Will I need a panel upgrade?

[paladaxar]

I'm a beginner when it comes to solar and residential electric (and newly a homeowner for the first time) and trying to figure out some things about my specific setup...it seems to be a little different from what others have and Tesla is of course, not very helpful in answering my questions. Some of the people I have asked have said "oh yeah, you'll need a panel upgrade for sure" and others have said "oh no, you should be fine".

So, I thought I'd ask here where the level of competency seems to be a lot higher than usual

I have a "panel" outside attached to my meter that has just 1 100A main breaker in it...attached right to the incoming lines from the street. Then that goes through the meter and then into the garage where there's a panel that has all the circuits for the house.

Our power is underground and I've heard that some people have had to pay like $15,000 to upgrade because they have to trench for a new conduit, etc.

I want to get a 12.4kW system and 2 powerwall+'s.

Can anyone explain what factors would determine whether I need a panel upgrade or not? And whether it seems like I would need an upgrade or not? Is there any other information that would be helpful?

Here are some pictures of my panels... (note: I didn't add the funny labels haha)

 

[Vines]

There are many things that might require a panel upgrade, but yours is perfect for a whole home backup system. You have a panel with just a main breaker and no distribution bus. When there is a distribution bus in your service panel things get more complicated.

I think if you brought this to Tesla they would recommend one PW+ and one PW, which is a decent solution in your case.

It also looks like your essential loads subpanel has a spot for a 100A main breaker in the deadfront, likely the panel itself has a location to install this main breaker but to be 100% sure you need to remove the deadfront.

 

[CrazyRabbit]

What CLXXX number is on your meter? 100 or 200, that is your service size.

 

[paladaxar]

Wow, @Vines …you are so helpful…once again! I wish I could have you as our installer

There are many things that might require a panel upgrade, but yours is perfect for a whole home backup system. You have a panel with just a main breaker and no distribution bus. When there is a distribution bus in your service panel things get more complicated.

That’s so good to hear! Out of curiosity, and wanting to see the big picture, I’m trying to understand this a little better…if I wasn’t doing a whole house backup, would I need a panel upgrade?

I think if you brought this to Tesla they would recommend one PW+ and one PW, which is a decent solution in your case.

Would they ever do two PW+‘s? Or is that not even possible? I’m thinking it would be good to have two inverters for 12.4kW. I have a long way to go to understand all of this :/

It also looks like your essential loads subpanel has a spot for a 100A main breaker in the deadfront, likely the panel itself has a location to install this main breaker but to be 100% sure you need to remove the deadfront.

So by installing powerwalls, they need to add a 100A breaker to my loads subpanel? And then all of the other breakers would be connected to that new 100A breaker?

As a side question, could they ever install more than 100A? Like could I get a 200A breaker in my loads subpanel instead of the 100A? Right now my house has a 240v outlet for EV charging…but it’s on a 20A breaker. It would be nice to move that up to 40A, but I’m guessing they went with 20A when they put it in because the load calculation sheet that they filled out with the permit came to 98A (so nice of the previous owners to leave that stuff). So I’m guessing they went a little smaller than usual to avoid going over 100A for the whole house. In the future, it would be nice to have faster EV charging (and maybe a second EV charger) and an electric water heater and a heat pump etc…going all electric since we’ll have so much solar.

 

[paladaxar]

What CLXXX number is on your meter? 100 or 200, that is your service size.

Hmm…I’m a little confused, because my meter says CL200…but the main breaker is only 100A. What do you make of that?

 

[CrazyRabbit]

You have 200 amp service. You could change the breaker to a 200 amp breaker, up size the wire to the panel if the panel bus is 200 amp.

 

[paladaxar]

You have 200 amp service. You could change the breaker to a 200 amp breaker, up size the wire to the panel if the panel bus is 200 amp.

I wonder if there’s a chance that I have a 100A service (meaning that’s the most that can come on through the wires coming to the house), but they put a meter on at some point that’s capable of “up to” 200A. Or is that not how it works? The meter is definitely newer than the house…so I’m sure it was upgraded at some point.

 

[Vines]

Wow, @Vines …you are so helpful…once again! I wish I could have you as our installer

You could if you wish to PM me. I am happy to help regardless.

That’s so good to hear! Out of curiosity, and wanting to see the big picture, I’m trying to understand this a little better…if I wasn’t doing a whole house backup, would I need a panel upgrade?

Not necessarily, but you would need an additional subpanel connected to the Tesla Gateway on either the line side or the non-backup lugs.

