Flat mounted solar panel on RV roof

Question

All I can find are discussions about solar panel tilt with respect to the sun. What about with respect to water runoff?

Is that an issue? Or can you just mount them flat?

Previous two panels fit near the side walls of the trailer's crowned roof, so when mounted with uniform size brackets they have quite a tilt (1:10?) that allows rain to run off. Still, I see that water puddles on the glass and along the edges. Don't see how that could be eliminated without mounting them at even more extreme angles.

A new panel will only fit closer to the centre of the crowned roof, and so with uniform sized brackets there will only be a tilt of maybe 1:40. But I could modify two of the brackets and increase this if necessary.

Has anybody seen Manufacturer's recommendations one way or another?

dahkota · Answer

We have four mounted on the roof. Three are tilt-able. I don't feel like getting on the roof to tilt them so they are almost always flat. If we will be staying in one place where we need them for a week and tilting them will make a difference, I will get up there and tilt them. We have no problems with water, water runoff, or debris falling from trees. Three of the panels are 2.5 years old and show no signs of water damage or debris damage.

Hope that helps!

scrubjaysnest · Answer

I haven't read anywhere that this is a problem. I suspect not since so many are mounted flat on the roof of rv's.

bfl13 · Answer

Yes, my Sharp panel instructions said to have at least 5 degrees slope so water could run off. They warned about puddles on the glass causing some sort of damage, forget what its called, makes the glass go bad in spots which then cause hot spots and panel cell damage IIRC.

EDIT, here it is:
"• Do not install the module horizontally. Failure to comply may result in excess dirt or white efflorescence (glass disease)."

Even with my tilted panel I get condensation in the mornings this time of year, which holds the dust we get at times. Lately its been that yellow pollen sticking to the wet panel. Seagull poop is worse of course.

It's all work all the time in this RVing business :)

brulaz · Answer

BFL13 wrote:..."• Do not install the module horizontally. Failure to comply may result in excess dirt or white efflorescence (glass disease)."...Even my ~10% tilted panels get filthy when down in Florida. A good cleaning before boondocking is mandatory. And small puddles of water still collect on them. If that's a problem they will need more than 5% tilt as even ~10% doesn't seem to do the trick."Glass disease"? Hmmmm, Call me lazy (true!) but think I'll just risk the ~2% tilt on the new panel. Don't like the idea of higher brackets catching low-hanging tree branches and such. And we'll see if it shorts out before the ~10% tilted panels because of "glass disease". :W EDIT: and thanks for looking that up BFL. I thought I had heard of that that 5% tilt somewhere ...scrubjaysnest: Good to hear from you again, as I don't frequent the Trailmanor owners forum anymore.

twomed · Answer

Mine are flat mounted over the crown 1 inch clearance in the middle, more on the sides.  Five years...minimal washing, no problems. :) :)

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Flat mounted solar panel on RV roof

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