Solar panels are an increasingly popular form of renewable energy. Whether using off-grid, micro-grid, or as part of a larger energy system, these panels are becoming more accessible and affordable. They convert the sun’s radiation into usable energy, which is usually stored in batteries and ready to use once the sun goes down. A team at Stanford University is working on a solution to the problem of bulky batteries and dark hours. As announced in the journal Applied Physics Letters, a new type of night-friendly solar panel will provide energy around the clock, harnessed from the sun as well as from earth.
The new device is designed to capture solar rays during the day in the same way that normal solar panels do. When night falls and the solar panel cools, it rests at a temperature slightly below the air temperature. The differential can be controlled by a heat conduction generator module (TEG), which generates voltage and current from a temperature gradient (or difference).
The atmosphere around the battery is heated by a new source of heat: earth. Our planet absorbs the sun’s heat during the day and radiates it back into space. The new device can generate 50mW /m2 of power on a clear night with an open circuit voltage of 100mV. This is a higher energy level than other efforts to capture energy at night. The device is made from off-the-shelf materials, so the team hopes it will be useful in many parts of the world where people lack power grids. However, further improvements are needed to improve efficiency before we can expect to see solar panels on roofs at night.
Researchers at Stanford University have developed a solar panel that can collect solar energy during the day, but can also collect thermoelectric energy at night
Solar panels use heat emitted from the Earth itself to operate at night, eliminating the need to store daytime energy in batteries