IEC
IEC TS 63209-1 I®
Edition 1.0
TECHNICAL SPECIFICATION
P h o t o v o l t a i c m o d u l e s - E x t e n d e d --s s t r e s s t es es t i n g - P a r t 1: 1: M o d u l e s
tonal Eleclroiechnlc Eleclroiechnlca* a* Commission
2021-04
A
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IEC
IEC TS 63209-1 ® _______________________________________________________________ ____________________________________________________________________________ _____________
Edition 1.0
2021-04
TECHNICAL SPECIFICATION
P h o t o v o l t a i c m o d u l e s - E x t en e n d e d - s t r e s s t es es t i n g P a r t 1: 1: M o d u l e s
INTERNATIONAL ELECTROTECHNICAL COMMISSION
ICS 27.160
ISBN 978-2-8322-9728-5
Warning! Make sure that you obtained this pub lication from an authorized authorized d istributo istributo r. Copyright International Electroıectınlca Electroıectınlcaff Commission
© Registered trademark of the International Electrotechnical Commission
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IEC TS 6 3 2 0 9 -1 :2 0 2 1 © IEC 2021
CONTENTS F O R E W O RD ............... ....................... ............... .............. ............... ................ ............... .............. .............. .............. .............. ............... ................ ............... .............. ............... ................ ............... ............. ......3 3 IN TR O D U C T IO N ........ ............... ............. .............. ............... .............. ............... ................ ............... .............. ............... ............... ............... ................ ............... .............. ............... ................ ..............5 ......5 1 2 3
S co p e ............... ...................... ............... ................ ............... ............. .............. ............... .............. ............... ................ ............... .............. ............... ................ ............... ............. .............. ............... ............ ..... 6 No rmat rm ative ive re fe re n c e s ............... ....................... ............... .............. .............. .............. .............. ............... ................ ............... .............. ............... ................ ............... .............. .............6 ......6 Terms Terms,, definiti definitions ons and abbreviated te rm s ....................................................................................... 7
4
Se lec tion tio n of te st sa m pl es ........ ................ ............... .............. .............. .............. ............... ................ ............... .............. .............. .............. ............... ................ ............... ..............8 .......8
5
Ch ara cte riza tion and sta biliz atio n tec hn iqu es to be a p p lie d .... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ....... ... 8
6
5.1 5.2
G en e ra l............... l..................................................... .......................................................................... .......................................................................... .................................................. ............ 8 Ph ysi ysica call m ea su re m en t........... t.................. .............. .............. ............... ................ ............... .............. .............. .............. ............... ................ ............... .............. .............8 ......8
5.3 5.4
Vi sual su al in sp e ct io n ....... .............. ............... ................ ............... .............. .............. .............. ............... ................ ............... .............. .............. .............. ............... ................ ............ .... 8 Ini Initia tiall s ta b iliz il iz a tio ti o n ....... .............. ............... ................ ............... .............. .............. .............. ............... ................ ............... .............. ............... ................ ................ ............... ......... 8
5.5 5.6
P er fo rm a nc e ........ ................ ............... .............. ............... ................ ................ ............... .............. ............... ................ .............. .............. ............... .............. ............... ................ ..........8 ..8 Ins ula tio n t e s t ........ ............... .............. ............... ................ ............... .............. .............. .............. ............... ................ ............... .............. ............... ................ ................ ............... ....... 8
5.7 5.8
We t lea kage ka ge c u rr e n t............ t................... .............. .............. .............. ............... ................ ............... .............. ............... ................ .............. .............. ............... .............. ......... .. 9 E lec tro lu lum m ines in es ce nt im a g in g ........ ............... .............. ............... ................ .............. .............. ............... .............. ............... ................ ............... .............. .............9 ......9
5.9 5.1 0
Ins ula tio n thick th ick ne ss te s t............ t.................... ............... .............. .............. .............. ............... ................ ............... .............. .............. .............. ............... ................ .......... 9 Th erm al cy cl in g ........ ............... .............. ............... ................ ................ ............... .............. ............... ................ ................ ............... .............. ............... ................ ............... ...........9 ....9
5.11 5.12 5.1 2
Hu mi dit dity y fr e e z e ........ ................ ................ ............... .............. ............... ................ ............... .............. .............. .............. ............... ................ ............... .............. .............. .............9 ......9 Fina Finall st ab ili z a tio n ............... ...................... .............. .............. ............... ................ ............... .............. .............. .............. ............... ................ ............... .............. .............. ........... .... 9
Data co llect lle ction ion and stres str es s a p p lic a tio n ....... .............. .............. .............. ............... ................ ............... .............. .............. .............. ............... ................ ...............9 .......9 6.1
