Air Deflectors for Solar Panels - Fiberglass RV


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Old 07-06-2015, 12:37 AM   #1
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Name: Charlie Y
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Air Deflectors for Solar Panels

For those futzing with mounting solar panels on the roof, I've installed some deflectors on mine to reduce any risk of freeway airflow getting under the panel and blowing the panel off the roof. ABS plastic bent 45 degrees in segments to follow the roof curvature attached using 3M RP45 VHB tape for 100 pound peel strength. We'll be at the Oregon NOG in Bandon in a couple of weeks if you'd like to check it out.
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Old 07-06-2015, 05:31 AM   #2
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Charlie an alternative to needing deflectors is to use flexible solar panels.

Flexible solar panels are the order of thickness of the material used in your deflectors. Flexible solar panels require no holes since they are held down with double sided tape.
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Old 07-06-2015, 08:21 AM   #3
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Solar

The production of a solar cell is slightly lower when the cell is hot. A roof top array benefits from the 3 or 4" of air space under the panels. A flexible panel with no air space under it will produce less and experience very high temperatures that could contribute to panel deterioration or failure.
I have a 50 watt conventional panel mounted on my roof. The four mounting brackets are fastened to the roof with a total of 8 sq. inches of 3M VHB tape. No screws. The bottom of the panel is 2" above the roof deck.

Norm, didn't your flexible panels fail recently?
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Old 07-06-2015, 09:47 AM   #4
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Originally Posted by starbrightsteve View Post
The production of a solar cell is slightly lower when the cell is hot. A roof top array benefits from the 3 or 4" of air space under the panels.
My 100 watt panel is 2 -3 inches off the fiberglass. I am considering a leading edge air deflector though. Lots of bug corpse build up there not to mention extra drag and consequent lower miles per gallon.

Each style of panel (flexible or rigid) has its own list of advantages and disadvantages. Doesn't seem to be a clear winner either way. I chose rigid based on price, durablility and efficiency. Some folks like the sleek (invisible) look of flexible panels and avoid roof screw penetrations like mortal sin. OTOH an air gap keeps your rig slightly cooler as opposed to turning your fiberglass roof black with a flexible panel. Choose yours to suit your own whim "or religion". Any solar panel is a great addition to your RV and splitting hairs over details gets tiresome.

Best Summer to all, john
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Old 07-06-2015, 12:28 PM   #5
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I'm still debating whether to place my 90 watt panel on the roof or keep it portable. I've been toying with the idea of just adding a smaller 60 watt to the roof so it doesn't get affected as much by the airflow, and keeping the 90 watt available as needed for portability. I do like the ability to move the panel into the sun while in those spots that have lots of shade.
Airflow while towing is one of the issues that concerns me if I mount one on the roof, so the air deflector seems like a good idea. Decisions, decisions!
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Old 07-06-2015, 01:38 PM   #6
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Solar panel failure.

Quote:
Originally Posted by starbrightsteve View Post
The production of a solar cell is slightly lower when the cell is hot. A roof top array benefits from the 3 or 4" of air space under the panels. A flexible panel with no air space under it will produce less and experience very high temperatures that could contribute to panel deterioration or failure.
I have a 50 watt conventional panel mounted on my roof. The four mounting brackets are fastened to the roof with a total of 8 sq. inches of 3M VHB tape. No screws. The bottom of the panel is 2" above the roof deck.

Norm, didn't your flexible panels fail recently?
Steve though we had the panels for a number of years without any issues, I can not say they did failed because of heat. I installed a virtually identical panel on my son's trailer it and it's still functioning. I can say they are designed for boats, a similar panel-to-fiberglass installation.

Per John Linck "an air gap keeps your rig slightly cooler as opposed to turning your fiberglass roof black with a flexible panel"

Since both of my panels failed virtually simultaneously I removed them, separating the vhb tape from the roof in a couple of hours. There was no black mark left on the roof of the trailer, I believe after 3 or 4 years of use. If you're suggesting the black color of the panels makes the inside of the trailer hotter I can't say I've noticed the effect inside the trailer.

As John also stated, it's really not a big deal what you choose. For me I like a lighter, flatter, hidden solution. Many people prefer a solution that they personally setup, that is angle adjustable, ..... It's all fine. It's simply nice to have solar particularly if you want to boondock for long periods in silence.

I have copied this to Preparing a 1991 Scamp where I am writing about installing our Solar panels so it's all in one place.
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Old 07-06-2015, 01:57 PM   #7
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Norm,

That's the first time I've ever heard my interior ABS products need to be painted! None of mine have yellowed, nor of I heard of the issue from hundreds of customers. I've used the same material on the air deflectors, so will find out this summer how well the UV stabilizer works in direct sun.

Charlie Y
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Old 07-06-2015, 02:17 PM   #8
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There was no black mark left on the roof of the trailer, I believe after 3 or 4 years of use.
.
Norm,

Sorry for my unclear statement. I don't expect flexible panels will discolor the white fiberglass in any way. I just pictured in my mind a black object growing quite hot in the sunshine as is lays in contact with the fiberglass roof. Heat will be conducted downwards at a higher rate if there is no insulating air gap. Also a gap below will allow rigid panels to remain at lower operating temperatures than flexible panels since they can cool from both top and bottom, especially if there is a breeze. There will be little cooling downward for flexible panels except that heat which transfers to the RV.

But, since we both seem to prefer camping in cool to moderate temperatures this whole issue may be moot. Folks who camp in warm climes without AC may be more interested.

Also, the differences in service lifetime, efficiency, temperatures, etc. are all pretty small unless your panel's short life is common. A 100 watt panel generates more power than I can use, even without angled orientation. My battery is usually fully charged by the time I finish lunch. So even if it makes a an amp or two more than a flexible panel it doesn't really matter. Your better mpg may be a more valuable result with your streamlined flexible panel. Probably looks better to some as well. And you don't have to look at the bug splatters on the leading edge of my panel.

