Evaluation of optimal model for estimating solar radiation in a moderate and mountainous area based on climatical data (Case Study: Kermanshah, Iran)

The solar radiation received by earth surface is one of the most applicable parameter that is usable in hydrology, agriculture, architecture and passive houses , climatology and meteorological modeling. Many different experimental equations had been suggested by researchers to estimate this parameter in different climates. This study aimed to calibrate existing model and develop a new model for estimating global solar radiation data using commonly and available measured meteorological records such as two well-known solar radiation models Angstrom-Prescott and Allen were calibrated and eight new empirical global solar radiation models were developed. Three statistical parameters Root Mean Square Error (RMSE), Nash-Sutcliffe equation (NSE) and Mean Bias Error (MBE) have been used to estimate error and model validation. The results showed that, the value of RMSE, NSE, MBE and Rs2 for Rs3 model got the highest rank with 44.59, 43.36, 594.92 and 0.9933, respectively. All models were calibrated based on available meteorological data and sunshine hours and validated using daily measured solar radiation data in (2008–2015) at meterological station of Kermanshah city located at the west of iran.