G en e ra l............... l..................................................... .......................................................................... .......................................................................... .................................................. ............ 9
6.2
Ini Initia tiall ch ar ac te riz a tio n ....... .............. ............... ................ ............... .............. .............. .............. ............... ................ ............... .............. ............... ................ .............. .........9 ...9
6.3
Te st se quen qu ence ce
6.4 6.5
Te st se qu ence en ce 2: M echa ec hanic nic al s tr e s s ............... ...................... ............... ................ ................ ............... .............. ............... ................ ............... .......10 10 Test sequence 3: Sequential testing including UV stress tomo tomo dule b a c k .... ........ ........ ........ .......1 ...11 1
6.6 6.7
Te st se quen qu ence ce Test sequence
1: Th erm al fa ti g u e ........ .............. .............. ............... .............. ............... ................ ............... .............. .............. .............. ............... ........10 10
4: Dam p h e a t.............. t..................... .............. .............. .............. ............... ................ ............... .............. ............... ................ .............. ........ .. 12 5: Potential-Induced Degradation (PID) (PID)testing......................................12 testing......................................12
7
R e p o rt ........ ............... .............. ............... ................ ............... .............. .............. .............. ............... ................ ............... .............. .............. .............. ............... ................ ............... .............. .............. ......... .. 13
8
Te st flo w and p ro c e d u re s ....... .............. .............. .............. ............... ................ ............... .............. .............. .............. ............... ................ ............... .............. .............. ............ ..... 14
An nex ne x A (in fo form rm at ativ ive) e) Ap prop pr op ria te use o f IEC TS 632 63209-1 09-1 - Po ten tia l we akne ak ne sses ss es of the inc lud ed te st se qu en ce s.................... s........................... .............. ............... ................ ................ ............... .............. ............... ................ ................ ............... .............. .............. ....... 15 A.1
G en er al ....... .............. ............... ................ ............... .............. .............. .............. ............... ................ ............... .............. ............... ................ ................ ............... .............. ............... ........... ... 15
A.2 A .2
Fals e ne ga tiv es /fa lse p o s it iv e s ....... .............. .............. .............. ............... ................ ............... .............. ............... ................ .............. .............. ..............15 ......15
A.3 A .3 A. A.4 4
A pp ro roxim xim at ion s to se rvice rv ice l i f e .. .......... ................ .............. .............. ............... .............. ............... ................ ............... .............. .............. .............. ............. ...... 16 De Desig sign n to te s t............ t.................... ............... .............. .............. .............. ............... ................ ............... .............. .............. .............. ............... ................ ............... .............. ........... .... 16
An nex ne x B (in fo rm at ativ ive) e)Ba Ba ckg rou nd on IEC TS 63 63209209- 1 ............... ...................... .............. .............. ............... ................ ............... .............. ........... .... 17 B.1
G en e ra l............... l..................................................... .......................................................................... .......................................................................... ................................................ .......... 17
B.2
Seque nce 1 1:: Therm al fatigue - Thermal cycling 600 cycles = 3x IEC 61215 (sim ilar to oth er exte nde d stres s pr ot oc ol s) .... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ .......17 ...17 Seque nce 2: Mec hanical stress (adds static load to tosequence sequence similar to other extended stress protocols)..........................................................................................17
B.3 B.4 B.5
Sequence 3: Combines U UV, V, moisture and tempe rature/mech anical cycling to stre ss poly m eric er ic co m p on e nt s............. s.................... ............... ................ ............... .............. .............. .............. ............... ................ ............... .............. ......... .. 17 Seque nce 4: Damp heat moistu re expos ure - DH 2 000h 000 h = 2x IEC 61215 (sim ilar to oth er exte nde d stres s pr ot oc ol s) .... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ .......18 ...18
B.6 Sequence 5: Potential-Induced Degradation Degradation(PID) (PID) testing................................................18 B ib lio gr ap hy ....... .............. ............... ................ .............. .............. ............... .............. ............... ................ ............... .............. .............. .............. ............... ................ ............... .............. .............. .............. ....... 19
Figure 1 - Full test fflow low - Eac Each h box rrefers efers tto o the the corresponding MQT in IIEC EC 6121 5-2 ............ 14 Copyright International Electroiectmlcaf Commission
IEC TS 632 09 -1:2021 -1:2021 © IEC 2021 2021
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INTERNATIONAL ELECTROTECHNICAL COMMISSION
P H O T O V O L T A I C M O D U L E S - E X T E N D E D - S T R E S S T E S T IN IN G Part 1: Modules
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IEC TS 63209-1 has been prepared by IEC technical committee 82: Solar photovoltaic energy systems. It is a Technical Specification. The text of this Technical Specification is based on the following documents: DTS
R e p o rt o n v o tin g
8 2 /1 8 2 0 /D T S
8 2 /1 8 7 3 / R V D T S
Full information on the voting for its approval can be found in the report on voting indicated in the above table. modules es A list o f all pa parts rts in t he IEC 63 6320 209 9 se serie rie s, pu bli blish shed ed un de r th e ge ne ral ra l tit title le Photovo ltaic modul - Extended-s Extended-stress tress test testing, ing, can be found on the IEC website.
