Ok, so if I understand this correctly, this is the setup you had before Tesla: service-->metermain-->"single, all-in-one load center/house panel". I think that's the setup that I currently have. Then, Tesla added another circuit breaker panel right off the output of the gateway that's now the "load center" and can do branch circuits up to 200A...one of which is a 100A branch that goes to your old house panel which is now just a "sub panel"? Did I get that right? And did they charge you extra to do that? Or is it standard practice?
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Will I need a panel upgrade?
- Thread starter paladaxar
- Start date
Exactly right. No extra charge. I “think” the extra panel wasn’t actually necessary and the could have just gone straight to the gateway. But i have been hinting to them all along that i need space to add EV charging and my house subpanel is full. I doubt i had any influence on their design though.
Ok, so I just got off the phone with PG&E and they said that my service is currently 200A...and that I "can go up to 320A" (but I think they said they would just need to put in a new panel for that).
That's great news, but, I find it hard to believe. For one they said "if your main breaker says '100 and 100', that means you have a 200A service". My main breaker does have two 100's on it, but I was under the impression that that's still just 100A.
Second, the wires coming into the main breaker don't seem to be big enough to be 200A...from what I've read online, 200A needs awg #4/0...which I think is a lot bigger than the wires I have. I measured my wires and they are about 3/8 of an inch in diameter -- WITH the insulation.
So does PG&E know something I don't? Or are they more clueless than I am?
That's great news, but, I find it hard to believe. For one they said "if your main breaker says '100 and 100', that means you have a 200A service". My main breaker does have two 100's on it, but I was under the impression that that's still just 100A.
Second, the wires coming into the main breaker don't seem to be big enough to be 200A...from what I've read online, 200A needs awg #4/0...which I think is a lot bigger than the wires I have. I measured my wires and they are about 3/8 of an inch in diameter -- WITH the insulation.
So does PG&E know something I don't? Or are they more clueless than I am?
jgleigh
Member
You're looking at the wires going to your sub-panel and those are sized for the 100A breaker. The wires to the meter are hidden and sound like they're sized for 200A or 320A.
They are confused. You can't tell the size of the service conductors by looking at your one main breaker.
They are confused. You can't tell the size of the service conductors by looking at your one main breaker.
Oh my goodness...I think you're right, @jgleigh! I feel so silly now. At some point I guess I assumed those wires were going into the meter (maybe because they're accessible from the outside of the house?) But I think you're right...I think those wires on the right side of the meter are actually coming out of the meter (not going in) and going to the breaker box in the garage. And, again, I think you're right that the wires going INTO the meter are probably coming in from the bottom (since we have underground lines) and are hidden. And I guess it also makes sense that the main breaker would be on the house side of the meter...not on the PG&E side. I think the big, unshielded silver wire also made me think the visible wires were coming in from the street because I was thinking that was the wire that is used to give the bundle strength when it gets pulled on to go through a conduit...but I guess the wires inside also need to go through a conduit and would need a wire like that anyway. Thanks for helping me to understand that.
So then I guess that means that the 100A breaker on those wires is there to shut off power to the house if we ever try to pull more than 100A into the house.
So I think what I probably want to ask Tesla to do is to add another panel, right off the meter as a new "main" panel, and also in that new main panel, put a 100A breaker that goes to my old main panel which make the old main panel just a "sub panel" going forward. Then I can put things like a faster EV charger or other high amperage devices in the new main panel since the old main was maxed out already. Am I thinking about this correctly? And is that what you did @Eric99 ?
What i would do is order your system and when they come out for the site survey, let them know that you need another panel for more space. They will make note of that. When they submit the plan for permits, ask for a copy of it. If its included, it will be listed. If its not, contact your advisor to have it changed. I have a feeling they dont deviate much from their set plan and this was the original intent regardless of me asking.
jgleigh
Member
Correct. The big aluminum wire looks like a ground. It's probably connected in the sub-panel in your garage.
Ok, I talked to PG&E again, and they again said that I can put a new breaker "up to a 319A"...the guy even said that our meter wouldn't even need to be upgraded...it's ready for 319A. So I'm starting to believe them 
So if that's possible, I'd like some advice on what I'm thinking of asking Tesla to do...
What I would like to achieve is this: use the grid (to import power) as little as possible (but still export as much as possible). I want to use my solar during the day to run the house and charge the powerwalls, then use the powerwalls in the evening to power the house. I would most likely try to charge the car only during sunny hours when the PWs are full (or filling) and the solar is producing way more than needed for the house so as not to drain the PWs.
Please let me know if I'm way off in my understanding of this stuff...I drew up these diagrams myself.
Here's what I currently have:
And here's what I think I would like to have:
Does this setup look possible? And does it look logical/desirable? Or am I missing something and should set it up some other way? Any advice or suggestions are welcome! I'm trying to learn all this as fast as I can.
