Can't we all just get a bong?
The value of the battery is it overcomes the bursty nature of demand, which might trigger a coal plant coming online and ramping up to meet a peak that has already passed. It's isn't rocket science, that's another Elon Musk company.
edit:
Once the concept is proved out using environmentally-costly batteries, we can get serious:
http://blogs.worldwatch.org/revolt/u...a-grand-scale/