Keeping your panels clean?

[BIGFOOT]

Has anyone ever applied a Rain-X, car wax or ceramic car wax.... to help keep their panels clean? If so which do you find the most effective? Is a regular glass cleaner ok to use?

 

[Bob B]

A ceramic car wax probably has UV protection ..... which would probably cause loss of performance.

I'm not sure if Rain-x does or not.

There was another thread about this a while back .... might be worth a search for it.
I wish someone would do some real world testing on this.

 

[BIGFOOT]

A ceramic car wax probably has UV protection ..... which would probably cause loss of performance.

I'm not sure if Rain-x does or not.

There was another thread about this a while back .... might be worth a search for it.
I wish someone would do some real world testing on this.

Sounds like a project video for Wil Prowse!

 

[tigerwillow1]

My panels get covered with dust from blowing loose soil. They get coated pretty heavily. I don't mean a measurable thickness, just totally dirty. They are ground mount panels that are easy to hose off and did it occasionally until I measured the difference in output. What I measured was that cleaning the dirt off made no difference in output than I could measure, and I quit cleaning them. Might be different with different pollutants in the air. I'm in a very dry dusty climate, and they can go up to 6 months at a stretch without rain.

 

[pollenface]

I get good results with window cleaner and a cloth.

 

[chrisski]

I also measured no noticeable output when I cleaned my panels.

If I imagined hard enough, I might imagine I gain 1%, but that is well inside the margin of error.

I do clean them off with window cleaner and paper towels.

 

[Kornbread]

Many car waxes have abrasives in them to help clean oxidation and other contaminates from the paint. Not sure how that would affect the transmissivity of glass.

 

[el-guapin]

I would stay away from any cleaner /protectant. Hose off with water once, maybe twice, a year.

 

[Porch]

I am unsure if this was related, but with 30 years of using solar panels, the one I had fail was at the lower part of the rack and covered with dirt along with bottom edge covering some of the cells. It was a split panel and the bottom cells where the ones that failed.

The company that made the panel got bought out by PB and after much research, I found the right contact at PB and they warranted the panel and replaced it.

 

[wattmatters]

I wish someone would do some real world testing on this.

There's plenty of published research on this. Example.

Performance degradation from regular environmental exposure in locations that receive rain isn't much and rarely returns enough to justify paying someone to clean panels. Even in very polluted cities the loss is ~2%.

In essence, tilted panels which get rained on generally won't need much in the way of cleaning. If the panels are flat then an occasionally clean is probably warranted.

If there is an unusual event with a heavy particulate load such as a bad dust storm or heavy local fire events, then perhaps a hose down is warranted.

Else just clean off anything that looks to be a bit more of a permanent problem, e.g. a particularly persistent drop of bird shit, or lichen growth, or accumulated crud along the lower frame edge for shallow tilt panels.

While some people do home testing showing big performance gains after cleaning, they usually lack the controls necessary to consider the data reliable.

But most importantly, if you are cleaning panels, keep safety first in mind.

 

[robby]

I get good results with window cleaner and a cloth.

I would not do that. I use to clean my Oled TV screen with Windex and about a year later I noticed some odd dull patches in the screen when the TV was off. A quick search and later I found out that the glass is coated with a chemical to reduce glare. That coating is slowly melted by windex and other cleaners. Now I only use a damp cotton cloth to clean my new TV.
I have no idea if solar panel glass has a coating on it but from my own visual inspection I suspect that it does.

 

[Bob B]

There's plenty of published research on this. Example.

Performance degradation from regular environmental exposure in locations that receive rain isn't much and rarely returns enough to justify paying someone to clean panels. Even in very polluted cities the loss is ~2%.

In essence, tilted panels which get rained on generally won't need much in the way of cleaning. If the panels are flat then an occasionally clean is probably warranted.

If there is an unusual event with a heavy particulate load such as a bad dust storm or heavy local fire events, then perhaps a hose down is warranted.

Else just clean off anything that looks to be a bit more of a permanent problem, e.g. a particularly persistent drop of bird shit, or lichen growth, or accumulated crud along the lower frame edge for shallow tilt panels.

While some people do home testing showing big performance gains after cleaning, they usually lack the controls necessary to consider the data reliable.

But most importantly, if you are cleaning panels, keep safety first in mind.

I was talking more about the OP's original question ........ testing various waxes to see if they reduce productivity.

 

[Wellbuilt]

Mine get a heavy green pollen in the spring and it cuts a little production but it washes off in the rain .
The snow gets them clean in the winter ? when it slides off .
I don’t clean mine

 

[wattmatters]

I was talking more about testing various waxes to see if they reduce productivity.

