According to researchers at the University of California, Davis, ‘anti-solar panels’ could create energy during the night without the need for sunlight. A team published a paper stating that using invisible infrared light from the Earth, a thermoradiative cell can produce electricity.
Normal solar panels use photons from the sun’s radiation to excite electrons and produce electricity using photovoltaic cells. These thermoradiative cells can reportedly produce 25% of the energy standard solar panels produce during the day but without the need for light by harnessing invisible infrared radiation when pointed at the Earth. To make this possible, the cells need to be made of something that can capture extremely long-wavelength radiation – the UC Davis team is currently looking at mercury alloys to achieve this.
Jeremy Munday, an author of the paper linked above and a professor in the Department of Electrical and Computer Engineering at UC Davis, told Inverse:
You have heat energy coming from the sun toward the Earth, and that normal solar cell picks off that energy as it’s transmitted from the sun to the Earth, so basically you need these two different temperature bodies and some way of converting that power.
What this nighttime device does is a similar sort of thing — where it’s just taking a hot body and a cold body — but now the relatively hot body is the Earth and space is the cold body. As this heat is flowing from the Earth to outer space, it’s picking that off and converting that into power.
This differential in energy between the Earth and deep space is what the team is focussing on harnessing with this fairly new idea. The abstract of the piece dives into what they want are wanting to achieve:
Photovoltaics possess significant potential due to the abundance of solar power incident on earth; however, they can only generate electricity during daylight hours. In order to produce electrical power after the sun has set, we consider an alternative photovoltaic concept that uses the earth as a heat source and the night sky as a heat sink, resulting in a “nighttime photovoltaic cell” that employs thermoradiative photovoltaics and concepts from the advancing field of radiative cooling. In this Perspective, we discuss the principles of thermoradiative photovoltaics, the theoretical limits of applying this concept to coupling with deep space, the potential of advanced radiative cooling techniques to enhance their performance, and a discussion of the practical limits, scalability, and integrability of this nighttime photovoltaic concept.
Other research teams have been looking into this technology for a while now, and it certainly won’t be long until we see a breakthrough in nighttime solar systems. The next question is how it’s going to be introduced into the current infrastructure.