Dirty PV panels

Does anyone care? As long as the subsidies roll in. Its more cost effective to pop a diesel generator in parallel and subsidy farm with that rather than clean the panels

When, 30+ years ago, the BBC built a naturally powered TV transmitter , they had to add windscreen washer/wipers to the solar panel because of seagull mess.

I was assuming inverter design had moved on and could step up very low voltage DC of cells/panels in parallel , up to synthesised AC mains voltage, or even active switching out/bypassing of underperforming cells individually .

Yes, 'solar optimisers' are a DC-DC converter on each panel that matches the maximum power point of the panel to give the maximum achievable current through the string by tweaking the output voltage. They're not expensive, although their prices haven't been falling as much as solar panels have.

Alternatively you can fit a microinverter per (pair of) panel and just hook everything together with mains. That's a bit more expensive but good for shading.

String (conventional) inverters typically take from one to four strings, so if you only have a few panels then you can keep the strings short so shading on one panel doesn't drag the others down much.

And solar panels are so cheap nowadays that a small reduction in output doesn't really affect the economics too much.

Theo

They discuss the topic here.

The panels have to be pitched, for the rain to run off (and wash some of it off).

You can't hit them with a pressure washer.

This company uses deionized water while cleaning (and no soap). You could eat off those panels.

With the exception of companies wishing to sell you services, I don't know if I've seen pictures taken of the solar panels users doing this sort of cleaning (as a regular activity). The ones in snow country, I can believe some of those receive more attention. Even though the panels tend to get hot, if you have a snowfall at night, you can build up quite a layer on top.

Many window cleaners now use de-inonised water these days especially when using the brush on a long pole method of cleaning. It means that you don't have to squeegee off and drops of water from the glass as de-ionised water will not leave any mineral deposits when the water evaporates.

I clean my own windows and "make" my de-ionised water which I spray on with a garden sprayer as a final rinse. No need to use a squeegee or cloth to dry off the glass.

I've just spent a period in a UK rural location surrounded by fields that haven't had any rain for the past 8/10 weeks my car windscreen was covered in a fine layer of dust (blown soil) every day. I would expect the same to have happened in a UK solar farm.

I've seen videos of panels installed in very arid regions/countries when they get covered in a thick layer of dust/sand etc. and they do have to be washed down with water on a regular basis.

So, not very environmentally friendly, then, using water to clean them, in arid regions…

When has "green" energy had anything to do with being environmentally friendly? So many crackpot schemes so long as it's "not in my backyard"

As opposed to using water to drive the turbines and cool a thermal power station?

Which power sources don't use water? Wind is the only one I can think of. Solar is going to be using a much smaller quantity of water than anything with evaporative cooling, and if you are arid you don't have the convenience of a local river or sea to heat exchange into.

Theo

It's a popular research topic, and at least one cleaning company claims to already recycle the water it uses.

Another experimenter worked with organic solvents, to see if they were more effective (which is not going to be cheap). Worth checking I suppose.

I'm surprised the surface of the panel, puts up with this abuse.

Paul

I noticed a pigeon splat on one of my panels recently, I thought, ummm, because you have to carefully remove them from car body work. I carefully fired my garden hose at it, (live in a bungalow) and to my surprise it just fell off !

I get our window cleaner to clean them spring and autumn using de-ionised water. There was a lot of dust on them this week (though I couldn't see any measurable reduction in output). Anyway, yesterday's deluge of rain has restored them to sparkling.

Perhaps it has that "nano" coating that stops stuff sticking, when the glass is vertical , perhaps not at roof pitch but looser stick than without the coating.

Here on the Hants-Dorset border there have been a lot of Heath fires not too far away and presumably as you can smell the smoke there is some depositing with the dust, other parts of the UK have had similar fires but even if they haven’t some reports say that the spectacular sunsets we have been having are due to particles from fires as far away as Canada though I don’t know where they eventually fall to the ground. As you said the recent rain has given things a rinse.

I started a thread awhile back about the rise in small business offering roof cleaning thinking it seemed a bit of a contrived industry but apparently moss grows more now there are normally less pollutants in the atmosphere, presumably this new industry can easily include solar panels when they clean a roof. You just have to hope that the operator knows how to do it properly and isn’t just some thick oaf whose vape shop has gone bust and has bought a powerful pressure washer and a cheap tower and justs blasts away as their next business venture.

GH

...

We're working as hard as we can, to fill the air with smoke.

The shocking part for me, was there was a fire back home, it started near a shopping area (woods come up to that shopping area), and after many days, it was still "out of control". They had some smaller equipment for water drops, but not any of the larger planes. And when stuff like this happens, there is a danger of houses getting burned up.

We've had entire towns leveled by these fires, and the sites afterwards can be a bit toxic, and it's hard to start construction and rebuild them.

Not a good summer, in terms of the number of settlements that had to be evacuated. Some were evacuated via military flights.

Occasionally, one of these fires, it will be reported about the "fire making its own weather", and the treetops burn with a particular ferocious nature. This is partially due to drought and dried out crowns, and then the stuff burns like it was petrol or something. How do you stop those ? Even a water bomber with chemicals will have trouble.

There are several sizes of water bombers. We don't have the largest ones. We have some intermediate ones. And, we have a lot more "helicopters with buckets on the bottom". The waiting list, to have new intermediate water bombers built, might be getting close to a ten year wait. So if you have the money, there might not be any supply of a useful (float type) water bomber. I think the largest water bombers are filled at the airport. My brother in law used to work at the airport near where he lives, and was part of the team loading up chemicals into water bombers. (Hint: You don't wear your good clothes to work, even if you're a supervisor.)

The yellow one here (CL 415), is the style we use, when we have them to hand. The larger ones dropping retardant, I don't think we have any of those models. The float plane style is considered more practical here, because you can fill them via a mid-sized lake and at least drop water on a fire. The two Mars (5000 gallons?) those are retired.

We don't fight all the fires. If there are 200 of them, some will just burn merrily along, hundreds of thousands of acres. Lightning starts the fires. A lack of rain means they can run a long time. Fires near habitations, those are the ones they try to control. There have been a couple of articles about "finding creative ways to staff fire fighting on the ground". You cannot just stick any old human in the woods. One person without much experience under their belt, had a tree fall on them, killed just like that. This is why you have to apprentice with people who can judge the risks best. You can't turn your back on a tall tree, in forest fire country.

We used to have small teams of experts, who would parachute into a young fire, but we've stopped doing that (for a number of reasons I would presume). You can sometimes stop a fire before it gets too big. According to this, there are still two stations doing this. You need helicopters for support, so if the crew is surrounded, they can be lifted out. The helicopters that drop water on fires, are no good for rescuing crews.

Mine had a crust of brown dirt - maybe from building work nearby. Yesterday's first proper rain in 3 months has left them looking pristine.

Can't say the muck cut the output noticeably.