How much of a panel can go unsupported

[elizabethii]

I'm working on engineering my "ground" mount for a rack of Bluesun 460w bifacial panels. Due to the place I'm planning to put the array, at least some of it would need to overhang a different roof. I estimate I'd have at least 25% of the length of the panel unsupported.

I don't think that will be an issue, but I was hoping to get some validation that this shouldn't be an issue. I'm not in a region to have issues with snow, but we do very occasionally get some strong wind gusts (50+)

 

[BartHenry]

it depends on the suports used, but most manufactures say no more than 25% cantilever

 

[fafrd]

I'm working on engineering my "ground" mount for a rack of Bluesun 460w bifacial panels. Due to the place I'm planning to put the array, at least some of it would need to overhang a different roof. I estimate I'd have at least 25% of the length of the panel unsupported.

I don't think that will be an issue, but I was hoping to get some validation that this shouldn't be an issue. I'm not in a region to have issues with snow, but we do very occasionally get some strong wind gusts (50+)

Are you talking about the panel extension out past the support rail or the support rail cantilever out past the last roof mount?

Generally the manufacturer of the panels and the manufacture of the rail mount system each provide a spec for their respective maximum cantilever / extension…

 

[elizabethii]

cantilever I think is an accurate description of what I'm looking to accomplish. I'll double-check the datasheet, but I don't recall seeing a spec for that listed.

 

[fafrd]

cantilever I think is an accurate description of what I'm looking to accomplish. I'll double-check the datasheet, but I don't recall seeing a spec for that listed.

I use IronRidge and they allow a 40% cantilever (of the underlying support span) but I am pretty certain that is out over a continuous roof surface and don’t believe it extends out past the edge of the roof…

Since the maximum support span of my rails is 5 feet, I can cantilever out past the final support by up to 2 feet…

 

[Mike 134]

Your mounting locations are shown and from that you can determine how much is permitted to be "freeair" at the end

 

[fafrd]

Your mounting locations are shown and from that you can determine how much is permitted to be "freeair" at the end

Most panel manufacturers have an installation manual that specifies exactly minimum and maximum distance off center for support, both portrait and landscape. When determining how much of a panel can hang past the end of the rail, I would rely on those specifications and not where mounting holes have been located within the frame.

But our OP seems to be interested in rail cantilever past the last support on the roof, not panel cantilever past the rail…

 

[Supervstech]

In snow area, I wouldnt hang a panel unsupported more than 10% it varies top vs side vs bottom overhang, but snow is crushing heavy

 

[fafrd]

In snow area, I wouldnt hang a panel unsupported more than 10% it varies top vs side vs bottom overhang, but snow is crushing heavy

Yes, most rail mounting systems include environmental parameters to select the correct specifications for your specific circumstances…

Snow in the Bay Area is a non-issue but the mechanical support should be adjusted to accommodate the demands of any snow in your area…

 

[400bird]

In snow area, I wouldnt hang a panel unsupported more than 10% it varies top vs side vs bottom overhang, but snow is crushing heavy

If you only overhang 10% off the racking, what about the 80% in the middle?
Seems like you'd want a balance between unsupported in the middle and on the edges.

I've looked at a bunch of panel spec sheets recently and haven't seen a single mention of where they want the mounting tails.
My Solaria panels in 2018 had than info on the spec sheet.

 

[Zwy]

I'm working on engineering my "ground" mount for a rack of Bluesun 460w bifacial panels. Due to the place I'm planning to put the array, at least some of it would need to overhang a different roof. I estimate I'd have at least 25% of the length of the panel unsupported.

I don't think that will be an issue, but I was hoping to get some validation that this shouldn't be an issue. I'm not in a region to have issues with snow, but we do very occasionally get some strong wind gusts (50+)

I looked at the mounting holes in the frame and put the rails on the mount at that location except for the end of the mount; I put the Tamarack rail as close to the end of the panel as practical. The reason? Wind gust at the end tend to lift the ends. The datasheet @Mike 134 put up shows the hole locations.

 

[Ptom]

The factory mounting holes in the modules answer the question! Plus or minus a few inches either way (when a home made rack is a bit askew) doesn't seem to matter, and I live in mountain snow country/high winds.