PV wire between tilted rows

newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
How do you handle the wiring between tilted rows when there's a few feet to span?

I've done:

1. Put a j-box under one row, enter the j-box through waterproof fittings, just pass the PV wire through the j-box into EMT, run the EMT to the next row into another j-box, exit through another waterproof fitting.

(This is obviously a big pain, especially if you have a bunch of small rows.)

2. Run the wire along a extra little stretch of rail.

3. Just run the wire through free air - secured on each row.

(This is obviously the easiest. The wire is rated for exposure and it is off the roof, but it's definitely better off not directly exposed to the weather and someone else on the roof could damage the wire more easily. But, seriously, it can add a whole person-day to an install to do those conduit runs for PV wire.)

Comments

  • GreenPowerManiacGreenPowerManiac Solar Expert Posts: 453 ✭✭✭
    Re: PV wire between tilted rows

    Panduit Corp. has a "Raceway" system that channels data cables from one point to another. Most commonly found on internet networks between PCs. There may be other brands and sizes. Having worked for them for almost 14 years has its advantages, although I was reluctant not to obtain any in their periodic giveaways.

    It's a small square plastic enclosure to cover the wires from dust, debris and abrasion.
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  • solarixsolarix Solar Expert Posts: 713 ✭✭
    Re: PV wire between tilted rows

    Around here, the inspectors like to see just metal emt run between panels. Not joined to the connectors, just covering the exposed areas with the USE wire running out the EMT ends through bushings to the module cable. Strap the EMT to your frame or whatever. No boxes. We used metal flex conduit for awhile for this, but now they say its not rated for use on roof even though the wire is. Be careful of the temp ratings on your roof wire - generally have to derate its ampacity quite a lot. Putting it in conduit doesn't help the ratings going by the code - but I don't trust even the USE wire in the smokin sunshine we have here.

    Happy Re-new-able Year!
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: PV wire between tilted rows

    The only thing I'd really be concerned about is protection from someone walking between the rows. If you ,keep the conductors separated and off of the roof they should be fine in the weather. If they weren't, we'd be in a lot of trouble with all the utility wires running around in free air.
  • GreenPowerManiacGreenPowerManiac Solar Expert Posts: 453 ✭✭✭
    Re: PV wire between tilted rows

    I guess you're looking for neatness rather than convenience. If you're concerned about what's on a rooftop then consider how often you'll be up there and can you live with wires being seen.

    On the ground there are a few choices. Bury them at least 16" or code depth in your area for frost line or suspend them like the telephone pole wires and make it look strange. Just make it easy to mow around so you're not getting tangled up in a hazardous predicament.
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  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: PV wire between tilted rows

    Not really neatness because the tilted arrays are generally mounted on flat roofs so they can't be seen from the ground. It's the balance between protecting the wires from a possible hazard (people servicing something on the roof) vs. the extra cost/work.

    It's easy to say, do the work, but there's always some limit.
  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: PV wire between tilted rows

    Personally, I'd go with EMT - but if the spans aren't too far, and it's just for protection you might be able to use a nice fat PVC of a ridiculously large size like 1.5", which will not only let you ignore derating factors, but also provide some airflow around the wire while still giving a decent amount of protection to the wire.
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: PV wire between tilted rows

    Span is like 4'.

    dwh, how do you enter and leave the EMT? I did one job where I did it in a jbox everytime, which was a lot of work, and another where I put a connecter, a threaded coupling, and then a plastic connector on the end of the condiut, which was a bit less work.
  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: PV wire between tilted rows
    newenergy wrote: »
    Span is like 4'.

    dwh, how do you enter and leave the EMT? I did one job where I did it in a jbox everytime, which was a lot of work, and another where I put a connecter, a threaded coupling, and then a plastic connector on the end of the condiut, which was a bit less work.

    Ah, well I took the original question as hypothetical - so the answer is, "It Depends."

    As I said, by default personal preference I'd use EMT (#1 in your OP). The PVC idea was just for if the wire was rated for open air outdoor use (as you described in your OP) and you were just looking for some way to keep people from tripping over it or stepping on it.

    Having said that, if I just ran the wire through a large diameter PVC, I probably wouldn't bother with fittings at all. Just tuck the ends of the pipe up under something so there are no loops of wire to get hung up on, and slide the wire through it.

    "Good enough for government work."


    (Of course, you might want to also chamfer the inner edge of the ends of the pipe so it wouldn't tend to abrade the wire's insulation. You would probably also want to strap the pipe somehow to keep it from moving.)
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: PV wire between tilted rows

    The PVC seems like it would work fine, but I don't like to use PVC in the sun since it will look bad after a few years.

