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Solar Panel Cleaning Time

Discussion in 'Energy, Environment, and Policy' started by Owner, Apr 14, 2013.

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How often do you clean (yourself or by a contractor) your solar panels?

  1. I clean my panels less than once a year

    23 vote(s)
    57.5%
  2. I clean my panels around once a year

    8 vote(s)
    20.0%
  3. I clean my panels a few times a year

    5 vote(s)
    12.5%
  4. I clean my panels more than four times a year

    4 vote(s)
    10.0%
  1. Owner

    Owner Active Member

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    I just had my solar panels cleaned as it is the beginning of peak power generation, and the end of the rainy season in California. I'm wondering how often you clean your solar panels?

    I have my solar panels cleaned once a year. I live in an area that is fortunately not particularly polluted as there is little development between me and the ocean. The winds are always from the ocean, so the panels do not get particularly dirty. I did not clean them for the first four years as I simply forgot about the need. I did notice a big improvement in power generation after the first cleaning about 20-25%.

    For the last couple of years, I have been cleaning them yearly in the beginning of spring. With PG&E it is very difficult to get good data on how much power the panels produce.
    I just had mine cleaned by the same person who had just cleaned the panels of Martin Eberhard, who was the former Tesla CEO. The solar panel cleaning man is a very talkative fellow.


    I am thinking once a year is probably the right amount of time between cleanings, which cost $125.

    Before and after photos are here.


     
  2. Kaivball

    Kaivball Member

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    Kalifornia
    I do it annually myself. I live in San Jose.

    Will probably do it next weekend.
     
  3. Raffy.Roma

    Raffy.Roma Active Member

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    I don't manage to see the difference between the before and after situation. Maybe that this happens because I have not experience of solar panels.
    Do you get an efficiency improvement of the solar panels after cleaning them?
     
  4. DrComputer

    DrComputer Member

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    I have the Tigo Energy optimization and monitor system with my solar system. It give real time information for each panel and keeps a running history of production. I can easily see a 3-5% improvement each time I clean off my panels with a hose. I try to do it monthly (but sometimes I'm lazy and it happens every two months)
     
  5. bonnie

    bonnie Oil is for sissies.

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    Same here - heavy pollen buildup and I see an immediate improvement - summers, it's a sat morning quick scrub, use windex cleaning pads, done in 10 min
     
  6. toutizes

    toutizes Member

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    Around Palo Alto I have a lot of pollen build up on the panels. I clean them myself using a hose and the swimming pool long brush. By looking at the instant output on the meter before/after the cleaning I see about 15% improvement.

    Thanks for the reminder, Owner, it's indeed the right time to clean them !
     
  7. Sparky

    Sparky Member

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    Yeah, was just on the roof with a hose and squeegee.
    One of my kids, who is about to graduate with an engineering degree, modified a Roomba to clean a section of panels on my roof that are flat and collect a lot of dust. As a solar panel appliance, it's not quite finished product. So, I put it to work on my garage floor, which also gets very dusty. It works quite well. But now that I've seen how much better my garage floor looks clean, I'm refinishing the floor and cleaning the garage so the Roomba can work more freely. Sometimes I hate new technology.
     
  8. Tesla 940

    Tesla 940 Member

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    Location:
    Long Beach, CA & Taos, NM
    10 years experience

    I nearly 10 years I've found that the garden hose is enough to wash the dirt off the panels. Once every month during the spring,summer,fall is all that is needed. I also found about a .25 - .50 kwh per day effect.
     
  9. PeterW

    PeterW Member

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    Palmerston North, New Zealand
    We have had our PV system up and running for all of 18 days:smile:

    We were told the rain will do the trick, but when it does not rain and gets dusty use the garden hose. Will look at doing that monthly in the dryer months.
     
  10. bonnie

    bonnie Oil is for sissies.

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    Unfortunately (or fortunately :) ), I have enough panels on the roof that I cannot reach everything with the hose from below. But a ladder works, too.

    Watching the green pollen-laden water hit the gutters is always satisfying. But looking at my system output and seeing the spike where I washed the panels is even more so.
     
  11. Owner

    Owner Active Member

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    The difference is not very striking. Just a layer of light dust really. One year's buildup.

