Study of Atmospheric Turbidity and Its Effect on Solar Energy Yield in Maiduguri, Borno State

Atmospheric turbidity, caused by aerosols including harmattan dust, smoke, and water vapour, attenuates direct solar radiation and reduces the energy output of solar photovoltaic and solar thermal systems. Maiduguri in Borno State, North East Nigeria, is subject to severe harmattan events during the November to February dry season that dramatically affect solar resource availability. This study assesses the Linke turbidity factor and Angstrom turbidity coefficient for Maiduguri using one year of direct normal irradiance and diffuse irradiance measurements from a rotating shadowband irradiometer. The measured turbidity values are correlated with aerosol optical depth data from the AERONET station at Banizoumbou, Niger, and MODIS satellite aerosol products. The energy output reduction of a 10 kWp crystalline silicon PV system is simulated using PVsyst software for measured turbidity conditions versus standard clear sky conditions. Results indicate Linke turbidity factors ranging from 2.1 in March to 6.8 in January, with harmattan events producing turbidity spikes exceeding 10. The energy yield penalty from turbidity under high-harmattan conditions reaches 22 percent reduction relative to clear sky output. The study recommends turbidity-adjusted energy yield calculations for solar project feasibility assessments in North East Nigeria. Keywords: atmospheric turbidity, harmattan, solar energy, Maiduguri, aerosol optical depth