The article suggests the method for calculating the solar radiation on a horizontal surface of the territory of Syria which has been developed using the weather database of NASA and ArcGIS software to create the atlases of Syria. In order to compute the solar radiation on an inclined surface for Syria, the following steps were taken. Firstly, the method proposed by Liu and Jordan (1962) and developed by Klein (1977) was used and applied at a point with a latitude of 33º and a longitude of 36º in Syria to calculate the total average daily monthly and yearly solar radiation on an inclined surface and its components (direct, diffuse and ground reflected). Secondly, the annual and monthly values of the optimal tilt angle of the solar panels were determined. Thirdly, verification of reliability and accuracy of calculations was carried out. Finally, using the interpolation method (inverse distance weighted IDW) in ArcGIS, the method proposed was applied to 63 points that covered the territory of Syria. Thus, we developed an Atlas of Syria of solar radiation on an inclined surface which characterized by the optimal tilt angles of solar panels and the maximum annual solar radiation on an inclined surface under these angles. Solar Radiation Atlas of Syria shows that the annual optimal tilt angle of the solar panels varies in the range from 23º to 28º and the maximum average annual solar radiation on an inclined surface under these angles varies in the range from 1859 to 2069 kWh/m2·year. In addition, on the basis of the NASA meteorological database, we determined the average total gross (natural) potential of solar energy on optimal inclined surfaces in Syria which is 362.1·103 TWh per year.
Diagnosing model errors in simulation of solar radiation on inclined surfaces
