A Hygroscopic Composite Backplate Enabling Passive Cooling of Photovoltaic Panels

Cooling photovoltaics (PV) matters since elevated temperature reduces efficiency and lifetime, but it is a great challenge when simultaneously pursuing effective cooling, low material cost, and light extra components. We herein propose a composite backplate for the passive cooling of PV panels, which consists of hygroscopic hydrogels with an adsorption-evaporative cooling effect and protective membranes. Besides, instant tough bonding with conventional PV backsheet allows for the composite backplate ease of implementation. Consequently, the composite backplate demonstrates nondegrading cooling performance during multiday field tests. Compared to a normal PV panel with good ventilation conditions, the average temperature reduction of each day varies from 1.5 to 6.4 degrees C under different climate conditions, indicating the absolute energy yield would increase by 0.57% to 2.43% of the yield under 25 degrees C. Considering the nearly unchanged appearance, moderate weight increase, and low raw material costs, this composite backplate facilitates benefiting from cooling PV panels attainable.