Accelerated ageing tests of photovoltaic laminates are requested by the IEC standards for quality control, which require the assessment of the electrical power losses after a prescribed amount of temperature and/or humidity cycles inside a climatic chamber (thermal cycling, humidity freeze, and damp heat tests). Since electric damage is measured only at the end of such tests, its kinetics induced by thermo-elastic stresses and the related degradation phenomena are reported in few cases. The aim of this study is to investigate the progress of damage, reporting the results of an unprecedented experimental campaign on a photovoltaic mini-module composed of nine multi-crystalline silicon solar cells, one of them containing a cracked cell, subject to a revised thermal cycling test including moisture. Every 40 cycles, and up to 460 (corresponding to 1840 h of testing), the progress of electric damage is assessed by monitoring the evolution of the overall electric resistance of the module. Moreover, electroluminescence images are taken with the same time interval, to assess local damage phenomena responsible for electric power-losses. Cracks are found to significantly accelerate the progress of damage as compared to what happens in intact solar cells, inducing progressive gridline failure and the spread of electrically inactive zones.
Quintana M, King D, McMahon T, et al. Commonly observed degradation in field-aged photovoltaic modules. In: Proceedings of the 29th IEEE photovoltaic specialists conference, New Orleans, LA, USA, 19--24 May 2002, pp.1436–1439. Institute of Electrical and Electronics Engineers, Inc.
2.
Wohlgemuth J, Cunningham D, Nguyen A, et al. Long term reliability of PV modules. In: Proceedings of the 20th European photovoltaic solar energy conference, Barcelona, Spain, 6--10 June 2005.
3.
OsterwaldCMcMahonT. History of accelerated and qualification testing of terrestrial photovoltaic modules: a literature review. Prog Photovolt2009; 17: 11–33.
4.
MunozMAlonso-GarciaMVelaN, et al.Early degradation of silicon PV modules and guaranty conditions. Solar Energy2011; 85: 2264–2274.
5.
PaggiMBerardoneIMartireM. An electric model of cracked solar cells accounting for distributed damage caused by crack interaction. Energy Proc2016; 92: 576–584.
6.
CorradoMInfusoAPaggiM. Simulated hail impacts on flexible photovoltaic laminates: testing and modelling. Meccanica2017; 52: 1425–1439.
7.
BorriCGagliardiMPaggiM. Fatigue crack growth in silicon solar cells and hysteretic behaviour of busbars. Solar Energy Mater Solar Cells2018; 181: 21–29.
8.
Lannoy A and Procaccia H. Evaluation et maîtrise du vieillissement industriel, Éditions Tec & doc, 2005.
9.
SpertinoFCiociaADi LeoP, et al.A power and energy procedure in operating photovoltaic systems to quantify the losses according to the causes. Solar Energy2015; 118: 313–326.
10.
CharkiALarondeRBigaudD. The time-variant degradation of a photovoltaic system. J Solar Energy Eng2013; 135: 024503.
11.
VázquezMRey-StolleI. Photovoltaic module reliability model based on field degradation studies. Prog Photovolt2008; 16: 419–433.
12.
PaggiMCorradoMBerardoneI. A global/local approach for the prediction of the electric response of cracked solar cells in photovoltaic modules under the action of mechanical loads. Eng Fract Mech2016; 168: 40–57.
13.
SchwingshacklCPetittaMWagnerJE, et al.Wind effect on PV module temperature: analysis of different techniques for an accurate estimation. Energy Proc2013; 40: 77–86.
DunlopED. Lifetime performance of crystalline silicon PV modules. Photovolt Energy Convers2003; 3: 2927–2930.
16.
GagliardiMLenardaPPaggiM. A reaction-diffusion formulation to simulate EVA polymer degradation in environmental and accelerated ageing conditions. Solar Energy Mater Solar Cells2017; 164: 93–106.
17.
GagliardiMPaggiM. Long-term EVA degradation simulation: climatic zones comparison and possible revision of accelerated tests. Solar Energy2018; 159: 882–897.
18.
BerardoneILopez GarciaJPaggiM. Analysis of electroluminescence and infrared thermal images of monocrystalline silicon photovoltaic modules after 20 years of outdoor use in a solar vehicle. Solar Energy2018; 173: 478–486.
19.
Koentges M, et al. Review of failures of photovoltaic modules. International Energy Agency, Report IEA-PVPS T13-01, 2014. [ISBN 978-3-906042-16-9].
20.
