Estimation and Comparison of Various Global Solar Radiation Models on Horizontal Surface in a Hot and Dry Region

Abstract

In this study, 54 empirical models including 22 new models were used to estimate the global solar radiation on horizontal surface. The data were collected in Dohuk cities in the northern Iraq. The evaluated models are based on sunshine duration, air temperature, cloud cover, and other meteorological parameters. In the investigated region, the statistical error indicators value for all empirical models of R, R-2, mean absolute bias error, root mean square error, mean absolute percentage error, Nash-Sutcliffe equation, and t-test value were low and within an acceptable range. The results of Model 49 based on the other meteorological parameters which is newly developed model with equation H/H = H a+b in triangle T+C(T-min /T-max) + dRH had the most appropriate result with a value of R-2 (0.9942) in the 54 empirical models. Besides, 22 new equation models are produced based on sunshine hours, air temperature, and other meteorological parameters. The best accuracy among the new equation was observed in Model 49. Furthermore, the Models 34, 12, and 25 based on cloud cover, sunshine hour, and air temperature in terms of data accuracy were ranked, respectively.