Two of Musks companies have partnered to build just that very system described in this article: http://www.solarcity.com/residential/energy-storage.aspx http:/

Two of Musks companies have partnered to build just that very system described in this article: http://www.solarcity.com/residential/energy-storage.aspx http://www.solarcity.com/residential/energy-storage.aspx Of course its marketed as backup power right now, but once battery costs come down this will be very viable.