framing panels

I'm putting solar panels on my 4 degree north sloping. E-W aligned box section garage roof. So in order to angle them appropriately, I need to put them on tilted frames. Think of it like a ground mount frame that has to be tilted, but attached ot a metal/timber roof so being light is important. We get storms here occasionally in winter, but infrequently and site is reasonably protected - but it needs to keep the panels in place in case of a blow!

So currently I have this shape section which can be joined to make long rails, and clamps that bolt into the rails with square nuts to hold the solar panel frame in place




The panels will be in landscape orientation, with two rails per panel running near the top and bottom. At the bottom, hinges connect the frame to the roof and rafters. At the top, an adjustable strut connects to the rail, with its base screwed into the roof/rafters. So far so good.

However, when testing this, there is nothing vertical running from the hinge at the bottom to the top of the panel - the solar panel frame provides the relevant stiffness. It's decidedly bendy when I lift it by one corner, as you might imagine - but does this matter?

Should I have some other bracing between the rails, or is the panel enough? remember these are tilted up from the horizontal by about 35 degrees.

i.e. if the panels are the blue below, the red lines are the framing I have - do I need the yellow parts? (If this were lying on the roof, the bottom red rail would be on hinges into the roof, and the top would be lifted up away from the roof on longer struts.)


And if I do need the yellows, what's the best way to achieve this? more of the same framing (but I can't find a particular attachment device to join them - do I just both them together?), or use box section alu for these parts and bolt?

I suspect that when the struts are on the back and all is tightened up it'll be quite rigid, but interested to hear what others think.

What about putting the hinges on the yellows and putting the red rails on top? Mostly because it seems easier to mount and because then it won't matter if the yellows are under the reds.

What sort of adjustable strut?

I would guess that you would want it to be really stout as that is a fairly large surface to catch wind.

You could also just mount them vertically on the south facing wall of the building if that is possible. Might be a lot easier.

MTM98290 said:

What about putting the hinges on the yellows and putting the red rails on top? Mostly because it seems easier to mount and because then it won't matter if the yellows are under the reds.

What sort of adjustable strut?

I would guess that you would want it to be really stout as that is a fairly large surface to catch wind.

You could also just mount them vertically on the south facing wall of the building if that is possible. Might be a lot easier.

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Has to be garage roof. Diagram is slightly misleading as noted above - the yellows will be below the reds if they exist. Will also be between the panels if they appear.

Mounting hinges and struts to the rail is simple as they have appropriate fastenings..

Struts. Decently made and good strength.

Panels are edge on to prevailing wind, and sheltered from wind blowing across them (so less lift issues).

Thinking more, I think the yellows are superflous -they resist extension and compression forces, and there are few of those. They might help if the panels were subject to a lot of pressure across the middle of the panel but we don't get dumps of snow that might cause that, and I can't really see them resonating with such amplitude that it's a problem (or that the yellows would come into play).

Put it another way - for those with ground panels, have you propped them near the top and not supported them down to the base? E.g. top resting on a large log, base on the ground?

I built all my PV on tilting frames.
I make a full frame that supports all four edges of every PV panel, with the pivots and supports first, then install the PV on top.
ie I don't use the PV's frames as part of the structure or rely upon it.
However unlike your situation 'tons of snow' is a 'highly likely' part of my loading reality.

update - decided to build it without the alu struts and see how strong it is, and take it from there....

Beware UK planning rules especially if it will be visible from a road or you have neighbor problems. Quote :

Development not permitted

A.1. Development is not permitted by Class A, in the case of solar PV or solar thermal equipment installed on an existing wall or roof of a dwellinghouse or a building within its curtilage if—

(a)the solar PV or solar thermal equipment would protrude more than 200 millimetres beyond the plane of the wall or the roof slope when measured from the perpendicular with the external surface of the wall or roof slope;

yes it's all within the roof (and garage not visible to beighhbrouts or from road). Roof (to be done next) visible to neighbours but will be inside roof limits.

xcentric said:

Struts. Decently made and good strength.

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can you share the source please = interested.

ebay
e.g. https://www.ebay.co.uk/itm/354848419744?var=624158056291

Update - put two panels on the frames (there will be 5 in total) - and it's pretty stiff and supported well. Adding another strut or so, so that there's one per panel, but the trial fit out means I've cancelled my order for the bracing aluminium struts.

xcentric said:

yes it's all within the roof (and garage not visible to beighhbrouts or from road). Roof (to be done next) visible to neighbours but will be inside roof limits.

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I don't think you are reading it right, it means no part of the installation can protrude more than 200mm from the roof covering (tiles or whatever) so that pretty much rules out tilting of any kind. Of course it may be out of sight out of mind but don't forget to allow for wind lift that can be considerable for panels projecting to far from the roof.

Ah I see what you mean. I think you're right - but it's not visible so I'll just gently move along and address it if it ever comes up. I'd simply adjust the garage roof to become gently M shaped, I guess.

I probably need a picture to understand this, but if you're saying what I'm thinking then I feel like the panel to rail attachment plus the rigidity of the panel will not allow the rail to roof connection to suffer a twisting force.

That's if we're doing intuitive engineering here. If you want factually engineered then have to refer to the engineered system's instructions.

Pictures. rails not separated by other bracing, but having put 2 (of the 5) on it's pretty rigid because of the framing of the solar panel. Yes I know the rail isn't straight at the front - that part's not fully attached yet.

As a side note, I may move the whole array back 1.5m which means it'll hardly be visible above the front of the roof.

xcentric said:

As a side note, I may move the whole array back 1.5m which means it'll hardly be visible above the front of the roof.

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High quality engineering mockup here - angle ladder supporting spare roofing panel that is standing in for a solar panel. So ignore the end of the ladder and red bits - this is how the panels will look moved back 1m from the edge, from the house (which is the furthest away from the garage) - so mostly not visible. I'm going to go with that. Now, back outside to remove all that from roof before the gales blow it off.....