Tesla Motors on unveiled Tesla Energy on Thursday (30 April) - storage systems or batteries for homes, companies and utilities that will expand its business beyond electric vehicles and tap into a fast-growing area of the energy industry.

Chief executive Elon Musk said the company's goal was to "Welcome everyone, basically to the announcement of Tesla Energy. What I am going to talk about tonight is a fundamental transformation of how the world works, how energy is delivered across the earth".

In Tesla's view, such storage systems could become part of a fossil-fuel-free lifestyle in which people can have solar panels on their roof generating electricity to power their home and recharge their electric car batteries.

The smallest battery unveiled on Thursday, known as Powerwall, is housed in a six-inch-wide container that is meant to be hung inside a garage or on the outside wall of a house.

At $3,500 (£2274) for a 10kWh model, excluding inverter and installation prices, the Powerwall can be used for backup power or to store solar energy.

Musk said: "If you're thinking of buying a battery, well what does this provide you? Well it gives you piece of mind, if there is a cut in the utilities you're always going to have power. If you're in a place that is very cold, you don't have to worry about being out of power if there is an ice storm.

"You could actually go, if you want, completely off grid. You could take your solar panels, charge the battery packs and that's all you'd use. So it gives you safety, security and it gives you a complete and affordable solution, and the cost of this is $3,500."

Tesla has several hundred batteries installed with SolarCity systems in California already. The growth of those projects has been helped by a subsidy from California's public utility regulator.

The CEO surprised the audience by announcing that the evening had in fact been powered by "stored sunlight".

"Oh, wow this grid is actually zero, this entire night has been powered by batteries. (clapping and cheering) Not only that, but the batteries were charged by the solar panels on the roof of this building. So this entire night, everything you are experiencing is stored sunlight," Musk said.

Utilities have also been seeking out energy storage to help manage increasing amounts of renewable energy on the grid. To address that market, Musk unveiled what he called the "power pack," a 100 kWh battery block that is meant to help smooth out power from intermittent solar and wind energy production or add energy to the grid quickly when demand levels are high.

Tesla already has several utility-scale batteries deployed on the grid in California, which requires its biggest utilities to source large amounts of energy storage.

"So we want to show people that most importantly that this is possible, if you look at that, that is the future we could have, where the curve slowly rolls over and goes to zero, no incremental CO2. That's the future we need to have, and that's something that, and the path that I've talked about, the solar panels and the batteries. It's the only path that I know that can do this and I think it's something that we must do and that we can do and we will do," Musk said.

Tesla will initially manufacture the batteries at its automobile factory in California but will move production to its planned "gigafactory" in Nevada next year.

Deutsche Bank estimated sales of stationary battery storage systems for homes and commercial uses could yield as much as $4.5bn in revenue for Tesla. Analysts expect Tesla will build stationary storage systems around the same basic batteries it will produce for its vehicles at the large factory the company is building in Nevada.

Though valued at just $200m in 2012, the energy storage industry is expected to grow to $19bn by 2017, according to research firm IHS CERA.

Tesla is not the only player in energy storage. Coda Energy, which rose from the ashes of a failed EV maker and is now owned by Fortress Investment and startups backed by the likes of Total, GE and Siemens are among the many companies going after shares of the stationary storage market.

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