Failure Modes Evaluation of PV Module via Materials Degradation Approach

AbstractThe primary objective of this study is to investigate and understand how polymeric materials in photovoltaic (PV) module as a function of long term aging effect on the durability, reliability and safety of PV modules. Si-based PV modules were made with EVA encapsulant and different types of backsheet and then subjected to accelerated weathering conditions in laboratory-controlled exposure chambers. The disassembly approach of the PV modules was developed to obtain the samples. All of the aged sample materials were directly obtained from the PV modules. Specific coupons of EVA/glass based on the similar module design were fabricated and applied with the same lamination process as in the manufacturing for the interfacial adhesion tests. The study covers the measurements on the samples including EVA, coupons and the modules made with different backsheets as a function of exposure time under accelerated conditions of damp heat (85°C and 85% RH) or UV (∼ 80 W/m2) chamber. The durability of materials degradation and properties was tested every 1000 hours up to 4000 hours including: (1) thermal characterisation by TGA, DSC, (2) inter layer adhesion by peeling strength, (3) chemical degradation by FTIR, (4) acetic acid content using Pyrolysis-GC/Mass, and (5) thermo-mechanical tensile modulus by DMA. Non-intrusive measurements were also performed at every 250 hours on the modules such as I-V measurements, Fill Factor and Wet Insulation. The correlation between the materials degradation behaviour and the performance of the PV module, the impact of using different backsheets (TPT or TPE), and key failure mode(s) development related to the safety and performance of the PV module will be addressed from the study