NREL Considerations for a Standardized Test for PID of Cristalline Silicon PV Modules

8/14/2019 NREL Considerationsfora StandardizedTestforPID of Cristalline Silicon PV Modules

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NRELisanationallaboratoryoftheU.S.DepartmentofEnergy,OfficeofEnergyEfficiencyandRenewableEnergy,operatedby theAllianceforSustainableEnergy,LLC.

Considerationsfora StandardizedTestfor

PotentialInducedDegradationofCrystalline

Silicon PVModules

2012PVMRW

Peter

Hacke

February29,2012

NREL/PR-5200-54581


2/30

2

Majorcontributionsfrom:

SteveGlick

Ryan

SmithMikeKempe

Steve

JohnstonJoelPankow

SarahKurtz

KentTerwilliger

Dirk

JordanSteveRummel

Alan

AnderbergBillSekulic


3/30

3

Motivation

Overthepastdecade,therehavebeenobservationsofmodule

degradationandpowerlossbecauseofthestressthatsystem

voltagebiasexerts.

Moresensitive

modules

Highersystemvoltage

Thisresultsinpartfromqualificationtestsandstandardsnot

adequatelyevaluatingforthedurabilityofmodulestothelongterm

effectsof

high

voltage

bias

that

they

experience

in

fielded

arrays.

Thistalkdealswithfactorsforconsideration,progress,and

informationstillneededforastandardizedtestfordegradationdue

tosystemvoltagestress.

Ohno!

our

modules

are

down

40%,

wethinkitispotentialinduceddegradationanonymousmodulemanufacturer,2010


4/30

4

Timelineforsystemvoltagedurability

Needfor

abetter

standard

for

system

voltage

durability

brought

up

severaltimesinthelastdecades,butdidnotgettraction.Lackoffield

data,proposedtestsoverlyharsh.

IbroughtthisupagainintheFall2010WorkingGroup2(WG2)meeting

(Kln)andgotasmallworkingtogether,butmostpeoplewereinthe

processofgettingexperienceaboutsystemvoltageeffects.

Spring2011WG2meeting(Shanghai),indicationsofincreasedurgency

forastandard,assembledmorepeopleforthistaskteam.

Fall2011WG2meeting(Montreal),presentedaninitialdraftfor

comments.

Presentday


5/30

5

Goalsforastandard twosteps

1. Standalone

test

(new

standard):

Systemvoltagedurabilitytestforcrystallinesiliconmodules

design

qualification

and

type

approval,

submittedasaNewWorkItemProposaltoIEC,Dec.

2011.

2. Incorporatetest

into

IEC

61215

Seektoincorporateabovestandalonetestwithany

necessarysupplementswithinIEC61215

addtestafterclause10.13,DampHeatTest1000hunderconsideration.


6/30

6

Designstandardforaclimate:Kppen climateclassification

GROUPC:Temperate/mesothermal climates

Maritime/oceanic climates: (Cfb, Cwb, Cfc)

Humid subtropical climates (Cfa, Cwa)

Consider for standard: Humid subtropical,

and Humid Oceanic.

Need to design for the market. More

stressful environments exist, and thatshould be noted in the eventual standard.


7/307

ExperimentalOverview

1) HV Test bed in Florida USA 2 module types fielded in February 2011

2) Chamber testing of the same 2 module designstested in Florida

85% RH; 85C, 60C, 50C

Pmax

vs t

3) Comparison of failure rates for determination of

acceleration factors and failure mechanisms for

input into standardized test


8/308

Definitions

S.Pingeletal.,PotentialInducedDegradationofSolarCellsandPanels,35thIEEEPVSC,Honolulu,2010,pp.28172822.

ElectroluminescenceofmcSimodulestringsindicatingshuntinginthenegativeportionofacentermounted or

floating

string

Electrochemical

corrosioncSi

Mon&Ross

JPL,1985 Polarization

cSi

Swanson

SunPower,2005

?Otherpowerloss

thin

films

unpublished

Delamination,corrosion

aSi

Wohlgemuth

BPSolar,

2000


9/309

Definitions

S.Pingeletal.,PotentialInducedDegradationofSolarCellsandPanels,35thIEEEPVSC,Honolulu,2010,pp.28172822.


