New model to estimate monthly global solar radiation from air temperature in Algeria

Global solar radiation is an important parameter in the study of any solar energy project. Global solar radiation measurements are not operational in all cities of Algeria, due to high cost of acquisition, maintenance and technical complexities. To overcome this problem the use of empirical models based on temperature as an interesting and accessible parameter is necessary. In this study, six empirical models namely; Hargreaves and Samani model, Chen model, Li 1 model, Li 2 model, Bristow and Compbell model and Okonkwo model, have been selected from literature to estimate monthly global solar radiation from air temperature data of Djelfa. The city of Djelfa (Algeria) is taken as the sole case of study. The performance of those models was evaluated through several statistical indicators (R
²
, RMSE, MBE, MPE and RPE). The results show the superiority of Li 2 model on the studied models. Based on the evolution of monthly global solar radiation as function of extraterrestrial radiation and air temperature variation, a new model was developed. Comparison between model 4 and the developed one indicates the superiority of the new model. This model has been verified for other Algerian cities such as Biskra and Ghardaia. The data of these regions (global solar radiation, maximum and minimum air temperature) were taken from NASA site web. The results show also the superiority of this new model for these two regions. Therefore, the developed model can be suggested to estimate monthly global solar radiation using only air temperature.