(REPOST: CNN)

Though renewable energy is on the rise, a significant challenge has always been finding ways to store it on days when the sun doesn’t shine and the wind doesn’t blow. In the small Bavarian town of Wildpoldsreid, technology company Sonnen is creating a battery that not only stores residential renewable energy, but allows users to even trade their excess energy with others.

“The specialty about Sonnen is that we provide homes with battery storage systems and make them more or less independent by connecting them to a virtual power plant called the Sonnen Community,” says CEO Christoph Ostermann.

Last year the company started selling their batteries to homeowners who do not have access to renewable energy collection devices such as wind turbines and solar PV systems. By decoupling the place of production and the place of consumption, Ostermann says more people in urban areas can begin using more renewable energy, even if they don’t produce it themselves.

“The energy world is becoming more and more decentralized and digitalized,” he says, “and our aim at the end of the day as a company is to provide, clean and affordable energy for all.”

The company started in 2010, and has sold around 30,000 battery systems, 75 percent of which in Germany.

The battery starts at approximately $7,000 and with an expected lifetime of 20 years, Ostermann says people can save money compared to buying power from the grid.

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