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04-01-2021, 05:23 PM
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#1
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Junior Member
Brand: Thor Motor Coach
State: Texas
Posts: 20
THOR #21889
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What's size of the screws should I use for Motorhome roof to mount the solar panel
Hello everyone,
Any one know the size of the screws that I can use for the Thor Motorhome roof to mount the solar panel brackets? I don't know how thick the roof of the motorhome, and don't want use the screw too long to drive through the roof, also don't want use screws too short and can't holding down the panel well.
Thanks.
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04-01-2021, 05:33 PM
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#2
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Senior Member
Brand: Thor Motor Coach
Model: Hurricane 35m
State: North Carolina
Posts: 866
THOR #13505
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Quote:
Originally Posted by Shawn
Hello everyone,
Any one know the size of the screws that I can use for the Thor Motorhome roof to mount the solar panel brackets? I don't know how thick the roof of the motorhome, and don't want use the screw too long to drive through the roof, also don't want use screws too short and can't holding down the panel well.
Thanks.
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If you are still under warranty and you jack with roof, you kill your coverage. Have to have authorized shop install them to not void your warranty.
This is what I used when I had panels installed.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
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Retired Squid who has a Retired Squid that drives him around in a RV!
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04-01-2021, 05:35 PM
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#3
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Senior Member
Brand: Thor Motor Coach
Model: Forest River Forester 235
State: Indiana
Posts: 4,883
THOR #6826
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Quote:
Originally Posted by Shawn
Hello everyone,
Any one know the size of the screws that I can use for the Thor Motorhome roof to mount the solar panel brackets? I don't know how thick the roof of the motorhome, and don't want use the screw too long to drive through the roof, also don't want use screws too short and can't holding down the panel well.
Thanks.
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On mine I used one inch stainless steel sheet metal screws. Probably #8 but I don’t actually remember. I expect 3/4 inch would be fine. My roof (SOB) is only about 1/4 - 3/8 inch thick and the rafters I fastened into are stamped aluminum so added almost no thickness. But the ceiling has a good two inches of insulation so there was no particular risk associated with using longer .
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04-01-2021, 06:50 PM
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#4
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Senior Member
Brand: Thor Motor Coach
Model: THOR Chateua 35SF
State: Florida
Posts: 5,850
THOR #11130
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Liquid Nails works wonders. I wouldn't trust screws...too much flexing underway to trust them staying tight. Most water leaks are found one day to late.
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Now an SOB
Traded Thor for Melbourne Prestige 24NP
2018 THOR Chateau 35SF
Two Labs, Bugsie & Blondie
Blondie passed in 2020 at 5 to Leukemia
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04-01-2021, 07:29 PM
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#5
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Senior Member
Brand: Thor Motor Coach
Model: Vegas 25.6
State: New Mexico
Posts: 5,100
THOR #20220
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my service center same thing under warranty let them do it
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LAS CRUCES 2020 Thor Vegas 25.6
Lora & George. Golden Retriever & Multi-Gen Australian labradoodle & new ALD in March. Happy Campers!! E Biking, Hiking, Tennis, Scuba,Fishing,Cross Country Skiing, Snowshoeing. Retired H.S. Principal, Sr. IT Engineer, Life & Health Insurance Agent
"Today is a Gift and Why it is called the Present"
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04-01-2021, 10:50 PM
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#6
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Senior Member
Brand: Thor Motor Coach
Model: Hurricane 31S
State: Texas
Posts: 4,157
THOR #6411
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Quote:
Originally Posted by Shawn
Hello everyone,
Any one know the size of the screws that I can use for the Thor Motorhome roof to mount the solar panel brackets? I don't know how thick the roof of the motorhome, and don't want use the screw too long to drive through the roof, also don't want use screws too short and can't holding down the panel well.
Thanks.
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You might want to read Tom's blog on the ultimate solar setup. He is a degreed electrical engineer with a lot of idea and actual facts.
