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Author Topic: Cleaning gains?  (Read 319 times)
pantsmachine
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« on: April 10, 2019, 05:40:51 PM »

Hi all,
One of the guys I am working with has oversized his 4kw system to 8kw and he swears by cleaning regularly the panels for a couple of percent gain. Online sources tout 3 to 5 % and onwards to a heady 30% improvement from dirty to clean. I am not buying into that but would be interested to hear what you guys have experienced?
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Philip R
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« Reply #1 on: April 10, 2019, 07:03:16 PM »

As every day is so different from others in terms of temperature profile, cloudiness etc. Ellucidating a meaningful figure is like licking your finger and sticking it in the air and saying about +3%.
What works for me is a sunny day like today with a cool breeze. My system generated over 21kWh today from a 3.5kW install. This often betters generated kWhs from longer, hotter summer days.

Philip R
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marshman
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« Reply #2 on: April 10, 2019, 07:49:16 PM »

I agree with Philip that it is hard to get a definitive figure for any gains.  My first system with Sharp panels is coming up to 9 years old (9 days to go). The panels are easily accessible and mounted at a shallow pitch of only 11 degrees. I used to clean my panels quite regularly. I did have a period early on of cleaning them every few months and noting the effect. More recently I have only rinsed them off if, as last year, we have a very prolonged dry spell. Last year May to August we had little or no rain so by the end of June they were pretty dusty. In all the times I have cleaned them I have noticed a temporary large increase in output due no doubt to the cooling effect of the cold water. If they were really dusty, as last year, then I guestimate I gain up to 10% extra output under similar conditions for a short period until they start to get dirty again. So in the peak season on a good day an extra couple of units a day. My overall annual generation has remained fairly constant - first year was 3268kWh, 9 years later and the last 12 months saw 3862kWh generated, average annual generation is  3578kWh. Trouble is early on I had problems with inverter tripping due to high grid volts so not  a true comparison. I think that panels at a more "Normal" angle than mine, say 30 to 45 degrees, should be pretty much self cleaning with sufficient rain. The only issue can be with bird poo and in some areas lichen growth has been reported to be a problem. I did notice some lichen starting to develop along the bottom edge of mine last year, a quick scrub with a brush and good rinse soon dislodged it, but left for a season or two it may be more difficult.

I suspect the 3 to 5% gain for regular cleaning may be in the ball park, but it depends on the situation of the panels and how dirty they and how quickly.

All a bit too subjective really and if you have made the effort to clean them then of course you will hope to see an improvement whether there is one or not!

Roger
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pantsmachine
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« Reply #3 on: April 10, 2019, 08:49:01 PM »

Thanks for taking the time to reply lads. I am in year 1 of ownership so it's all very exciting. I am looking to see if general consensus is thumbs up or down to cleaning. I have 10 months of data so will see how it pans out post clean. Thought I'd do this first then remove a couple of panels set up elsewhere and extend the leads to simulate another part of available roof. See if 5he gains are magnificent or not.
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HUGE insulation depth.
5.12 kw PV system with Solar edge.
4.8 kw Pylon tech battery storage.
All Low energy bulbs.
Solar I boost charging 210 ltr OSO system tank.
Balanced & zoned CH wet system & Hive 2
Wood fired thermosiphon cedar hot tub.
Masanobu Fukuoka inspired veg garden & fruit trees
dan_b
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« Reply #4 on: April 10, 2019, 09:21:16 PM »

If you can do it safely yourself at zero cost then by all means give them a clean on a regular basis. But if you need to get a man in to do it and pay for the effort, it probably isnít cost effective so to it more than once every few years and then only if they look really skanky.
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pantsmachine
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« Reply #5 on: April 10, 2019, 10:39:31 PM »

If you can do it safely yourself at zero cost then by all means give them a clean on a regular basis. But if you need to get a man in to do it and pay for the effort, it probably isnít cost effective so to it more than once every few years and then only if they look really skanky.

Thanks Dan, bought a hose fed brush/squeegee pole and the panels are easy enough to get to without any acrobatics. Will give it a go on return to Scotland and report if improvement seen.
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HUGE insulation depth.
5.12 kw PV system with Solar edge.
4.8 kw Pylon tech battery storage.
All Low energy bulbs.
Solar I boost charging 210 ltr OSO system tank.
Balanced & zoned CH wet system & Hive 2
Wood fired thermosiphon cedar hot tub.
Masanobu Fukuoka inspired veg garden & fruit trees
GeoffM
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« Reply #6 on: April 11, 2019, 08:21:21 AM »

Must admit I don't think mine get dirty, but next door has some too and has offered to clean mine when he does his. I declined, as they are at least working no - there's no telling what might happen if someone starts poking around with tools!! Leave well alone, I'd say, unless there is an obvious problem.
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