Flexible Solar panels - how do they perform?

John_Silver

John_Silver

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Our 50w roving panel staves off the rate of discharge at anchor - but that’s all. The challenge is finding space to mount fixed panels or stow roving ones on a 31’ boat.

Contemplating adding a 75w SunWare folding, flexible panel as a solution which avoids a gantry or ‘ gull wing’ mounts on the rails.

Anyone got experience of their efficiency and longevity? Is performance like for like with rigid or semi flexible panels - provided the flexible is treated with respect?
 
There are good and bad with flexible panels. The cheap PVC ones only last a couple of seasons before they start falling apart (the top laminate comes off). The ETFE panels are much tougher and last in the UV a lot better.

There are also very different efficiencies. Not all 100w panels are alike. I have found that the ones with Sunpower cells and that are back wired (the wires run behind the cells rather than over the top), are the best ones.

I used to have a single 100w panel through a PWM controller, and found that at anchor, it kept the fridge running and still put more into the batteries, so was just about keeping us going. I now have 4 x 100 panels through a Victron MPPT, and oh my word, what a revelation!

So my advice is buy ETFE panels with Sunpower cells. Look at the cell efficiency (you want something with over 20%). You still have to be gentle with them, and too much movement will break the internal cables (we have ours fixed on the bimini with velcro).
 
Bobc said:
There are good and bad with flexible panels. The cheap PVC ones only last a couple of seasons before they start falling apart (the top laminate comes off). The ETFE panels are much tougher and last in the UV a lot better.

There are also very different efficiencies. Not all 100w panels are alike. I have found that the ones with Sunpower cells and that are back wired (the wires run behind the cells rather than over the top), are the best ones.

I used to have a single 100w panel through a PWM controller, and found that at anchor, it kept the fridge running and still put more into the batteries, so was just about keeping us going. I now have 4 x 100 panels through a Victron MPPT, and oh my word, what a revelation!

So my advice is buy ETFE panels with Sunpower cells. Look at the cell efficiency (you want something with over 20%). You still have to be gentle with them, and too much movement will break the internal cables (we have ours fixed on the bimini with velcro).
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I agree with the above. I wanted 200 watts total on my boat and have bought 4 x 50 watt ETFE panels. I prefer to have four small panels instead of two 100 watt ones as the bigger the flexible panel to more likely it is to damaged, particularly, if like mine and Bobc's panels they are just velco fitted to a bimini.
 
I’ve got a semi flexible panel through an Mppt controller, currently putting around 6amps into my batteries. More than happy.
 
Bobc said:
There are good and bad with flexible panels. The cheap PVC ones only last a couple of seasons before they start falling apart (the top laminate comes off). The ETFE panels are much tougher and last in the UV a lot better.

There are also very different efficiencies. Not all 100w panels are alike. I have found that the ones with Sunpower cells and that are back wired (the wires run behind the cells rather than over the top), are the best ones.

I used to have a single 100w panel through a PWM controller, and found that at anchor, it kept the fridge running and still put more into the batteries, so was just about keeping us going. I now have 4 x 100 panels through a Victron MPPT, and oh my word, what a revelation!

So my advice is buy ETFE panels with Sunpower cells. Look at the cell efficiency (you want something with over 20%). You still have to be gentle with them, and too much movement will break the internal cables (we have ours fixed on the bimini with velcro).
Click to expand...
cool , ty ,,, which Victron controller are you using , i believe they come in different prices starting at £15 ?? is that the 1 controller covering all 4 panels ?
 
The most flexible of all are made by PowerFilm...

Rollable Solar Panels | PowerFilm Solar Inc.

