solar panel degradation

[Murflynn]

I have flexible monocrystalline panels on my electrically powered boat which is kept at home on a trailer most of the time.  Getting ready for this season, I checked the panels and some of them (about 5 years old) are generating very low voltage, so I am replacing them. 

 

In order to extend their life would it help to keep them covered when not needed?  I am thinking of laying a piece of carpet over them when the boat is not in use.   I can maintain the batteries by  keeping them on charge from the mains using my 20A seven stage intelligent charger.   

 

Reading up on the internet it is not clear if the main agent of deterioration is exposure to sunlight or the presence of humidity.  Obviously if it is the latter then covering with a piece of carpet would be unhelpful, and I would need to rig up something that provides a gap above the panels.

 

Any ideas?

Edited April 23, 2019 by Murflynn

[Jen-in-Wellies]

Sorry to hear this. By contrast, rigid solar panels have a life of at least 25 years. This is the figure used for calculating the financials for commercial solar farms. In practice, their life could be even longer. The panels we buy come off the same production lines in huge quantities. Not a lot of help with your flexible panels, but worth considering rigid ones if you decide to change, or add to the array.

 

Jenny

[WotEver]

Could you ask the supplier? The panels won’t like humidity obviously but they also won’t like excessive heat. The supplier might have specific knowledge of the main failure points of your particular panels. 

[matty40s]

I stopped fitting these for people 5 years ago, not only were there problems between the composite layers expanding at different speeds in the heat, thus breaking the inter cell solder joints, but they also caused issues with the underlying paint surface, often leaving condensation and rust areas underneath.

 

[reg]

9 hours ago, Murflynn said:

  Getting ready for this season, I checked the panels and some of them (about 5 years old) are generating very low voltage

5 years appears to be about the norm for flexible solar panels and, after a bit of googling, it would appear that the cheaper ones may have an even shorter life than this. 

Typical write up here (many other examples on tinternet) 

https://www.flexible-solar-panel.com/4-things-you-must-know-before-buying-flexible-solar-panels/

 

Another (scroll down to disadvantages of flexible solar panels) 

 

https://www.flexible-solar-panel.com/4-things-you-must-know-before-buying-flexible-solar-panels/

 

You may already know this but thought it may be of interest to others who may be considering buying these type of panels. 

 

I've never been a fan of these cheaper semi flexible panels but appreciate for some they may be the only viable option for their particular needs. However I would suggest that anyone who is considering these should be aware of the short lifespan. 

 

Note I do have some unisolar flexible stick panels which are of a much higher quality and are of a different construction to the general advertised flexible panels, sadly though unisolar are no more. 

[Murflynn]

1 hour ago, WotEver said:

Could you ask the supplier? The panels won’t like humidity obviously but they also won’t like excessive heat. The supplier might have specific knowledge of the main failure points of your particular panels. 

I expect the 'supplier' knows no more than the man on the Clapham omnibus.  Like everything else these days they are re-branded Chinese products.

8 minutes ago, reg said:

5 years appears to be about the norm for flexible solar panels and, after a bit of googling, it would appear that the cheaper ones may have an even shorter life than this. 

Typical write up here (many other examples on tinternet) 

https://www.flexible-solar-panel.com/4-things-you-must-know-before-buying-flexible-solar-panels/

 

Another (scroll down to disadvantages of flexible solar panels) 

 

https://www.flexible-solar-panel.com/4-things-you-must-know-before-buying-flexible-solar-panels/

 

You may already know this but thought it may be of interest to others who may be considering buying these type of panels. 

 

I've never been a fan of these cheaper semi flexible panels but appreciate for some they may be the only viable option for their particular needs. However I would suggest that anyone who is considering these should be aware of the short lifespan. 

 

Note I do have some unisolar flexible stick panels which are of a much higher quality and are of a different construction to the general advertised flexible panels, sadly though unisolar are no more. 

but would I be wise to cover them up when I don't need them, and how?

 

I have noticed that the bad ones have a milky midnight blue colour while the healthy ones are black and glossy.
 

 

Edited April 23, 2019 by Murflynn

[reg]

9 minutes ago, Murflynn said:

But would I be wise to cover them up when I don't need them, and how

An intriguing question which, although it refers to rigid panels, is partly answered here. 

 

https://energyinformative.org/lifespan-solar-panels/

 

It would appear that protecting them from the elements when not is use should help extend their life, how you do that I'm not sure hopefully others can suggest best practices. 