Note: my existing panel is pretty much maxed out (the load calcs say it's at 98A and the box says the busbars can only handle 125A anyway)...so that's part of why I want a new panel -- to be able to put in a faster charger and to have room to add other things in the future (like a heat pump, electric water heater, etc).
So if that's possible, I'd like some advice on what I'm thinking of asking Tesla to do...
What I would like to achieve is this: use the grid (to import power) as little as possible (but still export as much as possible). I want to use my solar during the day to run the house and charge the powerwalls, then use the powerwalls in the evening to power the house. I would most likely try to charge the car only during sunny hours when the PWs are full (or filling) and the solar is producing way more than needed for the house so as not to drain the PWs.
Please let me know if I'm way off in my understanding of this stuff...I drew up these diagrams myself.
Here's what I currently have:
And here's what I think I would like to have:
Does this setup look possible? And does it look logical/desirable? Or am I missing something and should set it up some other way? Any advice or suggestions are welcome! I'm trying to learn all this as fast as I can.
Note: my existing panel is pretty much maxed out (the load calcs say it's at 98A and the box says the busbars can only handle 125A anyway)...so that's part of why I want a new panel -- to be able to put in a faster charger and to have room to add other things in the future (like a heat pump, electric water heater, etc).
CrazyRabbit
Active Member
Disagree, Tesla explicitly says to include the HPWC on the backup side, since the PW system has control over Tesla charging.
I assume this sets up future customers for V2G, so if that ever happens you do not need to re-wire your home. Even 1 powerwall can backup a Tesla HPWC.
Practically, I agree it is silly with the current implementation to recharge a large battery with a tiny battery. I am hopeful that eventually, this might go both ways but who knows the future.
Yeah, I’m going to try to avoid charging the car off the PWs whenever possible. I’m planning on just charging the car from any excess solar once the PWs are filled up. But it would be nice to be on the backup side in case I ever need to get a little juice from the PWs in a desperate situation…and I want to be able to charge from solar during an outage too. In fact, our power is out right now
@Vines thanks for your input too! I really appreciate it. Does my setup in the pictures above look/seem logical? And, would that be considered a “main panel upgrade”? Or is that a standard setup that Tesla does all the time? It doesn’t seem like it should cost much extra at all to do that setup…if it costs anything extra at all. But I hear people say that a MPU can be like $4000 :/
jgleigh
Member
Only issue is that you can only put 200A behind the Gateway. If you need more than 200A of calculated load, then you'll have to put the additional loads on the grid side of the Gateway. They can still pull from the batteries, but they won't be backed up when the grid is down.
Unless you set up a fairly complicated solution with a transfer switch that moves the additional loads from being grid supplied to being supplied behind the Gateway, without their load current ever actually passing through the Gateway.
Cheers, Wayne
I'm still wondering if I'm understanding things right...all the block diagrams I see have the grid coming into the gateway, and then there's a line from the gateway to the main panel...and that's it for that side. Then, the battery and solar both go into the main panel from the otherside...not interacting with the gateway at all...
Like this:
But it seems to me like all the power sources (solar, pw and grid) should all be going into the gateway, and then the gateway decides which source to use (or which sources to combine) to go into the house's main panel to run the home loads (like I drew in the picture above). Isn't that why it's named the "gateway"??
Am I missing something?
Like this:
But it seems to me like all the power sources (solar, pw and grid) should all be going into the gateway, and then the gateway decides which source to use (or which sources to combine) to go into the house's main panel to run the home loads (like I drew in the picture above). Isn't that why it's named the "gateway"??
Am I missing something?
jgleigh
Member
You're thinking about it correctly. That picture is overly simplified. The Powerwall and Inverter will connect to the Gateway. The Gateway decides if the Powerwall is charging or discharging and if the grid is connected or disconnected. Generally power will flow where it is needed.
The Gateway reads all power sources and all demand through CT measurement.
If you generate power at any point in the backup system, the TEG knows its magnitude in real time. So even if your solar was on a detached garage and the GW2 was on the main house, as long as the metering was done properly you could feed power in anywhere allowed by code.
This is also true of the ESS, they can inject current anywhere in the system downstream of the TEG. Then the meters inside each generation equipment all coordinate to aggregate the magnitude of the total PV and ESS generation and total demand of the home.
As far as your diagram above, you are only allowed to pass 200A through the TEG.
Ok good, thanks @jgleigh and @Vines! I was trying to reconcile that "wiring diagram" from Tesla with what I thought would actually be logical. It sounds like the gateway really is the brains of the operation and decides how much power is needed from each source (and how to combine them if needed) to power the home loads (up to 200A).
And I'm assuming that the GW would always prioritize running your loads from the solar power first, then the PW (depending on the mode you set in the app) and then the grid last. Is that right?
