Washing panels revisited.

Looked back on posts and comments regarding washing panels, there were various opinions on what or what not to use to clean with but nothing with measured performance gains, so today I conducted an experiment to see for myself. Recently there has been an escavator working upwind creating dust which had left a light coating, not enough to see from a distance but visible close up.
Took a current reading before and after each panel was washed using plain water and a sponge/squeegee. Did this in the morning before they are too hot, each panel read 3.4A to 3.6A before washing and post wash measured 4.7A to 4.8A. readings taken 30 second after wash. Took another reading 15 minutes later to confirm the cooling effect didn't skewer the results, the readings were the same as the post wash, so a gain of around 1.1 amps per panel, that is a 30% improvement in peformamce.
One member claimed that anything other than leaves or shadows was negligible and washing was not necessary, I beg to differ, personally I like to put figures behind my claims if possible, hense the experiment. So my opinion is to keep panels clean for best peformamce.
Took a current reading before and after each panel was washed using plain water and a sponge/squeegee. Did this in the morning before they are too hot, each panel read 3.4A to 3.6A before washing and post wash measured 4.7A to 4.8A. readings taken 30 second after wash. Took another reading 15 minutes later to confirm the cooling effect didn't skewer the results, the readings were the same as the post wash, so a gain of around 1.1 amps per panel, that is a 30% improvement in peformamce.
One member claimed that anything other than leaves or shadows was negligible and washing was not necessary, I beg to differ, personally I like to put figures behind my claims if possible, hense the experiment. So my opinion is to keep panels clean for best peformamce.
1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
Comments
|| 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
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Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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West Chilcotin, BC, Canada
Doing the test around solar noon would make sun positioning less of an issue.
-Bill
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
But well, this is all depend on how dirty the panels is... hard to say.
luckily my system is a tracking system and I can set the panels in a vertical position and just stand in front of them to clean them. I'm glad I didn't put all my panels butted against each other otherwise I'd probably have to walk on them to clean them....
19 SW285 panels
SE5000 inverter
grid tied
I have city water for this job (well water for specific uses.)
Bird poop spots get removed from washing, panels look clean without hard water spots.
Tried a brush/water applicator once but started to think I could scratch them if not real careful. Drying might create a problem with scratches also.
And again, this is not a regular task, only when pollen collects and is not removed by rain.
19 SW285 panels
SE5000 inverter
grid tied
https://evergreensolar.com/how/cleaning/
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
In my case, grid tied, I installed largest system allowed by utility based on my electrical KWH usage from previous 365 days, (prior to design).
So it's obvious to all of us, clean panels are providing more power than dirty panels, all other parameters being equal, weather :-) it's 1% or 30% is probably debatable without hard data.
Sure, falling off a roof has it's drawbacks (I googled it), so it is not in my plan.
19 SW285 panels
SE5000 inverter
grid tied
2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.
I would think it was obvious without measuring it. Transparent materials transmit more light than translucent ones or opaque ones. Hint: Don't use paint on the panel fronts to get the colors you like to match the house, there are already colored panels available.
Saturday, at Solar Noon, I cleaned my panels for the 1st time this year, I gained 10%.
I used warm water to dissolve the crud quickly.
The previous panel was drying before I was even finished with the next panel.
This can reduce thermal shock to the glass.
Your heating your water first helped.
But throwing bucket of 50f water on a 150f panel is probably not a great idea. Just a consideration for casual readers whom may happen upon this thread.
To break a glass, you need to heat it to around 500 degrees and then submerge it in ice water quickly. I used to make glasses out of jars with this method and even then, you need to score the glass heavily first.
I had a car with a small chip /crack in the windshield. One winter morning without thinking I started car up and had heat going to the windshield. When I went back to the vehicle a few minutes later. The small issue I had beckoned now more immediately attention.
You can assume everything works and will work as designed, but why not treat your stuff more gently. Even with a warranty I would rather not deal with that process if I could avoid it.
I guess I error on the side of caution and having good practices. In general I believe those are the things we should promote.
- hard to clean bird bombs, dead bugs, etc when it dries too fast.
- full sun causes glare and hurts my eyes.
- standing in a pool of water with panels at full current may be safe, but I'm chicken.
- I wilt at much over 75°f. Shade is cool.
@Lumisol is probably right about the panels standing up to the thermal shock. A squall can go from full sun to buckets of cold rain or hail in seconds, which is probably worse. Still, I'd prefer to be elsewhere in the circumstance.
The ability to handle thermal shock likely depends some on the initial state. Strange things happen to stuff at temps <-40°f or so.
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
Incidentally, -40 is the same in Fahrenheit and Celsius.
I'm aware of how °c relates to °f. Not everyone here does though, which is why I normally specify.
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
Latin is after all the base for English, so most know it.
I am not sure they still teach it in schools, but I have taught my kids just as I learned.
I was pointing the temperature thing out to those that did not know it, as you say, not everyone does.
I used to evaluate disc and tape drives decades ago. And just the simple temperature cycling twice a day (within product specification) fairly quick ramps (something like 20 minutes from 40F to 120F)--And within two weeks of this, about 80% of the commercial products (at the time) would fail. Traces delaminate, solder joints fail, flex circuits delaminate, surface mount components pop-off, etc.
Solar panels have lots of laminated layers--And the amount of stress that can happen from shock cooling one side and thermal mass on the other side of a "layer"--Lots of bad things can happen.
Because solar cells are (especially now) extremely thin, and the backing is plastic (with low thermal mass, low heat transfer capability), running a hose on a hot panel is probably not the worst thing that could be done (with a well designed/manufactured panel).
-Bill
That is not a thing that can happen to a piece of glass. If fact, that is the reason that the new data storage methods use glass crystals to store data.
https://www.theverge.com/2016/2/16/11018018/5d-data-storage-glass
It is also not a thing that can happen to the glass over your PV panels. And it's certainly not anything worth worrying about.
Ratio absentis, impulsum, quando praecepta
- Bill
|| 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 ,