In a study published in Applied Physics Letters, researchers from Stanford University have introduced a photovoltaic cell capable of harvesting solar energy both during the day and at night, eliminating the need for battery storage. The device leverages the Earth’s heat radiation back into space, a process that occurs on a scale comparable to the solar radiation received.

Solar cells, or photovoltaic panels, typically generate energy during the day, but storing this energy for later use requires substantial storage capacity. At night, these solar cells radiate and lose heat to the atmosphere, dropping to temperatures a few degrees below ambient.

The new device under development utilizes a thermoelectric module to generate voltage and current from the temperature difference between the solar cell and the air. This process relies on the thermal design of the system, which features a hot side and a cold side.

Solar Power Station in Space: A Solution to the Energy Crisis? In this setup, “the thermoelectric needs to have very good contact with both the cold side, which is the solar cell, and the hot side, which is the ambient air,” explained Sid Assawaworrarit, the study’s lead author. “Without this, it wouldn’t be possible to generate much energy from this mechanism.”

A New Way to Generate Energy The installation is cost-effective and, in principle, could be integrated into existing solar cells. It is also straightforward to construct, making it feasible to deploy in remote areas with limited resources.

“We managed to build everything from off-the-shelf components, ensuring very good thermal contact, and the most expensive part of the whole setup was the thermoelectric itself,” noted Zunaid Omair, one of the study’s authors.

Generating electricity for nighttime lighting requires a few watts of power. The current device generates 50 milliwatts per square meter, meaning that lighting would require about 20 square meters of photovoltaic area.

“None of these components were specifically designed for this purpose,” said Shanhui Fan, another author of the study. “So, I believe there is room for improvement, in the sense that if each of these components were specifically designed for our purpose, I think the performance could be better.”

This new solar cell offers a low-cost installation option, as it can be incorporated into existing photovoltaic panels and is capable of producing energy for use at night. The team aims to optimize the device’s thermal insulation and thermoelectric components. They are also exploring engineering enhancements to the solar cell itself to improve radiative cooling performance without affecting its solar energy collection capability.