Powerwall with Combination Service Panel

[iPlug]

We are considering adding Powerwalls in the next few years.

We have a Square D Combination Service Panel (see below), solar PV, and are contemplating a Powerwall setup for whole home battery backup. For this arrangement, the Powerwall gateway would go between the main panel and utility meter.

Question: is this possible with our combination service panel, or would we have to breakout the main breaker load center from the meter?

 

[GenSao]

With a combination service panel, backup loads (and solar) will likely have to be relocated to a new load panel. I have a similar setup. See below layout.

Do note, Tesla likely will derate your breaker connection to the load center to comply with the 120% rule. If you want to maintain a higher connection, consider requesting a 225A (or higher) load center.

 

[Tam]

...possible...

My guess is: For flexibility, I would have a separate meter rather than an integrated one.

 

[iPlug]

With a combination service panel, backup loads (and solar) will likely have to be relocated to a new load panel. I have a similar setup. See below layout.

View attachment 468167

Do note, Tesla likely will derate your breaker connection to the load center to comply with the 120% rule. If you want to maintain a higher connection, consider requesting a 225A (or higher) load center.

Our main service panel is full and we also have 3 sub panels. Your suggestion seems best.

Thinking of adding a large load center panel just inside the garage from the main combination panel, moving most or all current loads to that, and placing the gateway in between so we can have full home backup. Would probably go with 3 Powerwalls.

 

[GenSao]

Our main service panel is full and we also have 3 sub panels. Your suggestion seems best.

Thinking of adding a large load center panel just inside the garage from the main combination panel, moving most or all current loads to that, and placing the gateway in between so we can have full home backup. Would probably go with 3 Powerwalls.

That will work.

Just as an example, say you have 40 A of Solar (max for an existing 200 A main load center) with 3 Powerwalls (30 A each). Assume a new 225 A backup load center is used (250 A panels seems to be quite expensive).

225 A x 120% = 270 A max power circuits
40 A Solar + 3 X 30 A Tesla Powerwall = 130 A
270 A - 130 A = 140 A Available for grid circuit breaker, use next lowest breaker.
140 A > 125 A circuit breaker to back up load center from existing load panel.​

To not drain your Powerwalls overnight, do consider having EV charging outside of the backup load center. With the above example, you can have a total load of 75 A be used in the existing load center as a non-backed up load (200 A - 125 A = 75 A). A 60 A Tesla wall connector can be installed. A NEMA 15-50 EV plug can be connected to the new backup load panel in the garage to allow a reasonable charge rate to an EV from the batteries.

As it is just software, I hope Tesla in the future will integrate Powerwalls and charging Tesla cars. The cars could be specifically set to charge by solar power only (after Powerwalls are charged to a set level). In the event of a power outage, charging can stopped or limited (depending on battery states, time of day, settings, etc.).

 

[DragonWatch]

First, I am not an Electrician. Bought this home five years ago and have been in the mode of updating and upgrading this poor not real old home ever since.

At the beginning of October, I had both 200 Amp main panels replaced in preparation of putting solar panels on the roof. The replaced panels were installed by the original owner’s uncle and failed my standards, plus the electrical provider twenty years ago installed the CT box inside the garage. Last Monday & Tuesday we had the roof re-shingled. Again, the original owner touted new shingles, but failed to state that the new shingles were laid over the previous set. Again against my grain.

Next Thursday we kick off the install of solar panels & two Tesla Powerwall’s. So far it sounds like everything minus the solar panels due to a delay on their delivery Being a dyed in the wool Tesla/Elon fan boy; we would have gone fool bore with a Tesla roof, but not being available in my part of Washington yet, tax incentives, no state tax and at least being able to get Powerwall’s ~ well here we are.

FYI ~ the new electrical panels are square D.

So, if you are interested ~ once it is done, I can update you on life in the solar lane.

 

[SoundDaTrumpet]

Our main service panel is full and we also have 3 sub panels. Your suggestion seems best.

Thinking of adding a large load center panel just inside the garage from the main combination panel, moving most or all current loads to that, and placing the gateway in between so we can have full home backup. Would probably go with 3 Powerwalls.