<https://mortonsonthemove.com/ultimate-off-grid-rv-solar-power-system-build/>
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Jim & Roy Davis
2016 Hurricane 31S
1961 Rampside in tow
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04-01-2021, 11:38 PM
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#7
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Junior Member
Brand: Thor Motor Coach
State: Texas
Posts: 20
THOR #21889
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Thank you for the reply, my RV is 2019 model, it is out of warranty already.
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04-01-2021, 11:45 PM
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#8
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Senior Member
Brand: Thor Motor Coach
Model: Axis 24.1
State: Connecticut
Posts: 1,773
THOR #20289
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For a Thor, with its TPO roof, I would not rely on just adhesives to attach your solar panels. For fibeglass or aluminum roofs, yes.
But there is a layer of 1/8" or so plywood underneath the TPO that will hold reasonable loads with a wood screw. Macdaddy's Amazon reference above shows #8 or #10 self tapping sheet metal scews tha should work fine. As noted above you only need 3/4-1" length.
Do use a good blob of Dicor or similar sealant above and below the screws.
David
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04-02-2021, 01:28 AM
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#9
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Senior Member
Brand: Thor Motor Coach
Model: Forest River Forester 235
State: Indiana
Posts: 4,883
THOR #6826
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Quote:
Originally Posted by DavidEM
For a Thor, with its TPO roof, I would not rely on just adhesives to attach your solar panels. For fibeglass or aluminum roofs, yes.
But there is a layer of 1/8" or so plywood underneath the TPO that will hold reasonable loads with a wood screw. Macdaddy's Amazon reference above shows #8 or #10 self tapping sheet metal scews tha should work fine. As noted above you only need 3/4-1" length.
Do use a good blob of Dicor or similar sealant above and below the screws.
David
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I located the rafters with a stud finder, predrilled for the screws, injected Dicor into the holes, puddled a good bit of the stuff to bed the brackets and then flooded the brackets and screws when everything was in place. Super strong and zero risk of a leak.
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04-02-2021, 03:27 AM
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#10
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Junior Member
Brand: Thor Motor Coach
State: Texas
Posts: 20
THOR #21889
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Thank you very much.
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04-02-2021, 02:21 PM
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#11
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Senior Member
Brand: Thor Motor Coach
Model: Axis 24.2
State: California
Posts: 134
THOR #18202
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I used well nuts. The expansion of the rubber creates a tight fit and it also provides a waterproof connection. I added lap sealant a an additional protection against moisture. The panels are not going anywhere.
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04-07-2021, 06:48 PM
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#12
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Senior Member
Brand: Thor Motor Coach
Model: 25.4
State: California
Posts: 225
THOR #7440
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I have had the glue down mounts on my AXIS since the first part of 2017, I get on the roof every year with the Dicor to check all joints, the glue Renogy wanted me to use is called Sikaflex an I had to find a special primer from a local construction supply dealer, we get the Santa Ann winds in Southern California and they can take an awning off a rig going through the mountains in a heart beat, if ever they loosen up I will have the option to just add some screws but they assured me if installed correctly they will never come off, I have 4 of the 100 watt panels and they use 6 mounts per panel
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04-07-2021, 10:11 PM
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#13
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Member
Brand: Thor Motor Coach
State: California
Posts: 59
THOR #19337
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I also live in South Cal, with Santa Ana Winds, and freeway speeds.
I have flexible solar panels, and for those I glued them down, glue on the backside and then a bead around the edge. Left some gap on the edge to allow water to escape.
But it depends on your roof, your solar panels, and your own conditions.
Rybie
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04-08-2021, 12:05 AM
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#14
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Member
Brand: Thor Motor Coach
Model: Chateau 22E
State: Quebec
Posts: 31
THOR #18418
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My suggestion : If you want to try drilless mountings, you could install "Renogy Solar Panel Roof Drill-Free Corner Bracket Mount' with Sika Flex (SIKA flex, Multi-Purpose Industrial Grade Polyurethane Sealant & Adhesive) : look on Amazon for details.
