Performance and Degradation Assessment of PV Modules Exposed to Short-Term Outdoor Conditions in Two Distinct US Climatic Zones

Current research focuses on the performance degradation of photovoltaic (PV) modules, examining both crystalline silicon (p-Si and m-Si) and thin-film technologies, including a-Si/c-Si, HIT, CdTe and CIGS. These modules were operated outdoors in two distinct climatic zones in the United States (US) over a period of three years. The degradation analysis includes the study of various quantities, such as the decrease in peak power, the reduction in current and voltage, and the variation in the fill factor. The annual degradation rate (DR) of PV modules is obtained by a linear fit of the effective maximum power evolution over time. The results indicate that m-Si and p-Si modules experienced a slight decrease in performance, with DRs of −0.83% and −1.07%, respectively. Subsequently, the HIT module exhibited a DR of −1.75%, while CdTe and CIGS modules demonstrated DRs of −2.03% and −2.45%, respectively. The a-Si/c-Si module showed the highest DR at −3.26%. Using the Single Diode Model (SDM), we monitored the temporal evolution of physical parameters as well as changes in the shape of the I-V and P-V curves over time. We found that the key points of the I-V curve degrade over time, as do the I-V and P-V characteristics between two days approximately 30 months apart.