Effect of abrasive cleaning loads on the durability of hydrophobic anti-soiling coating

The durability of anti-soiling coatings (ASC) on photovoltaic (PV) modules is critical for mitigating soiling-induced energy losses and reducing cleaning frequency, particularly in regions with high soiling rates. This study experimentally evaluates the impact of four cleaning loads (300 gf, 600 gf, 900 gf, and 1010 gf) on hydrophobic ASC durability using glass coupons in a controlled indoor environment. To replicate realistic field conditions, a dew-dust-dry-clean (DDDC) test sequence was employed, simulating daily temperature, humidity and soiling variations observed in actual PV installations. To assess cleaning efficacy, the indoor experiment was conducted for two artificial dust gravimetric densities (0.2 and 0.6 mg/cm²). The findings reveal that ASC durability is not linearly dependent on the applied load but varies based on the interaction between the brush bristles and the glass surface. ASC subjected to lower loads exhibited extended durability, while moderate loads accelerated degradation due to increased bristle contact. Interestingly, the highest load showed improved durability compared to moderate loads. The number of cleaning cycles required for complete soiling removal decreases with increasing loads. For identical cleaning efficacy, the durability of the coating is marginally worse for the highest load than for the smallest load, while the coating degraded the fastest for moderate loads. These results provide critical insights for optimizing cleaning strategies to balance coating durability and cleaning efficacy, ensuring the long-term performance and cost-effectiveness of anti-soiling and anti-reflective coatings.