http://www.usatoday.com/story/money/business/2013/05/12/battery-revolution-expands-solar-wind-energy/2133043/

Others are making their debuts this year, including a battery by Ontario, Canada-based Electrovaya that enables homes with solar panels to go entirely off grid or one by General Electric that will be paired with a Texas wind farm to provide continuous power.

Ontario-based Electrovaya plans to bring to the U.S. market this year a residential system, now being tested in Canada, that would install solar panels and a big-enough lithium-ion battery that homes could go completely off grid. Sankar Das Gupta, the company's CEO, says it would cost less than $10,000 for an average-size home to add such a battery to a solar array.