Lapping PV panels to create water shedding roof. Thoughts? Comments?

[crossy]

Think of PVC pipe, cut in half long ways. To form a gutter. Using T's and 4 way fittings to form a grid under all seems. If panels are placed tightly against each other with weather stripping between them. All that you have to catch are the drips that find their way through. So, it wouldn't have to be very large of a pipe/gutter. The hardest part would be fitting it between the panels and support structure.

Actually, it's not going to work well. But, I'll leave it up, to possible inspire other ideas.
Maybe aluminum C channel would be better. So that it can be part of the support system. The seems could be brazed together.

This commercial system from Clenergy https://www.clenergy.com/product/shade/ezshade-2/ uses the guttering idea although the gutters are part of the mounting extrusions.

Let it leak and channel the water away.

 

[ghostimage]

No point of overlapping, as water sometimes travels upwards, trust me. Ether let it leak or put clear pvc roofing or solid sheet metal under it, if you want to water proof. Its not the vertical seams you have to worry about really, its horizontal ones. I mean all of the leak. Ive seen people trying all sorts of "roof in the bucket/tube solutions" before calling us back and putting a conventional roof on. It always leaks. Maybe Tesla shingles is the answer for you.

 

[12VoltInstalls]

failure was nearly guaranteed within 24 months. Your results may vary

I’ve had excellent results on lexel repairs. I used to do a lot of ‘repairs’ for a guy that advertised roof leak repairs and subcontracted all the work.
I had zero callbacks and being a small community I’ve had contact with a majority of recipients and no complaints- and the last repair I did was 12+ years ago.

A surprising number of repairs were already ‘repaired’ with silicone which leaked. Difficult to clean up silicone and get other stuff to stick. And I always tried to flash or use a small piece of roofing or what have you so that lexel or polyurethane wasn’t the only line of defense.

I never attempted repairs on curbed or flat residential roofing- recommended replacement.

90% or more of roofing repairs I did were due to incompetent installation of the roofing itself, or improper skylight, valley, chimney flashing.

 

[Steve Fractals]

I built a lean-to porch, only one row of panels but they are just sitting on and clamped down from underside to my wooden rafters and don't leak where they are sat on the wood without any other seals.

 

[aaroncgi]

Mmm good suggestion. Have you used these, Aaron?

No, I have not used these yet. I do plan to use them (or something highly similar), for a future greenhouse build, but that's a ways down the road.

 

[OffGridForGood]

Polyisobutylene - aka butyl tape, this is what commercial glazers use.

 

[RussNM]

I have to graciously disagree on the butyl tape.. it has been my experience that butyl will dry out, shrink and then crumble after only a few years. Maybe thats only up here where we get LOTS of high altitude sun and really dry weather but we left butyl behind years ago and switched to the polyurethanes. Urethane works so much better but is cost prohibitive. I replaced a rear window in my truck and it took a $60 tube of urethane to do the job. Thats what the auto window guys use.

 

[toms]

I have to graciously disagree on the butyl tape.. it has been my experience that butyl will dry out, shrink and then crumble after only a few years. Maybe thats only up here where we get LOTS of high altitude sun and really dry weather but we left butyl behind years ago and switched to the polyurethanes. Urethane works so much better but is cost prohibitive. I replaced a rear window in my truck and it took a $60 tube of urethane to do the job. Thats what the auto window guys use.

Butyl tape is what you need, the Butyl is covered by a layer of foil. It will last as long as the panels

Lap the horizontal joins (assemble the purlins to keep the panels parallel), and butyl tape the vertical.

In Australia, PV panels can be has for the cost of your time to take them from a demolition site - they make cheap cladding.

 

[JCSchwarb]

I have to graciously disagree on the butyl tape.. it has been my experience that butyl will dry out, shrink and then crumble after only a few years. Maybe thats only up here where we get LOTS of high altitude sun and really dry weather but we left butyl behind years ago and switched to the polyurethanes. Urethane works so much better but is cost prohibitive. I replaced a rear window in my truck and it took a $60 tube of urethane to do the job. Thats what the auto window guys use.

Agreed, butyl will not work as single solution, it will dry out, and particularly not a low slope.

