Hendrix
Senior Member
- Location
- New England
How do inspectors deal with these? Where and how would you deal with the AC power coming streight off the aray?
micro inverters
- Thread starter Hendrix
- Start date
- Status
- Location
- Simi Valley, CA
I say "nice install, I don't know why more companies aren't using these" and I sign the card and get in my truck and go to the next job.
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
One thing I hope most inspectors would understand is that article 690 explicitly allows a connector (such as the one Enphase uses between its M215 and the trunk cable) to serve as an AC disconnect if it is listed for the purpose. Also, that the various requirements for DC PV source and output circuits should not apply to inverter output circuits for micro-inverters, even though the conduit coming from the roof may look the same. (Yes, you can run romex from micro-inverters, where it is appropriate to run romex, as long as you have the proper size DC GEC.)
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
- Location
- Simi Valley, CA
Can I come install in your jurisdiction?
Sure, I average about three solar inspections a day, I think I have it figured out.
- Location
- Simi Valley, CA
You can use the breaker as the AC disconnect too. The seperate, lockable one is mostly required by the POCO's and the fire departments, that don't understand solar.
micro inverters
I did an inspection on a similar installation yesterday but did not pass it, because there was no dc connection to building ges. Also the egc could not qualify as a gec/egc because it was not of sufficient size and it was not continuous.
Do you agree with what I did? Comments always welcome.
I did an inspection on a similar installation yesterday but did not pass it, because there was no dc connection to building ges. Also the egc could not qualify as a gec/egc because it was not of sufficient size and it was not continuous.
Do you agree with what I did? Comments always welcome.
kbsparky
Senior Member
- Location
- Delmarva, USA
Would you allow a connection from the SMA box to an intersystem bonding strip?
david
Senior Member
- Location
- Pennsylvania
I looked at one of these installations today using micro invertors. 240 volt AC had some concerns.
The conduit from the array has 5 sets of 10 AWG ungrounded, 5 -10 AWG N & Two 6 AWG grounds to a main lug distribution panel in the basement.
The panel is being used as a combiner for the array circuits. Five two pole 20 amp breakers back feed the distribution panel.
Two # 6 AWG Un-grounded conductors and One #10 AWG neutral and one # 6 ground back feed a 70 amp Two pole breaker in a 150 amp sub panel in the basement
The 6 AWG -10 AWG N- 6 AWG Grounds feed the utility required disconnect on the out- side of the single family dwelling from that disconnect they back feed ( 70 amp 2/pole breaker)the 150 amp sub- panel in the basement.
I asked some questions on this installation the contractor said no inspector ever questioned him on this in the past and he installed a hundred or so just like this. I?ll will give him the benefit of his specialized experience in this field; I will go back over article 690 and address my concerns
The conduit from the array has 5 sets of 10 AWG ungrounded, 5 -10 AWG N & Two 6 AWG grounds to a main lug distribution panel in the basement.
The panel is being used as a combiner for the array circuits. Five two pole 20 amp breakers back feed the distribution panel.
Two # 6 AWG Un-grounded conductors and One #10 AWG neutral and one # 6 ground back feed a 70 amp Two pole breaker in a 150 amp sub panel in the basement
The 6 AWG -10 AWG N- 6 AWG Grounds feed the utility required disconnect on the out- side of the single family dwelling from that disconnect they back feed ( 70 amp 2/pole breaker)the 150 amp sub- panel in the basement.
I asked some questions on this installation the contractor said no inspector ever questioned him on this in the past and he installed a hundred or so just like this. I?ll will give him the benefit of his specialized experience in this field; I will go back over article 690 and address my concerns
- Location
- Simi Valley, CA
I don't believe that the micro inverters give you any exception for the 120% rule.
elohr46
Senior Member
- Location
- square one
Not sure if I am understanding your question correctly but I don't think the 120% rule applies if your panelboard is being used as a combiner box that contains only backfed breakers and is line side connected to the incoming service. I would post this question in the PV forum.
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
The point about the connector disconnects (AC and DC actually) is they satisfy the requirements of 690.15 (D), for inverters mounted in not-readily accessible locations.
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
Probably I agree with you. Enphase microinverters have a lug on the inverter housing for the connection of the DC GEC. If they did not connect a suitably sized GEC to those lugs, then they fail 690.47. Almost always with micros the grounding method used is going to be 690.47(C)(3). I take it that irreversibly spliced is substitutable for 'continuous.'
Note that when manufacturers start integrating the micros into the solar panel junction boxes, with no exposed DC wiring, they will be 'AC modules' and these requirements will no longer apply. An EGC will then be sufficient.
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
The 120% rule applies to all panels here (except see below), although there is some ambiguity as to whether you must apply 100amps or 70amps to the 150amp sub. Without more details, we can't be sure, but it sounds like this system may be in serious violation.
The solar combiner should be a 150 amp panel to be fed by (5x20)+70amps ) And the breaker feeding the 150A sub on the utility side must be 100A or less to be backfed by 70A of solar. (And the 70A breaker must be installed at the opposite end of the busbars from the utility feed.) And whatever the main panel is, it must also meet the 120% rule.
Frankly, it sounds like maybe you shouldn't.
It's somewhat a matter of interpretation, although the code writers pretty clearly did not intend to allow 'AC combiners' to be excepted from the 120% rule. My opinion is that inspectors should give leeway if they feel sufficiently assured that the combiner will never get reconfigured to handle any loads.
For more on this, see:
http://forums.mikeholt.com/showthread.php?t=141357
http://forums.mikeholt.com/showthread.php?t=140547
http://www.iaei.org/magazine/2011/0...-utility-interactive-pv-inverter-connections/
http://solarprofessional.com/forums/forum/messageview.cfm?catid=3&threadid=749&enterthread=y
elohr46
Senior Member
- Location
- square one
I completely agree that the wording of the code does not allow for an exception to the 120% rule for panels used as an combiner box. I happen to know of a small number of these configurations with proper signage approved by the local AHJ, I hope there is some relief by the CMP in the near future for it does look like a lot of overkill by the NEC.
thanks for posting those articles, they were very informative.
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