Degradation phenomena and a guiding principle for improved reliability of photovoltaic modules

Abstract

Various combined loads are given to photovoltaic modules exposed outdoors, leading to a decrease in output power. Although degradation phenomena in photovoltaic modules are very complicated, degradation factors are roughly classified into three categories; shading, less carrier collection ability, and less photovoltaic ability. In this paper various degradation phenomena will be introduced based on these three categories. Potential-induced degradation will be introduced in detail with recent findings. The influence of ultraviolet irradiation, which is an inevitable load for photovoltaic modules exposed outdoors, on degradation phenomena, will also be discussed.