Estimating solar radiation in Ikeja and Port Harcourt via correlation with relative humidity and temperature

Abstract

Relative humidity and temperature data are more readily available to obtain from observatories than sunshine hour data. In this work, 10 years (1986–1987, 1990–1997) monthly average measurement of relative solar radiation, daily temperature range, relative humidity and the ratio of minimum to maximum temperature were used to establish the coefficient of eight models for estimating solar radiation in Ikeja and Port Harcourt. Coefficient of correlation (R), Mean Bias Error (MBE), Root Mean Square Error (RMSE), Mean Percentage Error (MPE), t-statistic and the rank score were used as performance indicators. In Port Harcourt, the equation producing the best result with MBE, RMSE, MPE and t-statistic value of −0.1078, 0.9850, −0.4373% and 0.3653, respectively, is given by: Rs/Ro = 3.266 − 0.306(RH)0,5. In Ikeja, the equation producing the best estimation with MBE, RMSE, MPE and t-statistic value of 0.1590, 1.0110, 2.0559% and 0.5281, respectively, is given by: Rs/Ro = 2.042 − 2.136(θ).