Forecasting degradation rates of different photovoltaic systems using robust principal component analysis and ARIMA

Degradation rates based on forecasting of performance ratio, R-p, time series are computed and compared with actual degradation rates. A 3-year forecasting of monthly R-p, measured from photovoltaic ( PV) connected systems of various technologies is performed using the seasonal auto-regressive integrating moving average ( ARIMA) time series model. The seasonal ARIMA model is estimated using monthly R-p measured over a 5-year period and based on this model forecasting is implemented for the subsequent 3 years. The degradation rate at the end of the forecasting period, eighth year, is computed using a robust principal component analysis based methodology. The degradation rates obtained for various ( PV) systems are then compared with the ones obtained using the actual 8-year data.