An investigation on surface dust removal via continuous droplets impacting for PV application

Abstract

Solar energy offers a promising and sustainable alternative to traditional energy. However, surface soiling can reduce the efficiency of PV panels dramatically. In this paper, we investigate the continuous droplets impacting on dusty surfaces to achieve surface cleaning. The effects of surface wettability, dust types, water volume, and surfactants on the dynamic behavior and macroscopic efficacy of droplet dust removal are analyzed. For distilled water, the superhydrophilic surface achieves the best dust removal with transmittance recovering to 96 % of a clean surface, while the hydrophilic surface is worst. Notable water channels are observed on the hydrophilic surface, which results in a significant contrast in surface transmittance between the interior and exterior of these channels, 90 % and 73 %, respectively. The overall dust-removal performance on the surface is rather poor, and a large amount of water resources are wasted. Interestingly, surfactants solution can disrupt the water channels on the hydrophilic surface relying on sequential sliding and bouncing, thus enhancing the dust removal efficiency. It is found that anionic surfactant (AS) solution demonstrates the optimal performance. The relative dust removal mass is just 48 % using 5 ml water, while it increases to 84 % for AS0.5. This is attributed to the repulsive forces between the negatively charged dust and molecules of anionic surfactant. This finding helps to the self-cleaning applications of water droplet impacting for PV modules.