US electric carmaker Tesla Motors has unveiled batteries that can power homes and businesses as it attempts to expand beyond its vehicle business.
Chief executive Elon Musk announced the firm would build batteries that store solar energy and serve as a back-up system for consumers during blackouts.
The device would allow consumers to get off a power grid or bring energy to remote areas that are not on a grid.
Tesla plans to start shipping the units to installers in the US by this summer.
The system is called Powerwall, and Tesla will sell the 7 kWh unit for $3,000 , while the 10 kWh unit will retail for $3,500 to installers.