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Mounting panels with unistrut

evad

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Feb 21, 2020
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How are the panels attached to the unistrut ? I had planned to make up a fitting using a short piece of 90 angle but there may be other methods.
 

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.

Solar_Panel_Mounts_Z_Bracket_Set_of_4_7-15-2018_1-1_668x668.jpg


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.
RICH_SOLAR_Solar_Panel_Mounting_Hardware_Z_Brackets_RS-ZB4A_1-1_668x668.jpg
 
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.
 
HRTKD. Yes those are the brackets that Renogy has. I fastened to the panels as meant to be. Then the 1/4 machine screws held those brackets to the uni-strut with the lugs I linked above. The alignment of the uni-strut was part of the design.
 
When bottom side of the frame is accessible (not mounted low on a roof) and the rails could be shifted for alignment, I've just put bolts through the mounting holes in panel frames, into the Unistrut or similar slot nuts. That could work, for instance, if using U-bolts to mount Unistrut rails on a pipe frame (as an alternative to solar mount rails also used that way.)

I've put up ULA series racks where the manufacturer sent me drawing and whatnot for the permit office. Also, I've planned arrays that stayed under the structure size for no permit required. (City charged me more for a "permit" not to have a building permit (stamped my plans as such) than they charged for the electrical permit.) Rooftop, if we stay under 40 pounds per attachment point we don't need a mechanical permit. I would want to lag screw into rafters not just sheathing anyway.

It is hard to find hot-dipped galvanized unistrut anymore, most are just a thin coating. Aluminum would be good. Stainless hardware is expensive, but so far I've gotten away with regular steel slot nuts and stainless bolts.

I like the way those Unistrut solar end clamps work, actually clamp to the rail properly with a nut.
 
I'm building a Unistrut DIY rooftop mount for my panels. I too strained and stressed over the different mount solutions, and I found that all engineered rails were expensive and were made with code compliance and inspections in mind. I'm rural, so inspections and permits aren't as big a problem. I saw the pipe-based rails some have mentioned, but I wasn't happy with the panel to pipe interface possibilities and rust(!) was definitely going to be an issue with steel pipe. Wood was out of the question.

The choice came down to Aluminum or Galvanized steel Unistrut. The cheapest I was able to find Al Unistrut was about $70 per 10' for 1-5/8"x1-5/8" slotted strut. With shipping from Grainger it was about $1300 for 15 struts. Galvanized was $450 from Home Depot in my neighborhood and I could take it home right off the shelf in my truck. So galvanized it was.

I chose Quickbolt mini flashing and their lag bolts as the mounting hardware solution. Low cost and minimal install work for my asphalt shingle roof type. I had to find a way to properly tie the quickbolt to the unistrut spacer (simply a cut piece of regular strut 4" long) so I settled for a combination of 1" stainless washers, stainless lockwashers, and the stainless nuts provided by quickbolt. I would then mount the unistrut rail to the unistrut spacer with a stainless spring nut and another lockwasher and washer and stainless bolt. (Pics soon!) I didn't use square washers or the solar panel strut washers Unistrut offers since I couldn't find them in stainless steel.

Piecing together the mounts and hardware was a minor engineering exercise, but I was able to source aluminum panel clamps, 316 Stainless bolts, washers, lockwashers, and also stainless spring nuts on Ebay for less than $250 total. Pics coming soon.
 
I'm building a Unistrut DIY rooftop mount for my panels. I too strained and stressed over the different mount solutions, and I found that all engineered rails were expensive and were made with code compliance and inspections in mind. I'm rural, so inspections and permits aren't as big a problem. I saw the pipe-based rails some have mentioned, but I wasn't happy with the panel to pipe interface possibilities and rust(!) was definitely going to be an issue with steel pipe. Wood was out of the question.

The choice came down to Aluminum or Galvanized steel Unistrut. The cheapest I was able to find Al Unistrut was about $70 per 10' for 1-5/8"x1-5/8" slotted strut. With shipping from Grainger it was about $1300 for 15 struts. Galvanized was $450 from Home Depot in my neighborhood and I could take it home right off the shelf in my truck. So galvanized it was.

