flexible vs rigid solar panels output

[prelude]

I have been using a rigid 100watt amazon cheap solar panel for testing for about 2 years now. I have a pretty good idea what a panel like that can do under different circumstances coupled to a 100Ah gel battery running a national luna fridge.

Now that I am getting closer to fitting out my rig for full time travel I find that I need more than one panel at least. Rigid panels weigh anywhere between 7-8 kilo's per 100 watt panel. A flexible panel (from a reputable brand) can weigh as little as 1.9 let's say 2kg. This means I can have 4 times the amount of solar panels on my roof for the same weight... That is significant since weight is the most important thing on any rig (mine was already overweight so I have to cut here and there).

I know there are pro's and con's to flexible panels but I can't find any real test data on let's say output other than broad claims. ie. a flexible panel get's hotter since it can not cool (often they are mounted flush on a roof) but how much hotter they get or how much output is lost that way is never really touched upon.

Allow me to put things into perspective: I have a CTEK D250SE where I would connect the panels to. I know that they can only handle 300watt's of input but that is a moot point since you can hook up way more than that, the system simply won't charge more than 20 amps. With only 1 panel and an overcast day I would get 1-2 amps of charge, with 4 panels I would still get 4-8. I also know that longevity of flexible is a bit of a thing but I reckon that if I can get 5 years out of the panels it should be fine. The thing I do not know is how hot DO those buggers get and what does that mean in terms of output?

So, does anyone here have any performance comparison experience / data laying around?

Cheers,
-P

[simonmelb]

I only know mine works to spec putting out a true 100w as tested not in hot weather.

It is one of the only flexible panels on the CEC approved list so is independently tested.

No idea about hot weather performance but I believe you mount it on a core flute type backing to allow cooling - plenty of those blue core flutes around that need pulling down and put to good use.

178693178694

Got it here: Off Grid Solar Panels - Enjoy the Great Outdoors & Stay Connected (https://www.solar4rvs.com.au/solar-panels/?cn=824&rf=cn)

Cheers
simon

[prelude]

Thanks Simon,

Cooling is indeed important and I am considering creating two channels to slide the panels into (alu profiles) that will also lift them ever so slightly of the roof and create an airgap. The added benefit of this would be that I can pull one or two out and use them as "blankets" effectively and increase solar power production when stationary in the shade.

Not sure about the durability of the "flexible" panels though...

Cheers,
-P

[W&KO]

We find 3 semi flex panels on the defer……

it’s our 3rd set over five years.

I probably should count the first set of 2 as they were just cheap rubbish……

2nd set of 2 performed pretty good although the material they were made from was looking worse for wear, cloudy and cracking. For the price I would have brought them again but they don’t appear to be made anymore.

Current set off 3 x 120’s are doing OK. One panel is shielded by a bag on the roof…..generally see low to mid 200’s every day.

[W&KO]

Whoops, meant to add…

Semi flex panel don’t like being used as portable panels……we found this out with the first set….although they were a budget set.

My take is they don’t like to be flexed all the time, flex once to where they are mounted

[prelude]

Interresting.. I would of course take care not to bend them but since they are flexible the will bend on their own weight.

I do intend to mount the flexible panels in a fairly rigid setup on an absolutely flat roof, sliding them inside a set of alu profiles so I would not ever have to mount them bended. I could see if I could make the system such that I take them off with the alu to keep them from bending but then I would make them heavier almost negating the advantage of lighter panels to begin with.

Do you reckon that the panels wear more quickly due to rattling? I mean, even if the sides are properly mounted down, the middle of the panel can flex somewhat and bounce up and down due to corrugations.

Cheers,
-P

[trout1105]

We have just bought a vintage 15 foot pop up van that I am in the process of refurbishing.
I will be installing 2x 250w ridged panels on tbe roof mounted so that there is plenty of air flow under them to keep them cool.
I have tried the flexible panels and they Suck when they get warm/hot.[thumbsupbig]

[trout1105]

We have just bought a vintage 15 foot pop up van that I am in the process of refurbishing.
I will be installing 2x 250w ridged panels on tbe roof mounted so that there is plenty of air flow under them to keep them cool.
I have tried the flexible panels and they Suck when they get warm/hot.[thumbsupbig]

The flexible panels Do work But a well mounted ridged panel of the same wattage will out perform the flexible panel easily [biggrin]

[gusthedog]

How big is your fridge? I run all the lights in my van and a 38 litre arb fridge and have a 12 year old but good quality 60 watt solid panel and controller mounted permanently on the rhino bars that feeds my second battery, an 80ah deep cycle. I have another 60w panel to piggy back if I need it but I've never run out of power.

My two 60watt panels and controller set me back $800 or so. Could it simply be that a better quality system of a smaller size would do you?

I haven't measured the output of my panels but my single 60watt Japanese panel copes with my stuff easily. A mate with a supposed 240w system struggles with about the same load. His is a Kings system which are known to be ****e quality though.

[trout1105]

How big is your fridge? I run all the lights in my van and a 38 litre arb fridge and have a 12 year old but good quality 60 watt solid panel and controller mounted permanently on the rhino bars that feeds my second battery, an 80ah deep cycle. I have another 60w panel to piggy back if I need it but I've never run out of power.

