Estimating daily global solar radiation by day of year in China

In this study, a new empirical model is proposed for estimating daily global solar radiation on a horizontal surface by the day of the year. The performance of the proposed model is validated by comparing with three trigonometric correlations at nine representative stations of China using statistical error tests such as the mean absolute percentage error (MAPE), mean absolute bias error (MABE), root mean square error (RMSE) and correlation coefficients (r). The results show that the new model provides better estimation and has good adaptability to highly variable weather conditions. Then the application of the methodology is performed for the other 70 meteorological stations across China.