Solar panels are photoelectric semiconductor sheets that directly generate electricity from sunlight. As long as a certain amount of light is met, light energy can be converted into heat energy. Recently, scientists at Stanford University have developed a new technology that allows solar panels to generate electricity in the dark.
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According to a paper published in Applied Physics Letters, it acts like a classic solar panel, converting sunlight into electricity during the day. At night, an embedded thermoelectric generator (TEG) "harveses electricity from the temperature difference between the photovoltaic cells and the surrounding environment."
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As we all know, photons transfer kinetic energy to molecules after colliding with molecules of matter, and the molecules start to generate heat when their kinetic energy rises. Therefore, any object except absolute zero will emit infrared rays. The only thing that can feel the existence of infrared rays is its thermal effect, but this process It is by no means a one-way street.
Solar radiation heats the earth during the day and is released as infrared light at night. Scientists have developed a thermal radiation diode made of the same material as infrared night vision goggles, which converts thermal energy radiated from heat sources to cooler areas into electrical energy.
Switching the power converter from the cold end to the hot end to make solar panels, the researchers said this is the first time this technology has been realized in the world, although it can only generate about 1/10 of the electricity of solar panels at night, as long as it continues to improve, In the future, it may be possible to create devices that run solely on the heat emitted by humans or animals.
They attached an insulating material called a thermoelectric module to the photovoltaic cells, said Shanhui Fan, an electrical engineer at Stanford University who led the study. The material acts like a hydroelectric dam, absorbing heat flow and generating energy from it.
The technology works by trapping daytime heat into the radiator. Then, when this energy is naturally radiated back into space, some of it can be captured by the TEG and a unique material that traps thermal wavelengths.
Despite this breakthrough, the technology still has many challenges. First, the power generated at night is only 50mW/square, compared to about 1000W/square for standard solar panels. Second, the heat cools off relatively quickly, which translates into decay in the electricity generated.
But the technology is exciting and could potentially be used in low-power applications or where there is a reliable heat source, such as lighting LEDs or charging phones or sensors.
