Flexible solar panels with adhesive

GaryKelly · Guru

Flexible solar panels with adhesive

dragonfly1 · Senior Member

Garry

For a solar panel to work at it's best it needs air under it to keep it cool so I am not sure how they would perform

Dragonfly1

oldbobsbus · Guru

Two things..

1. they need to be able to cool down when working so by sticking them down they will disperse the heat into your roof..

2. How do you get them off if they fail and you need to repair or replace them.. smile

Be a devil Gary and get a couple of strips of Aluminum angle bent up at your local sheetmetal shop and glue and screw that to PJ...

Brenda and Alan · Guru

Gary we had flexible panels fitted early this year on our 2003 vintage van (Al roof). they are bonded with a sikaflex adhesive and they are like the proverbial s**t to a blanket. I don't think they will ever come loose. The heating does occur and causes some creaking as the panels heat and cool with sun /shade changes. To date they produce about 65% of their theoretical out put but not yet summer sun though. I would expect an efficiency of about 70-75% in full summer sun. We have been travelling in the south of WA SA and Vic. Loss of output is easily over come by fitting more panels to compensate and as weight is not a problem it is easily done. We are very pleased with these panels as we have not had to plug in to charge batteries since fitting. We consume about 40Ah per day from our 12v system and have 360 watts of panels.

Alan

D and D · Guru

Here's some info I found on the web that gives a couple of options for fitting flexible panels to the roof of RVs - www.solarfuture.com.au/solar-panel-info-3/solar-panel-info/.There maybe something there for you Gary - the zipper option looks interesting.

Dave

Reed · Senior Member

dragonfly1 is correct. Flexible solar panels have slightly less efficiency and heat decreases the efficiency as well. However, an awful lot of folks in US (and apparently a lot of folks in Australia and NZ as well from reading the different fora) attach flexible panels through: adhesive, Velcro and just screwing on the flexible panels.

One article described the effect of temperature as "...each degree over 25˚C (of the panel) the maximum power of the panel is reduced by 0.48%..."
Reed and Elaine

Plendo · Guru

The performance of all solar cells reduces as they heat up away from their optimum operating temperature. The traditional heavy panels which use a glass sheet for protection and strength, are typically mounted with an air gap, thus allowing air to access the back of the panel which provides some cooling.

The flexible panels use a plastic structure, and are typically glued down to an underlying structure, thus they transfer heat to the structure they are glued to.

I measured my flexible panels in full sun before i fitted them to the roof of my van, and they regularly measured in at 73 degrees on the back of the panel. A white roof structure beside the panel was only getting to about 52 degrees in the same conditions. I did not want to increase the temperature of my van roof by 20+ degrees, so chose to mount the panels on top of 10mm of insulation.

The temperature coefficients are listed below, and at 73 degrees my 100W panels should be producing 83W

Given the chance again, I would use the same panels, but I would mount them differently by making up light metal trays to sit them on, and elevating these trays away from the roof, best of both worlds. I reckon I could keep the weight under 2kg per 100W.

Temp. coeff. Pmax		-0.38%/°C
Temp. coeff. Voc		-0.27%/°C
Temp. coeff. Isc		0.05%/°C

GaryKelly · Guru

Interesting info, Plendo. The shallow aluminium trays sound like a good idea but they would need to be screwed to the roof, right? I was hoping to avoid drilling holes.

And thanks for the link D&D. You've added a bit extra to the URL but it works if you remove ".there" and end the link at info/ www.solarfuture.com.au/solar-panel-info-3/solar-panel-info/

Another option I have is to remove the old BP solar panel which came with the camper. The panel is probably 10-15 years old and according to one bloke is about 60 watts. If I bought a new, more efficient 200 watt panel, I could dump the old BP and use the frame that's already there (or at least the holes if the frame size needs to be altered). I reckon 200 watts and 2 x 105ah deep cycles will be sufficient for my needs.

oldbobsbus · Guru

GaryKelly wrote:
Interesting info, Plendo. The shallow aluminium trays sound like a good idea but they would need to be screwed to the roof, right? I was hoping to avoid drilling holes.

And thanks for the link D&D. You've added a bit extra to the URL but it works if you remove ".there" and end the link at info/ www.solarfuture.com.au/solar-panel-info-3/solar-panel-info/

Another option I have is to remove the old BP solar panel which came with the camper. The panel is probably 10-15 years old and according to one bloke is about 60 watts. If I bought a new, more efficient 200 watt panel, I could dump the old BP and use the frame that's already there (or at least the holes if the frame size needs to be altered). I reckon 200 watts and 2 x 105ah deep cycles will be sufficient for my needs.

Ya could maybe use the old mounts that are already there to mount the new panel.. smile

May need a little modifying but that shouldn't be a problem..

Blue · Senior Member

Gary...

as long as the surface has been cleaned properly you can just stick the damn things on...

normal solar panels have around 10 to 12% efficiency while the flexible solar panels have 20 to 22% ... not the other way around...

use Fuller Toolbox Silicon.. its the ducks guts of Silicones to hold stuff on..

http://www.hbfuller.com.au/products/trade/multi-use

this stuff is currently holding my solar panel on which is on brackets..

im going to upgrade to 2 x Flexible 115 Watt Panels soon and I will simply stick them on with the above silicon..

http://www.ebay.com.au/itm/Flexible-Solar-Panel-115Watt-12v-Charging-Systems-/221564027756?ssPageName=STRK:MESE:IT

Blue · Senior Member

in this panel we only have 4 legs.. silicon under the feet as well as over the top of the feet..

you have to cut it off with a sharp stanly knife if you ever want to get it off again

GaryKelly · Guru

Thanks everyone for the replies and comments. Lemme get something straight here... there are two types of flexible solar... totally flexible film with an adhesive backing (like vinyl sheeting for furniture) and semi flexible panels with an aluminium frame that needs to be mounted. I was originally referring to the film in my opening post, and not the semi flexible panels.

