Southern California

Residential 3 powerwalls

Need some advise. I live in San Diego and does anybody know the do's and dont's of installing 3 powerwalls? Im getting mixed messages. Ive been told SDG&E requires a 2nd meter, and others telling me SDG&E would need to install a new main service panel to handle the meter. IT would then become a commercial grade meter. New Trenching, New wires. One saying it will cost about $2k and another $10K. Big difference. Anybody with experience with this please chime in.
I already have solar, but got the solar before I got my Model S.
I know I qualify for 3 based on the amount of energy I use on a regular basis.


  • edited March 2020
    I just went through a San Diego install of 3 PWs late last year. Same as you already had solar and just wanted 3 PWs. Even last year there was a lot of confusion about the 2nd meter, but we got it all sorted, installed, and have been operating for several months.

    A few things, the 2nd meter is JUST to monitor the solar production nothing else, it's installed in a small box somewhere near your existing meter. I think SDG&E charged around $300 for the 2nd meter, our installer paid this cost because they get a SGIP rebate for it. The cost of installing the 2nd meter box was rolled into our total contract, but I suspect it was only a few hundred $ worth of hardware and very simple to install on the solar feed. IMO the 2nd meter is a waste since your Tesla says they may be required to share your generation with the utility, but whatever we had to install it. This 2nd meter did require an extra SDG&E inspection and a separate visit for the installation of the meter. The County inspector and the meter installer commented ours was one thet had seen, so at least in our area I think these 2nd meters are new for everyone involved.

    Regarding a commercial panel to for the 2nd meter, seems like someone doesn't understand what this 2nd meter is for. We kept our same main panel and existing meter NP. However we did install a whole new 400 amp main panel next to the existing one. This had nothing to do with the 2nd meter but rather we wanted the whole house to be blacked up by the PWs rather than a couple circuits. This added couple $k to the install cost but was well worth it! This 400 amp panel was a commercial one, but in the way it's used, it didn't require any changes to the existing SDG&E service, i.e. no trenching or new wires needed.

    As for qualifying for the rebate, you will need to have a 10kw solar system to get the rebate for all 3 PWs. We were a little short and had to install more panels to meet that requirement. That part was no big deal and I did that work myself and had the changes included in the permit for the PWs.

    All in all the PWs are awesome, totally love them. I'd say we are still in the early adopters period and paying a premium, so don't expect a fast ROI. We've lost SDG&E power since the finished installation and didn't even notice. The Tesla app for the car/PW solar is way cool and informative. I would HIGHLY recommend making the investment in PWs, I'm sure you will be happy with them like we are.
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