Flexible solar panels

[jxoco]

I see that some owners have flexible solar panels stuck right to the roof.
I thought that they got hot and we’re supposed to be hung in the wind like on a boat.
Am I way behind the times on this?
It wouldn’t be the first time.

[tdf-texas]

Originally Posted by jxoco

I see that some owners have flexible solar panels stuck right to the roof.
I thought that they got hot and we’re supposed to be hung in the wind like on a boat.
Am I way behind the times on this?
It wouldn’t be the first time.

When attached using thermal tape applied between the solar panel and the roof, any heat generated is dissipated to the trailer shell.

https://www.amazon.com/Ceatech-Therm.../dp/B075F37SQG

[sclifrickson]

Is fiberglass a good thermal conductor? I wouldn’t think so.

[Brian B-P]

Originally Posted by sclifrickson

Is fiberglass a good thermal conductor? I wouldn’t think so.

No, it's not. The tape shown above claims a thermal conductivity of 1.5 W/(mK), which is comparable to porcelain, and glass (not a good thermal conductor) is about 1 W/(mK), but the polyester resin matrix of the fiberglass-reinforced plastic shell is about 0.05 W/(mK). It won't effectively dissipate heat.

[sclifrickson]

Originally Posted by Brian B-P

No, it's not. The tape shown above claims a thermal conductivity of 1.5 W/(mK), which is comparable to porcelain, and glass (not a good thermal conductor) is about 1 W/(mK), but the polyester resin matrix of the fiberglass-reinforced plastic shell is about 0.05 W/(mK). It won't effectively dissipate heat.

So sticking flexible panels direct to the FG, even with the thermal tape, risks reducing their electrical output efficiency when they get hot due to inefficient cooling, yes?

They do look cool though. Even if they’re not.

[Brian B-P]

Originally Posted by sclifrickson

So sticking flexible panels direct to the FG, even with the thermal tape, risks reducing their electrical output efficiency when they get hot due to inefficient cooling, yes?

Yes, potentially, but I don't know if it's actually a problem.

Originally Posted by sclifrickson

They do look cool though. Even if they’re not.

[tdf-texas]

Originally Posted by Brian B-P

No, it's not. The tape shown above claims a thermal conductivity of 1.5 W/(mK), which is comparable to porcelain, and glass (not a good thermal conductor) is about 1 W/(mK), but the polyester resin matrix of the fiberglass-reinforced plastic shell is about 0.05 W/(mK). It won't effectively dissipate heat.

Great example Brian! Using glass as a poor conductor of heat - by the way that is what some cookware is made of because of it's thermal conductivity.

Also, thermal paste is the same 1.5 W/(mK) as the tape. Both are used to conduct heat away from heat sensitive components such as computer CPUs due to it's high heat conductivity.

Below is a chart of thermal conductivity for common materials. Fiberglass is a poor conductor of heat but thermal bonding of the solar panels to the trailer adds mass and surface area which facilitates dissipation of the heat buildup.

Sounds like someone needs to go back and take some refresher courses in thermal engineering. The actual heat dissipation can be calculated using the heat equation. http://tutorial.math.lamar.edu/Class...tEquation.aspx

[Brian B-P]

Originally Posted by tdf-texas

Great example Brian! Using glass as a poor conductor of heat - by the way that is what some cookware is made of because of it's thermal conductivity. :whistling

Glass is used to cook because it is clear, temperature-resistant, and non-metallic. Anyone who has used the old Corning Visions saucepans knows that they conduct heat poorly, and baking times and temperatures are different for glass and metal pans due to the difference in heat conduction. Good thermal conductors are metals, with thermal conductivity running ten times to hundreds of times higher than glass; I note that no metals were listed in the table of "other materials", which probably came with other sections including metals.

Edit: Yes, that was one of three tables in the same online article, including this one for materials which are good thermal conductors:


Applying the panel to the trailer roof insulates the panel.

[Jim Bennett]

I am not going to get into the technical considerations, but I did hordes of research, made my decision, and went with the Lensun semi-flexible panels (four at 60W) which have worked great for 3 years now, taped down on my roof. I believe I was the first (or near) to use them on this site. Not a single issue with their integrity to date.

[Patandlinda]

Originally Posted by Jim Bennett

I am not going to get into the technical considerations, but I did hordes of research, made my decision, and went with the Lensun semi-flexible panels (four at 60W) which have worked great for 3 years now, taped down on my roof. I believe I was the first (or near) to use them on this site. Not a single issue with their integrity to date.

Me neither . About 2 years so far and no issues .our panels are not really flexible but semi-flexible . 1/4 in thick fiberglass backing on trailer roof . Being familiar with a roof fiberglass cooler on home roof , no matter how hot the outside temps , fiberglass cooler does not take on outside heat . Very happy with the Lensun semi- flexible fiberglass backed panels . Pat

[Dave Walter]

Originally Posted by Jim Bennett

I am not going to get into the technical considerations, but I did hordes of research, made my decision, and went with the Lensun semi-flexible panels (four at 60W) which have worked great for 3 years now, taped down on my roof. I believe I was the first (or near) to use them on this site. Not a single issue with their integrity to date.

I used Jim's successful installation as the model for my use of flexible panels on my 15B. Has been a couple years now and we have had no issues at all.

[Ron in BC]

I've had a lifelong knowledge of thermodynamics. Evidently when I was a toddler I touched the top of a cook stove and the first word that I uttered was "hot".

