Comparative Analysis of Site-Specific Soiling Losses on PV Power Production

The rapid global expansion of utility-scale solar power parks has led to an increased effort to overcome the challenges related to accumulated soiling on PV panels. So far, little attention has been paid to the differing impacts of various dust types. This article focuses on the decreased transmission of sunlight through the PV cover glass with an increased level of dust layer density. The loss in the PV power production due to soiling is heavily dependent on site-specific climatological and anthropological parameters, such as topography, weather, human activity, and PV module type. Three natural dust samples from solar power plants in Egypt and Jordan were analyzed for structural, chemical, and optical attributes, including transmission measurements. Cement was added to the analysis and compared with the natural dust samples. We show that different reductions in transmission between the different dust types are mostly ascribed to a dissimilar particle size distribution and albedo, where the former is the most crucial determinant. Under equal weather conditions and similar dust layer density on the PV cover glass plates, a lower particle size distribution would result in a more dramatic drop of transmission. Additionally, the darker appearance of the grains increases the absorption of sunlight causing a further loss of light due to soiling. The results show that between the "best" and the "worst" natural panel dust studied in this article, a difference in transmission of 5 % was identified. At equal weather conditions, this directly translates into a similar loss in electricity production.