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PowerPack... for home! Why not?

Discussion in 'Tesla Energy' started by tinm, Jun 16, 2015.

  1. tinm

    tinm 2013 S85 Owner

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    The PowerWall is nice but, why not go completely off-grid?

    I'm exploring home solar/battery solutions and after reading all about the PowerWalls, I'm wondering, why not a single PowerPack and some solar panels? I'm burning about 27kWh per day on average (much of that to charge my S!). If the sun were re-upping the PowerPack each day, and I never brought its SOC below say 50%... would that be so bad? What am I missing?

    Other than cost, you say. Well, how expensive would a single PowerPack be? $25K? And what would the minimum solar capacity have to be to keep it charged?

    Ok, donning my kevlar suit. You may begin the onslaught now... :)
     
  2. AudubonB

    AudubonB Mild-mannered Moderator Lord Vetinari*

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    I would love a PowerPack - my battery bank is about the same size (105kWh) but is quite a bit bulkier and cost a heckuvalot more. However, we are over eighty miles from the nearest electrical grid. You-who-live-in-the-real-world might face a zoning code problem of not legally being able to snip your line feed. I would start there - see if you have the right to tell your local provider to do something anatomically impossible with its power. Good luck!
     
  3. tinm

    tinm 2013 S85 Owner

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    Well, assume worst case, that PNM (the powers that be in New Mexico) says, oh no you don't, you gotta stay on our grid if you know what's good for you. So I say, okay, I stay connected to the grid, but my electrical meter sits still forever and my bill is $0.00 per month.

    i wonder if there are any zoning or building codes that would restrict a residence from having 100kW of battery on the premises. I doubt it, but, who knows.
     
  4. ecarfan

    ecarfan Well-Known Member

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    @tin, I had the same thought recently. I would really like to know the cost of a single 100kWh PowerPack. Is it $25K? That much capacity would easily run my small house and charge my Teslas
     
  5. liuping

    liuping Active Member

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    I was thinking the same thing.

    If I'm going to spend the money to get the inverter and Microinverter managment system set up for grid disconnect during power failure, I'd rather get enough battery to last several day or possibly go 100% off grid at some point.

    If my car has an 85kWh pack, it seems reasonable for my house to have a 100kWh pack :)
     
  6. tinm

    tinm 2013 S85 Owner

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    Funny, would've thought more people would chime in here. I was curious how many folks are more interested in the PowerPack for home than the PowerWall. Perhaps partly due to the inspiring off-grid work of the esteemed @wk057.

    Also curious if anyone knows the answers to

    a. price of a single PowerPack
    b. how much solar capacity would be needed to keep the PowerPack at its sweet-spot (90% SOC?), for a house that uses ~27kWh/day.
    c. has anyone actually talked to Tesla about a residential PowerPack?
     
  7. schueppert

    schueppert Member

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    I think you are on to something. Tesla has been successful with its car, in no small part, because the battery is much bigger than the competition. Perhaps even bigger than most people need. And a high price hasn't seemed to matter too much. Maybe they should have taken the same approach with storage?

    Still, I don't think you are going to see a home PowerPack anytime soon. I suspect Tesla is using a higher voltage for its utility product to make it scalable to MWh+ range. Probably 1000V or higher. I'm pretty sure NEC code would not permit this in a residential setting.
     
  8. cantdecide

    cantdecide Member

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    The viability depends greatly on
    1. Where you live... In the bay are you get about half the solar energy in winter that you do in summer. You aren't storing summer energy for winter... So you have to size your system so that it works each month of the year. Depending on your latitude and how your usage varies over the year, you may need to buy twice as many solar panels as you otherwise need to... Or you may not.
    2. Your power company pricing. Mine gives me 30c per kWh for power I sell to them during the say, but they charge me 10c per kWh for what I buy at night... They are a battery that gives me more energy than I put in. Your company may be different.
    Then there are overhead costs that vary. If it would cost $100k to connect your house then sure, spend $25k on batteries and an additional $10k on solar panels.

    So, overall, you'll need to do your own numbers and figure out the benefits of going off grid versus the costs of that wasted solar energy in spring and the battery cost etc...
    For almost everyone it isnt worth it, but you might be one of the few...
     
  9. Tyl

    Tyl Member

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    I just got home my car is on empty, say 2 miles remaining and I want to fully charge it. I'll need 84kWh for the pack and..... I have twin air conditioners here and it's gonna be 111 degrees today. Pool pumps, waterfall pumps, some vacuuming, a load or two of laundry, basic LED lighting for the interior and exterior of the home. There goes another 100kWh. Yes 184kWh in a single day to live comfortably. Say 200kWh. I know that's a lot, but on some days very realistic. Now, solar feeds the power pack, great, but I need a larger system than I currently have so, my guess, a system that produces at least 100kWh/day in the summer....store some... use some....some days us a lot!! I'll need to add sixty panels to my roof. I'm willing to do all that but it does get a little pricey, all to move off the grid. So for the time being, and because it is easy where one can stayed tied to the grid with minimum monthly billing, tied to the grid am I. If the power pack were to drop in price significantly and the price for solar continues to drop as I expect they will, it may indeed be worth it! IMHO as of today, it's on the radar screen.... but it just doesn't make $ense!
     
  10. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Active Member

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    And there are always microgrids, where you'd be _sharing_ a Powerpack with other homes.

    The elephant in the room is the electric car. In order for Tesla's model to work well with microgrids, they'd really have to have a dense Supercharger network.
     