The language used for the development of this Technical Specification is English. Copyright International Electroiectmlcaf Commission
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IEC TS 63209-1:2021 © IEC 2021
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in accordan ce wit with h ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplem ent, available at www.iec.ch/members_experts/refdocs . The main document types developed by IEC are described in greater detail at www.iec.ch/standardsdev/publications . The committee has decided that the contents of this document will remain unchanged until the stability date indicated on the IEC website under " http://webstore.iec.ch http://webstore.iec.ch"" in the data related to the specific document. At this date, the document will be • •
reconfirmed, withdrawn,
•
replaced by a revised edition, or
•
amended.
Copyright International Electroiectinlcai Commission
IEC TS 63209-1:2021 © IEC 2021
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INTRODUCTION Existing qualification test standards such as IEC 61215 standard series have been very useful for identifying module designs that avoid most early field failures, but are not intended or able to demonstrate long term performance in all locations within the scope of those documents. In order to assess the risk of product failure it has become industry practice for the different stakeholders to require results of test protocols beyond baseline type approval and safety tests according to the IEC 61215 standard series and IEC 61730 standard series. These extended stress test protocols primarily contain aforementioned baseline tests in different sequences and/or increased test duration or number of cycles. They originate from the various experiences made by third parties such as test institutes/ independent engineering firms/ owners engineers and aim to cause aging that would be seen after long term use of PV modules, or apply a “test to failure” approach, aimed to identify weaknesses rather than to replicate field performance. They do not provide detailed reliability or durability predictions/estimates, but have been useful to reveal deficiencies. With many variants of extended stress test protocols in use, a standardized approach is desired. The included set of extended stress test sequences is intended to standardize the various approaches used by different industry participants, with a benefit of a common data set for reliability reviews, and a practical benefit to module manufacturers who are faced with the challenge of running (and maintaining after product changes) a number of very similar test protocols in parallel.
This global all reference comparative utilizes denominator considering the sequences of the document variants, and adds ato common this subset sequences approach that are uniquely positioned to capture special failure modes, while excluding sequences where test conditions and durations do not show results that are useful for assessing module field performance. This document is intended to align extended test protocols, in order to make results from different institutes more directly comparable and to reduce test costs and time lines for the industry. This document is intended to provide a set of data to be used for qualitative reliability risk analysis, highlighting potential failure modes and areas possibly in need of improvement. It is only useful for rank ordering modules and materials for special cases, for very large differences in performance, or with respect to specific understood failure modes and mechanisms. A robust module level rank ordering or service life prediction is beyond the scope of this document. A series of component test suites is in development to complement the module level testing in this specification.
Copyright International Electroiectmlcaf Commission
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IEC TS 632 09-1 :2021 :2021 © IEC 20 2021 21
P H O T O V O L T A I C M O D U L E S - E X T E N D E D - S T R E S S T E S T IN IN G - P a r t 1: M o d u l e s
1
Sc op e
This document is intended to provide information to supplement the baseline testing defined in IEC 61215, which is a qua lification lification test with pa ss-fail criteria. This d ocume nt provides a standardized method for evaluating longer term reliability of photovoltaic (PV) modules and for different bills of materials (BOMs) that may be used when manufacturing those modules. The included test sequences in this specification are intended to provide information for comparative qualitative analysis using stresses relevant to application exposures to target known failure modes. A sign si gn ifica ifi ca n t co ns tra in intt imp os osed ed was wa s th that at the te st du ratio ra tio n wa s lim ite ited, d, reco re co gn izing izi ng tha t customers of the test will proceed with decisions before the test results are available, if the test takes too long. With this business-relevant limitation, some known failure modes cannot be accurately addressed, most notably those related to long-term ultra-violet light (UV) exposures. While failure modes related to UV stress are known to occur on both front and back side of PV modules, the testing time required to achieve a dose of UV stress stress that causes chan ges observed in the field during the module’s intended lifetime without overstressing is beyond the scope of this document. The included backside UV stress sequence gives increased confidence for some backsheets with regard to backside cracking, and a frontside UV stress sequence is not included at all, leaving gaps for failure modes, such as encapsulant discoloration, frontside backsheet cracking, frontside delamination, etc. Other limitations of extended stress testing are described in Annex A. This document identifies vulnerabilities without attempting to gather the information needed to make a service-life prediction, which would require identifying failure mechanisms and their dependencies on all of the stresses. Annex B contains a brief background of the origins of the tests. Out of scope for this document is its use as a pass-fail criterion. The same module deployed in two different locations may fail/degrade in different ways, so a single test protocol cannot be expected to simultaneously exactly match both results, and will depend upon where and how the product deployed. Additionally, falseof positives false negatives may due to the highlyisaccelerated and extendedboth nature some of and the stress exposures, theoccur: tests may cause some changes that do not occur in the field for some module designs, and degradation which is difficult to accelerate will be missed. This document was developed with primary consideration for c-Si modules, as reflected in the targeted failure modes. However, the applied stresses are based on the service environment, and as such are relevant to generalized PV modules. Interpretation of the data resulting from these tests should always include the possibility that a design change may cause a new failure to occur. In particular, modules with different form factors (e.g. made without the standard glass frontsheet) may be found to differ in the way they fail. In every case, the data collected in this extended-stress test procedure is used as input to an analysis that may then identify the need for additional testing, to more fully assess module performance relative to the intended deploymen t conditions. conditions. 2
Normative references
The following docum ents are referred to in tthe he text in such a way that some or all of their their co ntent constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any C o p y r ig h t I n j e t r ta t o n a i E l e c i r o M j ^ p p ^ S t S ) a p p l i e s .
