Will I need a panel upgrade?

[cwied]

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?

It depends on the mode you select. If you select "Time-Based Control" mode, the gateway prioritizes the PW over load during off-peak. It then switches to prioritizing the grid over loads during partial and full peak (presuming that it was able to charge enough to cover both partial peak and full peak) in order to maximize NEM credits. If there isn't enough sun to charge to cover full peak, it'll charge during partial peak to hit that level and then go idle until full peak.

On the other hand, if you select "Self-Powered," it will operate as you say. It will try never to use grid energy, so during the day solar will go to your loads first then to the battery. If your loads exceed solar production, the battery will discharge to make up the difference until it hits the backup reserve you configured.

 

[paladaxar]

I'm still trying to get Tesla to do this upgrade...

For a recap, right now, I have a 100A meter main and I'm trying to get Tesla to upgrade that breaker to 200A (pictures of everything above). I already contacted PG&E and they said that we could install "up to a 319A breaker".

Tesla is saying that upgrading that 100A breaker would still be considered a "main panel upgrade" because they would have to upgrade the bus bars, etc...and since the site surveyor didn't say that it need to be upgraded, they're not going to do it. I responded that I didn't think there were any busbars that needed to be upgraded since it's just a single breaker.

In my estimation, the upgrade should be fairly simple...just swap out the 100A breaker that's next to the meter with a 200A breaker and then from the new 200A breaker, run a couple feet of wire to the gateway. Then, inside the gateway, put a new 100A breaker on the line that feeds my old whole home load panel to protect it from drawing more than 100A. Done.

I've given up on trying to get them to add another sub panel for me, but at least this setup (a new 200A breaker next to the meter) should then allow me in the future to swap that new 100A breaker in the gateway for a 200A breaker, then add a new 200A subpanel between the gateway and the old subpanel with one 100A breaker in it feeding the old sub panel. That would then give me a whole 100A more expansion potential (since my current load calcs come to about 98A so I can't add any new circuits).

I'm not sure why Tesla is pushing back on this so hard. Am I missing something? Is this really still considered an MPU since it's just one breaker? I thought and MPU was expensive and time consuming because it includes disconnecting every breaker used by the house and reconnecting them in a new breaker. It seems like this breaker swap should be relatively quick/easy while they're doing so much electrical work already. Or, does Tesla have to get PG&E involved if they change the breaker next to the meter and they're trying to avoid that? Or, does Tesla always contract out that work and they're trying to avoid getting another contractor involved unless absolutely necessary (to not slow things down or add more cost)? It seems to me like it should add maybe $500 max to the job and I'd be glad to pay that rather than start a whole new process with an electrician later with all new permits, etc. But like I said, maybe I'm missing something. Any insights are welcome!

I'm getting close to throwing in the towel on trying to get them to do this upgrade. It would be nice to get this done at the same time that the solar and PWs go in, but I may just need to do it down the road. Has anyone done this upgrade before or after their solar/pw installation? And if so, about how much did it cost when done on its own?

 

[BGbreeder]

My $0.02? Pause Tesla, do the panel upgrade that you want, then let Tesla know you have an altered electrical arrangement, and start over. Or just go with a third party.

Getting an electrician to touch panels after a Tesla installation is going to be extremely difficult. Why? Well, there will be a variety of warning stickers on the panel, saying amongst other things, "no additional loads". A reasonable electrician is likely conclude that he/she does not want the liability for mucking around with Tesla's wiring, and any future failures. That leaves the clueless, and the risk takers. Do you really want a clueless, or risk loving electrician to do your wiring?

All the best,

BG

 

[paladaxar]

My $0.02? Pause Tesla, do the panel upgrade that you want, then let Tesla know you have an altered electrical arrangement, and start over. Or just go with a third party.

Thanks for your $.02. If I had more time, that's probably what I would do. My limiting factor right now is that I have some really good financing locked in (3% with no down payment) that expires in early October. Tesla has already set up an installation date in late September...so I'm hesitant to thrown a wrench in the works that could delay things.

Sounds like it could be a pain though to upgrade later :/ I'm not sure what to do.

