Solar newbie questions

[1StreamDream]

I am seriously considering adding solar to my (new to me) 2015 rear twin bed FC, it did *not* come from the factory with any solar, but I do find the pre-wire in the electrical panel area (yellow, green, and blue all unterminated, but tagged solar panel). I am a DIY person, but unsure if I will tackle this yet, my primary paranoia is drilling into the roof, I have so little knowledge of the way the ducted roof is constructed, and how wiring is routed in the airstream in general.

I have not found the other end of the 3 wires, they are not located in the front fantastic fan area, which is the roof area with the most space to place panels. I also have seen many posts suggesting to skip using the factory pre-wire all together, go with heavier gauge, and I am ok to do that but no idea how difficult it is to install such a wiring after the fact.

On a related note, in any permanent mounting of solar panels to the roof (keep in mind I have a 2015 which I understand is the first production year with the "ducted" roof) do I trust the strength of the double sided 3M tape to securely hold panels to that roof, while I might be towing at 70MPH and a cross wind can get under that panel with significant "lift" force ? Or do I drill into the aluminum skin for self-tapping screws and screw right into the aluminum skin ?? Is that enough mechanical strength to hold ? Obviously there are *many* on the road, I just have no idea how the panels are secured to the roof (particularly the ducted roof).

Can anyone guide me regarding the difficulty of pulling new wire (have to be #6 or #8 to be of any real benefit) as I describe, through the interior walls somehow, or an optimal "path" from the roof, up to the front bench location where my electrical panel is located ? I don't find any posts that discuss this particular aspects, so any guidance or insight (or reference to posts that do cover this) is greatly appreciated.

Finally, if there are any recommendations on an installer in the upper midwest (Chicago region) I might end up going that route if I don't like the difficulty of all this.

Thanks in advance

[1StreamDream]

I have located the pre-wire at the rear fantastic fan opening, so I have that much in my favor. I have also decided to at least initially just use the pre-wire. I am heavily leaning toward some Zamp obsidian panels, they put out 20V and per Zamp this further reduces loss between the panel and the controller.

If I add a Victron 100/30 as my solar control, can I leave the factory inverter/charger in place and everything will play together nicely ? I still need to retain the ability for the shore power path to charge the 12V batteries. For now, I will stay with stock batteries, the lithium is so enticing but too much hit on my budget so I am doing what I can to improve my boon docking in bits and pieces.

Also still unsure about mounting the panels to the roof ... see lots of use of the double sided tape, do any of the DIY crowd add a screw (or two) as backup to secure the brackets to the roof ?

[PB_NB]

My thought on the 3m tape is that it is a fantastic product. I would consider adding more mounting brackets to the panels and using a larger foot to attach the the roof.

Drilling holes into the roof skin is not my preference and there are many others that feel this way. I would look at the larger feet to increase the contact area for more 3m tape and then cover it with Sikaflex 221 to keep the water off the tape.

The prewire is great but you will max out the wire capacity of those and if you want to go bigger than say 400W of panels, you would need to increase the wire size from the panels to the batteries.

As far as pulling wires, I was pleasantly surprised about how easy it was to get my new inverter wired to my transfer switch in my Sport 22' as I was able chase the wire under the galley and then under the front bed. There seems to be lots of little spaces to run wires. Running the wires up the wall might be a bit more of a challenge.

I have a few portable panels totalling 265W and found that they didn't do a very good job topping up my big Lithium battery. I am now looking at installing the 100/30 Smart unit and running all my panels into that. I think you are on the right track with that unit.

I will have to check the Zamp website to see about the 20V panels you mentioned.

[waninae39]

Yes vhb tab tap plus simplex atop of the solar panel brackets
Plus look at the victory energy products. Very best products and most reliable
You can access from your phone or the inet

[1StreamDream]

Thanks for the feedback, my next phase will involve a fair amount of work in the electrical distribution area. Mine is under a bench, and I am hoping someone will have guidance to share regarding how I remove some portions of the cabinetry (without damaging them) so the work is possible. Are all these cabinets glued together ? I don't find any screws I would remove to facilitate dis-assembly and I am reluctant to start attempting with a crow bar or pry bar. Also need to get behind the two end panels (into void space I hope) for routing some cabling. I hope to put my victron BM-712 in the upper right end panel but need more access to do it cleanly. Will these things come off ?

[gator.bigfoot]

Originally Posted by 1StreamDream

I have located the pre-wire at the rear fantastic fan opening, so I have that much in my favor. I have also decided to at least initially just use the pre-wire. I am heavily leaning toward some Zamp obsidian panels, they put out 20V and per Zamp this further reduces loss between the panel and the controller.

If I add a Victron 100/30 as my solar control, can I leave the factory inverter/charger in place and everything will play together nicely ? I still need to retain the ability for the shore power path to charge the 12V batteries. For now, I will stay with stock batteries, the lithium is so enticing but too much hit on my budget so I am doing what I can to improve my boon docking in bits and pieces.

