The incident solar radiation can be measured by ground-based meteorological stations or meteorological satellites and/or be estimated through models. There are several solar models available in the literature. They vary in the detail of the input parameters and, consequently, in the output map. Solar Analyst (Fu & Rich, 1999) and Photovoltaic Geographical Information System (PVGIS) (Šúri, Huld, & Dunlop, 2005) are two examples of solar radiation models.