They are very thin and light and can be rolled up into about a 20cm diameter roll. They are designed for military use and have some exciting features in their specification about how much they will continue to work after they've been partly shot away. They sell to non-military as well. There is a UK distributor. They are expensive in terms of £/Watt but are very well made. I have 2 28W ones.
 
cherod said:
cool , ty ,,, which Victron controller are you using , i believe they come in different prices starting at £15 ?? is that the 1 controller covering all 4 panels ?
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Victron MPPT controllers prices start at about £90. You will find solar controllers on ebay that claim to be MPPT for that amount of money but like most things in ebay that are cheap and Chinese, they are fakes. There are many videos on youtube where they are pulled apart and found to be PWM controllers. A well known brand of genuine Chinese MPPT controllers is Epever. Prices will start at £50 to £60.
 
cherod said:
cool , ty ,,, which Victron controller are you using , i believe they come in different prices starting at £15 ?? is that the 1 controller covering all 4 panels ?
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I have a 75/15. My panels are wired as 2 pairs in serial, so max output is 200w at 36v.
 
Bob,, i notice you say you have 4 x 100 giving 400 ( presumably ) tho the 75 / 15 is rated at max 200 ,, do you have more than the one or is the one sufficient.
 
cherod said:
Bob,, i notice you say you have 4 x 100 giving 400 ( presumably ) tho the 75 / 15 is rated at max 200 ,, do you have more than the one or is the one sufficient.
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Wired in series pairs, so 200w but at 36v (each panel is 100w at 18v. A pair in series gives 100w at 36v. Two pairs is 200w at 36v).
 
cherod said:
well, you seem to know what you are on about ,,, so why series and not parallel ?
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An MPPT controller can work with higher voltages, and pull the volts down, increasing the amps, whereas a PWM controller will not.

You wire in series for 2 main reasons:- 1/ It halves the amps and hence you need smaller cables and the loss is less. 2./ The controller will start to work at a critical minimum voltage. By having panels in series, you reach that voltage much sooner, so get more charging hours out of the day.
 
Bobc said:
Wired in series pairs, so 200w but at 36v (each panel is 100w at 18v. A pair in series gives 100w at 36v. Two pairs is 200w at 36v).
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Two 75/15 controllers is OK for 400w, but a single 75/15 is too small if you have a 12v battery bank.
 
noelex said:
Two 75/15 controllers is OK for 400w, but a single 75/15 is too small if you have a 12v battery bank.
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If wired in parallel, yes. Rated at 15a with max 75v.

400w at 18v = 22.2a

200w at 36v = 5.5a.

Hence my comment about needing smaller cables too.
 
Bobc said:
If wired in parallel, yes. Rated at 15a with max 75v.

400w at 18v = 22.2a

200w at 36v = 5.5a.

Hence my comment about needing smaller cables too.
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I am afraid you are incorrectly assuming the 15A limit only applies to the input. Unfortunately, it also applies to the output.

The 75/15 controller has a maximum output of 15A. This means that the maximum output at 12v is 15Ax12v = 180w. Even at a high bulk voltage, the limit is 15Ax14.8v = 222w.

Your 400w solar array can only ever output 222w into the batteries even in the most optimistic conditions.

The good news is you can add a second 75/15 controller and you will have significantly more power available.
 
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Bobc said:
If wired in parallel, yes. Rated at 15a with max 75v.

400w at 18v = 22.2a

200w at 36v = 5.5a.

Hence my comment about needing smaller cables too.
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Sorry Bob, but 400w of solar needs a 30a controller, no matter if you connect the panels in parallel or series. The 15a rating is the max charge current, not input current.
 
noelex said:
I am afraid you are incorrectly assuming the 15A limit only applies to the input. Unfortunately, it also applies to the output.

The 75/15 controller has a maximum output of 15A. This means that the maximum output at 12v is 15Ax12v = 180w. Even at a high bulk voltage, the limit is 15Ax14.8v = 222w.

Your 400w solar array can only ever output 222w into the batteries even in the most optimistic conditions.
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Ah ok, so I'm only getting about half what I should be then. Well you learn something new every day. Time to get a bigger MPPT then.
 
Bobc said:
Ah ok, so I'm only getting about half what I should be then. Well you learn something new every day. Time to get a bigger MPPT then.
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A second Victron 75/15 would be cheaper, and provides better power point tracking.
 
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