New model to estimate daily global solar radiation over Nigeria

This study focussed on developing an appropriate model for estimating daily global solar radiation for any location in Nigeria. Data for the study were obtained from the Nigeria Meteorological Agency, covering 12 sites, spread across the six geopolitical zones, for a period between 1987 and 2010. Various statistical methods were employed to determine the performance and accuracy of the model. A multivariate model that expresses global solar irradiance in terms of location latitude, daily relative sunshine, maximum daily temperature, daily average relative humidity, and cosine of day number was developed. The inclusion of the maximum daily temperature and daily mean relative humidity makes the model much more sensitive to climatic and weather changes. Also, the seasonal fluctuations of the humid tropical region are also well captured in the model. The analysis showed a good agreement between the measured data and computed results. Thus the model can be used to predict the global solar irradiance over Nigeria with minimum error. Further to this, the global solar radiation intensity values produced by this approach can be used in the design and estimation of the performance of solar applications. (C) 2013 Elsevier Ltd. All rights reserved.