estimation of global and diffuse solar radiations for se-lected cities in nigeria

in this study, estimation of global and diffuse solar radiations of selected cities in nigeria was carried out to assess the feasibility of solar energy utilization. the results of this work show the variation of direct and diffuse component of solar radiation in summer and winter months. the contribution of diffuse solar radiation is high during the monsoon months whereas sky conditions are clear during winter months. from the estimated values it was found that solar energy can be utilized very efficiently throughout the year in sokoto and ilorin. the clearness index which is availability of global solar radiation varies with geographical location and period of the year. clearness index in the cities studied varies from 0.303 to 0.683. the least clearness index is in port- harcourt (0.303) in the month of july and the highest value is 0.683 in sokoto in the month of march. the values of the global solar radiation estimated in the selected cities vary from 12.67 - 20.72 mjm-2day-1 in abeokuta, 15.17 - 22.90 mjm-2day-1 in ilorin, 10.75 - 19.03 mjm-2day-1 in port harcourt and 19.08 - 25.71 mjm-2day-1 in sokoto. the data reveal that there is an evi-dent increase of the value of the global solar radiation from south to north. this was expected as the rad-iation should increase as one move to the equatorial line. this study shows that the availability of solar energy in the selected cities varies and generation of electric power from solar energy in nigeria is viable.