EV to grid technology in our future?

by Ernie Hernandez on October 4, 2011

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Use your EV to power your house

We have written about this before. Your electric vehicle (EV) – be it LEAF, Mitsubishi i, or whatever else happens to pop up down the road, can potentially be used to provide power for you and your family in an electrical blackout similar to what the entire county of San Diego endured recently.

The University of Delaware, working with  NRG, a northeastern United States power provider, has announced a partnership to further the use of electric vehicles to stabilize electric grid power. With a (potentially) vast pool of electric vehicles available, electricity distribution management can become more convenient, and more efficient than ever before. Let’s take a look at an example.

Let’s say that a company is operating a fleet of electric vehicles. At any given time, some of these fleet vehicles may not be needed in service. Rather than just sitting idly in the parking facility, these vehicles can be connected to the smart grid, providing their charging status and availability to the grid to provide power. The EV fleet operator determines the requirements of the vehicle. If certain vehicles need a certain charge to complete upcoming commitments, their power is not accessed. Those vehicles not needed in the immediate future can provide power back to the grid up to the point defined by the fleet owner. Ultimately, consumers will also be able to benefit by selling back power to the grid during peak usage while charging during off-peak time frames. Ultimately, this translates into the ability to make money from your car, as you charge at low off-peak rates, and sell power back to the utility at higher on-peak rates. Naturally, not everyone will be able to do this on a regular basis, but certainly some EV owners will. As opposed to all of those naysayers that project the EV as the scourge of the power grid, this EV to grid technology can be seen as a boon to the entire utility industry as EVs reach a greater adoption rate.

Look for more information coming your way soon on this topic, as much has been written lately that we wish to pass along.

{ 6 comments… read them below or add one }

indyflick October 5, 2011 at 8:30 am

I would certainly want to be able to power my home with my LEAF during a blackout. However, I would never allow my LEAF to be used to provide power back to the grid on a regular basis. Doing so just adds unnecessary wear and tear on a very expensive lithium-ion battery pack. Which means it will fail much sooner and cost me a bundle to replace. If you have your heart set on connecting batteries to the grid, then buy a stack of much much much cheaper lead acid deep-cycle batteries. You’ll be money ahead in the long run.


Sasparilla October 5, 2011 at 11:08 am

Indy is right on target here. Use your Leaf instead of portable generator in the event of a power outage – you bet.

Use that more than $10k battery pack with expected capacity loss issues due to cycle life in a scheme to put more power on the grid when needed is just ivory tower day dreaming at this point. The idea is very useful and cool, but it makes no sense considering how expensive those packs are.

Current Lithium battery technology has cycle capacity issues and isn’t up for this, from what I can tell the next generation packs (Leaf 2 or Volt 2) will still have this issue. Maybe in a few generations science will solve the Li cycle capacity issues and make this a feasible idea (car to grid power transfers).

There’s a little irony that the previous rechargeable battery technology, NiMH, when managed properly – would work just fine with the car to grid idea – although it doesn’t have near the capacity of Li packs. NiMH when cycled between certain top and bottom capacity levels (its like 20% and 70% or something) has almost no effect on pack capacity over time – this is why the NiMH packs in Prius’s last so long as Toyota keeps it in this range for normal use). So an old EV1 NiMH (if GM hadn’t destroyed them all) or Rav4EV NiMH, if charge levels were kept in the proper range, would work great for car 2 grid.


Ernie Hernandez (LEAFguy) October 5, 2011 at 5:28 pm

Thanks for the input guys.

I’m no electrical engineer, so I’m just writing about some of the technology that is being presented. It stands to reason, though, that you would not want to degrade your vehicle battery pack unnecessarily. Perhaps for emergency power, it might make sense as that need would be infrequent and likely short lived.


Gwido October 6, 2011 at 5:13 am

It all depends on how much the utility companies are willing to pay in order to use the battery for grid stabilization.
Let’s say the LEAF’s 24 kWh pack cost 10 000 $ to replace and is good for 1000 cycles before it’s capacity diminishes under 70-80% (some numbers I read recently). That means the cost of using the battery is around 10,000$ / 24*1000 = 42¢ / kWh.
Of course, there are other factors. Using some of the pack capacity in the middle of it’s SOC (near 50% charge) should result in less wear than using it near the bottom of top of it. But if the utility is willing to pay you that rate (and I have no idea if they would), then I don’t see any reason not to participate. If you don’t drive a lot, you may as well take advantage of your battery before it loses capacity due to its age.


indyflick October 6, 2011 at 9:45 am

$10,000 is Nissan’s cost for the pack, not the price to a customer. In addition, there would be installation costs. On top of that is the reduced range of the LEAF which would occur sooner as a result of the V2G application. However, once the pack has depleted to say 70% – 80% of its original capacity, perhaps then it might make sense to remove those batteries from the LEAF and use them to feed the grid. With a BMS they may last another 10 to 15 years in that application. After that they could be recycled.


Ron Solberg October 5, 2011 at 8:05 pm

Twice in the 1980s I fed the grid with a WEC (Wind Electric Conversion). The first was a 10 Kw Jacobs. It was fun to watch the meter spin backwards. The second was a 4 kw Whirlwind. While the law allowed me to do this, the power company’s roadblock caused me to go stand-alone using 20 golf cart batteries with a 1949 3 Kw Jacobs and 3 Kw tracking solar PV. A 500 pound gorrilla sits whereever it wants. The power company raised the issue of safety for the lineman, wanted expensive insurance and wanted to enter my home 24/7. Recently they called us to join their “Second Nature” program where I agree to pay a higher rate to support the “giant” WEC program. When I said yes, if they would work with me to connect my small WEC to the grid, it got quiet at the other end of the line, the person talked to someone and gave me a number tp call if I wanted to try a third time to work with the power company. To add to the problem, in recent years my power company was bought out by a larger company making them even harder to work with. Now they don’t even try to be a good neighbor. Based on this experience alone, I feel that unless our social fabric undergoes marked change, an EV to grid connection has little chance.


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