Utility Transformer Upgrade - Burden of Cost?

[x10Corey]

After almost a year of trying to get solar installed I thought we were at the finish line until I got CC'd on an email from my utility company.

The capacity of your photovoltaic (PV) plus battery (BT) project exceeds the rating of the 15 kVA transformer serving your residence.

The email stated I had 2 weeks to respond with whether I'm requesting a quote or downgrading the system, so I responded right away for a quote request. It took two weeks but I just received it from them at $2,100. Luckily the utility CC'd me because I have heard nothing from Tesla regarding this and the two week deadline was today to respond... not really surprised with how bad they've been up until now.

My question is, will Tesla pay or chip in for this upgrade? I found a single blog post where the person was able to get Tesla to pay but it's from 2018. (My Solar Power Odyssey with Tesla and National Grid - Bettnet.com)

Has anyone here heard of or had recent experience regarding utility upgrades? At this point I'll probably just shell out the money as I'm at the end of my patience dealing with Tesla regarding the project. Thought I'd check in here first though.

Thanks!

 

[MorrisonHiker]

I'd consider yourself lucky if it's only $2100. Our power company quoted us $15000 to upgrade the transformer serving our house as well as 4 other houses. They had already been in the process of replacing all power poles and many transformers in town after a recent storm but they stopped the process of replacing the two poles leading to our house after having already used a hydrovac to excavate holes. They covered the 8 foot deep holes with plywood and orange cones and then came back a few weeks later and filled the holes in.

 

[nwdiver]

After almost a year of trying to get solar installed I thought we were at the finish line until I got CC'd on an email from my utility company.


The email stated I had 2 weeks to respond with whether I'm requesting a quote or downgrading the system, so I responded right away for a quote request. It took two weeks but I just received it from them at $2,100. Luckily the utility CC'd me because I have heard nothing from Tesla regarding this and the two week deadline was today to respond... not really surprised with how bad they've been up until now.

My question is, will Tesla pay or chip in for this upgrade? I found a single blog post where the person was able to get Tesla to pay but it's from 2018. (My Solar Power Odyssey with Tesla and National Grid - Bettnet.com)

Has anyone here heard of or had recent experience regarding utility upgrades? At this point I'll probably just shell out the money as I'm at the end of my patience dealing with Tesla regarding the project. Thought I'd check in here first though.

Thanks!

Apologies if I missed it... how big is your PV system? I don't see why the batteries would be relevant at all.

 

[BGbreeder]

$2,100 for an upgraded transformer is a great price in my book. I wouldn't think twice about it.

All the best,

BG

 

[zƬesla]

Our solar installer picked up the utility upgrade cost of $800 from a 10 to 25 transformer when we installed solar earlier this year. I’m sure it came out of the variable “site work” budget but at least it wasn’t an extra add on for us.

 

[x10Corey]

Apologies if I missed it... how big is your PV system? I don't see why the batteries would be relevant at all.

It's a 21.42 kW System with 3 Powerwalls. I'm in New Hampshire with Eversource for my utility company.

Seems like the consensus is to just pay for it, I'll mention it to Tesla but won't push for it if they deny. Thanks for the feedback!

 

[nwdiver]

It's a 21.42 kW System with 3 Powerwalls. I'm in New Hampshire with Eversource for my utility company.

Seems like the consensus is to just pay for it, I'll mention it to Tesla but won't push for it if they deny. Thanks for the feedback!

Do you know what the AC rating is? You could file a complaint with the utility commission or whatever public service body you guys have up there. If the AC rating is ~15kW that's just silly to upgrade the transformer.

Transformer ratings are weird. Utilities play fast and loose A LOT with kW ratings on their equipment. I have a friend with 400A service and a 25kVA transformer. I charged at a RV park once that had 4 50A spaces and it was connected to a 10kVA transformer.

 

[x10Corey]

Do you know what the AC rating is? You could file a complaint with the utility commission or whatever public service body you guys have up there. If the AC rating is ~15kW that's just silly to upgrade the transformer.

Transformer ratings are weird. Utilities play fast and loose A LOT with kW ratings on their equipment. I have a friend with 400A service and a 25kVA transformer. I charged at a RV park once that had 4 50A spaces and it was connected to a 10kVA transformer.

Would it be in my docs section? Looking at the interconnect app it says 36.4kW facility (Max AC Rating) talking about my house. I have a 200A service. The only thing I can find mentioning the transformer was the email they sent saying it has a max of 15 kVA.

 

[nwdiver]

Would it be in my docs section?

Should be; What inverter(s) is Tesla proposing? For example, I installed a 22.77kW system with (2) 7.7kW inverters so the AC rating is 15.4kW. That's the number that matters for the transformer, not the 22.77kW DC rating.

 

[zƬesla]

@x10Corey I'm also in NH (and install referenced above was for NH home). The one thing my PV installer indicated was that if I could show that the transformer at the pole was undersized for the current home(s) usage, Eversource would need to put in the new one at their own dime. For example, if the homes installed A/C units after the transformer was in place and together had a larger rating.

 

[nwdiver]

@x10Corey I'm also in NH (and install referenced above was for NH home). The one thing my PV installer indicated was that if I could show that the transformer at the pole was undersized for the current home(s) usage, Eversource would need to put in the new one at their own dime. For example, if the homes installed A/C units after the transformer was in place and together had a larger rating.

Yeah... that's odd to me to force someone on a residential service schedule to pay for their transformers. I believe the way it works here under Xcel is Xcel pays for the equipment required to provide the service you want. If you want to be under a residential rate Xcel provides you with 240v and they pay to provide 240v. If you want cheaper 'wholesale' rates you can take 115kV but you're on the hook for the equipment required to make 480, 208, 240 or whatever...

