how to fix panels to a unistrut support frame

[riccol1966]

ok, this is probably a silly question but it baffles me. I have 3x100 watt monocrystalline panels to install on my pitched roof (concrete tile), and I am planning to push up the tiles, install some roof hooks and then use unistrut connected to roof hooks to create my panel frame. Now, with the unistrut in place, all I have to do is bolt the panels on. But, heres the thing - all pv panels come with rear fixing holes. So when you lay the panel flat on the frame, how do you get access behind the panel to fix the screws, because the roof is in the way! 

Has anyone actually put panels up using a frame, and if so how exactly do you go about it?

Thanks.
 

[Ivan]

Why not drill some holes in the sides of the panel frames - that's how the panels are fixed onto the frames in this picture (frames are from the solar water panels):

www.c-zero.co.uk

[riccol1966]

Thanks, yes I have some panels I got a year ago and thats what I did, but was wondering how the 'professionals' actually get them connected from underneath, because I want to mount the panels flush with each other. Its really annoying seeing all these panels in big arrays everywhere and I just cannot figure out how they do it.... of course if I saw them being installed then all would become clear....

 

[Ivan]

I think they normally clamp the panels with long bolts screwed against a retainer plate flush above the panels.

[Mike N.]

You could stand the frame off the roof with spacers of sufficient length to allow you to get your arm underneath and work your way along row by row  if your arms aren't long enough for a big array.

Mike

[Paulh_Boats]

Where can I buy a roof mounting frame for my 2 Unisolar 64Watt panels?

This pic taken at 9am today, shows the easiest place to install them to catch the winter sun:



I have several lengths of aluminium angle, but there must be a ready made solution??

cheers
Paul

[Ivan]

the ready-made 'professional' solution will cost almost as much as the panels, unfortunately. I'd recommed using some roof mounting straps and your angle...

[KenB]

Paul,

I would have placed them higher up, and possibly one each side of the solar water heater,  on the same baseline.

You could probably then arrange for your support frame to be bolted to the existing frame and share some common mountings- bringing the cables from each panel through the roof at the ends of the tube manifold - sharing the same holes.

The additional weight of the panels should not be a problem if you have some mounting fixtures at each side.

Call me artistic/aesthetic, but I think that anyone looking at your roof from behind would ask the same question.

It's a shame you've painted that big red box on the roof already   




Ken

[wyleu]

How high does the shadow of the trees get? If they shade any part of the PV panels they will significantly reduce the output.

[Paulh_Boats]

Thanks for the replies,

1) The trees are just above the eaves, southeast from the house so even in winter after about 9am the roof gets clear sun.

2) Shame about the red line Ken, I could add some flashing xmas lights to conceal it. 

3) I want to keep it artistically balanced for sure. But I plan to add more panels in the future so its going to be a juggling act.

There is a threaded rod drilled through the roof (bottom right) to support the existing panel. I can attach to that and also loop the PV frame over the gable end and bolt it to the wall.

Its hard mounting the scaffold tower over the conservatory, so I chose the right side for an easy install.

Any chance of getting hold of your stainless frames Ivan??

-Paul

[Ivan]

Problem is that you need the two side rails and bottom rail from the panel, so we'd end up with a useless panel. The A-frame/flat roof kit would be a good option, but it doesn't have these bits. The stainless sections provided aren't very useful for this job (I've considered it previously), and they are buggers to drill. I got through 3 or 4 brand new drill bits (including carbide ones!) in drilling my holes.


Ivan

[Paulh_Boats]

Thanks Ivan, I see your point about a useless panel.

I'll keep looking, there must be a source of stainless L or U section out there somewhere....

cheers
Paul

[martin]

use 2 lengths of L section ally!
(which will give you your U shape, and is light, and easy to drill!)
like this-


then all you need is an attachment to the roof - marry up the "blades", and bolt top and bottom!
 - a bit like this

[Ivan]

Of course the other benefit of mounting them as Martin has shown, is that the panel has decent air space behind to help cool it (solar PVs are less efficient when the temperature increases - hence 4" recommended clearance from the back of the panel)

Ivan

[wyleu]

if that's softwood it should probably be treated with something noxious to stop it falling apart.