Fixing flexible solar panels to van roof

Stratman77 · Senior Member

Fixing flexible solar panels to van roof

Jaahn · Guru

Hi Chri smile

I have no experience with flexible panels as they are too expensive for my liking and you can mount ordinary panels easily with an air gap to achieve the objective to help keep them cooler. If you do not have a special reason for using flexible panels they are just too expensive compared to normal ebay panels of the same wattage, perhaps 3x to 4x more furious , so just put more cheap ones on the roof.

I am not sure why the sheeting shown would keep them cooler. I think the heat in the panel comes from the panel itself absorbing the sun heat. The tiny air chambers would not circulate much cooling air IMHO.

jaahn

PS no panel in normal use runs at or close to 25deg anywhere here in the direct sun. Perhaps in the Snowy mountains on a sunny day in winter. Or at sun-up for a short while.

-- Edited by Jaahn on Thursday 8th of June 2017 09:09:11 PM

Aus-Kiwi · Guru

Depending on the material the flexible panel is glued to . It acts as a heat sink . Yes they lose efficaincy . But can be fitted on places where hard panels cannot fit , on van angles etc ., I find unless your way up north ? Your solar should charge enough before temps get too high .

Stratman77 · Senior Member

HI, Jaahn!
Thanks for your comments. Yes, flexibles are more expensive, but I found this high quality 200 watt flexible panel on eBay:

www.ebay.com.au/itm/200W-12V-Flexible-Solar-Panel-Generator-Caravan-Camping-Power-Mono-Charging-Kit/231998159657%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D20140106155344%26meid%3Dfe71aae5820f4b7e82bb7ac7566e9960%26pid%3D100005%26rk%3D5%26rkt%3D6%26mehot%3Dpp%26sd%3D272657014205

which was under $100 more expensive than a rigid panel (around $180). I sent the specs to Derek Bester (a brilliant auto electrical engineer) from ABR-Sidewinder and he gave the flexible a very good review. I also needed an OCV of 22v max to suit my Sidewinder SDC1130D and all the rigid panels I checked were over 22v.

Springers Solar here in Brisbane (who are probably the best in Caravan solar locally) told me that all panels must have airflow between them and the roof, and they have also heard reports of serious damage if flexible panels are bonded directly to it. Yes, all panels create heat during the conversion process and the back of the panel must be spaced off the roof surface on vans and houses. The polycarbonate sheet provides an efficient insulating effect and sheets can be stacked one on top of the other and bonded together to increase the gap. Only time will tell how successful this method is.

Regards
Chris

Bagmaker · Senior Member

Seems too small for a 200w panel, are flexible ones more efficient too?
Its only about 2/3 the size of a rigid panel...............

-- Edited by Bagmaker on Thursday 8th of June 2017 11:30:31 PM

Stratman77 · Senior Member

Hi, Bagmaker!

Yes it is considerably smaller and much lighter, and I have read that they deliver efficiency ratings of up to 25%, compared to 15-18% for the rigid panels I reviewed on eBay. There is a money back warranty as well as the 25 year warranty on output. I guess we will see how good it is when it's installed.
Regards
Chris

Jaahn · Guru

Hi Chris smile

That panel may be a wonder panel but when I look at the pictures I count 48 cells in the pictures. I have never seen a 48 cell panel used for normal 12 volt charging. The panel specs seem normal but what is the picture of ?? The size seems small to me also but it may have wonder cells for a budget price confuse Reads well in the add.

Terry has had experience with flexible panels, he may wish to comment as he has fitted a lot I believe. Or you could search here for posts about them. Note a low OCV is usually achieved by having less cells than optimum for 12v charging. Normal is 36 cells low is 30 cells so I cannot see 48 cells being low ?? A puzzel that panel disbelief

Jaahn

Stratman77 · Senior Member

Hi, Jaahn!
Well, I'm expecting the panel to be delivered today by Australia Post Parcel. I will do some checking on it before I install it - just to be sure - and I'll post the results. For comparison, here is a rigid 200w panel with 36 cells:
www.ebay.com.au/itm/12V-200W-MONO-SOLAR-PANEL-HOME-GENERATOR-CARAVAN-BATTERY-CHARGING-2017-PV-MODULE-/282055049449
so I really don't know enough about individual cell performance to know why this is so.
Regards
Chris

Jaahn · Guru

Hi Chris smile

It would be interesting to see some results. And a cell count !

