It may be possible to generate solar power at night

A huge step forward in thermal capture technology means it might not be too long before we’re harnessing energy from light, after dark. 

Solar power is one of the great hopes of an energy sector that desperately needs to decarbonise, with heat from the Sun’s rays hitting panel arrays in vast ‘farms’ or on private properties and then converted into electricity. Until now, though, critics have cited a number of problems, not least the inability to continue generating power at night and difficulty storing any energy captured during the day for later use. Now scientists at the School of Photovoltaic Renewable Energy Engineering at the University of New South Wales, Sydney, believe they have found a solution to one of those obstacles. 

It all comes down to a major breakthrough in thermal capture technology, which comes in the form of a device – the thermo-radiative diode – which is capable of converting infrared heat into electrical power. The system is comparable to the principles of night-vision goggles. At the time of writing, only a tiny amount of power has been generated with this model, equivalent to 0.001% of the output from a standard solar cell. However, the team responsible claim proof of concept is key, and if the design can be upscaled it could be a watershed moment in the development of solar technology and the transition to a world powered by green energy.

Those involved in the project are now working towards new device designs and refining the existing prototype to harness solar energy at night. The team are inviting expressions of interest from potential industry partners. 

‘In the late 18th and early 19th Century it was discovered that the efficiency of steam engines depended on the temperature difference across the engine, and the field of thermodynamics was born. The same principles apply to solar power — the sun provides the hot source and a relatively cool solar panel on the Earth’s surface provides a cold absorber. This allows electricity to be produced,’ said Exciton Science Associate Investigator and research team leader, Nicholas Ekins-Daukes.’

‘However, when we think about the infrared emission from the Earth into outer space, it is now the Earth that is the comparatively warm body, with the vast void of space being extremely cold. By the same principles of thermodynamics, it is possible to generate electricity from this temperature difference too: the emission of infrared light into space,’ Nicholas continued. ‘We usually think of the emission of light as something that consumes power, but in the mid-infrared, where we are all glowing with radiant energy, we have shown that it is possible to extract electrical power. We do not yet have the miracle material that will make the thermo-radiative diode an everyday reality, but we made a proof of principle and are eager to see how much we can improve on this result in the coming years.’