Any experiences with ebay flexible panels

[PhilipA]

For the last 5 years I have used a 120W folding solar panel with a GSL 12amp MPPT controller near the battery with 6 SWG 20metre cables. This has reliably provided up to 6.5 amps even at 9-10AM oriented to the sun on my inline ABR amp/watt/volt meter..

However the 120W folding panel is very bulky and heavy so I looked for a lighter alternative and bought a 150Watt flexible panel from Ebay , so that I could lay it on the bed of my hard floor camper and save storage room underneath and weight.

Well , the first time I got to use it last weekend gave a cold amp reading of 2.1 amps , which deteriorated to 1.45 amps when the panel got hot. The whole setup was otherwise the same ie MPPT controller , same battery , same amp meter.

To say I was not impressed is an understatement resulting in my currently taking action to return the panel. I don't know if there is something wrong with the panel or that is all you get. I have seen other comments in reviews which suggest that the real output is much less than stated . But 8+amps stated spec vs 2actual? Come on.

Has anyone had experience with 150-200watt flexible panels as advertised on ebay? Seeing I have a 12 amp MPPT controller I might as well go as near to that as possible and based on review comments they are not outputting anything like the stated output.

I would be interested in what actual amps is available from which brand of flexible panel from which seller.
Appreciate any help .
Regards Philip A

[Tombie]

I’m using 2x 100w flexible panels.

1 is working fine - does about 5a in good sun..

1 is playing up - unsure if it’s wiring or panel (haven’t had the time yet)

[weeds]

I purchase 2 x 100w fexible panels from vic off road........in parallel they only got to about 30% of what they were rated at, I than tried one by itself and was lightly better....I now run them in series and they perform around 50-60%

I have since purchased one 100w flexible panel from Springers Low Voltage...it performs as it should....although was 3 x times the price.

I'm considering switching to the flexible folding jobbies that fold up to brief case size.......they seem to get better reviews.

[DiscoMick]

No experience with folding panels, but I did find some interesting information in these:

Facts you MUST know before buying lightweight flexible solar panels for your caravan or boat (https://www.solar4rvs.com.au/buying/buyer-guides/choosing-flexible-solar-panels/comparison-of-good-and-bad-lightweight-flexible-so/)

Problems With Flexible Solar Panels - Best Solar Tech (https://www.bestsolartech.com/problems-flexible-solar-panels/)

[PhilipA]

The selling company has now given me a refund so at least I am not out of pocket for the experience.(except that the company although listing in Australia and having Australian stock in Sydney was actually based in California so I was charged an international transaction fee)

Regards Philip A

[weeds]

The selling company has now given me a refund so at least I am not out of pocket for the experience.(except that the company although listing in Australia and having Australian stock in Sydney was actually based in California so I was charged an international transaction fee)

Regards Philip A

I didn't have any luck with vic off road although there panels do say do not connect in parallel or series.....

[weeds]

I have since purchased one 100w flexible panel from Springers Low Voltage...it performs as it should....although was 3 x times the price.

.

pretty sure they are branded Scorpion .... if that helps

[PhilipA]

I just looked at a site which lists all of the Chinese Tier1 solar panel producers. Guess what , not one makes a flexible panel or a rigid panel under 275 watts which are probably real watts.

I am now in a bit of a quandary. Do I buy a 240watt panel which may only give say 8 amps or may give the listed 13 amps which is over the capacity of my MPPT controller.

Or maybe buy a 200 watt which is listed as 11. something just inside my MPPT but may only give about 6 amps or less than my current folding panel.
The company listed by Disco Mick sells a 200 watt panel at about $800!
Agggh What a minefield.
It seems to me that almost all of reviewers on various sites really have no idea what the output of their panels actually is. And they wonder why people have flat batteries.
Regards Philip A

[weeds]

I just looked at a site which lists all of the Chinese Tier1 solar panel producers. Guess what , not one makes a flexible panel or a rigid panel under 275 watts which are probably real watts.

I am now in a bit of a quandary. Do I buy a 240watt panel which may only give say 8 amps or may give the listed 13 amps which is over the capacity of my MPPT controller.

Or maybe buy a 200 watt which is listed as 11. something just inside my MPPT but may only give about 6 amps or less than my current folding panel.
The company listed by Disco Mick sells a 200 watt panel at about $800!
Agggh What a minefield.
It seems to me that almost all of reviewers on various sites really have no idea what the output of their panels actually is. And they wonder why people have flat batteries.
Regards Philip A

I’ll be buying a second scorpion. This gives me 2 x 100 panels which will slip under the bed or if the bride wins be mounted on the roof rack.

