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Any experience getting Tesla to "confirm" adding circuits to whole-home backup?

Has anyone added circuits to their Tesla Solar whole-home setup - how did it work? How long did it take?

I'm doing a whole-house backup (with the Backup Switch/meter collar, no Gateway). The system is bigger than we need now (8.5 kW, Powerwall+, Powerwall 2.1) specifically to be ready for electrification of more of the house over the next couple years (e.g., electric water heater, clothes dryer, induction cooktop). And, near-term I want to rework some of the house circuits (e.g., split the kitchen circuits to provide dedicated lines for the major appliances, add AFCI/GFCI breakers etc. So I need to understand if there is something I can/should do now to enable later growth/improvements.

The house was built in 1968. The existing Main Panel is an old 100A Murray which is already stuffed with tandem breakers ... no slots, no circuits space left, AFAICT. That panel is located right next to the gas riser so PG&E won't let me enlarge it or upgrade to 200A in any sane timeframe (they're talking 6 months to a year, and many thousands of dollars, because my service feed is direct-buried cable).

Tesla will use a Backup Switch (meter collar thing), and apparently just splice and extend every circuit from my outside Main Panel... the extensions will be about 50ft, where they land in a new "Building Load Center" panel in the garage, which is where the two Powerwalls hook up. The Main Panel will just have an 80A breaker cabled (AWG #4 THWN-2) to the busbar of the new BLC panel (no input breaker on the BLC's utility feed).

The Main panel gets labeled telling us to not have breakers adding up to more than the busbar's ampacity (100A, think) so after the 80A breaker there's maybe physical/electrical room for one 20A breaker in that box.

The Powerwall+ will have a 50A/2P breaker in the BLC, and the Powerwall2.1 will have a 30A/2P breaker in the BLC. The circuits to be relocated comprise 13 of 120V 20A (mostly intermittent loads - there's the refrigerator, and a 20 year old spa/hot tub which circulate/heats continuously), 6 of 15A, one 30A/2P (unused dryer), one 40A/2P (electric oven), so the new Building Load Center panel will have like 28 spaces taken up. (None of the existing breakers have AFCI or GFCI functions, so fixing that is a big part of my goals here.)

I'm assuming Tesla will install a panel with some extra spaces. (Their first plan says a 20-space/40-circuit 225A panel, and I'm trying to get my Tesla Adviser to understand that's physically too small.)

I figured new circuits could be added to the new BLC panel, after the install. (I want to restructure the kitchen circuits, for example - not new stuff, just dedicate some circuits to specific appliances.) If they're heavy loads (like, if we ever added an electric dryer or a minisplit heat pump) we'd just know to not use that during a power outage. My main concern was whether the 80A breaker between the Main Panel and the BLC was going to be enough power for the house (I haven't seen any load calculations, but our usage runs around 22 to 24 kWh/day throughout the year, and our *peak* daily load was about 30 kWh, so I'm feeling like we're probably OK.)

But, I just learned (from "construction drawings" that) that the new the panel will have a sticker "CAUTION ADD NO NEW LOADS" - so where do new loads (e.g., water heater) or new circuits (e.g., dedicated refrigerator) go? I've read in a couple threads you have to go back to Tesla to get a confirmation the new load won't "void your warranty." Has anyone actually done that? How long does it take, does it cost anything?

Bottom line, is a Tesla PV+ESS going to freeze my home configuration and make it impractical to update some safety issues or expand electrical use?
 

GenSao

Member
Aug 3, 2017
585
1,015
Pleasant Hill, CA
Wstidolph,

Welcome to the Tesla Motors Club. Enjoy your stay.

First, do a load calculation for your home to confirm what you need and may add in the future (such as EV charging). Tesla may have done this for you already. The do not add new loads is Tesla CYA. In the long term, adding new circuits will depend how comfortable an electrician/company is in modifying an existing PV+ESS system. Some will not want to to do the legwork to check the load calculations and say no.

There should be extra room (and capacity) for additional circuit breakers. Proactively ask Tesla to use tandem circuit breakers. If more room is needed, a sub-panel can be added. See below image of my (past in progress) installation with tandem circuits. As in the photo, Tesla likely will install the PV+ESS circuit breakers at the bottom and the loads on top.

