Tropicool vs VHB - rooftop solar panels

[chrisstratton]

Hi Everyone -
I want to paint the roof of the bus AND I want to mount solar panels using small "stand off" brackets affixed to the panels - then to the ROOF with VHB tape. Here's the question: I have heard about a problem with VHB tape sticking (or rather not??) to the Tropicool/silcone type paint. What is the best way to get both done - roof paint, panel placement? I considered covering small areas with paintere's tape but that plan would force me into predicting all the landing spots for the panel feet.. Could I possibly sand or otherwise rough up or remove the necessary areas?

While I'm asking - what is good stuff to wash the roof before painting?

TIA!

[Danjo]

You want to tape your panels to the roof? Not too long ago there was heated debate over the use of 1/4-20 bolts through the ribs. Maybe I’m misunderstanding, but if I’m not, understand the amount of force created by the wind and the moving bus. It could be in the 100+ MPH range. A panel coming off into someone’s windshield is a pretty serious thing.

I watched a video on Henry elastomeric application recently. They recommended TSP or TSP substitute or other non-filming detergent. Maybe a scotchbrite pad to cut through oxidation and give the surface some bite.

[musigenesis]

VHB tape is woefully inadequate for attaching roof brackets, even when applied with perfect adhesion. A typical use case for VHB is affixing a lightweight aluminum sheet to the side of a building, with tape all around the edges. For a 5'x8' sheet, this means having nearly 500 square inches of tape supporting maybe 50 pounds of material, with the tape being exposed only to shear stress and not 90° peel-off forces (which tape is worse at resisting). A standoff bracket will only be supported by a few square inches of tape and will face peel-off forces larger than 50 pounds thanks to wind pressure underneath the panels at high speeds.

"Woefully inadequate" is a woefully inadequate term to describe how bad of an idea this is, even if you were to apply the tape directly to bare metal. With paint you would also have to worry about the mechanical strength of the paint, and elastomeric paint is extremely bad in this regard.

There was a guy on reddit who tried to attach his roof deck supports with VHB tape. I was unable to convince him how bad an idea this was, but fortunately his supporting brackets came off in his hand before he even had a chance to try attaching his deck to them.

[Oscar1]

And why are insurance companies dumping Skoolie builds?

[chrisstratton]

Originally Posted by Oscar1

And why are insurance companies dumping Skoolie builds?

Do you post this same question for folks with wood stoves, Mr. Buddy's in sleeping areas, chinese diesel heaters, rooftop wooden decks with no railings, I've even seen someone mount an A/C condenser unit on a 2x10 piece of wood!

At least 3M techs have discussed this rooftop panel adhesion application, which suggests they have considered potential liability exposure there, Renogy and AM Solar promote panel mounting products in the face of product liability.

The question regarding insurance denial does nothing except to IMPLY that there have been expensive failures. Insurance companies don't deny claims for stupidity, they deny based on claim experience

Have there been such claims?? Answering that might actually promote some useful information.

[Oscar1]

Originally Posted by chrisstratton

Do you post this same question for folks with wood stoves, Mr. Buddy's in sleeping areas, chinese diesel heaters, rooftop wooden decks with no railings, I've even seen someone mount an A/C condenser unit on a 2x10 piece of wood!

At least 3M techs have discussed this rooftop panel adhesion application, which suggests they have considered potential liability exposure there, Renogy and AM Solar promote panel mounting products in the face of product liability.

The question regarding insurance denial does nothing except to IMPLY that there have been expensive failures. Insurance companies don't deny claims for stupidity, they deny based on claim experience

Have there been such claims?? Answering that might actually promote some useful information.

As a matter of fact as a former home builder, building inspector and insurance claims investigator I do question the sketchy ideas I see regarding those types of things.
Have a nice day and be safe

[chrisstratton]

To be fair - the whole idea seemed sketchy as all get out to me, on first viewing. Laugh out loud dumb!

The idea that high rise windows are secured with VHB tape both interested and scared me. (here, the window failed - not the method of securing the window: https://www.snopes.com/fact-check/wi...trength-death/)

So - I've kept reading. Will Prouse's promotion of the concept is compelling, as he is a meticulous and opinionated tester and promoter of safety.

Still - I keep asking to learn more.

