There is nothing wrong with lumber, I would use definitely consider using it with the following caution. There are several grades of treated lumber available. Typical treated lumber at the hardware store is generally more for indoor use as a bottom sil plate for framing and is most likely not #1 or better lumber. Just make sure whatever product you choose is graded and that you use the proper structural SPAN, weight loading charts for the particular product you are using.Good information, would you ever use treated lumbar with spanning rails such as the xr1000 as suggested ?
This may be worth checking out.Does anyone have recommendations for good ground mount systems ? I would like to do approximately 48 panels in some rocky soil
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I have the exact same problem. I borrowed a tractor mounted post auger to make the holes for my 10 panel rack. Well that went horribly wrong. Could only get maybe 10” into the earth before the rocks would stop me.in some rocky soil
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You are correct there are differences. Non ground contact meant for your sil plates and general outdoor deck construction where posts will stand on pier blocks. Ground contact where it is to come in contact with bare earth. Like 4x4 posts.There is nothing wrong with lumber, I would use definitely consider using it with the following caution. There are several grades of treated lumber available. Typical treated lumber at the hardware store is generally more for indoor use as a bottom sil plate for framing and is most likely not #1 or better lumber. Just make sure whatever product you choose is graded and that you use the proper structural SPAN, weight loading charts for the particular product you are using.
Good point , yes we have a frost depth of approximately 30”You don't mention what climate you're in. If you have frost depth, you either need piers that extend below the frost line or make one floating slab for the whole array to ride on top of. Piers in really rocky soil means you'll probably have to hire someone with a rock drill who can put in ground screws to the proper depth.
Does anyone have recommendations for good ground mount systems ? I would like to do approximately 48 panels in some rocky soil
Thanks
Just remember that if you're going with some type of surface mounting that we are worried about UPLIFT, not snow loading or foundation area.
Solar panels don't sink into the ground because of a bad foundation, they get ripped out of the ground because the wind wants to make them fly.
One fairly cheap way to make a surface base is to use concrete ballast blocks. Some 2x4's and plywood to make an 8 or 10 foot long block that is 2 feet wide and maybe 16 inches tall. Instead of filling it with solid concrete, you can dump in some busted concrete or large rocks. It doesn't need to be strong, just heavy. Fabricate some mounting studs for the pressure treated lumber or steel and you're all set.
Lumber is pretty expensive right now..
To avoid wind issues, I would enclose the mount and create local storage inside. Basically build a sturdy shed with a roof at the perfect solar angle.
I just spent two months after work, installing 20,600w or 48 ea QCells at 45° PV array angle on a shale/clay 36° slope, using 48 ea 4x4 post (8’-16’ L), sprayed termite spray, dried them sealed all posts with Black synthetic rubber, dug with post hole diggers/chisel as deep as possible, for shallow holes I poured concrete above ground inside a 12”-14” cylinder, Sealed top of concrete to posts with synthetic rubber, 34 pieces Unistrut, 22 ea 2x4x12’ bracing, 150+ lbs of concrete per post, 112 ea 3/8” x 2.5” ss bolts, 112 ea Belleville washers, 96 ea 3/8” x 4” galv lag bolts. It’s withstood 40 mph winds so far. Going around perimeter with 1x10 oak boards, spaced about 4” apart for a wind block, visual appeal, panel perimeter security and extra weight. Wiring now...Does anyone have recommendations for good ground mount systems ? I would like to do approximately 48 panels in some rocky soil
Thanks
I think since I am unable to dig that deep I’m going to do something like this but out of wood. I’m going to mount my panels landscape so their surface area is going to be 28’w by 7’ tall. How would I calculate how large to make my concrete blocks? I found a calculator for pounds per square foot. I’m thinking of probably 8 legs. 200# ea 300#?
This sounds exactly like what I was planning. Could you share some photos?I just spent two months after work, installing 20,600w or 48 ea QCells at 45° PV array angle on a shale/clay 36° slope, using 48 ea 4x4 post (8’-16’ L), sprayed termite spray, dried them sealed all posts with Black synthetic rubber, dug with post hole diggers/chisel as deep as possible, for shallow holes I poured concrete above ground inside a 12”-14” cylinder, Sealed top of concrete to posts with synthetic rubber, 34 pieces Unistrut, 22 ea 2x4x12’ bracing, 150+ lbs of concrete per post, 112 ea 3/8” x 2.5” ss bolts, 112 ea Belleville washers, 96 ea 3/8” x 4” galv lag bolts. It’s withstood 40 mph winds so far. Going around perimeter with 1x10 oak boards, spaced about 4” apart for a wind block, visual appeal, panel perimeter security and extra weight. Wiring now...
Very nice. This looks very similar to what I need. Cost?I used snapnrack.com for my ground mount.
Sandy soil here, boring piers was easy.
Rated for 170mph winds.
We get about 110-120 mph here in hurricanes, hope that the thing stays in place!
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However, on page 12 they also show a “beam footing option” that does not require deep holes.
It uses tons of concrete mass to keep the array on the ground in wind.