Personally I would stay within the cleaning guidelines of the panel manufacturer.

My grid system has Trina panels and following is the text about cleaning from their installation manual (more recent models have updated instructions):

• The amount of electricity generated by a solar module is proportional to the amount of light falling on it. A module with shaded cells will produce less energy and therefore it is important to keep modules clean.
• Normally rain water is sufficient to keep the modules clean however it is particularly important to ensure that the solar modules are clean before onset of summer. Products installed at a tilt angle below 10° or which are located in particularly dusty areas, are installed in landscape orientation or in areas of high pollution or close to large bird populations will require more regular cleaning.
• When cleaning the module use a soft cloth together with a mild detergent and clean water. Take care to avoid severe thermal shocks which might damage the module by cleaning modules with water which has a similar temperature to the modules being cleaned.
• When cleaning the back surface of the module, take care to avoid penetrating the substrate material. Modules that are mounted flat (0° tilt angle) should be cleaned more often, as they will not ''self-clean'' as effectively as modules mounted at a 10° tilt or greater.
• The benefit of cleaning dirt and debris from the array is a trade-off between the cost of the cleaning, increased energy production as a result of this cleaning, and the inevitable re-soiling of the laminates over time once they have been cleaned.
• In the event that the solar modules need to be cleaned then clean the module use a soft cloth together with a mild detergent and clean water. Take care to avoid severe thermal shocks which might damage the module by cleaning modules with water which has a similar temperature to the modules being cleaned.
• On large systems, the benefit of cleaning dirt and debris from the array is a trade-off between the cost of the cleaning, increased energy production as a result of this cleaning, and the time for the re-soiling of the modules after cleaning.
• If you are unsure whether the array or section thereof needs to be cleaned then first select an array string that is particularly soiled then
   Measure & record the inverter feed in current from that string
   Clean all modules in the string
   Measure the inverter feed in current again and calculate the % improvement from cleaning
   If the improvement is less than 5% then it is normally nor worth spending the expense on cleaning
• The above verification should only be carried out when the insolation is effectively constant (clear sky, strong sunshine, no clouds)
• The back surface of the module normally does not need to be cleaned but, in the event this is deemed necessary, avoid the use of any sharp projects that might damage the penetrating the substrate material.

 

[pollenface]

I would not do that. I use to clean my Oled TV screen with Windex and about a year later I noticed some odd dull patches in the screen when the TV was off. A quick search and later I found out that the glass is coated with a chemical to reduce glare. That coating is slowly melted by windex and other cleaners. Now I only use a damp cotton cloth to clean my new TV.
I have no idea if solar panel glass has a coating on it but from my own visual inspection I suspect that it does.

For LCD screens you should be using a specialized LCD screen cleaner and a microfiber cloth

 

[robby]

For LCD screens you should be using a specialized LCD screen cleaner and a microfiber cloth

Just be careful of which kit you use. I have found that some of the cheaper ones use diluted alcohol.
I was told that it is also a chemical that will damage the laminate.

 

[Simi 60]

Never cleaned the panels we have on the roof of our boat in the 5 years we have been out here
Rain works fine.
Panels are flat mounted
9 X 270w

 

[eXodus]

the system on my house is over 10 years old - but has a good steeper pitch - never cleaned it once.
Had the best yield in year 8
Sometimes in the spring it looks like yellow with pollen - but then a strong rain washes it all away.

I can see that there might be a dust issue in desert climates.

I wouldn't even use regular tap water - too much minerals which could build up over multiple washes.

Catch rainwater - or use distilled water.

 

[12VoltInstalls]

use distilled water.

A small (non-sudsy) amount of mild dish soap in distilled water followed by a squeegee is how glass should be cleaned.

Windex = ammonia, others use vinegar. Bases and acids on glass just don’t make any sense to me

 

[RCinFLA]

Panel surface contaminate attenuation is dependent on given location. In S. Fla. at certain times we get a lot of fine grit sand from Sahara desert blown over from Africa. Bird poop is bad for PV production. Seagulls are the worse.

Initially, RainX won't be a problem, but sun's UV will decompose it over time into compounds that can cause some attenuation. It can also be a 'fly paper' trap for dirt/sand particles.

Silicon PV panels do not use UV light. Most of their peak useable spectrum is mid to longer wavelength (yellow-infrared) of light spectrum toward ultra-infrared.

Wavelengths below about 0.4 um (blue light) the energy of photon is so high any knocked free electrons recombine quickly generating no power. Below about 1.1 um (ultra-infrared) the photon does not have enough energy to knock an electron loose from its bond.