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Solar panel drag question
#768786 December 21st 2020 8:58 am
Joined: Sep 2020
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Fly_Low Offline OP
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Hi, all. New to the forum. Will definitely get some pics and info in the introduction forum, but have a pressing problem first.

I've mounted 3 100w renogy panels to the top of our '85 G20 High-top Conversion van. I took out the original 3/4" (!!!) screws that were holding the down the rack and then drilled all the way through the roof and secured the rack with 2 inch bolts with locking nuts and washers. The bolts go through plywood squares that provide even more support for the bolts on the inside ceiling of the van. There's also a layer of butyl tape underneath each mount on the top of the van. For the panels I used a combo of the mounts that renogy sends you and u-bolts to attach them to the rack itself. The panels are held together with galvanized metal brackets. Everything is secured with locking nuts and washers. The panels are super solid on there. You can rock the entire van with the panels.

My problem is that at speeds above 55 the outer edges of the panels really start to get shaking. Braking is also somewhat affected because even if the panels weren't wobbling before braking, when I apply the brakes I suppose that the dip towards the front causes some turbulence. As you can see the back of the rack sits higher than the front so the panel naturally angles up. Also there is 15" of overhang of over the back. Having them sit much flatter is not really an option. I "might" be able to get the back down by about an inch, but it would be very difficult because of clearance issues. Mounting them flat to the roof is not an option because of all the contours of the roof.

Any suggestions would be much appreciated. Btw, the pipe insulation under the middle panel is because I noticed that a couple times the roof had flexed enough to tap the bottom of the middle panels bolts (which are slightly shorter than the outer panels bolts because of that hump in the middle of the roof. I don't think that movement will happen now that I have started the ceiling in the van and have crossbeams attached to the existing ceiling supports which hopefully takes away the torsion of the fiberglass.

Would drilling holes across the top back of all of the panels help the air flow through easier? Would some kind of wind deflector across the front help out? I joined the panels at the very top with shorter lengths of the metal bracket. Would having a full length one up there be better and cause less shaking?

Thank you all so much!

Attached Files IMG-1446.JPGIMG-1428.JPGIMG-1448.JPGIMG-1450.JPGIMG-1452.JPG
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Re: Solar panel drag question
Fly_Low #768795 December 21st 2020 10:55 am
Joined: Sep 2005
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carpal tunnel
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Welcome!
Remember, you asked.
If those panels can flex, they will die! They ain't built to bend. You know what they cost (not cheap!!)
My advice would be to remove the panels, the "luggage" rack and the vent.
Fiberglass up the vent opening and the rack mounting holes and the holes you've made.
Build a full perimeter frame with a middle cross beam to support the panels (like a bed frame) that will leave about 2" underneath and not allow them to flex.
Mount the frame and reinstall your vent farther forward.
Lottsa work but needed.
Look on van life and solar forums and on youtube for inspiration and info. Some have built hinged, tilting frames to catch more sun while parked that work really well. On each side mount hinges with the pins replaced with long bolts so that either side can be unlatched and raised to catch that morning and evening sun.

My 2%...

Re: Solar panel drag question
Fly_Low #768796 December 21st 2020 11:35 am
Joined: Mar 2019
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Is it an option to separate the panels? Looks like you maybe able to fit one on each side of the vent, and the third horizontally in the luggage rack. If not, then only other option is to really move or remove the vent and make them lay flat. I feel like it's acting like a bad spoiler since air is getting under it and around it and it's not contoured to have the air flow around it like that.

Re: Solar panel drag question
Fly_Low #768807 December 21st 2020 5:12 pm
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First of all, Welcome.

Second, Ditto to what Catfish and Juntao said. All valid points to take note of.

Third, here are my thoughts.

We have a similar rack set up and we did the same thing removing the tiny screws that held it in place and drilling holes all the way through with reinforcement on the inside. Knock on wood- 10 years later we've had no problems with the rack loosening or anything of the sort.

In our case, we removed the AC unit that was in the middle of our rack and closed up the hole. Then we secured our 135 panel to the rack crosswise. Although it can catch some air we have had negligible notice of this compared to the AC unit that was there before. We have contemplated another panel now and then and have assessed that either side or in front of the central roof vent or on the front of the roof before the two windows would be the best options.

While you might be able to throw some sort of wind dam in the front of your set up to bring air up and over the panels you will still have sweeping around issues. I guess you could dam up the sides as well but as already mentioned these panels are not meant to flex so that should be a priority.

