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Installing Powerwall 2 on the same circuit as a HPWC?

Discussion in 'Tesla Energy' started by feslatan, Dec 26, 2016.

  1. feslatan

    feslatan Member

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    I'm installing a 50amp 240v circuit powering a HPWC and I'm looking at installing a Powerwall 2 in the coming months as well. My main panel is 125 amps and doesn't have the capacity for an additional circuit required for a Powerwall.

    So my question is, since the v2 HPWCs are smart and can share a circuit with up to 7 other HPWCs, coordinating timing, is the Powerwall 2 being made with the same coordinating intelligence? I'm getting a Powerwall 2 for load-shifting, charging up from the grid at night and discharging to the house during peak hours.

    If they could work together, giving the HPWC charging priority and charging the powerwall when the car is full, this would mean I wouldn't have to spend several thousands of dollars upgrading my house panel to 200 amps.

    Info on the Powerwall 2 is pretty hard to come by, but it would be good to know if there's anything special I should be doing during the current installation to make the Powerwall 2 installation easier (or possible) down the road.
     
  2. miimura

    miimura Active Member

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    I doubt that what you propose (circuit sharing between HPWC and PowerWall) is wise or even allowable by electrical code. If you're going to install a PowerWall you will probably need panel capacity for at least a 30 amp 240 volt circuit. If that means a new 200 amp panel in your particular situation, I doubt there is a way around it. You will probably have to wait until you can get a site visit from someone who installs PowerWalls to know for sure.
     
  3. feslatan

    feslatan Member

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    #3 feslatan, Dec 26, 2016
    Last edited: Dec 26, 2016
    Thank you for the reply. If I were to install a second HPWC I could do so on the same circuit because the HPWCs coordinate so they never draw load at the same time. What I'm asking is if the Powerwall will have this same coordination feature that already exists in the HPWC. I'm not asking if I can just jury-rig two high-load devices on to a single circuit.
     
  4. ecarfan

    ecarfan Well-Known Member

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    I'm not an electrician, but I own a Powerwall (the first model, not the new model). You are going to have to ask Tesla Energy for a definitive answer to your question, but it seems to me that your Powerwall is just another load on your panel, like your HPWC. It will try to charge up at night but I can't control exactly when my Powerwall charges. You can of course schedule your car to charge at any time but I assume you will charge it at night also.

    I have not seen any TMC member post that they have a Powerwall 2. You need to talk to Tesla Energy. You are going to have to talk to them anyway to get a Powerwall. You don't want to make decisions about your home electrical system based on what a stranger on the internet tells you. That includes me. ;)
     
  5. Ampster

    Ampster Member

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    I agree with most of what the previous posters have said. I would just clarify that capacity of your panel can be defined in several ways, ie the number of breakers, the total capacity of the those breakers and the total capacity of the panel. You have not specified anything other than your panel capacity. I believe there is a a calculation that allows you to have a total capacity of the sum of the breakers to exceed the panel capacity. The assumption is all of those loads will not be fully used at the same time. You would need to consult with someone more familiar with the electrical code to get the answer. My panel was filled with breakers before I added solar and my 30 Amp EVSE circuit. My electrician did a calculation and replaced a number of full space breakers with half space breakers and freed up some space in my panel.
    If you are breaker space constrained that may be a solution. I do however think there is little likelihood that the Powerwall would be programmed to share a circuit with a HPWC. There are current sensing/sharing devices that can do that but when I looked they were several hundred dollars plus installation.
     
  6. feslatan

    feslatan Member

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    I should clarify. My master electrical panel has a 125 Amp capacity and that's the limit I'm referring to. This is a limit that would require completely replacing my house's connection to the power lines, including a new power meter and a new main breaker panel (not the one filled with breakers, but the one outside that shuts off power to the house). When we got the permit to install the 50 amp circuit for the HPWC we did a full house load calculation that, among other things, added the total possible electrical load in our house, and basically discounted anything past the first 8000 watts down to 40%. The resulting number gave us enough capacity to install a 50 amp 240v circuit for the HPWC while still leaving the total calculation below the required 80%-of-master-circuit maximum.

    Part of me thinks that this is a distant hope, except that Tesla reworked the HPWC to be able to handshake with other HPWCs for *exactly* this reason, so it doesn't seem so farfetched that they might do the same with the Powerwall 2.

    I'll reach out to Tesla Energy tomorrow and will report back with my findings.
     
    • Like x 1
  7. Ampster

    Ampster Member

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    I may be in the same boat now that I have two electric cars to charge, an all electric home and also a 125 Amp panel. Let us know what you find out about the Powerwall. I may look into the current limiting switches that I saw some time ago.
     

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