Self-cleaning mechanisms and laws of hydrophilic or hydrophobic surfaces of solar photovoltaic glass

Abstract

Dust accumulation on solar photovoltaic (PV) glass greatly reduces its efficiency of power generation and service life. Traditional methods for cleaning PV glass generally exhibit serious shortcomings, such as excessive water consumption, high cost and low cleaning efficiency. Hydrophobic and hydrophilic surfaces have excellent self-cleaning characteristics and good mechanical properties, and their use for PV glass is expected to lead to efficient self-cleaning. In this study, extensive experimental and theoretical studies were conducted on the self-cleaning characteristics and dynamic behaviours of particles and droplets on both hydrophilic and hydrophobic surfaces. The effects of the condition of PV glass and the properties of particles and liquid droplets on self-cleaning by these two types of surfaces were studied. Furthermore, the self-cleaning mechanisms for hydrophilic and hydrophobic surfaces were compared. The results indicated that the hydrophobic and hydrophilic surfaces underwent self-cleaning in five and three stages, respectively, under the coupled effects of gravitational, gasliquid interfacial, adhesive and frictional forces. The cleaning time of hydrophilic and hydrophobic surfaces increased by approximately 141% and decreased by approximately 73%, respectively, when the contact angle increased by 60°. The self-cleaning abilities of hydrophilic and hydrophobic surfaces were improved by increasing the liquid droplet volume, surface tension or installation angles and decreasing the particle masses.