Integration of radiative sky cooling to the photovoltaic and thermoelectric system for improved space cooling

Abstract The feasibility of integrating the radiative sky cooling ability of common photovoltaic cells into the photovoltaic-thermoelectric cooler to further enhance the space cooling energy density is analyzed in this paper. Specifically, daytime cooling is obtained by the photovoltaic panel powering the thermoelectric cooler while the same photovoltaic panel provides nighttime radiative sky cooling. To achieve an optimal temporal match between the new method’s output cooling power to a cooling building’s time-varying cooling load (with 4 occupants and 24 m2 floor space), two thermoelectric cooler modes of operation are studied; The first continuously operates the thermoelectric cooler power at the time-averaged value while the second directly supplies the photovoltaic power to the thermoelectric cooler in the daytime. Furthermore, a spectral model is used to accurately estimate the radiative energy of crystalline solar cells based on their emissivity spectrum. It is found that radiative sky cooling can almost double the equivalent solar to cooling coefficient of performance over the basic photovoltaic and thermoelectric cooler system (from 0.1099 to 0.2054). The photovoltaic area only needed to be 12–17 m2, and the second operating mode can better match the supply versus cooling demand ratio while yielding a relatively consistent 10 °C difference throughout the entire day.