Exploration of degradation pathways resulting in reduction in volume resistivity in photovoltaic backsheets under sand erosion and aging in desert conditions

Abstract

The manufacturers of photovoltaic (PV) modules often follow the philosophy of “one design for all climatic conditions”, which can curtail the life of the modules if the materials aren’t suitable for the extreme climates. During desert-storm like conditions, erosion of the backsheet due to desert sand particles cannot be ignored. This study explores the extent of damage as well as degradation pathway for the PV backsheets after erosion by sand particles sourced from desert A and desert B. The particles of desert A are harder and possess higher aspect ratio than the particles of desert B. For this study, polyethene terephthalate (PET) and polyvinylidene fluoride (PVDF) based backsheets are selected owing to their popularity in the PV industry. The backsheets have been subjected to sequential ageing which comprises of damp heat ageing, ultraviolet ageing and temperature cycling. These backsheets are then subjected to erosion at 30° angle with a flow velocity of 10 m/s. The PET based backsheet, are found to be more resistant to erosion than the PVDF based backsheet owing to higher hardness. The damage to the backsheets due to the sequential aging and sand erosion results in a loss of volume resistivity by an order of magnitude. Therefore, to improve the reliability of the PV installations in the deserts, it is recommended to choose the backsheet material based on the environmental and mechanical stressors predominant in the location of PV installation.