 

[12VoltInstalls]

replaced a rear window in my truck and it took a $60 tube of urethane to do the job. Thats what the auto window guys use

Totally different application.

Polyurethane adhesive caulking is $10/tube

 

[toms]

This is the stuff i have used on to seal roof joins, the oldest stuff i have on the roof has been there for over 15 years, still looks the same as the day it was put there.

We used to use this stuff on the underbody of Holden vehicles as a stick on heatshield between the front pipes / footwell. If the Butyl doesn’t deteriorate when subjected to exhaust temp cycling, the sun isn’t going to get it. UV is the issue causing hardening, and the foil cover takes care of that.

 

[RussNM]

Polyurethane adhesive caulking is $10/tub

For automotive glass urethane is used instead of polyurethane so yes it is different but still a sealer.

 

[12VoltInstalls]

For automotive glass urethane is used instead of polyurethane so yes it is different but still a sealer.

They are both urethane but my point was that the ‘window and door’ products are more affordable than the thick glass mount urethanes

 

[JCSchwarb]

This is the stuff i have used on to seal roof joins, the oldest stuff i have on the roof has been there for over 15 years, still looks the same as the day it was put there.

We used to use this stuff on the underbody of Holden vehicles as a stick on heatshield between the front pipes / footwell. If the Butyl doesn’t deteriorate when subjected to exhaust temp cycling, the sun isn’t going to get it. UV is the issue causing hardening, and the foil cover takes care of that.

The issue I see with this is 1) having to cut it, unless one can find the right width, 2) how to bridge the x and y axis, 3) not sure it will hold in all environments, 4) wide variation in qualities as some rolls hold up well and others don’t. I use this product around windows and doors, but sometimes it has to be stapled to hold. The thin aluminum HVAC tape would likely hold better to aluminum frames, in my experience, but getting the right width may be the hard part.

 

[12VoltInstalls]

Other than using polyurethane between panels and then clamping to rivet or bolt them together I’d probably use this over all these dubious tapes and sealants

 

[curiouscarbon]

Other than using polyurethane between panels and then clamping to rivet or bolt them together I’d probably use this over all these dubious tapes and sealants

 

[Ptom]

I’ve had excellent results on lexel repairs. I used to do a lot of ‘repairs’ for a guy that advertised roof leak repairs and subcontracted all the work.
I had zero callbacks and being a small community I’ve had contact with a majority of recipients and no complaints- and the last repair I did was 12+ years ago.

A surprising number of repairs were already ‘repaired’ with silicone which leaked. Difficult to clean up silicone and get other stuff to stick. And I always tried to flash or use a small piece of roofing or what have you so that lexel or polyurethane wasn’t the only line of defense.

I never attempted repairs on curbed or flat residential roofing- recommended replacement.

90% or more of roofing repairs I did were due to incompetent installation of the roofing itself, or improper skylight, valley, chimney flashing.

Another big fan of Lexel here! Ace Hardware, crystal clear or white, and beside the full size caulk tubes it's available in small squeeze tubes. I first started using it when I needed to seal AND glue my light plane's plexi windshield to the overhead lexan skylight, and that was 15 years ago, still good. It is specifically designed to act as an adhesive to a wide variety of plastics, it is so much more than just a caulk. I have not used silicone for anything since discovering it, it's just better all around.

 

[galstaf]

Polyisobutylene - aka butyl tape, this is what commercial glazers use.

Hey OGFG... Any recommendation of a specific type or brand? Have you used it yourself? Cheers!

 

[galstaf]

Butyl tape is what you need, the Butyl is covered by a layer of foil. It will last as long as the panels

Lap the horizontal joins (assemble the purlins to keep the panels parallel), and butyl tape the vertical.

In Australia, PV panels can be has for the cost of your time to take them from a demolition site - they make cheap cladding.

Haha.. nice.
Yep .. that's what I am hoping for actually. Some super cheap used panels that will come in at a lower cost than plywood (currently 50 dollars plus a sheet)

 

[galstaf]

Totally different application.

Polyurethane adhesive caulking is $10/tube

Suggested brand that you have had success with?