IEC TS 63209-1:2021 © IEC 2021
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IEC TS 60904-1-2,
Photovoltaic devices - Part characteristics of bifacial photovoltaic (PV) devices
1-2:
Measurement
of
current-voltage
ltaic c devices - Part 13: Electroluminescence of pho tovoltaic modules IEC TS 60904-13, Photovo ltai
IEC 61215-1, Terrestrial photovoltaic (PV) modules - Design qualification and type approval Part 1: Test requirements
Terrestrial pho tovoltaic modules - Design qualifi qualification cation and (PV) type IEC IEC 61215-1-1:2021, approv al - Part 1-1 1-1:: Special requiremen requiremen ts for(PV) testing of crystalline sili silicon con ph otovoltaic modules modules - Design qualification qualification and type approval IEC 61215-1-2, Terrestrial photov oltaic (PV) modules - Part 1-2: 1-2: Special requirements for ttesting esting of thi thin-film n-film Cadmium T elluride elluride (CdTe) based photovoltaic (PV) modules
IEC 61215-1-3, Terrestrial photov oltaic (PV) modules - Design qualifi qualification cation and type approval - Part 1-3: Special requirements for testing of thin-film amorphous silicon based photovoltaic (PV) modules
IEC 61215-1-4, Terrestrial photov oltaic (PV) modules modules - Design qualification qualification and type approval - Part 1-4: 1-4: Special requirements for testing testing o f thin-fil thin-film m C u(ln,GA)(S ,Se)2 based photovoltaic (PV) modules
IEC 61215-2:2021, Terrestrial photov oltaic (PV) modules approval - Part 2: Test procedures
Design qualifi qualification cation an d type type
IEC 61730 (all parts): Photovoltaic (PV) mod ule safety qualification qualification IEC 61730-2, Photovoltaic (PV) module safety qualification qualification - Part 2: Requirements for testing testing Terms, definitions definitions and symbols IEC TS 61836, Solar pho tovoltaic energy systems - Terms,
IEC TS 62782, Photovoltaic (PV) modules - Cyclic (dynamic) mechan ical load test testing ing
3
Terms, definitio ns a an nd abbreviated terms
For the purposes o f this document, the terms and definitions in IEC TS 61836 app ly, as well as the following. ISO and IEC maintain term inolog ical datab ases for use in standard ization at the following addresses: •
IEC Electropedia: availab le at http://www.electropedia.org/
•
ISO Online browsing platform: available at http://www.iso.org/obp
3.1 Module Quality Te es st MQ T
Module Quality Test in accordance with IEC 61215-2 3.2 Module Safety Test MS T
Module Safety Test in accordance with IEC 61730-2 Copyright International Electroiectmlcaf Commission
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IEC TS 6 3 2 0 9 -1 :2 0 2 1 © IEC 2021
Sele ec ction of test samples
This document describes data collection methodology. Sample selection, number of samples, and or sample sets are left to the user, based on the purpose of the data collection. The number of samples used in each test may vary between the test sequences and may be selected to emphasize the stresses anticipated in the current application. The confidence in the test results will be greater for a larger number of test samples, and inclusion of multiple samples is encouraged. 5 5.1
Characterization and stabilization techn iques to be applied General
The characterization methods are as described in published standards, such as the IEC 61215 standard series, including the technology-specific portions of these. Baseline characterization shall be completed before application of stress, and repeated after subsequent applications of stress to establish the trend of response to that stress. Additional intermediate tests may be included between application of stresses at the customer’s request. For example, additional characterization may be beneficial after mechanical stress is applied. 5 .2 .2
Physical measu remen t
Physical module measurements shall include weight, length, width, and thickness (depth) of frame. Additionally, the cell dimensions shall be recorded. Photographs of module and example cells shall be recorded. 5 .3 .3
Visual insp ection
Obse rvations are comp leted as defined in IEC 61215-2, MQT 01. All obse rvations shall be recorded and reported as part of the final report. Photographs shall be used to document any changes and included in the final report. For the visual inspection of the backsheet after UV exposure, magnification of 10X or greater is recommended using an illumination of at least that specified in IEC 61215-2, MQT 01. 5 .4 .4
Initial stabili zation
Initial stabilization shall be completed as defined in IEC 61215-2, MQT 19.1. All measurements (as defined in 5.5) shall be recorded after each stabilization step. These data shall be included in the final report. 5.5
Performance
