Find cross pieces under metal roof to mount solar panel?

[Ramblin__Ralph]

I'm going to have someone install a second solar panel on the top of my 2001 Lance 845 TC. I installed the first one (see pic 1), but I'm too old to crawl around on the roof now. Is there some device or technique that I could use to find the cross pieces under the aluminum roof to attach the panel securely? For the first panel I got a drawing (see pic 2) from Lance that shows the roof structure. It's been 15 years, but I think I used it to find the cross pieces by measurement. I'd like to confirm this by a device/technique rather than drill tiny test holes.





Thanks,
Ralph

[Geewizard]

bighatnohorse wrote:
In the event that you cannot find metal substructure I would submit for your consideration using well nuts.
They are inexpensive and you can fail-test them in your garage/work shop by installing them in 1/8-inch luan and attempting to pull them out.
They work.

I tried well nuts and they failed to hold my solar brackets to the degree I wanted.

I chose to use rivnuts (threadserts is another name) and specifically this rivnut kit.

Mine were inserted through the rubber roofing and luan into the hole I drilled in the roof's aluminum tubing. This has worked well for about 15 years.

[Bert_the_Welder]

joerg68 wrote:
On my 2002 Lance, the aluminum sheet roof was loose on top of a layer of plywood, with a thin layer of foam in between. It was not glued down as far as I could tell. That would exclude the no-screws method.

Yep! That would be a problem.
Though, it may not be if there is little lift on the panels. Hell there might even be downward pressure, making them stick better! :W

[joerg68]

On my 2002 Lance, the aluminum sheet roof was loose on top of a layer of plywood, with a thin layer of foam in between. It was not glued down as far as I could tell. That would exclude the no-screws method.

The roof on that camper could be walked on, so I would assume there was a decent layer of plywood (1/4" ?) everywhere. I know there is on my current Northstar camper.

[Bert_the_Welder]

I recently saw someone post they had doubled up the panel "L" mounting brackets so they now looked like "T"'s (basically took two L's and put them back to back). This doubled the contact surface with the roof. They then used the 3M VBM tape to attach the panels to the roof. Then Dicor over top. No screws and had no issues.
Unconventional, but something to consider given you aren't adding more roof holes and you can mount it anywhere on the roof.

[ticki2]

If you feel comfortable that you hit the rafters with the one installed you can use it to measure from to fond the rafters for the new one using the diagram

[StirCrazy]

joerg68 wrote:
Does that camper have an aluminum frame? If it is built like my 2001 Lance 915 was, it has a classic wood frame and an aluminum roof. There is a relatively solid layer of plywood under the aluminum.
You could remove the interior decoration of one of the roof vents; that is pretty easy to do and exposes the layering/construction of the roof.
Depending on the thickness of the plywood, you can bolt the solar panels directly to the roof with some short wood screws, without the need to find additional support.
Seal all holes / screw heads well, goes without saying.
You might also consider to mount an air dam of sorts in front of the panel, so the wind doesn't get underneath it while you drive.

not all. mine said there was but it turns out there wasnt. it only had plywood in the front bit.

Steve

[Ramblin__Ralph]

Thanks for all the tips. My camper definitely has a wood frame. I'll surely try okan-star's method that correlates the inside trim to the horizontal hidden framing members. Very useful to know the framing width, also.

Thanks,
Ralph

[okan-star]

I`m sure its a wood frame , you've got all you need in the diagram from Lance .
Look inside the camper at the ceiling , the trim that runs side to side every 4 foot will give you a starting place to use the Lance layout ,open the vent over the bed and transfer from ceiling to roof , the trim is centered on a framing member , they are 3/4 " wide . The roof is foam core between 3/4" wide x 1 1/2 " framing W/ luon under the sheet aluminum roofing
I would defiantly not just attach to the aluminum and luon . I would defiantly look for framing to screw to .
I just put 4 more 100 watt panels on my Lance Legend 500 added to the 140 watt that I installed years ago .
Use this dicor tape under the panel mts and seal over the screws and around the mts with dicor self leveling caulk

[joerg68]

Does that camper have an aluminum frame? If it is built like my 2001 Lance 915 was, it has a classic wood frame and an aluminum roof. There is a relatively solid layer of plywood under the aluminum.
You could remove the interior decoration of one of the roof vents; that is pretty easy to do and exposes the layering/construction of the roof.
Depending on the thickness of the plywood, you can bolt the solar panels directly to the roof with some short wood screws, without the need to find additional support.
Seal all holes / screw heads well, goes without saying.
You might also consider to mount an air dam of sorts in front of the panel, so the wind doesn't get underneath it while you drive.

[mr_andyj]

Wait for a morning where everything gets covered with dew. The metal frame of camper will have less water condensation on it than the insulated walls or roof and it will be obvious where the steel or aluminum frame is.

[bighatnohorse]

In the event that you cannot find metal substructure I would submit for your consideration using well nuts.
They are inexpensive and you can fail-test them in your garage/work shop by installing them in 1/8-inch luan and attempting to pull them out.
They work.

[KansasKen]

i used a zircon hd900 to find the square tubes under my roof. i borrowed a wallabot and it did not work.