What cleaner to use to rid panels of hard water stains

[leonwiesener]

I have 27 panels and have recently noticed that about 1/4 of them have a yellow stain on them where they were hit with water from an irrigation system. I ordered and tried a well known solar cleaner with little effect and I'm hesitant to use something as harsh as CLR. I sure would like to hear some suggestions. By the way, I have removed the source of the stains so this next cleaning should do the trick. Thanks in advance

[Mike90250]

I don't know of ANY cleaning agents approved by panel Mfg's.

Just wait and hope some acid rain will naturally wash it away. Any harsh cleaners will damage the Anti-Reflection coating.

Maybe you can try 50% diluted vinegar, sprayed on (while panels are cool, not hot in sun) and that may soften and float away the deposits. You have to rinse this off, or it my start eating the frame and other parts.

[leonwiesener]

This is distressing. Surely there is a solution to this problem. If I were to partially remove the anti reflection layer, is there a way to replace it? The amount of stain is such that I am sure it is affecting the performance.

[Sunking]

Nothing better than plain ole vinegar to remove hard water deposits. Question is why is there hard water deposits on your panels in the first place?

[J.P.M.]

This is distressing. Surely there is a solution to this problem. If I were to partially remove the anti reflection layer, is there a way to replace it? The amount of stain is such that I am sure it is affecting the performance.

On replacing the ARC, probably not.

On affecting performance, maybe, but without information on prior efficiencyestimated by knowing input/output, you have no way to measure the decrease.

See prior threads about panel fouling. FWIW, I can't measure a difference in performance between cleaning followed by a D.I. H2O rinse and squeegeeing, and cleaning followed by a plain H2O rinse and not squeegeeing. The latter leaves some hard H2O spots that do not seem to affect performance in any way that I can measure. Opinions vary, and my efforts are far rom the last word, but that's what I did and that's what I found.

[leonwiesener]

Nothing better than plain ole vinegar to remove hard water deposits. Question is why is there hard water deposits on your panels in the first place?

I live in Florida and require a great deal of irrigation to maintain grass, plants, trees. My well which is 100ft deep is hard water with many minerals. I also live on the coast and get many 20-25 knot winds which when the irrigation system is running, whips the water up over the panels and has been for the last year. The panel are pointed south and it has just taken some time for me to fully notice their buildup but I have changed the height of the system and no longer get the spray but still need to clean the system. Have any of you heard of Solar Scrub or Evolve? Two new products on the market for breaking down hard water scale without the use of acids. Haven't gotten hold of the companies yet but both sound promising

[lugnut123]

try auto matic dish washer detergent. It is caustic based but has a sheening in it that gets rid of spots. just use a bucket and a brush and rinse it off.

[azdave]

If I were to partially remove the anti reflection layer, is there a way to replace it?

No way. Factory applied process cannot be recoated in the field. If the ARC gets stripped just leave it alone and live with it. Panel or glass replacement will never reach a payback.

Question is why is there hard water deposits on your panels in the first place?

Mentioned in his first post. Accidental overspray from irrigation system.

[J.P.M.]

try auto matic dish washer detergent. It is caustic based but has a sheening in it that gets rid of spots. just use a bucket and a brush and rinse it off.

That may not be a good idea. Kind of harsh and IMO, not that necessary, and in any event, may involve warranty voiding issues.

FWIW, some efforts I've done on trying to figure out array fouling, including the effects of cleaning in various ways, lead me to the conclusion and opinion that water spots left by simple hose washing w/tap H2O don't inhibit performance over washing w/ mild soap followed by a D.I. rinse and squeegeeing the panels - at least not in any way I can measure or quantify. A soft cloth for the "bathtub ring" at the bottom 6" - 12" or so of the panels may be a good idea 1X/awhile for the long term - 10+ yrs. or so, but even that doesn't seem to improve performance in any measureable way I've been able to discover so far.

Like most of residential solar PV, cleaning an array is not rocket science, and not too method critical as long as it's done.To that end, once I'm done with fouling measurements at some future date, my M.O. will be to hose the array in the A.M. before the array heats up about every 4-6 weeks if it doesn't rain, and accept about a 3% or so permanent penalty in output.

BTW, depending on intensity and duration, rain events seem to restore about 2/3 or so of clean performance for my location.

Take what you want o the above. Scrap the rest.

[Logan005]

Some old style hardware stores still sell a product called "Iron Out" it is a very powerful powder agent that dissolves hard water stains and is fine to use on glass, but Idk about the film coating. This irrigation mist issue should be mitigated. You risk damaging your entire array.