My Experience with Washing Panels

[Matt-FL]

I've been working on finding a way to make washing my panels a less intense process, and thought I'd share my experience.

My first attempt was using a window washer micro-fiber head and a long pole (~ $30 + $30 in buckets). While this works in theory, in addition to carrying up the pole, I also had to carry up two rectangle buckets to the roof. I would fill these on the roof with a long hose. It worked, but it was a lengthy process and buckets don't work that great on sloped roofs . I'd wipe down a few panels, then 'wash' the brush in one bucket (dirty water) and then dip in the second bucket (clean water) before walking back to where I left off. I also had trouble with the long pole, as it was a bit bendy, so I couldn't scrub off some of the tougher items as well as I'd like (aka, bird poop). It worked, but I'd spend about 2 hours on the roof cleaning. My roof is not very steep, and my house is a ranch style one-story, so not really a big deal. I also noticed that after the panels dried, there was a (not sure this is the right word) film on the panels from the tap water chemicals (I'm assuming).

I watched a few videos where panel cleaning companies tout how they wash panels, and noticed the water brushes they use. I also noted the ionized water systems they used. I did some research and realized both of those can be very, very expensive. I was looking for inexpensive as I know the gain is not going to ever provide an ROI on cleaning. I personally just like to clean them once a quarter to help reduce build-up over time.

I decided if I wanted to save myself some time and simplify, I might need to spend a few more dollars. I found a water brush on Amazon with 5M of pole that claimed to be sturdy and not bend much. It was a bit pricey, about $100 (it seems to have gone up a bit since I bought it). It took a month to arrive (which was expected before I ordered).
The brush came with everything I needed, except a 1/2" to 3/4" adapter which I picked up from a box store for $5. I also purchased a two pack of inline filters to reduce the chlorine and other chems from the tap water, these were about $20 for the pair.

I used this contraption for the first time over the weekend. While it took a few minutes to sort out how to handle, carry and manage the water tubing, I was able to wash all my 51 panels in under an hour. Since the pole is far sturdier, I was also able to scrub off the persistent things off the panels. Not having to reset in a bucket each few panels was the biggest timesaver. I was surprised at how much cleaner the panels looked after washing, and the filter helped tremendously with very little 'film' from my tap water. Overall, I'd call it a success. I will have to walk around far less to clean the panels, in less time, with fewer ladder climbs. It's not a perfect device, as even when the water valve they provide you is 'off', it is more like a suggestion than reality. More like a half-off switch .
Brush: https://www.amazon.com/gp/product/B09ZY3KNCV
Filter: https://www.amazon.com/gp/product/B07Z7ML4LW

The picture below shows the brush with three of the four extension poles attached. I was able to get four panels down comfortably, I would then get the first row from the lower section of the roof. In the lower right hand corner, you can see the inline filter attached.

The other side only has 3 rows of panels on each side, these were super easy and quick to clean.

You can kind of see how the water sprays through the brush through nozzles here. I was more interested in cleaning the panels than showing their function to an audience. I got these images as I happen to have a couple UI cameras watching the roof so I can see shading through the year, paired with a UI 360 camera for viewing cloud coverage.

Anyways, hope this helps someone in the future. Happy cleaning!

 

[lodar]

Very cool! You’re much braver that I!

What % production improvements were you able to measure clean vs old?

Did the new contraption improve production compared to the old bucket method? Especially with that inline filter. Or was it mainly just less hassle?

 

[Grayson73]

I'm only in a 1 story house, so I may try a power washer from the ground. Anyone tried a power washer?

 

[BGbreeder]

My $0.02 is to check your water quality before you start. I think the magic number is TDS (Total Dissolved Solids), but it needs to be soft water. If you have hard water, my advice is not to attempt it. Ideally for any washing, you want a rinse aid or preferably reverse osmosis/deionized rinse water, neither of which is cheap at scale. (Easier to do with commercial washing companies who have someone else regenerate the deionizers for them.)

Other threads here have documented a 3-5% increase in PV performance, and the relative increase and your power costs/profits will influence the ROI. I think that a monetary ROI should not to be confused with a happiness ROI. A desire for a clean and tidy home has a different ROI for everyone...

All the best,

BG

 

[Grayson73]

I'm only in a 1 story house, so I may try a power washer from the ground. Anyone tried a power washer?

Nevermind, I just read that it's not good to power wash solar panels. You can damage them.

 

[Matt-FL]

Having city water, I knew it would have its own issues, TDS and such. Florida isn't known for fantastic water. If we did, restaurants here wouldn't offer you lemon with your water. But, I think the filter made a pretty decent difference though, just by comparing what a dry panel looked like before having it, and how it looks after. If I didn't have to go up and down the ladder to turn on/off the water, I'd do a comparison on my next cleaning.

Since it's been partly cloudy for the past while, I don't think I could calculate a % performance increase. This is my personal thoughts and circumstance, but if I didn't clean them all year, the buildup would probably make a big difference in before/after cleaning (I'm ~2.5 miles from the ocean). However, trying to clean them once a year would take a lot more scrubbing. Once a quarter makes it more of a 'touch-up' cleaning.

I suppose I could look at my max production numbers. Before, I was maxing at 15.74kW, now I'm seeing up to 16.18kW. Miniscule % change, which may have nothing to do with clean panels.

Here's been my typical sky for the past month or so...

 

[BGbreeder]

Having city water, I knew it would have its own issues, TDS and such. Florida isn't known for fantastic water. If we did, restaurants here wouldn't offer you lemon with your water. But, I think the filter made a pretty decent difference though, just by comparing what a dry panel looked like before having it, and how it looks after. If I didn't have to go up and down the ladder to turn on/off the water, I'd do a comparison on my next cleaning.

