new solar install - question for those who installed panels on roof

[WilliamKD]

Keeping the weight down as well as keeping the panels as close to the roof as possible is important.

I use a RockPals 100W solar panel https://solwiser.com/am-solar-panel-reviews/ on my roofrack. Obviously 100W is not enough to keep my fridge going alone, but it extent my battery power. While travelling charging is done by the alternator via a PBE dual battery system.

 

[wadventure]

I’m kind of aligning with diddlyv on this.
Struts mounted directly to the roof, ideally tied into the roof beams every four feet.
I think you can also get aluminum unistrut, so there shouldn’t be any dissimilar metal problems.

Possibly the 3M extra sticky two sided tape under the strut and dicor at the bolts.
The strut should distribute load across the entire span that way, and eliminate point loads at individual feet.

@diddlyv, how did that install go, any pics?

 

[Geep]

Living in AZ snow load is not a factor approximately 99.9995% of the time. Spent way to much time in the Infantry wet cold tired and hungry without having a choice to willingly subject myself to those conditions at my age. Your advice about the butyl rubber appears to be sound. The solar panels are 34 lbs each. I received a call from Heartland explaining the roof was essentially constructed with 4ft x roof width aluminum frames filled with styrofoam and apparently no cross ribs. He did not state there was any plywood decking at all. Looking at the roof it appears that there are approximately 2 inch wide frame elements every 4 feet. This will allow a total of 5 or 6 lags per 10 ft strut channel. I will use my stud finder to verify no cross ribs between the visible frame elements. (the roof looks considerably whiter where I presume the ribs are) Not sure I understand the Mounting feet for the strut channel. My plan was mount the strut channel directly on the roof, with or without the butyl tape and every where I put a lag use dicor. If there are indeed no cross members between the 48 inch spaced frame members that would mean mounting a panel between 2 frame elements then having a large gap and mounting the next panel to the frame element 48 inches away. I certainly don't want to anchor anything into styrofoam nor do I want to place mounting squares on the inside of the trailer to solidly anchor the panels thru the whole roof.

Question, who did you contact to get information on you roof. The said they didn’t have that information on my model and suggested using roll up stick on arrays. I already have the panels and my stud finder doesn’t tell me anything.

 

[Bogie]

I had the same problem regarding the the roof structure. To find the trusses, I took down several lights and speakers and used an inspection camera. Then used known landmarks on the on the roof (skylights, vent pipes and measured from these. Also drove some very small brads inside on the ceiling to verify truss locations. Once all was located, I used Unistrut as base rails with the panels bolted to the Unistrut.

You can see some pictures on this thread I posted. https://heartlandowners.org/threads/diy-solar-install.80226/

 

[centerline]

almost ALWAYS, one will get better response to their questions if they dont ask it in an old thread..... start a new thread of your own with the question, and the rest of us that are still active on the forum can help you......


but as im here looking at your question, the unistrut channel is about the best way to mount panels, as it spreads the load of the panels.

the strut channel can run either way on the roof, and to attach it to the roof, start by laying out where the strut cannel will be installed, and mark the linear center line of where the strut needs to lay, extending the line out 2 inches past each end...... then clean the membrane well with a scrub brush or pressure washer... (after it dries, i do a very quick wipe with acetone, without removing the mark)

the strut must have screw holes drilled every foot or so, I always drill 2 holes about 4 inches apart at each end first, then evenly divide the the other holes along its length....

then using dicor self leveling roof patch, lay a hearty bead down the mark on the roof, staying in from each end about 2 inches..... then lay the strut down into the sealant, centering it as per your lay-out..... and install #12 x 3/4" stainless screws.... just til they become snug, as they could easily strip out in the thin underlayment panels..... then use the back of a spoon to fair the sealant, adding more as needed.... I like to make sure there is at least an inch of sealant upward on the side of the strut a bit, and outward from each side of the strut (for the best rigidity and holding power), then, I proof test the screws to see if the strut has settled into the sealant, allowing the scews to be snugged a bit more, before using a shaped piece of wood to fair out the sealant that has extruded up thru the oval holes in the strut, sealing over all the screws and ends of the channel so water has no chance of getting in....

the low profile mounting of the panels wont catch the wind, and as the membrane is glued down to the underlayment, one can glue mounting brackets on top of it, and then use mechanical fasteners help prevent any vibrations from working the glue or sealant loose..... working together, this type of mounting will outperform any other type of low profile mounting system....

ive had my panels mounted this way on my trailer for the past 3 years, and ive been thru wind storms, dust storms, snow, rain, and 85-90 mile per hour winds as I travel down the open road..... without any issues...

and there are 6 other units that ive installed panels on in this same manner, within the past 18 months, which are all doing fine....

I prefer to use the 11/16" high unistrut

caution.... when mounting panels on the roof near the front of the RV, lay the unistrut ACROSS the roof, with the panels only sticking forward of the strut 3-4 inches, so that high winds cant get UNDER the panels, as wind buffeting under the panels is the only way for them to become loose from the roof..... and stay back from the membrane/cap joint, as this may need to be accessed if a leak develops, and so its simple to reseal every couple years....