Its nice we have so many choices and amazing how they multiply each year. I can't wait til some outfit disrupts the RV appliance business and makes us quieter and more energy efficient furnaces, water pumps/heaters, etc. (Suburban and Atwood pay attention. Fantastic Fan is justly feeling the "heat" from MaxxAir.) (Attn. Scamp, Casita, etc. LED's exist and are smart. Are you?) Rant, Rant, Rant. Sorry, as I said at the beginning.

Cheers, john
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Old 07-06-2015, 03:15 PM   #9
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Norm,

That's the first time I've ever heard my interior ABS products need to be painted! None of mine have yellowed, nor of I heard of the issue from hundreds of customers. I've used the same material on the air deflectors, so will find out this summer how well the UV stabilizer works in direct sun.

Charlie Y
Charlie, I was surprised. Maybe it was something else that did it, maybe the heat from my solar panels... just kidding. The outstanding example was the face of the one near the stove. Possibly it was a different issue than UV. If the paint yellows I'll blame Ginny.
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Old 07-06-2015, 03:19 PM   #10
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Originally Posted by John Linck View Post
Norm,

Sorry for my unclear statement. I don't expect flexible panels will discolor the white fiberglass in any way. I just pictured in my mind a black object growing quite hot in the sunshine as is lays in contact with the fiberglass roof. Heat will be conducted downwards at a higher rate if there is no insulating air gap. Also a gap below will allow rigid panels to remain at lower operating temperatures than flexible panels since they can cool from both top and bottom, especially if there is a breeze. There will be little cooling downward for flexible panels except that heat which transfers to the RV.

But, since we both seem to prefer camping in cool to moderate temperatures this whole issue may be moot. Folks who camp in warm climes without AC may be more interested.

Also, the differences in service lifetime, efficiency, temperatures, etc. are all pretty small unless your panel's short life is common. A 100 watt panel generates more power than I can use, even without angled orientation. My battery is usually fully charged by the time I finish lunch. So even if it makes a an amp or two more than a flexible panel it doesn't really matter. Your better mpg may be a more valuable result with your streamlined flexible panel. Probably looks better to some as well. And you don't have to look at the bug splatters on the leading edge of my panel.

Its nice we have so many choices and amazing how they multiply each year. I can't wait til some outfit disrupts the RV appliance business and makes us quieter and more energy efficient furnaces, water pumps/heaters, etc. (Suburban and Atwood pay attention. Fantastic Fan is justly feeling the "heat" from MaxxAir.) (Attn. Scamp, Casita, etc. LED's exist and are smart. Are you?) Rant, Rant, Rant. Sorry, as I said at the beginning.

Cheers, john
I figured out your black comment and amended the heat issue as an after fact. When we installed the first set it was something I checked and really didn't notice much of anything.

We had overnight visitors on there way to Newfoundland. He had a faucet problem requiring replacement so my visiting Nephew and I replaced it for him. His water pump was a lot quieter than mine. I don't know if the solution was a different pump or better isolation/insulation.

As to the furnace we've been able to live happily with a 1500 watt (5000 btu) electric heater. When it's cold we seek electricity. It seems to me that a gas appliance could be made without an associated jet engine, there's not much of a fan on the electric heater. Of course we don't use a Max air, too roof dominant like a roof top AC, just old simple folks here.

We did go to all LEDs in our FL home. I noticed GE has 4 LED 60 watt bulbs at Home Dept for $17. In high usage areas they pay for themselves rather quickly.

Safe Travels John,
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Old 07-06-2015, 03:49 PM   #11
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Originally Posted by tractors1 View Post
Norm,

That's the first time I've ever heard my interior ABS products need to be painted! None of mine have yellowed, nor of I heard of the issue from hundreds of customers. I've used the same material on the air deflectors, so will find out this summer how well the UV stabilizer works in direct sun.

Charlie Y
Charlie, I deleted my comment until I find more out.
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Old 07-07-2015, 09:41 AM   #12
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I have have panels mounted on the roof and no deflector in front of them. I like the air flow and do clean bugs off of the front edge once in awhile. I have had mine mounted for over a year and a half and they are held on with VHB Tape. No problems with them lifting after more than 12,000 miles and all kinds of weather from hot intense sun, snow, and heavy rain storms.

Each panel has about 12 sq. in. of tape holding them in place. Each foot is about 1" wide and 3" long.

If I had to do again, I don't think I would change a thing.
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Old 07-16-2015, 11:49 AM   #13
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The discussion above gave me the motivation to add my homemade air deflector on the leading edge of my solar panel. Not sure how useful it will be in the end but it does seem more streamlined so I might get .002 better MPG. And many insects of the U.S. will no doubt live longer lives. I just bought a sheet of aluminum from the local hardware store and attached it with the 3M VHB tape. I also plan to apply a narrow strip of eternabond tape over the leading edge as insurance. Would have been better if the hardware store had stocked aluminum sheet 26 inches wide like the solar panel, but the splice will work OK. I may even paint it white someday.

You can also see my solar panel mounting in the photos. I used the 3M tape plus a screw into the fiberglass that doesn't penetrate the reflectix insulation, plus a high grade sealant around the base of each support. Probably overkill, but the thought of the panel becoming airborne and going thru someone's windshield motivated me.

You can also see a Camco Vent Cover and a Cellular booster antenna behind the solar panel.

Cheers to all, john
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Old 07-16-2015, 08:01 PM   #14
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Our solar panel travels in the camper. When we set up it slides into two channels on the roof. We take it, and the deep cell battery, in the canoe to power the electric motor.
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