solar array grounding?

In setting up my solar panel array, do I need to have a grounding lug on each and every single panel and rail section to meet code? also, what type of wire is the least expensive to do this with? I got some number 6 bare stranded wire but it's super expensive and I see a lot of guys using what looks like single conductor number 10.

thanks!

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: solar array grounding?

    Each panel frame and the array mounts should be tied together electrically for ground. Code requires a connector to any part that is "mechanically separate" and that means you aren't supposed to rely on mounting bolts/clips to make the conductive connection.

    It isn't a matter of what wire is cheapest for this, it's what wire meets the specifications. In most jurisdictions you'll find that is bare #6 stranded, with no "detachable" splices.

    To be sure your design meets local code, ask the local inspector.
  • jaggedbenjaggedben Solar Expert Posts: 230 ✭✭
    Re: solar array grounding?

    The alternative to putting a ground lug on every panel and piece of rail is to use WEEBs, or listed bonding jumpers for rails.

    If you use lugs, they need to be a suitable type. The standard is a tinned copper lug with stainless steel set-screws, direct burial rated.

    Where I work it is acceptable to use #10 bare solid copper. But you need to ask your local inspector.
  • differentdifferent Registered Users Posts: 12
    Re: solar array grounding?

    I don't think WEEBs will work in my situation anyway because I am using rails that use a channel nut that slides in from the end for each panel mount. It won't do me much good to get an electrical connection from the panel to a channel nut and it still isn't bonded to the rail.

    Does anyone know a good outlet for bonding jumpers? and since WEEBs won't work for the panels, can I just use those jumpers between each panel as well as each rail and then at the end of the array run down to the grounding rod with whatever the inspector says I need?

    thanks again for the help!
  • jaggedbenjaggedben Solar Expert Posts: 230 ✭✭
    Re: solar array grounding?
    different wrote: »
    I don't think WEEBs will work in my situation anyway because I am using rails that use a channel nut that slides in from the end for each panel mount.

    If your racking is made specifically for solar then you can ask the manufacturer if there is a WEEB that is listed for use with it. If not, then indeed you can't use WEEBs.
    and since WEEBs won't work for the panels, can I just use those jumpers between each panel as well as each rail and then at the end of the array run down to the grounding rod with whatever the inspector says I need?

    This is not advantageous for the panels. The cost of a lug and 4ft of wire (even #6) is less than that of a bonding jumper. You will have more screws to install and a harder time doing so. And you will have many more points of failure that could result in unbonding multiple panels at once. The same applies if you ever have to remove a panel for servicing; you will be unbonding all the panels connected to it, instead of leaving them bonded to a continuous copper EGC (and which BTW would also be a code violation unless you added a jumper in place of the panel).

    Using bonding jumpers for the rails might be more advantageous, since you can save more wire. But since you are apparently not using one of the common solar-specific racking products, it may not be that any bonding jumper is approved for use with your racking. (Are you using steel or aluminum?)
  • differentdifferent Registered Users Posts: 12
    Re: solar array grounding?

    My rails are specifically made for solar. They are aluminum. These are the rails I have.

    http://www.prosolar.com/prosolar-new/pages/rooftrac-main2.htm
    jaggedben wrote: »
    If your racking is made specifically for solar then you can ask the manufacturer if there is a WEEB that is listed for use with it. If not, then indeed you can't use WEEBs.



    This is not advantageous for the panels. The cost of a lug and 4ft of wire (even #6) is less than that of a bonding jumper. You will have more screws to install and a harder time doing so. And you will have many more points of failure that could result in unbonding multiple panels at once. The same applies if you ever have to remove a panel for servicing; you will be unbonding all the panels connected to it, instead of leaving them bonded to a continuous copper EGC (and which BTW would also be a code violation unless you added a jumper in place of the panel).

    Using bonding jumpers for the rails might be more advantageous, since you can save more wire. But since you are apparently not using one of the common solar-specific racking products, it may not be that any bonding jumper is approved for use with your racking. (Are you using steel or aluminum?)
  • jaggedbenjaggedben Solar Expert Posts: 230 ✭✭
    Re: solar array grounding?
    different wrote: »
    My rails are specifically made for solar. They are aluminum. These are the rails I have.

    http://www.prosolar.com/prosolar-new/pages/rooftrac-main2.htm

    Then you should be able to use the WEEB-PMC, which is specifically for Pro Solar rail.

    It would also be advisable to find the installation manual for your panels and see if WEEBs are described as an approved grounding method. Some inspectors will prohibit weebs if this is not the case. Others will allow weebs without expecting that.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: solar array grounding?
    Each panel frame and the array mounts should be tied together electrically for ground. Code requires a connector to any part that is "mechanically separate" and that means you aren't supposed to rely on mounting bolts/clips to make the conductive connection.
    True, unless they are UL listed as a grounding connection. Some are.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: solar array grounding?
    ggunn wrote: »
    True, unless they are UL listed as a grounding connection. Some are.

    Which is why code is never simple. ;)
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: solar array grounding?
    Which is why code is never simple. ;)
    Especially when it comes to grounding issues.
  • solarixsolarix Solar Expert Posts: 713 ✭✭
    Re: solar array grounding?

