Influence mechanism of liquid bridge evaporation on the dynamic behaviour of dust particles on solar photovoltaic panels

Solar photovoltaics (PVs) are one of the most promising renewable energy sources to solve the global environmental and energy crises. Dust agglomeration on PV panels greatly affects their operation life and power generation efficiency. In this study, the evaporation mechanism and laws of liquid bridges as well as the evaporation time and interaction forces for liquid bridges and particles are investigated. The effects of liquid bridge evaporation and its influencing factors on dust dynamic behaviour are discussed. Liquid bridge evaporation in the muddy state with small particle spacing can cause particle agglomeration on PV panels. However, it is very difficult for the capillary, the ribbon, and the pendulum states or the muddy state with large particle spacing to affect particle motion. In the muddy state, the interaction force for a small particle spacing consists of not only the liquid bridge force but also the drag force caused by liquid bridge evaporation, and that for a large particle spacing consists of only the drag force; in the other three states, the interaction force consists of only the liquid bridge force. Liquid bridge evaporation can greatly intensify particle agglomeration and even scaling processes with decreasing particle size. These findings can provide important theoretical guidance and value for engineering improvements in power generation and safe operation of PV panels.