Efficient Passive Cooling for Photovoltaic Cells via Self-Hygroscopic Polyvinyl Alcohol/Graphene Films

Photovoltaic (PV) technology plays a pivotal role in energy transformation processes, especially for sustainable energy systems. However, the conversion efficiency of the PV cells is adversely affected by increasing temperature, leading to a reduction in their overall performance. In this study, a self-hygroscopic polyvinyl alcohol/graphene (SPG) cooling film, comprising a graphene layer and a polyvinyl alcohol (PVA) hydrogel layer with lithium bromide (LiBr), is introduced to passively reduce the working temperature of the PV cells. The graphene layer, as a heat-conducting layer, can efficiently conduct heat from the heat source to the self-hygroscopic PVA hydrogel layer used as an evaporation cooling layer. In addition, the introduction of LiBr endows the PVA hydrogel with an excellent self-hygroscopic property. The SPG cooling film demonstrates an outstanding cooling performance under the synergistic effect of the graphene film and the self-hygroscopic PVA hydrogel. In the outdoor experiments, the SPG cooling film can reduce the temperature of the PV cells by 20.6°C and increase its average output power from 74 to 93 W/m², about a 25.7% increase. This cooling film demonstrates significant potential for enhancing cooling performance in electronic devices and could be widely used in the thermal management of PV cells.