Use of HR Meteosat images for the mapping of global solar irradiation in Tunisia: preliminary results and comparison with Wefax images

The evaluation of the incident solar energy on a given site becomes at the present time, one of the needs of the users and the manufacturers of energetic solar systems. For this purpose, we have developed, in collaboration with the Energy Climate Laboratory of Avignon University (France), an assessment method (GISTEL) of solar irradiation using Meteosat satellite images. We have shown in previous papers (Ben Djemaa A, Delorme C. Solar Energy 48(5) 1992 325; Chaabane M, Ben Djemaa A, Kossentini A. Solar Energy 57(6) 1996 449) the simplicity and efficiency of the GISTEL method to estimate global solar irradiation and its convenience compared with B2 and Wefax images. Herein we describe briefly our method and present the preliminary results obtained from a series of high resolution (HR) Meteosat images. The results are compared with values obtained at eight Tunisian meteorological stations and are then compared with the results obtained using Wefax images. A statistical study of the errors between estimated and measured values is presented and analysed. We also show the efficiency of the map-form of solar energy data for Tunisian territory and its potential for future studies. For Tunisia and African countries, these images present the best means for solar studies since they cover the quasi-totality of the African continent with a good temporal and spatial resolution. (C) 2001 Elsevier Science Ltd. All rights reserved.