While the amount of power that can be generated represents just one quarter, on average, of what a standard solar panel can produce during the daytime, the idea promises the ability of a solar farm to continue to produce a level of power as the evening begins.
Such a solar panel does not yet exist, what physicists from University of California – Davis have done is to produce a detailed concept study, paving the way for further research and the tangible prospect of producing solar-derived energy at night.
The idea is to develop a process based on the way that an actual star functions. This is a type of ‘reverse solar cell’, based on the fact that an object which is hot compared to its surroundings radiates heat in the form of infrared light. On this basis, a normal solar cell is cool compared to the sun, which results in it absorbing light.
In contrast, the new concept is to develop a thermoradiative cell, a device that is capable of generating power through radiating heat to its surroundings. Such a device could be used to capture and process the waste heat produced from running engines.
The science behind it is a cell whose temperature is higher than the environment temperature, which means the cell can radiate more photons than it absorbs.
If a series of thermoradiative cells are directed at the night sky, they would emit infrared light (because the cells are warmer than space). So, in contrast to a conventional solar cell, which produces power through the absorption of sunlight, the thermoradiative cell light is emitted and provided the current and voltage are set to move in an opposite direction, this generates power.
A further advantage is that such a device would also operate during daytime provide the cell is not subjected to sunlight.
The concept has been outlined in a paper issued by the journal ACS Photonics. The research is titled “Nighttime Photovoltaic Cells: Electrical Power Generation by Optically Coupling with Deep Space.”
