Load check/calc of solar rack for 30° angle on flat roof

Hello,

with my first 2x solar panels (each 395W), I purchase a standard mounting rack.

2x ground panel with profile to mount the triangles on grass roof
2x triangle element (3x each L bracket aluminum 40/40 & 3mm thick connected with M8 srews)
Panel itself will be mounted vertical on parallel PV-alu-profils 40x40 fixed with M10 screws on the triangles..

As we have strong winds & flat roof, I would like to get your experience on if the 2 triangle with 4mm material are strong enough.

Idea is to make in total 4 triangles & make cross connections on rear with 25x2mm aluminum strips for side support of each two.
40x4mm alu is support 2500kg pull force at least follow the math...not considering both L sides.

For keeping it on the roof - I calcuated with 133kg per square meter panel. So 450kg stones to load on base for both panels.

Looking for you remarks & thanks in advance!

Hello,

This sounds like a structural engineering question probably best asked to a structural engineer. However, I'm very curious. Are you asking if 450kg rocks/stones/boulders will hold down your mounting apparatus in the case of string winds?

Yes for both points maybe here is also an engineer around with some experience regarding the structural strengths required and secondly on application of abouve mentioned ratio - if used also in reality.
Setting up only two paneI I think is very frequent in current times and so I assume there should be a lot of experience...

133kg/m^2 was referencing in docs of other supplier, but not sure if this not too much...

The question will probably not be if the mounting apparatus can hold the weight of the panels, but if the whole unit will move around or fly off when a straight lined wind gets under you panels. Also, you'll probably need to know the loading tolerances of your roof. You mentioned having grass on your roof, so presumably it is reinforced to safely maintain the added weight, but now you're trying to put a lot more weight on it. Certainly a structural engineer is a must. I'm sure there would be codes governing this kind of thing.

Al D said:

The question will probably not be if the mounting apparatus can hold the weight of the panels, but if the whole unit will move around or fly off when a straight lined wind gets under you panels. Also, you'll probably need to know the loading tolerances of your roof. You mentioned having grass on your roof, so presumably it is reinforced to safely maintain the added weight, but now you're trying to put a lot more weight on it. Certainly a structural engineer is a must. I'm sure there would be codes governing this kind of thing.

Click to expand...

yes sure focusing on lifting forces by wind & pushing by snow.
Roof weigth limited are no issue here with 500kg for the 3m^2 surface...

You'll need to know the buckling rating of the vertical support. That's determined by material type, shape, and attachment geometry. I'm not that kind of engineer so my experience is subpar to a professional, which I would want to consult before doing this project. But that's just me.

I hope you get your answer from somebody more knowledgeable.

What about wind diffuses for the panels to help alleviate lifting? Have you researched actual production with the panels in a flat, or almost flat orientation, vs the desired 30* tilt? IIRC, some posters here have found little difference in tilt angles, but we do not know your location. YMMV.

Mini_PV said:

As we have strong winds & flat roof, I would like to get your experience on if the 2 triangle with 4mm material are strong enough.

Idea is to make in total 4 triangles & make cross connections on rear with 25x2mm aluminum strips for side support of each two.
40x4mm alu is support 2500kg pull force at least follow the math...not considering both L sides.

For keeping it on the roof - I calcuated with 133kg per square meter panel. So 450kg stones to load on base for both panels.

Click to expand...

What direction is the strongest wind coming from?


Where are you located?

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