Self-recovering passive cooling utilizing endothermic reaction of NH 4 NO 3 /H 2 O driven by water sorption for photovoltaic cell

Power efficiency of photovoltaic cell is significantly affected by the cell temperature. Here, a self-recovering passive cooling unit is developed. The water-saturated zeolite 13X is coated on the back side of photovoltaic cell, and ammonium nitrate is dispersed as a layer to form a thin film. When heat is supplied, water is desorbed from zeolite 13X (latent cooling), and dissolves ammonium nitrate to induce endothermic reaction cooling. It is a reversible process that recovers itself at night. The unit works on the basis that the water sorption performance of porous materials is inversely proportional to temperature, and the solubility of endothermic reaction pairs increases proportionally with temperature. The average temperature of photovoltaic cell can be reduced by 15.1 °C, and the cooling energy density reaches 2,876 kJ/kg with average cooling power of 403 W/m 2 . We show that highly efficient passive cooling comprising inexpensive materials for photovoltaic cell could be achieved.