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Case Western Reserve University (2020)

Degradation of Photovoltaic Packaging Materials and Power Output of Photovoltaic Systems : Scaling up Materials Science with Data Science

Wang, Menghong

Titre : Degradation of Photovoltaic Packaging Materials and Power Output of Photovoltaic Systems : Scaling up Materials Science with Data Science

Auteur : Wang, Menghong

Université de soutenance : Case Western Reserve University

Grade : Doctor of Philosophy (PhD) 2020

Résumé
The global photovoltaic (PV) industry has seen a rapid increase in installed capacity in recent years. As of 2019, the cumulative installed capacity of PV reached 627 GW, and the need to decrease levelized cost of energy (LCOE) initiated the pursuit to extend the lifetime of PV modules. The degradation of polymeric PV packaging materials is a crucial factor in determining the power loss rate and lifetime of real-world PV system. Two of the PET based backsheets contain a fluoropolymer outer layer, and the other one contains a thermoplastic polyolefin (TPO) inner layer. Indoor accelerated testing on two sets of samples was used to isolate the degradation mechanism induced by humidity and UV. This testing included damp heat (DH) exposure (85 C, 85 % relative humidity) and QUV exposure (1.55 W/m2 at 340 nm, black panel temperature 70 C). In DH testing, yellowing induced by antioxidant hydrolysis and additive migration can be observed. Hydrolysis is evident in EVA, whereas POE is relatively stable in DH. Physical degradation of backsheet materials induced by damp heat, including the phase transition of polyvinylidene fluoride (PVDF) and increase of crystallinity of PET, exposed potentialities for backsheet failure. In QUV exposure, chain scission of both encapsulants were confirm by indentation on multi-layer polymeric systems, and by Fourier transform infrared (FTIR) spectroscopy. In both DH and QUV exposures, POE exhibited better stability compared to EVA. The all-PET and PET + PVDF backsheets shows comparable performance, whereas the TPO + PET + PVDF backsheet shows the worst chemical and mechanical stability. A statistical tool, Analytic Suns-Voc, was developed to connect indoor polymer degradation under accelerated testing to large-scale, outdoor power loss of PV systems. Through the different time-series power loss modes obtained with Analytic Suns-Voc, the fielded PV modules can be viewed as sensors, and the degradation status of polymeric packaging materials can be continuously monitored.

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Page publiée le 25 janvier 2023