I always have tested my new panels out in the yard in the direct sun. All were OK more or less. If you use a resistance with some variability you can get the voltage and current at the MPP as you probably already know. The only holdup in my yard currently is a total lack of sun hmm

Good luck Jaahn

T1 Terry · Guru

These new 200w panels are a strange one and I'm yet to test one to figure out just how they are getting the output as they use the same cells as the 100w panels but they have 32 cells yet the open circuit voltage and max output voltage are the same, but the amps are double that of the 100w panel. The length is the same as the 100w panels but the actual cell width is 500mm on the 100w panel so you would expect a 200w version to be at least 1 mtr wide.....There were some 200w panels with a Vmp of around 22v that made them useless for 24v and poor output for 12v because the Vmp was too high. It is possible these are the panels in the photo and this is where the panel size comes from, it will be interesting to see just what comes out of the box.0

As far as mounting the panels, either Lexan thermoclear or the mesh stuff they use on the pretend security flyscreen doors, don't glue the panel to any of it but mount feet with 4mm studs long enough to go through the Lexan thermoclear and the solar panel eyelets and retainers big enough to stop the panel lifting off as the eyelet holes are quite large. The aim is to not restrict the free moment of the flexible panel or the Lexan as they each expand at a different rate.
As far as keeping the panel cool.... it is more a case of stopping the heat transferring through the roof by allowing the natural air currents that will be generated to move the heat away. These panels seem to react differently to heat, the Vmp drops the same as rigid panels, but the amps go up as they heat up.
These panels can climb to over 70*C on the underside so protection between them and where they mount/lay is needed so forget about throwing them up on the awning or on the fibreglass roof, the result would not be good.

T1 Terry

Stratman77 · Senior Member

Hi, Terry! Thanks for your input. I have a lifetime of experience with electrical and electronic stuff, but freely admit I know nothing about solar panels. I needed a 200w panel with a VOC max of 22v to be compatible with my dual input booster charger. All the rigid panels I checked out had a VOC of over 22v. I sent the specs to Derek Bester (an auto electrical engineer and a great bloke) who owns the ABR-Sidewinder company (I have a Sidewinder dual input booster charger) and he really gave the thumbs up to the flexible panel. This web page suggested polycarbonate as an insulating/cooling solution: itechworld.com.au/blogs/learn/mounting-flexible-solar-panels
so I have been sourcing various thicknesses of twin wall panels. I was thinking that 10mm panel might be sufficient, or is that over/underkill. What say you?
Regards
Chris

T1 Terry · Guru

Stratman77 wrote:
Hi, Terry! Thanks for your input. I have a lifetime of experience with electrical and electronic stuff, but freely admit I know nothing about solar panels. I needed a 200w panel with a VOC max of 22v to be compatible with my dual input booster charger. All the rigid panels I checked out had a VOC of over 22v. I sent the specs to Derek Bester (an auto electrical engineer and a great bloke) who owns the ABR-Sidewinder company (I have a Sidewinder dual input booster charger) and he really gave the thumbs up to the flexible panel. This web page suggested polycarbonate as an insulating/cooling solution: itechworld.com.au/blogs/learn/mounting-flexible-solar-panels
so I have been sourcing various thicknesses of twin wall panels. I was thinking that 10mm panel might be sufficient, or is that over/underkill. What say you?
Regards
Chris

Well, I'm glad someone reads my posts on the forum :lol: The material Ian from ITech world has posted is Lexan Thermoclear 10mm panelling and that works well but it expands at a different rate to the solar panel so the two can't be glued together otherwise the thermoclear tears the solar panel modules to pieces killing the panel. Learnt this bit the hard way, have had to replace 20 panels at my expense both for the replacement panels and labour as well as travelling to where the van was located as it was their mobile home while working. The free floating install method has been a winner and solved the panel destruction problem, so far so good.

