Testing the Performance of Some Empirical Models for Estimating Global Solar Radiation Over Makurdi, Nigeria.

Abstract

The performance of both temperature and sunshine dependant models were evaluated for the estimation of global solar radiation for Abuja, Nigeria. The variations of the mean monthly, annual temperatures and extraterrestrial solar radiation were estimated and the monthly global solar radiation (R_s) was estimated over eleven years (1990 - 1991, 1995-2003), using three different models: Angstrom (1924), Hargreaves and Sammani (1982) and Garcia (1994) models. Using a performance indicator (standard deviation), the regression constants were obtained for the Angstrom and Garcia models as a = 0.461 and b = 0.605respectively. The estimated solar radiation (R_s) was tested statistically by calculating the standard deviation (SD) to determine which model is more suitable for the simulation of global solar radiation in Abuja. The lowest SD of 1.25, 2.19 and 2.56 were obtained for Hargreaves - Sammani (1982) ; Angstrom (1924) and Garcia (1994) respectively indicating that Hargreaves and Sammani temperature dependent model is more suitable for the simulation of global solar radiation in Abuja and other locations with similar latitudinal variations.

Keywords: Temperature, sunshine hour, sunshine duration, global solar radiation, clearness index