A COMPARISON OF THREE MODELS FOR ESTIMATION OF GLOBAL SOLAR IRRADIATION ON TILTED AND ORIENTED SURFACES IN ATHENS

Abstract

Solar radiation data from one location in Greece (Athens), are used to test the applicability of three models for computing global irradiance on tilted surfaces. The models selected for discussion, applicability, and comparisons are the model suggested by Liu and Jordan dated 1962, the model of Klein dated 1977, and the model of Klein and Theilacker dated 1981. All these three models are applied, tested and compared for their reliability. The comparative study of the models shows that all these models are rather accurate for locations in Greece. But it seems that the Klein and Theilacker's analytical method for estimating leads to better results, values calculated in this manner and through the other methods are compared. Therefore, the above three models are used to estimate global solar irradiation for one location on surfaces of various tilt angles and azimuths, and the results are presented and discussed.