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04-08-2021, 01:14 AM
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#15
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Senior Member
Brand: Thor Motor Coach
Model: Four Winds 26B
State: Ohio
Posts: 489
THOR #20900
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FWIW, at highway speeds the panels don't actually experience a lot of high velocity air movement. The air gets pushed up over the roof forming a bubble. If you've seen a boat's wake, it's the same thing, but extended vertically up and over the roof. The actual air movement within the couple inches of the roof where the panels are is pretty low. Most of the forces the mounts need to handle are related to the RV bouncing on rough roads.
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2021 Thor Four Winds 26B on Chevy 4500
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04-08-2021, 01:19 AM
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#16
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Senior Member
Brand: Thor Motor Coach
Model: Vegas 25.6
State: New Mexico
Posts: 5,100
THOR #20220
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My tech guy Kurt has installed 400 solar panels and only
1 has hale damage..he said dicor the hole and dicor
The screws and dicor top of screws
__________________
LAS CRUCES 2020 Thor Vegas 25.6
Lora & George. Golden Retriever & Multi-Gen Australian labradoodle & new ALD in March. Happy Campers!! E Biking, Hiking, Tennis, Scuba,Fishing,Cross Country Skiing, Snowshoeing. Retired H.S. Principal, Sr. IT Engineer, Life & Health Insurance Agent
"Today is a Gift and Why it is called the Present"
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04-08-2021, 01:59 AM
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#17
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Member
Brand: Thor Motor Coach
Model: ACE 27.2
State: California
Posts: 95
THOR #14923
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I used 1” self tapping #10 stainless, and Dicored everything. All good.
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04-08-2021, 02:08 PM
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#18
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Senior Member
Brand: Thor Motor Coach
Model: Forest River Forester 235
State: Indiana
Posts: 4,883
THOR #6826
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Quote:
Originally Posted by atreis
FWIW, at highway speeds the panels don't actually experience a lot of high velocity air movement. The air gets pushed up over the roof forming a bubble. If you've seen a boat's wake, it's the same thing, but extended vertically up and over the roof. The actual air movement within the couple inches of the roof where the panels are is pretty low. Most of the forces the mounts need to handle are related to the RV bouncing on rough roads.
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Not sure how you could know that but my anxiety came from considering the unpredictable gusts from passing an oncoming semi on a two lane with closing speeds that could be 140mph or more. Obviously glued mounts work but I feel safer with screws into structure and figure a few more screws well sealed won’t significantly to the leak of risks given that there’s already 100 or more screws up there.
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04-08-2021, 04:30 PM
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#19
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Senior Member
Brand: Thor Motor Coach
Model: Four Winds 26B
State: Ohio
Posts: 489
THOR #20900
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They don't generally model these things for RVs, but do for semis, trucks and buses. RVs aren't that different though.
Box truck:
Truck Aerodynamics - What & Why? - Aerodyne
The yellow and red are higher wind velocity areas, green is relatively low, blue is very low. You can also see the vacuum at the back of the box from this too.
This paper discusses the aerodynamics of several different configurations of bus:
https://iopscience.iop.org/article/1...2/1/012002/pdf
In several of them, the low velocity area over the roof is pretty clearly visible (esp. Figures 2, 4, and 6).
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2021 Thor Four Winds 26B on Chevy 4500
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04-08-2021, 04:49 PM
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#20
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Senior Member
Brand: Thor Motor Coach
Model: Forest River Forester 235
State: Indiana
Posts: 4,883
THOR #6826
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Quote:
Originally Posted by atreis
They don't generally model these things for RVs, but do for semis, trucks and buses. RVs aren't that different though.
Box truck:
Truck Aerodynamics - What & Why? - Aerodyne
The yellow and red are higher wind velocity areas, green is relatively low, blue is very low. You can also see the vacuum at the back of the box from this too.
This paper discusses the aerodynamics of several different configurations of bus:
https://iopscience.iop.org/article/1...2/1/012002/pdf
In several of them, the low velocity area over the roof is pretty clearly visible (esp. Figures 2, 4, and 6).
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Interesting stuff. Thanks for posting it. Still glad I used screws tho!
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