The first disaggregated solar atlas of Djibouti: A decision-making tool for solar systems integration in the energy scheme
Résumé
The aim of this study is the creation of the first solar atlas in Djibouti, including assessment and improvement, for helping to establish an energy planning. To realize this atlas, a satellite-based irradiance model is used (EUMETSAT O&SI SAF). To validate this model over Djibouti, we installed 2 pyranometric weather stations during the year 2010 and we compared hourly, daily and monthly irradiation estimates against ground measurements. Results showed a good agreement between measurements and estimates, with, for the whole hourly sets, an RRMSE equal to 10.88% and 15.29%, and a bias of 0.61% and −2.17%. To improve accuracy of irradiation estimates, we then disaggregated irradiation maps with a 3 arc second (∼ 90 m at the equator) Digital Elevation Model (DEM), in order to take into consideration topography and elevation effects. As current software does not allow downscaling of pre-processed maps, we performed this work by computing our own global model, combination of horizon, elevation correction and irradiance splitting models. By comparing horizon estimates against measured horizons, we observed that error probability on irradiation increased over high mountainous areas, mainly due to the original DEM error. According to the final computed atlas, during the year 2010, mean irradiation all over the country was around 2100 kWh/m² and about 82% of the country received over 2000 kWh/m².
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