An Assessment of the Variations of Solar Irradiance with Temperature and Relative Humidity of Abuja During the Rainy Season
DOI:
https://doi.org/10.33003/fjorae.2026.0302.92Keywords:
Solar irradiance, Temperature, Relative humidity, Rainy season, Abuja, NigeriaAbstract
This study assessed the variation of solar irradiance in relation to atmospheric temperature and relative humidity in Abuja, Nigeria, during the rainy season from April to July 2026. Primary experimental data on solar irradiance, temperature and relative humidity were collected at 30-minute intervals using a digital pyranometer and automatic weather station. The collected data were analysed using daily and monthly averages, correlation analysis and multiple linear regression. The results showed considerable daily variation in solar irradiance, with observed values ranging approximately from 200 to 960 W/m². April recorded the highest individual irradiance value, while July generally exhibited the lowest overall irradiance conditions. Correlation analysis showed a positive relationship between temperature and solar irradiance, with the strongest association occurring in June (r = 0.7957). Relative humidity exhibited an inverse relationship with irradiance, with the strongest negative correlation also occurring in June (r = −0.8091). Multiple regression analysis indicated that temperature and relative humidity were jointly and significantly associated with solar irradiance, F(2, 73) = 10.753, p < 0.001. Temperature had a positive regression coefficient of 23.741 W/m² per °C, while relative humidity had a negative coefficient of −7.343 W/m² per percentage point. The model explained 22.52% of the variation in solar irradiance, indicating that substantial variability remained unexplained by the two predictors. The study concludes that temperature and relative humidity are significant atmospheric variables associated with solar-irradiance variability in Abuja during the rainy season, while other factors such as cloud cover, rainfall, atmospheric pressure and aerosol concentration may also contribute substantially to observed variations. The findings provide recent location-specific evidence that can support improved solar-resource assessment and photovoltaic planning in Abuja.
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