Thu. Jun 8th, 2023

The production of energy is possible because of a heat difference. An unusual physics quirk causes solar panels to become colder than the surrounding air, which may harvest electricity.

Recently, solar panel prices have dropped significantly, making them an essential renewable energy source. They only work during the day. What if the energy generated by solar panels could be used at night? Researchers at Stanford University have developed a solar cell to the end. 

The discovery coincides with a surge in solar-related employment and household installations. Research published in Applied Physics Letters claims that this idea can provide a continuous renewable energy source both during the day and night. – One of the new methods uses a surprising characteristic of solar cells.

There is light from the Sun that hits the solar cell during the day; at night, something similar takes place, according to study author Dr. Sid Assawaworrarit. As with anything else emitting heat above absolute zero, solar panels are a likely culprit. We use the light from the solar panel to create power during the night.” The photons that are sent into the night sky cool down the solar cell,” he explains.

Photons take the heat with them as they leave the panel’s surface. Even on a cloudless night, the surface of a solar panel will be a few degrees colder than the ambient air. He and his colleagues take advantage of this temperature differential, says Dr. Assawaworrarit. Using a device known as a thermoelectric generator, heat may be captured from the warmer air and transferred to the colder solar panel for use as electricity.

Solar panels on a Stanford rooftop yield roughly 50 mW/m2 of power on a clear night, according to Dr. Assawaworrarit’s test array. The gadget might produce twice as much power with a few adjustments and the correct placement. Utilizing an underutilized renewable energy resource, this approach is novel. The Sun continuously sends 173,000 terawatts of energy to the Earth. Around one-third of the energy is reflected into space by the atmosphere’s constituent particles and reflective surfaces like snow-covered mountains. It also acts as a blanket, warming everything from the ground up to the atmosphere. This vigor, however, is short-lived.

Earth’s energy production is about equal to its intake, except for the additional heat trapped by greenhouse gases due to human activities during the Industrial Revolution. Consequently, the planet emits an incredible amount of infrared radiation. Large amounts of energy are carried by these emissions, which have wavelengths too long to be seen by the human eye. Moreover, half of the solar energy that hits the Earth is reflected in space through this mechanism.

One billion people do not have access to electricity at this time. Solar power is available throughout the day, but Assawaworrarit points out that there isn’t much to do once the sun goes down. Researchers have discovered a method for supplying off-grid and mini-grid applications, where solar cell installations are becoming increasingly common, with illumination and power backup for the night.

A mini-grid is a small, self-contained electricity network. These are the go-to options when a population is too tiny or too far away to justify extending the grid to reach them. The thermoelectric generators used in these solar panels are solid-state instead of batteries, which degenerate after a few thousand charge cycles.

Additionally, researchers employ a massive network of environmental sensors to monitor anything from the weather to invasive species in remote areas. A little quantity of nighttime power from solar panels might prevent the requirement for batteries and their related maintenance and repair expenses in these applications. The team is still working on energy production from this technology.

Assawaworrarit believes that achieving a power density of one watt per square meter would be highly desirable in terms of efficiency. Infrared energy that is currently squandered at night may be captured in this type of output could be achieved.