光伏组件PID测试

Insertpicturehere10x17cmTÜVSÜDGreaterChinaTÜVSÜD:PartnershipaddsvaluePotentialInducedDegradation(PID)ServiceIntroduction()(PID)TÜVSÜDContentPotentialInducedDegradation(PID)BackgroundIntroductionPID1StandardsrelatedtoPotentialInducedDegradationPIDPID3WhatweinspectinPotentialInducedDegradationPID27May20122Presentongoingtestatlab4Q&A5TÜVSÜD5May2009ThefutureisbrightSlide3PotentialInducedDegradation(PID)BackgroundIntroductionWhatisPIDPIDPotential-induceddegradation(PID)ofcrystallinesiliconsolarcellswasfirstobservedbySunpowerin2005Itwasfoundthatleakagecurrentthroughthefrontglassandencapsulationmaterialleadstoaccumulationoftrappednegativechargeonatthesurfaceofthecells.Thesurfacepassivationprovidedbythefrontsurfacefieldofthesecellsdegraded.Thefillfactor(FF),short-circuitcurrentdensity(Jsc)andopen-circuitvoltage(Voc)weresignificantlyreduced.PIDSunpower2005FFJscVocIn2010,NRELandSolondemonstratedthatPIDisafundamentalriskwheneverstate-of-the-artp-typecrystallinesiliconsolarcellsareusedinstandardmodulesathighnegativebias2010NRELSolonpPIDTÜVSÜD1.1ThreedegradationmodesofPIDPID5May2009ThefutureisbrightSlide4IonicmotioninthepackagingoftheactivelayerleadstoaccumulationofchargeorchargedionsoverthesemiconductorsurfaceChargeinfluencessurfacefieldofsemiconductoractivelayer.Inseverecases,accumulationofmobileionssuchasNaintheglassleadstodelamination.Ionicmotionalsotakesplacewithintheactivelayer,degradingsemiconductorjunctionpropertiesandcausingshuntsUsuallyinthepresenceofhumidityinthepackaging,electrolyticcorrosionoccursandmacroscopictransportofionizedconductormetalisobserved.TÜVSÜD5May2009ThefutureisbrightSlide5ReportedbyBPSolar…a-Simodules-600Vbias12mo.inthefieldSodiumionsmigratingtotheTCO/glassinterfacecausesdelaminationoftheTCO,electrochemicalcorrosion/TCOTCOMode11-NaTCOTÜVSÜD5May2009ThefutureisbrightSlide6N-type:Multic-Si:Sunpowerin2005Positivelybiasedstringscauseleakagecurrentof+carriersthroughglasstogroundthroughgroundedframe,leavingnegativechargeoncellsurface,thusdegradingeffectivenessofn+frontfieldofthen+/nlayer.Minorityn+carriers(holes)recombineatfrontsurfaceleadingtodegradedcellperformancen+/nn+n+Mode11-NaTÜVSÜD5May2009ThefutureisbrightSlide7Ionicmotionalsotakesplacewithintheactivelayer,degradingsemiconductorjunctionpropertiesandcausingshuntsMode22P-nFig.Ionicmotionwithinactivelayerofthinfilmdevicesalsoactivep-np-nTÜVSÜD5May2009ThefutureisbrightSlide8Mode33-CorrosionofgridlinesandSi-gridinterfaceleadingtohigherseriesresistanceevidentvisibly,inelectroluminescence,andI-VcurvesELI-VSiCorrosionandionictransportatbusribbonstowardframe(positivestring)TÜVSÜD1.2ThecauseofPIDPID5May2009ThefutureisbrightSlide9Externalpotential:Hot&humidconditionscombinedwithsystemvoltagebiasduetoPVinvertergroundingofthearrays.Internalpotential:ThecauseofPIDthreedifferentlevels-system,panelandcell.:PIDTÜVSÜD5May2009ThefutureisbrightSlide10Theindividualmodulesareconnectedtostringstoincreasesystemvoltage.Themetallicframesofthemodulesareusuallygrounded,thisleadtoavoltagebiasoftheindividualmoduleswithrespecttotheirframes.Whateffectsvoltagebias1.Theinvertertypeandgroundingofinverterusedforcouplingthedcoutputtotheacgrid.2.Thepositionofthemoduleinthestring.1.2.1SystemlevelTÜVSÜD5May2009ThefutureisbrightSlide11Dependingontheconfigurationofthegroundingthepotentialofacelltowardsgroundisnegativeorpositive.Inthelattercaseonepartofthestringhasanegativeandtheotherapositivepotentialtowardsground.PIDPIDFig.Stringpotential,threegroudingschemesPV+/PV-andnogrounding(floatingpotential)ThepositionofthemoduleinthestringTÜVSÜD5May2009ThefutureisbrightSlide12ThePV-negativepoleofthestringisgroundedPIDcanbeeffectivelyprevented.PVPIDNegativegroundingoftransformerbasedinvertersortheinherentnegativegroundingofsometransformerlessinverterseliminatePID.PIDInverterTÜVSÜD5May2009ThefutureisbrightSlide131.2.2PanellevelEnvironmentalfactorssuchashumidityandtemperatureinfluenceleakagecurrentsbetweengroundandcell.Theinteractionofencapsulationmaterial,backsheetfoil,glass,andframeisresultingincertainleakagecurrentpaths.AdditionallymaterialpropertiesproductionprocessesandpanellayoutdoplayarolefortheHV-durabilityofpanels.Fig.PIDsetup(left)andleakagecurrents(right).PIDTÜVSÜD5May2009ThefutureisbrightSlide14EncapsulationmaterialFig.leakagecurrentfortwopanelswithdifferentENCmaterialDuringatemperaturerampfrom-20to48with1000Vappliedvoltage(RH50%)EVA1000VRH50%-2048OnpanellevelthepropertiesoftheencapsulationmaterialdeterminetheheightofleakagecurrentsthatcanincaseofpronesolarcellsleadtoPID.PIDFig.PIDcomparisonofthreedifferentENCmaterialsinpanelswithpronesolarcells.EVAPIDTÜVSÜD5May2009ThefutureisbrightSlide15Howtominimizetheleakagecurrent?GlassForreductionoftheleakagecurrentspecialglassesnotbelongingtothesoda-limefamilyareneededwhicharemuchmoreexpensive.EncapsulationmaterialsUsingEncapsulationmaterialsfeaturinghighervolumeresistivitybutthepriceofthesefoilsandtheiropticalperformance(refractiveindexandextinctioncoefficient)mustbeconsidered.1.2.2PanellevelTÜVSÜD5May2009ThefutureisbrightSlide161.2.3