Long-term degradation assessment of a 2 MW floating solar photovoltaic plant in a humid subtropical climate using time-series analysis

Abstract

This study evaluates the long-term performance and degradation of a 2 MW floating solar photovoltaic (FSPV) system operating in the humid subtropical climate of Northwest India. Analysis was based on 24 months of SCADA data, including irradiance, energy generation, ambient temperature, and key performance metrics such as reference yield (Y_R), final yield (Y_F), performance ratio (PR), capacity factor (CF), and system efficiency. The system recorded an average PR of 71.83% and CF of 18.62%, both showing a gradual decline over time. Four statistical methods are Linear Least Squares, Classical Seasonal Decomposition, Holt-Winters, and Seasonal-Trend decomposition using Loess (STL), were used to estimate degradation. Annual degradation rates ranged from 0.70% to 2.15%, with STL providing the most robust estimate of 0.70% ± 0.16%. The findings underscore the climatic resilience of FSPV systems and the importance of real-time monitoring with advanced statistical methods. This marks India’s first SCADA-based, long-term FSPV degradation study.