Assessment of solar radiation variability and its impact on estimated photovoltaic electricity output over Kano, Nigeria

Abstract

This study assessed the variability of solar radiation and its impact on photovoltaic (PV) energy generation in Kano, a Sahelian city in Nigeria located at latitude 12.05^oN and longitude 8.20^oE. Thirty-one years (1990-2020) of meteorological data obtained from the Nigerian Meteorological Agency (NiMet) were used. Monthly, seasonal, and annual variations in global solar radiation (GSR), sunshine duration, and mean temperature were analysed to evaluate their influence on solar-energy output. The average annual GSR was 17.86 MJ m^-2 day^-1, the mean sunshine duration was 7.55 h day^-1, and the mean annual temperature was 26.78^oC. Using a 21.9%-efficient monocrystalline panel with an area of 2.58 m², the estimated mean monthly energy output was 2721.44 kWh, with peak generation occurring during the rainy season. Correlation analysis showed a strong positive relationship between GSR and energy output. Among the empirical models tested, Garcia's temperature-based model performed best, with R² = 92.2%. The findings confirm that solar-radiation variability significantly influences PV generation and that temperature-based models provide superior estimation accuracy in Sahelian climates, supporting large-scale solar deployment in northern Nigeria.