Question s regarding mounting panels on a curved roof?

[PNW_Steve]

This has been fun and interesting but I am still looking for thoughts on the mounting method shown in the picture?

Thanks

S.

[J.P.M.]

This has been fun and interesting but I am still looking for thoughts on the mounting method shown in the picture?

Thanks

S.

FWIW, if vehicle and/or road vibration were not a consideration, I'd use standard residential rails attached to the panels, but to be safe, I'd pay attention to the rail to panel clips/attachment method, as standard type clips, etc. may not be designed for the cyclic vibration and stress they might likely encounter in this application.

As for the attachment to the vehicle roof in the photo, it's hard, for me at least, to comment on the method shown in the photo. Bolting as appears to be used per photo may be a sufficient method as long as sealing against moisture ingress can be adequately addressed, but the quantity, size, spacing and sealing/gasketing of such bolting makes it impossible for me to comment on the adequacy of the design. It looks nice, but without knowing what the design conditions are that need to be met, from engineering design and safety standpoints, its adequacy cannot be known or estimated.

[PNW_Steve]

Thanks all for your participation.

Looks like I am going to have to "wing it".

I think that I will try the method that I asked about and supliment it with some "L" brackets on the ends of the panels.

[Ampster]

I posted some where on this thread about some $10 brackets (set of 4) but it must have got deleted. I did a google search and some Amazon parts came up. I have actually seen them on flat roofed RVs.

[littleharbor]

Thanks all for your participation.

Looks like I am going to have to "wing it".

I think that I will try the method that I asked about and supliment it with some "L" brackets on the ends of the panels.

Just thought Id mention. I mounted a 120 watt panel on the downward sloped roof on my 5th wheel. Worst place as far as wind coming over the roof of my truck is concerned. I used 4 , 2 1/2" x 2 1/2" angle brackets and self tapping screws. One thing I did was clean the surface of the roof at the mounting points then used 3M 5200 sealant/adhesive under the bracket. Very minimal attachment plan. Well even at 75 MPH on Arizona highways and many years of travel the panel is as solid as the day I mounted it. I'm not recommending using such minimal attachment methods but what I am saying is that you really don't need to overengineer this mounting plan if the wind while traveling is your main criteria.

As I mentioned a few posts back I would build an air foil at the leading edge.

[SunEagle]

This has been fun and interesting but I am still looking for thoughts on the mounting method shown in the picture?

Thanks

S.

Sorry about all of the off topic posts.

That picture would suggest you can mount a number of panels if you have the linear space to run them.

What I can't tell you is what type of bolts or lugs you should use for those channels. It would depend on the roof material and structure (if any) that makes the roof rigid.

[PNW_Steve]

Sorry about all of the off topic posts.

That picture would suggest you can mount a number of panels if you have the linear space to run them.

What I can't tell you is what type of bolts or lugs you should use for those channels. It would depend on the roof material and structure (if any) that makes the roof rigid.

I have the space.

I am confident in my ability to attach the Unistrut to the roof securely.

The roof consists of steel frame members about 24" O.C. covered with 15 gauge steel that is riveted to each frame member.

My biggest concern is that I support the panels adequately.

An option that I am contemplating is to follow the example in the picture and add 2 "L" brackets at each end of the panels.

[PNW_Steve]

Here are a couple of pics of the rig that I am mounting them on:

[PNW_Steve]

I posted some where on this thread about some $10 brackets (set of 4) but it must have got deleted. I did a google search and some Amazon parts came up. I have actually seen them on flat roofed RVs.

Thank you.

All of the factory made brackets that I have found so far are too short to mount to the ends of the panels. If I use something like that I will probably have to make them myself.

I am contemplating "L" brackets made from 1/8"x1" steel.

[J.P.M.]

I have the space.

I am confident in my ability to attach the Unistrut to the roof securely.

The roof consists of steel frame members about 24" O.C. covered with 15 gauge steel that is riveted to each frame member.

My biggest concern is that I support the panels adequately.

An option that I am contemplating is to follow the example in the picture and add 2 "L" brackets at each end of the panels.

If you are not doing so already, I'd respectfully suggest you consider bolting through to the 24" O.C. framing and not simply the sheet metal.

I once had a newly minted and young BSME engineer that reported to me design a pressure vessel lug for a 9,000 lbm lift. The lug was fine and calc'ed out OK, as did the attachment welds, but it was welded to 3/16 " thick vessel wall that would have failed with that loading. It's more than just the lug strength alone.

[PNW_Steve]

If you are not doing so already, I'd respectfully suggest you consider bolting through to the 24" O.C. framing and not simply the sheet metal.

I once had a newly minted and young BSME engineer that reported to me design a pressure vessel lug for a 9,000 lbm lift. The lug was fine and calc'ed out OK, as did the attachment welds, but it was welded to 3/16 " thick vessel wall that would have failed with that loading. It's more than just the lug strength alone.

Thanks for the recommendation.

I had already planned to bolt through the frame members..

My biggest concern is the well being of the panels.

As I ponder this I am considering one run of Unistrut down the centerline of the roof and support each end with two "L" brackets.

[J.P.M.]

Thanks for the recommendation.

I had already planned to bolt through the frame members..

My biggest concern is the well being of the panels.

As I ponder this I am considering one run of Unistrut down the centerline of the roof and support each end with two "L" brackets.

Possibly, but beyond fixation of the frames to resist wind loadings, I'd be more concerned about vibration of the body of the panels (the cells) than the fixation of the frames. I don't have much in the way of solutions here, but the panel faces will have a lot of reason to rattle from vehicle motion/road vibration as well as wing induced flow vibration. Most arrays don't see high winds that often. Chances are yours will see close(r) to wind design loads every time you get on the open highway, and for longer periods more than a usual design consideration.

[PNW_Steve]

Possibly, but beyond fixation of the frames to resist wind loadings, I'd be more concerned about vibration of the body of the panels (the cells) than the fixation of the frames. I don't have much in the way of solutions here, but the panel faces will have a lot of reason to rattle from vehicle motion/road vibration as well as wing induced flow vibration. Most arrays don't see high winds that often. Chances are yours will see close(r) to wind design loads every time you get on the open highway, and for longer periods more than a usual design consideration.

How would you recommend that I deal with this?

Thanks

[SunEagle]

How would you recommend that I deal with this?

Thanks

I would talk to other RV owner's and see what panels they mounted and how they are working out. Since most rigid panels were not really designed for a mobile application I would say vibration could be a factor but there are a lot of them out there mounted to RV's and trucks.

[foo1bar]

I am confident in my ability to attach the Unistrut to the roof securely.

You need to both have sufficient attachment of unistrut to roof - and sufficient attachment of panels to unistrut.
Also I wouldn't be confident in my ability to attach the unistrut to the roof...
Those modules give a LOT of surface area for air to push on.

My biggest concern is that I support the panels adequately.

I know the panels I dealt with had specific instructions on where they expected to be suppported/clamped (at least XX milimeters from the edge and not more than YY milimiters from the edge.)
It had two specificiations - one for traversing the the short dimension of the module (the "width") and another for if you're traversing the long dimension of the module (the "length").

In your case, I'd probably use the built-in bolt holes that the modules have.
For example - here's the instructions with the bolt hole spacing, etc for one brand/model (LG MonoX): https://www.lg.com/us/commercial/doc...ion-Manual.pdf

I don't know how you tell whether a set of 4 M6 bolts is suffiicient to hold down a module like that on a vehicle moving at 65mph+. Especially when you start adding wind from mother nature (and "wind" from passing trucks, etc)