Washing off solar panels

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jza80
jza80 Registered Users Posts: 13 ✭
in General Solar Power Topics #1
My ~6 month old roof mounted panels are accumulating a nice layer of dust, probably I should rinse them off once in a while (when the temps are cool/cold...).

BUT, my city water is very hard with a lot of mineral content...I am afraid that hard water spots will form if I just use a hose on the panels, which could be worse over time than the dirt (which will eventually wash off when we get a good rain storm).

So, has anyone found a good way to clean their panels, with something that can soften the water that sprays out?

Thanks!
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,448 admin
    #2
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    Re: Washing off solar panels

    There are small and hose end water softeners that people use for washing cars--such as this one.

    However, they are expensive and may not last long.

    If your panels are on the ground, you could use a squeegee to get off most of the water and reduce spotting.

    Do the washing once and see how much power gain you get (perhaps 5-10% maximum?). On my panels (2nd story roof installation)--I could never see any difference so decided to only wash if they get really dirty.

    Also, if you panels are clean (dust, not dried on dirt), you might try a dusting rag/brush (like used on cars) to get much of the dust off without needing water (my cars are not kept clean--this was a recommendation from a co-worker years ago that seemed to always drive a very shiny Mercedes--even during water rationing)...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Mangas
    Mangas Solar Expert Posts: 547 ✭✭✭✭
    #3
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    Re: Washing off solar panels

    I wash and squeegee mine dry only if they are really ugly.

    Like Bill says, l could never tell either if I was picking up voltage. But, I figured removing dust and/or dirt would give me something.
    Ranch Off Grid System & Custom Home: 2 x pair stacked Schneider XW 5548+ Plus inverters (4), 2 x Schneider MPPT 80-600 Charge Controllers, 2 Xanbus AGS Generator Start and Air Extraction System Controllers, 64 Trojan L16 REB 6v 375 AH Flooded Cel Batteries w/Water Miser Caps, 44 x 185 Sharp Solar Panels, Cummins Onan RS20 KW Propane Water Cooled Genset, ICF Custom House Construction, all appliances, Central A/C, 2 x High Efficiency Variable Speed three ton Central A/C 220v compressors, 2 x Propane furnaces, 2 x Variable Speed Air Handlers, 2 x HD WiFi HVAC Zoned System Controllers
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  • jza80
    jza80 Registered Users Posts: 13 ✭
    #4
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    Re: Washing off solar panels

    The way the slightest shadow drops output, I assumed that the layer of dust (particularly along the bottom edge) would do the same.

    My panels are second story, so a squeegee is not an option...The soft water spray looks promising, for a once or twice a year cleaning it may be worth the cost.

    Thanks,
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  • landyacht.318
    landyacht.318 Solar Expert Posts: 82 ✭✭✭✭
    #5
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    Re: Washing off solar panels

    I only have one panel mounted flat on the roof of my van. It gets dirty easily, but it is easy to clean with a gas station type squeegee.

    I always notice an amperage improvement right after a cleaning, even when the panel warms back up.

    Most of the better squeegees have a threaded base, and I've seen extention poles to 18 feet. Perhaps these might work for you.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #6
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    Re: Washing off solar panels

    Google has released a report about their panel maintainance on their large array at
    their Googleplex in the Bay area. Report in Google doc format (slideshow)
    http://docs.google.com/present/view?id=dfhw7d9z_0gtk9bsgc
    Flat panels bad
    Tilted panels, rain washes most of it clean, but PV frame "lip" traps dirt & water
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
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    Re: Washing off solar panels

    The most troublesome cleaning problem I get is from sap-sticky-gunk that occasionally finds its way onto the panels. This requires methyl hydrate followed by Windex and full extension of the body to reach!
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  • Ralph Day
    Ralph Day Solar Expert Posts: 1,019 ✭✭✭✭
    #8
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    Re: Washing off solar panels

    Marc,
    How close are your panels to trees? Is this a fine misty sap that flies about on the breeze? Spring is bad for that.

    Ral[ph
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #9
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    Re: Washing off solar panels

    It's the big, sticky seeds from the cottonwoods that cause the most trouble. And since I'm in the middle of a forest, the trees are never far away! :D The other trees aren't much trouble, as their seeds/sap/pollen doesn't carry so far and isn't so sticky. Cottonwoods aren't good for much.
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  • Ralph Day
    Ralph Day Solar Expert Posts: 1,019 ✭✭✭✭
    #10
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    Re: Washing off solar panels

    Do they burn Marc, or is there just too much junk to bother? Sounds like willows here in Ontario.

    I wash panels whenever Environment Canada sends me some rain. Never noticed any better performance afterwards.

    Ralph
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #11
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    Re: Washing off solar panels

    Ralph;

    Cottonwood burns like paper. FWOOMP! and it's gone. Fibrous junk you can't build with. It usually rots before it dries out. Not worth cutting down, because while alive it does produce oxygen and hold the soil together by the creek.

    Mostly the panels fend for themselves and do well. You just have to keep an eye on them and make sure nothing large has stuck.
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #12
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    Re: Washing off solar panels

    My panels are ground mounted starting @ 3 feet off the ground and going to @12 feet. I have hard water but haven't found an accumilation of water spots, I turn the hose on them mostly for bird droppings. I use a painters 8' extention and a brush made for a car windshield with a scraper (for ice) on the other side, so I'll bet a car squeegee would screw right in.

    I do use the brush for snow as well, a quick brushing and the black/blue will asorb sunlight and melt any ice accumilation.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • hardrockgirl
    hardrockgirl Registered Users Posts: 1
    #13
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    Re: Washing off solar panels
    jza80 wrote: »
    The way the slightest shadow drops output, I assumed that the layer of dust (particularly along the bottom edge) would do the same.

    My panels are second story, so a squeegee is not an option...The soft water spray looks promising, for a once or twice a year cleaning it may be worth the cost.

    Thanks,

    I know you wrote this a long time ago, but I just saw it now. Did you ever think of getting rain barrels? Then the water you use to wash your solar panels would be the water that came off of your roof. It wouldn't be hard water it would be rain water. That is what we use. It is just a thought. You will have to get a pump for it.
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