With increasing interest in renewable energy good quality solar radiation data is becoming-increasingly important, particularly the direct component, with regard to electricity-production (photo-voltaic systems) and thermal energy (solar collectors). Greatest amount of solar energy is available in two broad band's encircling the Earth between 15-35N deg latitude north and south. Iraq is situated between 29-37N deg latitude north, so it has good solar energy potential. There are great opportunities to construct projects that invest the solar energy for electric power generation in Iraq, which requires providing models specialized in locating the spatial and temporal distribution of the incident solar radiation on the inclined surfaces to provide more solar energy, Usually data of solar radiation are measured for horizontal surfaces, but in this research we deals with the issue of converting those data to solar radiation incident on inclined surfaces.