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DENSO develops vehicle-to-home power supply system for electric vehicles

DENSO’s H2V system leverages its HEMS. Click to enlarge.

DENSO Corporation has developed a vehicle-to-home (V2H) power supply system for electric vehicles (EV), which is designed to work in coordination with DENSO’s home energy management system (HEMS), which was introduced earlier this year. (earlier post).

The V2H system can quickly charge an EV with direct current from the HEMS storage battery, and can supply the electricity in the EV back to the household. In addition, the system can efficiently distribute electricity, including power generated by residential photovoltaic systems (solar panels), to the EV and to the home through the coordination of the HEMS. The two main features of the new system are as follows:

  1. Quick recharging function using a HEMS storage battery. Because an EV is battery-powered, the battery needs to be quickly charged for the car to be practical and functional, particularly when the battery level is low. However, a quick charger uses a substantial amount of power, resulting in an increase in the consumer’s electricity contract/bill and it is difficult to install for household use.

    DENSO’s new system can quickly supply the electricity that is stored in the HEMS storage battery to the EV when charging at home, which doesn’t require a dedicated charging device. Within just 15 minutes of charge using the DENSO system, the EV can travel up to about 20 km (12.4 miles).

  2. Eco-V2H function. The HEMS can estimate the daily EV travel distance and household power consumption to best manage the charging and discharging of the electricity of EV and HEMS battery unit. Also, to achieve local production of energy for local consumer consumption, the energy surplus produced by the photovoltaic system can be stored in the EV or the HEMS storage battery as opposed to being sold to the local electric power company.

    During the electricity peak time, surplus electricity stored in the HEMS storage battery is supplied back to the house to enable electricity peak shift. These functions require technology to combine electricity supplied back to the home from the EV and commercial power. Moreover, in emergencies such as natural disasters, electricity stored in the EV can be used at home in the same way as the PHV.

The new system was developed in line with the trend toward the standardization of V2H power supply systems. In this demonstration project, DENSO plans to use EVs developed by Toyota Motor Corporation and Mitsubishi Motors Corporation.

DENSO and Toyota [are] working together to develop a V2H power supply system that uses alternating current, and has been conducting demonstration tests using plug-in hybrid vehicles (PHV) to ensure the system can efficiently use energy. With our newly developed system, we will now perform demonstration tests on a V2H power supply system that can be also used for EV.

—Hikaru Sugi, senior executive director of DENSO’s Engineering Research and Development Center and President and CEO of DENSO International America, Inc.

Looking ahead at the next generation of energy and social systems, in 2013 DENSO plans to start demonstration tests in Toyota City to find a way to optimally use home energy using an EV or PHV as the key element, and to develop and commercialize an efficient energy management system to help realize a low-carbon society.



The problem is not daily variation, but annual.
For most of Europe and northern parts of the US this just makes a silly idea more expensive.
Fine if you live in Arizona and points south.


Future long range EVs with 100+ Kwh battery packs will become a major asset for home owners and e-grid operators. Being able to tap in 200+ million EVs (in USA and 10 times more worldwide) with 100+ Kwh battery packs will make a noticeable difference and often will constitute a valuable very low cost 'No-Break' power system.

It is not a silly idea.


Germany's high penetration of PV and consequent noon-time generation peaks could use something like this to absorb the varying electric flows into vehicle batteries and match demand better to the supply.  Doing it with rapid throttling of fossil-fired plants is inefficient.


Doing it with a power source which runs at as low as tenth of summer peak in the depths of winter is even more inefficient.
You wouldn't have to fool around throttling the fossil fuel plants so much if proper baseload had not been displaced by the asinine installation of pv.

Kit P

Wow, how much does this stupid idea cost?

Charging batteries is one of the most inefficient uses of electricity that I can think of. I only store enough to start my ICE.

Matching demand by controlling steam with turbine control valves does not change the efficiency of a power plant. The contribution of solar is not a problem either and I would really be surprised if it is significant enough anyplace in the world.

