Vehicle 2 Grid yet again

[mrmage]

I didn’t realize this was covered before. But for context, my primary need is just as battery backup for a few days if power goes out. That wouldn’t degrade batteries because it would be rarely used.

For context, our utilities company PG&E sent a letter telling customers to expect outages during fire season. One of the options they suggessted was a generator. They service 5M customers, but there must be many other customers who have occasional outages.

If it isn’t overly expensive, an option to provide V2H (not necessarily V2G) would be very attractive.

 

[mrmage]

Isn't battery backup for the home more complicated than just enabling V2G in the car? It seems that any customer wanting to use their vehicle as home battery backup in case of grid failure would need some sort of isolation cutoff installed so that they're not energizing the grid with their car during a power outage.

Yes, absolutely. That’s why powerwall installation requires an electrician. That’s required in either case. And an inverter is required for E2H.

I just don’t want a separate set of batteries for $50,000 when I already have 100k kwh of them sitting in my garage.

 

[ggr]

Here in SoCal I worry about the scenario that power goes off (because of wildfire or earthquake or mudslide or whatever) and when I go to evacuate I have only enough charge for 10 miles. My car battery is for driving my car.

Smart management of charging makes some sense to me, but I would still want a way to say "charge now, I really mean it."

 

[Flyguy]

Like others, I also would like an V2H option for the few times a year the power goes out. I’ve priced a two Powerwall system and even with incentives the value is not quite there. We are on solar and usually break even at true-up time so there is no financial gain for storing energy. The switch for the Powerwall is $1,100. If they made a similar switch for my car I would gladly pay that fee plus sub panel installation to use my car as backup when needed. What I don’t know is how much the inverter would be. Assuming the whole system was $3-$4k I would consider it.

 

[mongo]

Like others, I also would like an V2H option for the few times a year the power goes out. I’ve priced a two Powerwall system and even with incentives the value is not quite there. We are on solar and usually break even at true-up time so there is no financial gain for storing energy. The switch for the Powerwall is $1,100. If they made a similar switch for my car I would gladly pay that fee plus installation to use my car as backup when needed.

The problem is that, in addition to the $1,100 automatic disconnect, you would need a large inverter to turn the car's DC pack voltage to AC.

On the other hand, the inverter could be designed to be used as a higher power charger than the car itself has.

 

[MP3Mike]

The switch for the Powerwall is $1,100. If they made a similar switch for my car I would gladly pay that fee plus installation to use my car as backup when needed.

You would need an inverter as well which would add another $3-6k.

 

[mrmage]

You would need an inverter as well which would add another $3-6k.

$5k for an inverter, $1k for disconnect switch and $1-2k for installation.

With that, I power the house for a week with the MX in the event of a disaster and for shorter outages when the Tesla is in the garage. Sure beats installing a half dozen Powerwalls.

Tesla has the expertise and most the design done. The effort is small, but it's a big selling point even if someone doesn't buy it right away.

If one car has this option, and the other doesn't, it's a big selling point for the car that does. Kind of like good FUD.

 

[Flyguy]

You would need an inverter as well which would add another $3-6k.

Every Powerwall has a built in inverter, so that price range does not make sense to me. 3k seems high, but 6k is almost the cost of the Powerwall itself

 

[MP3Mike]

Every Powerwall has a built in inverter, so that price range does not make sense to me. 3k seems high, but 6k is almost the cost of the Powerwall itself

Each Powerwall has an inverter. And you need at least two to power most homes.

Show me an inverter big enough to power your home for less...

 

[mrmage]

Every Powerwall has a built in inverter, so that price range does not make sense to me. 3k seems high, but 6k is almost the cost of the Powerwall itself

Would be great to have this built into the Powerall. Or a Powerwall with a connector to the car instead of batteries.

 

[Flyguy]

Each Powerwall has an inverter. And you need at least two to power most homes.

Show me an inverter big enough to power your home for less...

Google Image Result for https://media.giphy.com/media/hAogM2NqtbBF6/giphy.gif

 

[mongo]

Would be great to have this built into the Powerall. Or a Powerwall with a connector to the car instead of batteries.

PW is ~48V internal, vehicle pack is 350V-400V.

 

[MP3Mike]

Would be great to have this built into the Powerall.

Yeah, we actually expected this back when the solar roof and the Powerwall were announced. They had mentioned a charging component. But it never materialized. (But it could have just been a quick DC charging of the car, not a bi-directional connection.)

 

[MP3Mike]

PW is ~48V internal, vehicle pack is 350V-400V.

When they announced the Powerwall 2 there was an AC and a DC version. The DC version had a ~50 volt internal battery but had a 350-550 DC-DC converter in it instead of an inverter. That would have worked great paired with a car. (Of course they never actually made the DC version, but I still have the data sheet.)

 

[MSDadMich]

The battery will almost always be used to its full cycling potential (barring the premature loss of the vehicle in an accident) - V2G or no V2G. No potential is being wasted. What strikes me as dumb is preemptively aging the battery pack, which will bare minimum require a battery replacement, and would usually cause a whole car to get thrown away years earlier than it otherwise wouldn't have been (since most people probably won't do a battery swap on an old car). What also strikes me as dumb is dedicating cycles of cells focused on energy density to a task that would be better suited to cycles of cells focused on longevity and cost.