I chose Quickbolt mini flashing and their lag bolts as the mounting hardware solution. Low cost and minimal install work for my asphalt shingle roof type. I had to find a way to properly tie the quickbolt to the unistrut spacer (simply a cut piece of regular strut 4" long) so I settled for a combination of 1" stainless washers, stainless lockwashers, and the stainless nuts provided by quickbolt. I would then mount the unistrut rail to the unistrut spacer with a stainless spring nut and another lockwasher and washer and stainless bolt. (Pics soon!) I didn't use square washers or the solar panel strut washers Unistrut offers since I couldn't find them in stainless steel.

Piecing together the mounts and hardware was a minor engineering exercise, but I was able to source aluminum panel clamps, 316 Stainless bolts, washers, lockwashers, and also stainless spring nuts on Ebay for less than $250 total. Pics coming soon.
Nice! Send some pics when you can! Thx
 
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.
1691273081571.png1691272046010.png

The basic items used are
- U-Bolts to bolt the universal strut to the 2" galvanized pipe
1691272783649.png
- nut w/plastic ring for hands-free fit in the channel + bolt + square hold down like this demo pic
1691272128453.png


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.
1691272277901.png

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.
1691272409307.png1691272446046.png
 
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Thanks for uploading! Did you use separate grounding connections since the clamps don't have penetrating teeth?
 
Thanks for uploading! Did you use separate grounding connections since the clamps don't have penetrating teeth?
I used something like this - https://www.amazon.com/ISPINNER-Aluminum-Conductor-Connector-Grounding/dp/B09CFYL2MR/ref=sr_1_13 Used self-tappers to screw into the panel frame + array framework and threaded a 6awg twisted copper wire thru them to connect all the panels.

Also used self-tappers to screw thru the universal strut into the 2" galvanized pipe to 'bond' the universal strut pieces to the 2" pipe - so the whole metal structure had an electrical path and the ground wire was attached to it as well as the panels.
 
How are the panels attached to the unistrut ? I had planned to make up a fitting using a short piece of 90 angle but there may be other methods.
I have 18.5 kW of panels mounted on unistrut (Superstrut) using 1/4-20 bolts, nuts and fender washers. It’s a pole mount arrangement so back access is easy. Panels directly against the top of strut, fender washer and nylok nut inside the channel, fender washers that fit inside the channel and are large enough to cover the hole are easy to find. The trick is to space the struts such that the holes in the panels line up with holes in struts. Lay it out on the ground before you attach the strut to your horizontal pipes so you understand the spacing. I’ve had no trouble with REC, Canadian Solar and Solarever 120 cell half cut panels and some off brand 100 watt panels.
 
square hold down
I finally found some square washers on Amazon, but they seem really expensive...from $1-3 each, like this: Square washers

And nothing when I search for Square Hold Downs. This includes searching Tractor Supply and Home Depot. I did buy Nylon Unistrut nuts 3/8" at Home depot, $7 per 5 nuts...plus bolts and washers (small ones).

I did find a few other considerations on Amazon: Clamps with strut nuts But seller has a caution, and long shipping time. I found a few other options, but would require even more hardware/modification.

  • Are there any other sources I can shop to find hardware to mount 35mm panels to unistuts?
  • Should I spread the panels out a bit? It would be better for shade in the morning to not have space...and move the panels all the way to the west of the 30' area of the barn...would leave 5' on the east side. 6x 48" wide panels.

Thanks for any feedback!
 

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I finally found some square washers on Amazon, but they seem really expensive...from $1-3 each, like this: Square washers
I am using aluminum strut and the channel for the strut, this 30 mm square washer could slip through or perhaps just barely overlap the gap.

I have 1” fender washers that will easily slide through the gap. I bought 2” wide by 1/8” aluminum bar and am cutting that in pieces to keep my mounts from slipping into the strut channel. I’m cutting this to 2” x 3” rectangles and drilling holes for bolts to slide through.
 
I did find a few other considerations on Amazon: Clamps with strut nuts But seller has a caution, and long shipping time. I found a few other options, but would require even more hardware/modification.
This looks like it will work, but on that link and others I browsed when sourcing parts, I did not see dimensions or the words made for strut so I can’t say for sure. This stopped me from getting those
 
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