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Author Topic: How to or if to clean panels?  (Read 679 times)
cypher007
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« on: June 27, 2020, 10:47:30 PM »

Sorry if itís been asked before but,

My systems been in now for about 6 years. Iíve never cleaned the panels, but looking at them recently they look terrible.

Our roof is quite shallow so probably doesnít help.

Should I clean them? Iím always worried about damaging the special coating that keeps them generally clean.

If I clean them what if any cleaning soap should I use? Iíve got some Autoglym car shampoo thatís supposed to be gentle.
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pantsmachine
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« Reply #1 on: June 28, 2020, 08:30:23 AM »

Most of the debris will clean off with a soft brush and water and you will see a few percent lift in output. I don't use cleaning products on the panels but if you fancy it I'm sure autoglym will leave a nice finish! Be careful, go easy and don't scratch.
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GeoffM
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« Reply #2 on: June 28, 2020, 09:05:01 AM »

I have my historical output and they are producing more than ever this year (which I realise is down to the weather) but they don't seem degraded (nearly 8 years on).

My neighbour did his recently during a long dry spell and they turned out very sparkly and shiny compared to mine, and I was quite jealous. A day or so later we had some heavy rain and mine looked somewhat better, and after a few more days of pollen and whatever cr*p is in the air his are less shiny.

So on balance I'm inclined to leave well alone - you never know what you might dislodge - but I'm no expert!!
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JohnS
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« Reply #3 on: June 28, 2020, 09:33:27 AM »

It is notoriously difficult to measure or estimate how much panels have degraded over the years.

The biggest variable in the output is the amount of sunshine.  This is difficult for most of us to accurately measure but fortunately the Met Office publishes monthly sunshine hours at various locations round the country.  For me, Heathrow is less than 10 miles away.  However, sunshine hours does not take into account the quality of sunshine.  Hazy or bright?  High summer sun or low winter sun? Morning or afternoon (important with panels not facing due south)?  Clear skies - thing Icelandic volcanoes and CoVid substantially reducing flights? It might be fair to assume that quality averages out over time.

One could look at kWhs per sunshine hour and see how this changes over time.  But more sunshine hours correlates with higher temperatures which means lower output and thus the panels appear less efficient. 

Sunshine hours have trended up over the last ten years which makes the panels appear less efficient but some (most?) of that apparent inefficiency is due to higher temperatures.  Although I have monthly sunshine hours and output figures for ten years, I have been unable to calculate any meaningful degradation percentage which would stand up to statistical scrutiny.

John
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cypher007
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« Reply #4 on: June 28, 2020, 10:06:06 AM »

Mine appear to be covered in historical bird splats.

My neighbours house has 2 bird nests in its roof. Sheís in a home now and the children have never, even when she lived there, bothered to repair the roof or garage roof or anything else. So the birds have a flight path that ends up covering our cars and the panels in poop.
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brackwell
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« Reply #5 on: June 28, 2020, 10:09:07 AM »

The logical brain has to say it must make a difference but i have cleaned mine a few times over the yrs and cannot detect a difference. I have purposfully done it on a totally clear sky day and compared the output both before and after and not been able to see the difference.
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Antman
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« Reply #6 on: June 28, 2020, 10:45:23 AM »

I clean mine annually (easy with a water-fed pole). I think low roof angles like mine may increase the dirt film as water does not run off so fast so definitely worth doing.

I suspect a general dirt film has a greater effect in the winter months with low insolation - in summer the high sunlight levels probably just blast through the dirt film. OTOH, bird splat is more likely to have an effect at all times of year as they will effectively kill cells.

 
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oliver90owner
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« Reply #7 on: June 28, 2020, 11:18:38 AM »

I would guess that up to 10% may not be noticed (for uniform Ďgrimeí).  Definitely worse in the winter unless the angle of incidence is optimised for that generation (the lower light level will be absorbed by the longer path through the grime).
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biff
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« Reply #8 on: June 28, 2020, 12:04:45 PM »

 Our ground mount sits at 33%.
      We got a few deposits of Sahara pink dust which I hoses off with a long extending squeezy mop and copious  amounts of water .
   Sometimes the snow hung around too long, so I used the squeezy mop wiper blade  but only when the ice had started to thaw with the heat from the panels.
   Removing the snow certainly made a difference but I am not so sure about the coat of pink dust but it must have made some small difference 
         Biff
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Oly
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« Reply #9 on: June 28, 2020, 10:33:48 PM »

I've simply hosed ours down on a cool morning if particularly dusty or has bird poo on.  At worst I've had to use a soft brush for stubborn bird muck, but most burns off after a while.
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cypher007
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« Reply #10 on: June 29, 2020, 09:28:13 PM »

Thanks for all the suggestions. Just need to get the ladder out and buck the courage up to climb up there, as we have a house.
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Look, I ain't in this for your revolution, and I'm not in it for you, princess (renewables). I expect to be well paid. I'm in it for the money.

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book_woorm
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« Reply #11 on: June 30, 2020, 04:13:00 PM »

I use one of those water feed extending pole type window cleaners brushes to wash our panels down just to get the bird sausage off. I used to do it every leap year because I thought you would not really notice much difference and age degradation would take its toll anyway. I log all our energy usage and a few years ago I took the time to plot out the annual and monthly generation. I was quite surprised to see a drop off in output over each 4 year cycle for the annual figures and then a step up after they were cleaned. I then plotted a month by month bar chart with each of the years along side each other and it became apparent that arrival of Sahara Dust and the Tree Pollen season were having quite an effect. So I now clean them every year at the beginning of June. I can't tell if Ive had any long term age drop of in output as the annual generation seems to be on the increase so it looks as though the increase in insolation mentioned earlier is outweighing the age factor.

I'm wondering if a garden drip feed type arrangement would be just as effective at keeping the panels clean and save having to climb up there every year once it was installed. Also given that semiconductor materials work better when they are cool it might even have a use as a cooling system when the weather is very hot! It's something I could run off my rainwater harvesting as the run off would go back to the tank and not to waste.
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« Reply #12 on: June 30, 2020, 04:18:18 PM »

Just be aware, that if you are on the top of a ladder, and the sun shining, the panels MAY have a slight voltage on them. Nothing dangerous but you might feel a slight tingle! Don't fall off the ladder!
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