Designing Main Panel Replacement for Future Powerwall

[Kris24D]

I'm about to undertake an extensive exterior remodel that includes demolishing a chimney (to make room for Powerwalls among other things), removing my old breaker panel , and installing a new one with more circuits (I've been electrifying a lot of my gas appliances lately). Given the backlog on Powerwall installations in my area, I won't be installing a Powerwall system as part of this project, but I'd like a future Powerwall system installation to be as seamless as possible.

From some research and reading threads on the forum, it sounds like I would need a separate meter and panel rather than a combined/all-in-one panel to support a whole home backup configuration, so I've allowed for that in my proposed layout. My thinking is to have the breaker panel and meter positioned in such a way as to allow connecting to the side and bottom knockouts of the Powerwall Gateway, resulting in a fairly clean layout post-Powerwall installation.

Does this approach seem reasonable? Any potential pitfalls I should watch out for? Thanks in advance for any advice you can provide.

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[mongo]

I'm about to undertake an extensive exterior remodel that includes demolishing a chimney (to make room for Powerwalls among other things), removing my old breaker panel , and installing a new one with more circuits (I've been electrifying a lot of my gas appliances lately). Given the backlog on Powerwall installations in my area, I won't be installing a Powerwall system as part of this project, but I'd like a future Powerwall system installation to be as seamless as possible.

From some research and reading threads on the forum, it sounds like I would need a separate meter and panel rather than a combined/all-in-one panel to support a whole home backup configuration, so I've allowed for that in my proposed layout. My thinking is to have the breaker panel and meter positioned in such a way as to allow connecting to the side and bottom knockouts of the Powerwall Gateway, resulting in a fairly clean layout post-Powerwall installation.

Does this approach seem reasonable? Any potential pitfalls I should watch out for? Thanks in advance for any advice you can provide.

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Are you planning on backing up everything? If not, a main panel with pass through lugs can hold the non-backed up loads and then feed the gateway.

Also, make sure the new panel has bus bars rated for the solar and Powerwall currents in addition to the main breaker.

 

[JeremyWhaling]

I like the siemens load centers, which can convert between main breaker and main lug using a kit. Bonus for copper bus, too. I have the 30 circuit version of this guy: Siemens PL Series 225 Amp 54-Space 70-Circuit Main Lug Indoor Load Center-P5470L1225CU - The Home Depot

 

[Kris24D]

Are you planning on backing up everything? If not, a main panel with pass through lugs can hold the non-backed up loads and then feed the gateway.

Also, make sure the new panel has bus bars rated for the solar and Powerwall currents in addition to the main breaker.

Yes, the goal is to have backup power available for my whole home, though there are some loads (e.g. EV, dryer, oven) that I would rarely run during a backup power scenario.

As long as the Powerwall gateway is installed between the meter and the main breaker panel, I wouldn't need to factor Powerwall current into the bus bar rating, correct? My understanding is that for that configuration, the main breaker for the panel should prevent the combination of grid + Powerwall current from overloading the bus bars.

I think I would still need to watch out for the 120% rule with my solar inverter currents, though.

 

[Kris24D]

I like the siemens load centers, which can convert between main breaker and main lug using a kit. Bonus for copper bus, too. I have the 30 circuit version of this guy: Siemens PL Series 225 Amp 54-Space 70-Circuit Main Lug Indoor Load Center-P5470L1225CU - The Home Depot

Thanks for the suggestion! I didn't realize there were subpanel load centers that can be converted to be a main breaker. This was the one I was originally considering: Homeline 200 Amp 40-Space 80-Circuit Outdoor Main Breaker Plug-On Neutral Load Center.

 

[mongo]

Yes, the goal is to have backup power available for my whole home, though there are some loads (e.g. EV, dryer, oven) that I would rarely run during a backup power scenario.

As long as the Powerwall gateway is installed between the meter and the main breaker panel, I wouldn't need to factor Powerwall current into the bus bar rating, correct? My understanding is that for that configuration, the main breaker for the panel should prevent the combination of grid + Powerwall current from overloading the bus bars.

I think I would still need to watch out for the 120% rule with my solar inverter currents, though.

The powewalls each get a 30amp breaker somewhere, they won't connect directly to the gateway. You could have a 200A generation panel with solar and PW that connects to the load side of a 200A service disconnect GW along with your main panel with a 200A breaker.
If you use powerwalls to reduce peak load, then they add the the busbar current (if you have a lot of loads). However, the system may limit their current in that situation (not sure on those particulars).

 

[aesculus]

As was pointed out above you probably can leave whatever you don't want backed up in the current main panel and just have the installer install pass through lugs to a new load center for the backed up breakers. Plus I think there will be another small panel that you will need for the solar generation. I have that in addition to what you diagramed.

One thing you need to consider, that looks bad in your picture, is the height of the panels. Check your building codes but there is a minimum and maximum height for panels. It's hard to tell from the picture but the GW looks like it would be too high to pass this requirement.

 

[Kris24D]

Thanks for the input, everyone. I have an updated proposed layout with the following changes:

• Added a generation subpanel for solar and Powerwalls to avoid 120% rule
• Adjusted height of the main breaker panel and backup gateway to comply with the 6'7" height limit for breakers. From poking around the installation manual, it seems like the breakers inside the backup gateway are about 6" from the top, so I could probably move both it and the main panel up by a few inches.

 

[aesculus]

The one challenge you could have is that each of your breakers in the main panel have to be moved over to the backup panel. That essentially means either that panel replaces the load center part of your existing main panel of they will have to put in pigtails for each breaker and it will require another conduit and box to go from the house wiring to the backup panel. The installer may have a preference here since they have to juggle all of this.

 

[BrettS]

In the end I think panel placement is probably going to be up to the engineers and the electricians. There are a lot of variables that affect the number and size of the panels as well as what needs to be connected to what and which wires need to run through where. Additionally, I believe that not only is there maximum height for the panels, but there is also a minimum height and I’m not sure that your panel that’s only 12” off the ground is going to meet code either. I think this is a case where you’ll probably just need to let the professionals do their job and figure out how and where to place everything that you need. They’re used to working in limited spaces and working around obstacles, so I’m sure they’ll be able to figure out a way to make everything work for you.

 

[mongo]

In the end I think panel placement is probably going to be up to the engineers and the electricians. There are a lot of variables that affect the number and size of the panels as well as what needs to be connected to what and which wires need to run through where. Additionally, I believe that not only is there maximum height for the panels, but there is also a minimum height and I’m not sure that your panel that’s only 12” off the ground is going to meet code either. I think this is a case where you’ll probably just need to let the professionals do their job and figure out how and where to place everything that you need. They’re used to working in limited spaces and working around obstacles, so I’m sure they’ll be able to figure out a way to make everything work for you.

That is also a sensible route.
Regarding min height, the only thing I've ever found on that is for mobile home external boxes. Industrial cabinets go to the floor. That said, you deffinatly want it above the high water line.

 

[diyguy]

I also prepped my electrical upgrades so the PW could go in with a minimum of additional wiring. This was without PV, grid charge only. The main things were (1) identifying where the components would go and (2) having a junction box preinstalled with a generous service loop of wire for the Tesla installers. The photo shows the sub panel with backed up loads, the junction box, gateway, and PW.