I current have the three flexible on the roof rack.

[Ferret]

..It seems to me that almost all of reviewers on various sites really have no idea what the output of their panels actually is.

I believe the panel's rated output is determined by a standard which does not match real world conditions very well.

If a panel is rated @ 100W under the standard test you will probably get ~75% of that rating around mid day (ie at best).

[DiscoMick]

I read that Sun Power doesn't make flexible panels of more than about 150 watts, I think it was. It is the major Chinese manufacturer. Might be better to buy 2 x 100 watts than try to buy a single larger panel.
I mostly bought 80 watt fixed panels.

[AK83]

....

I am now in a bit of a quandary. Do I buy a 240watt panel which may only give say 8 amps or may give the listed 13 amps which is over the capacity of my MPPT controller.

....

Hopefully someone else will chime in here too, BUT!! I'm sure you can input more amps into the charge controller than it's rated spec, just that if you do input more amps, you just don't get those amps out.

So if you had 13amps at any point into your 10 amp controller, you won't damage anything, it just limits current to 10 amps out(discounting any losses here for simplicity).

What you can't do tho is input more voltage than the prescribed open circuit voltage rating on the controller!

That is, if you had multiple panels and wanted to do multiple connected panels for more volts/current, then you wouldn't run them in series as it will increase voltage .. and possibly kill the MPPT.
But, if you did so in parallel, then you maintain the voltage(22v or whatever) but have access to more current in an ideal situation.

I think the idea is that if you run the panels in parallel, then in less than ideal conditions, you still get good current anyhow.
This second notion is similar to your idea of getting a 240w panel .. it'll still be 22voc, but will give you your 13amps .. same as two 120w panels will.

.. anyhow! that's the way I taught myself to understand it all just by reading bits all over the place. Of course I may have it totally wrong.

Which MPPT controller do you have .. could help someone with more knowledge to offer better insight.

[weeds]

Hopefully someone else will chime in here too, BUT!! I'm sure you can input more amps into the charge controller than it's rated spec, just that if you do input more amps, you just don't get those amps out.

So if you had 13amps at any point into your 10 amp controller, you won't damage anything, it just limits current to 10 amps out(discounting any losses here for simplicity).

What you can't do tho is input more voltage than the prescribed open circuit voltage rating on the controller!

That is, if you had multiple panels and wanted to do multiple connected panels for more volts/current, then you wouldn't run them in series as it will increase voltage .. and possibly kill the MPPT.
But, if you did so in parallel, then you maintain the voltage(22v or whatever) but have access to more current in an ideal situation.

I think the idea is that if you run the panels in parallel, then in less than ideal conditions, you still get good current anyhow.
This second notion is similar to your idea of getting a 240w panel .. it'll still be 22voc, but will give you your 13amps .. same as two 120w panels will.

.. anyhow! that's the way I taught myself to understand it all just by reading bits all over the place. Of course I may have it totally wrong.

Which MPPT controller do you have .. could help someone with more knowledge to offer better insight.

I run a Victron 75/15 75v/15amp.....given I have two massively under performing panels and one performing near its rated output over all I’m under

[PhilipA]

Which MPPT controller do you have .. could help someone with more knowledge to offer better insight.






I have a GSL 12-1 which is capable of 12 amps but also can handle two panels in series. You connect to the battery first and it works out whether to charge at 14 volts or 28 volts.These are well regarded Australian Made? real MPPT controllers.

Up until now I have run my 120Watt folding panel in series and it gives up to 7amps measured by my ABR inline meter, but usually 6.5 amps which AFAIK is very good for a 120Watt panel.
That is why I was gobsmacked with the 2.1 amps out of the supposed 150Watt panel.

I think that there was something wrong with the panel as it was split into 2 circuits in parallel and one gave 20.7 volts no load and the other only gave 10.4. There were three terminals of which 2 were positive into the positive lead.

Regards Philip A
But I am tired of the ****fight when the panels don't perform. I spent lots of time , took photos, answered 25+ emails , to be told at one stage that an "expert" said 2amps was normal! from a 150watt panel. Amazon have 100watt panels from Allpowers which seem to be OK , but the youtube review is by some dumb yank who talks about volts not amps.

