Roof Wiring/Obstacles and Solar Mounting

[DaKevster]

Am a new owner of a 2008 Holiday Rambler 40PLQ and am about to go down the rabbit hole of putting a bunch of solar panels on the roof. I am looking for any insights on where any wiring or important stuff may be run just under the fiberglass/Luan board, so I don’t hit anything. Instead of screwing down each panel individually, my gameplan is to lay down long runs of aluminum strut channel that panels will mount to. Plan is for one strut channel rail to run along the outside edge, just before the roof edge curve starts, and another run roughly a foot from the air conditioner housing. I may also have a set towards the middle, in-between the air conditioners, with strut approx. running length-wise roughly 1-foot either side of the coach centerline.

While this may start a flame-war on attachment methods, my current plan is to bond the strut channel to the roof with polyurethane adhesive (Sikaflex 292i??). Then after curing, increasing adhesion safety by using speed shop rivets https://www.amazon.com/dp/B09ZBLVJFF every few feet. My thinking with the speed shop rivets is that the fingers will spread the load below the fiberglass/luan to hopefully prevent any type of tear-out and reduce chance of adhesive de-bonding, while having a very small penetration hole. That I think would be better than screws, well-nuts, or other mollies that take a big hole. Anyone see a flaw with this plan?

[jacwjames]

Whats you plan on waterproofing the rivets? 

[Tom Cherry]

31 minutes ago, DaKevster said:

Am a new owner of a 2008 Holiday Rambler 40PLQ and am about to go down the rabbit hole of putting a bunch of solar panels on the roof. I am looking for any insights on where any wiring or important stuff may be run just under the fiberglass/Luan board, so I don’t hit anything. Instead of screwing down each panel individually, my gameplan is to lay down long runs of aluminum strut channel that panels will mount to. Plan is for one strut channel rail to run along the outside edge, just before the roof edge curve starts, and another run roughly a foot from the air conditioner housing. I may also have a set towards the middle, in-between the air conditioners, with strut approx. running length-wise roughly 1-foot either side of the coach centerline.

While this may start a flame-war on attachment methods, my current plan is to bond the strut channel to the roof with polyurethane adhesive (Sikaflex 292i??). Then after curing, increasing adhesion safety by using speed shop rivets https://www.amazon.com/dp/B09ZBLVJFF every few feet. My thinking with the speed shop rivets is that the fingers will spread the load below the fiberglass/luan to hopefully prevent any type of tear-out and reduce chance of adhesive de-bonding, while having a very small penetration hole. That I think would be better than screws, well-nuts, or other mollies that take a big hole. Anyone see a flaw with this plan?

Hunt or get info on the factory installed harness and check the wire size and the amp output of your “farm”.  Might be surprised…..that there is an OEM installed harness that will work….but do your homework.  

The OLD SCHOOL method or rule of thumb for the farm….SS screws…metal roofing with fiber washers work….and will absorb the flex and vibration.  SS mounting brackets or Aluminum.  Copious amounts of ProFlex or DiCor Self Leveling “lap” sealer or adhestive.  My favorite as it will sort of “run” behind places where you can’t get a cauling tube nozzle. Don’t forget to lewve a garden walkway path between the platntings in the farm to SAFELY get to the front cap snd such.  Most factory solar panels have a bracket, maybe 2” wide, on each corner.  Mine was a dealer installed Monaco “factory kit”.  

NOW….YOU GET THE BIGGEST THANKS & ATTABOYS I CAN BESTOW.  I have hunted way too many times for the forerunner to these.  USM used to make a 3/16 Aluminum “threaded” Pop rivet.  It had a threaded shank and used a steel mandrel and the shank expanded “full diameter & length” in the hole…so youncould screw in an 8-32 bolts.  These look great for a MH.  MY ONLY CONCERN….over engineering….something that occasionally possesses my brain and I build something that you could mount a Howitzer on. 

I would reconsider  Bottom line….we have a behemoth that is a 4.5 earthquake on wheels.  If you get any flexing…as you will since our roofs are a bit spongy….and the lower the food chain, the “softer” when you walk on them…the “worse” they  feel.  The differences in construction if you browse through the sales brochures from your Ambassador to a Navigator are substantial.  So…personally. A bracket…..maybe 6” max, wide….on each end…(4 total) should be sufficient.  

