Without a way to store their power, no number of solar panels will free a home from the electrical grid. Until now. Researchers at Utah-based Ceramatec have developed a new battery that can be scaled up to store 20 kilowatt-hours—enough to power an average home for most of a day.

An easy sell for solar users, but it could also allow the grid to stockpile energy during less expensive off-peak hours. The new battery runs on sodium-sulfur—a composition that typically operates at greater than 600 F.

“Sodium-sulfur is more energetic than lead-acid, so if you can somehow get it to a lower temperature, it would be valuable for residential use,” Ralph Brodd, an independent energy conversion consultant, says. Ceramatec’s new battery runs at less than 200 F.

Ceramatec says that batteries will be ready for market testing in 2011, and will sell for about $2000.

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