Mounting panels with unistrut

[Skypower]

Just avoid the jello jiggles. Short corner braces are useless as in the first picture. From highest corner to lowest point will get you rigidity as seen in the last two pictures. Even if you extend short pieces to do it, its worth it(last picture) It also won’t take as many braces to do it.

 

[Hedges]

How much resistance to uplift does your design have?

 

[Skypower]

How much resistance to uplift does your design have?

View attachment 171227

Gravity ?

 

[Skypower]

How much resistance to uplift does your design have?

View attachment 171227

It’s between the house and a newer fence so it’s well sheltered. It’s only got to last a few more years at this location then it’ll either be disassembled and go with or more likely given to a buddy to make it go away before the next owner gets it. Think of it as a way to get my feet wet in solar. We had heck of a wind storm last winter and went out to see how stable it was and it seemed like everything else was moving but that. If this was out in the open your damned right it would be anchored in the ground and probably an engineered mounted system. If this heavy low angle panel thing lifts at this location, it would have to be an F3+ tornado which we just don’t get here. But yeah, your eyes are good.

 

[DrewLoker]

For the end panels where there's only 1 edge and the square hold-down doesn't have 2 panels to hold 'flat', I used a strut near the edge but completely under the panels. Used a piece of semi flattened EMT conduit to provide a base for the square hold-down to lay flat and not tilt off the edge of the panel.
View attachment 161272

I am re-examining your solution. I came up with something from seeing your solution initially based on what I had on hand, but it is not acceptable. I cut 1/2" PVC pieces at 1.5". The problem is the 1/2" doesn't fit well as it doesn't sit flat inside of the plastic ring with nut, and each piece I cut varies a bit.

So, I need to come up with something else. I see what I missed the first time of your...something under the panel, on top the strut. But I don't have much extra bolt to put too much there. The 2.5" bolt is not long enough for much to go under another 2mm thick washer.

So, I am trying to think of another piece I could put between the top square washer and rail. Maybe 3/4" PVC?

Any other ideas from others for the End Mounts?

Thanks!!

 

[OffGridInTheCity]

I am re-examining your solution. I came up with something from seeing it initially based on what I had on hand, but it is not acceptable. I cut 1/2" PVC pieces at 1.5". The problem is the 1/2" doesn't fit well as it doesn't sit flat inside of the plastic ring with nut, and each piece I cut varies a bit.

So, I need to come up with something. I see what I missed the first time of your...something under the panel, on top the strut. But I don't have much extra bolt to put too much there. The 2.5" bolt is not long enough for much to go under another 2mm thick washer.

So, I am trying to think of another piece I could put between the top square washer and rail. Maybe 3/4" PVC?

Any other ideas from others for the End Mounts?

Thanks!!

I used metal EMT conduit, flattened into an oval. I used the square mounting pieces under (and over) the EMT.


In another array/area I used these adjustable edge mounts to hold the edge down against the unistrut - had to fiddle a bit to attach to the unistrut but they are adjustable so I could find a solid fit.

Solar Panel Mounting Brackets-Adj End Clamp fit 35mm to 50mm -Pack of 20 | eBay

They are clear mill finish.

www.ebay.com

 

[DrewLoker]

Thanks the additional info. I had missed that you used an extra square mounting piece...thought you had stated it was something else even though it looked like another square. Makes sense. What size bolt did you use? I bought a box of 2.5", but may just need to buy some 3" singles. I don't think 2.5" is going to go through another square and have enough threads to get through the nut. I did put a lock washer also above the top square. Those squares are THICK!!

 

[OffGridInTheCity]

Thanks the additional info. I had missed that you used an extra square mounting piece...thought you had stated it was something else even though it looked like another square. Makes sense. What size bolt did you use? I bought a box of 2.5", but may just need to buy some 3" singles. I don't think 2.5" is going to go through another square and have enough threads to get through the nut. I did put a lock washer also above the top square. Those squares are THICK!!

