D. O. Akpootu and N. N. Gana
The solar constant is an important value for the studies of global energy balance and climate. The analysis of satellite data suggests a solar constant of 1366.10 with a measurement uncertainty of ±3 of the radiant energy emitted from the Sun. In this study, we used locally fabricated low cost devices of Aluminium cylinder to evaluate the solar constant and obtained an average value of 1381.26 from ground-based measurement of solar radiation, which turns out to be in close agreement with that suggested by satellite data measurement and those reported in many literatures. The observed slight deviation in our evaluated value is attributed to the fact that solar constant is not perfectly constant, but varies in relation to the solar activities and fluctuation in extraterrestrial radiation which is about 6.9 % during the year (from 1412.0 in January to 1321.0 in July) due to the Earth’s varying distance from the Sun. The analysis further show that the coefficient of determination, R2 > 85% for all the experimental days.