Comparative Analysis of Solar Energy Potential in Urban and Rural Areas of Nasarawa State

Nasarawa State, located within Nigeria's North Central geo-political zone and the Guinea savannah agro-ecological belt, receives a substantial annual solar resource, yet the extent to which this resource differs between the State's urban and rural areas has remained empirically under examined, despite its evident relevance for decentralized rural electrification and urban grid supplementation planning. This study empirically compared the solar energy potential of urban and rural areas of Nasarawa State using in-situ measurement of global solar radiation, sunshine duration, and ambient temperature over a twelve-month period. A comparative quantitative research design was adopted, with digital pyranometers and Campbell-Stokes sunshine recorders installed at three purposively identified urban stations (Lafia, Keffi, and Akwanga) and three rural stations (Awe, Obi, and Wamba) across Nasarawa State. To assess the broader national applicability of the measurement approach, an illustrative cross-validation exercise was additionally conducted using portable solarimeters deployed at one polytechnic randomly selected from each of Nigeria's six geo-political zones. Data were analysed using mean, standard deviation, independent-samples t-test, and two-way analysis of variance (ANOVA), at the 0.05 level of significance. Results showed that rural stations recorded a significantly higher mean daily global solar radiation (5.94 kWh/m²/day) than urban stations (5.41 kWh/m²/day), t(358) = 9.87, p < .05, a difference attributed principally to greater atmospheric aerosol loading and particulate air pollution associated with urban vehicular and industrial activity. Rural stations also recorded significantly longer mean daily sunshine duration than urban stations, t(358) = 7.42, p < .05. A significant interaction effect of location type (urban/rural) and season (dry/wet) on solar radiation was found, F(1,356) = 6.15, p < .05, with the urban-rural gap widening during the dry (harmattan) season. The study concludes that rural areas of Nasarawa State possess measurably higher solar energy potential than urban areas, and recommends prioritization of rural areas for off-grid solar electrification while urban areas would benefit from targeted air-quality management to enhance solar resource availability.