Cell cycle lives are finite. You can't get around this. If you allocate a cycle to one thing (e.g. V2G) then you're not allocating it to something else (like driving). You make more cycles by making more cells. Do you want said more cells/cycles to be ones focused on longevity and cost, and installed where they'll do the most good, and always connected to the grid when the grid will need them? Or do you want said cells/cycles to be focused on energy density instead, and always in a car, which may or may not be connected to the grid at a location where they may or may not be needed?

A much better option is smart charging. Like V2G, but without actually outputting power. You tell the car how much of a charge you want and when you want it, and it decides - based on grid rates, reflecting grid needs - when to actually do said charging. Smart charging doesn't impose any extra cycles on your battery pack, but it keeps vehicles from charging (unless owner needs demand it) when the grid is stressed. It of course, like V2G, requires a smart grid which can transmit power needs and forecasts.

Way too many assumptions here

 

[bxr140]

I'm sure any company will love to have their electricity paid for from the employees' home electric bill.

There's obvious management infrastructure that needs to be implemented for any of the V2X use cases. A mutually beneficial financial structure is self-evident as necessary in the case of V2Work.

Mind, IMHO V2Work is probably not the most efficient concept for exchanging stored energy, but who knows what kind of discoveries will come out of a study and small scale implementation? What's the harm in pursuing it?

 

[mrmage]

When they announced the Powerwall 2 there was an AC and a DC version. The DC version had a ~50 volt internal battery but had a 350-550 DC-DC converter in it instead of an inverter. That would have worked great paired with a car. (Of course they never actually made the DC version, but I still have the data sheet.)

Maybe it's still coming. A feature like this helps other OEMs differentiate their EVs from Tesla. Spending $1M to engineer a V2H option would be a drop in the bucket if an extra 1% of Tesla sales were diverted to an OEM. For a change, Tesla would need to catch up to the other EVs.

Otoh, spending $1M to add V2H to Teslas would easily be paid back if only 1% more Teslas were sold over ICE. This feature doesn't take away from their battery capacity either.

 

[Sudre]

I do like the sounds of a Tesla type Powerwall/charger that charges my car and I can set it up to provide power by using the car's battery down to a certain percentage I can set.

I think the issue would be with the average Joe keeping his house running during a distant forest fire (or any natural disaster) then having the fire department knock on his door and tell him he has to evacuate with a 10% battery. How about an automatic setting (on as factory default) to stop using the cars battery when it gets down to the range needed (+20%) to get to an operational supercharger where the owner then pays to recharge.

If the Powerwall is doing all the heavy lifting the cost would mainly be incorporated into the Powercharger not the car. The Powercharger could also monitor the house usage and in times of fast charge needs it could charge at max amps of your main breaker -20% -house usage. Just press the fast charge button. This special charger would have no batteries of it's own but could be linked with Powerwalls. 400 amp service... just watching TV on a 70 degree day.... Charge at 70kW!

Yes everyone knows using a battery degrades the battery sooner. Tesla could have an augmented battery warranty people have to sign if they felt it was an issue.

Just my 2 cents.

 

[tomsax]

In 2015, I used data from the Plug In America EV Battery Surveys to calculate battery pack capacity loss per kWh cycled through the pack from the LEAF, Roadster, Model S 60 kWh and Model S 85 kWh. I then modeled the depreciation cost of each kWh based on battery pack replacement costs and assuming the pack gets replaced at either 80% or 70% of original capacity. Here are the results:

From this, we see that a Model X 85 owner participating in V2G and willing to wait until the pack is down to 70% would have to be paid around $0.17 per kWh hour to break even, or $0.28 per kWh if wanting a new pack at 80% of original capacity. Obviously, an owner is going to want to do better than just break even to participate in something that reduces range and hastens pack replacement.

So, at least according to my analysis of the survey data in 2015, V2G power is pretty expensive.

 

[Stars aligned]

In 2015, I used data from the Plug In America EV Battery Surveys to calculate battery pack capacity loss per kWh cycled through the pack from the LEAF, Roadster, Model S 60 kWh and Model S 85 kWh. I then modeled the depreciation cost of each kWh based on battery pack replacement costs and assuming the pack gets replaced at either 80% or 70% of original capacity. Here are the results:

View attachment 429629

From this, we see that a Model X 85 owner participating in V2G and willing to wait until the pack is down to 70% would have to be paid around $0.17 per kWh hour to break even, or $0.28 per kWh if wanting a new pack at 80% of original capacity. Obviously, an owner is going to want to do better than just break even to participate in something that reduces range and hastens pack replacement.

So, at least according to my analysis of the survey data in 2015, V2G power is pretty expensive.

This will change when this "million miles battery" comes. Hope to see more during the battery event later this year.

I can see the following use case, for example: 3 cars in a 2 person household (we have 4) for different purposes. Daily commuter, pickup and a convertible sports car, for instance. Solar charges at home, and solar might even charge at work in the future when solar cells become mandatory on new buildings. We commute roughly 100km a day, so our Model S is way oversized for a typical commuting day.

Plenty of battery capacity to power a household can be stored this way. Battery wear will be almost insignificant with new technology. And I'm not willing to leave a Roadster of Pickup do Robotaxi services, probably not even a Model S / 3.

External inverters make a lot of sense in this scenario. Tesla should offer V2G solutions when new battery technology is available.