Combination of Indoor and Outdoor Measurements for the Identification of Degradation Trends in PV Modules

Tunnel oxide passivated contact (TOPCon) photovoltaic (PV) modules are gaining significance in the photovoltaic industry due to their high efficiency. However, concerns about their reliability – particularly regarding moisture ingress and ultraviolet (UV) radiation resistance – persist. This study presents a methodology that combines existing indoor and outdoor measurement approaches to investigate specific degradation mechanisms in TOPCon PV modules, along with a comparative analysis against HJT and PERC technologies. The modules underwent accelerated aging testing involving either damp-heat or UV exposure, followed by outdoor exposure alongside non-aged samples. This approach provided insights into the severity of moisture ingress and its effects on the increase in series resistance and the reduction of fill factor. Additionally, we identified the reduction of V_OC as the primary mechanism driving performance decline during UV aging and validated the stabilization behavior in the laboratory, which is equivalent to day/night cycle conditions. Overall, this study enhances our understanding of the degradation processes affecting PV modules and their implications for long-term reliability.