[chrisstratton]

Originally Posted by Oscar1

As a matter of fact as a former home builder, building inspector and insurance claims investigator I do question the sketchy ideas I see regarding those types of things.
Have a nice day and be safe

To be fair - when I first heard of this, I thought it was laugh out loud dumb. https://www.snopes.com/fact-check/wi...trength-death/ Like that attorney in the snopes article. However, Will Prouse's promotion of the idea gave me cause to investigate further, as Will is meticulously careful and critical in his considerations.

Nonetheless - I'm still questioning the method.

[Oscar1]

Didn’t take too long to find that one.

[Danjo]

Originally Posted by chrisstratton

Do you post this same question for folks with wood stoves, Mr. Buddy's in sleeping areas, chinese diesel heaters, rooftop wooden decks with no railings, I've even seen someone mount an A/C condenser unit on a 2x10 piece of wood!

At least 3M techs have discussed this rooftop panel adhesion application, which suggests they have considered potential liability exposure there, Renogy and AM Solar promote panel mounting products in the face of product liability.

The question regarding insurance denial does nothing except to IMPLY that there have been expensive failures. Insurance companies don't deny claims for stupidity, they deny based on claim experience

Have there been such claims?? Answering that might actually promote some useful information.

Yep, seen a lot of stupid stuff. I’ve also been corrected by this forum for minor infractions of stupidity.

Anyway, there’s at least a couple videos on YouTube from skoolie owners who lost panels while driving. In those instances no one was hurt and there was no other damage, but at 60 MPH in the right conditions one of those things could become a giant metal and glass frisbee and hurt someone.

[Iceni John]

Someone on YouTube with a converted ambulance lost a PV panel while driving; it had just been stuck to the roof, not mechanically bolted. Bad, bad idea.

I have eight 255W panels, and each panel sits in its own support frame to take the loads off the panel's own frame. Each support frame is hinged to a central walkway between the two roof hatches, and the frame's outer edge is supported by two telescoping/hinged/pivoting/sliding stainless struts so the panels can be raised for better insolation. The walkway is through-bolted to 18 of the roof's ribs by 36 stainless 3/8" socket-head bolts and NyLok nuts, and the lift struts are also through-bolted similarly by 36 5/16" bolts, i.e. there are 72 stainless bolts through the ribs holding everything in place. And in case you're wondering about water penetration, there's none at all; I use EPDM rubber washers under SS washers to seal every roof hole.

PLEASE don't even think about sticking or gluing panels down. You'll end up killing someone if a panel comes off and hits a car behind you. Either do it right, or don't do it at all.

John

[melwade]

Tropicool has silicone, which should be avoided at all costs. Silicone will keep anything from ever sticking again, even if you need it too. There are alternative roof paints without silicone.

That being said, the previous comments about VHB tape are spot on. I would never rely on that to hold anything to the roof of my bus!

[Doktari]

How strong are the metal roof screws often used to fasten each Z bracket commonly used on RV roofs for solar?. If 3 screws are used on each bracket that would be strong enough for wind but what about branches? They often gob huge amounts of mastic sealant over the bracket and screws.
Yes, just VHB tape sounds hazardous.
When I was a kid I’d went fishing with a older friend. He loaded a 12 foot aluminum boat on the station wagon roof with clamps. I asked him if he wanted to tie it down more and he declined Well the boat tried to fly away on Interstate 5. It did a full back flip summersault in the air then landed on its nose in the fast lane and stood there with a car hurtling towards it. Maybe a gust of wind came because it fell over onto the shoulder as the car slipped past it. The boat wasn’t damaged badly at all. I’ll never forget seeing a boat summersaulting 20 feet in the air then standing on its nose in the fast lane and the look on the face of the people behind us. Ive taken it seriously and done what the sailors have done for eons which is carry a lot of rope and cord.

