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Solar Panel life expectancy


softair
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We had installed a couple of 100W flexible-ish solar panels on the roof back in summer 2017, managed by a Victron MPPT controller. They weren't cheap ones, and were fitted by the boat builder.

 

During our limited cruising last year, I noticed the amber light on the controller indicating that all was well was no longer illuminating, but our travelling / engine running made it difficult to work out if they were doing the business or not. Because of Covid fun and games we didn't get it looked at until recently, where it seems that in decent sunlight one is only producing about 10 volts, the other is open circuit. There appears to be no obvious damage to either panel.

 

This does seem extraordinarily short-lived for expensive kit - am I just unlucky? Does anyone have any clues on how long should I expect them to last?

 

Bob

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11 minutes ago, softair said:

We had installed a couple of 100W flexible-ish solar panels on the roof back in summer 2017, managed by a Victron MPPT controller. They weren't cheap ones, and were fitted by the boat builder.

 

During our limited cruising last year, I noticed the amber light on the controller indicating that all was well was no longer illuminating, but our travelling / engine running made it difficult to work out if they were doing the business or not. Because of Covid fun and games we didn't get it looked at until recently, where it seems that in decent sunlight one is only producing about 10 volts, the other is open circuit. There appears to be no obvious damage to either panel.

 

This does seem extraordinarily short-lived for expensive kit - am I just unlucky? Does anyone have any clues on how long should I expect them to last?

 

Bob

 

 

It is not unknown (indeed quite common) for this to happen with flexible panels.

 

One of the big causes is overheating as they tend to be applied directly to the boat roof, solar panels need to 'work cool' (as can be seen by better output in Winter Sun and frost on the roof). They need air circulating around AND under them. Attaching to a hot-tin-roof is not a good idea.

 

3-4 years is probably about the best you'll get.

Replace them with 'solid' panels mounted in brackets that allow air flow. They may not be as aesthetically pleasing but you get 25 years usage for less money. Win-Win.

Edited by Alan de Enfield
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Agree with all above. Ours lasted about 5 years but output steadily getting lower. Current ones 2 years or so old but selling boat soon. With sun like last few days the output seems to drop off as they get hotter.

 

But it's what they do to the paint underneath. You can actually see the pattern of the cells in the paint when you lift them.

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Mine de-laminated after 3 years, binned it and put a framed one in it's place, and as a bonus, it's the same size, but 160W as opposed to 100W.

 

 

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Thanks for the replies. I specifically didn't want framed ones standing clear of the roof - I know they flexible ones are less efficient but hadn't taken on board just how short-lived they were!

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13 minutes ago, softair said:

Thanks for the replies. I specifically didn't want framed ones standing clear of the roof - I know they flexible ones are less efficient but hadn't taken on board just how short-lived they were!

 

 

If in doubt about anything 'new' to you, just ask. Someone will have the experience of the product you are looking at.

 

Flexibles can be summed up as :

 

Short lived (3-5 years)

Large in size for their output (100w equivalent to 160w solid panels)

More expensive.

 

For the same sized space on your roof you pay 50% of the price, get 60% more wattage, and a life of ~ 25 years when using solid, framed panels.

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Try to find new old stock for uni solar pvl flexible panels. Search unisolar pvl 144.

The company went into liquidation some years ago but held a large stock at the time. Most of the liquidated stock has now disappeared but occasionally some new old stock surfaces, fortunately some are currently available on ebay. Personally,I would grab some of these immediately if I had a requirement for them. 

These are an order of magnitude better quality than the normal flexible solar panels. I believe it was because they were of a high quality that the company went into liquidation as they could not compete on price with the tumbling prices of normal framed solar panels. 

Most of the stock is on the USA and so postage will be very high but thus is offset somewhat by the low price of the panels. 

Thoroughly recommend these panels. 

  • Greenie 1
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Just to add some further uni solar details taken from ebay

"Uni-Solar PVL-128 128W 24-Volt Flexible Amorphous Solar Panel with Bottom Facing SOLDER POINTS. These are top tier finished panels. Unisolar made them this way for a specific client. These are also Grid Tie UL 1703 Listed for Systems up to 600 VDC. Which means they were made to last 20 Years. See brochure"

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40 minutes ago, reg said:

Which means they were made to last 20 Years.

 

 

That is not particularly impressive. Most (all ?) Solar panel suppliers tend to offer a 20 or 25 year guarantee that their panels will retain at least 75% of their output for 20 / 25 years, after that time the degradation seems to speed up.

 

See typical data sheet showing retention of 80% of output after 25 years.

 

Module Solvis.pdf (bimblesolar.com)

 

 

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26 minutes ago, Alan de Enfield said:

 

 

That is not particularly impressive. Most (all ?) Solar panel suppliers tend to offer a 20 or 25 year guarantee that their panels will retain at least 75% of their output for 20 / 25 years, after that time the degradation seems to speed up.

 

See typical data sheet showing retention of 80% of output after 25 years.

 

Module Solvis.pdf (bimblesolar.com)

 

 

But in this case the figure refers to flexible solar panels. So with that in mind I do find 20 Years to be impressive. It also fits into the context of the thread subject which refers to short life of flexible solar panels. 

 

  • Greenie 1
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On 02/06/2021 at 16:20, softair said:

Thanks for the replies. I specifically didn't want framed ones standing clear of the roof - I know they flexible ones are less efficient but hadn't taken on board just how short-lived they were!

You can mount framed panels lower than the mushrooms and they look quite smart if you don't like the bulky tilting arrangements?

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1 minute ago, reg said:

But in this case the figure refers to flexible solar panels. So with that in mind I do find 20 Years to be impressive. It also fits into the context of the thread subject which refers to short life of flexible solar panels. 

 

 

I was more reffering to 'made to last' rather than a 'guarantee'.

 

But yes, it does show one of the benefits of 'rigids'.

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On 03/06/2021 at 17:24, reg said:

But in this case the figure refers to flexible solar panels. So with that in mind I do find 20 Years to be impressive. It also fits into the context of the thread subject which refers to short life of flexible solar panels. 

 

According to SpaceX, the panels they sent up to the ISS last week are to replace the originals from 20 years ago - and they are flexible.

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20 minutes ago, Opener said:

According to SpaceX, the panels they sent up to the ISS last week are to replace the originals from 20 years ago - and they are flexible.

But they probably paid more for them than the average narrow boater is willing to pay.

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Look at CIGS panels. Designed & made to be fitted to metal factory roofs…I’m getting near enough full rated output when the roof is too hot to touch. Bonus is as they are made for metal seam roofs they are long & thin which works well for a narrowboat roof. The glue is like a bitumen so allows for roof imperfections. 

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The problem with flexible panel reliability is not just the panels themselves, which in ideal conditions will deliver the lifetime claimed by the manufacturers, its often the connections to them going bad -- and they're difficult or impossible to fix reliably.

 

It's a bit like battery life -- there's the number of cycles claimed by the manufacurer under ideal conditions, and then there's what actually happens with a real charging routine that bears no resemblance to the lab tests.

 

The way rigid panels are constructed tends to make the connections more reliable under real-world conditions (rain, temperature cycling, flexing, moisture ingress into connectors...) than flexible ones.

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13 hours ago, David Mack said:

But they probably paid more for them than the average narrow boater is willing to pay.

What? Purchase cost or delivery??

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