    I could just do EMT with a connector and an insulating bushing on the connector to prevent abrasion.

    Meh, we'll see what happens next time it comes up. Maybe I'll post some pics. Actually, I'm thinking that on some job I should post a ton of pics and just open myself up to criticism.
  • a0128958a0128958 Solar Expert Posts: 316 ✭✭✭
    Re: PV wire between tilted rows

    Here's an example picture. See conduit in upper right corner, providing connection between PV panels on left and on right.

    original.jpg

    Hope this helps.

    Best regards,

    Bill
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: PV wire between tilted rows

    This is the job I was talking about. At first I had just run the wires across the rows, but I went back and redid it.

    tiltedrow1.jpg

    tiltedrow2.jpg

    I bent the EMT down at the end so water couldn't get or stay in (it's PV/USE-2 wire), put a plastic bushing on it and even secured it in a drip loop.
  • solarteksolartek Solar Expert Posts: 69 ✭✭✭✭
    Re: PV wire between tilted rows
    newenergy wrote: »
    This is the job I was talking about. At first I had just run the wires across the rows, but I went back and redid it.

    I bent the EMT down at the end so water couldn't get or stay in (it's PV/USE-2 wire), put a plastic bushing on it and even secured it in a drip loop.

    Are you grounding the EMT conduit between the rows?

    Scott.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: PV wire between tilted rows

    i don't know if i'd have bent the pipe upwards and then down as this could trap condensation in the rest of the conduit with no way to let it out.
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: PV wire between tilted rows
    solartek wrote: »
    Are you grounding the EMT conduit between the rows?

    Scott.

    Well, sorta but I could have done it better and maybe it's not required?

    250.136 A

    Basically, metal equipment secured to other metal equipment that's connected to the EGC is grounded, and the racking system is grounded. I'm sure, at least in it's present condition, if I test for continuity between the conduit and the EGC it would ring.

    250.96 Exception 2

    Short sections of metal enclosures or raceways used to provide support or protection of cable assemblies from physical damage shall not be required to be connected to the equipment grounding conductor.


    Still, I reckon running the EGC through each section of conduit and then putting a grounding bushing on the end would be better. Although, there really is hardly any chance of this ever causing a problem, not any more than a lot of other things like equipment grounding failure because of weathered compression fittings or something like that.
    niel wrote: »
    i don't know if i'd have bent the pipe upwards and then down as this could trap condensation in the rest of the conduit with no way to let it out.

    Not that I was thinking about condensation, but I don't think there are any traps in there. You can't tell from the picture, but the roof is sloped north about 5 degrees and the panels are tilted up to face south. Also, this is USE-2 in there.





    edit: I don't mean to be defensive. I want everything I do to be safe, to code and hold up for a long time.
  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: PV wire between tilted rows

    Looks good. I agree that it's not necessary to tie it in as part of the equipment ground if the PV frames (and thus the mounting framework) are properly grounded. (And besides, if you had used PVC, no one would have asked about grounding anyway.)

    Now for the little nit-picky stuff. :D

    When using 1-hole straps to secure a conduit, I don't put the screw *above* the conduit, I put it *under*. Sometimes, there is no choice, but usually there is. The problem with using a 1-hole strap "over the top" is that the first time someone accidentally puts a foot (or a knee, or a rump) on that EMT, the 1-hole strap will open up and the conduit will pop right out and slam down on the roof and according to law of Murphy, it will also yank that lo-vo wire hard enough to possibly cause what I refer to as "electrical excitement" (electrical excitement is why so very many electricians are nick-named "Sparky"). I can't see from where I'm sitting, but it looks like a 1-hole strap holding the EMT. If it is, then I would take it out, raise the conduit up a hair and use a 2-hole strap instead. Then if it gets stepped on, it will bend, but it won't yank that wire.

    My only other nit-pick is that I would have preferred to see the conduit a bit shorter, so that the loop of wire coming out the end could be tied to the framework down leg to maximally minimize :) the free-hanging loop. On general principles I dislike wire that swings in the breeze. Drip loops are, of course, sometimes necessary, but they should be made up of the shortest possible amount of free-hanging wire.

    Neil is correct that there is a potential water trap issue, but it looks like you've got that covered. I wouldn't sweat it - half of all the outdoor conduits I've ever seen had water in them and most of them worked just fine. You do what you can to keep the water out...and it goes where it wants anyway.
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: PV wire between tilted rows

    It is a one hole strap and that's a good point, thanks.

    Would you put silicone or something like that in the openings to seal that section of conduit?
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: PV wire between tilted rows
    solartek wrote: »
    Are you grounding the EMT conduit between the rows?

