Estimation of Global Solar Radiation using Sunshine and Temperature based Models in Makurdi, North-Central, Nigeria
Pages : 438-446, DOI: https://doi.org/10.14741/ijmcr/v.8.3.14Download PDF
Precise knowledge of solar radiation distribution at a particular geographical location is of great significance for the development of solar thermal and photovoltaic energy devices. The monthly mean daily data for global solar radiation and sunshine hours for a period of ten years for Makurdi (Latitude 7.7322°N, 8.5391°E) were obtained from the Nigerian Meteorological Agency, and used to develop a number of first order Angstrom-type correlations. The regression constants of ‘a’ and ‘b’ in Angstrom-page equation were found to be 0.273 and 0.558 respectively. Maximum and minimum measured monthly mean global solar radiations were 20.09 and 13.25MJ/m2/day which occurs in the months of November and August respectively. Estimated monthly clearness index and monthly sunshine duration were used in modeling four temperature-based and two sunshine-based models. Estimated values of global solar radiation by the various models and the measured solar radiation were tested using statistical tools of mean bias error (MBE), root mean square error (RMSE), mean percentage error (MPE), relative root mean square error (RRMSE), coefficient of residual mass (CRM), and Nash–Sutcliffe Coefficient (NS). The values of coefficient of determination (R2) were also determined for each developed equation. Comparing these models, it was observed that the Louche model equation performed better in terms of coefficient of determination (R²) and least values of MBE, RMSE, MPE, and CRM while, HargreavesSamani model have the least R².
Keywords: Solar Radiation, clearness index, sunshine hours, regression constants and statistical tools