 

[Vines]

I'm still trying to get Tesla to do this upgrade...

For a recap, right now, I have a 100A meter main and I'm trying to get Tesla to upgrade that breaker to 200A (pictures of everything above). I already contacted PG&E and they said that we could install "up to a 319A breaker".

Tesla is saying that upgrading that 100A breaker would still be considered a "main panel upgrade" because they would have to upgrade the bus bars, etc...and since the site surveyor didn't say that it need to be upgraded, they're not going to do it. I responded that I didn't think there were any busbars that needed to be upgraded since it's just a single breaker.

In my estimation, the upgrade should be fairly simple...just swap out the 100A breaker that's next to the meter with a 200A breaker and then from the new 200A breaker, run a couple feet of wire to the gateway. Then, inside the gateway, put a new 100A breaker on the line that feeds my old whole home load panel to protect it from drawing more than 100A. Done.

I've given up on trying to get them to add another sub panel for me, but at least this setup (a new 200A breaker next to the meter) should then allow me in the future to swap that new 100A breaker in the gateway for a 200A breaker, then add a new 200A subpanel between the gateway and the old subpanel with one 100A breaker in it feeding the old sub panel. That would then give me a whole 100A more expansion potential (since my current load calcs come to about 98A so I can't add any new circuits).

I'm not sure why Tesla is pushing back on this so hard. Am I missing something? Is this really still considered an MPU since it's just one breaker? I thought and MPU was expensive and time consuming because it includes disconnecting every breaker used by the house and reconnecting them in a new breaker. It seems like this breaker swap should be relatively quick/easy while they're doing so much electrical work already. Or, does Tesla have to get PG&E involved if they change the breaker next to the meter and they're trying to avoid that? Or, does Tesla always contract out that work and they're trying to avoid getting another contractor involved unless absolutely necessary (to not slow things down or add more cost)? It seems to me like it should add maybe $500 max to the job and I'd be glad to pay that rather than start a whole new process with an electrician later with all new permits, etc. But like I said, maybe I'm missing something. Any insights are welcome!

I'm getting close to throwing in the towel on trying to get them to do this upgrade. It would be nice to get this done at the same time that the solar and PWs go in, but I may just need to do it down the road. Has anyone done this upgrade before or after their solar/pw installation? And if so, about how much did it cost when done on its own?

The physical panel you have will not take anything larger than the 100A breaker inside it, unless it says otherwise. Since there is no sticker, it's likely a 100A enclosure with a 100A breaker. To install a new 200A meter main combo panel there is a lot of work to do even without relocating dozens of circuits.
1. Disconnect/reconnect with PGE
2. Replace the service conductors (trench and transformer upgrade as needed at extra cost)
3. Physically remove the box from the wall.
4. Break open the wall to install the new service enclosure, patch the siding/stucco, paint and waterproof it.
5. Verify all this with PGE, the city and get it signed off.

This work is typically in the range of $4-5k. Prices on everything are going up, so waiting isn't likely better either.

Tesla likes their process and it drives the pricing. If you are trying to get something out of the box from Tesla it will often be a struggle.

Unless you are really well connected and knowledgable, try to have a single entity be responsible for the whole job you intend on doing. Tesla prices mean you have to deal with Tesla processes. I understand service upgrades to be a bit of a wait right now.

You may find another electrician willing to do the service upgrade, as long as he doesn't have to touch Tesla equipment. I doubt they will be much faster right now, as many electrical contractors are very busy with other work.

Where I work, our backlog is getting into the 6-month range right now and we have hired a lot lately to try and keep up. These skills of installing PV and ESS are not common and so getting really qualified reliable people is a challenge.

 

[jjrandorin]

Sounds like it could be a pain though to upgrade later

Its likely to be either "very difficult", or "virtually impossible" to upgrade your electrical system "later". In order to do it later, you might have to have buy another PV system and have that company do it.

Making any changes (like any changes) after you do PV + powerwalls is difficult. Your solar installer might do it, but if its Tesla, they are not interested in that work. The red stickers everywhere mean no one else is going to want to touch it.

