Performance and degradation assessment of large-scale grid-connected solar photovoltaic power plant in tropical semi-arid environment of India

The performance and degradation of a 1 MWp utility-scale photovoltaic (PV) system located in the tropical semi-arid climate of India is investigated based on four years of monitored data. The reference yield, final yield, system efficiency, capacity factor, and performance ratio are 4.64 h/day 6.23 h/day, 11%, 19.33%, and 74.73%, respectively, according to the standard IEC 61724. The performance is compared to other large-scale PV systems in different climate conditions. The degradation of the PV plant is quantified by using various statistical methods. These methods include the linear least-squares regression (LLS), the classical seasonal decomposition (CSD), the Holt-Winters seasonal model (HW), and the seasonal and trend decomposition using loess (STL). The degradation rate is estimated at 0.27%/year, 0.32%/year, 0.50%/year, and 0.27%/year, respectively, after 50 months operating period. The degradation accuracy analysis classifies the LLS and HW as lower accuracy methods (0.22%) than CSD (0.11%) and STL (0.15%). A comparison of the degradation of mono-Si PV systems for various locations is performed using different statistical methods. This study contributes to the improvements in the knowledge of PV degradation in the Indian climate.