Medium-Term Degradation of Different Photovoltaic Technologies under Outdoor Conditions in Alpine Area

The assessment of module degradation is a key factor for the development of the photovoltaic market. Investors and utility companies need to accurately predict the energy production of PV systems in the long-term, manufacturers need to improve the reliability and durability of their products. Degradation rates warranted by manufacturers are estimated through accelerated indoor tests, even though module technology and manufacturing processes are not the only factors affecting module durability over the years: climatic and weather conditions at the PV system location must be adequately taken into consideration. For this reason, many studies in the past processed outdoor PV monitoring data to assess the degradation rate. This work focuses on the evaluation of degradation rates of different PV technologies installed at the Airport Bolzano Dolomiti (ABD) test plant, monitored by EURAC: monocrystalline silicon (mc-Si), polycrystalline silicon (pc-Si), amorphous silicon (a-Si), micromorph silicon (a-Si/μc-Si), Cadmium Telluride (CdTe) and Copper Indium Gallium Selenide (CIGS). The second and third year of plant operation are considered, in order to evaluate the medium-term degradation process. Three different methodologies: PVUSA, Performance Ratio and Maximum Power at Standard Test Conditions are employed and the results compared.