Generate electricity at night with solar cells
In order for solar cells to generate electricity, they usually need sunlight, which is naturally only available during the day. This reduces the productivity of the modules to zero at night. However, researchers at Stanford University have now succeeded in solving this problem and using solar panels to generate electricity at night. As the Interesting Engineering website reports, last October scientists working with electrical engineer Sid Assaworrarit tested a solar panel equipped with a thermoelectric generator on the roof of Stanford University to examine its night-time performance. Conditions were good as there was not a single cloud in the California sky for several nights. Under these conditions, the experiment was successful. According to Interesting Engineering, the tested device generated around 50 milliwatts per square meter at night. “I think that’s probably a record number,” Assaworrarit told the website. According to Assaworrarit, however, with a few improvements and an optimized location, power generation could be significantly increased. “The theoretical limit is probably around one to two watts per square meter,” the researcher announces. “That’s not a huge number, but there are many applications where this type of night energy would be useful.”
New solar cells could make batteries superfluous
The new technology could be useful wherever batteries previously had to be used to cover night-time electricity needs. Since solar modules usually only work during the day, the electricity generated must be stored in batteries for later use in order to provide energy at night. This circumstance has two disadvantages. Firstly, the necessary batteries are quite expensive and secondly, they lose a lot of capacity with the increase in charging cycles. Thanks to the nocturnal power generation with thermoelectric generators, many batteries can be dispensed with. Since the devices are also solid-state generators, Assaworrarit says their lifespan is pretty much infinite.
According to Interesting Engineering, about a billion people do not have access to a power grid. These people depend, among other things, on solar energy for their electricity supply. During the day you can rely on the solar panels in these areas, but this is not the case at night. The newly developed solar modules could help here. Many scientists and research projects around the world are just as dependent on nocturnal energy. For the continuous investigation of, for example, weather conditions or animal species in the most remote corners of the globe, the nocturnal solar panels could generate the electricity required and significantly reduce the need for batteries.
Infrared radiation makes it possible to generate electricity at night
The researchers at Stanford University use infrared radiation to generate electricity at night. “During the day, light comes in from the sun and hits the solar cell, but during the night something of the opposite happens,” Assawaworrarit told Interesting Engineering. The earth constantly receives an enormous amount of energy amounting to 173,000 terawatts from the sun. Clouds, atmospheric particles, and snow-covered surfaces would reflect about 30 percent of that energy directly back into space. The rest warm the planet. However, this heat does not remain on earth, except for a certain amount caused by the greenhouse effect. Practically every object that is warmer than absolute zero gives off the energy it has absorbed via infrared radiation. This is a type of light that cannot be perceived by the human eye due to its long wavelength. “The lights are actually off [vom Solarpanel], and we use that to generate electricity at night. “The photons that go out into the night sky actually cool the solar cell,” Assawaworrarit explains. The photons that go out skyward take the heat with them and leave the earth for space This temperature difference between the solar panel, which is a few degrees cooler, and the ambient air is used by Assawaworrarit and his colleagues to generate electricity via a thermoelectric generator.
Nicolas Flohr / Editor finanzen.net
Image sources: anatoliy_gleb / Shutterstock.com, Johannes Kornelius / Shutterstock.com