Flexible or conventional solar panels for TC?

[Boatycall]

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?

[Fastbrit]

Installed them on my camper. bought from Amazon.
In the first year performance was the same as hard panel, but now 3 years after I get almost nothing out of them.
I should have opted for hard panelI

[HMS_Beagle]

I have used flexible panels on boats, along with many of my friends.

First of all, the semi-flexible panels can be made with the same monocrystalline cells as rigid panels. You are not going to find the most efficient ones in a $99 panel, whether flexible or rigid. Long ago, flexible and semi-flexible panels were only made with amorphous or polycrystalline cells which aren't as area efficient. The best semi flexible panels are as efficient in area as the best rigid panels.

Second, It isn't just heat transference to the roof or longevity: panel output is rated under "standard" conditions which means a panel at 77 deg surface temp. As most of you know, they will run well above that on a sunny day. As the temp goes up, the output goes down, and the drop is significant - up to 30 or 40 percent less when very hot. Having space behind the panels cools them some. It isn't tremendous difference but it helps.

Third, semi-flexible monocrystalline panels have issues with delamination, even the very best brands costing $800/panel. This is a constant headache on boats, where rigid panels are impractical in many situations. Most are guaranteed for a long time for output, but for a very short time for delamination. For this reason alone, I would use rigid panels if they can be practically used. The only time I would use semi-flexible is if they were required to sit directly on top of a curved surface, or you had to walk on them. I have $5000 of semi-flexible panels on my boat, the finest brand at the time made in Germany. About half of them have now failed from delamination, the first happened only 3 years in. My experience is typical compared to other boat owners I talk to.

[maxum1989]

I went the flexible panel route on my camper. Partly for weight savings and partly because it was easy to secure the flexible panel directly to my Northern lite fiberglass roof without drilling any holes. I used eternabond tape around the edges. I wouldn't have been confident gluing brackets down to hold a glass panel up there. If the panel fails I can just cut the tape where it overlaps the panel and remove to put another in its place.
I have a 100 watt panel on the roof and a second 100 watt panel I use as a portable that is wired into the same controller. The flexible panels work great for portable use as they are very lightweight (about 4lbs) and store nicely under the upper mattress.
I cannot speak to efficiency as this is my first go at solar so I have nothing to compare it to, but my panels produce right at their rated specs so I have no complaints.

[Geewizard]

Wankel7 wrote:

Geewizard wrote:
I suggest conventional panels. Airflow beneath the panels, when mounted using Z brackets, helps keep it cool and the flexible panels are just not as efficient as a good monocrystalline panel.

However, I also suggest not putting more panels on the roof and going with portable panels....unless you always plan to park in the sun while stationary.

Not much extra space in a truck camper for ground deploy panels though ....

Sure is in mine....and my truck.

[Bedlam]

bighatnohorse wrote:

Bedlam wrote:
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?

Could one not remove a failed panel and simply glue the replacement on top?

That would be my solution to a failed panel, but now you are adding weight and bulk which is what you were trying to minimize by going with adhesive panels in the first place.

[Wankel7]

Geewizard wrote:
I suggest conventional panels. Airflow beneath the panels, when mounted using Z brackets, helps keep it cool and the flexible panels are just not as efficient as a good monocrystalline panel.

However, I also suggest not putting more panels on the roof and going with portable panels....unless you always plan to park in the sun while stationary.

Not much extra space in a truck camper for ground deploy panels though ....

[ulvik]

In my experience flexible panels that are permanently attached to a surface seam to over heat. You have to understand a solar panel operates at its best when it is as cool as possible. I have heard from multiple sources that panels need air circulation to keep them cool to insure longevity. Plus once they are permanently attached what are you going to do if it fails? In my opinion a quality conventional panel bolted to the roof with a little clearance under them is the only way to go. JMO!

[Geewizard]

I suggest conventional panels. Airflow beneath the panels, when mounted using Z brackets, helps keep it cool and the flexible panels are just not as efficient as a good monocrystalline panel.

However, I also suggest not putting more panels on the roof and going with portable panels....unless you always plan to park in the sun while stationary.

[bighatnohorse]

Bedlam wrote:
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?

Could one not remove a failed panel and simply glue the replacement on top?

[Ductape]

I'm interested in this discussion because I'll soon be doing another install on a new rig. Used large framed panels last time, but the flexible panels would be less weight and more aerodynamic.

[Camper_Jeff___K]

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...

[work2much]

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.

[Wankel7]

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

[Lwiddis]

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?