    Scott.

    I did another installation with separated arrays this week.

    groundedconduit.jpg
  • tallgirltallgirl Solar Expert Posts: 413 ✭✭
    Re: PV wire between tilted rows
    newenergy wrote: »
    I did another installation with separated arrays this week.

    Not sure I like the way you trapped that PV conductor between the ground wire and threads on the EMT fitting ...
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: PV wire between tilted rows
    tallgirl wrote: »
    Not sure I like the way you trapped that PV conductor between the ground wire and threads on the EMT fitting ...

    If it's about not being able to free it, the connector is within a foot or so and could be undone. If it's about rubbing, the only thing I was worried about was the edges of the grounding lug and the way the conductors are tied up they really can't do that.
  • tallgirltallgirl Solar Expert Posts: 413 ✭✭
    Re: PV wire between tilted rows
    newenergy wrote: »
    If it's about not being able to free it, the connector is within a foot or so and could be undone. If it's about rubbing, the only thing I was worried about was the edges of the grounding lug and the way the conductors are tied up they really can't do that.

    Thermal expansion of everything over time and those threads stripping the insulation off the conductor. I'd have looped to the outside of that and tied to the conductors to the left.

    But I can't see the big picture, so I dunno.
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: PV wire between tilted rows

    Interesting and I'll think about that next time. I think the thermal expansion for this length of everything (about 10m) is going to be less than .5mm even if there is a 50deg C change from cool night to hot day in the sun. And I don't think the wire is really pressed on the threads and the wire is certainly free to wiggle a bit.
  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: PV wire between tilted rows

    I gotta go with TG on that one - if nothing else, it looks a bit sloppy and I'm a neat freak when it comes to wiring.

    But hey, as long as the inspectors doesn't complain and the lights work...
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: PV wire between tilted rows

    I'm going to keep posting pictures until every single person says, "beautiful job!"
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: PV wire between tilted rows

    neatness is more what inspectors look for believe it or not. yes, you need to comply with the rules, but they may tend to fail a sloppy setup that technically meets the rules and overlook a minor oops on a neat setup and pass you. they have the power of nitpicking and that is what is reflected here by the responses you've gotten more than anything else. it just doesn't look neat looped through that way.
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: PV wire between tilted rows

    I install for a living and get inspected all the time and you guys are way pickier than inspectors, but it's all good. I want to do the best job I can.
  • russruss Solar Expert Posts: 593 ✭✭
    Re: PV wire between tilted rows

    neatness is so easy to see and sets the mood.

    The owner of plants İ used to build had no idea about the quality of work inside reformers worth 20 million dollars but he could see steps outside the firebox that were crooked. The steps were what he evaluated the entire reformer from.

    Neatness is important in many ways.
  • stevendstevend Solar Expert Posts: 34
    Re: PV wire between tilted rows

    First post from a newbie here. After reading this thread I'm leary of showing you this but here's what I had to do on a recent job. It's on the roof of an RV. I used Eternabond to tape the wires down. In my defence, the customer waited until just before he was leaving before parking it somewhere indoors where I could do the work (winter) otherwise I would have gone and shopped for something hard to put it in in case he steps on it. Though it was a roof, he'll be going up and cleaning the panels so I wanted to keep it low profile to avoid a tripping hazard. It's one of those things you look back at after a job and say, I wish I'd...
    S_IMG_0912_cr.jpg
    -Steve
    PS. Great forum. I'm picking up all kinds of tricks to use.
  • mike95490mike95490 Solar Expert Posts: 9,462 ✭✭✭✭✭
    Re: PV wire between tilted rows
    newenergy wrote: »
    I'm going to keep posting pictures until every single person says, "beautiful job!"

    I'm going to have to edit my photos !! Tough crowd here.
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    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
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  • tallgirltallgirl Solar Expert Posts: 413 ✭✭
    Re: PV wire between tilted rows
    dwh wrote: »
    I gotta go with TG on that one - if nothing else, it looks a bit sloppy and I'm a neat freak when it comes to wiring.

    But hey, as long as the inspectors doesn't complain and the lights work...

    Then I've =definitely= got to post some of my work. I don't get out the ironing board, but I do have a thing for straight lines and graceful curves.
  • dreesdrees Solar Expert Posts: 481 ✭✭✭
    Re: PV wire between tilted rows
    tallgirl wrote: »
    Then I've =definitely= got to post some of my work. I don't get out the ironing board, but I do have a thing for straight lines and graceful curves.
    What are you waiting for - let's see them. :) I think everyone here appreciates a nice clean install.
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