Toyota Prius Will Power Your House!
They have developed a car-to-home or vehicle to home (V2H) power supply system, which works both ways. It allows the car to draw electricity from the grid during the night, when electric rates are cheaper, and the it can power the house during the day, when electric rates are considerably more expensive.
It may sound too complex, but everything will be done automatically, using a home energy management system (HEMS). The manufacturer will use a Prius in order to begin testing later this year. They claim that with a full tank of petrol and a fully-charged battery, the car could power an average-sized Japanese house for around 4 days.