IMHO 80A to the back up panel seems too small. For future growth, I would ask Tesla to match the 100A breaker for your backup panel and main power. As you are aware, doing this will not allow you to add any non backed up loads. The 225A busbar (even in consideration of the 120% rule) in the backup panel can handle the 100 A breaker.

100A grid + 50A PW2+ + 30 A PW2 = 180 A < 225 A busbar


20171115_125754_HDR.jpg
 
Thanks! Good advice on trying for a larger feed to the subpanel.

One point on using tandem breakers though, is that the run from the Main Panel to the new subpanel is over 6 feet (it's actually 40 or 50 feet of cable, I think). I *think* that means the new breakers in the subpanel are "new work" which requires arc-fault protection breakers: are there arc-fault (and/or GDCI) 20A tandem breakers?
 
Thanks! Good advice on trying for a larger feed to the subpanel.

One point on using tandem breakers though, is that the run from the Main Panel to the new subpanel is over 6 feet (it's actually 40 or 50 feet of cable, I think). I *think* that means the new breakers in the subpanel are "new work" which requires arc-fault protection breakers: are there arc-fault (and/or GDCI) 20A tandem breakers?
Replying to myself - I think I found tandem PlugOnNeutral arc-fault breakers for the HOM2040L225PRB which Tesla is proposing. (
) So maybe a 20/40 panel is OK ... using these looks like it would leave me with a some spaces/circuits open.
 

BGbreeder

Member
Jun 19, 2020
564
358
Bay Area
As painful as it is, I would get things squared away with PG&E first. You will have more options and it will cost you much less in the long run. Whether it is easier and less expensive to move the gas or the underground feed is above my pay grade. Option #2 would be to dump the gas now, and make PG&E remove the riser.

You won't be able to run that water heater dryer and induction stove with everything else on a 100A feed easily.

Personally, I would pay to have the main house panel upgraded to a 200A, 225A busbar panel, before embarking on Powerwalls. Then if you can, I would try to get Tesla to precalculate the water heater (heat pump water heater, right?), dryer, and induction stove into whatever panel you plan to wire them into (backup vs not), along with an EV charger outlet. I think that it would save you trouble and expenses later. You are bringing the house into modern usage. Why would you want to save a fifty year old piece of electrical hardware? It takes a day or so to rip out the old one and to drop in and rewire the upgrade panel. (Once the gas riser issue is sorted out.) You then could put in a 200A breaker to feed the new center in the garage.

The sticker may be CYA, but it will and does put off a number of electricians who want to wire, not do load calculations, and it will reduce your options on who is willing to do future work and the price they will charge for it.

Just my $0.02

As a total aside, why run everything 50' over to the garage? Is there some HOA regulation that prevents you from landing the Powerwalls next to the existing panel?

All the best,

BG
 
BG, thanks - good points, but ... I'd love to get squared away on 200A first, but the timeline doesn't fit my needs.

I started out wanting to relocate and upgrade the main panel and service, but my service drop is 100A direct-buried cable, so that option is way too time-consuming and expensive (PG&E guesstimated 6 months to a year and "many thousands of dollars" to do their part involving trenching and such ... the Tesla site tech that visited told me one of my neighbor's bid for that was well over $20K). Moving the gas line would let me keep the panel location, but I still wouldn't get 200A service without all that PG&E work.

That gets me to why do that at all: is 200A critical? Not really ... because my critical goal in getting PV+ESS is not the switch away from natgas, nor financial savings: it's mostly to have a safety/reliability improvement in place by next Spring, accepting a roughly 10 yr breakeven on cost. (At which point I kind of expect to sell the house, because we'll be in our late 70s and waiting to downsize). I'd *love* to get 200A, but it isn't central to the goal.

The safety goal is met by getting more reliable power in the face of outages, and in bringing some of this ancient circuitry up to a more modern implementation (get a little more space in the lead panel and I can break out dedicated circuits for appliances, etc). I'm thinking with 100A+PV+ESS I can get at least those benefits, and possibly partial elimination of gas. (I'll update one appliance at a time and see what the real world load is before moving on to the next.)

