Assessing the performance of global solar radiation empirical formulations in Kampala, Uganda

Summary

Solar radiation incident on the Earth’s surface is a determining factor of climate on Earth, hence having a proper solar radiation database is crucial in understanding climate processes in the Earth’s atmosphere. Solar radiation data may be used in the development of insolation maps, analysis of crop growth and in the simulation of solar systems. Unfortunately, measured solar radiation data may not be available in locations where it is most needed. An alternative to obtaining observed data is to estimate it using an appropriate solar radiation model. The purpose of this study is to assess the performance of thirteen global solar radiation empirical formulations, in Kampala, Uganda, located in an African Equatorial region. The best performing formulations were determined using the ranking method. The mean bias error, root mean square error and t-statistic value were calculated and utilized in the ranking process. Results have shown that the formulation: ${\bar H}/{\bar H }_0 = a + b({\bar S}/{\bar S} _0 ) + c( {\bar S } /{\bar S} _0)^2$ is ranked the highest and therefore is the recommended empirical equation for the estimation of the monthly mean global solar irradiation in Kampala, Uganda and in other African Equatorial locations with similar climate and terrain.