Lifetime Evaluation of Photovoltaic Polymeric Backsheets under Ultraviolet Radiation: From Chemical Properties to Mechanical Modeling.

Photovoltaic (PV) power generation plays a significant role with the increase of installed capacity of renewable energy. The effects of environmental stress on insulating backsheets have been considered as the main cause of failure in PV systems. However, traditional aging models are difficult to realize the comprehensive evaluation of the lifetime of insulating backsheets. In this paper, the analytical method of complex chemical degradation related to the insulation was replaced by a physics-based method to quantify the elongation at the break as a function of time corresponding to temperature and radiation. In contrast to traditional aging models, this model simply used one parameter, namely drop-off rate (), to reflect the degradation of polymers under various environmental stresses. The effect of ultraviolet (UV) radiation on the model was considered. Moreover, the electrical degradation, chemical changes, and mechanical properties caused by UV radiation were investigated to provide the reference for the lifetime of evaluation. The research is significant for comprehensively evaluating the lifetime of insulating materials for PV systems and other power equipment.