So it looks like the Ceatech tape is used as any other double backed tape whereas the Eterna tape is used more like duct tape in that half is on the panel and half in on the roof.

I did notice a mention of 5 years with the Ceatech tape before performance degrades. I take it that only refers to thermal conductivity.

I'm leaning towards flexible panels on my new 21 but I'm somewhat frustrated by having to use several smaller panels instead of a couple of 100 watt panels. Still haven't figured out which way to go.

Ron

[tdf-texas]

Originally Posted by Ron in BC

So it looks like the Ceatech tape is used as any other double backed tape whereas the Eterna tape is used more like duct tape in that half is on the panel and half in on the roof.

I did notice a mention of 5 years with the Ceatech tape before performance degrades. I take it that only refers to thermal conductivity.

Ron

The 5 yr life is based on operating temps of up to 160 deg C. At the temps the trailer roof operate, the tape should outlast the solar cell.

Here in the Texas sun is about a good worst case test you could find to test solar cell heat buildup.

Measuring the solar cell and surrounding roof temps, I find that the solar cell runs about 11 deg F hotter than the avg roof temp with the temps dropping the further from the solar cell you measure on the roof. The fiberglass surrounding the solar cells do absorb some of the heat from the cells and help reduce the solar cell temps.

[AKCamper]

Hey, how about I jump in here and say that heat dissipation may be a problem, but it does save weight and make a clean installation without holes in the roof. Each to their own and if it works who cares if it isn’t 100% efficient. I personally am going to rig ou two tilting 100 watt panels on my truck canopy and people can find fault with that. It’s all good.

[padlin]

Please keep it civil.

From the forum rules. "Challenge others' points of view and opinions, but do so respectfully and thoughtfully"

[TZBrown]

I also have a Northern Lite fiberglass truck camper.

I installed 2 100W panels on it in 2015 using 3M hi bond tape. there is a slight air gap between the panels and the roof
After 4 years in the sun and snow they still work well and they are still secure to the roof.

If they fail, either in output or bond, I will just get some more.
They are always improving as time goes by.

[jxoco]

As the original poster of this question, I wasn’t concerned with the hundred dollar panels; I was concerned with the roof ( and headliner ) of a twenty thousand dollar trailer. I would have liked to see heat insulating tape not heat transferring tape.
I think I will buy some of those panels because they can stow under a mattress. And I will gain some experience with them.
Thanks for every opinion. Everyone.

[rubicon327]

Originally Posted by jxoco

As the original poster of this question, I wasn’t concerned with the hundred dollar panels; I was concerned with the roof ( and headliner ) of a twenty thousand dollar trailer. I would have liked to see heat insulating tape not heat transferring tape.
I think I will buy some of those panels because they can stow under a mattress. And I will gain some experience with them.
Thanks for every opinion. Everyone.

Not trying to stir the pot but I just happened to come across a tech article on the AM Solar website dated 8/23/18 regarding flexible panels and why they won’t use them. AM Solar is a very well known and reputable RV solar installer. Just wondering if there a reason that the types/brands of panels installed by Escape owners mentioned above or the method of installation or the molded fiberglass roof construction would make this type of panel failure and burning of the roof not applicable? Let’s please keep this as objective as possible because I as well as many others are just researching and trying to understand these different system configurations (and any associated risks) before installing.

[Patandlinda]

Originally Posted by rubicon327

Not trying to stir the pot but I just happened to come across a tech article on the AM Solar website dated 8/23/18 regarding flexible panels and why they won’t use them. AM Solar is a very well known and reputable RV solar installer. Just wondering if there a reason that the types/brands of panels installed by Escape owners mentioned above or the method of installation or the molded fiberglass roof construction would make this type of panel failure and burning of the roof not applicable? Let’s please keep this as objective as possible because I as well as many others are just researching and trying to understand these different system configurations (and any associated risks) before installing.

Respectably Dave not the same panels . Looked and read the article . I remember I bought my Victron charge controller and battery monitor ,before AM solar was offering Victron products . Now I see they are offering their full line . AM solar is one of the best for installing solar and they really care about their reputation for sure . The panels they were showing and referring to were also in my opinion ,very cheap . The panels some of us have installed are very different especially on surface . I just gave trailer a bath a couple days ago and always inspect panels , everything looked as it should . The surface on at least my panels is a mat black not shiny like panels mentioned. The surface on my panels is new technology invented in Japan . Anyway so far happy and hope to get the 10 years they are warranted for . Pat

[Patandlinda]

Originally Posted by Patandlinda

Respectably Dave not the same panels . Looked and read the article . I remember I bought my Victron charge controller and battery monitor ,before AM solar was offering Victron products . Now I see they are offering their full line . AM solar is one of the best for installing solar and they really care about their reputation for sure . The panels they were showing and referring to were also in my opinion ,very cheap . The panels some of us have installed are very different especially on surface . I just gave trailer a bath a couple days ago and always inspect panels , everything looked as it should . The surface on at least my panels is a mat black not shiny like panels mentioned. The surface on my panels is new technology invented in Japan . Anyway so far happy and hope to get the 10 years they are warranted for . Pat

Also had another thought , the cost actually everything to install for me was 585. . For us much better then a 95 watt and not a great solar charger as the Victron at the time at build for us . The exchange also was not very good in 2013 . Article mentioned flexible was expensive . These are really not very flexible because of the fiberglass backing and we have 180 watts. . Pat