Recently, researchers at Stanford University have built a prototype of a small solar panel that can generate electricity day and night.
According to a paper published in Applied Physics Letters, it's like a classic solar panel that converts sunlight into electricity during the day. At night, the embedded thermoelectric generator (TEG) "draws its energy from the temperature difference between the photovoltaic cell and its surroundings."
Shanhui Fan, an electrical engineer at Stanford University who led the study, said they attached an insulating material called a thermoelectric module to the photovoltaic cells. The material is like a hydroelectric dam that absorbs heat streams and generates energy from them.
The technology works by trapping heat from the day into a heat sink. Then, when this energy is naturally radiated back into space, some of that energy can be captured by TEG and a unique material that can capture thermal wavelengths.
Despite the breakthroughs, many challenges remain with the technology. First, the power generated at night is only 50mW/flat, while the standard solar panels are about 1000 W/flat. Second, the heat cools down relatively quickly, which translates into attenuation of the generated electricity.
But the technology is exciting and could be used in low-power applications or where there is a reliable heat source, such as lighting up LEDs or charging phones or sensors.
Source: Fast Technology