Dual-functional carbon fiber-hygroscopic hydrogel composites for mechanically robust and efficient photovoltaic cooling

Hydrogel-based passive cooling has demonstrated significant potential for addressing the heat dissipation issue in solar photovoltaic (PV) modules to enhance their power generation. However, existing hydrogel designs face a critical limitation: optimizing thermal conductivity often sacrifices mechanical durability, while mechanical reinforcement strategies neglect heat transfer enhancement. To address this trade-off, a dual-functional hydrogel composite was developed to provide efficient evaporative cooling by synergistically integrating carbon fiber fabrics (CFFs) with hygroscopic polyacrylamide (PAM) hydrogel and CaCl2. This composite uniquely achieves a 622 % enhancement in mechanical strength alongside significantly improved thermal performance, delivering an average evaporative cooling power of 203 W m−2. Under controlled laboratory conditions, the composite exhibited an average temperature reduction of 19 °C, with indoor experiments further revealing a peak temperature drop of 17.3 °C and 14.2 % average power enhancement. Additionally, A heat and mass transfer model was established to elucidate water vapor desorption dynamics, providing mechanistic insights into humidity- and temperature-dependent performance. Furthermore, field tests under diverse environments validated the composite's adaptability, achieving a maximum temperature reduction of 13.5 °C and 5.83 % average power improvement. These results, supported by both experimental and theoretical robustness, highlight the composite's potential as a scalable and energy-efficient solution for real-world photovoltaic thermal management.