Energy Products

Solar panels cleaning

edited November -1 in Energy Products
I just had my solar panels professionally cleaned in San Diego. My first day after cleaning showed 10% performance improvement. My panels were not super dirty, just a thin film of dust and the seasonal rain... First cleaning in 7 years.... the cost was $160 for 34 panels...

Was it worth it?... I’m not sure... only time will tell...


  • edited January 24
    This confirms the University of Arizona’s study on solar panel cleaning showing that the benefits are not obvious... and the risks of damage or electrocution are minimizing the benefits...
  • edited January 24
    How long will a 10% production increase take to make $160? That's what you should be looking at. If that's your cleaning interval, then you're not saving any money. It varies a lot, in benefit.

    I rinse mine from the ground with a hose about every 60 days when there's no rain. (I get a *lot* of dust from the beach, less than a mile away.) I climb up on the roof about once a year with an RV cleaning brush (soft), a long pole and a hose. I put a hose bib on the roof when I did a remodel. The plumber thought I was nuts until I told him what it was for...
  • bpbp
    edited November -1
    I asked our installers about this - and they believed the heavy rains we get periodically should be enough to keep the panels clean enough to avoid having them cleaned.
  • edited January 26
    It sounds as if the benefits of taking the chance to clean the surfaces are not so great, but is there some indication that the output of the system is less because of the dirt-film? We've had our Solar City Cells for about 4-yrs. Last week I went onto the roof (Kingston, NY) to clean the gutters, & ck. out the cells. There was a 5-ft tree limb (~3"-dia) up against one of the panels, but I saw no damage.
  • edited January 29
    Live in Napa in an agricultural area (vineyards are VERY dusty). Recent fires also dumped a lot of ash. Cleaning is a regular chore for me (about 3 times a year) and impacts production considerably - the dust is easily visible. Production improves by 10-15% each time. Garden hose with pistol grip, wide broom with long handle and soft bristles...takes about 15 minutes and uses 10 gallons of water. The esthetics are also important to me - black SunPower panels look bloody awful when dirty.
  • edited April 11
    Do not clean the wiring underneath the panels. Simply use a water hose from the ground to flush the panels as needed. Tesla does not recommend customers walking on their roof. If you have excessive soiling, such as from bird droppings, you may wish to hire a local solar panel cleaning service. -
  • edited April 11
    Do note that most panel cleaning service pricing is such that any production improvement will not recover the cost to clean, when necessary cleaning frequency is taken into account. I get a 5-10% production improvement with cleaning, and I'm near the beach with it's incessant afternoon breezes (and accompanying fine sand dust).

    Do the math before considering paying to have your panels cleaned.
  • edited November -1
    Mine were installed last August (Seattle area), and I cleaned them the first time last week to get a layer of pollen off. Used a hose-end brush with a 6' extension, a light spray of Windex, and got the lower row and half the upper row. I see NO change in output, so the thin layer of pollen wasn't affecting them measurably.

    Tree pollen is now being supplanted by flower pollen, which is coming in thicker. We'll see how the rain does in washing it off this week...
  • edited November -1
    I normally don’t clean mine because the rain takes care of it. This year though the pollen was stuck to my panels and rain did nothing for them. So, I hired a guy to clean them. He charged $8/panel... Pricey in my opinion but my panels look like new and most importantly, perform like new.
  • edited April 29
    I just hosed my panels down for the second time this year. The pollen was visibly thick on all of the panels. I did see a noticeable bump on the solar graph in the app right after the flushing, both times. I haven’t tried a window cleaner or brush yet. I was worried about water spots from tap water, but I think the pollen was the worst of the two. I live in NorCal, where we don’t get much rain after the spring weather switch is thrown.
  • edited May 18
    Unless one has almost distilled quality water coming out of your hose, the panels will have residue if you don't squeegee them off or towel dry them. You will not get much benefit from just blasting them with a hose and letting them drain/dry. I found that there was noticeable solar gain/improvement after a rain storm(clean water, no minerals) cleans them, however.
  • edited May 19
    Hard water mineral residue should be far less than dust buildup. I get about a 10% gain in production, if I simply hose them off from the ground when they're dirty. No squeegee or towel necessary.
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  • Nope, dirt in solar panels has very little effect on the performance of the panels. Mine I just use a sponge to apply water and gentle soap. Also, based on experience, natural water coming from a rain boost panel output.
  • edited May 31
    It is definitely a good decision to clean
    It is recommended to do it at least once a year
  • edited May 31
    ssswww88888, I've had over twenty years of residential solar experience, and your statement that "...dirt in solar panels has very little effect on the performance of the panels." is just plain wrong. I (and others) routinely get up to a 10% performance boost by simply rinsing off dirty panels. Others have reported up to a 15% performance gain after a good scrub with a soft brush. Dust and pollen can and do negatively effect performance. Dust on solar panels has rendered Mars landers inoperative until it was blown off by a subsequent wind event.
  • edited November -1
    @gregbrew, it doesn’t rain on Mars. Rain here seems to take care of mine. I installed a sprinkler system to clean the panels, since I get a lot of tree pollen, but it stopped working at one point and production is about the same. It seems like the rain must be doing the job well enough.
  • edited June 3
    We get little rain in the arid Southwest, even in beach communities. What we do get just clumps the dust into thicker blobs, and what does accumulate enough to flow, simply collects at the bottom of the panels and obscures it. Periodic rinsing is necessary, and results in restoration of a significant amount of production, contrary to your blanket claim that "...dirt in solar panels has very little effect on the performance of the panels".

    Your claim is what I was responding to, and that claim is absolutely false, regardless of your moving the goalposts.
  • edited June 3
    @gregbrew, you won’t believe this, but just this morning as I was working at my second floor home office, suddenly a ladder clunked against the edge of my roof and a man went by with a giant squeegee. I had no idea, but our solar contract apparently includes periodic cleaning! So I stand corrected as to my own case. Quite a coincidence!

    (Note, I was not the one making the “blanket claim” in the first place.)
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