More details emerge on Tesla Powerwall

We previously reported on Tesla’s announcement of home power storage units.

Now the company has released the price: $3,000 for seven kilowatt-hours or $3,500 for 10

Availability: Summer

The larger of the two battery models should keep an average-size home running for a day.

Tesla is launching this business partly because it’s already making vehicle batteries and can benefit from the economies of scale that come from producing both types. Another reason is that the market for energy storage is expected to grow in concert with the use of solar power. Tesla needs both electric vehicles and solar power to boom if it hopes to use the projected output from a $5 billion battery “gigafactory” it’s building in Nevada.