You would be better off doing the main panel upgrade like @BGbreeder said. Losing your financing would likely be less impactful than not being able to add anything to your home electrical for years.

(personal opinion only, no inside information implied).

 

[paladaxar]

The physical panel you have will not take anything larger than the 100A breaker inside it, unless it says otherwise.

Oh man, I didn’t realize that these boxes were limited in the breaker size they can take. I know the boxes with the bus bars are limited (I’m guessing because the bus can only handle so much current).

But aren’t these meter/main panels just a meter, wires and a circuit breaker? There’s no need for a bus bar, right? There are no other breakers in the box and no place to even add any.

So I was thinking that all they would have to do is upgrade like 4 inches of wiring from the meter to the breaker, then about 2-4 feet of wire from the breaker to the gateway. Is there a reason why the box itself “can’t handle more than 100A”?

Here’s a picture of the meter and the outside of the box if it helps…

At least the meter seems to be set up for 200A already (I saw somewhere that CL200 means “class 200A”).

And the inside again…

 

[Vines]

Oh man, I didn’t realize that these boxes were limited in the breaker size they can take. I know the boxes with the bus bars are limited (I’m guessing because the bus can only handle so much current).

But aren’t these meter/main panels just a meter, wires and a circuit breaker? There’s no need for a bus bar, right? There are no other breakers in the box and no place to even add any.

So I was thinking that all they would have to do is upgrade like 4 inches of wiring from the meter to the breaker, then about 2-4 feet of wire from the breaker to the gateway. Is there a reason why the box itself “can’t handle more than 100A”?

Here’s a picture of the meter and the outside of the box if it helps…

View attachment 844390

At least the meter seems to be set up for 200A already (I saw somewhere that CL200 means “class 200A”).

And the inside again…
View attachment 844393

What you said sounds great, and is totally not how it works.

The metal box and breaker location and mounting is sized per the largest conductor bend radius. The conductors, breaker and hardware from the utility side to the breaker are all considered part of a listed assembly. There is no replacing any parts inside your panel (unless repaired with factory parts like a replacement busbar) where it costs you significantly less than I outlined above, and is code compliant. Also every panel has a sticker on the inside lid, which tells you exactly what you can and can't do with the panel. I do not see that your sticker is there, but it might just not be visible.

I am pretty confident that a 200A main breaker is not going inside there in any kind of code legal way in San Jose, for significantly less than I outlined above.

 

[paladaxar]

What you said sounds great, and is totally not how it works.

The metal box and breaker location and mounting is sized per the largest conductor bend radius. The conductors, breaker and hardware from the utility side to the breaker are all considered part of a listed assembly. There is no replacing any parts inside your panel (unless repaired with factory parts like a replacement busbar) where it costs you significantly less than I outlined above, and is code compliant. Also every panel has a sticker on the inside lid, which tells you exactly what you can and can't do with the panel. I do not see that your sticker is there, but it might just not be visible.

I am pretty confident that a 200A main breaker is not going inside there in any kind of code legal way in San Jose, for significantly less than I outlined above.

Bummer Good call on the bend radius of the wires…I hadn’t thought about that factor. So is it true that there are no bus bars in these types of meter/main boxes? And yeah, there’s no sticker any more.

It sounds like even if I want to pay to have it done (and I do), they don’t seem to want to do it. Do they usually contract out this work? And would PG&E have to get involved? I wonder if they don’t want to do it because it would drag out the timeline for the project and they just want as quick of a turnover as possible.

 

[BGbreeder]

TL-DR: Observationally, Tesla = cookie cutter.

They draw up their plans and that's what they want to build, and are willing to build. Sized down, sized up (a little depending on roof area/design) is about all they will do, and only with prodding from the customer. It is their schtick/business model. I can't fault it, as it seems to work for them. Having a cookie cutter saves time, costs, and probably lowers the demands in their installation crews because everything is standardized.

You aren't the first to want something more from Tesla, nor, I am sure, will you be the last. There are a slew of posts here to the effect of "Help! Tesla won't do what I want." Other than a few cases where the owner brought an oversight to their attention, I haven't seen any wins in the homeowner column.

