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Flexpanels (CIGS) instead of Glass Solar-Panels?

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Hi,

I want to put some Solar-Panels on the Roof of my Fiat Ducato. Because the weight really matters to me (need to stay under 3,5t), I'm thinking about using flexible Panels. Because Will strongly recommends the CIGS Modells I would use these.
It seems like they are only available on China Shops right now. (for Europe)
What do you think about these CIGS Flex-Panels? Have anyone already one of these? They are available in sizes up to 560w but for me the 90w would fit best. With 1-1,5€/W they are also not too expensive.

But because it's mounted directly on the surface of the roof, it's getting much hotter and because of that the efficiency will drop much more compared to the Glass Panels with an Air-Gap between, right? Also I guess it's getting hotter inside the Van because of that?!
But I saw a Tutorial about putting "Twin-wall sheets" between the Panel and the roof for some airflow. How much of the heat Problem is getting solved with this mounting method?
Another big down point is the efficiency/size. Only 3x90W is fitting on my roof, with overlapping Glas-Panels it would be 3x 150W. But I think 270w is enough for us.

Thanks a lot and sry for my bad English

Dominic
 
I used flexible panels like that on my Van - and all of them died after 2-4 years. Hope they are better these days.

You could do 2x 150w.

You can safe more weight with other measures. Build your furniture not with solid wood. Use some aluminum.

I got a Chevy Express, which is a lot heavier empty then the ducato, completely build at 3100kg.
 
And they are also CIGS?
That's really disappointing but thanks a lot for the warning!


No, it doesn't fit. I had 3 "windows" on the roof.

Yep CIGS.

I got non-flexible CIGS on my house - they are still working perfect after 10+ years.

You have to think - that the whole metal chassis of the van is moving all the time. At a different rate then the panels.
A Van is fairly flexible. So basically - the roof is bending the panels - every day.

The nice thing is the CIGS panels are not failing from one day to the other - they are degrading with more cracks appearing -
So you get some notice.
 
Going just slightly off-topic from CIGS, because I personally recommend something else.

Semi-flexible CIGS panels are thin-film, and prone to microscopic cracks. Maybe a bit less failure prone than old-style "semi-flexible" silicone-celled panels. I have no personal experience with CIGS panels. But I have a lot of experience with silicone-celled panels on Trailer and Class-B RVs. The average lifespan is only about 5 years in heavy use, and depends primarily on weather exposure and flexibility of the mounting substrate. Proper mounting also critical, to avoid creating cracks from both vibration and heat-cold expansion/contraction of the underlying mounting surface. Failures can occur both within cells and wiring at the top surface, AND within wiring at the bottom surface of the cells. Failure in the bottom side wiring of panels nearly always kills the entire panel, without any warning (exactly As eXodus described above.)

So with any "flex panel", but especially with panels based on silicone cells - it is critical to allow for expansion, contraction, and twisting of the mounting substrate. (Most of my installations have been on aluminum RV roofs. Some have been on thin steel-roofed conversion vans.)

I have switched all of my more recent installations, to use the newer design "shingled" semi-flexible panels exclusively. The top surface protecting layer is much thicker - variable in thickness, between peaks and valleys of the underlying shingled cell edges. But overall, they are MUCH stronger and more durable, MUCH less likely to allow cracking along the top surfaces of underlying cells. Even with abuse - one of my customers was scraping snow off from her panels after a snowstorm at Snowmass, a couple of months ago. No subsequent performance issues or visible damage have occurred with that Van.

So I like using these, and mounting to the motion and expansion-prone surface via VHB tape strips: https://www.ebay.com/itm/2-100W-Fle...or-Camping-RV-Caravan-Van-Marine/283716192472. These are in USA, but there may also be European Solar Distributors who stock them.
 
Reading this thread has given me some ideas, but some questions, too- I have a small TT that I eventually would like to mount solar to, but I want it to be really low profile (it's a low trailer so that it can go into my garage...).

The roof isn't flat- it's more like a truck bed with shallower bumps made from galvanized steel. And it's not really flat thanks to years of life (it turns 50 this year).

