'REVERSE' SOLAR PANEL TECHNOLOGY STILL WORKS WHEN THE SUN GOES DOWN
Prof. Anil A. Tekale, Assistant Professor,
Department of Electrical Engineering, SVERI’s College of Engineering, Pandharpur
Traditionally solar panels, or photovoltaic cells, have suffered from the effects of changeable seasons and the fact that they don't work at night. From cloudy weather to dwindling day length, it’s not just the dusk that stops them from providing a viable renewable energy source for people in many parts of the world.
The nighttime solar cells would essentially work the same way as their daylight counterparts but in reverse. Every night, heat from the sun escapes the earth in the form of infrared radiation in order to keep the planet at a constant temperature.
“A regular solar cell generates power by absorbing sunlight,” but, in these new devices light is instead emitted and the current and voltage go in the opposite direction but you still generate power.
The device would be able to generate up to 50 watts of power per square meter, a quarter of what conventional panels can generate in the daytime. They would also work in the daytime if the light was blocked or they were pointed away from the sun. Some research even suggests that we could use them to harness the waste heat generated by machinery. "In this concept we have to use different materials but the physics is the same.”
Far from a new idea, people have been using similar technology to achieve nighttime cooling for hundreds of years. You are using the same theory when you open your windows and doors after a hot day to cool down your house. Essentially this form of passive cooling uses the night sky as a massive heat sink, drawing warmth away from the earth once it gets dark.
Last year, saw scientists similarly try to use the differences in day and night temperatures to generate electricity. They managed to prove that the technology did work but there is a long way to go when it comes to efficiency and performance. These reverse solar panels may only be prototypes but a similar idea could operate around the clock providing energy in places with changeable weather conditions and low light levels.
The approach works a bit like a regular solar cell in reverse. A conventional solar cell is cool compared to the sun, so it absorbs light. But if you take a warmer object and point it someplace cold it will radiate heat toward it in the form of infrared light. That’s what the UC Davis researchers have been doing, directing their solar cells at the sky, where it will radiate infrared light because it is warmer than outer space. Due to some smart physics and a device called a thermoradiative cell which generates power by radiating heat, they believe they may have come up with a breakthrough type of solar cell.
“As you know, in many places solar cells work great for about eight hours per day, but after the sun goes down we need other power sources or storage,” Jeremy Mundey, professor in the Department of Electrical and Computer Engineering at UC Davis, told Digital Trends. “That is where this concept comes in. I like to think about solar cells as being kind of like heat engines without the moving parts. You take a semiconductor that is doped in a particular way, and you put it between a hot object and a cold object. For a normal solar cell, the hot object is the sun and the Earth is the cold object. For our devices, the Earth becomes the ‘hot’ object and deep space, with a temperature of 3 K (negative 454.27 Fahrenheit), becomes the cold object.”
Reference
2.https://www.modi2.com/tech/reverse-solar-panel-technology-still-works-when-the-sun-goes-down/
3.https://www.digitaltrends.com/cool-tech/reverse-solar-panel-power-at-night-outer-space/?amp
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