Tesla's announcement shows the coming revolution in energy storage

Washington

LATE Thursday, the glitzy electric car company Tesla Motors, run by billionaire Elon Musk, ceased to be just a car company. As was widely expected, Tesla announced that it is offering a home battery product which people can use to store energy from their solar panels or to backstop their homes against blackouts, and also larger scale versions that could perform similar roles for companies or even parts of the grid.

For homeowners, the Tesla Powerwall will have a power capacity of either 10 kilowatt hours or seven kilowatt hours, at a cost of either US$3,500 or US$3,000. The company says that these are the costs for suppliers and don't include the cost of installation and a power inverter, so customers could pay considerably more than that.