  11. Tyl

    Tyl Member

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    #11 Tyl, Jun 17, 2015
    Last edited: Jun 17, 2015
    Let's use solar and power packs here instead. Example. Navajo Generating Station is a 2250 megawatt coal-fired powerplant located on the Navajo Indian Reservation, near Page, Arizona, United States. The number of solar panels and power packs needed to produce 2500+megawatts at just this one station to completely make it renewable, will bring the price of solar and power packs down!! Arizona owns the sun and you'd think this would be the easiest of switchovers on the planet!! Multiply that by many many old nasty coal fired generating stations and we will be on the way to really making a difference in global CO2 levels, not to mention cleaning up the horrific toxic mess done to the earth over all these years. The time is now!! ..... Wow!! I'd love to see a 3000 to 4000 megawatt solar farm! That number would provide a little cushion for the future too. ..... and again....ARIZONA HAS THE SUN TO DO IT!!!!!!!!!
     
  12. ecarfan

    ecarfan Well-Known Member

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    Good point, I hadn't thought of that. Oh well, guess I will have to string PowerWalls together.
     
  13. Robert.Boston

    Robert.Boston Model S VIN P01536

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    My guess is that the PowerPack is either at 480v, matching the top voltage usually found in commercial properties, or 13kV, matching the normal distribution voltage in the U.S. If it's 480v, that might be okay in residential settings; I'll defer to experts on the NEC.

    Re panel sizing, if you're truly going to go off-grid, then you need to do some really careful studies about solar insolation at your location, and do some hard thinking about your minimum required usage. What do you turn off after 2 cloudy days? After 4? How likely are those back-to-back "solar outages"? You cannot look at averages, but instead at the outlier events.

    If you're in striking distance to a Supercharger, you at least have a way of exporting some of your demand.

    - - - Updated - - -

    My guess is that the maximum scale of the PowerWall strings won't be enough to take you off-grid.
     
  14. AudubonB

    AudubonB Mild-mannered Moderator Lord Vetinari*

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    To add on to Robert's good suggestions. I can offer that in our situation, where we are 80 miles and millions of dollars of infrastructure from the grid, we maintain a full-sized generator as a back-up to our PV+ battery system. It is a 30kW diesel genset - I used to have a propane generator but that showed itself to be inappropriate for our arctic winter temperatures - and it has proved to be a good alternative to the onerous pricing needed to have a PV & battery system large enough to take care of those times when it rains for our days straight or during the depths of our winter darkness when we also (a rare occurrence) have large electrical consumption.

    This solution is a compromise: you maintain reliance on hydrocarbons, but after five years on same I can report that our diesel consumption in that time has totaled slightly less than 250 gallons, which truly is small beer.
     
  15. Evbwcaer

    Evbwcaer Member

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    I recently looked at the possibility of a wood fire heated TEG generator setup. It looks like it could be fairly straightforward to make a 1000w generator that could also heat your house, powered by wood. I got the idea from the crazy buckthorn infestation in my area, thinking I could charge my car and heat my house with invasive buckthorn. There are also wood gas generators and you could run a diesel genset, as mentioned, on waste vegetable oil or biodiesel. In the winter you could run this nearly non-stop, making something like 20kwh/day and heating your house.

    I have and love solar because it is so simple and easy, but as others have said it may make more sense to have some solar and then another way to make electricity as well to deal with bad weather or peak need if you are off grid.

    http://www.thermonamic.com/TEG500WEnglish.pdf
     
  16. Chris TX

    Chris TX Active Member

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    I plan on getting a PowerPack for my new house, unless there's some crazy restriction that prevents me from getting one. If I had an existing solar setup, I might get a PowerWall or two in my current house.
     
  17. dhanson865

    dhanson865 Active Member

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    #17 dhanson865, Jun 21, 2015
    Last edited: Jun 21, 2015
    Well I don't know about your public utility but mine charges me $14 a month for a 0 kWh bill.

    So even if you gave me the exact number of solar panels to cover my usage and a PowerPack (or 9 powerwalls), I'd have to sell power back to the grid at least enough to offset that $14 or I'm paying from my checking account.

    I could definitely cut the power from the grid. I don't know if I'd have to have a lawyer to fight it if a neighbor or coworker got mad at me and tried to have my house condemned for not having grid power.

    Avondale condemns home: Solar, batteries insufficient

    She had 6 PV panels and 8 batteries for one person. They said it wasn't enough for proper quality of life. If they can do it to someone who might be somewhat down on their luck I'm not going to trust the system enough to push the issue and waste money on attorney fees just to try and save $14 a month.

    Maybe the same bureaucratic system would consider it insufficient even if you had dozens of PV panels and a powerpack. No matter that you have a $100,000 car, a heated pool, two central AC units purring away. Maybe they want to be jerks and say you have to be on the grid.
     
  18. gavine

    gavine Petrol Head turned EV Enthusiast

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    Doesn't need to be a supercharger. In a pinch, an HPWC destination charger or J1772 would help too.
     
  19. EchoDelta

    EchoDelta Member

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    Impressed.. Have you had any such 200kWh days, ever?

    - - - Updated - - -

    How does one even start the conversation about a powerpack for multiple residences? I am contributing to an 18-family farm-residential project, and this would make sense. Any pointers from those here to an effective point of contact?
     
  20. Tyl

    Tyl Member

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    I've never had a 200 kWh day, close but not yet. If I add an MX soon to the family fleet it could happen. Arriving home with both vehicles empty, the fridge is running intermittently through out the day. Pool pumps? Waterfall pumps? Laundry/tumble dry? Toaster? Dishwasher? Vacuum? LED lighting? Landscape lighting?

    I've spoken to Solar City about the above. Arrrgh... My utility is no longer grid tying new solar panels due to ???? So I asked about adding more panels and to add a future power pack so I could go DC to DC to charge the MS/&X. I'm trying to let them see future home power needs! We'll see! Today the PP are not available for home use. I'd have to have a garage full of powerwall to make it work (somehow)!!!!! ...but 'soon' :rolleyes:
     

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