Personally, I think that you are doing the sensible thing and installing for a larger main panel that will give you more flexibility in the future. The clear trend is toward more electrical power usage in homes. Since Tesla doesn't want to do a main panel at your home, for whatever reason, I think that you need to find someone else to do the main panel upgrade, and potentially the whole project. If you go with Tesla, and don't do a main panel upgrade and then at some point in the future need a new panel, I suspect that you might want consider that the additional cost is a main panel replacement in a Tesla system in the future is likely going to be more than any potential savings on the financing terms.

But who knows? Perhaps an electrical contractor may decide to specialize in upgrading Tesla main service panels. I just don't see their services as likely to be anything other than expensive, and I think, for good reasons.

All the best,

BG

 

[Vines]

Bummer Good call on the bend radius of the wires…I hadn’t thought about that factor. So is it true that there are no bus bars in these types of meter/main boxes? And yeah, there’s no sticker any more.

It sounds like even if I want to pay to have it done (and I do), they don’t seem to want to do it. Do they usually contract out this work? And would PG&E have to get involved? I wonder if they don’t want to do it because it would drag out the timeline for the project and they just want as quick of a turnover as possible.

Different panels have a busbar or not, which is where a breaker or breakers can attach. Often times there is wire from the PGE side meter connection to the customer side main breaker connection. Regardless it is all listed equipment and so you cannot substitute other parts here.

They do contract this work from my understanding, and it might take 6 months (or longer) to get the service swap completed. PGE absolutely has to be involved, and there is the possibility of a transformer upgrade. If you have an overhead service the service drop conductors are easy to replace but if you have a underground run then it is quite expensive to upgrade.

I am not sure what sort of questions you asked PGE to get your 319A answer, but when I did my service upgrade, PGE took many months to give us the answer that we could upgrade from a 200A to a 400A service and that it would not cost a transformer upgrade. We paid PGE $1500 to do this evaluation, and they refunded us a large portion when they hadn't spent it all. If we had to do a transformer upgrade, the leftovers of the $1500 would have been applied there.

Only they know why they are resistant to the service upgrade, but timing is likely part of it. You could ask them why, I'd be curious as to what they say.

 

[paladaxar]

Thanks for all the replies everyone, that all helps a ton. I felt like I was going at it alone against Tesla (not that I’m against them) and I wasn’t sure if I was wrong or they were wrong…but it sounds like maybe a little of both. All this extra support and education from you guys has helped a ton with my understanding and what I should push for and what to expect.

 

[Eric33432]

I have found this thread very interesting, and I would like to chime in on this, and am curious if you have come to any decision.

1. You have what is called a "meter main. Here is what they look like inside. This one is 200 amps. Yours is very likely only rated for a 100 amp breaker. A 200 amp breaker would be much larger and not fit in your box.

2. Just because the meter has a CL200 rating does not make your meter main capable of 200 amps

3. I have a hard time believing your POCO installed wire good for 319 amps to your meter. You need to have someone open the meter and verify.

4. I have seen 200 amp service here with #2 AL wire coming from the POCO. They size the wire for the expected load and voltage drop, not for 200 amps. A typical example would be a 2000 s.f. house with a 4 ton air conditoner with 10 KW of electric heat. I have also seen 200 amp services with 4/0 AL wire on a larger houses with, say (2) air conditioners and 20,000 KW of electric heat.

5. Then there is the transformer to which your house is connected to consider.

6. Replacing a meter main in my area would cost about $3,000 to $4,000 if you use a typical small business electrician, more if you use one of those large electrical contractors. Replacing underground service wires by the POCO would be extra, replacing the overhead wire in my area would not cost much or maybe cost nothing. In my area the POCO would upgrade the transformer, if needed, at no additional cost. The one serving my house and 2 of my neighbors was upgraded from 50 kVa to 75 kVa about a year ago.

7. I cannot imagine Tesla or any other solar company would replace your meter main at no cost. They quoted adding solar to your existing electrical system and upgrading the meter main is beyond the scope of their job.

