Abstract: Solar radiation data are important tools for many areas of research and applications in various engineering and scientific fields including for example climatology, agro meteorology, hydrology and solar energy converting system design. The main objective of the present study is to predict the daily solar radiation and the hourly irradiation on a horizontal surface for the city of Gabès located in the south east of Tunisia. The obtained results are used to develop a Matlab program which can be used in the estimation of the solar radiations for all the city of Tunisia.

Key words: solar radiation, solar energy, daily solar radiation, hourly solar irradiation.