Aluminium mounting structure

stephendv
stephendv Solar Expert Posts: 1,571 ✭✭
in Solar Beginners Corner #1
Hi all,

My sweet Yingli panels have arrived and soon I'll have to mount them on the shed roof. I'm looking for some advise on the dimensions of the aluminium tubing I'm planning on using, as until now, my "calculations" are really just finger in the air kind of stuff.
Attached is a pic of the proposed mount for 3 panels each measuring 1.65m x 0.9m (64inch x 35inch). I plan to mount them vertically and use 2 triangles to support the 3 panels. All the mounting material will be 60mm x 40mm x 2mm (2.3inch x 1.6inch x 0.08inch) plain aluminium tubing. There is no snow and we're not in a high wind area.
It will be installed on a metal roof that already has 15 degrees angle. The mount will be seasonally adjustable between 30 degrees to 15 degrees, so the total angle will be 45 degrees to 30 degrees.

I'm primarily concerned about 2 parts of the structure:
- The 2m of unsupported space between the triangles.
- The compressive strength of the 2 supports at the back of the triangle which will be taking all the force of the wind.
As said above, it will all be constructed from the same tubing.

What do you think?
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Comments

  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #2
    Re: Aluminium mounting structure

    Some closeups of the finished frame. I modified the design in the end. Instead of using a long strut at the bottom, I used a shorter one and moved it further back so that it crosses the back purlins.
    It supports 2 positions at the moment, but moving it is not going to be easy because of the weight of the 3 panels. Probably a 2 man job at least or maybe a 1 man job if I use some sort of jack to slowly lower the structure.

    The galvanized braces on the back joint on there purely for reinforcement because that joint looked a little weak. To be honest I think they're overkill because with the diagonal cross braces (there will be 2 in the final version) there is no lateral movement at all.

    The front strut is bolted to the roof using a galvanized L bracket 3mm. Yes I know I've done a bad thing by mixing galvanised + SS hardware and will eventually replace the galvi with an SS bracket when I have time.
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  • bsolar
    bsolar Solar Expert Posts: 103 ✭✭✭
    #3
    Re: Aluminium mounting structure

    looks pretty extravagent .. personally if i was thinking a fixed mount i would have just plastered the panels down right on the roof, but with that structure why not make another mounting rail at the lower end with an upright member drilled in multiple locations, and with some more of those brackets and some clipped pins the structure could be adjustable .. some simple aluminum angle would work for brackets, might as well get the saw fired up and make it so individual panels can be raised up or down to, i agree your not going to be jacking a ton of panels, you'll wind up with a disaster ..
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #4
    Re: Aluminium mounting structure
    bsolar wrote: »
    looks pretty extravagent .. personally if i was thinking a fixed mount i would have just plastered the panels down right on the roof,

    The roof is only 15 degrees, so I'd lose about 1kWh of production per day in winter which is too much for an off-grid system.
    bsolar wrote: »
    but with that structure why not make another mounting rail at the lower end with an upright member drilled in multiple locations, and with some more of those brackets and some clipped pins the structure could be adjustable
    .. some simple aluminum angle would work for brackets, might as well get the saw fired up and make it so individual panels can be raised up or down to, i agree your not going to be jacking a ton of panels, you'll wind up with a disaster ..

    My concern throughout the design was strength, I don't want to risk thousands of euro's of panel for the sake of saving a few bucks on the mounting structure, so may have overdone it in places. I hadn't considered keeping the vertical members (back part of the triangle) static and then just moving the horizontal ones instead, seems like a very similar solution although it would have saved on alu! Will keep it in mind next time around ;)

    The panels are 20kg each, and there are 3 per structure and since some of their weight will be supported by the front brackets when moving them, the person holding the back part will have to lift much less than 60kg while the back struts are moved. Not too difficult IMO.
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