Can solar panels generate energy even when the sun isn’t around? In a major breakthrough, researchers at the University of California have designed a unique night solar panel (NSP) that can produce 50 W under ideal conditions at night, one-fourth of what traditional solar panel produce during the day.
In their paper entitled ‘Nighttime Photovoltaic Cells: Electrical Power Generation by Optically Coupling with Deep Space’, academics Tristan Deppe and Jeremy N. Munday explain that through the use of the night sky as a heat sink and the earth as a heat source, a photovoltaic cell can be devised that generates energy at night. Munday elaborates, “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. You have to use different materials, but the physics is the same.”
In other words, traditional solar panels operate on the concept of a cool object (solar panel) absorbing light from a hot object (the sun), NSPs (hot) would reverse the concept and would radiate heat as infrared light into their cool surroundings. Munday also alleviates concerns about the panels’ power and fuel use, by theorising that they could work 24/7 and utilise residual energy from existing industrial processes, thereby not posing further challenges on the road to carbon-neutrality.
Munday and his team are currently working to make practical prototypes out of the theory advanced in this research paper, and have been successful in developing one that generates one-fourth of the energy produced by a conventional solar panel. With increased technological advancement, public support and government investment, especially under the Biden administration, night solar panels for ordinary consumption, though a distant dream at the moment, might arrive sooner than you think! This technology would be especially useful for times and places of low annual daily sunshine hours, such as the winter season and remote locations (provided effort is made towards installation technology too) when energy demand (for heating, lighting etc) is high and supply is low, resulting in high cost. Additionally, the device appears to be flexible and adaptable: if not positioned facing the sun, it can perform during daytime as well; it can also balance the power grid over the day-night cycle.
The solar industry has seen record investments and solar farm deals in the past year and the current year looks promising as well. NSPs have a long way to go before competing in the market with conventional solar panels in terms of quality, efficiency and cost, but the time of solar panels continuing to work at night may not be very far.