Panasonic Delivering a Lithium Storage Battery That Can Power Your Home For a Week [Batteries]

After officially taking over Sanyo earlier this week, Panasonic is hitting the ground running with a joint venture aimed at developing a powerful lithium-ion storage battery than could store enough juice to power an average [Japanese] home for a week.
The battery will also include a system that will allow users to monitor their electricity usage through their televisions. Seems like a viable alternative to solar batteries and fuel cells, but I'm curious to know how a week of powering a Japanese home equates to powering a typical American home. Either way, the technology won't be available until sometime in 2011.
[Gizmodo via Physorg]