By Haley Zaremba of OilPrice
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Researchers at the University of New South Wales (UNSW) are developing a groundbreaking technology known as a “reverse solar” panel, or thermoradiative diode, which generates electricity by emitting infrared light (heat) into colder surroundings.
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This innovative device captures heat absorbed by the Earth during the day and releases it at night, providing a solution for generating power when traditional solar panels are inactive.
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While the current power output is limited, the ultimate goal for this technology is to power small devices overnight and potentially supply energy to satellites during their dark orbit phases.
The global solar energy sector has experienced exponential growth in recent decades due to falling costs and increasing demand. In 2025, the world added one-third more solar power than in the previous year, marking a significant increase in capacity. However, despite the affordability of renewables, challenges such as inadequate grid infrastructure and the intermittent nature of solar and wind energy threaten global energy security.
Unlike fossil fuels, which can be adjusted to meet demand, solar and wind power rely on natural factors beyond human control. Solar panel productivity is influenced by daylight hours and sunlight quality, often conflicting with peak demand periods.
To address these challenges, Australian scientists are developing a unique type of solar panel capable of generating energy at night. This innovative panel emits light instead of absorbing it, utilizing a semiconductor called a thermoradiative diode to convert heat into electricity. By capturing solar energy absorbed by the Earth during the day and releasing it as infrared energy at night, this technology aims to provide a reliable energy source.
Professor Ned Ekins-Daukes, leading the thermoradiative diode research team at UNSW, explains, “At night, the Earth emits heat into the cold universe.” Their objective is to harness this heat and convert it into usable energy.
According to a study in Nature Portfolio, “Solar cells generate electricity by absorbing photons from a hotter object, whereas thermoradiative diodes generate a current by emitting photons of infrared light into colder surroundings.” As long as the diodes are warmer than their environment, they will emit infrared radiation and produce electricity.
The UNSW team is building on previous research from Harvard and Stanford universities and was the first to demonstrate electrical power using these devices in 2022. While progress continues, the technology is still far from competing with traditional solar panels, generating only a small fraction of the electricity output.
In the future, thermoradiative diodes could power small devices overnight, potentially replacing or recharging batteries.
“Many people leave their devices on overnight, creating a light electrical load that these diodes could help supply,” says Ekins-Dauke. Moreover, these diodes may have significant applications, such as powering satellites in orbit. These satellites transition between light and dark phases every 45 minutes, making thermoradiative diodes a potential solution for generating power during dark, cold space conditions.
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