Solar panels are becoming increasingly popular for generating clean energy, but there is one major drawback to these devices: they need sunlight to work. However, researchers from the Soochow University in China developed solar panels that not only generate energy from solar energy, they also generate energy from raindrops.

Solar panels are excellent solutions in places with a lot of sunlight, but places wit a lot of rain (such as the Netherlands) generate considerably less energy.

To generate energy from rain, the new device has two transparent layers of polymers on top of the solar photovoltaic (PV) cell. When raindrops fall on the surface and roll off, the friction generates a static electricity charge. Unlike common solar panels, the new ones can generate energy in any daytime weather, and also at night, if it rains.

Using static electricity to harvest energy isn’t entirely new, and devices that do so are called triboelectric nanogeneratiors. However, the new device is much simpler than earlier attempts as well as more efficient, as one of the polymer layers acts as the electrode for both the triboelectric nanogenerator and the solar cell, creating a lightweight device.

The next step in the research is improving the output power efficiency, before looking for practical applications.

Photo: Oregon Department of Transportation