Estimation of global solar radiation, sunshine hour distribution and clearness index in Enugu, Nigeria

Abstract

The concept of solar energy and its applications in this present day world would come to be one of the solutions to our present Nigerian problem of instability and epileptic power supply. In the study, the baseline data for mean monthly sunshine hours (S ) and global solar radiation (H) for Enugu (6.70N, 7.60E) were obtained from the Nigeria Metrological Agency (NIMET), Oshodi Lagos Nigeria and spanned 1996 to 2010. The data for global solar radiation were measured with a Gunn-Bellani radiometer. The average sunshine hour for the period of study was estimated to be 5.67 hours; the Angstrom constants a and b of Angstrom-type correlation used in estimating monthly average global solar radiation was estimated to be 0.27 and 0.58 respectively; a linear regression correlation model was developed for Enugu. The result of global solar radiation was found to be 14.44 −2 −1 MJm day thereafter subjected to statistical tests [MBE , RMSE , MPE ] and proved to be good estimates with previous literatures reviewed. The value of clearness index ( ) KT was estimated to range from 0.43 to 0.61 showing Enugu as so a partly clear sky city.