The performance at Standard Test Conditions shall be measured as defined in IEC 61215-2, MQT 06.1. The performance at low-irradiance conditions shall be measured as defined in IEC 61215-2 MQT 07. If the test lab does not have the capability to accurately measure at low irradiance, the low irradiance measurement may be omitted. In both cases, the measurements shall be recorded including Voc, /sc> Vmp and /mp in addition to the maximum power. Performance of bifacial modules shall be characterized using IEC TS 60904-1-2 with Standard Test Conditions applied to both the front side and the back side for initial and final characterizations. Additionally (and for intermediate measurements), bifacial modules shall be charac terized u nder bifacial na mep late irradiance (BNPI) as defined in IEC 61215-1. A ll measurements shall be included in the final report. 5 .6 .6
Insulatio n test
The insulation shall be tested as defined in IEC 61215-2, MQT 03. The insulation resistance measurement shall be recorded and reported as part of the final report. Copyright I nternationa nternationall Electrot Electrotechnical echnical Commiss ion
IEC TS 6 3 2 0 9 -1 :2 0 2 1 © IEC 2021 5 .7 .7
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Wet leakage curr ent
The wet leakage current shall be measured as defined in IEC 61215-2, MQT 15. The measured leakage current shall be recorded and reported in the final report. 5 .8 .8
Electrolum inescent imaging
Electroluminescent imaging shall be completed as defined in IEC TS 60904-13, using both low and high injection levels for the initial characterization for all tests. For the post-stress characterization, the low-injection imaging is optional for test sequences 1-4. The low-injection image is required after the PID stress in test sequence 5. All high-injection images and conditions used for their measurement shall be included in the final report. Low-injection images shall be included in the final report for the PID test sequence 5, but may be omitted for the final report for the other test sequences if they are indistinguishable from the high-injection images. 5 .9 .9
Insulation thick ness test
For modules being stressed according to sequence 3, the final insulation thickness shall be measured on any polymeric insulation sheets using the procedure described in IEC 61730-2, MST 04. The measured thicknesses shall be reported. No pass-fail criteria are applied. 5 .1 .1 0
Therm al cycli ng
Thermal cycling shall be performed according to IEC 61215-2, MQT 11 with applied current defined in the technology specific subclauses of IEC 61215-1-x. For bifacial modules, current applied during MQT 11 shall be that defined in IEC 61215-1-1:2021: the peak power current at bifacial stress irradiance (BSI). 5.11 5.11
Hum idi t y f reez e
Humidity freeze shall be performed according to IEC 61215-2, MQT 12 with any technology specific modifications made consistent with IEC 61215-1-x. 5. 12 12
Final s t ab ili z at io n
Final stabilization shall be applied according to MQT 19.2 in IEC 61215-1 and the technologyspecific parts of the IEC 61215 series. In sequence 4 (damp heat) of this document, each final stabilization shall include the stress-specific stabilization for B-0 LID, as specified in MQT 19.3 of IEC 61215-2:2021. 6 6.1
Da t a c o l l e c t i o n a an nd stress application General
The individual stress application methods (without pass-fail criteria) are as described in IEC 61215 series and IEC 61730 series, including the technology-specific parts of these. This document describes which characterization tools to apply after each interval of stress application. The sequences are summarized in Clause 8. 6 .2 .2
Initia all c h a r a c t e r i z a t i o n
Physical measurements shall be recorded as described in 5.2 to identify variations from sample to sample and to precisely define the properties of the test samples for further comparison. In the final report, these measurements shall be reported and compared with any corresponding values found on the product specifications sheet. All mo du les sh shal alll be ch ar ac te teriz riz ed be for e ap pl plica ica tio n o f stres str es s using usi ng the me tho ds de sc rib ed in 5.2 to 5.8. Copyright International Electroiectmlcaf Commission
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IEC TS 6 3 2 0 9 -1 :2 0 2 1 © IEC 2021
Modules are subjected to five types of test sequences. 6 .3 .3
T e s t s e q u e n c e 1: T h e r m a l f a t i g u e
Test sequence 1 is intended intended to test for for thermal thermal fatigue-related failures, such as solder b bond ond failure. It follows sequence D of IEC 61215-1 and is then extended to repeat the sequence two additional times, with characterization at intermediate steps. Initially, the modules shall be characterized as described in 6.2. The stresses and characterizations are completed according to: -
Str Stress ess:: •
-
IEC 61215-2 MQT 1 11 1 Therma l cycling (200 (200 cycles, 5.10) 5.10)
Post-s Post-stress tress characteriz characterization: ation: •
IEC 61215 -2 MQT 01 Visual inspection inspection (5.3)
•
IEC 61215-2 MQT 19.2 19.2 Final stabilization (5.12)
•
IEC 61215-2 MQT 06 06.1 .1 Performa nce at STC and MQT 07 Performance at low iirradiance rradiance (5.5)
•
IEC 61215 -2 MQT 03 Insulation test (5.6)
•
IEC 61215 -2 MQT 15 Wet leakage current test (5.7)
•
Electrolum inesce nt imaging according to IEC TS 60904 -13 (5.8).
