PV module degradation analysis and impact on settings of overcurrent protection devices

Degradation of photovoltaic (PV) modules is inevitable regardless of the size of a PV plant. While it is understood that degradation leads to a reduction in power generation, the effects of module degradation on PV plant protection system remains somewhat unclear. Considering that most of the PV plant protection system settings are based on modules in good conditions without degradation, it is imperative to evaluate the effect of module degradation on fault detectability by conventional protection infrastructure to ensure safety and reliability of PV plants. The purpose of this paper is to investigate the relationship between the levels of module degradation and PV plant faults including fault current levels, fault locations and types of faults. An experimental setup comprising of 16 modules of varying degradation levels is used to generate multiple short circuit fault scenarios. The results indicate that degradation results in a decrease in string current, which may lead to an increased likelihood of fault undetectability using conventional protection settings.