Soiling mapping through optical losses for Nigeria

Soiling consists of the accumulation of dust on the solar panel's surface and has a deleterious effect on solar photovoltaic devices' performance, which varies with location. However, soiling losses and rates are significantly under-reported or underestimated since regional differences and seasonal variations are overlooked. Accurate prediction of PV soiling losses for a particular location can save revenue losses associated with a solar PV system. This research investigated the effect of soiling on PV performance through optical losses by employing a low-cost soiling station. Low iron glass coupons (5 mm × 5 mm) were exposed on three angles (vertical, tilt-45°, and horizontal) in seven sites across Nigeria to collect annual, seasonal and monthly soiling data. Each coupon was then subjected to optical characterisation using a spectrometer and imaging analysis using the SEM/EDX. The finding shows significant optical losses across the country, with all the highest rates recorded on coupons exposed on the horizontal plane, where the maximum loss of 88% was recorded on the Abuja, North Central (ABV) coupon. SEM/EDX finding illustrated minerals with the potential to affect light transmittance, and the pollutant data confirmed the particles. The optical results were further employed to map the soiling distribution across the country. A wide deviation was observed from the data on the Global Solar Atlas, as it disproportionately underestimated the soiling losses across the world.