A strategy of dumping all the gas now means first doing the PG&E work, then getting my kitchen, laundry, hot water, and (brand new) furnace replaced, then going after solar ... so I'm about $30K and 18 months (including 2 winter/fire seasons) invested before I get back to Tesla (or whoever) to work on my critical reliability goal (and maybe with rising solar prices and diminishing incentives). But there's a timeline on all this, because I expect my mother to move in with us within a year, so I need the core safety improvements soon, not in 2 years. This somewhat-inelegant whole-house/100A-accepting approach isn't about trying to save old hardware, it's about trying to save time in the near term.

BTW, I wanted a partial-house backup, to support upgrading heavy appliances NOT on the Powerwalls - but Tesla told me that would take "months" longer in their design phase. Weird. Other solar vendors didn't cite that difference, but none of them could even start until early next year, and they cost significantly more than Tesla.

If PG&E could move faster, and at a reasonable price, yeah, I would just upgrade my service and main panel immediately then tackle solar. But, given the realities, I'm left wondering what I can do to ease a strategy of incremental improvement. One of my thoughts now is to get the new load center in the garage *then* start PG&E on running a new 200A service directly to that panel to become the new service entry, and then do the higher-power upgrades, and maybe even move over to partial-backup using a Span or similar panel in a couple years.

Why the long run to the garage? No HOA, but there is PG&E ... The old panel is at the corner of the house and the gas riser is just next to it, maybe a foot away. They can't put the Powerwalls on the other side of the gas riser because you can't run conduit across the gas riser zone (to the panel); and they won't put the Powerwalls around the corner because the front of the house is brickwork which Tesla won't mount to. That left them the garage, at the other end of the house.

BG, you've made me crystallize some of why I'm doing this, and that'll get me to reconfirm it and be clearer with Tesla about design - thanks!
 
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BGbreeder

Member
Jun 19, 2020
564
358
Bay Area
Glad to be is service! I get the self sufficiency and fire threat concerns; that's why we added Powerwalls to our solar.

Given what you have explained, I would be tempted to oversize the panel in the garage to be a "solar ready" 200A (25A bus bar) panel. It would be...annoying...if there was a code update between now and your main service upgrade that required a bigger panels than you had installed, but I am not an electrician or code expert. That would be @Vines or @wwhitney, amongst others. I think that the idea to move the service entry is interesting, but the devil is in the details. PG&E might give you feedback on the possibility if you ask. Perhaps others with more experience can comment on the $20k to trench in new service; again the devil is in the details. (Distance, obstacles, etc.)

FWIW: My Powerwall designer landed all of the solar and Powerwalls breakers in the Gateway bus, which is really convenient if you are considering a transfer switch and generator in the future.

All the best, and good luck on the journey,

BG
 
I think you are mixing two separate things: space on the Tesla added panel and peak load. Both are relatively easy to figure/solve in my opinion. For peak load, just calculate what it would be for all the appliances you'd run at the same time. Note that startup and steady state load are different, and consider if you'd be running and/or starting them all at the same time. If < 100A, you good without doing a thing. If > 100A, then you need to really think about where you are going to get the power (more solar, larger service, etc) For the Tesla added panel, I don't think it matters how much space is left on the panel, so long as you have a few (I think you'd need at least space for 2 double pole breakers that support up to 80A worst case). You can add a few big circuits like 30A hot water heater, oven, dryer, and then add a 50-80A subpanel, and do whatever configuration you want there for smaller circuits on the subpanel.
 
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Yeah, I'm probably mixing several things I shouldn't - this is a new set of terminology and concerns and rules (codes) for me! So, thanks for your patience/education ...

Agreed, the 100A is a peak draw limit for me, and one I'm nowhere near today. I'm worried mainly that if I go for my full expansion (hot water, etc etc including EV) in a couple years I may be well over 100A, and yes that load will mostly go onto the grid - my rooftop power gen isn't going to be anywhere near those numbers!

In the "Tesla panel" (Building Load Center) I expected I could mainly add loads based on physical/circuit space (and yes, I might exhaust the batteries, but that is an operational concern, not a permitting/legal issues, right?) so I was trying to get a bigger panel during this install, to avoid having to later put in a subpanel right next to the BLC - this was just economics. Then I saw that "ADD NO NEW LOADS" sticker and I started trying to understand why that would be, and whether it constrained my expansion, and whether Tesla would work with me when the time came. I haven't come to a crisp understanding of why that sticker is there or who it really constrains or what effect it really has. (And so far, *nobody* has said they expanded on the Tesla panel, so I'm not confident it would be a simple problem logistically/paperwork.)

