Abstract
Solar energy devices such as solar photovoltaic (PV) panels and solar air heaters (SAHs) suffer from reduced efficiency, thermal stress, and permanent damage when they overheat. Cooling such devices while simultaneously maintaining the maximum absorption of solar light waves remains a significant challenge. A copper substrate was coated with graphene oxide (rGO) and silver nanowires (AgNWs) to augment radiative heat absorption on one side and convective cooling on the other side. The rGO/AgNW surface on both sides enhanced both solar heat wave absorption via the textured surface, as in a blackbody in a cavity, and convective cooling via the increased total surface area. For natural convection, fresh cooling air was supplied via buoyancy. For duct flow in a confined channel, the inner surface of the duct was coated with rGO/AgNW to promote convective cooling. This arrangement simulated actual air cooling of a solar PV panel or SAH. The incoming air into the duct was heated by the high temperature wall. In return, the wall temperature of the duct cooled, which in turn prevented overheating and provided long-term stability for the solar PV panel or SAH. Furthermore, the removed heat can be used to power thermoelectric devices or for domestic and industrial applications.