File photo: Homeowners with solar panels to capture solar energy alsouse batteries to store the solar energy for use at night or when sunlight is low.

Cape Town - Researchers at Ohio State University say they have invented the first solar cell that stores its own power.

The device, which is to be patented, is a solar cell and a rechargeable battery that runs on light and air.

Yiying Wu, professor of chemistry and biochemistry at the university, writing of his findings in Nature Communications said he and his team had succeeded in combining a battery and a solar cell in one hybrid device.

Homeowners with solar panels use batteries to store energy. These batteries are expensive. Wu says the ideal would be to use a solar panel to capture the light and a cheap battery to store the energy.

“We’ve integrated both functions into one device.”

Wu believes this would reduce the cost by 25 percent.

The researchers say the invention also solves a longstanding problem by eliminating the loss of electricity that occurs when electrons travel between a solar cell and an external battery. Solar power systems lose about 20 percent of the energy.

With the new design, light is converted to electrons inside the battery, so nearly 100 percent of the energy is saved.

The researchers say the key to the invention is a mesh solar panel, which allows air to enter the battery, and a special process for transferring electrons between the solar panel and the battery electrode. They built on their earlier invention of a “breathing battery”, one that takes in air when it discharges and “breathes out” when it charges.

Solar cells are normally made of solid semiconductor panels that block air from getting into the battery.

The researchers came up with a permeable mesh solar panel of titanium gauze, a flexible fabric on which they grew vertical rods of titanium oxide like blades of grass. Air passes freely through the gauze, while the rods capture the sunlight.

When sunlight hits the mesh panel, it creates electrons. Inside the battery, these electrons create energy by breaking down lithium peroxide into lithium ions and oxygen. The oxygen is released back into the air, and the ions are stored in the battery.

Cape Times