The suggestion @GenSao suggested works only if your combo service panel supports a branch circuit breaker of 150A. Most panels only accept 125A as there largest branch breaker. Provide more details to the service panel in question such as the model number and photo of the label.

 

[iPlug]

The suggestion @GenSao suggested works only if your combo service panel supports a branch circuit breaker of 150A. Most panels only accept 125A as there largest branch breaker. Provide more details to the service panel in question such as the model number and photo of the label.

SC3040M200F (see below).

Indeed our main panel supports a maximum branch breaker of 125A. We already have 60A Solar PV on that panel so that + 3x Tesla Powerwalls = 150A.

Suggestions?

 

[wwhitney]

HOM2150 is a 4-space 150 amp double pole Homeline breaker:

HOM2150 - MINIATURE CIRCUIT BREAKER 120/240V 150A | Schneider Electric

It uses 4 spaces so that it can have two connections to each bus, to avoid drawing more than 125A from any one bus connection.

Your panel label seems to suggest it is not permitted to be used in your panel, but I'm not sure why it wouldn't be. An inquiry may be in order.

Cheers, Wayne

 

[GenSao]

@SoundDaTrumpet is correct. I was not aware of that limitation.

SC3040M200F (see below).

Indeed our main panel supports a maximum branch breaker of 125A. We already have 60A Solar PV on that panel so that + 3x Tesla Powerwalls = 150A.

Suggestions?

View attachment 468651

@iPlug , For your situation, there are a couple options:

1) Up-size 250 A backup-load panel with 125 A branch breaker (Recommended)

60 A Solar + 3 X 30 A Tesla Powerwall + 125 A power line branch breaker = 275 A
250 A x 120% = 300 A max power circuits
275 A < 300 A, OK!​

2) 225 A backup-load panel with downsize 100 A branch breaker

60 A Solar + 3 X 30 A Tesla Powerwall + 100 A power line branch breaker = 250 A
225 A x 120% = 270 A max power circuits
250 A < 270 A, OK!​

3) Only go with 2X Powerwall, 225 A backup-load panel with 125 A branch breaker

60 A Solar + 2 X 30 A Tesla Powerwall + 125 A power line branch breaker = 245 A
225 A x 120% = 270 A max power circuits
245 A < 270 A, OK!​

4) 225 A backup-load panel with 125 A branch breaker AND generation sub-panel.*

60 A Solar + 3 X 30 A Tesla Powerwall limited to a 125 A breaker in 200 A backup load panel
125 A generation breaker + 125 A power line branch breaker = 250 A
225 A x 120% = 270 A max power circuits
250 A < 270 A, OK!
* I am not sure this is possible with the NEC. Would protect the busbar of the 225A load center.​

5) If 150 A branch breaker or greater is desired, upgrade main electrical panel.

In all cases, to not drain your Powerwalls overnight and mitigate for the reduced branch breaker, do consider having EV charging outside of the backup load center.

 

[iPlug]

Appreciate the info. Would consider one of our two NEMA 14-50 charging circuits placed outside the backup load center as well as spa (50A) and pool pumps (30A).

 

[SoundDaTrumpet]

@iPlug , @GenSao 's recommendations are quite decent. Tesla has been installing an Eaton 225A bus panel for everything installation I've seen posted here. In fact, it's one compact beast, and is shorter than the Murray 125A it replaced by several inches.

In my home, I did the #3 route with using a 125A branch breaker which powers my home. The loads not backed up by the PW is the 100A Tesla charge circuit & 70A A/C subpanel. I still have room for more solar or 3rd PW if I chose in the future. Adding a generation load panel would free up more space and more capacity. Maybe @wwhitney can confirm this as the next step in the waterfall of decision points.

As for home EV charging, quite surprised the City of Fremont approved my 100A Tesla Wall Connector circuit being added to the existing 40A EVCS. I had to ask the inspector if the load calcs checked out. Yeah, throwing a wrench into my own project... being something I added last minute... I just wanted it done properly! He said the permit office confirmed this, and his intuition said 200A service, good to go! (The 40A EVCS, not regularly used, is PW backed up for outages.)

