Outdoor stability performance of thin-film photovoltaic modules at SERI

Tests of the outdoor stability performance of one set of commercially available amorphous silicon (a:Si) modules, one tandem a:Si research submodule, two copper indium diselenide (CIS) modules, and one cadmium telluride (CdTe) test structure are reported. The test data show that stability characteristics of amorphous silicon devices exhibit about 20-25% degradation in performance over an extended period of testing (over 4 yr). Most of the performance degradation in amorphous silicon modules is due to the Stabler-Wronski effect and occurs in the first several months. The module performance is essentially stable after the initial light-induced degradation. CIS and CdTe material devices exhibited none or little degradation, over the initial testing period of several months