    It has been super windy though in the last few days.

    I'm not sure if doing this once a year is even worth it for me, maybe every two years! : )

    - - - Updated - - -

    Mine require a giant ladder, a somewhat scary traverse onto the roof itself, and an obstacle course to get over to the panels.

    I had not thought of simply spraying a hose from a ladder against the house without going onto the roof.
     
  12. mcornwell

    mcornwell Active Member

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    I washed our 33 panels last June for the first time, they were about 18 months old at that point. They were pretty dirty, and the job took about 3 hours since I had to drag a ladder onto the roof, bring buckets of water, squeegee's, towels, etc.

    I only noticed maybe a 2% improvement in production. With clouds coming and going, it's nearly impossible to know how the difference in one days production is related to panel cleanliness, but you can look at the peak hourly output of one day an compare it to the next to get some reference.

    Since we produce about $3,000 worth of electricity/year, I'm not sure if it's worth paying someone more than $60 to do it, based on purely a financial basis, but like many, it's more of a efficiency/environmental thing, so I'll probably go up there again next month.
     
  13. Owner

    Owner Active Member

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    I just looked at some of the PG&E data before and after. I went from maybe -.71 KWh peak before cleaning to -.77 KWh peak after cleaning as a best guess. I probably jumped the gun on cleaning them this time as that is less than 10% improvement. I did notice a 20% improvement after I had waited 3 years the first time. Now at least I have these numbers noted and can watch it the same time next year.

    I have the PG&E charts on my blog post, if anyone is interested.
     
  14. VolkerP

    VolkerP EU Model S P-37

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    The immediate rise in panel output when hosing them down might as well be caused by cooling them. 10°C down gives 5% more output. You would need the next day with rather comparable conditions to identify a solid increase in output.

    And no, permanently watering your panels will not help. deposits and algae will diminish output really fast.
     
  15. mcornwell

    mcornwell Active Member

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    Isopropyl alcohol should do the trick then!
     
  16. TurboFroggy

    TurboFroggy Member

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    Living in the Seattle area with no close trees, my panels are washed at least once a week by mother nature. I have never cleaned my panels since 2009 and my output has not diminished.
     
  17. stevezzzz

    stevezzzz R;SigS;P85D;SigX

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    My solar PV system installer told me it's not worth the bother to clean the panels; I don't have any trees tall enough to drop leaves on them. What is a bigger issue for me here in Colorado is snow. Even though we have 300 days of sun annually, when the snow does fly my PV system can be totally shut down for several days until melting exposes enough surface area for it to start generating electricity again (I haven't figured out how the cells are wired, but it takes almost complete clearing of a string of panels before electricity starts to flow). The panels are not accessible from the ground, either, and my days of climbing tall ladders and working on roofs are behind me.
     
  18. bonnie

    bonnie Oil is for sissies.

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    The pollen in the air here is thick enough that when I wash the panels, the water flowing off is dark green. Biweekly for me, weekly is optimal. My production report spikes noticeably at time of washing.
     
  19. AudubonB

    AudubonB Mild-mannered Moderator Lord Vetinari*

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    Well, as my first bank of panels sits 65 feet off the ground, as in (look in background, not foreground, below):
    upper solar panels.JPG
    I'll give a squeegee AND a banana to anyone who volunteers to clean 'em for me!

    In all seriousness, as with Stevezzz, it is snow covering the panels that gives us the most problem. With my much larger bank of ground-mounted panels, we have a well-established routine of brushing the panels with a shop broom - with our dry snow, that works just fine. But the for the array of four in this photo, I have attached a single loop of 3/16" stainless cable, one end attached to each side of the rack and long enough to loop to the ground, and sometimes I am able to jerk the snow off by man-handling that cable. I do have to be careful not to destroy the rack - hasn't happened yet.

    Fortunately, airborne pollutants are something we don't encounter here, other than heavy amounts of white spruce pollen that vanishes with the first rainfall.
     
  20. rjcbox

    rjcbox Member

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    Location:
    NJ, USA
    Never cleaned since install 4 years ago. Installer said just let the rain take care of it. Production drops ~1.5% year-over-year, which I believe is within spec. Maybe flat/minimal-angled panels need cleaning - mine are ~30% tilt.
     

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