Researchers in California are working on solar panel prototypes that will keep making power in the dark.

In a new paper published in the journal ACS Photonics, researchers from the University of California, Davis (UC Davis) detail how they built what they are calling an “anti-solar panel.” This new type of solar technology works in the opposite way a traditional solar panel does.

While a regular solar panel captures energy from the sun to the Earth, the anti-solar panel traps energy traveling from Earth to space. Heat that is radiated off the Earth’s surface when it gets dark is captured by the anti-solar panel and used to generate usable energy.

“A regular solar cell generates power by absorbing sunlight, which causes a voltage to appear across the device and for current to flow. In these new devices, light is instead emitted and the current and voltage go in the opposite direction, but you still generate power,” Jeremy Munday, professor in electrical and computer engineering at UC Davis, said in a statement.

Currently, traditional solar panels are unable to produce energy at night or when sunlight becomes obscured. Instead, they provide power through net metering, in which surplus power is transferred to a public utility power grid.

“Solar cells are limited in that they can only work during the day, whereas these devices can work 24/7, which is the real advantage,” Munday told CNN. “Nobody wants to lose power once the sun sets.”

But the anti-solar panels are very much in the test phase. The prototypes made produce 50 watts of electricity per square meter under ideal conditions. That’s only about 25 percent of what solar panels can generate in a day.