Evaluating the distribution of soil particle size on glass samples by a new generation of optical microscopy for solar PV applications

Abstract

In this work, an image analysis technique combining a new generation optical microscope (Leica DM6 M) and Cleanliness Expert image acquisition and processing software is proposed for the study of dirt particles on PV modules in three different regions: Souss-Massa region, Drâa-Tafilalet region, and Rabat-Salé-Kénitra region. This method offers the possibility of providing an appropriate assessment of the particle size distribution. The analyzed glass samples were installed in these three different regions, on wooden holders tiled 15°, 30°, and 45° and for a period ranging from 64 to 75 days. The studies carried out to evaluate the soiling phenomenon based on image processing are very limited and do not take into account the total scanning of the analyzed surface. They are generally limited to a single (one) or a few images taken at different locations of the sample and are then extrapolated over the entire surface. This observation raises the question of the representativeness of the results obtained with respect to the result on the entire surface of the sample. In this context, we thought of carrying out this experimental study, which aims to answer this question and evaluate the particle size of the dirt samples on the PV modules. The results obtained in this study have shown that three images will be enough to represent the whole area of the sample. In addition, the dominant particle diameters by number are in the range of 1-5 µm.

Keywords: Correlation; Density of deposits; Drâa-Tafilalet; Leica Optic Microscope; Rabat-Sale-Kenitra; Soiling; Solar energy; Souss-Massa; Transmittance.