Atmospheric-moisture-driven evaporative cooling and concurrent hydrovoltaic energy harvesting in photovoltaic panels

Moisture-driven hydrovoltaic devices (MHDs) are an emerging class of energy harvesters that convert ambient moisture gradients into electricity, offering notable potential for decentralized power supply in off-grid regions. However, their output performance is often limited by sluggish moisture sorption and evaporation kinetics. Herein, we developed a high-performance cellulose-based MHD that is capable of delivering a stable voltage of ~0.7 V and a power density of 20 mW m -2 for over 30 days under ambient conditions (40%-70% RH, ~20 ℃). To overcome the intrinsic power limitations, we constructed a hybrid energy harvesting system by coupling the MHD with a photovoltaic (PV) panel using an interfacial hydrogel cooling layer. This synergistic design enables the MHD to harness waste heat generated by the PV panel, boosting its power output by ~150%. At the same time, evaporative cooling lowers the PV panel temperature by up to 13.5 °C, increasing its power output by ~15%. The integrated system can directly power various electronic devices and support energy storage, paving the way for sustainable, self-powered Internet of Things networks and net-zero energy buildings through efficient utilization of ambient moisture and solar-induced thermal waste.