Global Solar 115W PowerFLEX+ BAPV Flexible CIGS Solar Panels

[Yubaman]

My general design criteria is light, low and minimal roof penetrations. The main concern of direct mount solar panels is heat. These panels are used in large roof top installs. Made in Southwest, sold to me by Continuous Resources in Utah. Great company.

There is a single roof penetration.

 

[DavidGraves]

Howdy

So, did you bed them in an adhesive?

What did the retailer suggest?

Thanks

David Graves

 

[Yubaman]

They come with mastic. just peel the backing and lay them down. They are long so you have to measure carefully. They may not be trimmed at all since the vapor barrier might be cut.

 

[Stokeme]

My 120W flex Solar cynergy panels (2) are mounted to an aluminum tube frame which is mounted to my Yakima tracks.
Frame weighs ~5 lbs. Panels are ~5 lbs. There is good air flow underneath panels. Heat has been a major concern as u mentioned. What is different about these panels, re heat? What do they weigh? Are these 12V? How secure is the mastic in travel w/wind & how do you remove them if needed?
I am good with my setup, hopefully for awhile, but these look very interesting for my son’s vintage Ambassador travel trailer.

 

[Yubaman]

you can get the data sheet from Global or Continuous, I have it but its too big to post.....

They are 25 year warrantied, and operating range is up to 185f i believe. I spoke with Global before purchase and they told me that my application was perfect.

The mastic is really strong. There is no sign of any separation. If there is I will sikaflex or something. If they fail the fix is to put another right on top per Global. since they are less that 1/8" thick I am not too worried about it.

They are 12v.

maybe 3-4 lbs a piece est.

BTW I saw your setup and I liked it, just liked this better!!

 

[Vic Harder]

Interesting product line. Looks reputable! https://www.continuousresources.com/

Just to add to the conversation, the noted max temp is 185*F. Nominal is 70*F. Temp coefficient power loss is -.36% per *F. So at 185*F you will suffer a 41.4% reduction in power output.

Does it matter? Probably not; however, I would still want to keep my panels as cool as possible.

 

[Yubaman]

It shouldn't matter to me. I have 220ah of batteries and fairly light loads. I will report back on summer performance.

Thanks for the link Vic. Matt at CR is great to work with. He made a little kit for me including a Victron 15a MPPT, and custom cables. Pricing is fine.

I also bought the Crown1 AGM 6vx2 batteries from him.

 

[Stokeme]

Wow, a 25 year warranty would inspire confidence & ~185F does seems adequate. Proprietary heat barrier? I will have to check these out.
Were you at the FWC Anza Borrego Rally in October? Did we chat?

 

[rustytinbender]

i have fastened lightweight panels to the roof without airspace underneath and they failed. They were covered under warranty but what a mess to get them off. The potential problem is that that when your panels are in direct sunlight in the summer they are going to get very hot,,,very interested to hear how it works out!.

 

[Yubaman]

Wow, a 25 year warranty would inspire confidence & ~185F does seems adequate. Proprietary heat barrier? I will have to check these out.
Were you at the FWC Anza Borrego Rally in October? Did we chat?

Nope, wasn't me, I am new to FWC's

 

[Yubaman]

Interesting product line. Looks reputable! https://www.continuousresources.com/

Just to add to the conversation, the noted max temp is 185*F. Nominal is 70*F. Temp coefficient power loss is -.36% per *F. So at 185*F you will suffer a 41.4% reduction in power output.

Does it matter? Probably not; however, I would still want to keep my panels as cool as possible.

Actually Vic, wouldn't the true measure be the difference between typical heat degradation of racked panels and these direct mount panels?

 

[wildlife2019]

If the solar panels were adhered to a metal surface (aluminum?), I would think the surface would act as a heatsink to dissipate the heat away from the panel better than air could?

 

[DavidGraves]

I also think the roof would be a heat sink.

No doubt the white roof gains some heat, especially in CA or BCS, but I doubt the roof would ever transfer heat TO the solar panel.

It may be we should confine the discussion to panels overheating while parked for long periods...IE YUMA for the whole winter..

Airflow while driving must surely reduce enough heat.

David Graves

 

[Yubaman]

If the solar panels were adhered to a metal surface (aluminum?), I would think the surface would act as a heatsink to dissipate the heat away from the panel better than air could?

This is above my understanding, however the roof is pretty darn thin aluminum without a lot of insulation below it. Should dissipate heat quickly. And David, months of camping is not my MO.

 

[Vic Harder]

Actually Vic, wouldn't the true measure be the difference between typical heat degradation of racked panels and these direct mount panels?

