V2Grid, V2Business, V2Home ?

V2Grid, V2Business, V2Home ?

Are the Teslas capable of bi-directional power flow.
If not are there any plans to make this happen.

negarholger | 21 août 2013

Pulling energy out of the battery is a silly idea... owners will not sign up for that. Much better aproach is to use charging as variable load - same effect. Yes TM is working in that direction.

Technically it is possible to make it bidirectional, because the direct DC connection available in the charging port. The needed electronics however would be outside the car.

vadik | 21 août 2013

It is not a silly idea if you have eg a log cabin in the mountains.

Kleist does not own a log cabin in the mountains.

Charles G. | 21 août 2013

It might bring a value proposition to Tesla in that the Utilities pay a premium for peaker plants that only work a small percentage of the time.

I could see hooking up to V2G if one could get paid a feed in rate that equals around $200.00 or more pr/mth.

$200.00 feed in + $300.00 in gas savings = $500.00 pr/Month to my bottom line.

Ill bet that the way these batteries are designed, that it would have a negligable effect on service life.

It could also be engineered to leave plenty of power in battery for my commute home as most load leveling is done while peaple are at work during the day.

I really dont think its a silly idea I think it needs to be seriously studied as this could have the potential to make wind solar much more viable.

negarholger | 21 août 2013

No I don't own a log cabin in the mountains.
- Pull the energy out of your battery and stay forever at your cabin?
- how big is the log cabin market ?
- the thread is about log cabins ?

bent | 21 août 2013

There is something to be said for using people's EV battery pack for domestic power in general, allowing utilities to balance out the grid by pulling or pushing power around according to demand.

But for this to really be practical battery pack prices need to come down a whole lot, people won't be happy for the gratuitous wear on their $30k+ packs.

vadik | 21 août 2013

Kleist - the thread is about log cabins ?


No, it is about biderectional power flow and your crippled capability to transcend your own limited and ill lit field of experiences. Poor vision, lack of imagination, narrowsightedness and wooden cogwheels in your thinking apparatus is no reason to kill somebody's fairly plausible and easy to implement idea.

vadik | 21 août 2013


PorfirioR | 21 août 2013

You may want to talk to SolarCity, not Tesla:

I seem to remember this being brought up before and someone making an excellent point that by designing ways to allow electricity to flow out might create safety concerns for rescue personnel, etc. It sounded like a good enough reason to me, even if it is a remote possibility.

IMHO, adding bidirectional power flow capability does nothing to make the car perform its transportation function any better, yet there is a greater than zero probability that it would reduce safety.

nwdiver93 | 21 août 2013

IMO this is one of those not "if" but "when" things. Tesla is probably apprehensive about V2G in the short term because the public is going to judge battery life in terms of "Miles" and not "kWh" so if you drive 15000 miles/yr but you're pulling 20 kWh off your battery every day to sell back to the grid your battery degradation will appear significantly higher than it actually is.

Once EVs gain mainstream acceptance and cycle life improves it's inevitable that consumers will demand the ability to store power when it's cheap and sell it back when it's more expensive.

The Balance of System cost of solar will likely drop below $1/w by 2020. By 2030 there is a very high probability that curtailment of PV during some hours will be required. The ability to use EVs as storage is critical if renewables are to comprise a significant percentage of power consumption.

Before V2G we will have "On Demand Charging". I spoke to a utility rep at TESLIVE; there is already an app in development that would allow EVs owners to be paid for the ability of a utility to control the charging of their cars as a way to "dump" excess generation (when fuel is free and demand is low i.e. wind power). It's not bi-directional yet... probably not for another ~10 years.

negarholger | 21 août 2013

@vadik - feisty, feisty...

You wouldn't buy a race horse to haul logs. Oh when you need it to haul logs the horse is actually racing.

The idea of using EV for grid is many, many years old, but people moved beyond that. Reasons:
- when you need it most ( afternoons ) cars are not plugged in typically
- the Leaf comes home, house A/C humming, battery empty
- the availability of the resource is not predictable
- unpredictability is a safety hazard

Much better solution is
- use the EV as a variable load only, has the same effect
- batteries at super charger will do a much better job at grid leveling
- at home a small stationary battery (~8 kWh) is a much better solution for peak load leveling and power out bridging. And this battery doesn't need to be designed like a race horse, but like a work horse.
- stationary batteries are predictable and more safe.

For the isolated log house in the mountain it would be a nice solution only the market is just to small to engage in. All mountain houses I've been in had electricity, many actually washer and dryer.

RanjitC | 21 août 2013

My solarcity rep told me they are selling a smaller battery as backup power, and that tesla dissuades us from using the car battery for backup power. Maybe even voiding the warranty. This is hearsay not to be accepted in a court of law.

negarholger | 21 août 2013

Yes, the utilities are starting to complain... the usage peak and the solar production peak are offset - a small battery would allow you to shift solar electricity for a couple of hours. Look at Germany - when the sun shines and the wind blows they don't know what to do with the electricity. For renewable engery storage is key to be effective.

Brian H | 21 août 2013

Backup in case of brownouts or blackouts, including the ones imposed by utilities utilizing the Smart Grid to minimize their generation requirements. >:P

vadik | 22 août 2013

Kleist - at home a small stationary battery (~8 kWh) is a much better solution for peak load leveling


Aha, so given the need for a particular person is there, instead of incorporating a one-dollar-material-cost-thingy into Tesla you you propose to buy a thousand-dollar-space-and-time-taking device.

You are diconnected from rational reality.

negarholger | 22 août 2013

Bi-directional capability "a one-dollar-material-cost-thingy " - if that is your perception then the model S car should sell for $20 to $200. Dream on.

vadik | 22 août 2013

How much should a foot of copper wire cost?

