Degradation analysis of thin film photovoltaic modules

摘要

Five thin film photovoltaic modules were deployed outdoors under open circuit conditions after a thorough indoor evaluation. Two technology types were investigated: amorphous silicon (a-Si:H) and copper indium gallium diselenide (CIGS). Two 14W a-Si:H modules, labelled Si-1 and Si-2, were investigated. Both exhibited degradation, initially due to the well-known light-induced degradation described by Staebler and Wronski [Applied Physics Letters 31 (4) (1977) 292], and thereafter due to other degradation modes such as cell degradation. The various degradation modes contributing to the degradation of the a-Si:H modules will be discussed. The initial maximum power output (P-MAX) of Si-1 was 9.92 W, with the initial light-induced degradation for Si-1 similar to 30% and a total degradation of similar to 42%. For Si-2 the initial P-MAX was 7.93W, with initial light-induced degradation of similar to 10% and a total degradation of similar to 17%. Three CIGS modules were investigated: two 20W modules labelled CIGS-1 and CIGS-2, and a 40W module labelled CIGS-3. CIGS-2 exhibited stable performance while CIGS-1 and CIGS-3 exhibited degradation. CIGS is known to be stable over long periods of time, and thus the possible reasons for the degradation of the two modules are discussed.