Newbie here doing a 20.8kW DYI install (80 sunMAX 260W panels with microinverters)

[pclausen]

Very nice job on the ground wires!

They look awfully similar to what I just got in today.



The ones I'm currently using are not rain-tight at all, even though the guy at the counter at tri-state electric was trying to convince me they were, as long as I made them real tight. I called them ahead of time and they assured me what they had was rain-tight. Drove 45 mins. Was pretty pissed when he showed me what he had. A couple of other electricians at the counter said those were also what they always used outdoors. They were cheap, so I picked them up. Anyway, that is why I have been procrastinating puling the #10 wires.

Thanks for the link to the real deal!

Thanks for the Mike Holt video. Never actually seem him live before.

And yes, my building dept. has been great to work with as well. There as some things however, like my particular shop building, the he would have to come out and see in person to make a call on the GEC "stunt" I'm trying to pull.

I'm going to a meeting at the local community center later this week. It is hosted by the POCO and will feature heavy appetizers and drinks. The meeting was requested by several members who have photo-voltaic generation at home and thought that an ongoing conversation with their cooperative and with other renewable generation members would be helpful.

President and CEO will lead the discussion, providing an overview of where the POCO is with their solar distribution project and with the community solar garden project as well as a quick summary of the specifics of the Net Energy Metering Rider, which is based upon language provided by the State Corporation Commission. Should be very interesting and I applaud them for reaching out to their members like that.

[tyab]

I live in a rural area also and I have found our building department to be very helpful. When I have a question - I give them a call and so far I have gotten clear answers. I would give them a call and ask about the structural metal and use of a GEC and in particular with 690.47(D) and ask them if they will accept what you are doing or if they want a separate #6 run. 690.47(D) is a mess in any case, here is a good video on 690.47 and goes into the issues with (D). Note that 690.47 was reworked in the 2017 NEC, (D) was renumbered to (B) and is now optional.

https://www.youtube.com/watch?v=Ypo99VRxT44

Here is what insulated throat EMT connectors 3/4" look like (these are yellow). According to code they are NOT required unless you are using #4 or larger wire but not a bad idea given they are only slightly more expensive than the not insulated EMT connectors and give a margin of safety against damaged wire when pulling.

[pclausen]

The 2014 code also requires a GEC ground and it is covered in 690.47(D). Review that section carefully and it requires that 250.52 be followed for that ground - and there is an exception allowing structural steel but you will need to read that carefully. Be aware if you see the term "continuous" there are very special requirements for that.

I read 250.52 and I don't meet that to the letter regarding the continuous reference. That said, I'd say there's a 50/50 chance the AHJ will be ok with the way I did it. Like I said, running individual #6 from each of the 3 arrays to the ground rod is not that big a deal. Technically, the entire shop is a subpanel location from the main house and this only has a single ground rod (I do have 2 at the main house). Not sure if that plays into it. We'll see what they say.

[pclausen]

Are you planning to use the 120% rule?
Because it looks like you've got a number of strings, and will have multiple breakers.
And my understanding of the 120% rule is you only get 1 breaker at the opposite end, not 3 or 4.
But I can't see how it'd be a safety issue, so if your AHJ is OK with it I think go for it.

Yes I plan to use the 120% rule. The 200A main breaker is being replaced with a 150A one. So 200 * 1.2 = 240A - 150A = 90A. With 4 20A breakers, I'll have 10A to spare. My AHJ said that as long as I had space for the PV breakers in the main panel, he was ok. He didn't even mention the 120% rule. Keep in mind that I live in a rural county in Virginia and the entire AHJ department consist of 3 people. My permit number is 311-2016 and was pulled in August, so they have maybe 400-500 total permits for 2016 and there might be a few others related to solar panel installs.

[foo1bar]

I kind of have my own question but i donot know where to post it?

You can click on the "Solar Panels for your Home, Grid Tied Solar PV"
and then "+ New Topic" to add a new thread under grid-tied section.
If grid tied isn't the right section, find the right section and add a new thread under there.

[foo1bar]

Here's where it drops into the panel.

Are you planning to use the 120% rule?
Because it looks like you've got a number of strings, and will have multiple breakers.
And my understanding of the 120% rule is you only get 1 breaker at the opposite end, not 3 or 4.
But I can't see how it'd be a safety issue, so if your AHJ is OK with it I think go for it. If they do have want everything combined before going to the backfeed, then it should be easy enough to add a panel next to your existing one. And combine everything in that new subpanel.

[pclausen]

So the EGC green wires from the microinverter strings will land on the ground bar in the plastic junction box like so:



And a single green ground wire will run in the conduit to the ground bar in the breaker panel.

The GEC from each physical array is what is tying into the metal structure.