Yea - I had about 3 lengths of bolts. Don't remember the details but it's details like this that just drive me crazy sometimes

 

[DrewLoker]

Yea - I had about 3 lengths of bolts. Don't remember the details but it's details like this that just drive me crazy sometimes

If my panel is 1-3/8, how thick should thick should the spacer be?

 

[OffGridInTheCity]

If my panel is 1-3/8, how thick should thick should the spacer be?

The EMT tube - you cut so the top washer is 'roughly' flat - so the distance from the base to the edge of the panel. I used a hack saw and got it on the 2nd try.

 

[DrewLoker]

I used a hack saw and got it on the 2nd try.

Well, it doesn’t look like it, but the end mounts are way better now. At least I feel better about the panels up on the roof. Thanks.

I dont know why using a hacksaw has to be so inconsistent…all 8 were slightly different. I need to go get some more square washers.

 

[OffGridInTheCity]

Left looks perfectly good! The right is OK as long as it stays snug but it's pretty cockeyed. My array has been up 4+ years and all has stayed snug - I worried too much when building it.

I hate to say this but it occurred to me that you if you have access, you could drill a hole in the bottom flange of the panel (underneath the panel) and bolt to the Unistrut.

 

[Hedges]

Left looks perfectly good! The right is OK as long as it stays snug but it's pretty cockeyed.

Bolt pulls toward channel. PV frame pushes away. I'd like to see a second object on opposite side of bolt also pushing away. For instance, flip over one of these and use as the clamp.

 

[DrewLoker]

I'd like to see a second object on opposite side of bolt also pushing away.

Thanks for the suggestion…do you happen to have a picture of what that would look like?

Sorry for the confusion. The left, gray pipe, is the second attempt. The white PVC was my first attempt that I didn’t feel good about…mostly because of a lack of an under panel washer to create that base. But also because I could not get the metal pipe cut exactly perfect. I ended up with eight odd ball sized skewed pieces, especially when I went to make it oblong. I did better on 2-8. I’ll cut another piece for that first one again as that seems to be the trick to get the top washer flat.

I feel good about the ends at this point. Except one other concern is if I tightened them down enough…or too much.

Is the glass on a panel tempered? I tighted until I felt that the lock washer was secure…but I also felt that the frame was starting to push against the glass…too much. I almost feel like there needs to be a rubber base between the washer and the frame.

Thoughts on that?

Thanks for y'all's time!!

 

[Hedges]

I understood panels with wafers were laminated to tempered glass (stronger) while thin-film was on non-tempered glass (temperature of thin-film process would alter tempering.)

However, Tim was able to put a hole for vent pipe through a defective panel:

DISCUSSION: PV Series vs. Parallel. Is parallel REALLY better for partial shading situations?

3/23/23 EDIT: Will posted some interesting results: https://diysolarforum.com/threads/series-string-shading-summed-up-in-4-pictures.60158/ I'm thinking series is better. Here's why: Typical 60 cell panel with bypass diodes: I think everyone can accept that this panel will lose 1/3 of its...

diysolarforum.com

If frame is clamped to rail with pressure on edge of frame (about 1" across), it shouldn't deform much. But frame is narrow there, and clamp reaches in toward offset with glass. The Unirac bracket below with double step might be less likely to do that, can't tilt.

My Unistrut angle piece idea is like this, might need to cut to be just taller than panel frame.




One edge of angle contacts mounting rail, serves as a fulcrum for angle to tilt and bear down on panel frame.

Unirac versions:







You might accomplish similar using the square piece for horizontal (under bolt and over panel frame), and pipe/conduit for vertical, by cutting a step in the top of pipe. Bolt goes through middle of pipe like before, but your square piece only contacts pipe where elbow of the angle shown above would be. Point of contact between plate and pipe is a fulcrum, and bolt tilts plate down to bear on PV panel frame.

 

[Hedges]

But I think your round pipes can also work fine. Need to be slightly shorter than panel frame, and bolt centered in pipe or towards panel side. That way bolt pulls down middle of plate, which bears on frame to one side, pipe to the other.

If it was big enough to ride on the Unistrut rail (maybe rectangular), that would be good. But then square plate corners might miss it. So you've got the washer underneath.