8. But why Tesla would not want to make an upgrade part of their installation, at whatever it would cost, I cannot understand, other than they are just so busy they might not want to fool with it.

9. If your load calculation comes to 98 amps right now, you would probably be best served to upgrade to 200 amps if you want to add electric water heater and a heat pump, along with unfettered EV charging, which requires backup electric heat which runs when defrosting the heat pump and is necessary to have available in case something goes wrong with the heat pump.

10. Even though your load calculation comes to 98 amps, you rarely use that much power. 98 amps running 24 hours a day would consume almost 17,000 kWh in a month! So if you do not want to upgrade your service (but you would probably not be able to add electric water heating or the heat pump) if you want to get by with the existing 100 amp service, there are devices that can monitor your home's power consumption, and if the consumption is too high will interrupt your EV charging, such as this device:

EVEMS - Electric Vehicle Energy Management Systems

Get faster electric vehicle charging without upgrading an existing electrical service or panel when installing an EV charger, by using Automatic Load Management Systems (EVEMS or ALMS) by Black Box Innovations.

shop.blackbox-in.com

and this device:

DCC Electric Vehicle (EV) Charging for Condos or Full Panel Homes

DCC Electric – DCC-10 EV charging hardware for a full electrical panel in a house. DCC-9 EV charging hardware for condos and apartments.

dccelectric.com

There are others. This would be "fettered" EV charging!

11. The Tesla Backup Gateway 2 is capable of being configured to be Service Equipment assuming your local POCO and AHJ will allow it. This would allow you to simply install a new 200 amp meter socket and feed the gateway direct from the meter, in which a 200 amp "main" circuit breaker would be installed. The Gateway would become the main disconnect. See page 25 of this manual:

https://www.tesla.com/sites/default/files/pdfs/powerwall/Powerwall_2_AC_GW2_NA_EN_Installation_Manual.pdf

This is how it would be wired:

12. I cannot imagine why Tesla would not want to install such a configuration. Initially it could be installed and fed from your 100 amp meter main, and later you could replace your meter main with just a new 200 amp rated meter socket (if allowed) or a 200 amp meter main (if required). Since your existing meter-main (and its replacement) is before all the Tesla stuff, you should be able to find an electrician who would do such a job. This should have been seen as an option when you had your site survey.

Let us all know what you end up getting, and good luck.

 

[paladaxar]

Wow thank you for that detailed reply @Eric33432 ! I really appreciate it. I’ve been working hard all day to try to get ready for installation day which is right around the corner. I’m still trying to digest everything you said and will probably respond more tomorrow or the next day.

I think it’s too late to make any changes to the plans before installation, but I wonder, when the installers come and I talk to them in person, how much they can deviate from the plans — and how much I could get them to set things up in the best way possible to allow me to upgrade later. It sounds like a good idea to ask them if they can put a 200A breaker in the GW2.

Is there anything else that would be a good idea to ask for on the day of installation? (Either to help me with upgrades later or just good things to have them do in general that they might not do without me asking) The worst they can do is say no.

 

[Eric33432]

I understand your desire not to do anything to delay your installation. So your installation will proceed with your existing 100 amp meter main ("MM") and your existing load center, presumably as follows:

A conduit and the wiring will need to be installed between your existing MM and the Backup Gateway 2 ("BG2") to feed power into the BG2 and the SER cable that attaches to your existing 100 amp breaker in your MM will need to be removed from the 100 amp breaker and connected to the Backup Lugs of the BG2, or perhaps new conduit and cable will be installed from the BG2 to your existing load center, depending on where the BG2 is installed.

I think the above will work fine (I assume it is working fine right now, and the load center appears to have been recently replaced and is presumably in good condition) however you will need to be careful with EV charging during a power outage, as two Powerwalls only hold 28 kWh of energy and charging an EV, even at 16 amps @ 240 volts will remove almost 4 kWh of energy from the Powerwalls each hour. (With a 20 amp circuit, EV charging should be limited to 80% of 20 amps which is 16 amps.)

