Clean your solar panels!

[Electricfan]

My solar installer advised me not to clean my solar panels - just let the rain do it. And mostly I've done that. They were installed June/July of 2014 and the first couple of years I got up there with a mop and a hose and cleaned them, but its a 2-hour pain in the a@@ and I've been lazy.

Well, today I finally got up there and cleaned them again, and based on my Enphase system and my Neurio, I'm now getting 10-12% more power.

The sun has been mostly shining yesterday and today. There are some clouds, but when they clear the panels go to max power. Yesterday that was 4.9kw. Today, so far (its right at noon as I type) I am getting max peaks of 5.4kw.

Moral of this story, clean your solar panels!

See picture - I took this just now to show you my panels and guess what! I missed one DAMMIT. (clearly visible in the picture) Now I have to crawl back up there... But it gives you an excellent "before" and "after" what the panels look like.

Below shows the first panel I cleaned. I sat the mop on the panel next to it, which killed that panels production. So you can compare the output of the topmost panel after cleaning, with the bottom panels. Clear improvement.

 

[Story]

Nice...I‘ve noticed similar improvement in output on my panels, but haven‘t had the benefit of Powerwall software monitoring...had to look at the ancient 2003 Sunnyboy RS232 readout!

We pay our window washers extra to wash the solar panels. (Since our house is very tall, I feel we have to hire window washers...just not worth the risk.)

 

[Electricfan]

I should have mentioned I ordered two Tesla PW2s that are coming this Friday, and that's why my motivation to clean the panels increased. I want to store as much energy as I can. I wish someone would invent a solar panel cleaning robot, like a Roomba for your roof. I'd buy one. My roof is on a gentle slope but I still don't like getting up there.

 

[Dan123]

Can you just spray them down with a hose, or is actual scrubbing necessary?

 

[DirtyT3sla]

Your post pretty much convinced me not to get solar panels. The part of the roof I'd have to put them is 3 stories up with a pretty good pitch. No way I'd be able to get up there and clean them without some special equipment...

 

[Brovane]

The question that has to be asked is the cost of cleaning the solar panels worth the extra energy you get from cleaning them?

For me it is a No. I had my panels cleaned once and it just isn't worth the cost. I have a two-story house and no way am I climbing up on my roof to clean my panels. To many ways that could go wrong.

 

[Dan123]

Your post pretty much convinced me not to get solar panels. The part of the roof I'd have to put them is 3 stories up with a pretty good pitch. No way I'd be able to get up there and clean them without some special equipment...

The higher the pitch, the less likely that you need to clean them. And it just a 10% drop anyway.

 

[Electricfan]

Can you just spray them down with a hose, or is actual scrubbing necessary?

I'm going to investigate this - I've seen some car wash products that mix solution in the water sprayed on the car - maybe that would do it. Might have to spray twice a year to get it to keep up with the dirt. But I hope this works.

But to answer your question - yes physical contact with a mop is the only thing that will get the dirt off that I know of at this point. That panel in the picture above that is filthy was sprayed down thoroughly with my hose. The pressure is pretty good - normal garden hose pressure I guess. It does no good. It just gets the dirt wet, and it looks shiny and new while wet. But as soon as it dries you see the dirt remains. (This is exactly the same with your car - if you go through a cheap "touchless" car wash - as soon as it dries you see the dirt remains on your car)

Comments about "is it worth it" - that's your call. For me its easy - yes its well worth it. My house is single story. My roof is a very gentle slope. It takes about two hours to get the hose out, get the mop and hose up on the roof, work on the panels, and put everything away again. Painful, but now in a sunny day I'll get about 4 to 6 kwh more production. Or 120 to 180 kwh per month. Definitely worth it.

 

[jbcarioca]

Everyone should be aware that solar panels do receive whatever airborne debris is around. The more atmospheric pollution from any source, the more cleaning one must plan for.
I installed panels in 1985 on an island I owned in a very remote part of the Bahamas. When I sold it in 2005 the panels had never been cleaned and were still pristine.
Panels on my house in Miami required cleaning every six months in order to maintain efficiency.
Panels on my house in Rio de Janeiro (a location about 150 meters above the beaches) have been clean since installation in 2010, with a casual spraying ~annually. In Rio we are above almost all pollution and have fairly consistent breezes.

IMHO, if one lives in a dense urban area one should plan for a regular cleaning, and should regularly monitor production efficiency to decide when to clean.
Personally I have simply used a pressure washer to clean the panels, which seems to always do the job. I do not know whether panels differ regarding their resistance to dust and dirt, but I imagine there are some significant differences.

Is there any source to test panels in this respect? I am soon to begin a new project and I'd really like to know!

 

[dhrivnak]

My solar installer advised me not to clean my solar panels - just let the rain do it. And mostly I've done that. They were installed June/July of 2014 and the first couple of years I got up there with a mop and a hose and cleaned them, but its a 2-hour pain in the a@@ and I've been lazy.

Well, today I finally got up there and cleaned them again, and based on my Enphase system and my Neurio, I'm now getting 10-12% more power.