The stress and post-stress characterization shall be completed three times. A total of 600 thermal cycles shall be applied. All da data ta sh shall all be repo re po rte d. No pa ss ss-fa -fa il cr crite ite ria sh shall all be ap appli plied ed . 6 .4 .4
T e s t s e q u e n c e 2: M e c h a n i c a l s t r e s s
Test sequence 2 applies mechanical stress in a sequence intended to uncover or reduce concern about reliability problems stemming from cell cracking. For modules designed to be mounted directly on another surface, it may be difficult to define how to do the mechanical load test sequence. In this case, an assessment should be made about whether such a test would provide useful information, and, if not, the test would be omitted. The sequence includes (after 6.2 initial characterization): -
-
Stress Stress:: •
IEC 61215-2 MQT 16 Static mechanical load test. For the purpose of this this stress sequence, 2 400 Pa will be be used regardless o f tthe he design load specified for the module.
•
IE IEC C TS 62782 Cyclic Cyclic (dynamic) mechanical load load 1 000 cycles cycles of 1 000 Pa pressure pressure at room temperature
•
IEC 61215-2 MQT 1 11 1 Thermal cycling (50 cycles, 5.10)
•
IEC 61215-2 MQT 12 Hum idity freeze (10 cycles, 5.11). 5.11).
Post-stress Post-stress characterizati characterization: on: As for fo r test te st se qu quen en ce 1 in 6.3. •
All data data shall be reported. No pass-fail criteria shall b be e applied.
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IEC TS 6 3 2 0 9 -1 :2 0 2 1 © IEC 2021 6 .5 .5
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T e s t s e q u e n c e 3: S e q u e n t i a l t e s t i n g i n c l u d i n g U V s t r e s s t o m o d u l e b a c k
This sequence is intended to evaluate degradation of polymeric backsheets, but it is also important to conside r degradation o f all polymeric m aterials - a ttest est that is designed to duplicate backsheet field results may also identify degradation of other module materials. The samples chosen for the test may be modules from the production line or mini modules. It is recognized by the community that the time required for a high-confidence UV-stress test is longer than the time today’s business models typically allow, so the defined test is a compromise. If a mini module is used, its construction shall be designed to be as similar as possible to the design of the full-size module. As an example, for conventional silicon modules, the mini module will include: -
Use of the same bi billll of materials (different glass is is allowed allowed - if a differen t glass is used, iitt is specified in the report).
-
Us Use e of the same lamination lamination conditions. conditions.
-
Use of same spacing between cells and between thecells thecells and the
-
Use of same cell-interconne cell-interconne ction geometries.
-
Use of ssame ame junction box and other metal-interconnect (bus wires, etc.) geometri geometries. es.
-
Inclusion of at lleast east ttwo wo rows of cells and and at least least two two cells per rrow. ow.
-
Length and width both > 20 cm.
edge of the module.
In every case, the goal is to design a mini module that will be as similar as possible to the full-size modules with special attention to the stresses that may occur for the backsheet and other polymeric materials. UV degrad ation is usua lly syne rgistic with other environm ental stressors, requiring inclusion of othe r stresses. So, test sequence 3 comb ines m ultiple tests tests from IEC 61215-2 to test for weathering-related failures (those caused by a combination of UV, moisture, heat, and thermal cycling or other mechanical stress.) Initially, the modules shall be characterized as described in 6.2. Then, the following shall be applied to the back of the module: -
Str Stress ess:: •
IEC 612 15-2 MQT 13 Damp heat (200 h only)
•
IEC 61215-2 MQT 10 UV exposure to back side as described in IEC IEC 61730 -2 MST 54 54 with increased dose of 60 kWh/m2. The UV irradiance shall be controlled within the range of 130 W/m2 and 200 W/m2 and the average value and range reported as part of the final report.
•
IEC 612 15-2 MQT 11 11 Therma l cycling (50 cycles, 5.10) plus IEC 612 15-2 MQT 12 Humidity freeze (10 cycles, 5.11)
•
IEC 61215-2 MQ T 10 UV exposure tto o back side as described in IEC 61730 -2 MST 54 54 with increased dose of 60 kWh/m2. The UV irradiance sh all be controlled within the range of 130 W/m2 and 200 W/m2 and the average value and range reported as part of the final report.
•
IEC 612 15-2 MQT 11 11 The rma l cycling (50 cycles, 5.10) plus IEC 612 15-2 M QT 12 Humidity freeze (10 cycles, 5.11)
•
IEC 61215-2 MQ T 10 UV exposure to back side as described in IEC 61730 -2 MST 54 54 with increased dose of 60 kWh/m2. The UV irradiance shall be controlled within the range of 130 W/m2 and 200 W/m2 and the average value and range reported as part of the final report.