I was toying with the idea of sticking solar film directly onto my camper roof. But I've changed my mind. The roof of the camper is old, for one thing, and ribbed, so it's not a clean smooth surface.

So you got me a little confused there, Blue. Yours is framed (in the picture) with mounts, so it's semi flexible.

In any case, I've decided to reuse the existing mounts/brackets of the old BP panel on my camper, dump the BP, and install a new 200 watt semi flexible in its place. If what Blue says about semi flexibles being more efficient than standard rigid panels, then a 200 watt semi flex should provide plenty of power. Am I correct?

Plendo · Guru

Sorry to come back and risk confusing the issue, BUT I think there is some misunderstanding that has perhaps been generated by the people advertising solar panels.

The cells used to make solar panels (the squaring black bits) are all cut from blocks of cultured silicon, now most use the higher quality mono crystalline structure, which is capable of achieving about 26% conversion efficiency in lab conditions, however in a production situation most are achieving between 18 and 22%. The main factors affecting the cell efficiency are the quality of the doping (how well the surface of the panel has been converted into a diode), the texture on the surface of the cell (how much light it absorbs, or reflects), and the amount of shading structure on the surface of the cell (the wires).

Once these cells are converted into panels, the performance of the protective clear layer comes into play, be it glass of a clear plastic in the case of the semi flexible panels.

Thus the performance of semi flexible panels and rigid panels alike is dependent on the quality of the cells used, and the quality of the clear protective layer. There are good and not so good examples in both types of panel. Perhaps the percentage of poor flexible panels may be slightly lower, as they are made as a premium product.

How do you tell?

1. Do not accept what the seller says as gospel, as he is probably not telling you everything you need to know (he probably does not know).

2. To give yourself a guide, work out how many watts you are getting per square meter of panel, in the case of the panels I am using the manufacturer claims 100W and the panel area is 0.56 sqm (1.04 * .54), therefore they should get 178w/sqm. I regard this as reasonable, but far from the best , or the worst panel on the market.

Semi flexible panels are not better than rigid panels, or the other way round. Semi flexible are significantly lighter (1.3kg / 100w, versus 12kg/100w), but they are also about three times the price.

It comes down to how much weight matters to you.

Blue · Senior Member

Gary..

I only posted that picture to show you that its held on by the Toolbox Silicone and nothing else..

its just a normal 120 watt solar panel

forget screwing into the top of your van you only need that type of silicone..

if you lived close by I could show you.. ah well..

Blue · Senior Member

i'll see if I can get a closer picture of how I've attached that panel today gary..

but I have to help my daughter shift house again first..

-- Edited by Blue on Saturday 11th of October 2014 08:40:51 AM

toglhot · Senior Member

I must admit I've never heard of the 'stick ons' that you have referred to, they sound like a pretty good idea for a nice clean surface, I might have to investigate that lot. I stuck a couple of semi flexibles on a Jayco Swift I had with Sikaflex, sticks like crazy that stuff, but apparently there is nothing on the market that will remove it. Silicon on the other hand can be removed, that's what I've heard at least. I didn't have a great power requirement, so the two small panels worked great for me.

SnowT · Guru

Gary.. if you want to go the flexible Panel's Get into Plendo's ear's for dome advice he has them and they seem to be doing the job Fine..

there are a few different method's for fixing them..
- you do not need to screw them to the Roof there are some damn good glue's/Silicone etc out that if done correctly do the job just fine..

Mind you My Panels might be sitting in a frame But They are only glued to the Frame. and I know it's going to be a Pita to replace any if they need to be..

Juergen

Brenda and Alan · Guru

Could I point out the Silicones are primarily sealants NOT adhesives and I would not use them to hold anything in place. Blues toolbox adhesive is NOT a silicone but a polymer adhesive similar to the better known sikaflex types.

Alan

dING · Senior Member

Sikaflex is the best stuff to use

Used it to stick my 20o watter

On the Landrover roof

Had a mate stick his roof rack on a bus wiv it

A few years back thought he was silly

Bbut tis still there good as new

Blue · Senior Member

Brenda and Alan wrote:
Could I point out the Silicones are primarily sealants NOT adhesives and I would not use them to hold anything in place. Blues toolbox adhesive is NOT a silicone but a polymer adhesive similar to the better known sikaflex types.
Alan

yeah, that's right, but people will still call it a "silicone" and you'll find it in the "silicone" section of your hardware store..

so I just find it easier to call it a silicone as does everyone else..

but that's why I specifically "Named" it... "Toolbox"

you can't get it wrong..

im not knocking Sikaflex, its a great product, but they have many products and I've mainly used the ones that stay a bit softer.. im guessing there's a firmer type but no one has mentioned them by name or number..

Jaahn · Guru

Hi.

I have an older Winnebago that I was going to put a couple of panels onto the roof after I purchased it. I was happy with the concept of using some corner mounts and gluing them on. I have several standard panels which I have been using for some years. smile

However I discovered that the roof had been covered with a rubber membrane type of roof. So I am reluctant to glue things to that as it too is only glued on and is very thin. disbelief Also I did not wish to put any holes into the membrane as this would compromise the integrity of the membrane ! So at this point I am still using portable panels. I guess I could put some cross bars from one edge to the other with side brackets to support them on the walls. Or I could purchase some flexible panels which may not stress the membrane if they are glued on to it over their full area. However they are very much more expensive than the panels I already have !! confuse

Any comments.

Jaahn

-- Edited by Jaahn on Wednesday 15th of October 2014 09:36:14 AM

-- Edited by Jaahn on Wednesday 15th of October 2014 09:37:31 AM