Investigation on an underwater solar concentrating photovoltaic-membrane distillation (CPV-MD) integrated system

This paper presents an underwater solar concentrating photovoltaic-membrane distillation (CPV-MD) integrated system for regions of coastal cities and islands where land resources are insufficient and suffer from critical shortages in electricity and freshwater. A deformable solar concentrator that works underwater is innovatively designed and matched with the photovoltaic-membrane distillation module. Given its application scenario, the integrated system is designed without metallic components to prevent seawater corrosion. The concentrator's optical characteristics are revealed via optical simulations. The results illustrate that the concentrator bears optimal optical performance when its elastic membrane's deformation ratio α is 0.25 and height ratio γ is 0.35. An experimental setup with a solar cell radius of 50 mm is developed and tested in actual weather to reveal its electricity and freshwater yield performance. It is found that the integrated system exhibits similar performance under the light incident angle of 0°and 10°. Additionally, for the experiment with average solar radiation of 514 W/m², the integrated system's output power varies between 1.53 W and 1.0 W, with an average electrical efficiency of 3.16 %. The accumulated freshwater yield is 67.8 g, with an average water yield efficiency of 28.5 %. This work may provide a new perspective on underwater solar energy utilization.