LOS ANGELES (AFP) - Electric car pioneer Tesla Motors unveiled a home battery on Thursday which its founder Elon Musk said would help change the "entire energy infrastructure of the world."

The Tesla Powerwall can store power from solar panels, from the electricity grid at night when it is typically cheaper, and provide a secure backup in the case of a power outage.

In theory, the device, which typically would fit on the wall of a garage or inside a house, could make solar-powered homes completely independent of the traditional energy grid.

It is about 15cm thick, 122cm tall and 91cm across.

"The goal is complete transformation of the entire energy infrastructure of the world, to completely sustainable zero carbon," Musk told reporters shortly before unveiling the Powerwall in a warehouse outside Los Angeles.

Initially the device, which will cost US$3,500 (S$4,640), will go on sale in the United States later this year. But the aim is to roll it out internationally some time next year.

Germany is seen as a key market for the product because the country has among the highest take-up of solar energy in the world, Musk said.

But it could also be a huge boon for under-developed regions, where power is often unreliable at best, despite abundant solar energy - and he compared the potential to that of the way cellphone technology has expanded.

"It's analogous to the way mobile leap-frogged landlines," Musk said.

"This is going to be really great for the poorest communities in the world," he said. "This allows you to be completely off grid."