Global solar radiation estimation based on sunshine duration at plateaus zone, China

A total of 12 models in linear quadratic, cubic, exponential and power forms using only sunshine hours, latitude, and altitude were developed and compared to estimate the daily global solar radiation on a horizontal surface for 6 weather stations at plateaus zone, China. The models were compared on the basis of statistical error tests using the root mean square error (RMSE), mean bias error (MBE), and adjusted coefficient of determination (R₂). For each individual station, the errors resulting from the better equations are such that R₂ lies between 73.039% in Lasa and 92.871% in Geermu, MBE is under 0.162(MJ/m₂) in Yushu and RSME does not go beyond 3.073(MJ/m₂) in Lasa. A general equation was established for the plateaus zone, and the R₂, MBE and RSME values vary from 84.74% to 85.10%, from -0.3747 to 0.0396 (MJ/m₂) and from 2.7224 to 2.7739 (MJ/m₂) respectively. Results show that the present model can be recommended in engineering practice with adequate accuracy.