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2 Powerwalls for whole-house backup

Discussion in 'Tesla Energy' started by Dan123, Jun 19, 2018.

  1. Dan123

    Dan123 Member

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    Has anyone used 2 PWs for doing a whole-house backup?

    I am installing solar panels, and the installer is not very knowledgeable about PW. They are not yet available is South Florida.

    Is it really as simple as connecting two PWs in parralel to the main electrical panel, and installing a gateway between the meter and the electrical panel?
     
  2. Ejl80

    Ejl80 Supporting Member

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    I have an order for two powerwalls. The wiring is as follows according to Tesla’s diagrams.

    Utility power to gate way.

    Two powerwalls to a sub panel. This sub panel to gate way

    Gateway to main electrical panel.

    Solar comes in at the main electrical panel.

    I am having it set up for backup only and charge from solar only.
     
  3. Baja30

    Baja30 Member

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    I don't think Tesla lets you DIY.
     
  4. Dan123

    Dan123 Member

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    I understand that Tesla doesn’t let me DYI. But I need to install a solar system in a way that is going to be compatible with future PW installation. And I need to know if the whole-house backup is doable with 2 PWs. This affects the design of the current solar system.
     
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  5. cwied

    cwied Member

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    This is what Tesla did for my whole-house, dual Powerwall installation:
    [​IMG]

    From left to right: generation panel, load panel, Tesla Gateway, main panel.

    They moved all my load breakers from the main panel to the load panel. The main panel now only has one 200 amp breaker that goes to the gateway.

    The generation panel takes in from my solar and from the batteries. It feeds the gateway.

    The load panel gets fed by the gateway.

    In case the picture doesn't work on TMC: https://photos.app.goo.gl/BNbZuEQZfWc1Da3S9
     
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  6. arnolddeleon

    arnolddeleon Supporting Member

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    I have whole house backup with 2 Powerwall 2s. If you have an EV charging stations consider not putting them behind the backup. A car charging overnight will empty the Powerwalls quickly. Right now you have do some of your own automation to stop a car charging if the power goes out.
     
  7. Babaron

    Babaron Member

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    Interesting info. So what is the recommended way to set up ev charging when solar and power walls are planned?
     
  8. electracity

    electracity Active Member

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    Use a solar company that installs powerwalls. Tell them you want to prewire for future powerwalls.

    How you isolate an EV charger will depend upon how load control is done in your particular house. One way is a sub panel that also isolates AC compressors that if energized would exceed the total load rating of the powerwalls.
     
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  9. Dan123

    Dan123 Member

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    Interesting, thank you.

    Do you know when they moved everything from the main panel to a new panel? Why couldn't they use the old panel? I understand that the power from the meter goes into the right-most main panel that now doesn't have any breakers.

    What's the purpose of "generator panel?" there is a tube that goes up, what does it feed? Or do they connect with the "gateway" above the picture frame?
     
  10. Dan123

    Dan123 Member

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    And what are the two tubes going up to the load panel? What do they connect to? And what does tube on top of the gateway connect to?
     
  11. wwhitney

    wwhitney Member

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    See pages 8 and 9 of the Powerwall Owner's Manual Tesla

    With whole house backup, the backup gateway has to be inline between the power company (meter) and all the loads of the house. If you have a "meter main" or "all-in-one" panel that has both the meter and the branch circuit breakers, there's no way to install the Backup Gateway. So either the meter gets moved out of the meter main, or all the branch circuit breakers get moved out. Since work on the meter side requires involving the power company, it is typically less expensive to just move all the branch circuit breakers out of the meter main.

    Cheers, Wayne
     
  12. cwied

    cwied Member

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    All the conduits out of the tops go into a gutter box just out of frame to allow the wires to be run between the boxes.

    I think the reason for the generation panel is to avoid having a panel that has both loads and feeders as this makes it harder to manage the bus capacity.

    This is how the panels are connected - note that the location of the connections doesn't match the actual physical location:
    upload_2018-6-20_8-44-46.png
     
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  13. Dan123

    Dan123 Member

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    For those with two PWs, do they connect
    Thank you!

    I presume the PV inverter is located outside? There is also a data connection and a router below the main panel. I presume one (or two) data connection goes to the PW, and one goes to the gateway?

    Are you sure that the "generator" panel is not connected to the "load" panel directly. In the manual, there is a direct connection between PW and Solar to the "load" panel, and the gateway is only between the meter and the "load" panel.
     
  14. cwied

    cwied Member

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    Yes, the PV inverter is outside. The conduit that heads down from the generation panel goes through the wall.

    The network switch is mine and provides the internet connections for the Tesla Gateway and the PV inverter. The powerwalls communicate with the gateway some other way. I don't know if that's over a wire or wireless.

    I am pretty sure about the connections. I traced the wires in the gutter box and they go into the conduit heading to the gateway, not to the load panel. Besides, the load panel has no breaker for a feed from the generation panel.
     
  15. wwhitney

    wwhitney Member

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    The actual connection is at the load side lugs of the Backup Gateway, which are double lugs. So there is effectively a feeder "bus" connecting the generation panel, the backup gateway, and the loads panel.

    Cheers, Wayne
     
  16. Dan123

    Dan123 Member

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    Does the generation panel have breakers? Or the gateway switch have breakers? Something has to have breakers so that the draw from PWs does not exceed 60 amps, and the draw from the inverter does not exceed its capacity.
     
  17. wwhitney

    wwhitney Member

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    The generation panel has breakers. The gateway does not have any load side breakers.

    Cheers, Wayne
     
  18. cwied

    cwied Member

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    Wayne knows what he's talking about more than I do, so listen to what he says. Here's the picture of the generation panel confirming his statement.

    [​IMG]
     
  19. NuShrike

    NuShrike Member

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    If your solar-installer is going to change out your main meter box, see if you can get them to rewire the mains to a conduit that goes to a separate subpanel. Then from that separate subpanel, another conduit back to your meter.

    You'll need this external loop to properly prepare for the Tesla Backup gateway, and to avoid moving all of your load-breakers from your then pointless, expensive, shiny new main-meter box to a sub-panel later.

    The other way to prepare is to just move all your load-breakers into a new sub-panel and avoid upgrading your main-meter panel.
     
  20. wwhitney

    wwhitney Member

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    If an upgrade to a meter main is required for solar, then the best option to prepare for future Powerwalls would be to ensure that the branch circuit breakers are not in the same enclosure as the service disconnect. E.g. the new equipment could be a small meter main with a main breaker and subfeed lugs, along with a feeder to another main breaker panel that houses all the branch circuit breakers. Then when Powerwalls are installed, that feeder could be intercepted and rerouted through the Backup Gateway.

    Cheers, Wayne
     

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