Researchers from the University of California, Davis explain in a recent paper, published in the journal ACS Photonics, that if you want to create a solar panel that generates electricity at night, you have to create one that operates the exact opposite way solar panels work during the day.

It’s referred to as the “anti-solar panel.”

Solar panels are cold compared to the Sun, so they absorb the Sun’s light and turn it into energy. Space is very cold, so if you point a panel on Earth that is comparatively warm toward it, it will radiate heat as invisible infrared light. This allows you to generate electricity by capturing that power. The paper claims such a device could generate about a quarter of the electricity at night that a normal solar panel generates during the day.

Read more: Anti-solar panel can generate electricity at night, researchers say