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  • ground-mount installation with wooden framing ?

    I am looking to do a small ~5kw ground-mount system at my house. I'd like to be able to use the area under the panels for storage of trash cans, bikes, and such (understanding that they won't stay completely dry due to the difficult of reliable seals between panels). I'm thinking to arrange the panels in a roughly square 5x3 panel configuration, in "portrait" mode, so that when you're standing south of the array and looking northward at it, you see 3 rows of 5 panels each.


    My understanding is that on roof-mount systems, there are usually two aluminum rails for each row of a panels, as I've shown. These rails are screwed to house rafters, and panels are bolted or clamped to them.

    I would like to build the thing completely from wood. So I'd have posts at the 4 corners of the array, bolted to concrete piers (with embedded J-bolts). I'd run beams between posts along the west and east sides, and some bracing along the north and south sides. The I'd simply run 2-by boards between the west-side and east-side beams; these boards would be located where the aluminum rails (shown on my drawing) are located. Seems to be this would be cheaper and simpler than using metal rail systems.

    Does this make any sense ?

    How would I attach the panels to the wooden rails ? I've been looking an the installation manual for some Solaria panels I'm considering: https://static1.squarespace.com/stat...ion+Manual.pdf
    and there appear to be 4 mounting slots, 2 along each long side of the panel. Seems like I'd need to somehow run lag screws through these slots into the wooden boards. But how do I access this ? I can't quite visualize it, but I can't figure out how the metal screws alluded to in the manual are attached either. I guess I just need to see an installation in person and maybe it'd suddenly make sense to me.
    Attached Files

  • #2
    It would be a lot simpler if you did it all with wood EXCEP use the rails. This will help with attachment, make it stiffer and less likely to break as well as help with grounding the PV modules.
    The rails do not cost all that much
    OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

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    • #3
      Originally posted by ButchDeal View Post
      It would be a lot simpler if you did it all with wood EXCEP use the rails. This will help with attachment, make it stiffer and less likely to break as well as help with grounding the PV modules.
      The rails do not cost all that much
      So just run beams between posts along the north & south sides, then run however many "rafters" (running N-S) are needed to support the metal rails' allowable spans, and then attach the metal rails (running E-W) to these rafters.

      I still don't understand how the panels attach to these rails. That manual talk about four SS bolts (I thought SS and aluminum were a bad match as far as galvanic corrosion). Do you install the bolts from above or from below ? On a regular roof mount, how on earth would you access them from below ?

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      • #4
        Here is one construction of a 2 sided treated wood array, 12KW, now 6 years and counting. Bolts
        are hot dipped galvanized, a long 18-8 SS bolt holds the aluminum to the wood. 6061 aluminum
        is held with 18-8 hardware. Wood and aluminum do not like contact, there is a big linoleum washer
        between the wood and the aluminum. Bruce Roe

        NSbuba.jpg
        NSAend.jpg
        NSAjig.jpg
        Last edited by bcroe; 10-25-2019, 11:20 PM.

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        • #5
          Originally posted by bcroe View Post
          Here is one construction of a 2 sided treated wood array, 12KW, now 6 years and counting. Bolts
          are hot dipped galvanized, a long 18-8 SS bolt holds the aluminum to the wood. 6061 aluminum
          is held with 18-8 hardware. Wood and aluminum do not like contact, there is a big linoleum washer
          between the wood and the aluminum. Bruce Roe
          Ok, but you're still using a wood structure, and then attaching "conventional" (like would be used on a roof-mount) aluminum rails to the wood and attaching the panels to the rails ?

          As far as corrosion, SS and aluminum are a bad pairing for galavnic corrosion too.



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          • #6
            Originally posted by RShackleford
            Ok, but you're still using a wood structure, and then attaching "conventional"
            (like would be used on a roof-mount) aluminum rails to the wood and attaching the panels to the rails ?

            As far as corrosion, SS and aluminum are a bad pairing for galavnic corrosion too.
            NOTHING here is like conventional roof mount hardware. Those are stock 6061 angles, with
            holes drilled as needed. I doubt the usual stuff is that good? No slots anywhere, panels are
            BOLTED on from the rear, not clipped over the top.

            Only about 300 feet of aluminum angle used, still not cheap. Delivered free by my local metal
            supplier, in max 25 foot sections. After 6 northern IL winters there is no trace of corrosion on
            the bolts, anything will easily come apart. A lot of that sort of thing happens here with the
            experiments. I use double nuts as locks.

            As for the treated wood, anything going thru it soon becomes locked in place. A bolt will
            twist off before coming out. good luck, Bruce Roe

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            • #7
              Originally posted by bcroe View Post

              ... panels are BOLTED on from the rear, not clipped over the top.
              Yeah, that clipped over the top (IronRidge UFO part) seems somewhat sketchy.

              I still can't figure out you do the bolting. There aren't threaded holes in the rear of the panels, are there, just slots.

