The home energy storage battery is the latest breakthrough in household energy use and conservation. In simple terms it does three things: first, during power outages control (through renewable power sources such as solar panels and wind turbines) makes sure there is still some on demand; later, it provides electricity at full afternoon heat; finally when rates are low people may use more energy which goes unrecorded since they are no longer generating. Technologies include devices for high density energy supply, its modular construction which allows expansion step by step, and a control system for smart energy management. Basically the very same system of a smart grid we often talk about. It is used in households all the way up to small commercial set-ups where users need to be energy self-sufficient and energy efficient and get their own electricity at low rates.