flexible PV mounting on corrugated aluminium roofing sheet

[tanuki.himself]

How feasible would it be to mount flexible solar panels onto something like a corrugated/trapezoidal section aluminium roofing sheet to make a lightweight panel that can then be mounted like a rigid panel with an air gap below? it would mean that there would be some parts of the PV panel unsupported for I guess a couple of inches. at each corrugation. Would this lead to the panel sagging/cracking/failing?

I'm at the stage of my build where I need to chose panels for mounting on my camper flat roof. I don't like the idea of fixing flexible panels directly to the roof because of heat transfer, but i'm balking at the weight of rigid panels. Looking around for something cheap and lightweight to use as a substrate that is rigid enough take the weight with sagging, and that can conduct the heat away from the back of the panel rather than insulating it....

 

[hour]

I'd consider the fact that the very nature of flexible panels will lead to cracking and failing. And how you'd go about feeling confident with a flexible panel mounted to an uneven surface held down only by the 4 or whatever grommets the panel has. I don't know that I'd mount flexibles with an air gap... I see the panel moving quite a bit at speeds. I think they're meant to be stuck flat to a surface, even if that prohibits air flow.

 

[dreadlocks]

I had an uneven surface on the top of my lil car camping trailer I tried to strap a flexible panel onto.. it was foobar within 2 years, whole thing fell apart like the cheap piece of crap it was..

Rigid or save your damn money.

 

[FJR Colorado]

Rigid panels are very light. Is your roof just aluminum skin?

 

[tanuki.himself]

Rigid panels are very light. Is your roof just aluminum skin?

rigid panels will add about 50kg to the camper weight, flexibles by themselves would add about 16kg, so even with a substrate skin i could probably save 25kg for use elsewhere. Roof is 34mm fibreglass/styrofoam sandwich - it can take the load, but i am going to be close to the trucks GVM when fully loaded anyway, so looking to save weight where i can. I also want to keep the panels removable if I change vehicles in future

I'm thinking of this kind of substrate but the other way up, so 80% of the panel would be supported, and the panel could be glued to the substrate where it is in contact and not just fixed in a few points. I guess i could even fill in those gaps with something like expanding PU foam so provide more support and help glue the PV down as that stuff sticks to anything....but then it would act as a heat insulation in those areas

 

[Alloy]

Aluminum will get really hot in the sun...not good for solar panels.

 

[FJR Colorado]

rigid panels will add about 50kg to the camper weight, flexibles by themselves would add about 16kg, so even with a substrate skin i could probably save 25kg for use elsewhere. Roof is 34mm fibreglass/styrofoam sandwich - it can take the load, but i am going to be close to the trucks GVM when fully loaded anyway, so looking to save weight where i can. I also want to keep the panels removable if I change vehicles in future

I'm thinking of this kind of substrate but the other way up, so 80% of the panel would be supported, and the panel could be glued to the substrate where it is in contact and not just fixed in a few points. I guess i could even fill in those gaps with something like expanding PU foam so provide more support and help glue the PV down as that stuff sticks to anything....but then it would act as a heat insulation in those areas

View attachment 588971

As others have mentioned, that roofing would not be a great idea.

A 100W Renogy panel weighs somewhere between 14 - 22 lbs depending upon model. Just what are you planning on mounting up there? Even 400W+ of panels wouldn't equal 50 kilos. And that's with a bunch of 100W panels (which would be silly).

Personally, I would use rigid panels no question. I would not want to drill into that roof. Make yourself a frame of lightweight aluminum square tubing. Mount it to the side as best you can. Think of something like the aluminum ladder racks you see on utility trucks and toppers. Mount Renogy panel(s) to this sub-frame. You can easily re-jigger as needed in the future and have no roof holes.

By the way, don't penetrate the roof with solar cables either. Run them down and back up thru the floor.

See my 2006 Tundra build for ideas (although many of the old pics are now missing).