In California, demand ramped up at a rate of 1000 MWe per hour for about 10,000 MWe when the sun is contributing at it peal production less than 1000 MWe. So you need 10 steam plants with the ability to change output 100 MWe at 10 MWe per hour.



See this report and go to the figure on page 8. Solar and wind are complementary in a Northern European country like Germany. Rainy, cloudy weather with low pressure areas usually comes with strong wind. Long periods of low wind are usually sunnier.

The reason why solar PV makes so much sense everywhere (not just in Arizona) is that it is free energy. Free as in rooftop solar PV occupies no land, has no moving parts, does not require any maintenance and does not suffer the Nimby's. Economically speaking, it is already cheaper than offshore wind, gas peaking plants and will soon be cheaper than onshore wind. Before this decade is out, it will be the cheapest source of electricity.

So give me 1 good reason why we should let all that free sunshine go to waste on asphalt or rooftiles?

Roger Pham

Davemart has good point. H2-storage will be needed with higher penetration of renewable energy.

V2G is still very important for short-term grid energy storage. A BEV has way more battery cyles built in than needed before calender-life limitation, so V2G can put this to good use.


Anne....it is difficult to convince fossil fuel fans that free, clean, renewable energy sources will soon become much better solutions.

We use almost 100% clean hydro (with 2% to 4% wind) and our unique Candu nuclear reactor will be decommissioned within 24 months. Hydro plants can be doubled in the next 20 to 40 years and wind turbines could be multiplied 100+ times in the same time frame.

Our last coal fired power plant and the NG plants were turned off many years ago.

Kit P

“So give me 1 good reason why ”

Sign me up Anne, I want free energy too! Tell me when you will be up on my roof to install those free panels. Be warned that I will have you put in jail for criminal negligence if you do not do a good job and cause a house fire. I also plan to sue you for none performance when you do not deliver power on cold winter nights.

“Before this decade is out, it will be the cheapest source of electricity. ”

The lesson of history repeats itself all the junk producing 'free' will be broken. It twenty more years a new generation will be predicting how things will be will be in ten years.


One thing I'm certain about:  hydrogen will still be the fuel of the future in 2035.  Someone's going to come up with a catalyst that converts CO2 to bicarbonate and back and a membrane that pumps HCO3- across with a bit of voltage, and hydrogen will be stored as a liquid or solid by reduction of carbon as life has been doing for 2 billion years.

Roger Pham

How rude, Kit P!
Anne, you're welcome at my house anytime. And don't worry, I have full umbrella policy insurance coverage in case anything happens to the house or to anyone. And I won't sue anyone since I fully understand that PV panels do not deliver power on any night!!!!

A new arrangement now is that the utility company may own and maintain the roof-mounted PV panels so that the home owners do not have to worry about them at all. The homeowners are given a guaranteed lock-in electricity pricing for the life of the panels, which is a good deal, plus energy security.

And with the low prices of PV panels and still dropping, any bad panel can easily be replaced with new ones. Of course, they are warranted for certain number of years anyway. All suitable parking lots and rooftops should be covered with PV panels!


With 48,000 mega-watts of Hydro in operation and as much remaining to be developed + a 95,000 mega-watt wind potential in the same areas, we do not have to worry about e-power for another 100+ years.

We could increase sales to North-East USA and Ontario if the price is right.


... if you restrict "we" to Quebec.

The average electric consumption of the USA is around 450 GW.


Yes...we is always local or regional. South of the border..
...we means USA ONLY. Nothing wrong with that. We are one of the most power consuming people because e-power is very cheap and we live in a very cold country and most of our houses have not been built to resist cold that well. It will take a few more generations to learn. It is much like smoking tobacco, it took 200+ years for 75% to learn that it is an harmful habit...the other 25% is still resisting.

Individual resistance to change is universal. That's why we had to apply expensive energy saving programs, with great success I must admit. Vermont did very well too. Unlike tobacco, electricity/liquid fuel cannot be banned. Making it more expensive may work? A well design education program could work too.

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