Indeed, Tesla Gigafactory is a vertically integrated venture. It has wind, solar, power storage devices in addition to rechargeable batteries for e-cars. It's a natrural extension for rechargeable batteries for use in the homes as a backup or supplementary power source.

Businesses and homes in "cottage areas" have been using back-up power units for emergencies. For home owners the back-up power would be for heating and water supply (from wells or lakes). Affluent people would spend several thousand dollars for those systems. However, there are a lot more people who would not mind getting a backup system for basic requirements such as keeping the water pipe (and people) from freezing, some heating, keeping some light on. Of course, the computers would need a power source. Diito for smart phones, etc... that need to be charged.

These fence sitters would jump at the opportunity if the price is a bit lower, say ~$2000, and the system can provide about 1 week of emergency power for an average and frugally managed home in North America. It would be a bonus if the batteries can be recharged with solar or wind. The rechargeable system could then be used as subplementary source of power to reduce the demand from the grid.

In summary, with continuing improvement in the LiB technology (which require high quality graphite) there is a good future for rechargeable batteries for home use, as I see it.

Tesla: Better watch out, Apple is in the battery business as well (for smart phone and the likes, but it may want to invade the homes as well). With some $160B cash available it can gobble up the $5B Gigafactory (even Tesla at $25B) in one gulp.

goldhunter