An experimental approach to investigate behaviors of crack formation of PV backsheets

To address the backsheet cracking observed in field deployed photovoltaic (PV) modules, crack formation of backsheets at various tensile strain levels were studied as function of ultraviolet (UV) light exposure times. In a fragmentation test, the critical and saturation strains for cracks in PET sheets (exposed at z 25 °C) decreased with increasing exposure times (from 140 h to 480 h), and the crack patterns changed from a discontinuous pattern to a continuous (channel) pattern. In the case of a PPE backsheet UV exposed for 240 h at 85 °C, only the channel cracks were observed for the fragmentation test, and these channel cracks were not visible after removing tensile load.