Also still unsure about mounting the panels to the roof ... see lots of use of the double sided tape, do any of the DIY crowd add a screw (or two) as backup to secure the brackets to the roof ?

No screws. Just tape and sikaflex. Thousands of panels installed by people on this forum. If done correctly they stay put.

I did a bit by bit install myself. Only because I was fixing one issue and then just decided to get bare minimum for boondocking. It works great. But if you are serious you are better to think this through from the word go. The same panels may not be available later and now you have a mismatch. This hindrance can be overcome but better to just bite the bullet and at least install the panels from the word go so the layout and spacing is correct. I'm actually thinking of removing all my panels if I go bigger and start over. I've already upgraded the prewire so I can go bigger easily. I've got 300 watts now. And only run on solar. Never is my system plugged into ac for charging or running the 12v side. I've never run lower than 84% on the batteries and this was only after 4 days of dark clouds and rain. I don't run much on the inverter, so the the only reason for upgrading would be a coffeemaker or toaster. Otherwise I'm fine with my system.

Think about what you want to use the system for and then decide on how much you need and size your system from there.

[1StreamDream]

Thanks Gator, for sharing your experience. My use case sounds very similar to your description, my only long term objective is to be able to run (somewhat indefinitely) on 12V with the fridge, the water pump, the LP furnace, and the ventilation fans. Not all simultaneous indefinitely, just the ability to use all of the above as needed (somewhat indefinitely). No interest in powering the TV, the microwave, the A/C, etc. from a solar feed.

One question I do have ... you mention only depleting to approx 84%, do you have the original group 24 wet cell batteries ? That is what I still have, and am researching cost effective upgrades to improve my reserve of amp hrs. I have almost no interest in the $2k plus for lithium at the moment, that seems like excess capacity (and too costly) for my goals. I am for sure going to move up to group 27 at the very least at my next battery upgrades, possibly go the 6v golf cart direction but very unsure. Anyhow, if you could share your battery bank details that will help me.

[waltb]

Originally Posted by 1StreamDream

Thanks for the feedback, my next phase will involve a fair amount of work in the electrical distribution area. Mine is under a bench, and I am hoping someone will have guidance to share regarding how I remove some portions of the cabinetry (without damaging them) so the work is possible. Are all these cabinets glued together ? I don't find any screws I would remove to facilitate dis-assembly and I am reluctant to start attempting with a crow bar or pry bar. Also need to get behind the two end panels (into void space I hope) for routing some cabling. I hope to put my victron BM-712 in the upper right end panel but need more access to do it cleanly. Will these things come off ?

I removed my panels by first removing the speakers. Then there are screws up through the speaker holes that hold the panels on.

[gator.bigfoot]

Originally Posted by 1StreamDream

Thanks Gator, for sharing your experience. My use case sounds very similar to your description, my only long term objective is to be able to run (somewhat indefinitely) on 12V with the fridge, the water pump, the LP furnace, and the ventilation fans. Not all simultaneous indefinitely, just the ability to use all of the above as needed (somewhat indefinitely). No interest in powering the TV, the microwave, the A/C, etc. from a solar feed.

One question I do have ... you mention only depleting to approx 84%, do you have the original group 24 wet cell batteries ? That is what I still have, and am researching cost effective upgrades to improve my reserve of amp hrs. I have almost no interest in the $2k plus for lithium at the moment, that seems like excess capacity (and too costly) for my goals. I am for sure going to move up to group 27 at the very least at my next battery upgrades, possibly go the 6v golf cart direction but very unsure. Anyhow, if you could share your battery bank details that will help me.

I have have replaced the original batteries back in 2015 after 9 years of running. I replaced them with the identical Lifelines. I originally bought 2, then the next year bought 2 more so a total of 4. The bank holds out well. I stuffed the extra 2 into the couch arms one on each side. My batteries were group 27 to start with.

[MotoMannequin]

The factory pre-wire is 10 awg so you can do your own calcs to see what that's good for. Our factory panels (2010 International) were 2x65w and 10 gauge was fine. Now we have 4x100w Renogy panels and I wired them series/parallel so that I could continue to use the factory wire. This has advantages and disadvantages. The biggest advantage is obviously reusing the factory wire. In some situations the higher voltage of the series strings (40V open circuit) will allow the MPPT to start in shady situations where a parallel string might not provide enough voltage (in practice I think this probably doesn't matter). The disadvantage is that if one panel in a series string is shaded, then the entire string is limited to the current of the shaded panel.


For mounting, after much hand-wringing I decided VHB tape was the way to go. Then the week before I installed someone here reported losing a panel. Maybe not necessary but I decided to go with VHB and self-tapping screws into the ribs, plus Sikaflex. It gives me a little more piece of mind, and for me anyway, I don't see a few screws in the roof as an extensive addition to the number of holes and seams already in the skin.