Just double check the open circuit voltage with a multi meter while the panel is in full sun to make sure the voltage is lower than the required 22v and please let us know what the voltage reading is. If you have a clamp meter or a meter that will read the 12 amps that the short circuit output suggests in the specs and either plug the 2 cables together if you have a clamp meter or the black wire into the negative and red wire into the positive if it is a meter that requires the leads to be connected. A confirmation of the specs would be great so we know that either they have found a way of extracting more voltage from each module or found some strange method of wiring the modules together.... or they have got the specs wrong or the module count is wrong in the photo.

Found this one http://www.ebay.com.au/itm/200W-Flexible-Solar-Panel-Power-Battery-Mono-Charging-Caravan-Boat-Camping-12V/272657014205?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D2%26asc%3D20140106155344%26meid%3Daaeb28dd8328485ba95fe1dacb0902f2%26pid%3D100005%26rk%3D2%26rkt%3D6%26mehot%3Dpp%26sd%3D361947239482 that looks much the same and in the specs it says max voltage 18v... so is that open circuit voltage or max power voltage, don't ya just love vague specs from the seller :lol:

T1 Terry

Stratman77 · Senior Member

Hi, Terry!
Thanks so much for your advice. I can't understand why anyone would ask for help and not read member's replies! Your advice is magic as I have really done the rounds of Google (hence the ITech post) and called local 'experts' - including a top class solar company here in Brisbane called Springer Solar and they are fastidious in what they do. Not cheap, but first class work. They will NOT install flexible panels due to reports of major roof damage, unless absolved of liability. And I found no-one else who has actually done enough flexible installations - and learned the hard way what works and what doesn't. Someone on 'Everything Caravanning and Camping' Facebook page said that (here we go) he was told that 5mm Corflute worked well! I will send your install procedure to my van man who is doing the job for me. He has done dozens of rigids and some flexible installs but probably not nearly as many as yourself. One would think that an enterprising company in the solar field who has the engineering staff would design a suitable mount for flexible panels. I would certainly buy one! I intend to run 8mm cable through a 20amp auto reset breaker to the booster/charger to minimise heat and voltage drop across the roof. Once again, thanks a bunch.
Regards
Chris

macka17 · Guru

Don't know about all the technical stuff.

All I remember about Flexible panels.
is when they came out. SOME boaties swore by them.
But none gave same output as similar solid frame.
and after a few yrs.
Not too many were still being plastered all over the couchhouses.
Heat maybe????.

I've still got ONE (now)
36yr old solid BP 40w on Carport. Still outputting 2ish Amp.
of it's "guaranteed" 2.2A. or up to 85% of. for 25yrs

That's been on two Yachts bouncing around. 2 caravans.
and finished it's life with it's now ded brother. on carport floating boat battery's.

Go the solid and Personally. Don't go much over 130w for size and handling.
in a mobile environment.

I bought a 200w.. Blinked at it. and it cracked.
Brand new. never wired in.
Disposable. Plus. Next trip to dump methink's.
Can't even use one side as 6v as you could early ones.

Ordered 2 x 130w to replace. Along with old Kyocera 85w
from yacht\caravan prev.

I seriously NEVER rough handled it.
Just lifted up from one side corner to place something under. Craaaak.
Dead meat.

T1 Terry · Guru

Stratman77 wrote:
Hi, Terry!
Thanks so much for your advice. I can't understand why anyone would ask for help and not read member's replies! Your advice is magic as I have really done the rounds of Google (hence the ITech post) and called local 'experts' - including a top class solar company here in Brisbane called Springer Solar and they are fastidious in what they do. Not cheap, but first class work. They will NOT install flexible panels due to reports of major roof damage, unless absolved of liability. And I found no-one else who has actually done enough flexible installations - and learned the hard way what works and what doesn't. Someone on 'Everything Caravanning and Camping' Facebook page said that (here we go) he was told that 5mm Corflute worked well! I will send your install procedure to my van man who is doing the job for me. He has done dozens of rigids and some flexible installs but probably not nearly as many as yourself. One would think that an enterprising company in the solar field who has the engineering staff would design a suitable mount for flexible panels. I would certainly buy one! I intend to run 8mm cable through a 20amp auto reset breaker to the booster/charger to minimise heat and voltage drop across the roof. Once again, thanks a bunch.
Regards
Chris

