Progress Energy question for 22K, residential Tier 2 installation

[innersurffer]

We have a residential customer we are in the process of trying to put a quote together on. This residential customer has a 200A main and wants to inject 22K, (aporximatly 92A, 100 amps of injection) into his service. The potential customer is wanting string inverters. If we used (4) SB5000TL?s and added another sub panel (splitting the load between two panels to comply with 690.64(B)(2)) would this be correct? Also, considering Progress Energies polices, would they have a problem injecting this size system into a 200 amp drop? I know there is a 80% rule for commercial tier 2 but I?m not sure about residential tier 2. Your thoughts and opinions are greatly valued.:?

 

[ggunn]

We have a residential customer we are in the process of trying to put a quote together on. This residential customer has a 200A main and wants to inject 22K, (aporximatly 92A, 100 amps of injection) into his service. The potential customer is wanting string inverters. If we used (4) SB5000TL?s and added another sub panel (splitting the load between two panels to comply with 690.64(B)(2)) would this be correct? Also, considering Progress Energies polices, would they have a problem injecting this size system into a 200 amp drop? I know there is a 80% rule for commercial tier 2 but I?m not sure about residential tier 2. Your thoughts and opinions are greatly valued.:?

At 240V, 22 kW would take OCPD of 125A (or 4 X 30A = 120A with those inverters). That's obviously way too much for a backfed breaker in the 200A main (no matter how you break it up into subpanels the total inverter OCPD counts toward the 120% rule in the main panel); a supply side tap could work but whether it is allowable is a question for your AHJ. Can you get an appointment with the AHJ's inspector and present him with your question?

 

[innersurffer]

Since AHJ aren't always as savvy with Photovoltaic rules we may just do what you said and draw him a picture.
Hoping he (Duke/Progress Energy) may be a form member and answer this question more directly.
Thanks for the input,

 

[cadpoint]

If you go to Progress and read through their web page theres a note that the pages are in Flux.

I went over to Duke's Page and found this.

https://www.progress-energy.com/florida/business/builders-contractors/index.page?

The combined service now has a up to date PDF downloadable that I saw a copy of at city counter. This states a lot of various single line drawings of "how too" for contractors installations. It included PV!

This PDF is really tough to find, you might call Progress/Duke and look in Building Resources, or some of the other various line items, if you don't find it.

This is a link one step inside Building resources.
https://www.progress-energy.com/florida/business/save-energy-money/builder-resources.page?

The Standard installs are heavier to Duke's style than to Progress. FFTW.

 

[ggunn]

Since AHJ aren't always as savvy with Photovoltaic rules we may just do what you said and draw him a picture.
Hoping he (Duke/Progress Energy) may be a form member and answer this question more directly.
Thanks for the input,

You did get my point that no matter how you break up the inverter feeds in subpanels, all the inverter OCPD ratings contribute to the 120% rule if you bring them into the main panel no matter how they are connected, right? With 120A or 125A total OCPD ratings for the inverters and a 200A main panel, your only option to interconnect is a supply side tap.

 

[Zee]

I'd like to step back for a second from how you framed the Q: "how to install 22 KW (!) in a 200 A panel?

If the customer needs 22 KW of PV....isn't the 200A service already too small for their needs?

Why not just get a new 400Amp service, especially on such a huge residential job?

EVEN SO.....there is no way to meet the 120% rule with load side breakers - unless the PV is supply side connected.

(most you could do would be 4 @ 3800 W inverters = 4 @ 20A PV breakers = 80A = max allowable exactly)
(or 2 @ 8000 W SMA inverters (if current limited to 32 A each) = 2 @ 40 A PV breakers = 80 A)


BTW - 92 A is incorrect. As GGUNN pointed out: you need 125% of the rated, inverter amps.

 

[innersurffer]

I understand about 640.42b2 and woild not sub the feed but would use tap rules on the load side of the meter. There should be no need for a 400 amp service upgrade because I am going to tap after the meter and make each new panel feed (3) 30 amp discos. That will be an existing 200 amp panel with a SB5000TL (OCPD 30 amp) and (3) new 30 amp discos (fused) feedings the remaining SB5000TLs. The SB5000TLs have a mac output of 22 amps and require 30 amp Max protection according to SMA. THOUGHTS?

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[innersurffer]

The system is not 22Kw I it's 20KW.

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[jaggedben]

I understand about 640.42b2 and woild not sub the feed but would use tap rules on the load side of the meter.

Sounds like a supply side connection to me, as these guys have been telling you. Since the meter is not the service disconnecting means, you are talking about installing a new set of service entrance conductors under article 230. (To be clear, the "tap rules" in 240.21(B) would not apply unless you're tapping on the load side of the existing main breaker.)

There should be no need for a 400 amp service upgrade because I am going to tap after the meter and make each new panel feed (3) 30 amp discos. That will be an existing 200 amp panel with a SB5000TL (OCPD 30 amp) and (3) new 30 amp discos (fused) feedings the remaining SB5000TLs. The SB5000TLs have a mac output of 22 amps and require 30 amp Max protection according to SMA. THOUGHTS?

If you're tapping new service entrance conductors, I don't understand why you wouldn't just tap all four inverters off of those conductors. Or install a new 200A solar sub for all the inverters. Putting one of them in the existing panel may not be a code violation but it strikes me as bad practice not to group all the solar disconnecting means together.

 

[Zee]

This is in fact a supply side connection.

"After the meter" is vague, "after" from which direction?

You mention, "Each panel feeds 3 - 30A discos". What panels? You hadn't specified how and where.

"Each panel" implies several panels. How many?

