ESTIMATING GLOBAL SOLAR RADIATION USING SURFACE TEMPERATURE AND SUNSHINE DURATION OVER SELECTED STATIONS IN NIGERIA

Abstract

This research work is aimed at estimating solar radiation using surface temperature and sunshine duration for Gusau, Abuja and Ikeja. The global solar radiation on horizontal surface at the location of interest is the most critical input parameter employed in the design and prediction of the performance of solar energy devices. In spite of its importance, its measurements are not frequently available especially in developing countries. From maximum, minimum temperatures, sunshine hour and monthly mean global radiation data for Gusau, Abuja and Ikeja, for a period of 1980 – 2010, ten (10) correlation equations from univariable and multivariable Angstrom’s type equations have been produced for the years and the periods of dry and wet seasons. Four (4) other models were also tested for to see the best performer with the estimated global radiation. From these, it was deduced that the Glower and Mcgulloch model has the overall best performance according to MBE and RMSE values for all the stations. More so, the equations combining temperature parameters performed best for Ikeja, Gusau and Abuja in that order, while the models performed best for Gusau, Abuja and Ikeja in that order. It was also noticed that the coefficients of correlation and determination were lower for the wet (rainy) season than the dry season for Gusau and Ikeja which is in agreement with the work of (Okogbue and Adedokun, 2002) for Ondo, while higher values were noticed for the wet season than dry season for Abuja which is in conformity with the work of (Okundamiya and Nzeako, 2009). This implies that estimation of solar radiation depends more on those parameters in the dry season than in the wet season for Gusau and Ikeja while depending more on the parameters in the wet season for Abuja, and more so, the estimation of solar radiation is seasonal dependence.