Interconnection application help - One-line diagram issue

[BackCountry]

I don't see why a disconnect on both sides of the meter is necessary. It would be really stupid of the utility to require one on the load (solar) side of the meter if there is already one on the line (utility) side, but that's not to say utilities are never that stupid. The NEC only requires one fused disconnect. I guess if one is unsure how many total disconnects the utility requires, and if the goal is to avoid another round of back and forth on the interconnection app no matter the cost or ugliness of the installation, then resubmitting with two disconnects might be the choice.

I only see these rarely on older NGOM meters, where the ESS didn’t have PCS and PG&E required them.

In those instances they always require an upstream OCPD (fused disconnect) and an isolating non fused switch on the load side of the meter. They want to be able to isolate it on both sides. You also have to be very careful on what side is line and load — if you do it backwards it simply won’t count. I’ve done that before.

I agree that it’s unnecessary, and so are half of their other rules like requiring bypasses in all sorts of applications where no one will ever use a bypass to service a meter this day in age.

 

[skizzlez]

@jaggedben @ggunn @BackCountry

I appreciate the discussion here guys -- but the word is back, and they already rejected the update w/ a disconnect on both sides of the meter. Now, maybe it is not rejected based on technical merit, but you'll like this.

---------
Comments from Approvers: Approver 2 Comment: This application has been rejected. Please correct the following before resubmitting:

One-Line:
3.21.1 - Other AC Disconnects shall not be labeled or identified as a “Utility” AC Disconnect, if applicable. With this design only a single AC disconnect should be distinguished as the 'Utility AC Disconnect.' The utility AC disconnect must be properly located according to 3.21.2 or 3.21.3.

Site Plan:
4.7 - Main service entrance, all meter locations, disconnects, transformers, proposed and existing DER systems. Please ensure any changes made to the One-line are made to the Site Plan as well.
-------------

Yes, In my one-line I had them both labeled as "Utility AC Disconnect" - and I can easily make a change here. But once again, this is annoying as there is no possible way to communicate with these folks on 'exactly what they want'! Here is the entire 3.21 section from their interconnection manual:

AC Disconnect
3.21 A visible‐open type, lockable, and readily accessible AC disconnect for purposes of isolating the DER from the utility source labeled “Utility AC Disconnect,” “Photovoltaic Utility AC Disconnect,” or similar shall be shown
3.21.1 Other AC Disconnects shall not be labeled or identified as a “Utility” AC Disconnect, if applicable Note: The “Utility AC Disconnect” must be accessible to Xcel Energy’s personnel 24/7 without escort, hindrance, or delay. Rack‐out/draw‐out breakers5 do not qualify as a “Utility” AC Disconnect.
3.21.2 For installations that require a Production Meter, the Utility AC Disconnect shall be located between the DER and production meter
3.21.3 For installations not requiring a Production Meter, the Utility AC Disconnect shall be located between the DER and main service
3.21.4 When multiple DER units are existing or proposed on a single service: if a single Utility AC Disconnect cannot be used to disconnect all DER, all Utility AC Disconnects should include numerical identification such as “Utility AC Disconnect 1 of 2” or similar. The number of disconnects required to be operated to isolate the DER from the utility should be clear.

OK, so reading this to me sets off a few more things.. Firstly, they want me to change the name so that only one is labelled the Utility Disconnect. Fine. If that is the case, 3.21.2 is applicable and says the "utility ac disconnect" should be the second disconnect in the one-line. What would the first one be called? Auxiliary PV disconnect ? and if so, am I reading that correct? The one on the supply side is not technically BETWEEN the DER and production meter...

Secondly, 3.21.3 seems unrelated here, as I have a production meter
Thirdly, 3.21.4 seems unrelated, as I don't have multiple DER units.

Thoughts?

Image is what I had... I also understand from the conversation that the second disconnect (whatever the heck you wanna name it) doesn't technically need to be fused. But at this point, it doesn't seem to matter.

