-gaap_ProductsAndServicesDomain_62FB6DD7575B9827079583112010B668" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_SecondGenerationProductsMember" xlink:label="loc_enph_SecondGenerationProductsMember_9074E7E0E188FFADE6088311201005B7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductsAndServicesDomain_62FB6DD7575B9827079583112010B668" xlink:to="loc_enph_SecondGenerationProductsMember_9074E7E0E188FFADE6088311201005B7" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_ThirdGenerationProductsMember" xlink:label="loc_enph_ThirdGenerationProductsMember_77F68F4834B54075F49C8311201061E1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductsAndServicesDomain_62FB6DD7575B9827079583112010B668" xlink:to="loc_enph_ThirdGenerationProductsMember_77F68F4834B54075F49C8311201061E1" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_FourthGenerationMember" xlink:label="loc_enph_FourthGenerationMember_5A46F8D3F2FD54E79AA683112010D4DE" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductsAndServicesDomain_62FB6DD7575B9827079583112010B668" xlink:to="loc_enph_FourthGenerationMember_5A46F8D3F2FD54E79AA683112010D4DE" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_FourthAndFifthGenerationMember" xlink:label="loc_enph_FourthAndFifthGenerationMember_F5E8C28C8E3553048895831120113469" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductsAndServicesDomain_62FB6DD7575B9827079583112010B668" xlink:to="loc_enph_FourthAndFifthGenerationMember_F5E8C28C8E3553048895831120113469" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_AllProductGenerationsMember" xlink:label="loc_enph_AllProductGenerationsMember_063AADECB68B60856AE3831120112F15" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductsAndServicesDomain_62FB6DD7575B9827079583112010B668" xlink:to="loc_enph_AllProductGenerationsMember_063AADECB68B60856AE3831120112F15" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_WarrantyVariableAxis" xlink:label="loc_enph_WarrantyVariableAxis_881A338FE51E428FFB75831120118C41" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ProductLiabilityContingencyTable_93DC649E40CD45C79E0483112010AF7B" xlink:to="loc_enph_WarrantyVariableAxis_881A338FE51E428FFB75831120118C41" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_WarrantyVariableDomain" xlink:label="loc_enph_WarrantyVariableDomain_6F67A75A8FFEBFB7FC81831120115C88_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_enph_WarrantyVariableAxis_881A338FE51E428FFB75831120118C41" xlink:to="loc_enph_WarrantyVariableDomain_6F67A75A8FFEBFB7FC81831120115C88_default" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_WarrantyVariableDomain" xlink:label="loc_enph_WarrantyVariableDomain_6F67A75A8FFEBFB7FC81831120115C88" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_enph_WarrantyVariableAxis_881A338FE51E428FFB75831120118C41" xlink:to="loc_enph_WarrantyVariableDomain_6F67A75A8FFEBFB7FC81831120115C88" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_ReplacementCostMember" xlink:label="loc_enph_ReplacementCostMember_404B5764C2DD1A6750D7831120119A1F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_enph_WarrantyVariableDomain_6F67A75A8FFEBFB7FC81831120115C88" xlink:to="loc_enph_ReplacementCostMember_404B5764C2DD1A6750D7831120119A1F" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_LaborReimbursementCostMember" xlink:label="loc_enph_LaborReimbursementCostMember_D9E185E0078E6BE0D4B78311201105B8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_enph_WarrantyVariableDomain_6F67A75A8FFEBFB7FC81831120115C88" xlink:to="loc_enph_LaborReimbursementCostMember_D9E185E0078E6BE0D4B78311201105B8" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_FailureRateMember" xlink:label="loc_enph_FailureRateMember_8E4CD583B0D9B6266469831120116C69" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_enph_WarrantyVariableDomain_6F67A75A8FFEBFB7FC81831120115C88" xlink:to="loc_enph_FailureRateMember_8E4CD583B0D9B6266469831120116C69" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_NumberofUnitsSold" xlink:label="loc_enph_NumberofUnitsSold_13230F0794E1289E1D45831120110742" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductLiabilityContingencyLineItems_7BDA70E5BBBFA039499183112011CFD1" xlink:to="loc_enph_NumberofUnitsSold_13230F0794E1289E1D45831120110742" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_ProductWarrantyExpenseIncreaseDecreaseinWarrantyExpenseDuetoChangesinWarrantyVariables" xlink:label="loc_enph_ProductWarrantyExpenseIncreaseDecreaseinWarrantyExpenseDuetoChangesinWarrantyVariables_13F1E0F750CBF0CFBA8B831120114804" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductLiabilityContingencyLineItems_7BDA70E5BBBFA039499183112011CFD1" xlink:to="loc_enph_ProductWarrantyExpenseIncreaseDecreaseinWarrantyExpenseDuetoChangesinWarrantyVariables_13F1E0F750CBF0CFBA8B831120114804" xlink:type="arc" />
    <link:loc xlink:href="enph-20161231.xsd#enph_ProductWarrantyExpenseIncreaseDecreaseinWarrantyExpenseDuetoChangesinWarrantyVariablesNet" xlink:label="loc_enph_ProductWarrantyExpenseIncreaseDecreaseinWarrantyExpenseDuetoChangesinWarrantyVariablesNet_31EDE20A1686740B25D883112011913F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductLiabilityContingencyLineItems_7BDA70E5BBBFA039499183112011CFD1" xlink:to="loc_enph_ProductWarrantyExpenseIncreaseDecreaseinWarrantyExpenseDuetoChangesinWarrantyVariablesNet_31EDE20A1686740B25D883112011913F" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://enphase.com/role/WarrantyObligationsSummaryOfWarrantyActivityDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://enphase.com/role/WarrantyObligationsTables" xlink:type="extended" />
</link:linkbase>
