Cleaning panels

Had our system since the start of April since which, until this weekend, it has been 12 to 14 degrees (dizzy heights of 20 now), it has probably only rained properly about twice and that was in April. Needless to say the panels are covered in pigeon and seagull products and dust. Everything is working fine still but I was thinking of cleaning them as there is no rain forecast for at least a week. Any advice gratefully received. Maybe just hose them in the evening and again in the morning? It’s a bungalow so not high but I do hate ladders….

I would just get the hose out when the panels are cool and spray at them from a distance to get the roof.

You might find a window cleaner will do it, but o always worry about damage to a panel.

I would just let the sun bake the poop and wait for some thunderstorms.

No storms or anything forecast so will probably be the hose

Like I said, I wouldn’t bother myself, but you have the advantage of a bungalow 👍

Just make sure you do it when the panels are not hot.

Have panels cracked when hosed during operation I.e. when hot?
We hosed ours in an attempt to clean the tree pollen off and the only difference was a temporary increase in power as they cooled some.

John Tisbury on you tube has a very helpful video on cleaning panels. He has links to the the system he purchased, including di ionised water tank.

Did wonder about the deionised water thing as ours is rock hard and obviously there is no rain to use….

I cleaned my panels last week. Luckily they are on my workshop roof, which has a 1:12 pitch and was designed to be strong enough to be a green roof (or car park, helicopter landing pad, etc. 🙂 ). I hosed them off thoroughly and then used the window cleaning tools that I use on the house windows and greenhouse. There wasn't much difference in the output. One thing I did note for the future:- If you are using the window cleaner's sponge and scraper tool, then do the job in the very early hours of the morning or a very dull day. Otherwise the water tends to evaporate before you get to scraping it and the dirt off...

Interesting that you note very little difference in output from cleaning.

I have ground mounted panels and I clean odd bird poo splats off 3 or 4 times a week (I think we actually have a flying cow nesting nearby by the size some of them can be at times) and wondered how much the dust build up at the bottom edge of panels was reducing output.

I'm probably wasting a lot of time and effort by the sounds of it.

kram i am interested in understanding what you mean by "damage to the panel".. i was thinking of getting one of those long extendable poles to clean the panels every once in a while... will that harm the panels or do the window cleaner do something specific that can harm the panels?

A good heavy down poor is mostly good enough. But historically I have had panels cleaned every 4 - 5 years. So twice in total thus far.

To be fair, it's possible that an increase in output wouldn't be picked out of the normall variation in output from time to time. One might have to do the'before and after' tests under controlled illumination conditions to definitely spot it.

THALL wow... every 4-5 years, i was under the impression at least once every year minimum and preferably every 6 months... glad to hear thats not the case :-)

deepanshus

The cleaning brushes have the brush and the hard bit behind it that the pole goes into. I’ve seen a distraction cause a pole to dropped about a foot and the hard bit hit the glass.

Hence my caution rather than it will:

deepanshus Nah if you have a lot of tree's nearby coating the panels in various bits, or live on the coast with lots of gulls etc then every other year should do. They should self clean to an extent when it rains but if you have a lot of lichen then arranging a clean is a good idea as the rain wont get that off. But depends on your area. For me mine get dusty in the heat but nothing is growing on them yet. My oldest set of panels on this house are 3.5 years.

But for those considering getting them cleaned some window cleaners will do panels with an extension pole, gets most off but not lichen. Others more old school and generally more dangerous will go up a ladder and walk over the roof..... Others will say that scaffold is needed at a cost for a couple of hundred.

Basically wait for a couple of days of hard rain then take a look. If various things are still on them you might need a clean.

I did mine last year. The neighbour had their roof replaced and this generated lots of dust and the panels looked brown instead of black. I got one of those extendable window cleaning sets (Robert Dyas - but other makes available!). I found the soft brush made little difference, but the sponge and squeezy worked great. I live in a hard water area too and found that it was best to just use plain water, but do one panel at a time in the early morning. Apply water with the sponge side and immediately squegy it off to prevent calcium deposits as the water dries off. Start with the top panels and work down to avoid streaking

My panels were installed in August 2009 and have never been cleaned. There has been no noticeable drop in output and rainfall alone has been sufficient to keep the muck off.

Judith
After just hosing with water we bought a fancy brush with water dribble in and a very long pole and although it did a very good job of cleaning tree pollen off it made very little difference to the peak power, a few( 1-2%) at most. So the brush was not worth it even though effective.

My mum had her 4kw system installed in 2014 and when she sold the house in 2022 had never had the panels cleaned. She'd had them bird proofed as pigeons and doves were building nests under them... but never cleaned.

I kept an eye on them and the normal wind/rain kept them clean and the avg yearly FiT payments stayed in the £600-700 range the entire time they had them.

Didn't have an app or internet connected inverter at the time.

Rain forecast tonight- maybe - so I’ll wait and see

Anomnomnomaly Similar experience to me, I had FIT panels fitted 6 years ago, and never cleaned them. No obvious drop or change in FIT payments year by year.
We didn’t bother with bird proofing and never had any issues with birds nesting underneath the panels.

When the scaffolding was up for the new GE solar panel system I jetwashed the roof and the FIT panels (on a soft jet setting). There was a few bits of lichen on the panels but not a lot really.

Within a few weeks of the new panels being installed I noticed bird poo on one of the new panels that was immediately underneath the TV aerial so I bought some plastic bird guards and mastic’d them to the aerial to stop them messing up my lovely new panel. Since then (and no bird guards on the new panels either), its been fine

Yet again it didn’t rain. Maybe tonight….

SimonClarke

Give it long enough and it will rain 😂
I don’t recall any forecast saying we were going to get thunder and heavy rain.

Well it finally rained but not a lot so I tried to help it out with the hose, probably confirming what the neighbours were already thinking! Some dirts has gone but the really sticky bird product is still there. We’ve had barely any rain since mid April and I don’t think that’s helping! Doesn’t seem to be making much difference to the output - currently about 4.4kw on east west panels 8 each side, sun with patchy clouds same as before the rain/hose.

We had several heavy downpours over the past few days, and I noticed peak kWp had risen from 4 last week to the "normal" 5, so maybe the rain helped? Of course, cooler temps helped too.

Mine were absolutely filthy a couple of weeks ago...covered in dust, pollen and bird muck. A couple of heavy downpours and they are pretty clean. I've seen no real difference in output.

The best output came after a morning downpour. I guess the rain cooled the glass and once the sun hit them the evaporation cooled them further. I saw 5.6 out of my 5.2kWp setup.

If it gets hot enough bird muck will bake off 😂😂👍

Woke this morning to see our 10 x PV panels on our south facing garage roof ( on a 10 degree slope) covered in Saharan dust, as mentioned on Twitter. Decided to hose down the PV panels at 8.30am before the Sun got too hot. Took 15 mins! No rain due for a few days yet, the panels look spotless and must be more efficient? Perhaps I should have logged before and after kWh outputs?
Bill G

Although it is an American channel, some interesting findings from this Youtuber on cleaning panels and the actual gains he acheived.

"Is Solar Panel Cleaning Worth It?" (Footprint Hero with Alex Beale) https://www.youtube.com/watch?v=MQZr6J7ts04