The purpose of this work is to give the potential of solar energy in Medina (Kingdom of Saudi Arabia). We develop a correlation between the different parameters of solar energy. We have used a database available at the National Renewable Energy Laboratory (NREL) website for five years since 1998 until 2002. Also, a typical meteorological year (TMY) has been built from this database. By using the correlations model obtained from these database, we can estimate the global and diffuse irradiation with good agreement in Medina. The correlation connecting diffuse irradiation with both clearness index and sunshine (SS) duration is found to be applicable in Medina site. A linear correlation between ambient temperature and global irradiation data is found from sunrise until midday with a good agreement. A polynomial correlation is given between temperature and global irradiation data from midday until sunset. (c) 2007 Elsevier Ltd. All rights reserved.