The knowledge of the amount of solar radiation in an area/region is very essential in the field of Solar Energy Physics. In this work two equations are put forward for estimating global solar radiation from common climate variables in data sparse regions. The first is the Hargreaves equation, R-s = 0.16R(a)T(d)(0.5) where R-a is the extraterrestrial solar radiation and T-d is the temperature difference (maximum minus minimum), while the second is the Angstrom equation, R-s = R-a(0.28 + 0.39n/N) where n and N are the measured sunshine hours and the maximum daylight duration respectively. The global solar radiation estimated by the two equations for three sites, Owerri (5 degrees 28'N, 7 degrees 2'E), Umudike (5 degrees 29'N, 7 degrees 33'E) and Ilorin (8 degrees 32'N, 4 degrees 46'E), located in different climate zones of in Nigeria, West Africa, are in agreement with those of earlier workers and that from Photovoltaic Geographic Information System (PVGIS) project. The implication of this in solar photovoltaic applications has been stressed. (C) 2007 Elsevier Ltd. All rights reserved.