Supplying the mounts and Lexan sheet is easy enough, if you really want them drop me a PM. It does make installation easier, punch the connector pins out of the MC4 connectors, fit their mating pins to a length of 6mm auto cable twin core so you can reach the junction block on the roof, slide heat shrink over the panel cables before plugging the pins into each other and then solder a bit of the two connector pins at the join, now slip the heat shrink over to seal off the joint. This way the connection remains solid yet easy enough to disconnect later if needed and the cable fits easily inside conduit to protect it from bird attack. Use the panel to position the feet, mark the spot with a pencil, rough it up a bit so the glue has some where to bits and wash it off with plenty of metho on a rag, let it dry, apply glue to the mounting pad and place it on the roof, put the piece of Lexan in place, slip the panel over the studs and fix the retainers on top, a used plastic milk bottle full of water as a weight to hold the feet down while the glue dries and the panel is mounted. Run the cable under the next panel in line, even through the Lexan flutes as long as the joiners stay accessible and start the process again. I even over lapped the panels with the top over or under the bottom of the next panel depending on the direction of the slope and airflow to avoid making a funnel, here is a photo of one I prepared earlier

1900w semi flexible solar completed job small.jpg

T1 Terry

Stratman77 · Senior Member

Hi, Terry! Thanks a bunch for your help. I'm confident now that I know how to install my panel without problems down the track. You have really gone the extra mile, and I hope some day I may be able to do the same for you in return. Once again, thanks for your time. Regards Chris

mr glassies · Guru

Hi Chris have you done any tests on those panels yet I'm keen .

Dibs

Stratman77 · Senior Member

Hi, Graeme!
My van man extraordinaire is installing the panel right now. He was very impressed with the preliminary tests he always does before installation. We will be going on a 4 night freecamp at Bestbrook next week, so I'll let you know.
Regards
Chris

Jaahn · Guru

Hi Chris smile

I am all agog for some feed back on your wonder panels. Please confuse

Jaahn

Stratman77 · Senior Member

Hi, All!
Just to let you know that the panel works very well. I was camped in partial shade with only about 2 hrs of direct sun, but it still managed to bring the aux battery back up each day. I'm pretty impressed.
Regards
Chris

CC Bear · Senior Member

I will carry on with this thread instead of starting another as it will keep the information together. I am looking for help on the flexable panel I have for the van. I intend to mount it in a similiar fashon to what Terry has suggested using aluminium rectangular section across the van and bolt through theses the thermo sheet and the panels.

So what I would like to knowis this panel ok to use As the van has a 12 v system.

This is the controller mounted near the 110 amp calcium battery and feed by a anderson plug on the A frame which will go to the solar panel on the roof.

Any advise would be appreciated, cheers

Bagmaker · Senior Member

Not with that regulator, the panel voltage is too high. You would have to use a true MPPT regulator

Jaahn · Guru

Hi CC Bear smile

You know I never think tacking onto another thread is a good idea. Just start another one and there is usually much less confusion aww

That panel is a bit unusual as it has a higher voltage but not high enough for a 24V panel. It must have an odd number of cells ?? However it will work, but you will not get the full output ? The maximum possible will be about 120 Watts with that simple regulator. You might also like to check that that regulator will handle the 28.5 volt input too in its specs.