 

[wwhitney]

Haven't carefully followed the whole thread, but I understand that in the last diagram posted, the top connects to the DER, and the bottom connects to the utility. Then:

From the OP, "3.7 - Main service protection between DER and the utility. There must be protection in the form of a breaker or fused AC disconnect between the DER and utility located immediately after the main service meter, before the production meter." Check 3.7's text, but if correct that requires the middle 200A disconnect in your diagram. 3.7 should tell you what to label it.

From your last post, "3.21.2 For installations that require a Production Meter, the Utility AC Disconnect shall be located between the DER and production meter." So that requires the upper disconnect in your last diagram, and tell you what to call it.

Seems weird that their rules call for two disconnects, but that's how it reads.

Cheers, Wayne

 

[skizzlez]

Haven't carefully followed the whole thread, but I understand that in the last diagram posted, the top connects to the DER, and the bottom connects to the utility. Then:

From the OP, "3.7 - Main service protection between DER and the utility. There must be protection in the form of a breaker or fused AC disconnect between the DER and utility located immediately after the main service meter, before the production meter." Check 3.7's text, but if correct that requires the middle 200A disconnect in your diagram. 3.7 should tell you what to label it.

From your last post, "3.21.2 For installations that require a Production Meter, the Utility AC Disconnect shall be located between the DER and production meter." So that requires the upper disconnect in your last diagram, and tell you what to call it.

Seems weird that their rules call for two disconnects, but that's how it reads.

Cheers, Wayne

Wayne,
Yep, seems that the upper disconnect should be the "utility disconnect" and the lower one (pre production meter) should be the "Main Service Protection Disconnect" -- 3.7 doesn't directly name it. I assume if I name it this "Main Service Protection Disconnect" they will raise issue as, it is really related to the PV system. So maybe "Main Service Protection PV Disconnect" or something along these lines... lol

3.7 entirely by the way:
Main service protection between DER and the utility Note: This protective device shall be provided immediately after the main service meter. Typical protective devices include circuit breakers and fuses. An unfused disconnect is not considered a protective device. When connected behind a main service panel, the main service breaker will suffice as the protective device

Thanks
Jason

 

[jaggedben]

...

3.21.2 For installations that require a Production Meter, the Utility AC Disconnect shall be located between the DER and production meter
...

This is a stupid rule. That said, it seems that this is the one they want labeled 'Utility AC Disconnect'. i.e. delete the 'Utility AC Disconnect' label from the one that is below the Production Meter in your drawing. That one is still required by 3.7 but for some reason they don't want it labeled as their disconnect.

 

[skizzlez]

This is a stupid rule. That said, it seems that this is the one they want labeled 'Utility AC Disconnect'. i.e. delete the 'Utility AC Disconnect' label from the one that is below the Production Meter in your drawing. That one is still required by 3.7 but for some reason they don't want it labeled as their disconnect.

That'll be the next move here. It is just sad that they don't have a phone number, contact email or even office hours to simply resolve these trivial points.

Will report back when they reject again.

=)

 

[jaggedben]

At least you got a reply within two days? PG&E would take at least two weeks with this one.

 

[skizzlez]

At least you got a reply within two days? PG&E would take at least two weeks with this one.

Yeah. I was surprised. Last time was 5 days.. Could be a simple phone call!!!

 

[skizzlez]

all - just got an email saying the application has been deemed complete. It is now moving on to the next stage of engineering evaluation etc.

Thanks for all the conversation, i'll keep you posted on what comes next.

 

[skizzlez]

Long time no talk...

Before I dig in, here is the Xcel process:

So I just passed step 3 -- the completeness review.

This afternoon, I received word that I've now failed the "initial review" - which must be the same as the step 4 engineering review. Or at least part of it. Here are their comments:


The more detailed section points to the red circle below...


Section 3.4.4.1 through 3.4.4.3 can be seen here, just ctrl F 3.4.4.1 and it will show you...
https://www.xcelenergy.com/staticfiles/xe/Regulatory/Regulatory PDFs/rates/MN/Me_Section_10.pdf


OK, so TLDR, it seems that i'm now at a position where Xcel wants to do additional reviews of the grid and my property to evaluate if the size can be installed "safely". The $200 deposit is a placeholder, that gets them started, and then i'll be on the hook for whatever additional fees they want to throw at me -- Plus whatever remedies need to take place to allow me to move forward. The DER Size on Shared Secondary is interesting, i'm not sure what that means -- any thoughts??

