Green Building Forum - Cleaning solar panels

Cleaning solar panels

philedge — Sat, 20 Apr 2019 21:32:13 +0100

Anyone give their panels and or tubes an annual wash down? Is there any science confirming its worth it in extra output?

Cleaning solar panels

tony — Sat, 20 Apr 2019 21:52:37 +0100

A mate of mine runs several large rooftop arrays of PV

Two were identical on 30degree pitched roofs

He cleaned one of them but it made no difference, both systems clean and dirty generated the same

I have concerns about very shallow pitched panels on flat roofs

Cleaning solar panels

owlman — Sun, 21 Apr 2019 15:17:17 +0100

I bought a water fed telescopic pole, with a couple of different inter-changable heads. which I also use for roof-lights etc.. It certainly makes the panels look nicer especially the frames, not sure how it affects the output though.
Mine can get quite dirty with tree dirt and domestic bee crap.

Cleaning solar panels

tony — Sun, 21 Apr 2019 16:42:09 +0100

If it is easy then do it

Cleaning solar panels

philedge — Sun, 21 Apr 2019 20:05:08 +0100

Ive been using tree pole pruner with window washing sponge on the end but its a bit of a pain dragging a hose pipe up on the ridge of the house to wash from above.

Tonys mates experience seems pretty conclusive so I might skip every other year

Cleaning solar panels

bhommels — Mon, 22 Apr 2019 21:45:56 +0100

Most modern solar panels have cover glass sheets with self-cleaning nano coatings or patterning. Covering/filling these with limescale from tap water is not a good idea. So unless you rinse with deionised water or descaling solution I would recommend to wait for the next natural rinse cycle (rain).

Cleaning solar panels

jamesingram — Fri, 26 Apr 2019 16:35:48 +0100

most in the industry suggest they may benefit from a clean once a year.
I clean mine once or twice a year.
Id be suspicious of basing my reasoning on one single example

Cleaning solar panels

jamesingram — Fri, 26 Apr 2019 16:44:38 +0100

a quick search brings up these sites
https://www.popularmechanics.com/science/energy/news/a27112/pollution-can-block-25-percent-of-solar-power/

https://science.howstuffworks.com/environmental/green-tech/sustainable/solar-panel-cleaning-system1.htm

but.. dont pay someone if money is your goal and you live in Calafornia
https://ucsdnews.ucsd.edu/pressrelease/cleaning_solar_panels_often_not_worth_the_cost_engineers_at_uc_san_diego_fi

Cleaning solar panels

djh — Fri, 26 Apr 2019 19:50:27 +0100

I was doing a survey today that asked about my annual solar generation. I just realized that's probably a good way to answer this question too. I've kept annual generation totals, which are:

2016 3963.86
2017 3822.45
2018 3884.38

So I'm fairly happy that I'm not seeing any reduction through dirty panels
Or faulty panels (although my microinverters should make me aware of that if/when it happens)

edit: oh, I forgot to mention that I haven't cleaned them at all. They're exposed on the roof with nothing overhanging them (I saw some recently that were green with growth induced by nearby trees) but some are at a fairly flat angle (since my roof is curved, the angle varies).

Cleaning solar panels

WillInAberdeen — Fri, 26 Apr 2019 20:33:11 +0100

https://www.bbc.co.uk/news/uk-scotland-48037362
Saharan dust: Why your car is covered in red dirt

Does this stuff have any effect on solar panels? I had to clean it off my windscreen.

Cleaning solar panels

tony — Fri, 26 Apr 2019 22:34:33 +0100

Yes but it will wash and blow off again quite soon

Cleaning solar panels

Jeff B — Sat, 27 Apr 2019 08:55:46 +0100

I have only ever hosed my PV panels once or twice in the 8 years they've been up. Our tap water is very soft BTW.

Although the back walls of the house need an annual clean due to green algae (lots of trees behind the house) this does not seem to be an issue with the PV panels - maybe a combination of the rain and the special surface of the panels makes the difference?

Like djh I have not seen any gradual decline in PV output. Some variation from year to year certainly (3000 kWh +/- 10%) but no downward trend.

Cleaning solar panels

Jeff B — Sat, 27 Apr 2019 09:07:28 +0100

Just had a look at the link posted by jamesingram as above:

https://www.popularmechanics.com/science/energy/news/a27112/pollution-can-block-25-percent-of-solar-power/

Wow, no wonder those panels have reduced output - I don't think I would need a university study on my panels to tell me that I have a problem!

Cleaning solar panels

philedge — Sat, 27 Apr 2019 13:09:50 +0100

Surprised theyve got any output!!