Would they ever do two PW+‘s? Or is that not even possible? I’m thinking it would be good to have two inverters for 12.4kW. I have a long way to go to understand all of this :/

Multiple Powerwall+ can be installed in the same location. If you requested a 13+kW system, they would probably start thinking about a second inverter, probably a separate 3800w inverter. If you ordered a 17+kW system then they would start looking at a pair of PW+ with the built in 7600w inverter.

So by installing powerwalls, they need to add a 100A breaker to my loads subpanel? And then all of the other breakers would be connected to that new 100A breaker?

Since the subpanel would have 2 sources of power, each able to provide a total of more than 100A, a 100A main breaker in the subpanel is required to protect the wire and equipment.

As a side question, could they ever install more than 100A? Like could I get a 200A breaker in my loads subpanel instead of the 100A? Right now my house has a 240v outlet for EV charging…but it’s on a 20A breaker. It would be nice to move that up to 40A, but I’m guessing they went with 20A when they put it in because the load calculation sheet that they filled out with the permit came to 98A (so nice of the previous owners to leave that stuff). So I’m guessing they went a little smaller than usual to avoid going over 100A for the whole house. In the future, it would be nice to have faster EV charging (and maybe a second EV charger) and an electric water heater and a heat pump etc…going all electric since we’ll have so much solar.

If the wire and equipment is rated for the current, you could have more than 100A feeding your essential loads subpanel. Without a service upgrade the max that would come from the grid is 100A,

 

[Vines]

I wonder if there’s a chance that I have a 100A service (meaning that’s the most that can come on through the wires coming to the house), but they put a meter on at some point that’s capable of “up to” 200A. Or is that not how it works? The meter is definitely newer than the house…so I’m sure it was upgraded at some point.

The only way to tell is to see the PGE hot conductors under the (missing) PGE tag on the hot side. The meter size is not the answer.

If the PGE wire is good for 200A then you have a 200A service. From experience in this area, I have only one time seen wire larger than needed pulled to a service.

I have seen CL200 meters on 400A services, I have seen CL 480 Meters on 400A services so the meter is only related to the service size in PGE territory.

 

[wwhitney]

If the PGE wire is good for 200A then you have a 200A service. From experience in this area, I have only one time seen wire larger than needed pulled to a service.

Do you know the sizing methodology PG&E uses on their underground services, say for 100A, 125A, and 200A? I understand that wire is under the control of PG&E and so not sized per the NEC.

Cheers, Wayne

 

[Eric99]

Your meter main looks exactly like mine(same color stucco too). I think your setup would look very close to mine. Tesla is on my roof as we speak installing.

 

[paladaxar]

Your meter main looks exactly like mine(same color stucco too). I think your setup would look very close to mine. Tesla is on my roof as we speak installing. View attachment 834226View attachment 834228

Nice, yeah, it looks like we have a very similar setup. Even your gas meter and placement are just like mine. Do you have a 100A breaker in that box next to the meter?

Also, how much solar are you getting? And is that box next to the gateway the main (only?) panel for all of your house loads? And is it 100A or 200A?

 

[Vines]

Do you know the sizing methodology PG&E uses on their underground services, say for 100A, 125A, and 200A? I understand that wire is under the control of PG&E and so not sized per the NEC.

Cheers, Wayne

It is hard to know what they know with any surety.

From what I have seen, the incoming conductors are approximately 2 sizes smaller than the NEC would require for a similar branch circuit.

 

[Southpasfan]

You could if you wish to PM me. I am happy to help regardless.

Not necessarily, but you would need an additional subpanel connected to the Tesla Gateway on either the line side or the non-backup lugs.


Multiple Powerwall+ can be installed in the same location. If you requested a 13+kW system, they would probably start thinking about a second inverter, probably a separate 3800w inverter. If you ordered a 17+kW system then they would start looking at a pair of PW+ with the built in 7600w inverter.


Since the subpanel would have 2 sources of power, each able to provide a total of more than 100A, a 100A main breaker in the subpanel is required to protect the wire and equipment.



If the wire and equipment is rated for the current, you could have more than 100A feeding your essential loads subpanel. Without a service upgrade the max that would come from the grid is 100A,

Believe me, Vines has the actual answers, but since you are, as I was, a total layman, note the following:

1. There are a lot of technical terms, you will learn many of them.
2. I believe its accurate to say, since you are in California, that the picture of the "panel" showing the lines coming in from the street will be referred to as "the main Panel."
3. And your picture of the load center in your house, which we laymen tend to think of as "the panel" is actually a "load center" or a "sub-panel."
4. Its common, and I don't know why, for, say 200 amps to come from the street but the connection between the main panel and load center to be only 100 amps.
5. This will matter. Both as to the size of the panel and also to the size and composition of the wire between the main panel and load center.
6. Once a system with solar and ESS is installed, the safe assumption is that the electricity from the street, the solar from the Panels, and any additional electricity from the Powerwalls all could go through the system to the load center at once.
7. At least that was my take.
8. So, at the moment, due to (a) the 100 amp breaker in your main panel and (b) the size of the wire to the load center, and (c) the size of the load center itself, it looks like the load center/"house" is limited to 100 amps.