If I wanted a subpanel tied as a load onto that Tesla panel, wouldn't I have to get Tesla's permission (since it represents a load or a possible load)? Then every time I add a circuit/load to the subpanel, do I again need Tesla's permission?

I grasp only part of the various rules about the busbars and OCPD arrangements, but my real concern is the permits, legalisms, processes, and the company I'd have to work through ... which, I have to say, is so far stunningly uncommunicative.
 
I am not an electrician, but am installing pretty much the same system as you with Tesla right now. In the docs, it says why each warning label is present. For that label, it says "Per NEC Code 220". I believe this is a max load calculation. Adding circuits or a subpanel should be OK as long as you do the peak current demand calculation. The worst I think that can happen is that you trip the main service 100A breaker or the PV (50A) / ESS (30A) breakers. Those breakers will isolate the main panel, PV, and ESS feeds. BTW, I think BLC means backup load center, not building load center. Yeah, if you are servicing a 5000A commercial building, you'd better fully analyze the usage and measure the demand over 30 days or a year or whatever NEC 220 says, but for a house, where you are going to add 1 new appliance, you can monitor your usage and be ok. In any case, whatever you add, presumably you are going to hire an electrician and get your AHJ to sign off on it. It has nothing to do with Tesla. The AHJ will likely want to see a load calculation also for the new circuit or subpanel
 

arnolddeleon

Member
Supporting Member
Jul 21, 2012
947
1,017
SF Bay Area
IMHO 80A to the back up panel seems too small. For future growth, I would ask Tesla to match the 100A breaker for your backup panel and main power. As you are aware, doing this will not allow you to add any non backed up loads. The 225A busbar (even in consideration of the 120% rule) in the backup panel can handle the 100 A breaker.

I suspect 80A is the largest breaker the current panel will support. If not then yes get the larger breaker.

For context 60A at 240V for 10 hours is 144 kWh. This is my way of saying I think it is unlikely that you will have problems the average. With the Powerwall+ and Powerwall 2.1 you will have surge capacity.

Induction cooktop will likely be an equal if not smaller load than your current electric cooktop. If you add an electric water heater you will likely add a heat pump one . In any case you can probably just tell Tesla to add the water heater load/breaker. It looks like you have everything else already.
 
@arnolddeleon, I hadn't thought about a "largest breaker" limit - thanks for pointing out that possibility. My current cooktop is gas, but I have an electric wall oven that has a 40A service, and I can get an induction range (oven+cooktop) to fit that, so it would be OK. My growth/change concerns really comes down to two things: I want to split some existing loads off of shared circuits to get their own circuits (as I understand is current code), and I want to be able to add an EV charger, a heat pump mini-split, maybe a heat pump water heater, maybe a heat pump dryer (in place of existing gas dryer). I might run into limits on all that which could stall me and push me to the 200A upgrade, but maybe not. However, these all seem to require adding "loads" to that Tesla panel, and I am coming to expect Tesla to be a rotten company to work with on this kind of thing, so I'm hoping to figure out a strategy to implement *now* which will ease that recurring "get permission from Tesla" later.
 
I am not an electrician, but am installing pretty much the same system as you with Tesla right now. In the docs, it says why each warning label is present. For that label, it says "Per NEC Code 220". I believe this is a max load calculation. Adding circuits or a subpanel should be OK as long as you do the peak current demand calculation. The worst I think that can happen is that you trip the main service 100A breaker or the PV (50A) / ESS (30A) breakers. Those breakers will isolate the main panel, PV, and ESS feeds. BTW, I think BLC means backup load center, not building load center. Yeah, if you are servicing a 5000A commercial building, you'd better fully analyze the usage and measure the demand over 30 days or a year or whatever NEC 220 says, but for a house, where you are going to add 1 new appliance, you can monitor your usage and be ok. In any case, whatever you add, presumably you are going to hire an electrician and get your AHJ to sign off on it. It has nothing to do with Tesla. The AHJ will likely want to see a load calculation also for the new circuit or subpanel
I worry about touching that panel affecting Tesla's warranty; I worry about that sticker making an electrician/AHJ unwilling to touch that panel; so I expect it means contacting Tesla every time I want to affect that panel, and that's why I'm trying to find out what that sticker actually means/controls, and if anyone has actually added circuits to that panel, what it turned out like in the real world.