Cleaning solar panels

Jeff B — Wed, 01 May 2019 07:24:46 +0100

Graph of our PV panels output from 2011 to 2018 attached. Output varies from (low) 2896 to (high) 3374 kWh. No special cleaning treatment. Just natural variation from year to year I would say.

Cleaning solar panels

bhommels — Wed, 01 May 2019 08:49:23 +0100

When posting generation figures can we please normalize to kWh/kWp, so divide your generation by the installed peak output rating? It makes it easier (possible) to compare outputs.

Cleaning solar panels

sam_cat — Wed, 01 May 2019 10:37:17 +0100

That chart made me twitch. Such huge variance - Then - Oh, its not 0 - x, its just showing the top of the chart.

Cleaning solar panels

Jeff B — Wed, 01 May 2019 16:37:23 +0100

Posted By: sam_catThat chart made me twitch. Such huge variance - Then - Oh, its not 0 - x, its just showing the top of the chart.

Lies, damned lies and statistics comes to mind! Graph as used by some of well known daily newspapers to make things look either terribly bad or amazingly good. I just let Excel choose on this occasion. Let the "buyer" beware and check the axis (axes)!

Cleaning solar panels

Jeff B — Wed, 01 May 2019 16:46:10 +0100

Hopefully this revised graph will satisfy both bhommels and sam_cat!

Cleaning solar panels

bhommels — Wed, 01 May 2019 16:49:54 +0100

Lovely, thanks :-)

Cleaning solar panels

sam_cat — Thu, 02 May 2019 08:11:08 +0100

Much better, thanks! :)
Far easier to see now that the variance is well within what you would expect.

Cleaning solar panels

sam_cat — Thu, 02 May 2019 08:14:04 +0100

I log mine in a similar fashion, but month on month and overlaying years:
https://i.imgur.com/XVmTYMCl.png" >

Part of a bigger spreadsheet where I monitor energy usage as well as generation.

https://i.imgur.com/TQR7F0ml.png" >

Cleaning solar panels

Jeff B — Thu, 02 May 2019 17:00:41 +0100

sam-cat - sorry but I cannot read your graphs as the image I get is tiny. Maybe it's me or my PC to blame?

Cleaning solar panels

sam_cat — Fri, 03 May 2019 09:19:54 +0100

Try these links:

Solar section charts
https://i.imgur.com/XVmTYMC.png

Solar, Electric and Gas charts
https://i.imgur.com/TQR7F0m.png

Cleaning solar panels

Peter_in_Hungary — Fri, 03 May 2019 12:23:05 +0100

Posted By: Jeff Bsam-cat - sorry but I cannot read your graphs as the image I get is tiny. Maybe it's me or my PC to blame?

Tiny image on my pc as well - however Ctrl and + together increase the size, hold the Ctrl key down and each poke of the + key steps up the size. This works for most web sites, including this one and Ctrl and - reduces size

Cleaning solar panels

djh — Fri, 03 May 2019 17:36:29 +0100

Posted By: Peter_in_HungaryTiny image on my pc as well - however Ctrl and + together increase the size, hold the Ctrl key down and each poke of the + key steps up the size.

True but that was no use with the original links. The text was unreadable even when enlarged. The second set of links cured the problem.

Cleaning solar panels

Jeff B — Fri, 03 May 2019 23:27:23 +0100

Yes, the second set of links work ok. Thanks sam_cat. Whereabouts is your installation? Mine is in west Wales.

Cleaning solar panels

owlman — Mon, 13 Nov 2023 12:07:54 +0000

Notwithstanding comments above, some of my panels are looking quite dirty with tree dirt and algae. I can't believe that production isn't affected.
I've decided that a wash and brush up is the answer . To that end can anyone recommend a suitable detergent that they have experience of. I've heard of home made concoctions of soap and vinegar but in this instance I'd rather use a tested product.

Cleaning solar panels

tony — Mon, 13 Nov 2023 13:30:51 +0000

I know people who use ‘moss killer’ what angle are your panels set at?

Cleaning solar panels

owlman — Mon, 13 Nov 2023 14:39:25 +0000

Hi tony, 34 degrees, Split array, 2 strings, one of which is a bit awkward to get to.
I have a scaff. tower, and telescopic brush kit. At the time of install I also inserted some roof hooks into the tiles, the sort Germans frequently install on their roofs, together with lightweight wooden ladders. Even so it's a bit of a reach to get downward pressure on the brush head. My plan was to wash as best I could, and then use a knapsack type spray to douse the lot in detergent, before a final rinse.