Cleaning Solar Panels.

[azdave]

Follow up...

I was up on my patio roof last weekend retrieving a wayward toy and took a few photos of my panels while I was there. These panels have been up just over one year in Phoenix Arizona USA. They face south and are at 22 degrees tilt. They have never been washed other than by mother nature. I see no need to do anything further.

[J.P.M.]

A couple more comments: I spend time in Death Valley each summer. I stop by the megaWatt size array at the Furnace Creek Ranch and check status. The Director advised me several years ago that they contract panel cleaning about every 2 years to clean the guano off, but otherwise don't clean much of anything. They monitor output and claim to not be able to see a deterioration in performance.

Also, there is a similar size array about a mile or so from my house. Its been there about 5+ years or so and I can see it as I'm typing this. I've never seen anyone performing maint. on that array, cleaning or otherwise.

On the photos, I'd probably hit the array with a hose in the early A.M.

[azdave]

If these were your panels after being on the roof for less than a month, would you get on a ladder and spray them off?
Problem is, the panels are so dirty because of the rain.

No. I know not everyone agrees.

We have significant dust storms here in Phoenix (often with only a spattering of rain to glue down the dirt). My panels have been up for over a year now. If I cleaned them each time they had some dust buildup or heavy water spots on them I'd be a slave to my system and I'd rather not have that constant hassle. I'll go up this winter to do a general roof inspection and see how the panels look. I'm not saying I would never clean them but I'm certainly not losing sleep (or significant output) from not cleaning them vigilantly.

This is my choice/situation and your mileage may vary.

[sensij]

If these were your panels after being on the roof for less than a month, would you get on a ladder and spray them off?
Problem is, the panels are so dirty because of the rain.

You have Enphase, right? I would clean just half of them, and check the panel data the next day to see if you can notice the difference.

[solar_newbie]

If these were your panels after being on the roof for less than a month, would you get on a ladder and spray them off?
Problem is, the panels are so dirty because of the rain.

No I will make my bed up there and clean every night before sleep.

[bcroe]

If these were your panels after being on the roof for less than a month, would you get on a ladder and spray them off?

If mine were that bad, I'd find a way to ground mount them. Bruce Roe

[inetdog]

Yes.

[Yaryman]

I don't worry about cleaning my panels. I live in probably one of the driest and dustiest places around...
I've yet to see anything on the panels that makes me feel like I have to get out a ladder and hose and then walk back and forth across my cement tile roof.

If these were your panels after being on the roof for less than a month, would you get on a ladder and spray them off?
Problem is, the panels are so dirty because of the rain.

[azdave]

I don't worry about cleaning my panels. I live in probably one of the driest and dustiest places around (Phoenix AZ. USA annual rainfall 6"-7"). I've yet to see anything on the panels that makes me feel like I have to get out a ladder and hose and then walk back and forth across my cement tile roof. I let the rain do the work and don't worry about a few percent solar loss compared to the damage I could cause my panels, my roof or myself. If I lived where there was heavy snow I would probably clear the panels (but I don't).

[J.P.M.]

sorta off topic, but has anybody tried rainx on panels? any performance increase during rain?

For starters, there isn't usually a lot of production from PV systems when it's raining.

The idea of using Rainex on PV panels comes up about 1X/yr or so. As I recall, in the most recent iteration, one of the moderators contacted Rainex and they seemed reluctant to say it was OK, based on lack of information or testing.

A couple of things to think about, among other things: What might be Rainex's possibly deleterious effects on the transmission/reflection/absorbance properties with respect to spectrum wavelengths important for PV ? Also, what effects might Rainex have on any anti reflection coatings or treatments applied to the surface of a solar panel ?

Also, to the degree that warranties mean much of anything, I suppose added to that might be considerations as to what effect such a treatment might have with respect to panel warranties.

FWIW, I can't seem to measure a difference in the performance of a clean array whether it has water spots on it or not. I don't know if that's because water spots have higher transmission characteristics for wavelengths important for PV production than my eye would lead me to believe, or the effect is too small to measure, or my instruments and methods can't differentiate a difference that small, or my measurement techniques suck, or all of the above and/or more. But, if I consistently cannot measure a difference in performance between a clean and unspotted array, and a clean spotted array, I believe it's safe to conclude that until I see or do something that leads me to change my mind, hard water spots don't affect my array's performance enough to warrant any extraordinary efforts to get rid of spots caused by minerals in the water.

As usual, take what you want of the above. Scrap the rest.

[diogenes]

sorta off topic, but has anybody tried rainx on panels? any performance increase during rain?

[silversaver]

I will only hose from edge of roof. If your house is 2 story high, avoid walking on top of your roof so you wont have to worry about breaking the tile or falling off

PS. You probably get excite to clean your panels the first 2 years, after that who knows.

[inetdog]

Ah, the old Air Knife trick... remember roll through car washes, and the 70mph dryer blowers ?

Also remember the Japanese traveler who mistook the new technology Dyson hand dryer in the airport bathroom for a urinal?

[Mike90250]

To avoid potential water spots from hard water, instead of a squeegee, how about a leaf blower to blow the water droplets off? I know, hard to operate from the ground when panels are on the second story roof, but how about for ground mount panels?

Ah, the old Air Knife trick... remember roll through car washes, and the 70mph dryer blowers ?

[inetdog]

All it take is water from a hose.

To avoid potential water spots from hard water, instead of a squeegee, how about a leaf blower to blow the water droplets off? I know, hard to operate from the ground when panels are on the second story roof, but how about for ground mount panels?