Discolored Solar Panels

[JWLV]

I bought a pallet of these used panels from Santan Solar about a year go. Most of them have been stacked in my backyard since they were delivered. Today I took some panels from the pallet and I noticed that some of the panels have a rainbow discoloring around some of the cells. What is this and how does it affect production?

Picture 1: No discoloring
Picture 2: Rainbow discoloring

 

[sunshine_eggo]

I bought a pallet of these used panels from Santan Solar about a year go. Most of them have been stacked in my backyard since they were delivered. Today I took some panels from the pallet and I noticed that some of the panels have a rainbow discoloring around some of the cells. What is this and how does it affect production?

Picture 1: No discoloring
Picture 2: Rainbow discoloring

Hmmm...

Would assume heat or chemicals. Does the backside of the panel have a similarly located discoloration?

 

[JWLV]

The backside is just white, but these are the ones that Santan Solar sold as "cracked vinyl". So there are some cracks in the vinyl on the backside.

 

[sunshine_eggo]

Got nothin'

 

[Solar Guppy]

To me, that looks like the glass anti-reflection coating and it would not have any measurable effect on performance.

I bought 12 of those panels, ran for about 6 months ( no vinyl on the back $29 a panel ) and they performed as well as any other poly panel I used in the last 2 decades. $ per watt are a bargain and offer the lowest cost per watt for a system. Think of it as buying ding and dent discounted products, great value and let others pay for aesthetic perfection.

Give it a good wash and scrub with dishwashing detergent should be able to clean most of that up.

 

[JWLV]

I'll try washing it. When I hook 'em up I'll take a measurement on the amperage to see it affects anything.

I paid $42 each for these Santan panels about a year ago. Trucking from AZ to Las Vegas was $210 for the pallet. Still a pretty good deal. The top panel on the pallet was smashed. You can tell the trucking company stacked something else on top of it because the shattered glass had a rectangular shape to it. Santan took care of it pretty quickly.

By the way, for those of you who have purchased panels from Santan before. Which do you think is better, the cracked vinyl or the snail trails? Seems to me that the snail trails would likely fail sooner than the cracked vinyl.

 

[Solar Guppy]

I'll try washing it. When I hook 'em up I'll take a measurement on the amperage to see it affects anything.

I paid $42 each for these Santan panels about a year ago. Trucking from AZ to Las Vegas was $210 for the pallet. Still a pretty good deal. The top panel on the pallet was smashed. You can tell the trucking company stacked something else on top of it because the shattered glass had a rectangular shape to it. Santan took care of it pretty quickly.

By the way, for those of you who have purchased panels from Santan before. Which do you think is better, the cracked vinyl or the snail trails? Seems to me that the snail trails would likely fail sooner than the cracked vinyl.

Neither have any measurable effect on yield

The backing is for airborne debris, think sandstorm and the abrasive effect on an object. The back of the panel already has an encapsulation layer which seals and insulates. If you roof mounting panels, the missing vinyl means nothing, if your panels are ground mount, a coating of Henry's roof coating will do just fine.

On snail trails, cells are completely redundant in the flow of current, you can crack cells and it still produces the same current, from an energy production view it's unlikely anyone could even measure yield differences in the field. Maybe with a light table and calibrated wmsq source something could be noticed, but in the environment, irradiance, temperature as so variable, it would be impossible to measure.

The reason these are being sold is the power companies got to replace under warranty at manufactures expense, so literally the panels are close to just given away to places like Santan and others as disposable is more costly.

I built a 3.3kw array with used Enphase M250's for under 1K with the same panels and ran it for a year. Sold off the panels to a semi-local offgrid owner at cost and then got my current 395W half cell mono's from Santan for ~20 cents a watt, this is a 11kw system, running now 2+ years with zero issues.

 

[HRTKD]

It could be an oil residue. Clean the glass and it may go away.

I bought four used panels and they had some minor marks on the glass. I hit the glass with my machine polisher and some light polish. No more marks and the glass looks good. I don't know if the marks had any effect on production. I cleaned the glass before putting them into service.

 

[JWLV]

I took a better look at it and it appears to be under the glass. So no amount of washing or scrubbing will remove it.

 

[Consumerbot3418]

The backing is for airborne debris, think sandstorm and the abrasive effect on an object. The back of the panel already has an encapsulation layer which seals and insulates. If you roof mounting panels, the missing vinyl means nothing, if your panels are ground mount, a coating of Henry's roof coating will do just fine.

I just ordered some of these panels, and was looking into options to seal the cracked vinyl. In my area, we have mornings that can by incredibly dewy, so I was concerned about condensation eventually penetrating it. Ounce of prevention, and all... Are you pretty confident that it's unlikely to make a difference?

 

[Solar Guppy]

I just ordered some of these panels, and was looking into options to seal the cracked vinyl. In my area, we have mornings that can by incredibly dewy, so I was concerned about condensation eventually penetrating it. Ounce of prevention, and all... Are you pretty confident that it's unlikely to make a difference?

As I wrote previously, if its roof mount, adding a coating does nothing, if its ground mount where backing is exposed, spend $50 dollars and a few hours and roll on the Henry's roof coating.

As for confidence? 100%, I actual went as far to look up the tedlar vs the roof coating electrical properties and there are near identical for the application.

Solar panels are really robust and have redundant features in sealing and the cells themselves can have all sort of defects without measurable performance reductions, nothing is faster payback than these cheap poly panels. I've built 5 systems over 20 years and worked in the design of solar electronics for Xantrex and MorningStar ( with patents in mppt ).

 

[cinergi]

I bought a pallet of these used panels from Santan Solar about a year go. Most of them have been stacked in my backyard since they were delivered. Today I took some panels from the pallet and I noticed that some of the panels have a rainbow discoloring around some of the cells. What is this and how does it affect production?

Picture 1: No discoloring
Picture 2: Rainbow discoloring

That looks like what happened to my flat-mounted panels on my RV roof where rainwater collected and slowly evaporated instead of running off. Didn't cause any performance issues.

 

[Consumerbot3418]

As I wrote previously, if its roof mount, adding a coating does nothing, if its ground mount where backing is exposed, spend $50 dollars and a few hours and roll on the Henry's roof coating.

I was thinking about going with Flex Seal Aerosol, hoping to get better adhesion...

As for confidence? 100%, I actual went as far to look up the tedlar vs the roof coating electrical properties and there are near identical for the application.

I was asking about your confidence that the vinyl cracking is meaningless for roof mount. If true, I could just skip the time and effort--after all, the dew I was worried about doesn't really tend to form underneath things.

Most of them have been stacked in my backyard since they were delivered. Today I took some panels from the pallet and I noticed that some of the panels have a rainbow discoloring around some of the cells. What is this and how does it affect production?

I had the same experience with brand new panels that I'd left stacked on a pallet in the weather for several months. I didn't bother covering them, figuring they're built for outdoor environment. After installing and experiencing the sun and rain for a while, I scrubbed a bit with a rag, and it (mostly) came off. If it has any impact on production, it isn't measurable--I still have one panel I didn't scrub, and the string it's installed on produces the same as the other two, ±0.2%. One day I'll get up on the roof any scrub that one, just for the aesthetics.