Good Sam Club Open Roads Forum: Tech Issues: Solar panels vs shade cloth
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 > Solar panels vs shade cloth

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noteven

Turtle Island

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Posted: 07/02/21 12:21pm Link  |  Quote  |  Print  |  Notify Moderator

Has anyone measured roof temperatures in direct sunlight vs underneath a solar panel that is stood off the roof an inch or two on brackets?

I am wondering if panels provide roof cooling like the doubled desert roofs on Land Rovers, Land Cruisers, and "Saudi busses" ?

We have had 4 or 5 clear warm days here - highs in the mid to upper 30s C / high 90s F and warm overnight.

Our sun is high at this time of year. It comes up at 05:00am and sets at 9:50pm.

By mid day on the clear days the air cond is running almost non stop in my camper sitting in direct sunlight.

Today there is some cloud coming through. Immediately after we have cloud shading the air cond starts to catch up and cycle on and off...

So anyways I have thought a shade cloth "awning" that would shade the whole camper roof and walls might make for a more comfortable experience. This trailer has a robust frame and rear bumper that would easily support a double roller affair that could deploy shades side to side...

But such a system would shade rooftop panels when deployed.

So do solar panels act as effective shades or do they begin to pass radiant heat to the roof materials below them and eventually heat up the roof?

RambleOnNW

Pacific Northwest

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Posted: 07/02/21 12:56pm Link  |  Quote  |  Print  |  Notify Moderator

I don’t have RV solar panels but do have them at home. During the super hot weather I measured the temperature on the underside of our uninsulated garage roof using an IR thermometer. The underside of the north side was 118F and the underside of the south side below the solar panels was 107F. The panels are elevated off the roof 5”.


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Boon Docker

Mountain Foothills of Southern Alberta

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Posted: 07/02/21 01:11pm Link  |  Quote  |  Print  |  Notify Moderator

"Has anyone measured roof temperatures in direct sunlight vs underneath a solar panel that is stood off the roof an inch or two on brackets?"

I believe because of the air gap between the panels and the roof it would be a bit cooler at the roof under the panels that not under the panels.

naturist

Lynchburg, VA

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Posted: 07/02/21 01:48pm Link  |  Quote  |  Print  |  Notify Moderator

I, too, lack data, but just from a basic understanding of physics, it would seem reasonable to me that black solar panels with a white back side raised at least an inch or two above any roof would result in significant temperature drop on the roof. The white back side of such panels would not radiate much of the heat created by the black side facing the sun. So I'm not at all surprised by @RambleOnNW's measurements.

Shadecloth would not be expected to result in anything better than solar panels, but I bow to anyone having actually measured the difference.





Lwiddis

Monterey, California

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Posted: 07/02/21 03:22pm Link  |  Quote  |  Print  |  Notify Moderator

Any blockage of direct sunlight on a roof is good…for temperature and UV damage.


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TurnThePage

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Posted: 07/02/21 03:31pm Link  |  Quote  |  Print  |  Notify Moderator

My panels are about 5" above the roof. I don't think any heat transfers from them to the roof. Pure shade.


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Almot

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Posted: 07/02/21 04:18pm Link  |  Quote  |  Print  |  Notify Moderator

When sun is shining directly onto the panels and creating maximum shade footprint, this part of my trailer feels cooler inside. The roof isn't flat, one side of the panel is ~4" above the roof, another side ~2".

noteven

Turtle Island

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Posted: 07/02/21 04:37pm Link  |  Quote  |  Print  |  Notify Moderator

Thank you for the replies.

I notice the uninsulated roof of my cargo trailer radiates heat but it is metal and there is no convective air movement when the trailer is closed up.

I'm thinking a set of panels might make an alright double roof.

The plan is to insulated and do a simple build out to make the enclosed trailer a "mini" toyhauler.

wopachop

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Posted: 07/02/21 07:27pm Link  |  Quote  |  Print  |  Notify Moderator

I've wanted to put camo tent over my roof. Rig a way to roll it up on the front. Cut holes for solar panels to get direct light.

Maybe next summer!

wowens79

Georgia

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Posted: 07/02/21 08:10pm Link  |  Quote  |  Print  |  Notify Moderator

I’m in GA, and have never tried it with an RV, but we have a shade cloth over our deck that gets full afternoon sun. It has made our deck usable in the summer, and as an added bonus shades a French door to our bedroom, and has lowered the temps in that room 5-10 degrees.


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