Elon Musk, our lord and saviour...
Tesla CEO Elon Musk introduced the Powerwall at his company's design studio in Southern California. He said it's a "whole integrated system that just works and is connected to the internet." The battery packs are lithium-ion cells with a liquid thermal-control system. Powerwall -- which Tesla has been testing with select customers for a year -- connects to the internet so it can track power usage and share that information with utilities.
Read more at Engadget - http://www.engadget.com/2015/05/01/tesla-powerwall-battery/