Modeling the spatial distribution of Global Solar Radiation (GSR) over Ghana using the ˚Angström-Prescott sunshine duration model

Abstract

Solar radiation is an important geological and meteorological parameter. In most devel- oping countries, data is readily unavailable owing to lack of instrumentation and skilled personnel. In this study, Global solar radiation (GSR) over Ghana has been quantified us- ing the ˚Angström–Prescott sunshine model with sunshine duration data from 22 synoptic stations distributed across the country’s ecological zones. The simulated data was gridded at 10 km by 10 km, establishing the spatial distribution of solar radiation over the country. Comparison with satellite data showed good results with root mean square error (RMSE) values of 1–5 MJm −2 day −1 and correlation coefficient of 60 - 66%. Meanwhile, the esti- mated total GSR over the country was found to be 412.82 MJm −2 day −1 . The savanna zone had the maximum estimated total monthly mean GSR for the year, with the highest value of 20.76 MJm −2 day −1 in Navrongo. The forest zone had the minimum estimated total an- nual mean GSR, with the lowest radiation level in Oda (17.11 MJm −2 day −1 ). A maximum and minimum mean clearness index of 0.59 and 0.48 respectively are estimated, implying that about 53% of solar radiation at the top of the atmosphere reaches the study area after attenuation. The satellite data has a total monthly mean horizontal Global Solar irradiance of 366.62 MJm −2 day −1 . The study shows that the region is a potential field to harness and optimize solar energy for the operation of photovoltaic systems and solar collectors for industrial and domestic applications.