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Vehicle 2 Grid yet again

Discussion in 'TSLA Investor Discussions' started by mrmage, Jul 12, 2019.

  1. mrmage

    mrmage Member

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    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.
     
  2. mrmage

    mrmage Member

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    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.
     
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  3. ggr

    ggr Roadster R80 537, SigS P85 29, M3P 80k

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    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."
     
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  4. Flyguy

    Flyguy Member

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    #24 Flyguy, Jul 12, 2019
    Last edited: Jul 12, 2019
    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.
     
  5. mongo

    mongo Well-Known Member

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    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.
     
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  6. MP3Mike

    MP3Mike Well-Known Member

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

    mrmage Member

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    #27 mrmage, Jul 12, 2019
    Last edited: Jul 12, 2019
    $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.
     
  8. Flyguy

    Flyguy Member

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    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
     
  9. MP3Mike

    MP3Mike Well-Known Member

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    #29 MP3Mike, Jul 12, 2019
    Last edited: Jul 12, 2019
    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...
     
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  10. mrmage

    mrmage Member

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

    Flyguy Member

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  12. mongo

    mongo Well-Known Member

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    PW is ~48V internal, vehicle pack is 350V-400V.
     
  13. MP3Mike

    MP3Mike Well-Known Member

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    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.)
     
  14. MP3Mike

    MP3Mike Well-Known Member

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    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.)
     
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  15. MSDadMich

    MSDadMich Member

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    Way too many assumptions here
     
  16. bxr140

    bxr140 Active Member

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    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?
     
  17. mrmage

    mrmage Member

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    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.
     
  18. Sudre

    Sudre Member

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    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.
     
  19. tomsax

    tomsax Member

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    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:

    V2G-Owner-Costs.png

    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.
     
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