Lastly, the section 3.4.5 in that pdf says this:
If the proposed interconnection passes the supplemental screens in sections 3.4.4.1, 3.4.4.2, and 3.4.4.3 above, or if the proposed interconnection fails the screens, but the Area EPS Operator determines that the DER may nevertheless be interconnected consistent with safety, reliability, and power quality standards, the interconnection shall proceed as follows:

it is almost as if they just want someone to approve the size and the lines to the sub station?

FYI - i already paid the $200 deposit, and am going to see what happens next..
Thanks for listening to my saga!

 

[jaggedben]

Your drawing shows a very, very large system for a 200A service so I'm not particularly surprised you're getting kick back at this stage.

This may be out of date but a few years ago I read that PG&E would approve any system interconnection less than 5kW without doing an extensive engineering review. Anything higher got looked at by engineering. So that may be all they are telling you at this stage. Still, our customers often have to wait for transformer upgrades if there's more than about 15kW of systems connected to a shared transformer. Sometimes less. Yours is more. Around here we can interconnect up to 30kW and they can't charge the customer for network upgrades on a shared transformer, just make you wait for it (months if not more than a year). The rules may not be so lenient in your state.

 

[skizzlez]

Your drawing shows a very, very large system for a 200A service so I'm not particularly surprised you're getting kick back at this stage.

This may be out of date but a few years ago I read that PG&E would approve any system interconnection less than 5kW without doing an extensive engineering review. Anything higher got looked at by engineering. So that may be all they are telling you at this stage. Still, our customers often have to wait for transformer upgrades if there's more than about 15kW of systems connected to a shared transformer. Sometimes less. Yours is more. Around here we can interconnect up to 30kW and they can't charge the customer for network upgrades on a shared transformer, just make you wait for it (months if not more than a year). The rules may not be so lenient in your state.

Yep. It is pretty large for a home gamer around here. But the system you apply through. And the xcel solar rewards program basically call out 40kw as the max size where you can follow the fast track process

I’m down for the engineering review. But like you’ve said, it’s a large system for a 200a service. But. I have two 200a services on the property. So it’s not that crazy. Their system doesn’t really give you the ability to explain that.

Hoping the engineering review they will actually reach out??

I just don’t fully understand how I could theoretically utilize 400a of service to my property. But can’t generate 120a. lol.

 

[jaggedben]

The utility is not obligated to install infrastructure on their side to constantly supply 200A and they typically don't, especially for residential. They will size a transformer to what they think will actually be drawn, and they won't mind if it gets overdrawn a few hours per year. The max output of a solar system that offsets x amount of energy per year is typically 5-7 times the annual average power of that amount of energy, and a large percentage of that energy output happens continuously in the summer for many hours straight. I other words you are installing a 26kW system for someone who possibly never uses much more than 4kW, but uses that steadily and consistently. Or more likely the reality is somewhere in between, but the point is that the transformer could very well be taxed by the backfeed in summer in a way it is never taxed by the load. This, among other things, is what they'll be looking at in their review.

 

[skizzlez]

The utility is not obligated to install infrastructure on their side to constantly supply 200A and they typically don't, especially for residential. They will size a transformer to what they think will actually be drawn, and they won't mind if it gets overdrawn a few hours per year. The max output of a solar system that offsets x amount of energy per year is typically 5-7 times the annual average power of that amount of energy, and a large percentage of that energy output happens continuously in the summer for many hours straight. I other words you are installing a 26kW system for someone who possibly never uses much more than 4kW, but uses that steadily and consistently. Or more likely the reality is somewhere in between, but the point is that the transformer could very well be taxed by the backfeed in summer in a way it is never taxed by the load. This, among other things, is what they'll be looking at in their review.

Once again, killing it with the response detail!

Yeah, this property does indeed use the power! annual average is higher than this system is capable, but the system is designed to maximize the available roof space on the detached building -- without adding any to the residence.

If we wanted to maximize the system based on utilization, we would need to be at 38kw. -- and add another 25 panels.. lol