IEC 61215:2016. Crystalline silicon terrestrial photovoltaic (PV) modules – design qualification and type approval. Geneva: International Electrotechnical Commission, 2016.
21.
IEC 61730:2016. Photovoltaic (PV) module safety qualification – part 2: Requirements for testing. Geneva: International Electrotechnical Commission, 2016.
22.
IEC 61215-1-3:2016. Terrestrial photovoltaic (PV) modules – design qualification and type approval – part 1-3: special requirements for testing of thin-film amorphous silicon based photovoltaic (PV) modules. Geneva: International Electrotechnical Commission, 2016.
23.
Koentgers M, Kunze I, Kajari-Schroeder S, et al. Quantifying the risk of power loss in PV modules due to micro cracks. In: 25th European photovoltaic solar energy conference, Valencia, Spain, 6--10 September 2010, pp.3745–3752.
24.
Reis AM, Coleman NT, Marshall MW, et al. Comparison of PV module performance before and after 11-years of field exposure. In: 29th IEEE photovoltaic specialists conference, New Orleans, LA, USA, 19--24 May 2002, pp.1432–1435. Institute of Electrical and Electronics Engineers, Inc.
25.
ParrettaABombaceMGraditiG, et al.Optical degradation of long-term, field-aged c-Si photovoltaic modules. Solar Energy Mater Solar Cells2005; 86: 349–364.
26.
PozzaASampleT. Crystalline silicon PV module degradation after 20 years of field exposure studied by electrical tests, electroluminescence, and lbic. Prog Photovolt2016; 24: 368–378.
27.
Sánchez-FrieraPPiliougineMPelaezJ, et al.Analysis of degradation mechanisms of crystalline silicon PV modules after 12 years of operation in southern Europe. Prog Photovolt2011; 19: 658–666.
28.
Tanahashi T, Sakamoto N, Shibata H, et al. Electrical detection of gap formation underneath finger electrodes on c-Si PV cells exposed to acetic acid vapor under hygrothermal conditions. In: 43rd photovoltaic specialists conference (PVSC), Portland, OR, USA, 5--10 June 2016 pp.1075–1079. Institute of Electrical and Electronics Engineers, Inc.
29.
KraftALabuschLEnsslenT, et al.Investigation of acetic acid corrosion impact on printed solar cell contacts. IEEE J Photovolt2015; 5: 736–743.
30.
KingDQuintanaMKratochvilJ, et al.Photovoltaic module performance and durability following long-term field exposure. AIP Conf Proc1999; 462: 565–571.
31.
AokiYOkamotoMMasudaA, et al.Early failure detection of interconnection with rapid thermal cycling in photovoltaic modules. Jpn J Appl Phys2012; 51: 10NF13.
32.
PaggiMKajari-SchrderSEitnerU. Thermomechanical deformations in photovoltaic laminates. J Strain Anal Eng Des2011; 46: 772–782.
33.
PaggiMBerardoneIInfusoA, et al.Fatigue degradation and electric recovery in silicon solar cells embedded in photovoltaic modules. Sci Rep2014; 4: 4506.
34.
Saint-Lary A, Ed-daoudi S, Delsol T, et al. Photovoltaic modules reliability on accelerated and natural test – the ELVIRE Project. In: Proceedings of 27th European photovoltaic solar energy conference and exhibition, Frankfurt, Germany, 24--28 September 2012, pp.3523–3525. EU PVSEC.
35.
Wohlgemuth JH, Cunningham DW, Nguyen AM, et al. Long term reliability of PV modules. In: Proceedings of the 20th European photovoltaic solar energy conference, Barcelona, Spain, 6--10 June 2005, pp.1942. EU PVSEC.
36.
Wohlgemuth JH and Kempe MD. Equating damp heat testing with field failures of PV modules. In: 39th IEEE photovoltaic specialists conference, Tampa, FL, USA, 16--21 June 2013, pp.126–131. Institute of Electrical and Electronics Engineers, Inc.
37.
Herrmann W and Bogdanski N. Outdoor weathering of PV modules – effects of various climates and comparison with accelerated laboratory testing. In: 37th IEEE photovoltaic specialists conference, Seattle, WA, USA, 19--24 June 2011, pp.2305–2311. Institute of Electrical and Electronics Engineers, Inc.
38.
LenardaPPaggiM. A geometrical multi-scale numerical method for coupled hygro-thermo-mechanical problems in photovoltaic laminates. Comput Mech2016; 57: 947–963.