•
IEC 612 15-2 MQT 11 The rma l cycling (50 cycles, 5.10 ) plus IIEC EC 612 15-2 MQT 12 Humidity freeze (10 cycles, 5.11)
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IEC TS 6 3 2 0 9 -1 :2 0 2 1 © IEC 2021
IEC 61215-2 MQT 10 UV exposure to back side as described in IE IEC C 61730 -2 MST 54 with short dose of 6,5 kWh/m2. The UV irradiance shall be controlled within the range of 130 W/m2 and 200 W/m2 and the average value and range reported as part of the final report.
Post-st Post-stress ress characterizati characterization: on: •
IEC 61215-2 MQT 01 01 Visual iinspe nspe ction (5.3) is comp leted after each stress stress step, with the addition of the inspection using magnification, as described in 5.3.
•
As an an option, the the visual visual inspection (5.3) may be be omitted omitted after the first set of stress app lications. In this case, case, the first two two 60 kWh/m2 UV exposures may be combined into into a single 120 kWh/m2 UV exposure and similarly, the thermal cycling and humidity freeze exposures may be combined to 100 cycles and 20 cycles, respectively.
•
Othe r chara cterization may be comp leted at custom er request, request, espe cially if visual change is noted. Power measurement and electroluminescence are omitted, as they are unlikely to correlate with field performance of the backsheet.
The following characterization is completed at the end of the entire sequence (in addition to the final visual inspection) -
IEC 61215-2 MQT 03 Insulation test (5.6).
-
IEC 61215-2 MQT 15 Wet leakage current test (5.7). (5.7).
-
IEC 61730-2 MST 04 Insulation thickness (5.9). (5.9).
All Al l da data ta sh shall all be repo re po rte d. No pa ss ss-fa -fa il cri te teria ria sh shall all be ap appl plied ied . 6. 6
Tes t s eq uen c e 4: Damp heat
Test sequence 4 applies damp heat stress to uncover problems with the packaging and/or to identify corrosion. The sequence includes (after initial characterization in 6.2). -
Stress Stress:: •
-
IEC 61215-2 MQT 13 13 Damp heat test 1 000 h
Post-s Post-stress tress characteriz characterization: ation: As fo r test te st se sequ qu en ce 1 in 6.3.
The stress and post-stress characterization shall be completed a second time. All da data ta sh shall all be repo re po rte d. No p as ss-fa failil cr crite ite ria sh shall all be ap plied pli ed . Some modules can show transients related to metastable defects. The relevant procedures in IEC 61215-2 should be followed and for interpretation of the data it should be kept in mind that new cell types may show metastabilities that differ from historical behaviour. For example, some modules may change in performance during the time between the two damp heat exposures if not kept in the dark at room temperature. 6 .7 .7
T e s t s e q u e n c e 5: P o t e n t i a l - I n d u c e d D e g r a d a t i o n ( P IID D) testing
Test sequence 5 applies damp heat stress with voltage bias to uncover problems with degradation associated when the module is placed in a system and operated at a voltage that is quite different from ground, causing small leakage currents within the module. The sequence includes (after initial characterization in 6.2):
Copyright International Electroiectmlcaf Commission
IEC TS 6 3 2 0 9 -1 :2 0 2 1 © IEC 2021 -
Stress Stress:: •
-
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IEC 61215-2 MQT 21 21 85 °C / 85 % relative hum idity applying the rated rated maximum system system voltage in whatever bias polarities are allowed by the manufacturer’s documentation. The stress shall be applied for twice the time requested for MQT 21, which would currently result in 192 h. Details of the stress application and follow up characterization and stabilization procedures designed to increase the value of this test, including any technology-specific procedures, will follow the IEC 61215-series definition of MQT 21.
Post-s Post-stress tress characteriz characterization: ation: As for fo r te st se sequ qu en ce 1 in 6.3.
All da data ta sh shall all be rep or orte ted. d. No pa ss ss-fa -fa il cr crite ite ria sh shall all be ap appli plied ed . 7
Report
The results shall be reported, normally in a test report, and shall include all the information requested by the client and necessary for the interpretation of the test and all information required by the method used. Each test report shall include at least the following information: a) a title; b) name and address of the test labo labo ratory and location where the tests were carri carried ed out; c) unique ide ntification of the report and of each page; page; d) name and and address of client, where appropriate; e) description and identification of the iitems tems tested; tested; f)
chara cterization and condition of the test items;
g) date of receipt of test items and and date(s) of test, where approp riate; h) identification of test methods used; i)
reference to sampling procedu re, and definition of bil billl of mate rials if there is n no o iss issue ue of confidentiality; or definition of bill of materials in a way that respects confidentiality, but would allow future comparisons;
j)
if the th e test te st ite items ms va varie ried d in an anyy wa y (such (su ch as use of a m inim in im od ule) ul e) de scrib sc rib e the di ffe renc re nc es between the test items, including the glass type and the module dimensions and construction differences;
k) any deviations from, ad ditions to or exclusions from from the test method, and any other information relevant to specific tests, such as environmental conditions or test methods or procedures and relevant logs, especially if chamber conditions are deviated from planned; I)
mea suremen ts, exam inations and derived results supported by tables, graphs, sketches an and d photographs as appropriate, including results of all pre-stress and post-stress characterization;
m) a stateme nt of the estimated u ncertainties o f the test results (where (where relevan t); n) a signature and tit title, le, or equ ivalent identification o f the person(s) accepting re spon sibility for the content of the report, and the date of issue; o) where relevan t, a statem statem ent to tthe he effect that the results relate only to to the items ttested; ested; p) where relevant, a statem ent to note any obse rvations that would have been deemed a failure failure by IEC 61730. Specifically, such notes would include when application of the stress normally applied in IEC 61730 caused degradation that would not have passed IEC 61730. While this test is not a pass-fail test, it is useful to understand when the result would have been a failure under regular safety testing; q) a statem statem ent that the report shall not be rreprodu eprodu ced e xcept in full, without the written approval of the laboratory. A co copy py o f this th is repo re po rt sh shall all be ke kept pt by th the e m an uf ac tu ture re r fo forr refe re fere renc nc e pu purp rpos oses es.. Copyright Internationa) Electroiectmlcaf Commission
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IEC TS 6 3 2 0 9 -1 :2 0 2 1 © IEC 2021
Te es st flow and procedu res
The full test flow is given in Figure 1.
