PV system labeling - verification or correction appreciated.

[Gaff]

Figuring out the correct labeling for my PV System has been the most confusing part of the entire process! I searched this site and quite a few others as well as my book on PV design and installation. I think I have it figured out but would like to make sure - and if have something wrong I would appreciate any correct information.

I'll start with a brief description of my system.

Two panel arrays: one with eight 280W panels the other has twelve 280W panels. Enpahse M250 micro-inverters are used on every panel.

The two arrays are combined in combiner box / subpanel in the attic. This combiner box has two 15A double pole breakers - one for each array.

The home run from the combiner box / subpanel travels through the attic (not in conduit - inspector said this was ok) and then when it exits the attic down the side of the house it is in schedule 40 PVC.

The PVC runs to the AC disconnect mounted above the utility meter then into house and into main load center.

So here is what I am planning to do to meet the labeling requirements.

1) On the combiner box / subpanel place a sticker that reads "WARNING: TURN OFF PHOTOVOLTAIC AC DISCONNECT PRIOR TO WORKING INSIDE PANEL.

2) For the wiring through the attic and inside the PVC place stickers every 10' that read: WARNING: PHOTOVOLTAIC POWER SOURCE.

3) For the AC Disconnect place a sticker that reads: MAIN PHOTOVOLTAIC SYSTEM AC DISCONNECT.

4) On the utility meter place a sticker that reads: WARNING – DUAL POWER SOURCE SECOND SYSTEM IS PV SYSTEM.

5) At the 30A two pole breaker in the main load panel place a sticker that reads: PHOTOVOLTAIC AC DISCONNECT – MAXIMUM AC OPERATING CURRENT: - NOMINAL OPERATING AC VOLTAGE:

6) Place a plaque/label in the main load center identifying the location of the AC Disconnect.

I also have sticker where I can list the following: Nominal operating AC voltage; Nominal operating AC frequency; Maximum AC power; Maximum AC current; Max overcurrent device rating for AC module protection. Possibly this should also be in the combiner box / subpanel?

Any input or advice is very welcome.

[sensij]

I'm not sure about the labeling... if you ask, your AHJ may be able to tell you if what you are suggesting complies. Off the cuff, 15 M250's would need a 20 A breaker (15 * 1.0 * 1.25 = 18.75 A).

[f1b]

Off the cuff, 15 M250's would need a 20 A breaker

He has 20 M250s.
20 * 1 * 1.25 = 25A; so the 30A breaker should be OK (assuming wire sized appropriately)

[f1b]

RE: Labels - my advice is to see if there's any similar installs in your area and use them for reference.

I'd think the size info would be appropriate at the AC disconnect... Or possibly the combiner/subpanel. (Since that label is only $1.50, I'd probably put it at both)

[Gaff]

My wiring and breakers are all set thank you - just looking for experienced feedback on the labeling requirements.

Does anybody else with pv system labeling experience have any input? If so I would appreciate it. I am planning to schedule the inspection next week so if I need additional or different labels I would like to order them asap.

Thanks for your time.

[sensij]

My PV system labeling experience says that different AHJ's look for different things, which is why I suggested you talk to them directly. you might want to indicate what code cycle you are on, requirements have changed over time.

[deyounte]

He has 20 M250s.
20 * 1 * 1.25 = 25A; so the 30A breaker should be OK (assuming wire sized appropriately)

I recommend you check the Enphase documentation on the M250 installations. Please search "enphase breaker m250". You will find that Enphase documentation limits any one circuit of M250's to a total of 16 units. The result is that with 20 units, you will have at least 2 circuits. It doesn't matter how you split that up as long as they are all less than or equal to 16 units. With the max 16 units on a circuit they are talking about 20A breaker. Sorry if this was unexpected.

BTW, This is USA 240V single phase specific to the M250. I'm not sure about 3-phase or other voltage levels they may support for their other models and other regions. Depending on your situation you would have to look that up.

Tim D.
Melbourne, FL

[sensij]

OP's design is fine. My earlier post was.a mistake, thinking there would be 15 panels going into a 15 a breaker. There are only 12 panels on the longest string. Once the two strings are combined, the 30 A is ok for the protection at the MSP. Same as if the circuits had gone to a subpanel, instead of a combiner.

[solarix]

Without knowing your AHJ and without going into a deep dive into the underlying code, here are my comments:

1) On the combiner box / subpanel place a sticker that reads "WARNING: TURN OFF PHOTOVOLTAIC AC DISCONNECT PRIOR TO WORKING INSIDE PANEL.
Combiner label needs to warn against adding any loads to the combiner subpanel. Usually we intentionally use a panel that has just enough space for the solar breakers.

2) For the wiring through the attic and inside the PVC place stickers every 10' that read: WARNING: PHOTOVOLTAIC POWER SOURCE.
"inside the PVC"? my AHJ does not allow pvc conduit for solar. Yours may especially on the AC side.

3) For the AC Disconnect place a sticker that reads: MAIN PHOTOVOLTAIC SYSTEM AC DISCONNECT.
Also needs a label "Warning - electric shock hazard, both line and load terminals may be energized in off position"
(a totally bogus misunderstanding of how grid tie solar works by the code authorities, but required nevertheless)

4) On the utility meter place a sticker that reads: WARNING – DUAL POWER SOURCE SECOND SYSTEM IS PV SYSTEM.
Label on solar meter (if meter is required): PHOTOVOLTAIC POWER SYSTEM DEDICATED KWH METER".
Label on Main Service: "CAUTION: MULTIPLE POWER SOURCES"

5) At the 30A two pole breaker in the main load panel place a sticker that reads: PHOTOVOLTAIC AC DISCONNECT – MAXIMUM AC OPERATING CURRENT: - NOMINAL OPERATING AC VOLTAGE: Also needs a 2nd label: "BACKFED SOLAR INTERCONNECT, DO NOT RELOCATE BREAKER"

6) Place a plaque/label in the main load center identifying the location of the AC Disconnect.

[Gaff]

Thank you for taking the time to respond Solarix - I really appreciate it. I will follow your suggestions.

I verified a couple of weeks ago with the electrical inspector that schedule 40 PVC conduit on the exterior of the house would be okay as long as I used an expansion/contraction fitting.