 

[reg]

Another interesting site

https://www.solarquotes.com.au/blog/solar-panel-degradation/

 

Shows the 5 main causes of degradation are 

• Thermal cycling: 
• Dynamic Mechanical Load:
• Humidity: 
• UV damage:  
• Freezing:

To which I personally would add poor I initial quality. 

 

So any steps you can take to mitigate the effect of the above should theoretically  help extend their life. 

[Murflynn]

thanks.  I guess I'll cover them with carpet with a few spacers to keep them well ventilated.

[reg]

If you haven't already purchased your replacements I would suggest that it might be worth googling for unisolar panels as there are still a number of liquidated stock items available albeit mainly from America. 

The unisolar panels are a different kettle of fish to the normal semi skexible panels that are sold, unisolar are a much higher quality. 

 

Midsummer energy in the UK did take steps to ensure that the technology was kept alive and now sell the unisolar equivalents under their flexisun brand. 

https://midsummerenergy.co.uk/buy/flexible-solar-panels/120W-FLEXi

These are cetrainly more expensive than the normal semi flexible panels. 

 

I actually got my unisolar from the USA, shipping cost whilst high was not so bad when spread over the 2x 120w panels I purchased. So it might be worth importing them if they suit your needs as the USA prices are lower. 

A possible Down side of the unisolar panels, although I viewed it as an upside, is that one layed down using their stick and peel then they are not going elsewhere. Another downside is that compared to rigid panels the output is quite a bit lower fir a given roof area. 

 

[Dr Bob]

Not a clue about what type of plastic used but the major cause of failure in this type of application is UV light breaking down the polymer chains causing the polymer to become brittle and thus microcrack if loads or strains are put on it. These microcracks then allow water to permeate in and cause problems.

I would therefore say that protecting them from UV (ie sunlight) would stop most of the problem but then thats the opposite of what you do all summer. Putting a carpet over them would stop the UV but keep the humidity high which then gets in due to cracking that has occurred during the summer. You cant win!

Cheap panels may have cheap polymer which may contain low levels of UV stabiliser.

For me, I have NEVER considered getting flexible panels. Not a good application for plastics.

[Murflynn]

10 hours ago, Dr Bob said:

 

I would therefore say that protecting them from UV (ie sunlight) would stop most of the problem but then thats the opposite of what you do all summer. Putting a carpet over them would stop the UV but keep the humidity high which then gets in due to cracking that has occurred during the summer.

thanks.  I think I'll erect a tent canopy over the roof when the boat is on the trailer.  I only need the generation while I'm actually cruising.

[Alan de Enfield]

11 hours ago, Dr Bob said:

Cheap panels may have cheap polymer which may contain low levels of UV stabiliser.

For me, I have NEVER considered getting flexible panels. Not a good application for plastics.

Going back some years, we quoted for the cable fixings for the 'new' Sydney Monorail system but lost out to a Taiwanese company.

Long story short - it took a few years to build, and on the inaugural trip with all of the dignitaries on board it set off - and - broke down when all of the cables 'fell-off'. They had to be rescued by the Fire Service.

 

Knowing the application and environment we had quoted for UV stabilised (2% Carbon Black) PA6.6 fastenings, the Taiwanese quoted standard grade PA6.6 at (obviously) a much lower price. 

What was the cost of rectification ?

Buy right - buy once.

 

(We did get the contract second-time around).

Edited April 24, 2019 by Alan de Enfield

[matty40s]

Just to update, this is what a semi flexible panel does to roof paint (in 12 months for this one!)

Edited May 3, 2019 by matty40s

[Ian F B]

On 23/04/2019 at 18:25, matty40s said:

I stopped fitting these for people 5 years ago, not only were there problems between the composite layers expanding at different speeds in the heat, thus breaking the inter cell solder joints, but they also caused issues with the underlying paint surface, often leaving condensation and rust areas underneath.

 

I bought my small flexible panel 2nd hand off fleabay,mounted it on a small aluminium frame,five years later still pushes out 18 plus volts on a good day.Just saying.???

[matty40s]

1 hour ago, Ian F B said:

I bought my small flexible panel 2nd hand off fleabay,mounted it on a small aluminium frame,five years later still pushes out 18 plus volts on a good day.Just saying.???

Mounting it on a frame is probably what has saved it.