Development of energy model based on total daily irradiation and maximum ambient temperature

To predict the energy produced by photovoltaic modules under certain meteorological conditions, an energy model can be used. Existing energy models need parameters that are not always available. In this study, an energy model based on regression analysis of total daily irradiation and maximum daily ambient temperature is developed. This model is able to predict daily module energy based on these two parameters only. The data used in this study were collected over a 15-month period at the University of Port Elizabeth (UPE), South Africa. The developed model was first compared to two existing energy models using data collected over the month of October 1998. Its validity was then evaluated over the entire 15-month period using seasonal regression coefficients. An application of the model to predict module energy output is illustrated by using data collected at the South African Weather Bureau (SAWB), Port Elizabeth (PE) station. The predicted energy is then compared to the energy measured at UPE. Results obtained show that the developed model is valid and a good predictor of module energy.