SO….in retrospect as you seem to really want to “NAIL ‘ER DOWN….and keeping with your comfort zone and practicality….I’d use 3M Marine sealant (3200).  It is tried and proven.  @throgmartin who makes the Guardian Plate kits uses it….so he can give you the correct type.  It HOLDS and will stand up to the weather. Only ONE rivet per BRACKET.  

That’ my thoughts and if i upgraded, based on reading how to mount solar panels here over a 14 year period and drilling holes in my roof and also touching up caulking.  The 3M will seal and then you can put a bead around it..  

I’d also be concerned….going back to the wiring about a rigid absolutely bomb proof wiring channel if you need more ampacety.  Follow the same logic.  Your “wire mold” or surface mounted conduit has to be UV resistant.  It has to have a great deal of thermal expansion and contraction as well as being affixed for movement and  vibration .  Think that one over.  Using 3200 and a rivet every few feet sounds great….but in reality, might be the exact opposite of the application.  Short sections, with interconnecting joint covers and spacing between sections might be best.  We tend to use residential wnd commercial solutions on a surface that moves and such…not the same as a concrete or masonry wall…
 

 

[DaKevster]

18 minutes ago, jacwjames said:

Whats you plan on waterproofing the rivets? 

Dicor self-leveling lap sealant over the rivet head.

[jacwjames]

4 minutes ago, DaKevster said:

Dicor self-leveling lap sealant over the rivet head.

That will work but what about under the angle??  Water will run along it, do you think the adhesive will provide a good enough seal?

[DaKevster]

1 hour ago, jacwjames said:

That will work but what about under the angle??  Water will run along it, do you think the adhesive will provide a good enough seal?

From what I read, Sikaflex 292i is water/salt-water/chemical resistant, marine adhesive/sealant that is used above & below the waterline. If it's strong enough to hold a boat together, I would think it'd be good for this. I could also run a bead of dicor along the outside edge to further protect the adhesive bond. I intend to follow the instructions to the letter. They have specific surface prep and different primers & adhesion promotors for the gelcoat and aluminum sides.

Edited July 24, 2023 by DaKevster

[DaKevster]

19 hours ago, Tom Cherry said:

Hunt or get info on the factory installed harness and check the wire size and the amp output of your “farm”.  Might be surprised…..that there is an OEM installed harness that will work….but do your homework.

 I've looked for any sign of existing solar pre-wire, but don't find one. The panel in the battery cabinet that has the slide control board says "Solar" on the label it, but no sign of extra wires. I haven't pulled the refrigerator vent off, which I hear is a possible location. In any case, I plan on two runs from roof as will be running two MPPT controllers, for redundancy and two smaller controllers are lower cost than one big one. Planning on approx 1800-2200 W, so would be needing 8-10 AWG wire. 

The OLD SCHOOL method or rule of thumb for the farm….SS screws…metal roofing with fiber washers work….and will absorb the flex and vibration.  SS mounting brackets or Aluminum.  Copious amounts of ProFlex or DiCor Self Leveling “lap” sealer or adhestive.  My favorite as it will sort of “run” behind places where you can’t get a cauling tube nozzle. Don’t forget to lewve a garden walkway path between the platntings in the farm to SAFELY get to the front cap snd such.  Most factory solar panels have a bracket, maybe 2” wide, on each corner.  Mine was a dealer installed Monaco “factory kit”.  

Definitely making sure I have a path to get to all parts of the roof.  

NOW….YOU GET THE BIGGEST THANKS & ATTABOYS I CAN BESTOW.  I have hunted way too many times for the forerunner to these.  USM used to make a 3/16 Aluminum “threaded” Pop rivet.  It had a threaded shank and used a steel mandrel and the shank expanded “full diameter & length” in the hole…so youncould screw in an 8-32 bolts.  These look great for a MH.  MY ONLY CONCERN….over engineering….something that occasionally possesses my brain and I build something that you could mount a Howitzer on. 

Hmm...105 Howitzer may come in handy if stop by Quartzite in January, and need to clear a spot. Think I'm going to need bigger channel strut.

I would reconsider  Bottom line….we have a behemoth that is a 4.5 earthquake on wheels.  If you get any flexing…as you will since our roofs are a bit spongy….and the lower the food chain, the “softer” when you walk on them…the “worse” they  feel.  The differences in construction if you browse through the sales brochures from your Ambassador to a Navigator are substantial.  So…personally. A bracket…..maybe 6” max, wide….on each end…(4 total) should be sufficient.  

