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Old 07-19-15, 10:13 PM   #1
doug30293
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Default Tracking vs flat panels

Hi All;

I've been out of commission for awhile so forgive me if the subject was covered. I couldn't find anything in my search.

I am preparing a 30 foot 5th wheel trailer for long term snowbirding. We have a campground membership that provides utilities but I would like to spend time away from RV parks as much as possible.

400 watts of PV seems adequate for my needs. I could simply slap four panels on the roof and be done with it. But I have all this aluminum, CNC equipment, and an inherent desire to complicate things as much as possible.

Has anyone built a solar tracking array for an RV? Since weight is important I am trying to balance the array framework against another panel or two.

I am not keen on the idea of putting the array on the ground - too much set up and risk of damage.

Thanks;
Doug

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Old 07-20-15, 01:28 PM   #2
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The gain you get from tracking is about like adding one extra panel, in many cases.
What you might want is to roof mount and be able to elevate one end of the panels,
to get the best angle on the sun (depending on time of year).

I had a branch fall on one of my ground-mounted panels and make some hair-line cracks..
They were invisible, but water got in and now the panel is starting to die..
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Old 07-20-15, 09:25 PM   #3
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My guess with rv you might be confined a little by the orientation of the lot you are assigned. In the south were the snowbirds migrate flat is a good compromise. But with less sun and more angle in the winter time it would be nice to be able to put some extra tilt to gain some extra rays.
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Old 07-20-15, 09:43 PM   #4
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Can you get away with flat in Austin during the winter?
Flat would be best, in case you ever took off and forgot they were at the up angle..
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Old 07-21-15, 08:30 AM   #5
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At about 40 pounds per panel I could probably add a fifth panel with less weight gain than the tilt structure. There will be some structure in either case as I do not want to attach the panels directly to the EPDM-skinned roof.

I will be constrained to lot orientation when staying in a park. But they provide the electricity as part of the package so I wouldn't need the PV's during those stays. Dry camping on Federal land offers more flexibility but I would still prefer to park without having to worry about PV orientation. I guess that makes a flat array the best choice.

One more option is to mount the array as an adjustable awning over the port side bump-out. This bump-out is 13 feet long and has considerable solar heat gain. The weight and cost of the array would be partially mitigated by not having to install a dedicated awning. Complexity and potential for damage are the main concerns with this approach.

How durable are the backs of the panels? For the awning scenario I am thinking of having the glass side against the side of the trailer when stored for travel.

Doug
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Old 07-21-15, 09:31 AM   #6
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Not durable. About as breakable as the front side. The backs of mine are just a thin plastic coating..
Solar Back Sheet, PV Back Sheet; Solar Cell Back Sheet material designed for high dielectric strength and weatherability - Dunmore Corp

A good wack from either side, is going to break the glass and you can kiss it goodbye..

http://ecorenovator.org/forum/45979-post52.html
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Old 07-21-15, 03:34 PM   #7
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Branches, such as the one that got your panel, are what concern me. The safest place for the PV's seems to be inline and behind the rooftop AC unit. That should provide the best protection as it is also below the crest of the roof. I can get them far enough aback from the AC condenser to avoid heating them.

The bump-out awning will just have to be a separate issue.

Doug
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Old 07-24-15, 08:19 AM   #8
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I have a neighbor with a flat array on his house. According to our well trained city rebate guy flat is better than west or east if your roof and surroundings wont allow south. If your worried about driving off make a kill switch or alarm that requires the panels down. We had those on the live news vans to keep people from forgetting to lower the mast before driving off...worked most of the time until one photographer put a wedge in its place so he could adjust the truck position with the mast up, then forgot about it and drove off at the end of the show.
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Old 07-24-15, 09:04 AM   #9
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LOL!! Reminds me of the time I drove our Mazda 626 into the garage with a used Table Tennis table on the roof racks..
It had long legs with little wheels sticking up into the air.. The hardware had rusted solid.
I was going to WD40 them, and off-load the table, before parking in the garage!
Not too much damage.. Just some small dents in the door, to remind me..
'Don't do dat'!


http://solarelectricityhandbook.com/...alculator.html
In Austin, I would set them up for 60deg and forget about tweaking..
It's just too hot to be messing around with in the summer (or spring and fall)..
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Old 07-25-15, 03:28 PM   #10
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Some years ago, a fellow at Quartzite was displaying a beautifully built and engineered tracking setup for about $2,000. even then with panels at around $4/watt it was less expensive just to add a panel.
Avoid moving parts whenever possible, they fail.

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