Published June 5, 2012
By Philippe Crowe
Toyota Motor Corporation (TMC) announced yesterday that it has developed a vehicle to home (V2H) system for the mutual sharing of power between electric-powered vehicles, such as plug-in hybrid vehicles (PHVs) and electric vehicles (EVs), and homes.
The V2H system will start testing, using Prius PHVs, at the end of 2012 in approximately 10 households as part of the Toyota City Low-Carbon Verification Project2 (Toyota City Project) that began in April 2010.
The newly developed V2H two-way electric power supply system can supply power from home to vehicle as well as from vehicle to home. An AC100 V inverter onboard the Prius PHV converts stored power into AC suitable for home use, while power flow is controlled according to communication between vehicle, charging stand and the home.
With this new method, low-carbon electricity (or "green" electricity) generated from regional or home solar generators, or low-cost late night electricity, can be stored in a vehicle's drive battery and then used to supply power to the household during peak consumption times. This kind of optimal energy flow can be automatically controlled by a home energy management system (HEMS).
Vehicle batteries can also be used as a power source in times of emergency by manually setting the electricity flow to supply power from the vehicle's drive battery through the charging stand to a home's lights and power outlets. According to Toyota, with a fully charged battery and full tank of gasoline, a Prius PHV can supply power for an average Japanese household (approximately 10 kwh) for four days.
Interest in smart grid technology and expectations for the effective use of electric vehicle batteries has increased due to recent anticipated electricity shortages in Japan, the beginning of full-scale renewable energy introduction and an increased need for emergency power supplies.
Households participating in the verification tests in Toyota City will use Prius PHVs, which can use the V2H system to supply electric power to homes, as well as function as conventional gasoline-electric hybrid vehicles once onboard electricity supply depletes to a certain level.
TMC developed its V2H system while closely complying with existing charging and communications specifications defined by the International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC), as well as with electrical safety standards and regulations.
Going forward, TMC hopes to promote the widespread use of V2H systems while closely studying—conscious of standardization trends—system, hardware, power generation and other relevant specification standards.
