Solar panel coatings

[svetz]

Saw this in a post and thought it worth discussion in it's own thread since I suspect UV is one of the main factors that causes solar panels to degrade ~.5%/yr.

... I did consider coating them [flexible panels] with a UV resistant lacquer but never got around to it...

I use 303 on my plastic Kayak... essentially it's like sunscreen and wears away after a few months. But, it does keep the side facing the sun the same color as the rest of it. The Ceramic car waxes (SiO2) are suppose to do that too. But Solar panels convert UV into power, so putting a UV block on them should rob them of power, how much? Looks like 7% from the image to the right, although probably varies vendor to vendor and the thickness of the coating. Would a thin coating knock enough energy off the damaging UV rays? UVC is completely absorbed by the atmosphere and UVB (280-314nm) is mostly absorbed while UVA (315-399 nm) is not absorbed by the atmosphere.

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Anyone ever try this or know what causes panel degradation (e.g., UVB)?

See also: Water repellent coating for solar panels

 

[svetz]

Found a paper confirming UV degrades panels, but doesn't quite work like I was thinking:

...results show that UV radiation degrades polymeric encapsulates used in PV modules construction, thereby causing loss of output power over time. Moreover, it accelerates the initial degradation of the output power and causes a greater ageing in a-Si devices compared to exposure under broadband spectrum light with higher total irradiance but lower UV content. UV degradation involves a change in colour of materials. However, the effect of UV radiation, if any, on the bare crystalline silicon cells could not be determined with confidence in this experiment.

So, that does at least suggest that something like 303 on flexible panels might lengthen their exposed lifespan.

 

[tictag]

That certainly seems to chime with my experience, from my original post:

I have to use flexible panels (weight constraints) but you'll be lucky if they last more than 3 years. Mind you, I bought cheap. The top polymer coat starts to become opaque, the cells are probably fine not that much light gets to them! And, well, from my experience, at the 5 year mark the top coat bubbles up allowing water to get in to finish the job.

I had designed a UV sensor I was going to use to try out various coatings then started look for the coatings themselves, I do remember researching at Electrolube as they have a few UV resistant conformal coatings but I never got around to buying or trying any.

Personally, I'd happily lose 7% if it meant my panels lasted longer than three years.

But I also have to add, I did buy cheap. I would expect more expensive panels to be better protected?

 

[svetz]

...I would expect more expensive panels to be better protected?...

Seems likely... ref

 

[HRTKD]

I expect my panels to last long enough for technology to change, prompting me to swap out the panels. I will clean them periodically, but with simple soap and water.