Estimating global solar radiation using common meteorological data in Akure, Nigeria

In this study, the global solar radiation on horizontal surface in Akure, Nigeria (Latitude 7.25° N and Longitude 5.2° E) using 22-year data (July 1983–June 2005) was analysed. Simple empirical correlations for evaluating the monthly average daily global solar radiation were developed. The calculated monthly clearness index values indicates that prevailing weather condition in Akure is partly overcast but can become heavily overcast during the months of July–September. The Angstrom–Page correlation predicted the monthly average daily global solar radiation better than the other correlations developed in this study. However, in the absence of the sunshine hour data, it was found that temperature only based correlations (especially the average temperature based correlation) and precipitation based correlation can be used to predict the global solar radiation within reasonable level of accuracy in Akure. The correlations presented in this study could be applied to locations with comparable weather condition to Akure.