I've asked my Adviser repeatedly about post-install expansion: no response.
 

BGbreeder

Member
Jun 19, 2020
564
358
Bay Area
Given the complexities of what you are wanting to do, I would suggest hiring your own electrician and installing the new 225amp solar ready panel in your garage, adding all of your desired breakers, and circuits, and then sitting down with Tesla. (Or just hiring a third party who wants to work with you on this.) It sounds as if what you are wanting to do is well outside of Tesla's "cookie cutter" approach. A downside would be that this probably would not have tax eligibility as a solar install. I would encourage you to speak with your tax advisor about whether if the new panel is required for the solar install, then whether some amount may be eligible for preferential tax treatment.

All the best,

BG
 
Given the complexities of what you are wanting to do, I would suggest hiring your own electrician and installing the new 225amp solar ready panel in your garage, adding all of your desired breakers, and circuits, and then sitting down with Tesla. (Or just hiring a third party who wants to work with you on this.) It sounds as if what you are wanting to do is well outside of Tesla's "cookie cutter" approach. A downside would be that this probably would not have tax eligibility as a solar install. I would encourage you to speak with your tax advisor about whether if the new panel is required for the solar install, then whether some amount may be eligible for preferential tax treatment.

All the best,

BG
You're right, that's good advice ... but, given the availability of electricians around here just now (everyone seems to be booked!) and the speed of our Planning Dept, I suspect that sensible approach would again take me well outside the timeline I want to be on (as well as boost my costs). If I get that deep into it, knowing me I'm sure I'd also go looking for the "best" solar system rather than what I expected from Tesla ("good enough, cheap enough, fast enough") and slow down the whole process yet further.

So right now I mainly want to make sure the design allows me to *later* enhance this system - maybe towards the goals I have now, or maybe towards different goals/constraints that emerge as I start living with PV+ESS. Questions like will I be able to add circuits or loads or upgrade my main to 200A etc. I just can't seem to find anyone with any experience in altering a Tesla system post-install, and that makes me nervous ...
 
My recommendation is to get installed the rough in and outlets for the electrical expansion, that way Tesla can include the breakers in the BLC.

You can put in a 30 amp 240V outlet (14-30R) for example, for a heatpump water heater.

You can put in a 50 amp 240V outlet (14-50R) for example, for an electric/induction range.

You can put in a 50 amp 240V outlet (14-50R) for an EV.

Get an electrician to run them to where the BLC will be, have the permits for the work, etc, maybe even install the BLC ahead of time as was suggested above.

That, or run try and get Tesla to include these as an additional billable cost in the install and permitting.

Adding circuits/breakers after the BLC is blessed seems to be a REALLY difficult task as no one seems to want to accept responsibility for "yes it will work" and "yes, it is safe" and "yes, it won't start tripping the power wall breakers.

-Harry
 

BGbreeder

Member
Jun 19, 2020
564
358
Bay Area
Personally, I think that a later expansion is going to require a commercial electrical contractor that has a planning group that can rerun the NEC load calculations correctly for a residential install. That is asking a great deal. "Hens teeth" leaps to mind, but I would be happy to be wrong.

All the best,

BG
 
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Maybe I'm in the minority here, but what's so hard about adding a 50A circuit to the BLC for an EV that will most likely be only running at night and you can put a smart charger that can throttle the current draw if needed.
The required label that states that additional loads can not be added to the panel....

The technical of this is easy, the paperwork and getting someone to be willing to do it, is the hard part.
 
Just ask for Tesla's load calculation submitted with the original permit for the install of the BLC. That's what I plan to do. Then when you want to add a circuit, confirm the added circuits still meets the load limits of NEC 220 based on original load calculation + added circuit. You can submit the permit yourself and show the electrician the issued permit.
 
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