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Dave W. Gilbert AZ
6.63kW grid-tie owner -
I agree with JPM and rinse my panels pretty much every month.
I think it makes a difference.
Luckily I have easy access to my rooftop as I have a second story balcony off the bedroom and can just walk out directly to the roof mounted panels.
Being pretty close to the coast here in SD and not getting a whole lot of rain, not counting this last winter, they do retain a bit of dirt and whatnot.
I think Ill do a little experiment and find a couple of panels that are side by side and only clean one of them and then check the production on the Enphase website for the clean and dirty panels to compare apples to apples.
My panels have a little more than 10 years of service so far and not one issue.
Older 260w Sunivas and M215 micros but they just keep going.
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Just a quick report on my cleaning one of two identical output panels that are mounted side by side.
Pretty much full sun day.
5PM output total for the "Cleaned" panel" 1.42kw
5PM output total for the "Uncleaned panel" 1.37kw
As of 12:30PM today with cloudy overcast conditions.
"Cleaned panel" 571wh
"Uncleaned panel" 552wh
I checked the outputs on all 34 panels.
The two panels I chose were not the highest producing of the groups as there are (5) panels that produce more typically.
The "Clean panel" outproduced that particular day all of the panels including the (5) higher generating ones as well, kinda interesting.
What is the difference like maybe 3% or so.
So multiply the gain by 34 panels and then 365 days it probably helps overall in a positive way since they are relatively easy to clean and access.
Just my story, nothing more nothing less.
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3.5% more production, Interesting.
Did you check that historically these two panels had the same production?Comment
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Yes these two specific panels have produced 4.19Mwh to date.
That's why I chose them as they are in direct sun and are side by side, apples to apples so to speak.
Production for today was. Pretty much sun all day long.
Cleaned panel generated 1.42kwh.
Uncleaned panel generated 1.36kwh.
As I stated before there are (5) other panels in my set-up that have produced more power historically and per day average.
Looking at the outputs of these other five they are all still less than the "Cleaned" panel.
So for me it does divinely make a difference.
Going to clean the remaining panels this weekend after my little experiment.Comment
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Thank you.
Q: So, if you clean the array 1X/month or so, that would mean that it's been about a month since the fouled tested panel was cleaned ?
If so that ~ 3 - 3.5 % difference was fouling accumulated over about 4 weeks ?.
That runs at very approximately at the same rate of ~ 2.4 - 3.6 % per 4 weeks if it doesn't rain as I've calc'd and estimated for my array.
Interesting.Last edited by J.P.M.; 08-10-2023, 03:51 PM.Comment
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A film develops on the panels and rain alone will not remove it. I use dish detergent and a brush to clean my panels. Another option is a power washer and there a nozzles designed for use cleaning solar panels. Takes about an hour to clean mine each spring.Comment
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Haven't got around to cleaning my remaining panels yet so I did a quick check on my two panels in question that I referred to earlier.
Cleaned panel has generated in the last 7 days 8.28kwh
Uncleaned panel has generated in the last 7 days 7.93kwh.
A little higher percentage than what I registered beforehand.
Same full sun exposure on both panels AND the cleaned panel is still outperforming my (4) other historically higher producing panels for the same 7 day period.
Man I gotta go clean those things soon!
Good for comparisons but bad for performance.Comment
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My 72 year old wife goes up on the roof and cleans our panels every spring using a bucket with dish detergent and a brush on a pole (same setup as for washing our vehicles). It takes her about and hour to do this.
There are special nozzles for use with power washers to clean PV panels so if you already have a power washer this is an option for some.
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Maybe your climate/situation is different, but my array seems to foul such that its performance decreases about 0.006 to maybe 0.009 per week without rain or mechanical cleaning with a hose and tap water.My 72 year old wife goes up on the roof and cleans our panels every spring using a bucket with dish detergent and a brush on a pole (same setup as for washing our vehicles). It takes her about and hour to do this.
There are special nozzles for use with power washers to clean PV panels so if you already have a power washer this is an option for some.
More importantly perhaps, the accumulated fouling or performance deterioration seems to level off at maybe a 0.10 to 0.12 decrease in performance and seems to stay there until the next cleaning or rain event that's > ~ => 0.25" or so.
Point is, Unless you've got a lot of sea air/spray, tree sap, flocks of owls that use you array as a skrock bombing range or some other unusual fouling regime, while X/year cleaning may make you feel good, I'm skeptical that it's necessary as long as it rains every couple of months or so, but suit yourself for sure.
I hose with tap water and no brush ~ 1X/month and it seems to hold the fouling penalty to an average of something like 3% of the array's clean performance. Brushing and/or squeegeeing do not improve the cleaniness or performance of my array over simple hosings with tap water at the rate of maybe 3l/panel and a drip dry. The hard water spots are mostly transparent to the wavelengths of light useful to silicon solar cels. All that might seem to fly in the face of conventional wisdom but I've been at this for ~ 10 years and collecting and keeping pretty good and thorough records, and that's my story (and data backup) and I'm sticking to it.
As for your Chinese power nozzle, 4,000 PSI as claimed by your included advert seems a bit excessive for panels, not only for edge seals but also for the anti reflective coating. Most importantly, that seems like it could cause performance problems not to mention warranty problems if discovered in a warranty claim situation.
Take what you want of the above. Scrap the rest.Comment
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I would once again mention, many solar systems can generate
lethal energy. I tell spectators, one side of mine running 360VDC
at 21A could cook dozens of hot dogs at a time. That is many
orders of magnitude beyond the lethal threshold.
So I only work on the panels after dark, using a work light. My
snow pusher is made almost entirely of non conducting plastic
and rubber. be careful, Bruce RoeComment
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This is silly. PV panels are producing current that runs in wires that should be encased in metal conduit and run to a cut-off switch and from that switch to the inverter. I can cut-off the power from my panels at the DC cut-off switch and no electricity flows to the inverter or to the grid. No more risk being near a PV array than standing beside an electric cooktop or clothes dryer or EV charger.
I made sure that my installation was to code and above. I have seen pictures of cut-off switches that were mounted so far above the ground that to reach it a ladder was needed. At least in California a new solar installation needes to be approved by the fire department as well as the utility company.
I had my inverter replaced earlier this year and the power from the PV panels was cut-off before removing the inverter. No need to have the electrician doing the work at night. Anyone ever see a solar installation being done at night?Comment
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The difference is, panels are a power source with no on/off switch.
Like a battery, unlike your appliances you can unplug. Pulling the
DC disconnect will not shut them down. Have you actually opened
the disconnect for washing? Best not let a metal pipe poke a hole
in one.
Install need not be done at night, the discussion is about servicing
a completed system. An install can wait till everything is in place,
then plug segments of a string together last, to be operational.
No problem replacing an inverter, providing all the power wires are
disconnected. An inverter does not create power. Bruce RoeComment
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