Yes, and that isn't the only variable though. For comparison, I looked up a similar panel to the one I have (which is no longer made... they keep getting more and more watts!):
https://www.solarwholesaler.ca/product/candian-solar-330w-multicrystalline-solar-panel/
which has a a temp coeff of -.41%. Not quite as good as the ones you are using. (.05% difference)

I note that various manufacturers have better temp coeff ratings than others...
https://news.energysage.com/solar-panel-temperature-overheating/

Take that with a ton of salt though, as it appears most of the info on the www indicates it is darn hard to actually determine the temperature of a solar cell during operation https://core.ac.uk/download/pdf/148682287.pdf AND that it is worthwhile to cool a solar array if possible. This paper uses standard solar panels, not flexible ones, and has a readable approach to their testing:
http://www.satnac.org.za/proceedings/2012/papers/WIP_Posters/44.pdf. What I see in the last graphic in that paper is that PV temp roughly follows air temp, given the free-air mounting on an angle so the heated air can rise/flow over the panel.

I still think that mounting flexible panels with no air space under them is not optimal. On a sailboat's Bimini (which is where I think this idea started) heating wouldn't be as much of an issue.

 

[Yubaman]

Yes, and that isn't the only variable though. For comparison, I looked up a similar panel to the one I have (which is no longer made... they keep getting more and more watts!):
https://www.solarwholesaler.ca/product/candian-solar-330w-multicrystalline-solar-panel/
which has a a temp coeff of -.41%. Not quite as good as the ones you are using. (.05% difference)

I note that various manufacturers have better temp coeff ratings than others...
https://news.energysage.com/solar-panel-temperature-overheating/

Take that with a ton of salt though, as it appears most of the info on the www indicates it is darn hard to actually determine the temperature of a solar cell during operation https://core.ac.uk/download/pdf/148682287.pdf AND that it is worthwhile to cool a solar array if possible. This paper uses standard solar panels, not flexible ones, and has a readable approach to their testing:
http://www.satnac.org.za/proceedings/2012/papers/WIP_Posters/44.pdf. What I see in the last graphic in that paper is that PV temp roughly follows air temp, given the free-air mounting on an angle so the heated air can rise/flow over the panel.

I still think that mounting flexible panels with no air space under them is not optimal. On a sailboat's Bimini (which is where I think this idea started) heating wouldn't be as much of an issue.

Here is the way I look at it: if the panels hold up (and they are high quality) then I don't care if output drops in the hottest of weather, as long as they perform to spec. From my research, they are a great company that stands by their products. Besides, I installed 220ah and no current inverter plans so its a light load.

The way they are installed is worth it. Super light and low profile. I am on brushy roads regularly and I am trying to keep the appendages to a minimum. That and the single roof penetration means alot to me. Everyone has there own design criteria for sure.

 

[ckent323]

Unless the flexible panel back surface construction as well as the adhesive is designed to conduct heat the panels may very well heat up to a point that performance is compromised and even to the point that the materials age and break down faster.

Many adhesives are poor thermal conductors.

I am curious what the back surface of the panel is made of and what the adhesive material is. Does anyone know?



Edit: I took a look at the Global installation manual for Mobile (RVs) it shows direct application to the roof. Hopefully they did proper engineering and used thermally conductive materials.

I found no mention of this in their on-line technical materials. I am a bit surprised because it seems to me that a good discussion of it would be a selling point given the history of flexible panel delaminations in the industry. Further, there is no discussion of the power loss with temperature.

Makes me just a bit skeptical.

Edit 2: From their brochure

Certifcations and Warranty* (*Contact GSE for complete warranty terms)
Materials and workmanship - 5 years <== this is important and germane to the discussion on material aging due to heat
Power output - 25 years (90% @ 10 yrs; 80% @ 25 yrs) Limited Warranty

 

[ckent323]

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.com/uploadfile/download/20179261110183184.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.cn/Product/pdf/Crystalline/5a66efd642591.pdf




Caveat emptor!

 

[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.com/uploadfile/download/20179261110183184.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.cn/Product/pdf/Crystalline/5a66efd642591.pdf




Caveat emptor!


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

 

[roverjohn]

Nice work ckent. For those wondering your aluminum roof sheeting is a very poor heat sink, it's too low mass. It's also much too thin to transfer heat from one part of the roof to another.
I do hope these work out though if only because it makes mounting so much simpler.
FWC et all certainly know people like adding solar so adding mounting points during the manufacturing process would seem to make sense. That would at least help future owners from having to drill holes blindly or taking their roof apart.