Elon Musk is at it again.
Rhett Allain has a nice article giving you some of the background physics you need to evaluate the effectiveness of the new Tesla's Powerwall home battery unit.
I would get this if it can be sustained for a full day with a single, full charge. So now I have to figure out how much my computers, entertainment system, freezer, refrigerators, and my central air system need! :)