5.2 Physical measurement
5.3 Visual inspection inspection - IEC 61215 MQT 01 5.4 Initial Initial stabili stabilization zation - IEC 61215 M QT 19.1 5.5 Performance at STC and low irradiance - IEC 61215 MQ T 06 06.1 .1 and 07 5.6 Insulation Insulation test - IEC 61215 MQ T 03 5.7 Wet leakage current current test - IEC 61215 MQT 15
I 5.8 EL imaging imaging - IEC TS 60904-13 (Isc, 0,1 x Isc)
6.3 Sequence 1
6.4 Sequence 2
--------- 1----------------6.6 Sequence 4
6.5 Sequence 3
--------- 1
6.7 Sequence 5
I Thermal cycling (200 cycles) MQT 11 1 119.2 6.1/713 6.1/713 1151EL
Static load MQT 16
1 with 10X magnification
1 19 19.2 .2 6.1/7 6.1/7 3 15 EL
Thermal cycli cycling ng (200 cycles) MQT 11
Cyclic load 1 000 x at 1 000 Pa Pa IEC TS 62782
1 19.2 19.2 6.1/7 6.1/7 3 15 EL
1 19.2 6.1/7 3 15 EL
Thermal cycli cycling ng (200 cycles) MQT 11
Thermal cycli cycling ng (50 cycles) MQT 11
119.2 19.2 6.1/7 3 |is | EL EL
Damp heat (200 h) MQT 13
.1 /7 /7 3 15 EL 1 19.2 6 .1
Humidity freeze (10 cycles) MQT 12
Repeat 3 times
Damp heat (1 000 h) MQT 13
PID (+ and/or -) (192 h) MQT 21
1 119 19.2 .2 |6.1/7|3|15| EL
1 19 2 6 .1 /7 3 15 EL
Damp heat (1 000 h) MQT 13
UV on backside (60 kWh/m2, 60° C ±5 °C) MQT 10
19 9.2 .2 6 .1 .1 /7 /7
15 EL
1 with 10X magnification
1 Thermal cycling (50 cycles) MQ T 11 Hum idity freeze freeze (10 cycles) MQT 12 1 with 10X magnification
.1 /7 /7 3 15 EL 1 19.2 6 .1
----------H-----------UV on backside (6.5 kWh/m2, 60° C ±5 °C) MQT 10
1 with 10X mag. mag.
3
15
Insul. thick. MST 04 IEC
N OT E
P ID bi as is is sel ected to match data sheet val ue(s), but stati c lload oad i s 2 400 P a regardl ess o f desi gn l oad.
Figure 1 - Full test test fl flow ow - Each Each box refers to tthe he co rrespo nding MQT MQT in in IE IEC C 61215 61215-2 -2
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(informative) A p p r o p r i a t e u s e o f IE C T S 6 3 2 0 9 - 1 - P o t en en t i a l w e a k n e s s e s o f t h e i n c l u d e d t e s t s e q u e n c e s A. 1
Ge n er al
PV module qualification tests are not intended to establish long-term reliability. There is a gap in the industry as to how to appropriately and consistently evaluate anticipated module long term performance for various applications. This is not an easy task, and impossible to be 100 % accurate at a reasonable time and cost. It is anticipated that this is an evolutionary process, and that test procedures will improve and adjust as new module designs are used, and field experiences are evaluated. The stress tests laid out in this document are a starting point, intended to provide a standardized method for extended reliability testing of PV modules allowing comparison of designs, and supporting a long-term risk analysis. The tests are best used to find weaknesses in a design, so that one can focus work in those areas as may or may not be needed. Inherent to any accelerated stress test is the risk of drawing erroneous conclusions. It is commonly understood that designing a test sequence with acceleration factors greater than about 6x to 10* will lead to highly speculative results; the combination of a target of service life of >25 years and target test duration of