[cadillackid]

my problem with adhesives is longevity, i have yet to find ANY that still have the sticking power 5 or 10 years down the road.. now adeshives in addition to fasteners? im all for that as the adhesive can do really well at preventing noise and vibrations that could cause a fastener to fail or back out..



adhesives may work absolutely wonderful for the first X number of months or years but most wont know when they begin to fail.. if 1 out of 4 bolts backs out and you hear your panbels rattling away on the roof then you can fix them.. since generally fasteners are overkill those other 2 or 3 will hold things together till you stop and make emergency repairs..



an adhesive will just start to peel a little at one edge and slowly it works its way across and eventually bam it reaches a point where the whole slab fails and away goes whatever was glues down..



if its mundane like you glue some hanging hooks to your bus walls.. then no big deal when the hooks fall and your bottle of wine crashes on the floor.. but a solar panel whirling through the air???

[Danjo]

I didn’t try to attach the zclips directly to sheet metal. I attached unistrut to the ribs with through bolts and then attached the panels as shown

[Shamoke]

I can see the Dept. of Transportation making a rules change about roof mounted additions to vehicles I.E. Solar panels ect. And knowing the DOT it will be onerous and expensive to follow.

[kidharris]

Originally Posted by chrisstratton

Hi Everyone -
I want to paint the roof of the bus AND I want to mount solar panels using small "stand off" brackets affixed to the panels - then to the ROOF with VHB tape. Here's the question: I have heard about a problem with VHB tape sticking (or rather not??) to the Tropicool/silcone type paint. What is the best way to get both done - roof paint, panel placement? I considered covering small areas with paintere's tape but that plan would force me into predicting all the landing spots for the panel feet.. Could I possibly sand or otherwise rough up or remove the necessary areas?

While I'm asking - what is good stuff to wash the roof before painting?

TIA!

I have never heard of anything that sticks to silicone

[kidharris]

Originally Posted by chrisstratton

To be fair - the whole idea seemed sketchy as all get out to me, on first viewing. Laugh out loud dumb!

The idea that high rise windows are secured with VHB tape both interested and scared me. (here, the window failed - not the method of securing the window: https://www.snopes.com/fact-check/wi...trength-death/)

So - I've kept reading. Will Prouse's promotion of the concept is compelling, as he is a meticulous and opinionated tester and promoter of safety.

Still - I keep asking to learn more.

At least you had the sense to ask..... here is a stupid answer.... if you were tied onto the panel would you rather the panel was taped on or bolted on... in other words would you trust your life to the tape?

[Bon Voyage]

If I were you I’d rethink the tropicool. I have it on my bus and it holds dirt badly so it’ll always dirty looking after any rain etc.. and yes nothing sticks to it. I put a sunroof in which is a piece of clear plastic and sealed it down over the tropicool - it leaks so when it rains because the silicone doesn’t stick. now I have to pull the plastic off scrape the silicone and tropicool off then paint white and reinstall the sunroof. It also leaks at my plumbing vent through the ceiling. One of 2 or 3 big mistakes I made on mine was that tropicool. Just paint it white instead, it’s cheaper and easier

[Rock-N-Ruth]

Originally Posted by chrisstratton

Hi Everyone -
I want to paint the roof of the bus AND I want to mount solar panels using small "stand off" brackets affixed to the panels - then to the ROOF with VHB tape. Here's the question: I have heard about a problem with VHB tape sticking (or rather not??) to the Tropicool/silcone type paint. What is the best way to get both done - roof paint, panel placement? I considered covering small areas with paintere's tape but that plan would force me into predicting all the landing spots for the panel feet.. Could I possibly sand or otherwise rough up or remove the necessary areas?

While I'm asking - what is good stuff to wash the roof before painting?

TIA!

Don't even consider using tape of any sort of tape to fasten your panel mounts. I've got twelve panels on the roof and have built a number of solar systems. You need to consider wind load. If you get enough wind under your panels and the tape fails. You not only lose panels but you take the risk of injuring someone who had no part of your foolishness.

Please take this advice as intended and dont be offended by advice ment to save you and innocent bystanders from a costly mistake.

While I am at it I'll share what I learned when I first put panels on the roof. We live in the desert where the sun cooks the paint off of cars, and frys everything
I thought the panels which cover most of the roof, would shade the roof from the sun. I was wrong. They absorb heat from the sun and emit it towards the roof. Making it even more hot.

Attach your mounts with screws or bolts, preferably to your ribs. Glue at least 1" XPS to the roof under your panels and level an air gap between the panels and the XPS. The panels need to be able to cool or lose a lot of efficiency. You just dont want them to cool by heating your roof.