Assessment of the Solar Resource in Andean Regions by Comparison between Satellite Estimation and Ground Measurements: Study Case of Ecuador

To develop and implement solar technologies, it is necessary to know accurately the solar resource on the place. Consequently, several institutions working in renewable energy have made efforts to both measure solar radiation and develop models to estimate solar radiation. The main drawback with estimations is their lack of accuracy. Recently, the NREL (NSRDB) has update its meteorological database based in satellite estimations. Some validations have been reported, however, no studies about its validity for the Andean region have been done. In this work, measurements of global horizontal irradiation (GHI) from 53 stations placed along the Ecuadorian territory were compared with satellite estimation data from NSRDB. Statistical descriptive indicators of dispersion (RMSE, MBE) and goodness of fit (KS test) were used. The data were grouped in hourly, daily, weekly and monthly basis, as well as in clear and cloudy basis. Results show that monthly grouping may be used with confidence, since close to 95% of comparisons have a good fit. Also, results show that both, clear sky and cloudy models tend to overestimate solar radiation in such a region. Solar resource seems to be high in Ecuador since more than 75% of the territory has values over 3.8 kWh/m2day.