These solar cells also produce electricity at night

A team of Stanford researchers has unveiled solar panels capable of operating at night, generating enough electricity to charge a phone or run an LED lamp.

Exploiting temperature differences to produce electricity at night

When solar radiation reaches a photovoltaic panel, the cells that make it up (made up of layers of a semiconductor material, usually silicon) generate a flow of electricity. At night, these devices radiate the heat stored during the day into space, whose temperature is around 3 kelvins (-270.15°C), meaning that they become noticeably colder than the surrounding air.

In the context of work published in the journal Applied Physics Letters, Shanhui Fan and his colleagues attached a thermoelectric generator to a standard solar cell, in order to exploit these temperature differences to produce energy.

Pointed at a clear night sky, the modified solar cell was able to generate 50 milliwatts per square meter. Although this is only 0.04% of the energy produced by a standard solar cell during the day, this amount of electricity would be enough to power low-power devices, such as a smartphone charger or low-power LED lighting. consumption.

A direct source of energy

” The advantage of this approach is that it provides a direct source of energy at night, without storage “, highlighted Fan. “ Batteries can be expensive and temperamental, require a lot of energy to manufacture, and they can contribute to water and air pollution if not properly disposed of.. »

While unlikely to replace existing large-scale energy infrastructure, these nocturnal solar cells involving only a limited number of modifications could prove particularly useful for certain tasks requiring a small amount of current in regions isolated from the globe.

The authors of the study point out that this is only a prototype, and that the configuration of the device could be easily improved so that it generates more energy.