Volume 60

Synergistic Passive Cooling of Photovoltaics: A Numerical Study on CombiningRadiative Cooling and Hydrogel-based Evaporative Cooling Weijian Lin, Tao Li, Tao Ma

Abstract

Evaporative cooling using hygroscopic compositehydrogels and radiative cooling are widely studiedpassive thermal management strategies for photovoltaic(PV) modules. This work explores a synergistic approachthat integrates evaporative cooling through ahygroscopic hydrogel on the back side with radiativecooling on the front side of PV modules. A highlyaccurate heat and mass transfer model is developed andvalidated to simulate three configurations: radiativecooling only; evaporative cooling only on the back side;and the combined use of both techniques. Resultsdemonstrate that the hybrid configuration achieves thebest cooling performance, yielding an averagetemperature reduction of 3.2 °C and power generationefficiency (PCE) increase by 1.2%, which corresponds toa 500% and 26% relative improvement in PCE comparedto the radiative-cooling-only and evaporative-cooling-only cases, respectively. Notably, radiative cooling hasonly a minor influence on the hydrogel’s absorption anddesorption dynamics, increasing nighttime waterabsorption by about 1%, while the enhanced radiationextends the duration of the positive temperaturereduction effect by 10%. Radiative cooling can beconsidered as a supplementary method coupled with PVmodules, where evaporative cooling serves as theprimary passive cooling mechanism.

Keywords PV passive thermal management,evaporative cooling, radiative cooling, synergisticstrategy