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Toyota develops vehicle-to-home (V2H) power system; testing begins at the end of year

Energy management with the V2H system. Click to enlarge.

Toyota Motor Corporation (TMC) has developed a vehicle-to_home (V2H) system for the mutual sharing of power between plug-in vehicles—plug-in hybrid vehicles (PHVs) and electric vehicles (EVs)—and homes. The V2H system is to start testing, using Prius PHVs, at the end of 2012 in approximately ten households as part of the Toyota City Low-Carbon Verification Project (Toyota City Project) that began in April 2010.

The announcement follows on Nissan’s introduction of the LEAF-to-home V2H system, which can supply electricity from Nissan LEAF electric vehicles (EV) to residential homes when used with the “EV Power Station” unit—also a 6 kW charger for charging the LEAF—developed by Nichicon Corporation. (Earlier post.)

Toyota’s newly developed V2H two-way electric power supply system can supply power from home to vehicle as well as from vehicle to home. A 100 VAC 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 method, low-carbon 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. With a fully charged battery and full tank of gasoline, a Prius PHV can supply power for average Japanese household electricity use (approximately 10 kWh) for four days—i.e., when running the engine in the Prius PHV as a generator.

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, Toyota noted.

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.

In addition to the V2H system, TMC has also developed devices capable of supplying electricity from PHVs directly to home devices, for use at emergency shelters in the event of a disaster. The devices will be installed on the PHVs used in this round of the Toyota City Project tests.

The Toyota City Project awards eco-points to consumers who change their lifestyle habits to conserve electricity, and in 2011 there was an increasing trend toward households to use low-cost power to charge their vehicles. In light of the recent power supply shortages in Japan, the Toyota City Project is working to promote regional energy management that can respond to shifts in peak usage.

In response to the increasing need to control peak electricity use, the Toyota City Project will test synchronized automatic control between HEMS and regional energy data management systems (EDMS) this year. Existing energy usage optimization technology using household storage batteries will be expanded to V2H systems, making green electricity use even more effective while promoting a shift away from electric power consumption during peak-demand times.



Toyota's sales are in first place (again) in Canada four the last five months of 2012 and for the first time, over 10% of their sales are for electrified vehicles.

If the current trend continues, Toyota's Canadian sales could reach 15% electrified vehicles by this time next year and by the end of this year if production can keep up with demands.

Electrified vehicles could get a major boost when a major manufacturers make them with of Gordon Murray design without steel. His carbon like composite cost 1/25 of the current composite materials, is rustless, much lighter than steel and could last half a century. Batteries could be half size and less.


bout' time you could use the generator in the Prius to run your home.. that would be a popular option in hurricane prone areas.


Yes, if your car is parked in a hurricane proof garage.


Don't they know how sensitive EV owners are about their batteries? I wouldn't send my EV battery through more charge/discharge cycles just to trim peak levels unless I was paid to do so at a level which made me comfortable.

Long term this is good, but short term, EVs are just getting started, give them a break - don't make them do double duty so early.


Why not just buy a generator and a few litres of gas or diesel?


Shame on you mahonj! I agree with TM. It seems much too early to be trying to make V2H viable - considering the nascent state of EV battery packs. And the additional hardware for the interface is bound to be expensive.

What we do see is a formidable scramble by all energy makers to position themselves as value add products. This scramble is coming about due to the imminent arrival of very low cost energy. Abundant Clean/Green Energy as NASA describes it.


"Why not just buy a generator and a few litres of gas or diesel?"

another gadget you need to store in the garage, the Prius (and all hybrids) has a built-in gasoline tank, with convenient wheels attached for taking the large tank to the gas station, very safe also from a fire point of view. The generator in the Prius is also much more efficient, cleaner and quieter than any standalone generator I have ever seen, and it even has an electric starter.. no more cranky starter rope to pull at 4AM when you are half asleep.

Also, poisonous CO emissions must be much lower than any small generator on the market.

Things like this will promote hybrid sales in places like Florida, not nice in the summer heat when you lose power for 2 weeks.


A 4.4 KWH prius battery will not help you for a 2 week outage unless you mean by preventing a 2wk outage. But the utility company should be able to prevent the 2 wk outage, and that is an underlined, "should".


I am talking about the gasoline generator that is built-in to every Prius.. diesel-like efficiency but with a clean exhaust. Gasoline is widely available way before the electrical infrastructure is rebuilt/repaired.

The battery in PIP is too small to do any good as a replacement for a generator.



Who says the battery suffers from that? In the case of the Nissan LEAF, the V2H system is limited to a friendly 6.6 kWh, or ~0.25 C. Furthermore, shallow cycles degrade batteries not as much as deep cycles. So simply keep an eye on minimum battery level and it will not suffer. And lastly, time is also a factor in battery degradation, whether you use it or not. Put it on a shelf for 6 years and capacity will decline. Your concerns are unnecessary, especially if this is intended to be used in calamities, not on a regular basis.


A Prius, with the ICE running to recharge the battery, can certainly supply more than enough e-energy for a large house as long as it is fueled. It has a rather powerful on board genset.

Kit P

If a hurricane is coming, get in your car and leave. Anyone who owns an emergency geneator is too stupid to stupid to use it safely. If you loose power and are in a safe place, pretend you are camping. Dust of the chess set although anyone who needs this advice should play checker or shoots and ladders.


I was without power for a week after an ice-storm, so it's not just hurricanes.
Hurricanes: at the very least you could run your refridgerator and not have all the food spoil.
Would be an additional selling point (for Prius) along gulf coast and Carolinas.


Two weeks in an ice storm sounds like fun..You can also use it to run your furnace.. apparently that does not consume too much power

Coke Machine

My 4kW Uni-Solar system will keep me OK during the day after the hurricane as there is always rapid clearing after a fast moving front, and thus pretty sunny, the 17.5 kw gas generator will keep everything fine at night. It would be nice though if someone invented a generator to attach to the 3 pt hitch of my John Deere diesel tractor so I could get rid of that 17.5 kW beast. It's got plenty of torque.

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