With the various tax incentives available, there is an increasing interest among homeowners in incorporating some sort of renewable energy system to help get partially or completely off the grid. The problem is that unless you live adjacent to a hot spring that you can use for geothermal, the other primary sources are wind and solar power. Both wind and solar are great, except for their somewhat intermittent performance. For that reason, you need some kind of battery buffer system to store energy when the sun is shining or the air is in motion so that you can use it at night or when it's calm.
Depleted electric vehicle batteries have been discussed as a good source for these buffers, but at the moment there isn't a readily available supply. Panasonic plans to step up to the plate and produce a lithium ion battery pack specifically for home storage use beginning in 2011. The home storage battery was initially developed by Sanyo, but Panasonic recently acquired a controlling interest in that company. They are now working together to bring the system to market and will make further announcements in the first half of 2010.