The sun has been mostly shining yesterday and today. There are some clouds, but when they clear the panels go to max power. Yesterday that was 4.9kw. Today, so far (its right at noon as I type) I am getting max peaks of 5.4kw.

Moral of this story, clean your solar panels!

See picture - I took this just now to show you my panels and guess what! I missed one DAMMIT. (clearly visible in the picture) Now I have to crawl back up there... But it gives you an excellent "before" and "after" what the panels look like.

View attachment 412543


Below shows the first panel I cleaned. I sat the mop on the panel next to it, which killed that panels production. So you can compare the output of the topmost panel after cleaning, with the bottom panels. Clear improvement.

View attachment 412558

I am glad you saw an improvement. I have cleaned mine twice and was not able to measure a change.

 

[mswlogo]

Your post pretty much convinced me not to get solar panels. The part of the roof I'd have to put them is 3 stories up with a pretty good pitch. No way I'd be able to get up there and clean them without some special equipment...

I think it depends on your location. Slope of roof etc. Mine are 3 years old and putting out exactly what they did the first summer. Never cleaned. I think snow actually helps clean them. They will get pretty dirty during pollen season but a nice downpour will clean them up.

This person mine have tall pines nearby or something. The OP certainly did look dirty but that’s a bit unusual.

Don’t let this story convince you to not go solar. Solar is great.

 

[Electricfan]

I do live in a heavily industrial area.

I certainly didn't start this thread to discourage anyone from going solar. And my panels probably get dirtier than average both due to location and how flat they are - not angled nearly enough for optimal sun, but they have to lay flat on the roof. And they've seen snow maybe once since installation. Maybe an inch and it was gone in an hour. I let the cats out to play and they didn't like it at all.

I highly recommend solar panels. They have cut my utility bill significantly and are definitely on schedule to pay for themselves as promised when I bought them.

 

[Electricfan]

This shows my solar production. At this moment I would be storing power at a rate of 5kw into the battery, or 5kwh in one hour. I'm very curious what I end up storing using my PW2 batteries, supposed to be installed this Friday. Yes I've read all the horror stories about delays and postponed installs. We'll see what happens in my case.

 

[ReddyLeaf]

Can you just spray them down with a hose, or is actual scrubbing necessary?

As others said, definitely location and pollution dependent. In Miami, you might never need to do anything because of periodic heavy rains. Here in the eastern WA desert, it’s definitely helpful and scrubbing is required. We have a very fine “blow sand” that sticks to everything. I cleaned a friends last week with just water and a scrub brush. I’m might help adding a surfactant or detergent, but it’s not criticality important (mostly because more dust came this week with the next wind front). It’s probably better to clean weekly, just like I have to do for the patio a few hours before guests arrive. A friend in Seattle cleans his panels with a hose only, and then only once a year in May/ June after the pollen and rain slows down.

 

[Electricfan]

Here are a couple of links with good info on cleaning solar panels. Still don't know of an easy way to do it, still looking.

Best Way to Clean Solar Panels - Energy Informative

 

[Electricfan]

This is with my home's AC running, still would be banking over 2kw of power... really want those batteries...lol

 

[arnolddeleon]

The economics usually doesn't work out (additional output versus the cost). I do get my panels clean professionally cleaned every few years primarily to get an expert eye to look for damage or something that needs attention.

 

[SSonnentag]

If you live in a dusty or smoggy area, I'd highly recommend at least an annual cleaning. I'm fortunate enough to live in a non-dusty area away from city smog and we get pretty much at least some rain each month, so our panels always look clean.

 

[mswlogo]

I do live in a heavily industrial area.

I certainly didn't start this thread to discourage anyone from going solar. And my panels probably get dirtier than average both due to location and how flat they are - not angled nearly enough for optimal sun, but they have to lay flat on the roof. And they've seen snow maybe once since installation. Maybe an inch and it was gone in an hour. I let the cats out to play and they didn't like it at all.

I highly recommend solar panels. They have cut my utility bill significantly and are definitely on schedule to pay for themselves as promised when I bought them.

Solar has cut my utility bill as well, to $0.00 Actually I make a little money due to MA SREC program for the first 10 years. The Grid is my battery.

Efficiency seems to being doing good as well. Jan, Feb, Mar, Apr are all my best season yet. But that is more weather variation than panel performance. But this month has been a ton of cloud and rain but still looks like it will be about average.

 

[Electricfan]

If you live in a dusty or smoggy area, I'd highly recommend at least an annual cleaning. I'm fortunate enough to live in a non-dusty area away from city smog and we get pretty much at least some rain each month, so our panels always look clean.

That's a lot of solar, plus the batteries! How long have you had the solar panels? Installed same time as batteries? If you've never cleaned them, is your peak power still as high as its always been?

What level do you keep the batteries? How often do they drain completely? Do they charge to full every day? every week? every month? How much power do you store and then use from the batteries daily, on average? You can tell I'm very curious how the batteries work.