Standing seam metal roof with or without rails

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electrofelon

electrofelon

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Location
Cherry Valley NY, Seattle, WA
Does anyone have experience and an opinion on both options? That is using S5 ridge clamps with rails vs S5 PV ridge PV kits without rails. I have only used rails and have heard some people say the PV kits are a PIA and not worth it. Also if anyone can comment on material cost both ways.
 
It was years ago that I last looked at this. I was thinking about the PV kits for a project or two and decided against them. Don't remember the pricing or my full thought process but I think I thought that any price advatange for the kits wouldn't be worth it. Install with rails was a known quantity labor wise and throwing something new at the guys to save a few bucks on material would backfire. So since I didn't try them I can't speak from personal experience, but if others say the kits are a PITA then I think that confirms what I feared. Also I didn't want orphan parts and maybe I thought the ones on the outside of the array would look ugly.

Rails are nice for wire management. And somewhat more flexible when it comes to final panel placement.
 
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I will second everything JB said and add that, while I have not installed the PV kits, I have installed other systems that did not have nice wire management features, and regretted it every time. Also we just removed and re-installed a rail-less system for a re-roof. We were not the original installer. The crew's opinion of the system they removed was that it was very flimsy. We re-installed with SNR Ultrarail.
 
Okay thanks guys. Good points on The wire management, I hadnt considered that.

One obvious disadvantage of no rails is the panels would have to mount in a landscape orientation (I think. do any panels allow mounting only at the short ends?).

Component cost should be easy to figure:. PV kits seem to run about 9 bucks each, rails seem to be about 2.50 per foot....
 
Some module makers indeed do have specs on clamping on the short sides of their modules but I believe they have wind loading restrictions for them.
 
electrofelon said:
Ok yeah I pulled up a few instruction sheets and the ones I looked at do indeed allow mounting at the short sides.
Click to expand...
It is very common that they either don't allow this mounting method, or significantly reduce the allowable environmental loads on the module.

A panel should be supported like a xylophone bar, so the span and cantilever can both contribute to its strength. Given only 4 points supporting the panel, the ideal spacing for maximum strength between the supports is L/sqrt(2), where L is the panel length. The "green zone" marked in instruction sheets will include this location, and the factory frame holes will be close to this location.
 
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I installed a system with PV kits once. Just once.

No wire management provisions. No way to conveniently get up and down the roof (rails give you a natural ladder). Ultra tight tolerances. And if you whisper aggressively at one it rocks over because of only one set screw in the S-5!

I legit have no idea what the perceived benefits of them are. They remind me of my senior capstone project where a bunch of book smart morons design a product to fix a problem that does not exist by introducing more problems.

Among the worst products I've ever worked with.
 
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BandGap1.1eV said:
I installed a system with PV kits once. Just once.

No wire management provisions. No way to conveniently get up and down the roof (rails give you a natural ladder). Ultra tight tolerances. And if you whisper aggressively at one it rocks over because of only one set screw in the S-5!

I legit have no idea what the perceived benefits of them are. They remind me of my senior capstone project where a bunch of book smart morons design a product to fix a problem that does not exist by introducing more problems.

Among the worst products I've ever worked with.
Click to expand...
Thanks for the comment. Well the benefit would be not having to buy rails which is not an insignificant cost. Note when I said about $2.50 per foot for rails I didn't realize that was the xr-10 and due to snow loading in this area I would probably need the xr1000s which are a lot more. Granted with rails you save having to buy some s5s, but I really don't know the cost each way.
 
Yeah, rail-less mounting....the dream that remains just that for me.

In theory would be awesome.
I look into it every few years, and for all the above reasons I still stay away.

I never liked being forced into landscape panel orientation and the fact that those mounts need to go precisely in the right spot, not much leeway. Stressful.

On our last standing seam roof job we would have been hosed. Even so, the guys were slipping and sliding all over the metal roof. It was only 26 degrees pitch. Had there been NO RAILS, they would have been even more upset and taken MUCH longer! Not to mention safety.
Was surprised that this metal roof had much less traction vs comp.

One add'l point: rails are nice to mount micros or optis to. Although clips exist to mount them to panel frames.
 
Zee said:
Yeah, rail-less mounting....the dream that remains just that for me.

In theory would be awesome.
I look into it every few years, and for all the above reasons I still stay away.

I never liked being forced into landscape panel orientation and the fact that those mounts need to go precisely in the right spot, not much leeway. Stressful.

On our last standing seam roof job we would have been hosed. Even so, the guys were slipping and sliding all over the metal roof. It was only 26 degrees pitch. Had there been NO RAILS, they would have been even more upset and taken MUCH longer! Not to mention safety.
Was surprised that this metal roof had much less traction vs comp.

One add'l point: rails are nice to mount micros or optis to. Although clips exist to mount them to panel frames.
Click to expand...
When I was doing installations on metal roofs we would carry big bottles of Mountain Dew (the soda) up and pour it all over the roof. When it dries it's very tacky and it washes off in the next rain.
 
This is my first post, so I am new to the forum...but not new to the field.... in business since 1980 installing PV systems.

I have done many projects with Standing Seam Roofs. The key element is how the roof itself is fastened to the substrate or roof deck. The loads must be transferred from the array to the building foundation, and how this is done is the key element to how its fastened. We have seen many systems with an upload force reaching values close to the take off of some big airplanes, so these are real issues to contend with. The upload on these connections is great, and if the roof was not installed to allow for this up load force, it may not be able to handle a non rail system. Typical rule of thumb is double the roof pan fasteners to add solar. So if the roof manufacture will allow solar installed (some do not allow attachment of additional equipment) in the first place, what is the recommended fastener spacing? If they say 12" on center, then you would use 6" on center to attach the roof pans to the roof deck. Also if they say a #8 screw, we would use a #10 or 12, based upon our engineers report. I also have been required to use extra long screws to reach roof joists and also to add blocking below the roof deck between joist. On existing roofs we have many times had to add a S-5 to every seam and use rails, so that we had enough connections to as many seams as possible to spread out the load. Even to the extent of extending the rails beyond the array to hit several more roof seams. Our design wind load can be as high as 140MPH, especially if near canyons or along the coast, so again much is dependent on your location, height of structure and surrounding structures or terrain and the design loads you are having to deal with. For sure this is an area for an engineer to do some calculations on the loads and determine a best method forward.

I hope this sheds some light on why we like rails on systems of this type!
 
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great points.
Wouldn't rail-less actually require as many or more mounting points than rail, typically?

We use lots of S-5 mounts.
We should install every standing seam at 16" OC along each rail, but I modify it and stagger the mounts at 32" OC from rail to rail (1,3,5 etc then 2,4,6 etc). I feel that attaches each row of modules to every single seam......... with half the S-5 mounts.

Basically: I use about 2-3 times as many mounts on a standing seam job since the seams are so weak relative to rafters.
 
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