When I built the metal building 15 years ago, the LHA has me tie all the metal members together with #4. So I made the assumption that he would be ok with me using any metal of the building as a GEC conduit. I guess we'll see how picky he is. If me makes me run #6 from each of the 3 physical arrays to the ground rod, so be it. It will take about 200' to do so. I'm hoping to avoid that, but it is really not that big a deal if he makes me.

Given that #4 is used to tie some of the structural members together, it might be that they are not considered continuous and I have to do the 3 individual 75' runs to the ground rod. I'll check out 690.47(D).

[Mike90250]

I know, metal frame, metal roof, metal everything. I still don't like inviting lightning strikes indoors to ground.
And did you polish paint off between beams, or relying on the bolts to connect the metal ?

[tyab]

EMT into a plastic box just requires the lockring - the bushing is what you use if you have wires coming out of EMT in free air. Hopefully your EMT has an insulated throat so there is no risk of scraping the wires.

I have lots of pictures of insulated throat EMT connectors here (most are yellow and a large one is green)


You are going to need two grounds and they are not the same - they are considered separate. The EGC ground (green) wire from your microinverters and it can tie to any structural metal along the way (and should) if that metal is used as part of the EGC (for example, EMT conduit that is strapped to a metal support or metallic junction boxes). The 2014 code also requires a GEC ground and it is covered in 690.47(D). Review that section carefully and it requires that 250.52 be followed for that ground - and there is an exception allowing structural steel but you will need to read that carefully. Be aware if you see the term "continuous" there are very special requirements for that.

Looks good so far, I'm busy myself getting rails up.

Admin note I removed the link, please dont link to that site, cheers.

[MULINS22]

I kind of have my own question but i donot know where to post it?

[pclausen]

I got the junction box drilled. Only issue is that the plastic sidewall is too thick to allow both the lock nut AND bushing to fit on at the same time. So I can either do this:



Or this:



Problem with using just the bushings is that I can pull out the connectors without much force. Problem with using just the lock nut is that you are supposed to also use a bushing, Perhaps I can glue the bushings on?

Also worked on the grounding for the arrays. There are 3 physically separate arrays (due to metal expansion). All 3 are being grounded to the main metal building ridge plates. I grinded the paint off in the areas I would be making contact.



And here are 2 #6s going to one side of the roof. The 3rd array will be grounded in a similar fashion at the opposite end of the roof.



The temptation was too great to not go ahead and connect the panels temporarily (running 12-4 cable I had laying around from each string down into the breakers. Still have a few panels not working yet, but I was making just under 10kW around noon.



My meter transmit usage back to the POCO on a daily basis. I confirmed that it has been running backwards for the last few days. No usage at all. Hehe.



Once I'm official and get the current meter replaced with a net meter, I suspect I'll be able to see consumption vs. whatever I push into the grid.

So far I have pushed 180kWh back into the grid (less whatever I used).

[pclausen]

Hopefully the 5ft rule is related to DC only.

I cheated on the 1-1/4" EMT bending and used 3 90s and a 45 at the ceiling ridge. So all I had to do was make 4 straight cuts.

[tyab]

I seem to recall a code section that only allows 5 ft of energized conductors inside of a structure from a PV system before a disconnect but for the life of me I can't find it (it might have been DC only - or it may have been 2011). There is a 5ft requirement as part of rapid shutdown but microinverters by design easily meet rapid shutdown so that is not it. I'll look at 690 and 705 later tonight when I have more time.

Bending 1-1/4" EMT is some serious bend power - you did an amazing job. I'm really jealous of your shop.

[pclausen]

Thanks. While I was at Lowes picking up my 1-1/4" EMT, I went ahead and picked up a couple of extra 100' spools of each color, just in case I run out. If I don't, I'll just return it unopened.

Got the 1-1/4" EMT all installed. It is right at 40' total distance from the hole in the roof, to the breaker panel.

Here are some pic. This first one shows the entire run.



Here's where it drops into the panel.



And the turn up onto the ceiling.



And where it penetrates to the roof. Had to use a pallet as a working platform.



And finally the view from above. This pic was taken before the conduit was installed inside. It is now perfectly parallel with the roof-line. As you can see, everything will be hidden below a solar panel, so things should stay nice and dry.

[tyab]

THWN means that it has its own wet rating (typically 60C) and it is lower than dry rating . THWN-2 means that both wet and dry have same temperature rating (typically 90C). From the sticker THWN will be ok since we are using 60C for the conduit.

#10 black 100 ft spool is about $25 at both Lowes and HD.

It is ok to mix THWN and THWN-2 for your circuit - the key is just to not exceed your design temperature which is 60C for you which #10 won't. If you are bored, 310.10 talks about some of this stuff - I had to review 310.10(H) for my parallel run and this is where you can't mix insulation types.