Once your Tesla installation is complete, and if you want to add additional capacity, if this were my house, here is what I would do:

1. I would do a new load calculation, using Mike Holt's Electrical Tool Box app with the upgrades I want to install.

2. I would then verify that the POCO can support this with the wires and transformer that is installed. I say this because I find it hard to believe that the POCO would install wires capable of 319 amps to a house with a 98 amp load calculation. Before you proceed this needs to be verified beyond any doubt or you could be in for a very expensive surprise.

3. If the POCO cannot support everything you want, a decision will need to be made to upgrade (or not upgrade) the wires coming in to the meter, and I would re-run the load calculation without any EV charging, and if the wires are OK without any EV charging I would install the EV energy management equipment I referenced in my post yesterday. Personally, if it were me, and the cost to upgrade the wires is 10 or 15 k$, I would opt for the EV energy management equipment if it made the difference between being able to upgrade with the existing POCO wires or not.

4. If the POCO cannot support either of the above two situations, I would then have to decide if I want to upgrade the wires and/or transformer, or just leave the existing 100 amp system. In this situation, personally I would probably bite the bullet and do the upgrade if I was planning to stay in this house for more than, say 5 years (and it might make the house easier to sell too).

5. Assuming 2, 3, or 4 above are OK, I would install a 200 amp MM, with distribution, not just a new 200 amp meter as I discussed yesterday (reasons below).

6. I would connect EV charging equipment to breakers installed in the MM (reasons below).

7. I would leave the existing 20 amp @ 240 volt receptacle connected to the existing load center for emergency EV charging during a grid outage.

I will now discuss why I would install a MM with distribution:

With a MM with distribution, such as an Eaton CMBE88B200BTS which has space for 8 breakers/8 circuits or MBE2040B200BTS which has space for 20 breakers/40 circuits, you can easily install breakers for circuits that are not backed up such as EV charging equipment.

Keep in mind that electrically all devices are in parallel and connected unless there is a grid outage. Electrically there is no difference between a device connected to a MM before the BG2 and a device connected to the Backup Lugs of the BG2 as these are all solidly connected with large gauge wire during normal grid operation. So when the grid is providing power, your solar will provide power to any device connected to the MM distribution buss the same as if it is connected to the Backup Lugs of the BG2. The only difference is the device connected to the MM distribution buss will not be backed up in a power outage.

Therefore you do not need to worry about connecting everything to the Backup Lugs of your BG2, in fact if you try to run too much from two Powerwalls you will either drain them quickly or overload them. I believe you said you are getting two Powerwalls, so you need to be careful as two Powerwalls will hold only 28 kWh of energy, and as I mentioned above charging an EV (or two EVs!) during a grid failure could quickly drain them, and if a grid outage occurred while even one car was charging at full power of 11.5 kW it would probably overload them as they are only capable of providing 5 kW output power. For this reason, I would recommend connecting your EV equipment so that it is not backed up. But, again, that does not mean your solar system will not be providing power to your EVs.

Last, you should not necessarily charge EVs when the sun is shining. It depends on the rate structure of your POCO. It may, or may not, be cheaper to send power to the POCO during the day, and buy it back in the middle of the night. In my case, my 14.8 kW system will generate about 20,000 kWh of energy a year, and our MX and MY use about 7,000 kWh of energy a year, but our cars will rarely charge directly from the solar as I almost always them in the middle of the night.

I hope the above is helpful and if I have said anything that is not correct that others will correct me.

Good luck,

Eric in Boca Raton, Florida

 

[wwhitney]

I will now discuss why I would install a MM with distribution:

Because of the rules in NEC 705.12, it is much more flexible to install a meter main with a feeder to a separate main breaker distribution panel for non-backed up loads. Then that feeder can go on to supply the back up gateway, backed up loads, and generation panel.

Cheers, Wayne

 

[Eric33432]

Wayne, thanks for this. Something to definitely think about.

It will be interesting to see how Tesla does this install. Hope the OP posts updates with lots of pictures!!

Eric

 

[Michael Bornyk]

You could easily just use a Power Management System like Black Box Innovations. . Then you do not need to upgrade panel or service it will manage power for you.