Deep analysis of soiling effect on glass transmittance of PV modules in seven sites in Morocco

Abstract This study is based on the characterization of soiling on glass samples exposed under real conditions at seven sites in the region of Rabat-Sale-Kenitra in Morocco. The obtained results show that soiling is a much localized phenomenon. Indeed, the deposition densities in this study were observed in the range of 0.37 g/m2/month and 2.86 g/m2/month. The effect of soiling on glass transmittance showed a reduction in the range of 1.05%/month and 10.04%/month. These rates depend on the tilt angle as well as on the exposure period in the year. It has also been noticed that there is a positive and linear correlation between the mass density of the deposit and the loss of transmittance. This depends on the period and location of exposure. However, the type of dust may affect the degree of transmittance reduction. Morphological analysis has shown that the particle size distribution has been found prevailing in the range 3–14 μm. Although some particles have irregular shapes, the majority of dust particles have a rather regular shape. In addition, the cementation at the samples located in the nearest place to the ocean is observed enhanced by the presence of salt crystals on the surface.