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              • #8
                Originally posted by RShackleford
                Yeah, that clipped over the top (IronRidge UFO part) seems somewhat sketchy.
                I still can't figure out you do the bolting. There aren't threaded holes in the rear of the panels, are there, just slots.
                All my panels have holes in the back, a couple inches behind the front. The rails were spaced to
                line up, 4 bolts with nuts goes through both. Washers spread the stress. In some cases I drilled
                new holes where I wanted them.

                That jig in the last pic clipped onto the rail, to help hold those 65 lb panels in place till I got the
                bolts started. Then it would be slid along to the next panel. Bruce Roe

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                • #9
                  Originally posted by bcroe View Post
                  All my panels have holes in the back, a couple inches behind the front. The rails were spaced to
                  line up, 4 bolts with nuts goes through both.
                  So since your system is ground-mount, you're able to reach in to the other side of those holes and thread a nut onto your bolts ? I guess I could do that with the system I'm doing too, even if it's not exactly ground-mount (more like a leaky shed roof). Main reason is to save money, right, cheaper than the IronRidge stuff (plus all the other little fittings you have to buy for those rails to work right).

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                  • #10
                    I did not reach around to the other side, I stood back there to do the work. If you are not really
                    doing a ground mount, this may not work for you. The commercial roof mount stuff is designed
                    so an experienced crew can mount panels from the front with a minimum of time and labor. It
                    is not especially designed for ground mount, for repelling snow, for a one man crew, and esp
                    not for a movable array. I like mine better. Bruce Roe

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                    • #11
                      Originally posted by bcroe View Post
                      I did not reach around to the other side, I stood back there to do the work.
                      I meant reaching around to the far/front side a "lip" on the back of the panel. Since I haven't yet seen a panel in person, I'm just having to imagine ...

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                      • #12
                        My pole mount and my wall mount both used superstrut for attaching the panels. Superstrut is zinc plated gold colored version of Unistrut, a bit smoother than standard strut. I used standard strut nuts without springs to secure the panels to the strut. My panels like many panels have an aluminum angle frame with a lip on the back spaced out about 1.5" back from the face of the panel with holes predrilled for back mounting the panels. The depth of the gap between the panel face and the rear lip can vary but structurally it needs to be minimum amount to make the panel assembly strong enough to span between supports for snow and wind loading. The tough part is that that gap is tight for folks like me with big fingers. The bolts, washers and lock washers have to be slipped into the gap then down through the hole and line up with the strut nut in the channel. Lots of degrees of freedom for things to go wrong. I buy SS hardware by the box but recomend a tarp under the array as its easy to drop hardware into the grass where it disappears. Once I got things lined up and hand tightened then I have to use small wrench to tight up bolts a little bit at time.. On my older wall mount I did not worry about possible galvanic action and its about 15 years old with no real evidence of corrosion. I live inland and out in the woods so the atmosphere is not aggressive. On my newer pole mount I bought UHMW plastic sheet and hand cut some square washers" with a slot cut in one side to allow me to slide them on after the bolt is started. Once I get the panel bolts started,I slide the "washers" on and then tighten the bolts so the aluminum frame is isolated from the unistrut. Note you can buy stainless strut but its special order and expensive. One trick I figured out is its quicker to start the the bolts on the speed nuts while sitting on the ground. I then would slide the entire panel with the strut nuts hanging down loose and rotated 90 degrees so they dropped down through the slot in the strut then rotated them through a strut hole with a screwdriver. It was lot faster than trying to hold the panel in place and threading everything down and in place on the strut.

                        I am not worried about anyone stealing the panels as unless they want to permanently damage the panels it takes a long time to remove one due to the lack of clearance.

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                        • #13
                          Originally posted by peakbagger
                          My pole mount and my wall mount both used superstrut for attaching the panels.

                          One trick I figured out is its quicker to start the the bolts on the speed nuts while sitting on the ground. I then would slide the entire panel with the strut nuts hanging down loose and rotated 90 degrees so they dropped down through the slot in the strut then rotated them through a strut hole with a screwdriver. It was lot faster than trying to hold the panel in place and threading everything down and in place on the strut.
                          That sounds like a pretty tricky operation. I just set a panel on that bottom jig in my last pic,
                          wiggled it a bit to get bolts thru holes, and slid that jig to the next position before tightening
                          up the bolts. Bruce Roe

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                          • #14
                            FWIW, and if you're interested, I constructed this all wood 4k watt frame for less than $400 that hasn't been touched since I walked away from it 2 yrs. ago. Doubt it will last 20 more, but neither will I.













                            Last edited by MrDodge; 10-28-2019, 12:44 AM.

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                            • #15
                              Originally posted by MrDodge View Post
                              FWIW, and if you're interested, I constructed this all wood 4k watt frame for less than $400 that hasn't been touched since I walked away from it 2 yrs. ago. Doubt it will last 20 more, but neither will I.
                              Hmm that pic did not come thru for me. Bruce Roe

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