Overirradiance effect on the electrical performance of photovoltaic systems of different inverter sizing factors

Abstract

The optimization of the installation characteristics of photovoltaic (PV) generators guarantee greater generation of electric energy and a better distribution of solar irradiation of the PV modules; on the other hand, to determine the sizing factor- SFI, one must take into account the saturation losses of the AC output during conditions of high irradiance and overheating of the inverters. Based on the behavior of the measured solar irradiance, there are several rapid oscillations, and over the days, most of the measured curves are superior to the clear sky model, caused by a transient effect of the atmospheric boundary layer. Two photovoltaics systems–SFCR, were analyzed using the same model and inverter power but with a different inverter design factor. The SFCR were installed in southern Brazil 30 km apart. According to the inverter operating temperature monitoring data, it was also possible to prove the occurrence of the overtemperature to which the inverter with lower SFI is subjected, reaching operating temperatures on the order of 80 °C. SFCR A had higher solar radiation of 4.2% over the year compared to SFCR B; however, SFCR B had a higher final yield of 11.86%. In this way, PV systems with undersized inverters will be losing electricity generation, in addition to reducing their useful life due to component stress, resulting in inverter changes over the life of the PV system.