Assessment of the Impact of Harmattan Dust on Solar Panel Soiling Losses in North West Nigerian Solar Installations

Harmattan dust deposition on solar photovoltaic panel surfaces causes optical soiling losses that reduce electrical output and reduce the return on investment of solar energy installations in northern Nigeria. This study assesses the magnitude and characteristics of soiling losses on photovoltaic panels at three solar installations in Katsina, Zamfara, and Sokoto States, North West Nigeria, over a complete dry season harmattan period from November to March. A matched pair experimental design was used, with soiled and periodically cleaned reference panels installed side by side at each site to isolate soiling effects. Daily energy output, current-voltage characteristic curves, and panel transmittance measurements were used to quantify soiling loss factors. Simultaneously, dust deposition rates were measured using passive deposition gauges calibrated against gravimetric PM10 samplers. Results indicate cumulative soiling losses reaching 23 to 35 percent of daily energy output after 30 days without cleaning, with the highest rates at the Sokoto site where dust deposition rates averaged 4.2 g/m2/day during peak harmattan. Statistical analysis establishes a linear relationship between cumulative deposition mass and soiling loss ratio applicable for predictive modeling of cleaning schedules. The study develops a cleaning frequency optimization model that minimizes the ratio of energy loss from soiling to water and labor costs of cleaning. Recommendations on optimal cleaning intervals, water-efficient cleaning methods, and anti-soiling coating technologies relevant to North West Nigeria are provided. Keywords: solar panel soiling, harmattan dust, photovoltaic, North West Nigeria, cleaning optimization