Experimental investigation on the condensation characteristics and self-cleaning law of hydrophilic/super-hydrophilic dusty surfaces of bifacial photovoltaic panels

Dust deposition can significantly reduce the conversion efficiency of bifacial photovoltaic modules. In order to solve this problem, the condensation characteristics of bifacial photovoltaic panels with hydrophilic and super-hydrophilic surfaces are studied. The kinetical models of condensation liquid and particles are established, and their dynamic interactions are analyzed. The self-cleaning mechanisms of hydrophilic and super-hydrophilic surfaces are revealed. The results indicate that condensate on hydrophilic surfaces primarily forms droplets condensation, with a small amount of film-like condensation. In contrast, super-hydrophilic surfaces exhibit only film-like condensation. The head of droplet condensation has a slight self-cleaning power. The increased thermal resistance caused by the film-like tail prolongs the condensation cycle, thereby inhibiting the self-cleaning process. When transmissivity drops to approximately 65 % after PV dust accumulation, dust particles reduce the hydrophilic surfaces condensation cycle by about 25 %. Under the condition of dust deposition at the photovoltaic site, the transmissivity recovery values for bifacial photovoltaic modules are below 6.21 % for hydrophilic surfaces and 2.00 % for super-hydrophilic surfaces, respectively. Super-hydrophilic surfaces exhibit inferior self-cleaning performance compared to hydrophilic surfaces. These results provide theoretical support for solving the problem of bifacial photovoltaic panels dust accumulation.