Cleaning the PV panels ???

[voyager]

Our PV system has been in for over a year now.
We live in a high rainfall area, ~160"/yr.
There is a black algae that grows on our metal roof.
I am about to go pick up the cleaning materials to clean the algae off the roof, a quaternary ammonium chloride disinfectant.

In the last few days, I've seen a Craigslist ad selling some used solar hot water panels.
The photos show a scum on those panels that is without doubt black algae growing on them.
There are signs that it may be beginning to grow on our panels also.
I want to get it cleaned off to retain the efficiency of the panels.

A quick look around at solar panel cleaners turns up all being aimed at removing calcium deposits, or just light films.
Is a quaternary ammonium chloride cleaner [alkyl-dimethyl-benzyl ammonium chloride] potentially harmful to the panels, cells, aluminum frames, etc?

How about using a pressure washer on a low setting on them?

[J.P.M.]

Our PV system has been in for over a year now.
We live in a high rainfall area, ~160"/yr.
There is a black algae that grows on our metal roof.
I am about to go pick up the cleaning materials to clean the algae off the roof, a quaternary ammonium chloride disinfectant.

In the last few days, I've seen a Craigslist ad selling some used solar hot water panels.
The photos show a scum on those panels that is without doubt black algae growing on them.
There are signs that it may be beginning to grow on our panels also.
I want to get it cleaned off to retain the efficiency of the panels.

A quick look around at solar panel cleaners turns up all being aimed at removing calcium deposits, or just light films.
Is a quaternary ammonium chloride cleaner [alkyl-dimethyl-benzyl ammonium chloride] potentially harmful to the panels, cells, aluminum frames, etc?

How about using a pressure washer on a low setting on them?

Don't use a pressure washer.

[Mike90250]

simple water and a soft car wash brush. if you are getting algae growing on the panels, you may not have enough sun on them. I would NOT use quaternary ammonium chloride cleaner [alkyl-dimethyl-benzyl ammonium chloride] on them, if it damages the seal material, you have destroyed every panel.

[Drastyn]

Be aware that using detergents to clean the panels with many brands the warranty expires. (Of course if you have problems in the future)

[silversaver]

He lives in a high "rainfall" area.... why does he worry about panel wash and calcium deposit?? WTFark

I think he needs to clean his metal roof instead. Black algae is very tough to clean and avoid if you are in the area....brushing and sanitizing

[voyager]

I decided to go to the source with my questions.
I emailed Solarworld, the panel mfgr.:

We had our PV system installation made a little over a year ago.
The panels used are SolarWorld panels.
While I am not absolutely certain, I believe they are Sunmodule Plus 280 watt panels.

We live in a high rainfall area, about 150"/year.
Black algae grows on our concrete, roof and other surfaces exposed to rain and sun. RIMG0980r.jpg



I have seen roof mounted solar hot water panels on other homes with what is almost certain to be black algae growing on them. Hot Water Panels.jpg


I am about to apply a quaternary ammonium chloride algaecide [in particular, an alkyl dimethyl benzyl ammonium chloride solution] to the roof and concrete areas with the algae growth.
This is a very common algaecide/fungicide used in pond water, on household and industrial surfaces, agriculture, etc, and is also used in food grade applications and as a preservative in some medications.

Can it also be used on the panels to remove any black algae growth on their surfaces?

If so, are there any recommendations as to its use?
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I got an answer from them:

Thank you for supporting SolarWorld.

When cleaning solar modules we recommend the use of water with a soft cloth or sponge and a squeegee.
Do not use harsh chemical cleaning products like ammonia or lye, as they can damage the solar module.
To avoid mineral spotting, use a nozzle with a wide stream of water so that water runs off the module without leaving behind minerals (as opposed to fine droplets that quickly evaporate.
Pressure washers should not be used, as they may damage modules, wiring, glass, or injure people.
To reduce the chances of thermal damage, it is best to clean modules early in the morning or late in the day.

The anti-reflective properties in the glass we use are best maintained when cared for properly.
Abrasive cleaning utensils such as razor blades should not be used to clean solar modules, as it can damage the anti-reflective coating.
For hard to remove stains or deposits a plastic surf board comb and/or magic eraser cleaning pads in combination with a gentle cleaning product can be used.
For greasy and oily residues pure isopropanol… isopropanol/water mixtures work best.
Some vinegar-based glass cleaning products have worked well, assuming they are dilute and formulated to gentle.
Car wash soaps also tend to be very gentle.
Please always do a spot test first.

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What I got from them was a noncommittal standard rubber stamp cleaning statement that did not directly address my question.
Although, they did not say that a benzylkonium solution should not be used.
The references to alcohol, vinegar, car wash soaps, ammonia, lye do not preclude the benzylkonium because it is not actually a cleaner.
It is an algaecide.
It would not be scrubbed onto the surface.
It would be sprayed onto the surface, allowed to sit, then rinsed off, maybe a squeegee or a soft brush or mop to do the final clean up.
But, they did not OK it either.
I still do not know for certain if it is OK to use it on the panels.

It is not yet an actual problem for me.
I'll see what happens and make my decision when I deem it necessary.

EDIT:
This is a high rainfall area and our domestic water is by catchment.
Mineral buildup is not a consideration.
It is obvious that there is an organic film that accumulates with time.
It becomes a food source for the algae.

[azdave]

It's very doubtful they are going to take a risk and endorse your algaecide cleaning idea if they do not have long-term testing to back it up. You and I know it is probably okay but that is just a guess on our part. Don't expect a manufacturer to go out on a limb for you if they have a chance of being held liable many years down the road.

In today's "not my fault" mindset, just the fact that algae might have been growing on them could give them reason to void a warranty claim. Lots of businesses look for any reason to deny a warranty claim, especially if you provide them with a suggestion like algae growth.


If you can determine that the anti-reflective coating is not affected by the algaecide then you are probably okay to use it. I doubt the panel maker applies the anti-reflective process to the glass so you may have to do research further up the supply chain for a better answer. Maybe another inquiry to SolarWorld might pursuade them to ask their supplier the same question since these glass coating are used worldwide in many applications beyond solar.

[J.P.M.]

On those thermal panels: That discoloration looks like it might be on the underside of the glazing. Any chance ?

[voyager]

@ JPM

Not really sure about those particular panels.
While I have noted the algae growth on panels mounted on other roofs, that particular pic was lifted from a CL ad selling them.
Seeing that ad is what sparked my question.
I have been watching my panels for the accumulation of anything that might reduce their efficiency.
I have noticed the beginning of something dark beginning to accumulate on the glass of my panels above the upper edge of the bottom frame member.
Plus, the aluminum frames are looking to be getting some algae growth on them.
When I go up to spray the roof for the algae, I'll take a close look at the panels.
After I finish treating the roof, I'll have a better idea as how well it will work on the PV panels.
My impression is that this algaecide is a spray-and-forget type of application, being removed by subsequent rains, not requiring scrubbing to remove the dead algae.
We'll see.

[Mike90250]

you would be much better off using a carwash brush, and removing the algae BEFORE it sets up shop on your panels, keep the dirt and residue off the glass, by the time you have the crud growing there, you are loosing power. And Don't use the algacide chemical on your solar panel until you are desperate to get them clean. Do not bet on a squire-and-rinse to keep them clean. Damaging the AR coating, or seals will be impossible to repair.
But they are your panel$, and that is the advice I can give.