Also, don't know where you are from or where you plan to travel and stay but if you haven't been out west and are finding only highway wind to get to them, they would for sure be a gonner once you hit the winds of the west.

Best go with a flat secured at all edges design in my opinion and experience. Besides being more aerodynamic they are way more stealthy and since your rig is already very stealthy looking it sure would make it easier for you to be low key in locations where you needed to be.

Good luck!


Nicole
1988 Dodge B250 5.9l 360 Ram CamperVan / 727 Tranny / Rochester Quadrajet Carb
www.nikothenomad.blogspot.com
Re: Solar panel drag question
Fly_Low #768835 December 22nd 2020 8:24 am
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Thanks so much for the replies. Was hoping that I'd have been able to shore up the frame, but looks like I'm back to square one. Moving the vent isn't really an option right now because of time constraints and the winter weather and having to work outside. Will be mounting one on either side of the vent and one across the back. I think I'll mount them the same way by drilling through the roof and reinforcing with plywood on the inside. Does anyone have experience with only using VHB tape? I have a roll, but I'm a little terrified to only use the tape to hold on the panels! Do I have to remove the paint from the fiberglass before putting the tape on? I'm worried it would just peel the paint off and go flying!

Re: Solar panel drag question
Fly_Low #768838 December 22nd 2020 11:55 am
Joined: Jun 2010
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These might be good to keep the profile down ... peel N stick just lock down the leading edge


https://www.amazon.com/Uni-Solar-PVL-136-inches-Flexible-Easiest/dp/B00HOU6A12


SUNSHINE VANS-VAN DIEGO
ADRENALIN BY THE GALLON & CHASIN RACIN
ONE FOR THE DIRT & ONE FOR THE STREETS
'93 CHEVY G30 454 4X4 SPORTVAN EXT 146" WB
'92 CHEVY G30 454 BEAUVILLE EXT 146" WB
Re: Solar panel drag question
Fly_Low #768853 December 22nd 2020 7:57 pm
Joined: Jun 2010
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Don't know if you are now planning on totally flat but everything I know says you do need an air gap of an inch or so at least flowing under them because panels get hot. Check with your panel manufacturer to be sure. If you don't mount it on a rack I would look at z angle brackets as that is what everyone I know has used to mount directly to the roof.

An example.... https://www.etsy.com/listing/736376420/solar-panel-z-brackets-set-of-4-mount?gpla=1&gao=1&&utm_source=bing&utm_medium=cpc&utm_campaign=shopping_us_all&utm_custom1=_k_afa602df81661dc206825d3d06d438aa_k_&utm_content=bing_319339186_1310617986645934_81913644654434_pla-4585513245482005:pla-4585513245482005_c__736376420&utm_custom2=319339186&msclkid=afa602df81661dc206825d3d06d438aa


Nicole
1988 Dodge B250 5.9l 360 Ram CamperVan / 727 Tranny / Rochester Quadrajet Carb
www.nikothenomad.blogspot.com
Re: Solar panel drag question
Fly_Low #768854 December 22nd 2020 7:58 pm
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Sorry that link didn't transfer. Just copy and paste it into your browser. Or do a search for 'z bracket solar panel'


Nicole
1988 Dodge B250 5.9l 360 Ram CamperVan / 727 Tranny / Rochester Quadrajet Carb
www.nikothenomad.blogspot.com
Re: Solar panel drag question
Fly_Low #768903 December 23rd 2020 4:33 pm
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Wow, never saw a solar panel spoiler before. I am surprised the Renogy panels held up to that much force/stress at 55mph. I have a 100 watt renogy framed mono panel that Is a portable unmounted panel, and am not impressed with how the corners of the frame are joined. I'd be using some more aluminum and rivets to reinforce those corners if the panel were subjected to more regular stress

That unisolar linke friske1 provided, well I have the 68 watt version, Unisolar is defunct since 2012 or so, and the 136 watt panel is something like 18 feet long.

besides you already have 300 watts of framed panels.

There is no rule that all 3 panels have to be touching each other.

Space under the panels is for heat removal purposes, but that 1 inch minimum rule is also for houses, with flat roofs. A flat solar panel on a curved fiberglass roof will accellerate any wind movement under the panel, and ventilate it. So perhaps one corner of the panel on a curved roof should have at least an inch of space to allow air movement when parked, but one corner can almost be in contact with teh curved roof to keep the profile down. I've got a 130 watt kyocera on my roof since 2007 and the one corner closest to the middle/highest point only has 3/8" gap. I was not willing to raise it any higher, and would now lay that corner flush or nearly so, with the roof if I were to do it over.

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