[Bigbjorn]

Over twenty years ago I was in the US during early winter.I noticed many of the cars parked at bus and train stations had flexible solar panels sitting on the dashboard. These were sold at all the auto parts shops like Champion Auto Store. You rolled them up like a newspaper and put in the glove box when not in use. Batteries don't like the very low temperatures in the snow belt (neither do I) so commuters used these things. No idea of their output but they were very popular. Friends in Omaha didn't have a heated garage but they plugged their cars in to block heaters and trickle chargers at home.

[nick_e]

I have zero experience with these portable solar panels, but if they are anything like the smaller ones you can use on electronic projects like solar garden lights, then flexible isn't a good idea if they are going to be moved around a lot, especially in cheaper panels. They are very prone to internal damage where the cells are connected together.

[PhilipA]

After I got my refund from the first seller, I saw a demo semi flexible 150W panel on ebay for $180.

I had previously called GSL and talked to a very helpful "nerd" who advised/explained that 150W was the largest panel my 12-1 GSL MPPT could handle, as if the voltage of the battery was at say 12volts , then the current would increase to 12 and a bit amps.

The panel is a monster with 48 cells and is about 1.5 x 1.2 metres.

I tested it out in my conditions at home, and there is nowhere I can get full sun. However with a tree trunk and some leaves blocking a full line of cells plus another 5 or 6, I was getting 2.5 amps. This is in my experience a good output.

The Voc is 29Volts!( measured ) while the vendor reckons Vmp is 22volts So the GSL MPPT will love it and I should get at least 8 amps.
The vendor fibbed a bit saying it had only been used one hour as a demo, as it had obviously been mounted by marks on the screw holes on it and one eyelet missing.

BUT remember my motivation is to save weight in my camper trailer and to be able to lie it flat on the bed. I have made legs out of 3MMx20MM aluminium strap, and at least in the cool it doesn't sag. I can always brace it with a bit of strap if necessary.
I am happy with my purchase.
Regards Philip A

[Tombie]

Hey if it works for you (and it’s safe) that’s all that matters.

I recently finished the solar and charging set up on our Xplorer and it’s the single best thing I’ve done to it.

No more concerns about power reserves, it’s overcast as heck today and there’s no issue at all.

[DeanoH]

Reading this thread it seems to me that what is totally misunderstood here (again) is the basic electrical fact that current is taken not given. The amount of current taken in a solar battery charging scenario is determined by the voltage supplied by the solar regulator and the state of charge (SOC) of the battery ie. load. The amount of current taken is not a definitive measure of the capacity of the charger or solar panel(s). If the battery is fully charged (ie. no load) then the current flow will be minimal and if the battery is flat the charging current will be greater but may not be an accurate measure of the system capacity.

There is one way and one way only to measure the output of a solar panel.

1/. Place the solar panel to be tested in full sunlight perpendicular to the sun.

2/. With no load on the panel measure the open circuit voltage (Voc) of the panel. This should be the same as the stated Voc in the sticker on the back of the panel.

3/. Using an ammeter with a capacity that is greater than the short circuit current (Isc) given on the back of the panel place the ammeter probes on the output terminals of the solar panel. This may seem a bit drastic as doing this to any other generating source will result in much spark, flame, smoke etc but this is how you measure Isc of a solar panel.

Solar systems are about generating power and transferring that power to a battery or other load. The voltages and currents between the panel and solar reg are not constant, they vary depending on a number of circumstances and equipment types. What is important is the generation and transfer of power from the panel to the battery (load).

To really test out your solar setup try doing something like this. :)

1/. Connect a fully charged battery to your solar reg.

2/. Set up your panel(s) in good direct sunlight and connect to solar reg.

3/. Connect a load to the battery/solar reg that is equal to or slightly greater (measured in watts) than the output of the panels (also measured in watts). Headlights/driving lights are good for this.
note. if the load is fed via the reg as in the OP's case don't exceed the regs maximum current specs.

Measuring the output voltage and current from the panels (and multiplying the figures together) will give you the real world maximum power (in watts) your system is capable off generating. IMO if you achieve 80% of what the panels are rated at you're doing very well.

Again, solar systems are about the generating and transfer of power (measured in watts). Values of voltage and current can vary greatly especially between the panels and the reg and don't give a true indication of the capabilitys/performance of the system. :)

Deano :)

[Dorian]

I was trying to grasp why solar panels don't try to put out a constant wattage. Here is a short and sweet article that I found.

Solar Panel Specifications Explained – KG4CYX (https://www.kg4cyx.net/solar-panel-specifications-explained/)

It appears to me that the most important number for a solar cell is Vmp (Voltage, max power) and if your charging batteries, it needs to be around 14-15 Volts.