 

[iPlug]

...Tesla has been installing an Eaton 225A bus panel for everything installation I've seen posted here.

Do you know how many spaces and circuits come on their panel? Our 30 space/40 circuit panel is maxed out, including with quad breakers.

Leaning towards option #3 in the future as well. #5 sounds the nicest, but is very expensive. Not just an expensive new panel and tear out and re-stucco, but if I understand correctly, once you upgrade the main panel the city will require all new breakers up to the latest codes for new building installs.

 

[SoundDaTrumpet]

Do you know how many spaces and circuits come on their panel? Our 30 space/40 circuit panel is maxed out, including with quad breakers.

Leaning towards option #3 in the future as well. #5 sounds the nicest, but is very expensive. Not just an expensive new panel and tear out and re-stucco, but if I understand correctly, once you upgrade the main panel the city will require all new breakers up to the latest codes for new building installs.

The new panel is model BR1224L200R. 12 spaces and 24 circuits.

#5 is an automatically $3600-4000 "main panel upgrade" line item add-on.

 

[xanatos]

The new panel is model BR1224L200R. 12 spaces and 24 circuits.

#5 is an automatically $3600-4000 "main panel upgrade" line item add-on.

Sorry to dig up an old thread, but does panel upgrade really cost that much?
I am considering adding solar and/or powerwall but I only have an 100A panel, so I am worried that if a panel upgrade is needed and really costs that much, I will be over budget.

 

[Ampster]

Sorry to dig up an old thread, but does panel upgrade really cost that much?

The panel itself only costs a few hundred dollars. In my case they had to did a 20 foot trench and run new conductors. Coordinating with the utility and the county building department was also time consuming. Mine was not a Tesla install and they did not realize how much work was involved. The panel upgrade was the difference in two competitive bids at similar prices.
Short answer is it can be expensive. There are some less expensive workarounds that a competent electrician can help you with.

 

[SoundDaTrumpet]

What @Ampster did is way beyond a “main panel upgrade.” That is a service upgrade which is much more. I would say at least $2000 more just to trench. Your house likely will be disconnected from the grid for a few days and utility will attempt to keep the lights on with temporary cables. In my case I slipped thru a very narrow allowable method and avoided the $3600. If you have NO MAIN BREAKER / MAIN LUG ONLY panel, I can help.

 

[Ampster]

Yes, that is an important distinction. I went from 100Amps to 200Amps. In retrospect a newer panel would have been adequate because I self consume a lot.

 

[CalMdl3]

Do you know how many spaces and circuits come on their panel? Our 30 space/40 circuit panel is maxed out, including with quad breakers.

Leaning towards option #3 in the future as well. #5 sounds the nicest, but is very expensive. Not just an expensive new panel and tear out and re-stucco, but if I understand correctly, once you upgrade the main panel the city will require all new breakers up to the latest codes for new building installs.

I have the same integrated Square D Panel SC3042M200PF. I upgraded it three years ago when I wanted a 200 AMP panel. I am on order for a Tesla 12.24 Kwh solar system and 3 power walls. Tesla notified me that they now need $5K extra to do a main panel upgrade. I assume reading the thread it is because I have an integrated meter/ panel. I would be willing to ditch one powerwall to avoid a panel upgrade charge. I have 100 amp subpanel that has most of what I want backed up (lights, fridge). I wish Tesla would explain the various options; however, their project coordinators seem to barely know anything. What did you end up doing? Can you post a pic of your install and system?

 

[iPlug]

I have the same integrated Square D Panel SC3042M200PF. I upgraded it three years ago when I wanted a 200 AMP panel. I am on order for a Tesla 12.24 Kwh solar system and 3 power walls. Tesla notified me that they now need $5K extra to do a main panel upgrade. I assume reading the thread it is because I have an integrated meter/ panel. I would be willing to ditch one powerwall to avoid a panel upgrade charge. I have 100 amp subpanel that has most of what I want backed up (lights, fridge). I wish Tesla would explain the various options; however, their project coordinators seem to barely know anything. What did you end up doing? Can you post a pic of your install and system?
View attachment 592625

We haven’t moved ahead at this time. Unsure if we’ll stay in this house more than a few more years so holding back for now.