flexible vs rigid solar panels output

**prelude** · 10th May 2022, 09:58 PM

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** · 11th May 2022, 01:43 AM

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.

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Cheers
simon

**prelude** · 15th May 2022, 08:49 PM

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** · 16th May 2022, 10:13 AM

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** · 16th May 2022, 10:15 AM

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** · 18th May 2022, 04:47 PM

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** · 18th May 2022, 05:42 PM

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.

**trout1105** · 18th May 2022, 05:46 PM

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.

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

**gusthedog** · 18th May 2022, 08:04 PM

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** · 19th May 2022, 02:47 AM

Originally Posted by 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.

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

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