Cheers Glen

[DiscoMick]

Useful article - thanks for posting it.
I'm a novice at this electrickery, but as I understand it, put very simply, the output varies so regulators limit it, often to 10 amps, which batteries can easily handle.

[bee utey]

Useful article - thanks for posting it.
I'm a novice at this electrickery, but as I understand it, put very simply, the output varies so regulators limit it, often to 10 amps, which batteries can easily handle.

The output of a regulator depends mainly on two things, the amount of input current/voltage available (from the panel/s in the sun) and the size of the electrical load. The load may be a discharged battery, a nearly fully charged battery, or a battery system with a load, e.g.a fridge. It has no way of reading the label on a battery that might recommend limiting input current, as placed on some AGM batteries. If you attempt to put more power into a solar regulator than it is designed to handle, it will either 1. blow a fuse, 2. emit smoke or 3. intelligently limit currents to a pre programmed level, if it is expensive enough. As Drivesafe frequently points out, an automotive battery can usually handle shed loads more current than the 10 amps a small panel set puts out, like from an alternator. It's voltage that requires the most control, not amps.

[Ferret]

...It appears to me that the most important number for a solar cell is Vmp (Voltage, max power) and if your charging batteries, it needs to be around 14-15 Volts.

I think you might be miss understand what the article says a bit.

Vmp is the panel voltage at which your panel puts out it's maximum power. For the most efficient operation of your panel you need to keep your panel voltage as close as possible to Vmp regardless of what the Vmp of the panel actually is.

Of course Vmp must be a least 14- 15 volts if your going to charge a battery but it's not a problem if it is higher than that for battery charging purposes.

If Vmp of your panel is actually 20V then fine, your panel will be producing power at it's maximum possible potential for the current sunlight conditions if it is being allowed to operated at 20V. Note, it's maximum potential is not the same as it's rated power output.

Now you can't charge a battery at 20V so you need something to drop the voltage supplied to battery to ~14V. This is the job of the regulator, either a PWM or a MPPT regulator.

The PWM regulator drops the voltage to ~14V by lowering the panel voltage to ~14V. Since the panel is no longer operating at Vmp some of it's potential is being wasted.

The MPPT regulator drops the voltage to ~14V by converting excess voltage from the panel (over and above the ~14V required to charge the battery) into current. The panel voltage is held at Vmp. Since the panel voltage is held at Vmp the full potential of the panel is always available.

So a Vmp of 14 - 15 V is not necessarily the most important thing when charging batteries. It just needs to be a least 14 - 15 volts. If Vmp is very much higher than 14 - 15 volts then all the better - provided you use an MPPT regulator. If Vmp is very close to 14 - 15 volts then great - just use a cheap PWM regulator and you won't be any worse off.




...I'm a novice at this electrickery, but as I understand it, put very simply, the output varies so regulators limit it, often to 10 amps, which batteries can easily handle.

No regulators don't regulate current, they regulate voltage.

[Dorian]

I think you might be miss understand what the article says a bit.


The MPPT regulator drops the voltage to ~14V by converting excess voltage from the panel (over and above the ~14V required to charge the battery) into current. The panel voltage is held at Vmp. Since the panel voltage is held at Vmp the full potential of the panel is always available.

So a Vmp of 14 - 15 V is not necessarily the most important thing when charging batteries. It just needs to be a least 14 - 15 volts. If Vmp very much higher than 14 - 15 volts then all the better - provided you use an MPPT regulator. If Vmp is very close to 14 - 15 volts then great - just use a cheap PWM regulator and you won't be any worse off.


No regulators don't regulate current, they regulate voltage.

140362


I understand what you are saying, however if you are charging a 100Ah house battery that's dropped down to say 11.2V then the battery will quite happily draw 20 + amps, which is 200 + watts. And this is probably when you need every bit of amps you can get, if the regulator is happy to output 12 amps say, and the panel is only capable of 6 amps at Vmp, it's going to let the solar panel drop down to battery voltage which will reduce it amps output (blue line).

I was surprised with this revelation as I always thought that as the load voltage dropped the amperage would increase to keep the wattage constant as every other electrical thing on the planet does.

Cheers Glen

[bee utey]

140362


I understand what you are saying, however if you are charging a 100Ah house battery that's dropped down to say 11.2V then the battery will quite happily draw 20 + amps, which is 200 + watts. And this is probably when you need every bit of amps you can get, if the regulator is happy to output 12 amps say, and the panel is only capable of 6 amps at Vmp, it's going to let the solar panel drop down to battery voltage which will reduce it amps output (blue line).

