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diy solar

Panels on a retaining wall?

SolarPrep

Solar Enthusiast
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Jul 15, 2021
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Hope this is in the right part of the forum. Has anyone mounted a solar array to a large retaining wall? Our is the type with the super heavy poured concrete blocks that vary from 3+ tons each to .4 ton each. My thought is to fab up some triangles out of aluminum, and use heavy expansion bolts to mount 72 cells panels in portrait to the face of the blocks. Our wall varies from 7' to 11' in the area where panels would be, and we would not attach into the top blocks, because they are the most likely to settle over time. If we trimmed back a few over-hanging trees, we could get enough panels on this wall to offset all our electrical needs.

Did think about making provisions to account for slight settling, like slotted vertical rails. Another thought is to drive ground screws in a few feet from the base to hold the bottom of any rail, and just one brace into a mid to upper block for support. Because the wall curves, initial thoughts are that each mounted group of panels might only be 3 wide.

Any thoughts? Concerns?

Happy Turkey Day!
 
I don’t see a problem with it , I build a lot of big walls .
if the wall was built rite it should not sink at all .
I’ve never seen 3 ton blocks ?
Most residential walls use small 80lb blocks to 800/1000 lbs
I’ve seen guys mounting big 36+ panel array on the 2 800lb blocks every 10 feet I think there where 10 blocks .
I think if you have large blocks on top I would want a L shaped bracket on top so the array is not hanging from the bolts .
I would rather see galvanized steel brackets .
If the wall is steped back 1” you could sit the bracket on top of the step .
You could hit a 6000lb block with a air plane it not going any where .
 
Wellbuilt: I had not thought about galvanized. That is a good idea. These blocks all have the same face size....16" x 48". They vary in depth up to 7' deep. (Front edge to back edge) The sides are truncated. They do step back slightly. so a foot might work, as you suggest. As you go up the wall, the depth of the blocks decreases. The wall is built on 2' of compacted gravel, and back-filled with gravel. It isn't going anywhere.

As for the bolts, I was thinking large diameter. At least 5/8", maybe 3/4". If we mounted them in frames of 2-3 panels each, I'm sure that would suffice. There would not be a lot of wind load, because the wall is on the lower side of a sloping hill.

Thanks for the suggestions!
 
I would think a support every three panels would be good that’s 10 feet
I would use a few smaller Anchors rather then one big one .
I use 31/2” bolts 3/8 “ wide most of the time if you went up to 1/2” I would use 4” long bolts
5/8 would be 5” deep .
I would allso epoxy the bolts in and use bolts with a full expanding sleeve .
The epoxy will stop the bolts from working louse in the wind .
 
Wellbuilt: more good ideas..thanks! I have a whole bunch of large anchors that I picked up for next to nothing, but the sleeve is only about 1". I have them from 3" up to about 6" long. Good quality, American made believe it or not. I like the idea of using epoxy.

Been thinking about anchoring at the top. The top row have about a 4' indentation so you can fill them with dirt and bring your landscape up almost to the face of the wall. I have thought about making an L shaped foot, and drilling down into the block to anchor it, but was worried about corrosion. The top blocks can tip very slightly if you get a really active groundhog that takes up residence. So far we haven't seen that, but the entire wall is built where they were really active in the past I was a bit concerned that a block could put some backward pressure on a frame of panels.

My initial thought was to not have the panels stick up above the wall. But now, I'm wondering if it might not be a good idea. They would get more sun, and could serve dual purpose as a sort of fence. This wall is cut into a hillside, and there is nothng to prevent a person or animal from falling off the wall. Although where it is located, is not a traffic area. We do have a LOT of deer though. The best part of this wall mount idea is that it would use an area that is just going to waste, conduit could be bent in a gentle radius and be attached to the block, and you can reach any of this with a long broom standing on teh ground. No holes in the roof.
 
The cost of the Anchors won’t help you if the panels blow off .
The epoxy mite hold them , I would use the longer bolts you have .
A new idea , we build long tall walls and drill posts in the top and epoxy them in
You could use the posts to hold the top of the panel support .
 
Wellbuilt: How thick are the blocks at the top of your wall? On our top blocks that have the cast indentation, the concrete is between 12"-13" thick. How deep would you put the posts? Are you talking pipe? I have ready, cheap access to heavy wall stainless pipe, especially in lengths 2'-4'. Are you suggesting I use the pipe for a fence, and attach the top of the panels too? That could work. I tend to think of stainless, because it is readily available to me, but galvanized would be fine too.

We have some stainless all thread (5/8" x 12" and 1" x 16") sitting on the shelf here that could also provide a strong anchor point. Right now, the biggest hammer drill bit I have is 1.5" spline drive. I could rent a larger bit, but might just check out Harbor Freight. I've had good luck with their smaller bits where we assumed they would be throw aways, but they have held up really well. Surprise Surprise.

Any particular brand of epoxy that you have had good luck with?

Your help is appreciated. Haven't done much work with epoxy, and although I have installed a lot of concrete anchors, they were mostly inside.
 
the top of the walls could be 18/24” you could rent a core drill from united rental with hammer drill .
You drill can drill 2 “ hole for sch 40 pipe .
I think 2” sch40 should be heavy enough 4’ high with 5 foot pipe so12” that is what we do .
They make epoxie for glueing rebar into rock that is what I would use ,get it from a mason yard .
Put some in the hole then wet the plot or pipe you should see a little come out the top .
I was thinking of maybe a three point support 3’ up on the pole and one at the bottom of the panel and some thing bolted to the top of the block ?‍♂️
 
Wellbuilt: Thanks. Appreciated!

Didn't think about a core bit. One of my buddies has those up to 6", if he happens to be around. But, renting one is cheap too. My drill can easily handle a 2". The blocks have an inverted pyramid on the bottom, and a corresponding up-facing pyramind on the top so they kind of self align. Except for the top row, which are just indented for dirt to fill up the space. I could core-bit down even into the block below if necessary, but would have to go about 20" over all to make it into the second block about 6".

Thanks again.
 
Do you have any pics of the completed project? Mounting to a retaining wall would work in my situation.
Hope this is in the right part of the forum. Has anyone mounted a solar array to a large retaining wall? Our is the type with the super heavy poured concrete blocks that vary from 3+ tons each to .4 ton each. My thought is to fab up some triangles out of aluminum, and use heavy expansion bolts to mount 72 cells panels in portrait to the face of the blocks. Our wall varies from 7' to 11' in the area where panels would be, and we would not attach into the top blocks, because they are the most likely to settle over time. If we trimmed back a few over-hanging trees, we could get enough panels on this wall to offset all our electrical needs.

Did think about making provisions to account for slight settling, like slotted vertical rails. Another thought is to drive ground screws in a few feet from the base to hold the bottom of any rail, and just one brace into a mid to upper block for support. Because the wall curves, initial thoughts are that each mounted group of panels might only be 3 wide.

Any thoughts? Concerns?

Happy Turkey Day
 
Mounting a solar panel on the retaining wall is a very good idea, and I recommend you do it. The most important step is to mount the panel correctly, and that's it. You will see how effective this solar panel will be, especially in cold weather. But I do not recommend you do it alone. It would be best to seek specialists' help to ensure that the result will be correct and qualitative. I also installed some solar panels with the help of specialists from Almighty Construction, and I am very satisfied with the result and effect.
 
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