    #6 Bare copper is required when the use is subject to damage, ie. exposed. In areas like beneath areas, it can be as small as the conductors (#10) being protected.
    Iron Ridge has just come out with a neat system of array grounding where the panel clamps have teeth on them and are rated for this use. This eliminates all the ground lugs except one per pair of rails, but still have to splice all the rails together. One of the problems we have with regular ground lugs is that once attached to the panel, you can't lay the panel down on the roof with out the lug chewing up the shingles. Can't stack them either.
    Why is it that the solar industry is required to use expensive solid copper ground lugs when the cheap aluminum kind is fine everywhere else? Take for example the POS used on your basic ground bushing for grounding EMT. I hate those ground bushings. Nasty to install in tight places, generally are required on both ends of the conduit if has a GEC in it, and questionable how well they will work. Is there a better way?
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: solar array grounding?
    solarix wrote: »
    Why is it that the solar industry is required to use expensive solid copper ground lugs when the cheap aluminum kind is fine everywhere else?
    You cannot use the unplated copper ones, either, because you cannot directly electrically connect copper to aluminum outdoors. It corrodes.
  • jaggedbenjaggedben Solar Expert Posts: 230 ✭✭
    Re: solar array grounding?
    solarix wrote: »
    Iron Ridge has just come out with a neat system of array grounding where the panel clamps have teeth on them and are rated for this use. This eliminates all the ground lugs except one per pair of rails, but still have to splice all the rails together.

    Yes, they've basically taken the WEEB approach but eliminated the WEEBs themselves. So far I've liked what I've seen, although the clamps do seem to seize more readily than before.
    Why is it that the solar industry is required to use expensive solid copper ground lugs when the cheap aluminum kind is fine everywhere else?

    The tin plating is a sacrificial layer. Too much exposure to water and it disappears, and then for all practical purposes the lug is no longer rated for both Cu and Al. I have seen enough of these lugs in the wild to tell you they don't look pretty after a few months. Both with stainless steel set screws and without.

    And it is not just the solar industry that is required to use them, it's anyone who installs lugs that are exposed the elements.
    ggunn wrote: »
    You cannot use the unplated copper ones, either, because you cannot directly electrically connect copper to aluminum outdoors. It corrodes.

    I happen to think that unplated copper would be just fine, if separated from the rails with a stainless steel washer. In fact, I do the stainless steel washer anyway on the tin-plated ones, because the tin plating disappears as mentioned above. (It disappears faster without the washer.) A few years ago Wiles was recommending simply clamping ground wire between two stainless washers. I know he's changed his mind, but if that was good enough then...

    I have not ordered unplated lugs yet because the cost savings so far wouldn't be enough to justify one argument with an AHJ. (Which is partly because we use mainly WEEBs.)
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: solar array grounding?
    jaggedben wrote: »
    I happen to think that unplated copper would be just fine, if separated from the rails with a stainless steel washer. In fact, I do the stainless steel washer anyway on the tin-plated ones, because the tin plating disappears as mentioned above. (It disappears faster without the washer.) A few years ago Wiles was recommending simply clamping ground wire between two stainless washers. I know he's changed his mind, but if that was good enough then...
    )
    I've used SS washers to separate copper grounding lugs from aluminum frame of my PV array, been exposed to all Nature could throw at them since 2007 and no sign of corrosion so far. Oh, and yes, SS nuts and bolts as well of course.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: solar array grounding?
    I've used SS washers to separate copper grounding lugs from aluminum frame of my PV array, been exposed to all Nature could throw at them since 2007 and no sign of corrosion so far. Oh, and yes, SS nuts and bolts as well of course.
    I can see the bumper sticker now:

    SOLAR INSTALLERS HAVE STAINLESS STEEL NUTS

    :D
  • differentdifferent Registered Users Posts: 12
    Re: solar array grounding?

    So in my case what is the least expensive way for me to ground my array if WEEBs don't in fact work? does anyone have any links to anything affordable?

    thanks guys
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: solar array grounding?
    ggunn wrote: »
    I can see the bumper sticker now:

    SOLAR INSTALLERS HAVE STAINLESS STEEL NUTS

    :D

    Borderline, but i liked it. at least it's clean as there's plenty of washers.:p
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: solar array grounding?
    niel wrote: »
    Borderline, but i liked it. at least it's clean as there's plenty of washers.:p
    You oughta ban yourself for that pun.
  • jaggedbenjaggedben Solar Expert Posts: 230 ✭✭
    Re: solar array grounding?
    ggunn wrote: »
    I can see the bumper sticker now:

    SOLAR INSTALLERS HAVE STAINLESS STEEL NUTS

    :D

    I'd buy one. Not sure why my wife would think, or (alternatively) if the boss would have us put it on the truck. But I'd buy one.
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: solar array grounding?
    ggunn wrote: »
    You oughta ban yourself for that pun.

    i did as i wasn't here yesterday.:cry: am i forgiven?:p
  • BB.BB. Super Moderators, Administrators Posts: 29,497 admin
    Re: solar array grounding?

    I vote for more Pun-ishment.

    -Bill :p
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: solar array grounding?
    BB. wrote: »
    I vote for more Pun-ishment.

    -Bill :p

    keep that up and i will extend my pun-ishment.:p
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: solar array grounding?

    All pun, No action?
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: solar array grounding?

    aw razzberries to you. :p:p:p
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: solar array grounding?
    niel wrote: »
    aw razzberries to you. :p:p:p
    You are having too much fun!
    "All work and no play makes jack."
    SMA SB 3000, old BP panels.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: solar array grounding?
    inetdog wrote: »
    You are having too much fun!
    "All work and no play makes jack."
    All play and no work makes Jack unemployed.
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