Now my next question: would it ever make sense to get two powerwall+'s? And does Tesla ever do that? I would love to have more than 1 inverter (to have more mppts, to have a "backup" if one inverter dies, to avoid clipping around noon, etc). Or if I was to convince them to give me more than 1 inverter, would they just give me 1 PW+, 1 PW, and 1 extra 3.7kW inverter? I'm most likely getting either 11.2kW or 12kW of solar (haven't figured that out 100% yet).
Thanks guys (and girls) for all your help! This forum has been so much more helpful than the actual Tesla advisors who seem to need a little more understanding of things. One advisor even told me "you can't charge your car off of solar...only the grid has enough power to charge a Tesla". Unless I'm really misunderstanding something, I'm pretty sure the solar panels could always charge the car as long as they're producing more power than the car is trying to pull (like if the solar is producing 8kW, you should be able to easily charge at 4kW right from the panels as long as the solar stays above 4kW -- assuming you're not trying to charge the PWs or pull a ton of load in the house).
from Tesla with what I thought would actually be logical. It sounds like the gateway really is the brains of the operation and decides how much power is needed from each source (and how to combine them if needed) to power the home loads (up to 200A).And I'm assuming that the GW would always prioritize running your loads from the solar power first, then the PW (depending on the mode you set in the app) and then the grid last. Is that right?
Now my next question: would it ever make sense to get two powerwall+'s? And does Tesla ever do that? I would love to have more than 1 inverter (to have more mppts, to have a "backup" if one inverter dies, to avoid clipping around noon, etc). Or if I was to convince them to give me more than 1 inverter, would they just give me 1 PW+, 1 PW, and 1 extra 3.7kW inverter? I'm most likely getting either 11.2kW or 12kW of solar (haven't figured that out 100% yet).
Thanks guys (and girls) for all your help! This forum has been so much more helpful than the actual Tesla advisors who seem to need a little more understanding of things. One advisor even told me "you can't charge your car off of solar...only the grid has enough power to charge a Tesla". Unless I'm really misunderstanding something, I'm pretty sure the solar panels could always charge the car as long as they're producing more power than the car is trying to pull (like if the solar is producing 8kW, you should be able to easily charge at 4kW right from the panels as long as the solar stays above 4kW -- assuming you're not trying to charge the PWs or pull a ton of load in the house).
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For me I wanted the number of Powerwalls need to meet most daily needs and power the home in an outage. It turns out so far we need 2. We have A/C and gas heating, so in a grid outage would only have large draws during the summer and fall. In winter we do not generate enough power to fully charge the Powerwalls every day, but only need about 50% to cover our needs because of gas heating.Ok good, thanks @jgleigh and @Vines! I was trying to reconcile that "wiring diagram"
And I'm assuming that the GW would always prioritize running your loads from the solar power first, then the PW (depending on the mode you set in the app) and then the grid last. Is that right?
Now my next question: would it ever make sense to get two powerwall+'s? And does Tesla ever do that? I would love to have more than 1 inverter (to have more mppts, to have a "backup" if one inverter dies, to avoid clipping around noon, etc). Or if I was to convince them to give me more than 1 inverter, would they just give me 1 PW+, 1 PW, and 1 extra 3.8kW inverter? I'm most likely getting either 11.2kW or 12kW of solar (haven't figured that out 100% yet).
Thanks guys (and girls) for all your help! This forum has been so much more helpful than the actual Tesla advisors who seem to need a little more understanding of things. One advisor even told me "you can't charge your car off of solar...only the grid has enough power to charge a Tesla". Unless I'm really misunderstanding something, I'm pretty sure the solar panels could always charge the car as long as they're producing more power than the car is trying to pull (like if the solar is producing 8kW, you should be able to easily charge at 4kW right from the panels as long as the solar stays above 4kW -- assuming you're not trying to charge the PWs or pull a ton of load in the house).
Regarding charging the car off solar, the rep may be right if your load is charging (10 kW or so for 40 A for charging, more at your proposed 48A) + Air Conditioning load (5+ kW). You can get 7 kW max continuous from each Powerwall+. I assume the rep is trying to not get into an over promise situation and offering a conservative opinion.
But since you have a Tesla Powerwalls and charger, there is a setting in the app where you can specify the lower limit percentage you expect in the Powerwalls to charge the car. This will ensure vehicle charging does not deplete your Powerwalls too far when the grid is down.
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jgleigh
Member
Correct. Solar will always go to loads first and then batteries and then grid. Cars will look like an additional home load and can be manually controlled or prioritized behind batteries using some third-party tools. Obviously battery modes in the app can affect all of this.
I have two Powerwall+ and two Powerwall 2 in my system. But I have a 16.3kW array so needed two inverters regardless.
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