My two 60watt panels and controller set me back $800 or so. Could it simply be that a better quality system of a smaller size would do you?

I haven't measured the output of my panels but my single 60watt Japanese panel copes with my stuff easily. A mate with a supposed 240w system struggles with about the same load. His is a Kings system which are known to be ****e quality though.

The van has a 90l 240v fridge in it that is in pretty good nick so I am not chucking it out, It also has a small air con in it that I will be replacing because when I started it up the other day it blew the arse out of the compressor.
To run the fridge and the air con I will need to run them via an inverter hence the 500w of panels which only weigh about 20kg when fitted and lets face it you can Never have enough solar power and if you have enough room to fit the extra wattage Why not.
The solar will charge 2x 115AH AGM batteries via a 50A MPPT controller which will feed the 3kva inverter and the other 12v stuff in the van
including another 38l Engel.

Even with this much available power I won't be able to run the air con for too long But the fridges it should be fine[thumbsupbig]

[prelude]

Admittedly I should think a single 100watt solar panel is enough for all my touring needs under normal circumstances. I run a 50L national luna twin weekender (so it has a fridge and freezer in one) which is fairly frugal. The 100watt solar is connected through the MPPT of my CTEK and that is hooked up to a 90Ah gel battery.

The thing is though. I have been testing this setup, stationary, in the backyard to see what it does under different circumstances. Under cloudy but hot conditions the battery does run down eventually but it goes down very slowly. When driving the smartpass pushes a lot of power into the battery all at once, if it is drained enough to accept a high charge but like trout I have been eyeballing an AC to bring some relief during extreme conditions (45c in india for example...)

I had to start somewhere in my research and the first thing that came up of course is generating power, let alone storing it.

Thus far it seems that:

decent brand panels seem to fare a lot better in terms of aging, though 5 years is about what you can expect from them.
prevent bending, they are meant to be bent into a shape once and not for permanent bending
keep em cool (enough) to do their job (and prevent premature wear)


all those are acceptable for me, except the bending part. I would like to be able to move one or two into the sun if needed so that requires some more thought.

-P

[trout1105]

In cooler weather a 100w panel MAY run a smaller fridge But once you get above 30C the fridge will draw more power than a 100w panel can produce, At 45C the fridge will shut itself down pretty fast because the battery is severely depleted which isn't good for the lifespan of the battery.
As far as trying to run an AC in 45C temps with only 100w input, Forget that idea.[thumbsupbig]

[prelude]

Trout mate :)

I know, an AC with 100watts is AT MOST 300 watts of cooling power... Nah. I guess I'll make a new topic about AC in the relevant forum. However, at very high temps the fridge still works a charm (can't touch the metal casing since it is too hot) but the solar panel can keep up. I unfortunately have no datalogger screenshots but to my surprise the NL is really very good at this sort of work. It runs at around 3-4 amps when running, it just needs to kick in more often but I still had a net gain with an internal temp (of the closed vehicle) of over 50c. Sure, my battery was nearly charged (around 96% so it could not accept a high charge current but I still got it to 100% by the end of the day. Pretty happy with that!

In any case, I guess flexible solars are a go if you: have enough space to mount them (cooling) and do not bend them more than once. Here is hoping... :)

Cheers,
-P

[DiscoMick]

Our Jawa caravan came new with 300 watts of flexible solar panels on the roof, but I see Jawa has now moved to standard glass panels instead.
Reason seems to be the flexible panels were stuck on the roof and so there was no airflow for cooling in hot weather, which reduced their lifespan.
Ours are still working fine, but if the performance drops off we'll go glass.
The replacement cost is not just the panels, but the wiring also has to be changed.
Meanwhile we carry both a 200 watt folding glass panel and a generator, rarely used, as backups.

[Tombie]

As I posted before - i removed 400w of high end flexible panels and fitted 2x 115w Victron rigids.
I'm producing more than I was before hand, and quicker.

Especially when its warm.

[trout1105]

Our Jawa caravan came new with 300 watts of flexible solar panels on the roof, but I see Jawa has now moved to standard glass panels instead.
Reason seems to be the flexible panels were stuck on the roof and so there was no airflow for cooling in hot weather, which reduced their lifespan.
Ours are still working fine, but if the performance drops off we'll go glass.
The replacement cost is not just the panels, but the wiring also has to be changed.
Meanwhile we carry both a 200 watt folding glass panel and a generator, rarely used, as backups.

Why would you have to replace the existing wiring as you would only be replacing the panels Not the entire system?

[Bazzle218]

Im sure that all the panels mentioned work fine but are rather expensive. I have been running a 230 watt panel for 2 years which charges two 100amp hour lithium, which in turn run two Engels one as a full time freezer and the other as a fridge. Obviously with the correct controller. The panel cost me the princely sum of $20. Old house panels are cheap as chips and as long as you check them with a multi meter you have no issues. I also provide a stand off with rubber bushes. Panel is mounted to my 130 fiberglass canopy. Baz

[W&KO]

Interesting observation today…..

We’ve had a sudden change of location….Broome to Perth over a couple of days….

The semi flex panels are performing much better down here in the cooler weather.

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