Regional Estimation of Solar Radiation using Routinal Meteorological Variables

Abstract

In this paper, the monthly surface data of solar radiation, minimum and maximum temperatures, wind speed and evaporation of 1970-1995 for four climatic regions in Nigeria were obtained from the archives of Nigerian Meteorological Agency (NIMET), Oshodi, Lagos. The distributions of solar radiation with each of the four meteorological variables were observed. It was found that solar radiation was well monitored by each of the variables indicating that the linear combination of the variables can be used to develop model from where solar radiation data can be evaluated. Consequently, the multivariate linear regression model was developed using 1970-1990 data of the five meteorological parameters for each of the four regions taking solar radiation as dependent variables and the four other meteorological variables as independent variables. The models were validated using 1991-1995 data of minimum and maximum temperatures, wind speed and evaporation to obtain the predicted solar radiation. Analyses have shown that over seventy percent correlations exist between the measured and estimated values of solar radiation. The efficiency of the developed models was further verified by calculating the values of R ², MBE, RMSE and t-test at confidence level of p < 0.05. The results obtained showed that the models were statistically significant and could be used to estimate solar radiation at the regions in Nigeria.

Keywords: Distribution, Meteorological, Multivariate, Radiation and Statistically.