I was surprised with this revelation as I always thought that as the load voltage dropped the amperage would increase to keep the wattage constant as every other electrical thing on the planet does.

Cheers Glen

Regardless of what your battery 'wants", a MPPT solar regulator will deliver no more volts x amps than your panel V mp x A mp, less around 5% to 10% lost power. So an available 6A at 17V mp from the panel (~100W) will deliver no more than 8A at 12V (~95W) or thereabouts to the battery.

[Ferret]

140362


I understand what you are saying, however if you are charging a 100Ah house battery that's dropped down to say 11.2V then the battery will quite happily draw 20 + amps, which is 200 + watts. And this is probably when you need every bit of amps you can get, if the regulator is happy to output 12 amps say, and the panel is only capable of 6 amps at Vmp, it's going to let the solar panel drop down to battery voltage which will reduce it amps output (blue line).

I was surprised with this revelation as I always thought that as the load voltage dropped the amperage would increase to keep the wattage constant as every other electrical thing on the planet does.

Cheers Glen

Maybe I don't understand exactly what you're trying to say but I think you should watch this video.

YouTube (https://www.youtube.com/watch?v=wmyuxKmlBCk)

In particular when they start explaining things about high / low charged batteries and current around 4:30 mins into the video

[DiscoMick]

I think you might be miss understand what the article says a bit.

Vmp is the panel voltage at which your panel puts out it's maximum power. For the most efficient operation of your panel you need to keep your panel voltage as close as possible to Vmp regardless of what the Vmp of the panel actually is.

Of course Vmp must be a least 14- 15 volts if your going to charge a battery but it's not a problem if it is higher than that for battery charging purposes.

If Vmp of your panel is actually 20V then fine, your panel will be producing power at it's maximum possible potential for the current sunlight conditions if it is being allowed to operated at 20V. Note, it's maximum potential is not the same as it's rated power output.

Now you can't charge a battery at 20V so you need something to drop the voltage supplied to battery to ~14V. This is the job of the regulator, either a PWM or a MPPT regulator.

The PWM regulator drops the voltage to ~14V by lowering the panel voltage to ~14V. Since the panel is no longer operating at Vmp some of it's potential is being wasted.

The MPPT regulator drops the voltage to ~14V by converting excess voltage from the panel (over and above the ~14V required to charge the battery) into current. The panel voltage is held at Vmp. Since the panel voltage is held at Vmp the full potential of the panel is always available.

So a Vmp of 14 - 15 V is not necessarily the most important thing when charging batteries. It just needs to be a least 14 - 15 volts. If Vmp very much higher than 14 - 15 volts then all the better - provided you use an MPPT regulator. If Vmp is very close to 14 - 15 volts then great - just use a cheap PWM regulator and you won't be any worse off.





No regulators don't regulate current, they regulate voltage.I'm sure you're right. All mine say 10A.

[PhilipA]

It just needs to be a least 14 - 15 volts. If Vmp very much higher than 14 - 15 volts then all the better - provided you use an MPPT regulator. If Vmp is very close to 14 - 15 volts then great - just use a cheap PWM regulator and you won't be any worse off.

Yes GSL state that to work efficiently , their MPPT regulators need at least 4-4.5 volts above max regulated ie about 18.5 volts Vmp. The regulators like a higher Vmp and gain a little efficiency so I am pleased the Vmp of the panel I bought is supposed to be 22 volts. There is no sticker on the back.
Regards Philip A

[Ferret]

...All mine say 10A.

Which means if your battery wants to draw more than 10 amps and your panel can supply more than 10 amps then you will probably be seeing smoke, hopefully only from the fuse.

Another way of looking at it is - a regulator rated at 10 amps is not a good choice for panels over ~150 watts in rated capacity. Though since you will never get rated capacity you might be able to push it a bit.

[DiscoMick]

The regulators were supplied with the panels, which are 80 watts, so they are supposed to be the right size for them. They have never given any problems.

[Dorian]

Regardless of what your battery 'wants", a MPPT solar regulator will deliver no more volts x amps than your panel V mp x A mp, less around 5% to 10% lost power. So an available 6A at 17V mp from the panel (~100W) will deliver no more than 8A at 12V (~95W) or thereabouts to the battery.

Thanks, after further reading, I hadn't understood that the MPPT controller chokes the current draw from the solar panel to keep the voltage on the panel at it's Vmp. Months ago I had read an article about MPPTs that was misleading.

Cheers Glen.