SO, for this thread- in theory, I could mount flexible sheets to a very thin sheet of something over my roof. If one was going to mount flexible panels onto a sheet of *something*- what something would that be to match the expansion rate of the panel?
 
Reading this thread has given me some ideas, but some questions, too- I have a small TT that I eventually would like to mount solar to, but I want it to be really low profile (it's a low trailer so that it can go into my garage...).

The roof isn't flat- it's more like a truck bed with shallower bumps made from galvanized steel. And it's not really flat thanks to years of life (it turns 50 this year).

SO, for this thread- in theory, I could mount flexible sheets to a very thin sheet of something over my roof. If one was going to mount flexible panels onto a sheet of *something*- what something would that be to match the expansion rate of the panel?
alfraec: My own Trailer, and most most my TT installs, have been on garage-stowable fold-up Trailmanors. The upper front and rear "shells" are made of an aluminum sandwich of thin sheets, separated by foam insulation. In raising and lower the roof shells, there is A LOT of flex. They are spring-loaded.

If your bumps are either flat-topped (like a truck bed) or slightly rounded, then you can attach directly. I am frequently leaving loose space underneath vinyl-covered seams in those Trailmanor roofs, with no issues. My normal scheme for RVs is to attach those shingled flex panels with only 1" wide strips of VHB tape, about RP25 thickness, to handle different coefficients of expansion between the roof and Solar panels. (The Trailmanor roof shells get quite hot in summertime camping, and so does your galvanized roof. Steel roofs on Class-B RVs expand at the same rate as your Trailer, and I've done several of those in the same way.)

I think that hassles of adding a second "backsheet" would create no advantages in lifepsan, while adding costs and an additional layer of attachment. The "semi-flexible" shingled panels are thicker and less flexible than CIGS, they can actually go over mounting gaps between your bumps with free air underndeath - as long as you don't walk on them.

Align your panels to fit lengthwise along the bumps, with each edge of the panel preferably sitting solid on a bump (rather than hanging in air, although a tiny bit of overhang is OK). Along the closer-to-center panel long edge, apply VHB tape in strips which are each about 6 inches long, with roughly 1-1/2 in gaps between strips. Along the short edges of the panels, use 3 pieces - a bit longer for the middle piece and again two gaps between the 3 pieces. As you begin to press into your roof, from the closer-to-trailer-roof-centerline panel long edge, add just 3-4 additional strips to the underside of the panel, separated by much wider spacing, along the "bump" nearest the middle of the panel.

If your bumps are uneven, or if they are rounded (rather than flat on top), then both thicker VHB tape (RP32, or even thicker) to allow for a bit more stretching onto the non-flat surface, while the tape on the panel side remains totally flat.

This mounting scheme is leaving intentional gaps between segments, allowing rain to get driven underneath the panel on purpose. (Rain get driven into the gaps, especially during high speed travel, but drains out through other gaps. Water vapor also escapes when the panel and roof warm up in sunshine.
 
Thanks. That gives me a lot to think about.

The bumps are flat, like a truck- but oriented across the trailer instead of along it (like a truck). If I put the panels right on the bumps, that would mean that I have to very much make sure the roof paint/sealant is adhered really, really well.
 
Reading this thread has given me some ideas, but some questions, too- I have a small TT that I eventually would like to mount solar to, but I want it to be really low profile (it's a low trailer so that it can go into my garage...).

The roof isn't flat- it's more like a truck bed with shallower bumps made from galvanized steel. And it's not really flat thanks to years of life (it turns 50 this year).

SO, for this thread- in theory, I could mount flexible sheets to a very thin sheet of something over my roof. If one was going to mount flexible panels onto a sheet of *something*- what something would that be to match the expansion rate of the panel?
Technology progresses.

I bought my flex-panels in 2016 - maybe todays ones are better. Just wanted to share my experience.
I had 2x 100w flex panels in my van - the first one failed from one day to another after 2 years - I replaced it with another CGIS panel.
So the other panel lost power in like steps - from over almost 150w in full sun - down to like 30 watt in year 4.

I had them glued (VHB) to the roof (as recommended back then) - was a major pain to get them off - including repainting the roof.

Now I got 2x 100w regular framed panels on there. producing more power in most conditions.
 
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