 

[MP3Mike]

Yeah... that's odd to me to force someone on a residential service schedule to pay for their transformers. I believe the way it works here under Xcel is Xcel pays for the equipment required to provide the service you want. If you want to be under a residential rate Xcel provides you with 240v and they pay to provide 240v. If you want cheaper 'wholesale' rates you can take 115kV but you're on the hook for the equipment required to make 480, 208, 240 or whatever...

If it makes sense for the utility to pay for the infrastructure necessary to sell you power. Doesn't it make sense that you should have to pay for the extra infrastructure necessary for you to sell them power?

 

[x10Corey]

Should be; What inverter(s) is Tesla proposing? For example, I installed a 22.77kW system with (2) 7.7kW inverters so the AC rating is 15.4kW. That's the number that matters for the transformer, not the 22.77kW DC rating.

Here's a screen shot from the drawings page:
2020-08-15_16-35-49

Looks like two inverters
1: SolarEdge SE10000H-US 11,400W
2: SolarEdge SE7600H-US 7,600W

I emailed the generic Tesla energy address asking about it since the phones are closed on weekends, also asked about the dedicated advisor that I saw in another post. I would love to have one of those!

@x10Corey I'm also in NH (and install referenced above was for NH home). The one thing my PV installer indicated was that if I could show that the transformer at the pole was undersized for the current home(s) usage, Eversource would need to put in the new one at their own dime. For example, if the homes installed A/C units after the transformer was in place and together had a larger rating.

I rarely see people from NH online, I thought no one else in the state used the internet! I'm not sure how to go about showing the usage for any other house besides mine. I'm on the corner of my road and a cross road, the street I'm on has probably 30 or so houses on it and the development was built in 99-00 so about 20 years ago.

 

[SalisburySam]

When we bought our home, the electricity came from a power pole near the corner of our lot. The wires draped from there about 1 foot over our garage roof to a pole in the center of our backyard. From there to the house. We weren’t fans of the pole-in-the-middle-of-the-yard so we wanted to take it out as a part of the much larger overall electrical re-do for this 1906 house. We paid to trench from the actual power pole to our home, about 80 feet of 42”-deep trench across our concrete driveway, and while we were at it upgraded power to 400amps to the house, split to two 200-amp load centers, one further divided down to 100-amps that separately fed back to our detached garage. This was more than the utility company said could be handled by the existing transformer so they replaced it...totally their cost. Everything else (trenching, wires, load centers, labor, 4” conduit) was my cost. I don’t know what size the original transformer was or the size of the new one they replaced it with, but it works very well.

As an aside it was very interesting watching the pro’s feed 3 very large and stiff wires through the conduit (lots and lots of grease, both elbow and petroleum-based), and later replace the transformer. Very informative watching someone who knows exceedingly well what she’s doing make those pole-top disconnects and final connects inches from an uninsulated high-voltage line.

 

[CrazyRabbit]

How does the power company get away with undersizing transformers? There has to be some logic behind this.
My 100KVA transformers feed 4 houses, all with 320A service. That is 104A, or 25KVA per house.

 

[nwdiver]

How does the power company get away with undersizing transformers? There has to be some logic behind this.
My 100KVA transformers feed 4 houses, all with 320A service. That is 104A, or 25KVA per house.

The losses are on their side of the meter. So I think it's just a cost-benefit thing. If they save $2k on a smaller transformer but convert $1500 worth if kWh into heat over a 15 year period then they'll 'undersize' the transformer. I happened to have an IR camera with me when I charged at the RV park with 200A (~48kVA) of plugs on a 10kVA transformer. The transformer was ~120F on a cold winter night...

 

[JeremyWhaling]

From an earlier discussion: Transformers are one of the few electrical components that can be somewhat overloaded without issue, as long as it is cooled off in the night or lower load period.

Of course, sustained overload can (at minimum) shorten the life of the transformer or cause failure (sometimes spectacularly).

 

[SMAlset]

When we bought our home, the electricity came from a power pole near the corner of our lot. The wires draped from there about 1 foot over our garage roof to a pole in the center of our backyard. From there to the house. We weren’t fans of the pole-in-the-middle-of-the-yard so we wanted to take it out as a part of the much larger overall electrical re-do for this 1906 house. We paid to trench from the actual power pole to our home, about 80 feet of 42”-deep trench across our concrete driveway, and while we were at it upgraded power to 400amps to the house, split to two 200-amp load centers, one further divided down to 100-amps that separately fed back to our detached garage. This was more than the utility company said could be handled by the existing transformer so they replaced it...totally their cost. Everything else (trenching, wires, load centers, labor, 4” conduit) was my cost. I don’t know what size the original transformer was or the size of the new one they replaced it with, but it works very well.

As an aside it was very interesting watching the pro’s feed 3 very large and stiff wires through the conduit (lots and lots of grease, both elbow and petroleum-based), and later replace the transformer. Very informative watching someone who knows exceedingly well what she’s doing make those pole-top disconnects and final connects inches from an uninsulated high-voltage line.

Line workers are some of the best people out there. Super dangerous job in all kinds of weather. Hate to think where we’d be if there was a mass retirement and not enough workers to replace them.

 

[nwdiver]

From an earlier discussion: Transformers are one of the few electrical components that can be somewhat overloaded without issue, as long as it is cooled off in the night or lower load period.

I found this handy guide for XFMR sizing;

 

[zƬesla]

I rarely see people from NH online, I thought no one else in the state used the internet! I'm not sure how to go about showing the usage for any other house besides mine. I'm on the corner of my road and a cross road, the street I'm on has probably 30 or so houses on it and the development was built in 99-00 so about 20 years ago.

How many houses are on the same transformer? Take your usage and multiply it by that number for a general estimate. If it’s more than the # on transformer you may have a case.