Experimental outdoor evaluation of adaptive radiative cooling and a dew-relocating shutter for renewable-energy photovoltaic systems

Daytime radiative cooling can reduce photovoltaic (PV) operating temperatures but may intensify nocturnal overcooling, dew formation, and dust adhesion. This study experimentally evaluated a transparent polydimethylsiloxane (PDMS) radiative-cooling film integrated with an adaptive low-emissivity shutter under hot-arid outdoor conditions in Najran, Saudi Arabia. Eight 100-W monocrystalline PERC modules were investigated using a replicated 2 × 2 factorial design comprising bare (PV-B), film-only (PV-RC), shutter-only (PV-AS), and integrated (PV-AD) configurations. The PDMS film exhibited a solar-weighted transmittance of 0.914 and an atmospheric-window emissivity of 0.918, with a 2.09% optical power penalty. Film presence reduced the adjusted peak-period front-glass temperature by 4.24 °C, although the associated cooling gain did not fully offset optical attenuation under clean conditions. The optimized shutter configuration employed a 30-mm gap, a 1.55 °C activation threshold, and a 1.08 °C hysteresis width. Adaptive shielding reduced PV-surface Dew Exposure Index by 74.9%, wetness duration by 75.7%, and dew mass by 83.8%, primarily relocating condensation to the externally drained shutter surface. Shutter actuation required 0.40 Wh night −1 , with controller and sensor consumption accounted for separately. Despite a 0.33% clean-condition net-energy deficit, PV-AD achieved a day-45 soiling ratio of 0.955 compared with 0.896 for PV-B. Over the 45-day natural-soiling period, cumulative net energy increased from 21.00 to 21.59 kWh, representing a 2.81% improvement. These findings demonstrate that combining daytime radiative cooling with adaptive nighttime shielding can mitigate dew-assisted soiling and improve multi-week PV energy yield under the tested environmental conditions.