Correlation between laboratory and outdoor soiling experiments with anti-soiling coatings

Dust deposition on PV module surfaces is a complex issue influenced by various factors such as weather conditions, dust composition, and surface properties. Outdoor soiling experiments experience fluctuations in environmental conditions, leading to natural inconsistencies and difficulties in reproducibility. On the other hand, laboratory experiments can be conducted in a well-controlled environment and provide rapid results. This study aims to analyze and correlate outdoor and indoor soiling experiments using different anti-soiling coated glass samples. The outdoor experiments, conducted over a year at eight locations in Saudi Arabia, revealed significant variations in soiling behaviour. These were evaluated by assessing light transmission loss through optical transmission analysis. Indoor experiments were conducted in a controlled soiling test chamber and analyzed by optical microscopy to replicate the outdoor behaviour observed with different coating types. Dry laboratory tests followed by wind blow tests showed a strong correlation (Average Pearson r = 0.65) with outdoor soiling results for most locations. In contrast, heavy dew tests showed an anti-correlation with the outdoor soiling results. Therefore, it was also concluded that the resuspension is the primary removal mechanism affecting the performance of the Anti-Soiling Coatings (ASCs) in the dry environments.