Comment: Solar Power

Does anyone have any info on the flexible type of solar panels stuck directly onto the roof of a caravan. The idea appeals to me as they are lighter, forms to the shape of the roof, no gap for rubbish to collect under and are less noticeable. But are they still efficient or much less so than the others. I would appreciate some knowledge, not just opinions. PeterC50
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Reply By: Member - Lisa & Peter (NSW) - Thursday, Sep 11, 2014 at 14:03

Thursday, Sep 11, 2014 at 14:03
We added two 90 watt panels to our existing panel before our last trip. Very happy with them, very light and efficiency seems similar to others though I am no expert.
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Follow Up By: Member - Lisa & Peter (NSW) - Thursday, Sep 11, 2014 at 15:16

Thursday, Sep 11, 2014 at 15:16
Our roof pops up at an angle so that helps a bit
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Reply By: Member - Frank P (NSW) - Thursday, Sep 11, 2014 at 14:36

Thursday, Sep 11, 2014 at 14:36
Hello Peter,

I put 4 x 50 watt thin panels on the fibreglass roof of my Kimberley Karavan.

Putting aside the strength of the sunlight and other uncontrollable factors there are two major factors that will affect efficiency of the panels

- orientation with respect to the sun
- temperature of the panels.

If they are fixed to your roof you cannot orient them for max efficiency.

And, if they are fixed flat on the roof they get no ventilation underneath and get hot. How hot depends on your roof. Mine's fibreglass so it doesn't carry much heat away so the cells get pretty hot.

The best I've seen out of my 200 watts on the roof is 130 watts. Most times it is about 100 watts (measured). Not much return on investment so not for everyone, but in my power hungry setup it is a handy extra to my portable panels.

Cheers

FrankP

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Follow Up By: Les PK Ranger - Thursday, Sep 11, 2014 at 14:41

Thursday, Sep 11, 2014 at 14:41
Also add cleanliness to that list of things that affect efficiency.
Just need to ensure they are clean and dust free.
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Follow Up By: Member - Frank P (NSW) - Thursday, Sep 11, 2014 at 17:23

Thursday, Sep 11, 2014 at 17:23
Of course, Les, I should have remembered to include that. After a dusty drive I do clean them prior to setting up

And just to be fair to the panels and not distort the discussion, part of the lowish performance on my van is due to the sloped roof sections where the panels are mounted, so at no time are they ever both properly aligned to the sun - even less so than horizontal panels.

FrankP

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Follow Up By: Member - Rosss - Thursday, Sep 11, 2014 at 17:40

Thursday, Sep 11, 2014 at 17:40
Hi Frank, I have 2 the same as yours, have not stuck them on yet, but use them as portable at the moment, what did you stick them down with?

Cheers Ross.
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Follow Up By: Member - Frank P (NSW) - Thursday, Sep 11, 2014 at 18:12

Thursday, Sep 11, 2014 at 18:12
Hi Ross,

I used Sikaflex Marine Sealant Adhesive 291.

Good preparation is essential as I found out to my cost when one peeled off and had to be replaced :-(

You have to thoroughly de-wax the fibreglass and clean the panels' aluminium backing after you remove the protective film. I didn't do that well enough and one lifted, though I suspect it may have had a vandal's helping hand as the TRAILING edge of another panel had been lifted with something that bent and stretched the aluminium base.

I removed them all (no mean feat as they were well stuck), cleaned everything and re-installed with the addition of some small screws on the edges. The pic above is the original installation with no screws.

I have since found out there is a Sikaflex primer available which probably should be used.

My panels were retro-fits, obviously. The Kimberley factory now fit these as standard (without the external junction boxes). They don't use safety screws as I did. I don't know what glue they use.

Cheers

FrankP

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Reply By: skulldug - Thursday, Sep 11, 2014 at 16:47

Thursday, Sep 11, 2014 at 16:47
Hi Peter,

I have just put two 135 w semi flexible panels on my van. I got them through solar4rvs who have tested direct stick panels compared to the same panels with an air gap. There was some loss of efficiency from memory but not much. The results are on his website.

The owner Phil, was very helpful with advice I could understand. He also has an excellent calculator for determining your needs.

If flexible panels appeal because of weight, I suggest you also have a look at lithium ion phosphate batteries. They weigh half that of AGM and on paper, perform better.

Just my thoughts but based on the set up I have.

Skull
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Reply By: noggins - Thursday, Sep 11, 2014 at 20:41

Thursday, Sep 11, 2014 at 20:41
I have 4 x 80w x 7.5A flexible panels on the roof of my van feeding a 30A PWM controller.
Best I've got out from them so far is 28A on a low battery, fully charged by 11 Am.

I glued them down with Sikaflex Pro using 2 thicknesses of double sided tape to get the sealant thickness right for the job.
My van's roof has a ''floating skin'' meaning it isn't fixed down all over, and when the panels get a bit hot from the full sun the roof just lifts a bit and becomes almost tike a heat sink for the panels.

I contacted the suppliers re yellowing of the panels from uv.
Best we could come up with after discussion with their engineers was to clean and use a headlamp type sealer on them if they ever discolored .

Ron
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Follow Up By: Member - Frank P (NSW) - Thursday, Sep 11, 2014 at 21:46

Thursday, Sep 11, 2014 at 21:46
Ron,

I had a bit of yellowing on my panels. I polished it out with the fibreglass polish I use on the van - Septone Boatcare Fibreglass Polish - Superfine.

What is the headlamp sealer you used, and to what effect?

Cheers
FrankP

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Follow Up By: noggins - Thursday, Sep 11, 2014 at 23:10

Thursday, Sep 11, 2014 at 23:10
I haven't had to do it yet but places like Repco sell it a a headlamp restoration kit with superfine emery and polisher as well as a sealer that protects the lens cover from the Au harsh UV

I have some left over somewhere in the man cave ( shed) that I used on my Hyundai, stopped the yellowing and the cover stayed clear till I sold the SUV ( no idea what happened after that ;) )



Ron
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Follow Up By: Member - Frank P (NSW) - Friday, Sep 12, 2014 at 07:00

Friday, Sep 12, 2014 at 07:00
Thanks Ron. I'll hunt around Repco, Peps and Supercheap.

Cheers
FrankP

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