Cleaning Solar Panels.

[solar_newbie]

Wrong! Turning off the breaker just means that the panels are not supplying power to a useful load. There is still plenty of DC voltage on the panels. In the case of a grid tie system it could be as much as 400V DC, or even higher in unusual cases.
You can hope that the insulation on the wires is all good even after you soak it with water. And the water will not be a good conductor.
Some experiments have shown that even if you use salt water for conductivity you do not get a dangerous current path if the water stream has broken up into droplets by the time it hits the voltage source.
Do not try this with high voltage (power transmission lines) though.

You are right. DC voltage is still exist. For string inverter, it might go as high as 600-1000. However, for micro inverter, a single panel does not generate a lot of voltage.

[woodtiger]

I am thinking about getting a pressure water so that I can get the water up to the second story roof, and make it 'rain.' Hopefully that will be enough to clean the panels.

[8.4]

My installer said to used Simple Green. My friend's installer said use water only. I don't know who's right.

[J.P.M.]

My installer said to used Simple Green. My friend's installer said use water only. I don't know who's right.

Either one. I use dish soap and can't measure a change in efficiency whether I remove any water spots or not.

Most of solar PV is not rocket science. Cleaning panels is probably a lot like cleaning a launch pad - doesn't matter much the method as long as it's done on a somewhat regular basis with safety in mind. Just don't do it when the panels are hot and don't use a pressure washer. Shortly after sunup is perhaps best.

[solar_newbie]

Just do what you do for your glass windows... But to not gentle a little bit.

[Yaryman]

Yaryman. Could you update what the option you choose for cleaning those panels? I like to set quarterly panel clean if possible and try to learn until the first one due.

My long awaited decision on which cleaning method to use has finally been made.
After going to both Home Depot and Lowes to look at the options, I choose this squeegee product.
The plan is to just spray the panels and then squeegee them off so as to not get water spots.
I also went with a 16 foot extension product from Lowes. All the good extension poles have threads on the end.
The squeegee I selected wasn't meant for a threaded pole, so I had to place it on the top of the pole a screw that sucker down.

[Sunking]

All it take is water from a hose.

[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?

[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]

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?

[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.

[diogenes]

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

[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.

[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).

[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.