2022 Thor axis

[KFF]

I'm actually just following up on a previous solar power panel thread.
I want to add more panels in addition to my current panel but the Thor schematics says only add accessories in areas where there are backing plates (which of course is where the current panel is located).
Any suggestions to adding panels if there aren't any backing plates?
Thanks in advance.

[Karl404]

Brian at “RV with Tito” https://www.rvwithtito.com/ has a good solution involving T - track and eterna bond tape. I removed the OEM panel and added 4 170 W panels using his method.

[sportcoupe]

RV with Tito also has a fiberglass roof.

The Axis/Vegas has a TPO roof membrane. Think of an awning stretched tight over thin plywood with no or little glue between them. You don't want to use adhesives only to bond to an awning.

Some have successfully use adhesives only (Sikaflex, 3M and VHB tape).

The factory way is to apply Dicor to the bracket bottom, screw the bracket to the roof, then apply Dicor over the screws and brackets.

The factory doesn't pay attention to the areas with backing plates either for the optional 100W solar. My 2022 Vegas 24.1 has the 100W panel off to the right, not center where the backer area is.

I just added three more 100W panels to my roof this weekend. I used Sikaflex 352 between the bracket and roof, screwed the bracket to roof, let cure for 24 hours and applied Dicor over the screws. I hit backers in some areas, some I didn't.

[DavidEM]

I have a 2021 Axis with a single 100 watt panel and a 10A PWM controller. Here is what I would do to add three additional panels:

As noted above, install the three additional panels with screws through the mounting feet and Dicor sealant.

Wire the four panels in series parallel: two pairs of panels wired in series with the two pairs wired together in parallel. This makes them effectively 24V panels which won't work with a PWM controller but halves the current to make it work better with the existing 10 gauge wire. You can do all of this with MC4 connectors or simple crimps. Use #12 gauge to wire them all together.

Remove the 10A PWM controller at the entry way and replace it with a 30A Renogy or Victron MPPT controller. Increase the wire size from the controller to the batteries to #8 gauge. Replace the existing fuse with a 40A near the batteries.

David

[Chateau_Nomad]

Originally Posted by DavidEM

I have a 2021 Axis with a single 100 watt panel and a 10A PWM controller. Here is what I would do to add three additional panels:

As noted above, install the three additional panels with screws through the mounting feet and Dicor sealant.

Wire the four panels in series parallel: two pairs of panels wired in series with the two pairs wired together in parallel. This makes them effectively 24V panels which won't work with a PWM controller but halves the current to make it work better with the existing 10 gauge wire. You can do all of this with MC4 connectors or simple crimps. Use #12 gauge to wire them all together.

Remove the 10A PWM controller at the entry way and replace it with a 30A Renogy or Victron MPPT controller. Increase the wire size from the controller to the batteries to #8 gauge. Replace the existing fuse with a 40A near the batteries.

David

I agree with this plan. Two things: Don't panic about drilling mounting holes in the roof. Look how many things are already on the roof mounted this way. I mounted two panels on our roof and replaced the 10amp PWM controller with a 40amp MPPT controller. I'm not too hung up on brand... shop by price... most come from the same Chinese factory anyway.

NEVER just depend on Dicor sealant as a mounting/adhesive substrate!! It was NOT designed for that... especially for something as heavy as a roof-top solar panel.

Each of my panels are mounted with four feet... two screws in each foot driven into the plywood under the roof membrane. Use a liberal amount of Dicor under the foot, and again completely covering the screw heads... don't scrimp!

Thousands of panels have been mounted this way with no structural problems and NO leaks. And if you ever remove a panel, simply cover the existing holes with Eternabond tape and Dicor self leveling sealant.

[KFF]

Thanks for all the the feedback and instructions!!
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[KFF]

Those diamond questions marks were supposed to be beer glasses.. Cheers and thanks again!

[Karl404]

Good point. I'll keep an eye on it. It seems pretty solid so far. Certainly as solid or more solid than the rest of the original manufacturing. :-) Thanks!

[electric]

Thanks for good advice, especially "don't panic" part
I'm also putting 4 panels on my Vegas and most of them will go without metal backing, so this subject is important to me. Many discussions here are all over the place regarding roof strength and mounting methods, but I came to the same conclusion as DavidEM and Chateau_Nomad, which is "drill baby, drill..."
However, since my panels are 200W, I decided to use 6 brackets per panel rather than 4, to better spread the load on the roof and reduce stress in the middle of the long panel.