ISSN 2360-7955
Abstract: This paper described how an empirical model originally formulated by Hargreaves – Samani to compute the monthly global solar radiation has been modified to make it fit Barkin Ladi’s environs. The study was undertaken to estimate the global solar radiation in Barkin Ladi, Plateau State, Nigeria; Latitude 9.5oN and Longitude 8.9oE. The solar radiation and maximum and minimum temperatures for a period of 10 years (2011-2020) were obtained from Yakubu Gowon Airport Meteorological Unit, Heipang. The corresponding monthly value of extraterrestrial solar radiation (Ho) was calculated for each data. Three models based on the meteorological variables were generated and validated using daily data in 2011-2020. The performance of each of the models was evaluated based on the coefficient of determination (r2), mean bias error, (MBE), Root mean square error (RMSE) and mean percentage error (MPE). The Hargreaves -Samani model with linear regression has the highest r2-value of 0.76 and lowest MBE, RMSE and MPE values of 2.81 w/m2, 1.46 w/m2 and -6.42% respectively. The analysis showed that the best performance for the present data set was found at the Hargreaves-Samani model with linear regression followed by H-S model with power regression and the original H-S model. The H-S model is simple and recommended for estimating the daily global solar radiation when only temperature data are available. Based on the overall results, it was concluded that the meteorological-based method provides reasonably accurate estimates of global solar radiation for the environs where coefficients of the model were developed.
Keywords: Estimation, Global Solar Radiation, Extraterrestrial radiation, temperature, Barkin Ladi, Nigeria