9. In my case the upgrade was (1) absolutely needed new wire from main panel to load center, (2) absolutely needed new load center, and (3) once you needed (1) and (2) there is no point in trying to figure out of the old main panel can still work with different breakers or bus bar or whatever.

My guess is you need to upgrade. Its not like there is any reason not to do so, it really benefits the entire house in addition to the solar and ESS system.

 

[Eric99]

9.14 roof. Yes its 100amp in the meter main. They side tapped that and connected it to a 200amp box next to the gateway. That has a 100amp breaker feeding my subpanel inside. Whole house backup

 

[Vines]

9.14 roof. Yes its 100amp in the meter main. They side tapped that and connected it to a 200amp box next to the gateway. That has a 100amp breaker feeding my subpanel inside. Whole house backup

What do you mean by "Side Tapped"?

 

[Vines]

8. So, at the moment, due to (a) the 100 amp breaker in your main panel and (b) the size of the wire to the load center, and (c) the size of the load center itself, it looks like the load center/"house" is limited to 100 amps.

Correct, but if the panel and wire was replaced, you could serve loads larger than 100A while there was PV or PW resources. This isn't really like adding additional service capacity, but it is similar in that you can serve more than 100A of loads. Likely a load like a car charger (especially used at night) would not cause any issues, but the load calculations need to work out for new loads like a larger car charger circuit.

 

[Southpasfan]

Correct, but if the panel and wire was replaced, you could serve loads larger than 100A while there was PV or PW resources. This isn't really like adding additional service capacity, but it is similar in that you can serve more than 100A of loads. Likely a load like a car charger (especially used at night) would not cause any issues, but the load calculations need to work out for new loads like a larger car charger circuit.

Yep, and in my case the panel (load center) and wire were replaced. I mean, there was no real reason to argue against it, in my case the older wire and load center was 100 amps and it was upgraded to 150 amps. The wire connecting the main panel to the load center was not only a bit too small, but was aluminum rather than copper, and I was told that was a bit cheap and that aluminum could get hotter.

Anyway, after those things were both upgraded they upgraded the main panel as well, because it needed a new meter. So that is probably what may happen to original poster.

Basically, for us non-electricians, installing solar panels and powerwalls results in an increase in the total electricity which can be sent to the house, because equipment is rated by the amount of total electricity, there is not reason not to upgrade or try to argue ones way around it.

 

[paladaxar]

Since the subpanel would have 2 sources of power, each able to provide a total of more than 100A, a 100A main breaker in the subpanel is required to protect the wire and equipment.

If the wire and equipment is rated for the current, you could have more than 100A feeding your essential loads subpanel. Without a service upgrade the max that would come from the grid is 100A,

Since we seem to have 100A service and since it seems that the current load center is pretty much maxed out, it would be nice to have the ability to expand more in the future (adding/upgrading circuits for faster EV charging, heat pump, more circuits, etc) since we will have three power sources (grid, pv and pw) instead of just 1 (grid). So would our load center need to be upgraded to be able to handle a 200A breaker that feeds into the other breakers in the load center? Is this something that Tesla does often? And is there a typical charge for that?

IF that's allowed, then my next question is this: if I upgrade my load center to be able to do 200A to the house, but still have just 100A grid service, if I have multiple power sources (grid, pv and pw), and I can draw lots of power during the day when all three are available, and I have breakers tied off of the 200A that allow that kind of current to be drawn, what happens when some of those power sources are gone? Let's say at night with dead powerwalls...if I have enough running in the house to pull 150A, will the grid breaker just trip? It seems logical that that's what would happen, but would it be allowed to have more load in the house than the grid service allows? Would PG&E or San Jose permitting say "that's a no"? Or does the gateway somehow limit the draw from the grid to 100A? Or is it just on me to make sure I don't draw too much power when I have only one source, and they're cool with that as long as I'm ok with my main 100A breaker (the one tied to the meter) tripping?

 

[Eric99]

What do you mean by "Side Tapped"?

I thought he was going to do a “line” tap. But now that i think about it, im guessing its
Service—>metermain—>loadcenter—> house subpanel