46 replies to this topic

[wildlife2019]

Comparing various materials thermal conductivity: 

 

 https://www.engineer...vity-d_429.html

 

fiberglass 0.04

 

aluminum 205  whether it is sufficient enough in this particular discussion to transfer enough heat is another matter.

 

cast iron     58

Edited by wildlife2019, 11 January 2019 - 03:41 PM.

[roverjohn]

I love that someone took the time to find what Cod(83%moisture)'s thermal conductivity is, 0.54. Just happens to be 2.7x higher than Butter(15% moisture)'s. I never would have guessed that.

Edited by roverjohn, 11 January 2019 - 07:04 PM.

[rando]

Has any actually determined that the reason that the semi-flexible panels had a high failure rate was actually due to heat dissipation issues?  There is a lot of 'internet lore' about this, but I have not seen anything that actually conclusively identifies this as the issue.  There were some photos circulating showing burnt spots on semi-flexible panels, but to me that suggests a mechanical failure causing a high resistance junction in the circuit, resulting in localized heating, not a bulk heat dissipation issue. 

 

My last set of solar blvd panels died from hail damage, so I switched back to my older rigid panel, but I would eventually like to go back to the lighter panels. 

[roverjohn]

Another thing I find interesting about this discussion is that people seem to think you need to drill a bunch of holes in your roof and then seal them to prevent/delay leaks.

While the glass panels are certainly heavier the newish ultra high bond strength adhesives are pretty amazing. There really is no reason not to trust them in this sort of application.

Just glue down some mounting points and then bolt your panels to them. The OP's design intent seems to be to keep the panels as low as possible so this idea really would not be useful for him.

This will not answer rando's query but the failed flex panels I've seen all had opaque outer layers and laminate separation both of which would likely be sped up by introducing heat into the equation. The important thing is not really why they might fail but the time it takes them to fail. The first would be nice to know but potentially irrelevant if they last long enough.

Edited by roverjohn, 11 January 2019 - 07:22 PM.

[Stokeme]

If you can fashion an aluminum type tube frame, & attach to Yakima tracks, u can be low & light with no holes in the roof.

[Yubaman]

The Global flexible solar panel brochure lists the adhesive but I do not see anything the back surface material the cells are mounted to.

The adhesive is ADCO HelioBondTM PVA 600BT butyl mastic

I looked at both the Global site and the ADCO Corp site and did not find any thermal conductivity data for the adhesive nor did I find any discussion of thermal conductivity to the RV roof.

Sure seems like a marketing oversight. just hope it isn't an engineering oversight too.

Typical butyl rubbers (or mastics) are lousy thermal conductors (good thermal insulators).

Edit: Digging deeper the panels at the following (China) link sure look the same as the Global panels but Global claims their panels are made in the US. What do they mean made in the US?

http://www.sinoltech...61110183184.pdf


Edit 2: Global is owned by Hanergy. Hanergy is a Chinese company

https://en.wikipedia.org/wiki/Hanergy

Edit 3: and here it is

SINOLTECH COOPERTION WITH HANERGY: SINOLTECH becomes authorized cooperator with Hanergy in year 2015. Representing brand “Global Solar”, “Miasole” and “Solibro” CIGS Modules in overseas market.

https://www.enf.com....66efd642591.pdf




Caveat emptor!


Good questions, I will hopefully have a response in a couple of days.

[Yubaman]

The Global flexible solar panel brochure lists the adhesive but I do not see anything the back surface material the cells are mounted to.
The adhesive is ADCO HelioBondTM PVA 600BT butyl mastic
I looked at both the Global site and the ADCO Corp site and did not find any thermal conductivity data for the adhesive nor did I find any discussion of thermal conductivity to the RV roof.
Sure seems like a marketing oversight. just hope it isn't an engineering oversight too.
Typical butyl rubbers (or mastics) are lousy thermal conductors (good thermal insulators).
Edit: Digging deeper the panels at the following (China) link sure look the same as the Global panels but Global claims their panels are made in the US. What do they mean made in the US?http://www.sinoltech...61110183184.pdf
Edit 2: Global is owned by Hanergy. Hanergy is a Chinese companyhttps://en.wikipedia.org/wiki/Hanergy
Edit 3: and here it is
SINOLTECH COOPERTION WITH HANERGY: SINOLTECH becomes authorized cooperator with Hanergy in year 2015. Representing brand “Global Solar”, “Miasole” and “Solibro” CIGS Modules in overseas market.https://www.enf.com....66efd642591.pdf
Caveat emptor!
Good questions, I will hopefully have a response in a couple of days.

This from Matt at Continous Resources. I am in the backcountry and using a mobile phone for this. BTW you can buy them without mastic.


Hi Greg,
Global Solar was acquired by the Hanergy Company which is an overseas company.

With that being said, the panels are made and tested in the US (Arizona). They are specifically tested in the Arizona heat.

This video will help explain a lot:


I will ask Global Solar for more info regarding the heat question.




I'll keep you posted,

MATT DALLEY
President/CEO

[DavidGraves]

On the subject of gluing down weld studs or some other base mount, I would try to glue it over the roof rafters....this being the only area the roof itself is adhered to the camper.

 

Between the longitudinal rafters there is nothing but a thin skin.

 

I say this in relation to the assorted wind loads/lift on ANYTHING attached to your camper roof while driving at speed .

 

David Graves

[lostcreek]

I have 2 100W Global Solar flat panels on my Phoenix aluminum roof, 3 years old.  Am very happy with them.  The surface is quite durable through many of the rough bushy/treed back roads I've been on.  No sign of lifting off.  Some scratches but I can't find any measurable impact on amps generated.  Only downside seems to be that the edges are peeling up a bit, allowing water to seep into the plastic border area.  I've layed down some aluminum tape to help seal that, but no damage yet to the silicon generating areas.  The wires and junctions are fine too.  Vast majority of days are in the Western US sun, I'm sure the panels get very hot, but plenty of power for my needs.

 

Until now these panels were not available retail (that I could find), only thru dealers/manufacturers.

[DavidGraves]

Thanks for the report.

 

I met a Phoenix owner last year who also was pleased with his flex panels which had been installed by Phoenix.

 

David Graves

Edited by DavidGraves, 13 January 2019 - 12:34 AM.