Research on passive cooling of photovoltaics based on heat dissipation fins combined with hydrogel

Hydrogel-based cooling for photovoltaic modules has emerged as a research hotspot in recent years. However, the intrinsically low thermal conductivity of hydrogels poses a negative effect on overall heat dissipation performance. This study proposes a strategy that replaces costly nanomaterial dopants in hydrogels with heat-dissipating fins. The gaps between the fins are partially filled with a thermoresponsive hydrogel, poly-N-isopropyl acrylamide, which has a Lower Critical Solution Temperature of 32.2 °C. This design both substantially increases the heat-exchange contact area between the photovoltaic and the hydrogel and, by coupling the fins’ convective heat transfer with the hydrogel’s phase-change evaporative cooling (latent heat of vaporization ≈ 2440 kJ·kg − 1), achieves a synergistic enhancement of convective and evaporative heat removal, thereby significantly improving overall heat-transfer efficiency. Comparative experiments show that, under low wind-speed conditions, the photovoltaic–fin–poly-N-isopropyl-acrylamide structure reduces the photovoltaic average temperature by 19.6 °C relative to the bare photovoltaic control and increases the absolute cell efficiency by 1.3 %. Outdoor experiments have demonstrated that the cooling duration of the proposed structure can reach up to 9 h, and the PNIPAM hydrogel exhibits excellent swelling performance, indicating its great potential for adsorption–evaporation applications in diurnal cycles, particularly under high nighttime humidity conditions. This finding has important implications for research on photovoltaic thermal management.