Part of the logic with the channel strut is to allow for PV panel changes down the road as technology improves, and they may not be exactly the same size. Or I may go completely nuts and put linear actuators on them to auto-tilt them. Strut gives me future options. You do make me think that I could separate into 5-foot sections, for each panel, instead of 2 panels on a 10-foot section. Hoping two 5-footers sections of channel is cheaper than one 10-footer.

SO….in retrospect as you seem to really want to “NAIL ‘ER DOWN….and keeping with your comfort zone and practicality….I’d use 3M Marine sealant (3200).  It is tried and proven.  @throgmartin who makes the Guardian Plate kits uses it….so he can give you the correct type.  It HOLDS and will stand up to the weather. Only ONE rivet per BRACKET.  

Will look at 3M 3200. I know 5200 is super permanent. Everyone has an opinion on which is best.

That’ my thoughts and if i upgraded, based on reading how to mount solar panels here over a 14 year period and drilling holes in my roof and also touching up caulking.  The 3M will seal and then you can put a bead around it..  

I’d also be concerned….going back to the wiring about a rigid absolutely bomb proof wiring channel if you need more ampacety.  Follow the same logic.  Your “wire mold” or surface mounted conduit has to be UV resistant.  It has to have a great deal of thermal expansion and contraction as well as being affixed for movement and  vibration .  Think that one over.  Using 3200 and a rivet every few feet sounds great….but in reality, might be the exact opposite of the application.  Short sections, with interconnecting joint covers and spacing between sections might be best.  We tend to use residential wnd commercial solutions on a surface that moves and such…not the same as a concrete or masonry wall…

I get your point. Will look at just running a strut section for each panel, instead of 10-foot runs. I still think I want the strut running the span of the panel for possible additional bracing in the middle (panels are 5-feet long) or maybe some auto-tilting function. Plus that will better distribute the load from each panel mounting point. And will be running the PV cables in wire loom to protect it, that will then run to a PVC NEMA-4 rated junction box on roof, that'll have string combiner junction blocks and fuses. Then the 2 runs will go down to the electrical cabinet.
 

 

 

[jacwjames]

Do you have a absorption refrigerator (Norcold)?  If you do the solar wiring may be under the vent on the roof, that's where mine is.  There will be a junction box.  On mine Monaco prewired with 8 awg.  The wiring will probably run behind your display panel for the inverter, at least mine does.  That is where they installed my solar control.  They then ran 8 awg all the way to my rear passenger side electrical bay where my disconnects are. But this is a long distance and there is quite a bit of voltage drop.  My controller is 12 volt but if you went with higher voltage panels you'd be able to push more amperage back. 

[DaKevster]

On 7/25/2023 at 11:52 AM, jacwjames said:

Do you have a absorption refrigerator (Norcold)?  If you do the solar wiring may be under the vent on the roof, that's where mine is.  There will be a junction box.  On mine Monaco prewired with 8 awg.  The wiring will probably run behind your display panel for the inverter, at least mine does.  That is where they installed my solar control.  They then ran 8 awg all the way to my rear passenger side electrical bay where my disconnects are. But this is a long distance and there is quite a bit of voltage drop.  My controller is 12 volt but if you went with higher voltage panels you'd be able to push more amperage back. 

I'll pull the vent cover and take a look. The fridge was replaced with a residential, which I plan to replace with a 12v compressor model, but it has a roof vent so assume it was originally an absorbtion fridge. 8 awg would be good size. Guess I could bridge them together at the control panel for one complete run down to battery/inverter cabinet, where plan to have two MPPT controllers, new Inverter and LiFePo4 batteries. Not sure what's going where yet. Still working on the layout.  Would still need a second run for other MPPT controller (2 PV Strings).

Edited July 26, 2023 by DaKevster

[jacwjames]

If nothing else that will give you a good path to the basement to run wires. 

 

FWIW I replaced my dead Norcold with the Samsung RF18 model.  I  only have a bank of 4-6 volt batteries and I can easily go overnight, I stopped overnight in Louisville and parked at Cabela's I ran the generator until ~10:30 and went to bed, 6:30AM I still had 80% showing on the Victron 712 shunt display.  Not bad.  I've contemplated more solar etc but just can't justify it.  I'm either in the heat needing AC or in the cold needing heat and run the generator.  For the times in between it's hard to justify the solar.  If I were full timing and boon docking a lot it would be another story.  I do have 325 watt, just enough to recharge basic useage but not enough to cover the fridge.