The advent of new solar panels: can also generate electricity at night

According to the paper published in Applied Physics Letters, it acts like a classic solar panel, converting sunlight into electricity during the day. At night, embedded thermoelectric generators (TEGs) "harvest electricity from the temperature difference between the photovoltaic cells and the surrounding environment."

They attached photovoltaic cells with an insulating material called a thermoelectric module, said Shanhui Fan, an electrical engineer at Stanford University who led the research. The material acts like a hydroelectric dam, absorbing heat flow and generating energy from it.

The technology works by trapping the heat of the day into a radiator. Then, when this energy naturally radiates back into space, some of it can be captured by the TEG and a unique material that can capture thermal wavelengths.

Despite the breakthrough, many challenges remain with the technology. First, the power generated at night is only 50mW/sqm, compared to about 1000 W/sq.m for a standard solar panel. Second, the heat cools down relatively quickly, which translates into a decay in the amount of electricity produced.

But the technology is exciting and could potentially be used in low-power applications or where there is a reliable source of heat, like lighting up LEDs, or charging phones or sensors.