Modeling, imaging and resistance analysis for crystalline silicon photovoltaic modules failure on thermal cycle test

The research investigates the thermo-mechanical fatigue, degradation and failure behaviors of crystalline silicon (c-Si) photovoltaic (PV) module in thermal cycling (TC) 200 tests using both simulation and experimental analysis. A 2D finite element (FE) model of PV module is established, to elevate the developing trend of stress concentration of factors under cyclic thermal and cold shock. The copper-solder-silver/aluminum joint accumulating the high magnitude of strain energy density exhibits the high risky breakage in the assembly, which will be the weakest link directly and induce further fatigue cracks, which in turn increases the series resistance (Rs). In actual TC200 operation, the solder joint disconnection, finger breakage, cell fracture and darkness were observed by electroluminescence (EL) images and the corresponding impact on their Rs has been investigated, to help to investigate the root cause of module failure thereby enhancing the durability of PV modules.