A power prediction model and its validation for a roof top photovoltaic power plant considering module degradation

Abstract

In this study, power generation prediction of a photovoltaic(PV) power plant is carried out using a new solar cell model which also include power degradation of aging modules. The solar cell parameters are measured using a class A Sun simulator to determine PV degradation. The predicted results are validated experimentally using automatic data monitoring system under real outdoor conditions. The model with three-parameters, is found to be more accurate with least mean absolute percentage error 3.7% under low solar irradiance range. The results for four and five parameter models are found to be more precise in medium (150–500 W/m2) and high (>500 W/m2) solar irradiance ranges with mean absolute percentage error of 5.4% and 4.21% respectively. The results show 2% decrement in maximum power of PV plant after 4 years of its installation due to module degradation. The results are also compared with previous models which show the present model has higher accuracy of about 26%. The impact of series and shunt resistances at different irradiance levels, is also discussed. The results reveal that present model after including degradation can predict the real output power of a PV system more accurately. Follow up research areas are also identified.