Global pictures of our planet at night are one of the greatest indicators not just of population distributions but also of infrastructure distributions. There are myriad places – even here in the U.S. – where people live in remote locations that aren’t wired into the power grid. For these folks, life doesn’t have to be low tech, but sometimes it does end up being rather diurnal.

Solar panels have become a reliable and more or less affordable way for anyone to get power, at least while the Sun is up. Unfortunately, batteries and all the associated hardware that are needed to store electricity are still costly, bulky, and less affordable. This means that for some, with the setting Sun, everything powers down until morning.

Part of this problem can be mitigated if other means of energy generation can be found, and the solar panels themselves may just be one possible alternative source.

During daylight, solar panels heat up as they are only able to transform some of the solar energy into power. A perfectly effective solar panel would be at the same temperature as the surrounding air. During the night, that heat energy radiates away and is lost in the surrounding air. In a new paper in Applied Physics Letters, researchers describe a new photoelectric cell that harvests heat energy, both from the solar panels and the surrounding air. This can generate around-the-clock power and turn what would otherwise be waste heat into new energy. This work was led by Sid Assawaworrarit.

According to project researcher Zunaid Omair: What we managed to do here is build the whole thing from off-the-shelf components, have a very good thermal contact, and the most expensive thing in the whole setup was the thermoelectric itself.

Fellow researcher Shanhui Fan adds: None of these components were specifically engineered for this purpose. So, I think there’s room for improvement, in the sense that, if one really engineered each of these components for our purpose, I think the performance could be better.

Here is to hoping that this tech can be commercialized in the not too distant future, and we can start to power the world around the clock without needing more batteries.

We’re changing our world. That can no longer be denied. But we may be able to tech our way into changing it less as we move forward.

More Information

Solar cell keeps working long after sun sets (EurekAlert)

“Nighttime electric power generation at a density of 50 mW/m2 via radiative cooling of a photovoltaic cell,”  Sid Assawaworrarit,  Zunaid Omair, and  Shanhui Fan, 2022 April 5, Applied Physics Letters