As Bagmaker has alluded, you will get a better result with a true MPPT regulator. This will get the best output from the panel possible. However as said in another thread there are plenty of cheap fakes hmm . Read this other thread for more information as it has been discussed ; http://thegreynomads.activeboard.com/t63725690/can-i-use-this-panel-on-my-motorhome/

Jaahn

T1 Terry · Guru

Be very careful not to link the panels in series if you do go for an MPPT controller, those panels can not handle the series voltage without blocking diodes on each panel to prevent back current frying the circuits under the cell modules themselves. Those diodes under the terminal strip are designed to allow half the panel to charge if the other half is shaded, they are not by pass diodes as such so not designed for series panel connection and certainly not blocking diodes.
These semi flexible panels are built some what differently to the rigid panels so care must be taken not to subject the panels to back current or failures can occur.
After all that, those panels may not give you great current output using a PWM controller, but they will not suffer enough voltage drop in the summer sun to cause the well known "batteries don't reach the end of boost voltage in the middle of summer" problem. This is more an issue with flooded cell batteries that need to reach 14.8v for the end of boost and 16.5v for an equalising charge, hot 12v panels with Vmp of 17v @ 25*C are struggling to get over 14.6v in the harsh summer sun.

T1 Terry

CC Bear · Senior Member

Hi Terry will only be the one panel, would I need a 20 or 30 amp mppt controler

Stratman77 · Senior Member

Hi, Robert! I would strongly suggest you take Terry's advice as he is really qualified in this field. Regards Chris

Jaahn · Guru

CC Bear wrote:
Hi Terry will only be the one panel, would I need a 20 or 30 amp mppt controler

Hi Bear smile

You are asking the only person on here who does not believe in MPPT controllers and actively denies they work ?? Your choice. ! confuse

I would say the 20 A one would be OK but I suggested you read the other thread I referenced for more information or you will end up with a fake unit which does not work as MPPT.

Terry I have never had a LA battery which needed "16.5v for an equalising charge". Saying such dis-information does you no good IMHO.

Jaahn

T1 Terry · Guru

If you really want to use that panel then an MPPT controller would be the way to go, but one that really is an MPPT controller and not just labelled as one for sales purposes.
Seriously though, you would be far better off input current (amps) wise, $$ wise and panel space wise to get a few 100w semi flexible panels with a Vmp around the 17v mark and run them through the controller you already have rather than buying a new controller and that mis-matched voltage panel.

T1 Terry

T1 Terry · Guru

Jaahn wrote:
CC Bear wrote:
Hi Terry will only be the one panel, would I need a 20 or 30 amp mppt controler
Hi Bear
You are asking the only person on here who does not believe in MPPT controllers and actively denies they work ?? Your choice. !
I would say the 20 A one would be OK but I suggested you read the other thread I referenced for more information or you will end up with a fake unit which does not work as MPPT.
Terry I have never had a LA battery which needed "16.5v for an equalising charge". Saying such dis-information does you no good IMHO.
Jaahn

Maybe a read through the major flooded cell battery manufactures literature might help, this higher voltage is required for equalisation, some sulphated plate surface shedding and stirring of the electrolyte to get rid of the stratified electrolyte problem that topping up regularly with water causes. Basically, the fix for under charged batteries that don't a return to 100% SOC every cycle and have either a far too short or to low voltage absorption cycle programmed into the charger.

One of those things learnt working with electric vehicles in the days before lithium batteries.

T1 Terry

Jaahn · Guru

T1 Terry wrote:
Terry I have never had a LA battery which needed "16.5v for an equalising charge". Saying such dis-information does you no good IMHO.
Jaahn
Maybe a read through the major flooded cell battery manufactures literature might help, this higher voltage is required for equalisation, some sulphated plate surface shedding and stirring of the electrolyte to get rid of the stratified electrolyte problem that topping up regularly with water causes. Basically, the fix for under charged batteries that don't a return to 100% SOC every cycle and have either a far too short or to low voltage absorption cycle programmed into the charger.
One of those things learnt working with electric vehicles in the days before lithium batteries.
Terry

Hi Terry smile

If some rare person is running an electric vehicle with flooded cells off their caravan solar system I would presume they had enough expertise to Know all the facts.

The rest of the normal people out there are most likely running AGM batteries or possibly gel which do not require or need equalising charges or very high charge voltages. If they have flooded cells then they could write in and tell us what the manufacturers recommendation is for Voltages. hmm

My home sealed batteries specify max 2.38V per cell = 14.28V for 12v system.

Jaahn