Difficult to find random hardware that does just what you want.
When I assembled additional Unirac U/LA mount, I bought aluminum angle from McMaster, drilled holes and cut with saw. Those were for rails to piped, not frames to rails (which I bought from Unirac.)

The Unistrut angles I suggested might work better if instead of simply shortened to match panel thickness, they were cut with a step to fit inside channel. Maybe two drilled 1/4" or 3/8" holes then sawed, so they hook on both rolled edges of strut.

 

[Surferdudemi]

I looked at those yesterday as I had the same question on how to mount to unistrut, or some variation of unistrut. They are made by a company called Power Strut. Their web page for those mounting brackets can be found here: https://www.power-strut.com/docs/li...r-components-sell-sheet.pdf?sfvrsn=f6f6606e_2

It appears to me that most mounting solutions that use unistrut are just hold downs. These hold down brackets don't use fasteners to attach to the solar panel itself. That bothers me. I see no reason why the mounting brackets from Rich Solar couldn't be used on unistrut. I think it is a much more cost effective solution.

Use of the above brackets depends on the orientation of your unistrut. If the unistrut is running perpendicular to the solar panel then the most likely way to use these brackets would be on the top and bottom rails of the panel.

Alternatively, you could use these brackets - also from Rich Solar - anywhere in any orientation.

Clamp / hold down brackets, like Unirac, work fine with no other mechanical connection to the panels, torqued to spec. Mine have been up there for 13 years with Sharp 175W panels. There are some wind load calcs that you should do to check.

 

[Robkh]

I did my ground mount with 2" galvanized pipe frame + 10ft long universal strut (beefier type) cross-members with bolted hold-downs. Built this array by myself (1 person). Worked well. The array is nearing 4 years... no rust, no problems, no loose hold downs, and steady in winter storms.
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The basic items used are
- U-Bolts to bolt the universal strut to the 2" galvanized pipe
View attachment 161273
- nut w/plastic ring for hands-free fit in the channel + bolt + square hold down like this demo pic
View attachment 161267


Here's an edge view showing the bolt hold-down into the universal strut mounting numbers. The panel edges sit on the edge of the universal strut. When you have side-by-side panels, 1 x hold-down works great.
View attachment 161269

For the end panels where there's only 1 edge and the square hold-down doesn't have 2 panels to hold 'flat', I used a strut near the edge but completely under the panels. Used a piece of semi flattened EMT conduit to provide a base for the square hold-down to lay flat and not tilt off the edge of the panel.
View attachment 161271View attachment 161272

Great use of pipe. Question what did you buy to connect the transverse 2” pipe to the vertical pipe - looks like you mounted something on the top of the steel pipe and connected two U bolts. Home Depot?

 

[OffGridInTheCity]

Great use of pipe. Question what did you buy to connect the transverse 2” pipe to the vertical pipe - looks like you mounted something on the top of the steel pipe and connected two U bolts. Home Depot?

I used IronRidge Top Caps - https://realgoods.com/ironridge-ground-mount-system-top-cap - which are made for this purpose.
They have options for 2" and 3" vertical pipe. Not pushing the specific link/company above - just the 1st one that popped up for google search.


I used the 2" version because my verticals are 2" x 10ft (threaded) galvanized pipe from Home Depot - https://www.homedepot.com/p/Southland-2-in-x-10-ft-Galvanized-Steel-Pipe-568-1200HC/100565809

The threading let me extend a little more than 10ft upward in a few cases using a coupler + additional 2" pipe and let me use 2" galvanized flanges to hold the base within the concrete footers - https://www.lowes.com/pd/Mueller-Proline-2-in-dia-Galvanized-Floor-Flange-Fittings/4330338 - so the pole wouldn't slip downward.

 

[glandpuck]

Options for connecting panels to strut are in two basic classes. So it really depends on situation.
1. code compliant solutions for weather loading and wind This would include individually engineered/stamped and or factory documented/engineered systems.
2. non compliant solutions

Make sure you use the proper strut material if outdoors or in a wet location.

They are approved by code for use in California.