Since it's been partly cloudy for the past while, I don't think I could calculate a % performance increase. This is my personal thoughts and circumstance, but if I didn't clean them all year, the buildup would probably make a big difference in before/after cleaning (I'm ~2.5 miles from the ocean). However, trying to clean them once a year would take a lot more scrubbing. Once a quarter makes it more of a 'touch-up' cleaning.

I suppose I could look at my max production numbers. Before, I was maxing at 15.74kW, now I'm seeing up to 16.18kW. Miniscule % change, which may have nothing to do with clean panels.

Here's been my typical sky for the past month or so...
View attachment 980924

Yes tap water in Florida can have its challenges, and in many places it is quite hard.

As noted above, your increase in production (2.7%) is in the ballpark for what others have seen.

With aluminum panel frames and support, even if they are anodized, I think that you have well founded grounds to be removing ocean dust from your panels regularly. Even slightly different aluminum alloys can have galvanic action and corrosion. Being that close to the ocean, I would consider painting any part of the panels and mounts that you can. (Based on personal experience maintaining boats and homes close to the ocean...)

I think that until one gets to significant quantities of dirt/ash on a solar panel, a surface layer of "grunge" doesn't seem scatter that much light off of the panel.

All the best,

BG

 

[KHYE]

I have washed my panels 2 years in a row now. I got 4-6% production increase after washing them. I will wash only once a year, usually around June-July. First time, i bought similar water fed pole like OP but decided to return it a it's quite filmsy and I don't think it will last. I decided to get a regular extented pole. I pumped the RO water from the ground to roof using an utility pump and flexible hose.

I've been thinking of using the Titan Laboratories Glass Gleam Solar cleaner but afraid that it might affect the coating of the panels.

 

[h2ofun]

Zero interest. Why spend the money?

 

[wwu123]

Nice! I use a cheaper-style 17' water pole that I got for $45 on Amazon a few years ago (no longer available)

https://www.amazon.com/gp/product/B005GUEMQM/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

As opposed to the more professional-style brush head like yours with the thin water tubing, mine carries the water right up the middle of the aluminum extension pole, and a garden hose threads right into the open pole bottom.

I find the soft brushing to be critical here in California, as the overnight humidity seems to electrostatically bond dirt and pollen particles to the panel surfaces, even a pressure washer has issues pushing the dirt off, neither would one be advised for cleaning solar panels. But soft bristles provide just enough gentle agitation to loosen up the dirt, while just a small stream of water allows the loosened dirt to lift up and wash away, so that I'm not scratching the panel glass. Luckily too, when I remodeled the house, a few outside hose bibs ended up on the whole-house water softener, I can't use these for plants, but it works well not leaving residue after washing.

The good thing on mine is that the pole retracts sections into itself, I can twist-unlock sections to shorten/lengthen on the fly as I reach across panel rows, so I'm not maneuvering an excess of pole while navigating tight roof spaces around the panels. I can even "pump" an extra burst of water out as I quickly shorten it, if I need some extra shot of water pressure. The bad thing on mine, is at full extension, the pole is very heavy to maneuver since it is 1" inside diameter full of water extending all the way to the tip, plus I've got a few feet of water-filled hose dangling on the lower end as well.

I also use the same pole to clean my 2nd-story windows from the ground, I can reach past 20' to get to the top of the windows. There is also a squeegee on the other side of the brush, but I use a separate lighter, better squeegee - since the softened water is not really same as de-ionized water, a squeegee is needed to get windows perfectly optically free of droplet marks. But it's really tricky to balance 17' of water column above my head, I have to make sure to get the bendy pole completely vertical, and not let it get more than a foot off vertical, or the moment will have it come crashing down. On top of all this, I have a bank of clerestory windows stacked even higher above the 2nd-story, up to 34' above the ground, that I can't reach at all with the brush pole - although I have been managed to spray them with a pressure washer with long extension handle, that approach still leaves droplet marks.

So I'm really curious about the water-fed pole you purchased, as the water-fed tubing is bound to be much lighter, and can maybe reach my clerestory windows. What length of extension pole does it come with exactly, seems like each section is 1M? The listing and pictures are ambiguous, one place in the title says 5M, but elsewhere says 30'.... One place shows a retractable black/red pole, but I think most pics show aluminum sections that don't retract.....

 

[Matt-FL]

Even though the description says 'telescopic', the pole is individual pieces that snap in to each other, just like what is shown on the first picture of this brush (which looks almost identical to the one I ordered, but has different color plastic tubing):

https://www.amazon.com/Extension-Outdoor-Cleaner-Cleaning-Telescopic/dp/B099243D6C

As far as weight, the poles are aluminum and the tubing is 5mm plastic. I didn't have any issues with weight. The way the poles connect though is good and bad. Good as they are solid and there is very little bend in the poles when brushing. Bad as they can be difficult to attach/detach.

When I purchased mine, it had a number of options depending on the length you needed. the 5M/30ft pole was in the middle size. The longer ones just included additional aluminum poles to extend the reach.

 

[wwu123]

Thanks for the details, I think the rigid lightweight poles will be ideal both for the water brush as well as looks like the tip uses a "standard" thread that I could also affix a squeegee. The $80-ish ones available come in 26' kit, which might be enough for me to reach 34' above ground, but maybe just shy; others come in 35' kit (I guess 3 more poles), but twice as much. I'll keep watching out for another offering with the right amount of poles for me (29-32')