A solar energy harvesting system that performs two functions simultaneously has been developed by Pennsylvania State University researchers. The dual cooling and power strategy harnesses solar energy in a solar cell and directs heat away from structures through radiative cooling.

Working principle of the setup (left) and schematic of the cross-sectional view (right). Source: Cell Reports Physical Science, 2024; 101876

This type of cooling sends infrared light directly into outer space instantaneously without warming the surrounding air. As the surface of an object absorbs less radiation from the atmosphere but emits more, heat is lost, and cooling is achieved without the need for an external power source.

The system described in Cell Reports Physical Science consists of a transparent low-iron glass radiative cooler that is able to transmit 91% of sunlight, a visibly transparent infrared-opaque layer, and a 125 mm × 125 mm interdigitated back-contact photovoltaic cell. The radiative cooler component has no direct radiative heat exchange with the photovoltaic device. Under daylight conditions sunlight passes through the transparent radiative cooler and is absorbed by the solar cell positioned beneath to generate electricity.

Outdoor tests demonstrated that the dual system could surpass the electricity saving of a bare solar cell by as much as 30%. The radiative cooler reached 5.1° C below the ambient temperature under about 1,000 W/m² sunlight while the photovoltaic cell produces 159.9 W/m² simultaneously and from the same area.