If there were no flux of electricity out of the battery the car would not move.

negarholger | 22 août 2013

The Leaf solution costs $4,200, but only announced for Japan where the average household uses one third of the electricity of the average US household. I just had an adequate 6 kW inverter quoted for my house - a touch under $10k. So I would expect a mass produced factory installed version to be around $3k-$5k minimum. Retrofit $10k-$15k, external version $5k-$10k...
A piece of wire is not doing the trick.

vadik | 22 août 2013

First, there is a difference between price and cost, second, if a leader in BEV such as Leaf HAS such a solution that it CANNOT BE that stupid an idea.

Now multiply it by number of log cabins in Japan.

erici | 22 août 2013

I would love bi-directional Model S.

I am in Montecito, CA with Southern California Edison for my power company. The sell me electricity for 9 cents per kWh at night between midnight and 6 am, then they charge me 47 cents per kWh between 10am and 6pm.

With net metering, I could zero out my energy bill rather easily :-)

erici | 22 août 2013

The BYD e6 car has bi-directional charging and discharging. The rest of the car is not as cool as the Model S.

But that feature alone lowers the cost of ownership -- for me at least, given that I buy electricity for 9 cents and sell it for 47 cents. That's a nice spread of 38 cents profit, should be more than enough to offset the battery wear.

Helps pay for the larger range batter pack -- make use of it every single day instead of just for the long range trips. Very practical.

vadik | 22 août 2013

erici, do you have a log cabin in the mountains?

nwdiver93 | 22 août 2013

Only a matter of time... probably have some after-market stuff available in ~7 years... when the first MS batteries are out of warranty and MS owners don't have to worry about voiding it.

My Grid-Tie inverter takes ~300-480 VDC; The MS battery is ~360VDC depending on SOC so if I REALLY wanted to I could feed my battery back to the grid but I'd probably have to do a little prying and warranty voiding.

Brian H | 22 août 2013

No, he lives in one in the 'burbs. <8)

erici | 22 août 2013

No log cabin anywhere :-) I do want one though.

Let's say my average is 27 cents per kWh (it is) and let's say I use 36 kWh per day excluding my EV charging (I do).

So the real savings (based on a 30 day month) is:
36*30*.18= $194.

So I would save $194 per month if I could purchase all of my electricity for 9 cents per kWh.

That's $2,328 per year in energy savings. After eight years, I've got $18,624 saved on home electric bill to put towards purchase of a replacement battery.

They charge $12,000 (paid upfront today) for an 85 kWh battery replacement:

So, sure it might void the warranty, But then again it's enough money to purchase a replacement battery in 8 years and to also have a nice profit of $6,624 on top of that.

erici | 22 août 2013

But anyhow, I would only need to discharge 17 kWh from my battery pack into the grid to fully offset my bill (because I get paid at the 47 cent rate between 10am and 6pm instead of the average cost of 27 cents).

The car is normally home during those hours. It's an 85kWh battery -- if you take 17 kWh from it I still have good range.

ChrisPDX | 22 août 2013

In the warranty guide, it even mentions this as one of the items not covered under warranty:
Using the vehicle as a stationary power source;

So at this time, even if you could get the car to output power, you would most likely void the battery warranty if TM found out.

erici | 22 août 2013

Well, I suppose I could just completely wipe out the bill via net metering instead of just bringing my cost down to 9 cents per kWh.

I would save $291 per month by zeroing out the charge for electric usage.

Hmmm... I would need to sell 25.5kWh from my battery every day at 47 cent peak rate.

That still leaves me with 60kWh of battery capacity per day for driving!

In 8 years it generates $28,000 worth of utility bill savings.

Okay, this solves the problem of the battery becoming worthless over the years!

But look, how cheap would it be to lease this car if you could reduce your household electric bill by $291 per month! Of course, you would also be able to drive the car for free (given that you can just sell even more energy into the grid to recover the cost of charging the battery).

What's not to like? I completely don't understand why people don't want this feature.

negarholger | 22 août 2013

- my electricity bill is $70-$100 a month ( w/o solar )
- spread is $0.16
- high rate is when the car is not home.

And btw there is no pre paid battery option, I was announced but not ever actually offered.

@ChrisPDX - Tesla already knows... discharging at home location, car not moving.

erici | 22 août 2013


Kleist sees no need for it because he doesn't benefit from it.
I see a need for it because I benefit from it.

Human nature. People vote for what is good for them. Both of us included.

vadik | 22 août 2013

Yeah, and then when people vote for smth they vote against they call them dirty sexually unattractive imbeciles.

negarholger | 22 août 2013

@erici - Aha ! You have an option... BYD e6 has everything you need. So what is the whining about? Get one.

erici | 22 août 2013

You get more bees with honey Kleist.

negarholger | 22 août 2013

That was the honey

erici | 22 août 2013

Well there you go, now I've misquoted. Well, evidence that it's been too long of a day.

Brian H | 22 août 2013

Yeah, it's flies that you get. After robbing the honey from the bees.

ItsNotAboutTheMoney | 23 août 2013

The fundamental problem I see with V2X on a large scale is that if lossy charging and discharging a battery becomes economically advantageous the suppliers and utilities will be able to do it better themselves.

I agree with Kleist's view that PEVs will be a valuable demand sink, rather than a grid storage medium.

CalDreamin | 24 août 2013

The training video that Tesla did for first responders says the Model S cannot send power backwards through the charging port.

I'd like to have a 110V 20A outlet on the Model S. My Toyota pickup has a 110V outlet, though it's less than 20A.