 

[zoblo]

I have been thinking about using these greenhouse panels from home depot and to attache a flexible panel to, but haven't gotten to it yet. Being corrugated like cardboard there would be some airflow but yet flat and rigid.

 

[dreadlocks]

Rigid panels are worth the weight, speaking of which.. damn how much solar are you putting up there? I've got 650W of solar and its not even close 50kg.. more like 36kg.

Flexible Panels are pure and total trash, DO NOT BUY THEM.. they will fail, and it will be very soon.. if you glue em to your roof that means a new roof in a couple years when they have all delaminated and internally shorted.. heat will accelerate their death if you fix em right to a metal surface..

 

[tanuki.himself]

i was planning on 4 x 175 watt Victron panels which weights in at 12kg each according to the manufacturers data sheet.... and it sounds from opinions here this is still the right thing to do

 

[rayra]

OP, glue flex panels to a metal skin is a stupid idea. The heat will diminish your output and accelerate the death of the panel.

 

[tanuki.himself]

I don't think i am making myself clear here. The point of an aluminium backing panel cut to fit the size of the PV panel is to conduct heat away from the PV panel and into an air gap - it would act as a heat sink. I could easily make a composite backing panel and glue the PV to that to make it removable and lightweight, but that would keep the heat in the rather than helping it to dissipate into the air gap

 

[1000arms]

I don't think i am making myself clear here. The point of an aluminium backing panel cut to fit the size of the PV panel is to conduct heat away from the PV panel and into an air gap - it would act as a heat sink. I could easily make a composite backing panel and glue the PV to that to make it removable and lightweight, but that would keep the heat in the rather than helping it to dissipate into the air gap

Although you are trying to eliminate weight AND keep your solar panels from roasting, I think your idea would lead to easily damaged panels due to the flexible panels fluttering in the breeze. Even with careful bonding of the flexible solar panels to the peaks of the roof panels, wind fluttering would occur. The roof panels would contract and expand with temperature differently than the flexible solar panels, which would stress the flexible solar panels. Falling pine cones, ...

Replacing any damaged solar panels would be slow and tedious.

Mounting flexible solar panels to a "roof shade" aluminum panel with enough of an air gap from aluminum panel to roof would work better than flexible solar panels bonded to corrugated roof panel peaks, but would likely still be susceptible to wind flutter and thermal expansion mentioned above.

 

[tanuki.himself]

Mounting flexible solar panels to a "roof shade" aluminum panel with enough of an air gap from aluminum panel to roof would work better than flexible solar panels bonded to corrugated roof panel peaks, but would likely still be susceptible to wind flutter and thermal expansion mentioned above.

i can't see a way of easily and affordably making a large enough panel of flat aluminium stay rigid enough - it would either need to be too thick to save weight, or any form of batten on the back would have to be bonded in such a way that it doesnt protrude on the smooth surface, and at only 1mm thick to be light enough even countersunk screws wouldnt be reliable. And the battens would dd weight. The roof panels had the attraction that the ribbed design strengthens and stiffens them for very little weight gain...

 

[1000arms]

i can't see a way of easily and affordably making a large enough panel of flat aluminium stay rigid enough - it would either need to be too thick to save weight, or any form of batten on the back would have to be bonded in such a way that it doesnt protrude on the smooth surface, and at only 1mm thick to be light enough even countersunk screws wouldnt be reliable. And the battens would dd weight. The roof panels had the attraction that the ribbed design strengthens and stiffens them for very little weight gain...

... i'm balking at the weight of rigid panels. Looking around for something cheap and lightweight to use as a substrate that is rigid enough take the weight with sagging, and that can conduct the heat away from the back of the panel rather than insulating it....

... I also want to keep the panels removable if I change vehicles in future ...

I think rigid solar panels, despite the slight additional weight, would work the best for you. They would be more reliable, easier to replace if damaged, easier to warranty out if they simply fail, easier to move to another vehicle, and easier to safely clean of snow/mud/bird-droppings/tree-sap/... than difficult-to-mount-and-keep-cool flexible-solar-panels.