Assessing the Impact of Soiling, Tilt Angle, and Solar Radiation on the Performance of Solar PV Systems

Samuel Chukwujindu Nwokolo, Anthony Umunnakwe Obiwulu, Solomon Okechukwu Amadi, Julie C Ogbulezie


This research examined the observed datasets and a theoretically derived model for estimating yearly optimum tilt angle (β), maximum incident solar radiation (Hmax), clean gain indicator (CGI), and soiling loss indicator (SLI) at Mumbwa, Zambia, the Mediterranean Region, and low latitude locations across the globe. The cleaned tilted collector emerged as the best performing collector due to Hmax and much higher energy gains compared with the soiled collector. CGI showed an appreciable performance of 0.4737% over -0.4708% on the SLI, indicating that soiling on the surface of photovoltaic (PV) modules significantly depreciates the overall performance of PV modules. Two established empirical models obtained from the literature were compared with the established theoretical model (β=φ). The result revealed that the two models overestimated the observed annual optimum tilt angle in this paper, simply because the models were developed with high latitude location datasets from the Asia continent. However, the newly established monthly and yearly global radiation indicator (GRI) models by the authors in their previous paper performed excellently in the selected representative cities in the Mediterranean region.

Citation: Nwokolo, S., Obiwulu, A., Amadi, S., & Ogbulezie, J. (2023). Assessing the Impact of Soiling, Tilt Angle, and Solar Radiation on the Performance of Solar PV Systems. Trends in Renewable Energy, 9(2), 120-136. doi:


Global tilted irradiance; global horizontal irradiance; soiling; optimum tilt angle; maximum incident solar radiation

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