Reliability and long term durability of bifacial photovoltaic modules using transparent backsheet

Abstract

The reliability and long-term durability of two bifacial photovoltaic modules, a glass–transparent backsheet (GB) module and a glass–glass (GG) module, were compared. The output degradations after UV, damp heat (DH) and thermal cycle tests for GB modules were similar to those for GG modules in the case of using ethylene vinyl acetate (EVA) encapsulant. In addition, GB modules using polyolefin encapsulant exhibited much higher reliability in a further extended DH test than GG modules using EVA encapsulant. It was also shown from an outdoor exposure test that the temperature of the GB module was clearly lower than that of the GG module, leading to a higher open-circuit voltage for the GB module. GB modules, even those using EVA encapsulant, had long-term durability similar to that of GG modules in addition to the advantages of a light weight, easy fabrication, and lower module temperature in a hot ambient.