Does anyone use anything like Rain-X on their panels?

[russ]

I suppose a hypothesis has to start with a single test case before a larger scale and more scientific experiment can be performed. Keep us updated with your experience.

Dawn - Something like this would have to be done under very controlled conditions - which are very difficult to do out of doors - not to mention who has the necessary equipment starting with a pyranometer.

While results may be of general interest they are pretty much meaningless.

[Dawnweaver]

I suppose a hypothesis has to start with a single test case before a larger scale and more scientific experiment can be performed. Keep us updated with your experience.

[russ]

But so far my conclusion is that the Rain-X probably helps, but in a very small way.

Boy but that is one scientific conclusion! Peer reviewed by three ants and a fly?

[SunEagle]

Yesterday I ventured back up to take a look. It's been at least a month since I cleaned all panels and re-applied the Rain-X to just one of them. What I could see if that there is a marginal difference. The Rain-X panel seemed to have a little less rain residue/dust/dirt on it. It's a small but noticeable difference which I think would get bigger with time. How much difference it would make to the efficiency of the panels I have no idea. But as I can't see any immediate downside I took the opportunity to put Rain-X on all the panels. I'll let you know if I experience anything negative. But so far my conclusion is that the Rain-X probably helps, but in a very small way.

Thanks for experimenting with the Rain-X.

Just keep an eye on any gasketing or sealant around the panel frame to see if there is any breakdown and water intrusion due to a chemical reaction.

[russ]

You can get a cheap ($200-ish) thermal camera attachment for a smartphone. Not as accurate or fancy as a dedicated unit, but good enough to find hot spots on your panel. Plus way fun to play with. The model I bought is called Seek Thermal, and is readily available on Amazon.

Thermal cameras in the hands of a newbie give useless temperatures. They provide more useless data than possibly any other measuring device on the market. Emissivity is the key part and most have no idea what the word means.

[solarix]

I tried Rain-X a few years ago just like you. Had some left over from a previous life so always being curious.....
My conclusion (without any objective tests) was that it was detrimental if anything. Actually seemed to make the glass a little sticky so stayed dustier. The difference with PV panels is you don't have a wiper to do the cleaning. Also suppose the Rain-X might interfere with the anit-reflective coating on the glass.

[pamalot]

Yesterday I ventured back up to take a look. It's been at least a month since I cleaned all panels and re-applied the Rain-X to just one of them. What I could see if that there is a marginal difference. The Rain-X panel seemed to have a little less rain residue/dust/dirt on it. It's a small but noticeable difference which I think would get bigger with time. How much difference it would make to the efficiency of the panels I have no idea. But as I can't see any immediate downside I took the opportunity to put Rain-X on all the panels. I'll let you know if I experience anything negative. But so far my conclusion is that the Rain-X probably helps, but in a very small way.

[J.P.M.]

So, I went up there and took a look this morning. The panel that has the Rain-X on looks noticeably cleaner than the other panels. However, I came to the conclusion that it's probably because I cleaned that panel before I put the Rain-X on and I didn't clean the other panels. So I've just re-set the whole experiment again and washed ALL panels clean this time. I'll go back up there in a month and see if I can see a difference.

Thanx for the info. I'll be interested to see what happens. I'd suggest keeping in mind that the human eye is not the best tool to gauge the effects of dirt and its effects on solar equipment performance.

[pamalot]

So, I went up there and took a look this morning. The panel that has the Rain-X on looks noticeably cleaner than the other panels. However, I came to the conclusion that it's probably because I cleaned that panel before I put the Rain-X on and I didn't clean the other panels. So I've just re-set the whole experiment again and washed ALL panels clean this time. I'll go back up there in a month and see if I can see a difference.

[zaki]

I suspect that they were also concerned about the effect on the sealant at the edge of the panels because:
1. They did not test with sealant compounds other then those used for automotive glass panels.
2. They did not take into account the fact that the solution could pool at the edges of the panels during application, something that would not happen with typical auto glass sealant systems.

They did not take into account the fact that the solution could pool at the edges of the panels during application, something that would not happen with typical auto glass sealant systems.
I think so, this is an indisputable fact






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[J.P.M.]

I'm not sure what the relationship would be, if any, between a panel's local temp. and any change in the surface reflectivity of the glazing. So, while a thermal camera may very well show a temp. diff., I'm not sure how such a temp. diff. would be interpreted.

Off the top of my head, a few of probably many considerations:

If the reflectance was changed by the Rain-X, and that change was to decrease the reflectance in the PV sensitive wavelengths, or even out to the IR, that may be a good thing by increasing the amount of sunlight getting past the surface. However, that would then increase the absolute amount of radiant energy trying to penetrate the glazing which would increase the amount of energy absorbed by the glazing, probably increasing its temp.

If the Rain- X were to increase the reflectance in those same wavelengths, the glazing temp. may drop as less energy is absorbed.

Meanwhile, if the Rain-X increases reflectance in the IR, an IR thermometer would need an (unknown ?) emissivity adjustment to avoid a false reading.

If the Rain-X keeps things cleaner, the glazing will tend to be warmer.

Etc.

[SunEagle]

You can get a cheap ($200-ish) thermal camera attachment for a smartphone. Not as accurate or fancy as a dedicated unit, but good enough to find hot spots on your panel. Plus way fun to play with. The model I bought is called Seek Thermal, and is readily available on Amazon.

I saw that advertised. It would be interesting to compare it to a more accurate thermal camera but with this application you don't need to know the temp within a couple of degrees F. You just need to see if there are spot or areas of different heat emission.

Let us know what you find out with your camera.

[pleppik]

Another tool that may detect something the "eye" doesn't would be an Infrared thermography camera. They are not cheap (~$1000) but may provide some thermal details about the panel surface.

You can get a cheap ($200-ish) thermal camera attachment for a smartphone. Not as accurate or fancy as a dedicated unit, but good enough to find hot spots on your panel. Plus way fun to play with. The model I bought is called Seek Thermal, and is readily available on Amazon.

[SunEagle]

My suggestion on one cell was so that if the Rain-X did affect the anti reflection coating, it might be a visible to the eye and would not be as bad an outcome as if a whole panel were coated. The Rain-X may affect the panel/coating in ways that may not be visible to the eye.

As long as an entire panel is coated, if you have a micro inverter system w/monitoring, consider monitoring the test panel and an adjacent panel.

FWIW, that's also one not too bad way to get a back of the envelope SWAG at panel/system fouling.

Another tool that may detect something the "eye" doesn't would be an Infrared thermography camera. They are not cheap (~$1000) but may provide some thermal details about the panel surface.

[J.P.M.]

I did one complete panel with Rain-X over the weekend. I thought, if I'm going up on the roof just to do one corner of one panel, it ain't worth it, so I did one complete one while I was up there. I plan on going back up there in a month and seeing if I can see any noticeable difference. What I'm gonna look for specifically is if there is any difference in the amount of surface dust/dirt between them. I'll keep you posted.

My suggestion on one cell was so that if the Rain-X did affect the anti reflection coating, it might be a visible to the eye and would not be as bad an outcome as if a whole panel were coated. The Rain-X may affect the panel/coating in ways that may not be visible to the eye.

As long as an entire panel is coated, if you have a micro inverter system w/monitoring, consider monitoring the test panel and an adjacent panel.

FWIW, that's also one not too bad way to get a back of the envelope SWAG at panel/system fouling.