A numerical study of the impacts of photovoltaic system on underneath water evaporation from a salt-production pond

Photovoltaic (PV) agriculture, a combination of photovoltaic power generation and agricultural activities, is attracting more and more attentions. In this study, novel photovoltaic system is designed to harvest photovoltaic electricity and evaporate sea water to harvest salt simultaneously. A three-dimensional (3-D) numerical model is established with solar radiation field, PV panels and an open-air water evaporation pond. The effects of PV panels with different installing heights and coverage area on the water evaporation are evaluated under windless and crosswind conditions. The results indicate the evaporation rate of water decreases with the installation of PV panels under windless condition, since the water vapor accumulation above water surface lowers the evaporation driven potential. However, with the favour of crosswind, the evaporation rate is enhanced as the vapor is blew away. Besides, the installing height of PV panels greatly impact the water evaporation rate. In specific, lower PV panels lead to lower water evaporation rates. But beyond a certain height, the PV panels no longer affects the evaporation rate, when the hydrodynamic boundary layers on both water surface and PV panels are not interfered. On the other hand, the PV panels prevent the water evaporation via the leeward vortex. The more vortices are generated, the more water vapor is reserved. Therefore, the water evaporation rate is decreased with the increasing coverage area of PV panels. This research provides insights of the effects of PV on water evaporation with wind disturbance, prompting design optimizations of photovoltaic-salt co-generation plants.