floating

string

Electrochemical

corrosioncSi

Mon&Ross


cSi

Swanson

SunPower,2005

?Otherpowerloss

thin

films

unpublished


aSi

Wohlgemuth

BPSolar,

2000

Needsanunambiguousname


10/3010

Definitions thisstandardwillcover

S.Pingel

et

al.,

PotentialInducedDegradationofSolarCellsandPanels,35thIEEEPVSC,Honolulu,2010,pp.28172822.


floating

string

Electrochemical

corrosioncSi

Mon&Ross


cSi

Swanson

SunPower,2005

?Otherpowerloss

thin

films

unpublished


aSi

Wohlgemuth

BPSolar,

2000


11/3011

Definitions thisstandardwillcover

S.Pingel

et

al.,

Potential

Induced

Degradation

of

Solar

Cells

and

Panels,

35th

IEEE

PVSC,

Honolulu,

2010,

pp.

28172822.

ElectroluminescenceofmcSimodulestringsindicatingshuntinginthenegativeportionofacentermounted orfloatingstring

Polarization

cSi

Swanson

SunPower,2005


12/3012

Systemvoltagedurability

Designedto

cover

cSi

MorethanjustPIDofconventionalcells/modules

Polarization

(like

SunPower)

NonreversibleelementsofPID

Rearjunctionbifacialcells. ECNbifacial/YingliPanda

HIT

cells

Framed/unframedmodulesofvarioustypes

Longtermviewforharmonizationwiththinfilmsystemvoltagedurability


13/3013

Factorsfortest leakagecurrent

Glass(Nacontent)

Circuitresistancefactors cuttingrelevantseriesRcutsdegradation

Glassface

(H2O,conductivedirt)

Framematerials,

tapes,

and

design

Interfaces

Encapsulant

Groundingscheme

(groundedvs.ungrounded)

Voltagepotential

of

active

layer,

and

leakage

from

that

voltagetogroundgoverndegradationinsusceptiblemodules

T.J.McMahone,Prog.Photovolt:Res.Appl.2004;12:235248


14/3014

Testfactors

Voltage Mounting/grounding

Humidity,surface

conductivity Temperature

-40%

-35%

-30%

-25%

-20%

-15%

-10%

-5%

0%

5%

1 2 3 4 5 6 7 8 9

Voltage position (1=negative, 9=most positive)

%changeinpower

Power Loss vs. Position in String:Polarization, SunPower Modules

R . M. Swanson, The surface polarization effect in high-efficiency

solar cells, PVSEC-15, Shanghai


15/3015

Testfactors

Completingthecircuittogroundinamanner

representativeof

mfg.

module

mounting

scheme

Leakagecurrentmaybemeasuredasinindicatorof

modulepackageresistance


Humidity,surface



16/3016

Testfactors

Alfoil,carbonfilm,etc,forsurfaceconductivity

+Quick/cheap

+Goodscreeningtest

Wontdifferentiatehumidityeffects

(waterleachesNalimeglass)

unclearhowitconnectstotexturedglass

bypassesframe

or

laminate

mounts

ability

to

reducedegradation,limitingfixestoPID

www.bangkoksolar.com

From:C.R.Osterwald,SolarEnergyMaterials&SolarCells79(2003)2133

*Modulesthatlackaframeandusemountingpointsbondedtothebacksheetglass

shownodamage[totheextenttested].

*Damage

rates

can

be

slowed

if

leakage

currents

that

are

caused

by

voltage

potentialsbetweentheframeandtheinternalcircuitryarereduced.


Humidity,surface

conductivity Temperature Pho

to:ErikEikelboom

2011:10:1

7


17/3017

Testfactors

Module leakage vs. humidity

P.Hackeet.al.,25th EPVSEC,610September2010,Valencia,Spain

Surfaceconductivityofsodalimeglassvs.humidity

Becauseweneedtomeasurethe

performanceofnotonlythemodule

laminate,buttheframeormounts,the

standardaswrittenuseshumidityforthe

circuitto

ground.


Humidity,surface



18/3018

Testfactors

Degradation vs. time of mc-Si modules, -600 V, 85% RH

P. Hacke et al., Testing and Analysis for Lifetime Prediction of Crystalline Silicon PV ModulesUndergoing Degradation by System Voltage Stress, 38th IEEE PVSC, Austin, 2012

50C

60C

85C


Humidity,surface


RH=85%

Temperature dependence, repeatable Arrhenius behavior over temperature range, unless alternate conduction paths exist


19/3019

Testlevels

D.Buemi,ThinFilmPVPowerstheNumber1GlobalSolar

Integrator,davebuemi.com,

accessed

Feb

22,

2012

Systemvoltage,noweffectively

governedby

IEC

61730

2s

partialdischargetest,notPID,

generally

Testat

rated

system

voltage

Maximumnameplatevalue(behindthe

fence/utilitiesdontruntoULcode)

Bothpolarities(ifnotpolarityisspecified)

Slight

acceleration

since

actual

operating

V

lower


Humidity,surface



20/3020

Forcontinuousmetallicframesencasingthe

perimeterofthemodule,thegroundterminalofthe

highvoltagepowersupplyshallbeconnectedtoa

modulegroundingpointofthemodule.