30 A rated disco not OK for supply side. You need - per code - Minimum 60A for any supply side connection!

You are installing a NEW SERVICE. ====> Supply side tie = new service = connecting between meter and main OCPD.
That involves a whole new set of codes and local utility regs, the exact same as installing a new service for a home.

30A OCPD is correct for SMA SB5000TL.

Given the importance of your issue, and the fact that you are asking for help, i am not finding it clearly explained, or well written.:?

You are on the right track - but the terse explanations from your smart phone aren't helping us too much!

To answer the Q from your first post: Code allows up to the rating of the service to be tied in as solar - if supply side connected. As for your utility i do not know, only they can tell you.

 

[jaggedben]

You are installing a NEW SERVICE. ====> Supply side tie = new service = connecting between meter and main OCPD.
That involves a whole new set of codes and local utility regs, the exact same as installing a new service for a home.
...

Well, no. A new service is different from a new set of service conductors or service entrance conductors. A new service, for example, would have its own new meter. But the point does stand that it's the same rules as for a new service, namely Article 230.

 

[innersurffer]

Thanks

Thanks

Thanks everyone for the insights and advice. Sorry about the brevity with the smartphone. I could not just add another 200A service using tap rules because this would still not comply with the 120% rule of 640.42b2. I will energize (3) of the SB5000TL's using tap rules with (3) 60A discos, fused with 30A (10K AIC Rated) fuses. I will also utilize the existing panel (200A) to feed the one remaining SB5000TL with a 2P, 30A breaker (furthest from the main). This will meet all codes as far as the NEC and be the best value. I guess since I've had no direct Duke Energy responses, I should get the AHJ out to confirm the scenario, or do this during the submission process. Thanks again everyone.

 

[ggunn]

Thanks everyone for the insights and advice. Sorry about the brevity with the smartphone. I could not just add another 200A service using tap rules because this would still not comply with the 120% rule of 640.42b2. I will energize (3) of the SB5000TL's using tap rules with (3) 60A discos, fused with 30A (10K AIC Rated) fuses. I will also utilize the existing panel (200A) to feed the one remaining SB5000TL with a 2P, 30A breaker (furthest from the main). This will meet all codes as far as the NEC and be the best value. I guess since I've had no direct Duke Energy responses, I should get the AHJ out to confirm the scenario, or do this during the submission process. Thanks again everyone.

FWIW, I just went through this with my AHJ and they tell me that a supply side tap for a PV system is not technically a tap and therefore is not governed by the <10', >10' and < 25', and >25' tap rules.

 

[GoldDigger]

But since there is no overcurrent protection, you need to consider the wires as extensions of the service conductors and treat them accordingly (such as not running inside the building, etc.)

Tapatalk...

 

[Zee]

I could not just add another 200A service using tap rules because this would still not comply with the 120% rule of 640.42b2.

You are very welcome. Hope we helped.

I am still a bit confused. What 120% rule are you referring to? I find nothing under 640.42b2. Nor under 690. 42b2, in case you misspelled it.
I assume it is THE 120% solar rule we all know and love :weeping:. 2011 NEC 690.64
If so..... that only applies to load side connections.
That does not apply to your 3 discos. I am trying to understand - maybe i can learn something new.

I am wondering if anyone sees any reason you couldn't install a single new panel (Main lug only) with 4 @ 2p30A breakers, all 4 as main service disco.s.

The 2p30 A breaker in the 200A main is fine.

 

[GoldDigger]

You are very welcome. Hope we helped.

I am still a bit confused. What 120% rule are you referring to? I find nothing under 640.42b2. Nor under 690. 42b2, in case you misspelled it.
I assume it is THE 120% solar rule we all know and love :weeping:. 2011 NEC 690.64
If so..... that only applies to load side connections.
That does not apply to your 3 discos. I am trying to understand - maybe i can learn something new.

I am wondering if anyone sees any reason you couldn't install a single new panel (Main lug only) with 4 @ 2p30A breakers, all 4 as main service disco.s.

The 2p30 A breaker in the 200A main is fine.

Even if the OP installed a panel with a 200A main instead of an MLO panel for the exclusive use of the solar backfeed, some jurisdictions will still not apply the 120% rule to that panel because it does not serve any loads.

 

[jaggedben]

I am wondering if anyone sees any reason you couldn't install a single new panel (Main lug only) with 4 @ 2p30A breakers, all 4 as main service disco.s.

I think that's a great idea.

 

[innersurffer]

The 120 percent rule is not necessarily for how much the panel is under load bit is based on the buss max ampacity. The code does not delineate between a panel full of breakers or empty in 690.64(B)(2) with the "buss" not over loaded by more than 20 percent larger than the max buss size.

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[Zee]

I think that's a great idea.

Well, hey whaddya know, one great idea before thanksgiving. Just in time! I really needed one.....
Y'all have a great holiday.

Surfer,
having beat the 120% issue to death on this forum with the others, I believe GoldDigger meant what he said: many jurisdictions may not apply the 120% rule - specifically to a dedicated solar ac combining panel. An excellent point that can save some serious labor, panel size and cost.
I believe we are all in agreement that the rule applies - none the less - to any panel board, per literal reading of the CODE.

 

[Zee]

InnerS.,
Also, do you realize what the point of the 4 main breakers is, w/o a single main breaker?
The 120% rule will not apply here to the Buss - under any interpretation of the code, unless you have a buss fed from both ends ( e.g main breaker and pv breaker(s) ) . With 4 pv breakers all as main breakers there is no current that needs to be added going both ways, ie. no 120% rule to apply.