OK for solar panel to overhang rear edge of RV?

[Visionquest]

I want to add a second solar panel to my RV roof in such a way that I can travel with it flat and tilt it while in storage during winter months. The rear of my RV faces almost due south while in its outdoor storage space. By mounting the panel at the rear of the RV with a slight bit of overhang I expect snow to fall right off on to the ground 12 feet below. The tilt will also optimize the winter solar performance. During our travels (March through Oct) performance will be best by leaving it flat as well as I won't want to drive with the leading edge of the panel catching air!

My other factor is the rear AC unit which will not allow the panel to sit fully flat on the roof. It will have to overhang the rear edge of the roof by about 6-8". (panel is 200w approx 5' x 2'). See attached graphic.

I'm looking for input on whether this overhang would be acceptable. I would plan buy or fabricate the rail mounting such that the mounting is cantilevered off the roof, giving the trailing edge of the panel full support.

Thanks in advance for your input.

 

[justinm001]

Mine overhang off the sides a few inches. They're mounted 11.5 inches in actually as it's inside the awning. Just made my 1st 3 hr trip no problems and was super windy.

 

[sumpower]

You can legally overhang a vehicle up to three feet in most states.
My only concern is if overhanging the back of the RV, the road grime will cover it. So you will probably have to clean it more often.

 

[0truck0]

I doubt road grime gets up 12 feet that much.
Mine overhangs off the back by 6-10 inches or so. Yes, legal under 3 feet and if over 3 feet then you need a red flag like you would if you have a ladder hanging off the roof. I hope this is not a question about legality, if so then Im out...

The overhang might even give you better aerodynamics. I doubt you see it in mpg calculations, but it will be there.
I like that the overhang keeps water off the rear wall too.

Pic of left side panel hanging off the rear (left of pic) by a few inches. Metal roof, aluminum angle iron taped on and screwed to panel. Angle iron at front edge of panel all the way across the short side and screwed in. I have two panels on either side hanging off the back. Was just not enough room to get it all way on roof and avoid AC shadows.

How to do it? What are you working with exactly? What is the roof made of? Will you be screwing brackets on or using tape?
I dont want to go into every possible way you can attach but if you provide a little info we can help a little.

I had a truck camper once and I mounted one 100w panel off the back and made it double as a rear door awning. About half the width of the panel was off the roof.

 

[Visionquest]

I doubt road grime gets up 12 feet that much.
Mine overhangs off the back by 6-10 inches or so. Yes, legal under 3 feet and if over 3 feet then you need a red flag like you would if you have a ladder hanging off the roof. I hope this is not a question about legality, if so then Im out...

The overhang might even give you better aerodynamics. I doubt you see it in mpg calculations, but it will be there.
I like that the overhang keeps water off the rear wall too.
View attachment 217382
Pic of left side panel hanging off the rear (left of pic) by a few inches. Metal roof, aluminum angle iron taped on and screwed to panel. Angle iron at front edge of panel all the way across the short side and screwed in. I have two panels on either side hanging off the back. Was just not enough room to get it all way on roof and avoid AC shadows.

How to do it? What are you working with exactly? What is the roof made of? Will you be screwing brackets on or using tape?
I dont want to go into every possible way you can attach but if you provide a little info we can help a little.

I had a truck camper once and I mounted one 100w panel off the back and made it double as a rear door awning. About half the width of the panel was off the roof.

Thanks. Its a fiberglass roof so I will be screwing anchors into it. I also thought about it providing a small amount of protection for the rear window like a small awning. I'm looking at using this tilt mount and installing so that the bottom rails overhang by about 6-8".

 

[Visionquest]

photo of tiltable mount being considered.

 

[0truck0]

Fiberglass like a boat or fiberglass like a moving truck with thin flimsy roof transparent panel? If like a boat then do not screw in and damage roof for no reason, VHB tape is all you will ever need. If it is a flimsy fiberglass panel then maybe tape is enough, just depends on how much flex the panel has to it. If flimsy then you have to hit something solid other than a flimsy panel for it to hold. Use tape and screws, but hit something solid. Holes can be slow-death for an RV, be very very wary of putting holes in no matter how confident you are to seal them. One drop of water once per month will rot out an RV over time....

 

[richard cabesa]

3M 5200, the devils glue.

 

[0truck0]

3M 5200, the devils glue.

is it removable? 3M VHB tape is with a heat gun. Make sure you can remove it bc you will re-do the panels at some point.

 

[richard cabesa]

No, it's permanent !!!

 

[Visionquest]

All good suggestions for mounting. Using tape will make me nervous about how well it will secure a panel but I agree avoiding screw holes is likely a good idea. I like the 3M 5200 route.

I don't know exactly the make up of the roof but when I replaced a SiriusXM antenna the thickness of the top layer at that spot was easily over an inch.