If(1)thePVmoduleisprovidedorisspecifiedforuse

withmeansformountingand(2)themoduleis

designedandspecifiednottobeconnectedtoground,

thensuchmethodofmountingthemoduleshallbe

implementedto

the

extent

possible.

Testlevels


Humidity,surface


http://www.solarframeworks.comSolarFrameWorksCo,BIPVCoolPly

AccessedFeb22,2012

Draftstandard:


21/3021

Testlevels


Humidity,surface


85%RHdampheatchamber,alevelthatchambers

arecapableofholding,uniformly


22/3022

Testlevels


Humidity,surface


Whatlevelofstressinanacceleratedtestsreproduces

wellthefailuremodesweseektotestfor?

Howlong

should

it

be

stressed

at

that

temperature?

Whatistheaccelerationfactor?


23/3023

Failuremodeinfieldedmodule

Seriesresistancelosses,asseeninchambertests,arenot

yetobserved

in

the

field

ModulemountedinFlorida,USAaftertenmonthswiththeactivelayerbiasedat

1500

V

during

the

day

degraded

to

0.35

Pmax_0

EL Thermography

PL(inVoc)

Dark=recombination

PL(inJsc)

Light=seriesresistance


24/3024

Stepstressfordeterminationoffailuremode

Optical

E

L

Thermography

SiNxoxidation:notseeninfield!

PL(inVoc)

Dark=recombination

PL(inJsc)

Light=seriesresistanceMixed

mode

Seriesresistance/recombination

PIDrecombination

50C,50%RH 70C,70%RH 85C,85%RHEachstep:

1000V

stress

145

h

+1000Vrecovery145h

(145hpreconditioningatT&RHlevel


25/3025

Performanceoftwomoduletypes

InFlorida,

USA

600Vapplied

logarithmicallywith

irradiance

333days

Inchamber

85%RH

600V

Type2,85

Type2,60

Type2,50

Type1

Type2

Moredetailsat2012IEEEPVSC


26/30

26


InFlorida,

USA

600Vapplied

logarithmicallywith

irradiance

333days

Inchamber

85%RH

600V

Type2,85

Type2,60

Type2,50

Type1

Type2 ModuleType1:Acceptable

performanceinthefield

surviveswithlessthan5%

powerdropinchamber

with85%

RH,

60C,

rated

systemvoltage,for96h


27/30

27


InFlorida,

USA

600Vapplied

logarithmicallywith

irradiance

333days

Inchamber

85%RH

600V

Type2,85

Type2,60

Type2,50

Type1

Type2 ModuleType1:Acceptable

performanceinthefield

surviveswithlessthan5%

powerdropinchamber

with85%

RH,

60C,

rated

systemvoltage,for96h

ModuleType

2:

5%

powerdropin4934h

inFloridaand12h in

chamberat60 C,

(consideredafailing

module)Moredetailsat2012IEEEPVSC


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28

Testlevels

Usecondition:

Florida,

USA,

600

V

simulated

array

V

Accelerationcondition:85%RH,Tasplotted

Failure:0.95Pmax_0

AF=427at60C,85%RH

Testduration,96h

Fieldequivalent:4.7y

Thefollowingconditionsshallbeapplied:

Chamberairtemperature60C 2C

Chamber

relative

humidity

85

%

5

%

RH Testduration96h

Voltage:moduleratedsystemvoltageandpolarities

(onemoduleperpolarity)


Humidity,surface


Draftstandard:


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29

Nextsteps:Testingatmultiplelabs

Determinereproducibility

23samplespercondition

Presumably85%

RH

60C,

but

consider

alternates

forpostIEC61215tests

5labs

NREL

ASU

letusknowifyouareinterested!

Samplesfrom3manufacturers


30/30

Thankyou

NREL Considerations for a Standardized Test for PID of Cristalline Silicon PV Modules

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