Forum Discussion

Boatycall's avatar
Boatycall
Explorer
Jan 06, 2018

Flexible or conventional solar panels for TC?

My questions pertain only to physical mounting on my TC. I'm an electrical engineer, and already have done several solar setups. I have 600w of solar right now on the Shotwagon (my trailer in the sig pic). I use them through 6 batts in the trailer, then to a 4ga umbilical from the trailer to the TC to keep the TC charged.

I have no solar on the TC, and I'm considering adding a Morning Star mppt (same one as the shotwagon) and solar to the TC. The panels on the Shotwagon are peel-n-stick Unisolar flexible panels, on a tin roof.

I saw Amazon had these on sale for $99. No self-adhesive backing, and feedback is "ok", not spectacular, but they're very lightweight. I'm thinking 5-6 of them, depending on how many fit. 6 would be ideal, since i could run them in series-parallel in two high-voltage banks to a mppt, which is how my Shotwagon is set up.
Flexible panels on sale for $99

Conventional panels are more "Tried and true" and seem to have better feedback. Cost is irrelevant since they're both relatively the same price.

For those who have put solar on TC rubber roofs - your thoughts?
  • The Wynns review flexible panels

    Seems a lot of people who use flexible panels aren't happy with them. Personally, I'm partial to monocrystalline panels for the highest efficiency in limited space. You can also get a little heat relief from the high hot summer sun beating down upon you.
    That will be 2 cents...
  • Wankel7 wrote:
    Can you fit bigger panels on your roof?

    If 600 watts is your goal I would accomplish this with the least number of panels as possible. 6 panels are a lot of wiring and mounting.

    My guess is if you did 3 175 watt panels you would have the same power going to your charge controller as you would with 6 100 watt panels due to less total wiring and lower resistance.

    Additionally, if you have any panel tilting aspirations panels glued to your roof won't allow that.

    I have no connection to these panels but I have been eyeing them for a future install.

    https://www.ebay.com/itm/1-175-Watt-12-Volt-Battery-Charger-Solar-Panel-Off-Grid-RV-Boat-175-watt-total/272812576939?hash=item3f84e590ab:g:2uYAAOSw-29ZXumz


    I agree although it's good to try and stay as far as possible from possible shading from things like the Air conditioner if possible. Also allow room to walk around on the roof to clean panels and maintenance. Panels in the 160-180 watt range are often good sizes for full size campers.

    The cab over on TC's is a good spot away from shading and slightly angled so parking towards the sun helps their production a little. These are 180 watt panels.

  • Can you fit bigger panels on your roof?

    If 600 watts is your goal I would accomplish this with the least number of panels as possible. 6 panels are a lot of wiring and mounting.

    My guess is if you did 3 175 watt panels you would have the same power going to your charge controller as you would with 6 100 watt panels due to less total wiring and lower resistance.

    Additionally, if you have any panel tilting aspirations panels glued to your roof won't allow that.

    I have no connection to these panels but I have been eyeing them for a future install.

    https://www.ebay.com/itm/1-175-Watt-12-Volt-Battery-Charger-Solar-Panel-Off-Grid-RV-Boat-175-watt-total/272812576939?hash=item3f84e590ab:g:2uYAAOSw-29ZXumz
  • Work2much wrote...”This is only speculation but it is my belief that panels spaced off the top of the rood will transmit less heat into the RV by providing sun shading and heat ventilation/escape. The glass panels get very hot. I assume that flexible panels do as well.”

    I believe that to be true. Any other opinions?
  • A perimeter bead of dicor would probably keep a flexible panel down. Although it's not fun to remove you could certainly remove a panel later. Either that or eternabond tape around the edges. Later just cut the panel loose and leave the tape on the roof.

    600 Watts should be very doable on your 1160. You could probably get 900 or more.
  • You all make very good points. I hadn't considered heat transference of sticking them on the roof vs. the shade and an air gap provided by conventional panels.
    And I do plan on covering most of the exposed acreage up there with panels. My goal is 600w.
    The flexible panels are not self-adhesive, they have eyelets like a blue tarp or flag does, but a lot of people I've read about are using liquid nail to stick them down. To to Bedlam's point, ya, if one fried I'd be up a creek if I stuck them down vs. screwed them down somehow.
  • I have used conventional panels only so I can't compare performance. I have installed them on both rubber and TPO roofs with no issues. This is only speculation but it is my belief that panels spaced off the top of the rood will transmit less heat into the RV by providing sun shading and heat ventilation/escape. The glass panels get very hot. I assume that flexible panels do as well.
  • Since this thread is a comparision question I want to piggyback one more ,
    With conventional panels having an air space between the panel and the roof, and flexible being directly on the roof, is there a significant difference in the summer as to heat in the rig from the dark surface and lack of an airspace?
  • My only concern with the peel and stick type panels is if there is a failure. How will you replace it without damaging the roof?