Estimation of Diffuse Solar Radiation in the Region of Northern Sudan

Abstract

Information of diffuse solar radiation at a given location is essential for study and designing solar energy systems. However, many places around the world, like region of Northern Sudan, have no measurement for this solar radiation component. In this study, seven new empirical models have been developed for estimation of monthly average daily diffuse solar radiation on a horizontal surface in the region of Northern Sudan. Data of global solar radiation and sunshine hours recorded at two stations located within the region has been used. Performance of new developed models has been evaluated by using different statistical indicators. Results revealed that the models based on clearness index showed better performance than the models based on sunshine fraction. However, the hybrid model (model M 24) developed on the basis of both clearness index and sunshine fraction, expressed the highest performance. Consequently, this model is recommended to assess diffuse solar radiation in the region under consideration. Furthermore, it can also be applicable to adjacent sites that possess the similar climatic conditions and lack measurement for diffuse solar radiation.