Stanfords new solar panels work at night and there’s more to come

Solar panels are an excellent alternative to more traditional fossil fuel energy sources but today, even though in the future they will work when it’s cloudy, raining, snowing, and more, as well as be up to 132 percent energy efficient, they come with a massive caveat, they can only be used during the day. While we have lunar solar panel prototypes that can generate electricity at night thanks to the development of a new kind of nanophotonic material, Sid Assawaworrarit, an electrical engineer and PhD candidate at Stanford University, has taken a different approach to create a solar panel that works 24-7.

He and his colleagues have created a device that helps regular solar panels generate electricity using the fluctuating temperature of ambient air, something we’ve seen before but only as part of a futuristic battery pack system from MIT.

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As it turns out, solar panels can kind of work in reverse; solar panels emit infrared radiation even in the absence of light. This takes the form of protons carrying heat away from the solar panel via wavelengths invisible to the human eye. On a clear day, when there aren’t any clouds in the sky to reflect infrared light back toward Earth, this heat transfer creates a temperature difference of a few degrees, which is the secret sauce to Assaworrarit’s device.

The device, called a thermoelectric generator, which are also used in new wearables to generate electricity from our skin, catches the heat that flows between the warm air and the solar panel and turns it into energy. Assaworrarit’s team is currently able to obtain about 50 milliwatts per square meter of solar panel. Though this is a small fraction of the amount of electricity a solar panel can generate during the day, most are capable of about 150 watts per square meter, Assaworrarit says the right location and a few tweaks to the technology may allow the device to pick up “about one or two watts per square meter,” which is far more than solar panels were previously able to generate at night.

Assaworrarit’s team isn’t the first to use a thermoelectric generator to capture heat from the night, but their approach looks promising when it comes to using solar panels that already exist for daytime use. By using an aluminum plate to reduce the amount of heat that could escape from the edges of their solar panels, the team was able to multiply their technology’s generated energy nearly ten times.

Night-effective solar panels carry a significant amount of potential. Scientists who use solar-powered equipment, like meteorologists and wildlife researchers or anti-poaching rangers, could benefit from more reliable power sources and lighter backup battery loads. And those who rely on solar power and other off-grid solutions for daily life, which amounts to over one billion people globally, could also benefit from panels capable of providing a more consistent stream of electricity.