Experimental investigation of the anti-soiling performances of different wettability of transparent coatings: Superhydrophilic, hydrophilic, hydrophobic and superhydrophobic coatings

Abstract

Natural soiling of photovoltaic (PV) panel is an increasing problem especially in arid and desert areas. Finding a strategy that can reduce dust adhesion on PV panels is highly desirable but remains challenging. In this paper, different wettability of transparent coatings including superhydrophilic, hydrophilic, hydrophobic and superhydrophobic coatings were prepared to investigate the importance of surface roughness and surface energy. Their anti-soiling effects were investigated under different airflow velocity and different tilt angles. Dust deposition density, reduced transmittance, the ratio of reduced transmittance between bare glass surfaces and coatings, and PV efficiency reduction were used to characterize dust resistance performances. It is found that dust adhesion on superhydrophilic coatings was eminently governed by their respective high surface energy, with surface roughness rendering lesser contribution towards resisting/adhering effects. However, for other three coatings, further reducing the surface energy had little influence on the improvement of dust-proof ability. A large airflow velocity is beneficial to resist dust adhesion for all four types of coatings. However, a large airflow velocity has a limited ability to improve the anti-soiling effect of superhydrophilic coating under different tilt angles compared with other three coatings. The anti-soiling coatings can be referred to hydrophilic and hydrophobic coatings, not limited to superhydrophobic coating only. The study provides an invaluable guiding significance for preparation of dust-resistant coatings.