Availability of Direct Solar Radiation in Uganda
Abstract
Investigation on the potential applications of concentrating solar energy systems and selection of optimum sites requires information on the geographical distribution of direct normal solar irradiance over an area of interest. Direct solar radiation data is best provided by measurements, but due to high cost of the pyreheliometers, many developing countries are without this instrument. The most common solar radiation parameter available at most Meteorological stations in Uganda is the sunshine duration measured mainly with the Campbell-Stokes sunshine recorder. The CSD1 Sunshine Duration sensors are used in a few places in Uganda. Using solar radiation models, we developed an hourly direct solar radiation distribution for Uganda from measured data of daily sunshine duration and daily global and diffuse solar radiation available. Comparison between the model and measured direct hourly solar radiation gave a MBE and RMSE of -0.112 and 0.22 kW/m2 respectively. Hourly direct normal solar radiation intensities of the order of 500 W/m2 can be expected as early as 0900 hours and as late as 1600 hours for locations in the eastern and northern regions of Uganda. This is between October and March. The intensities of direct solar irradiance are higher in eastern and northern regions