Solar energy is an important power source for surface-based operation on Mars. Photovoltaic cells offer many advantages. Detailed information on solar radiation characteristics on Mars are necessary for effective design of future planned photovoltaic systems. In this article we present analytical expressions for solar radiation calculation and solar radiation data for inclined stationary flat surfaces for Mars as functions of day, latitude, and atmospheric dust load (optical depth). The diffuse component of the solar radiation on Mars due to the atmospheric dust can be significant, thus greatly affecting the optimal inclination angle of the photovoltaic array. The yearly optimal inclination angle for atmospheric optical depths measured by the Viking landers resulted in much smaller angles than the local latitudes.
