diy solar

diy solar

Water repellent coating for solar panels

Hi luisenriquereyes

I use a product sold in the UK called RainX, it's essentially isopropyl alcohol. It's main use is for car windscreens, but I occasionally clean my solar panels with it. The rain just runs of the panel in beads. But if you have flexible panels don't use it as it can damage plastic, they even advise not using it with solar panels (I think their concern is with any plastic on the panel). I've used it it for years cleaning tape heads to the car and house windows and it evaporates very fast. Use it in a well ventilated area.

Rain on Solar Panel 22-09-2019.jpg
 
Interesting idea!

The effectiveness also probably depends on the panel's tilt (I noticed in the video the drops adhered even when he had the glass at 90). See in Johnny's photo how it's beaded up on a flat panel? I bet that hurts, the drops will take longer to evaporate and they'll collect dirt from the air. Be nice to know if a hydrophillic coating was better for flat panels.

Here's a video on a Hydrophillic Coating (Instead of beading up, water flattens down)

Found a paper on it:

We investigated the fabrication of large-area (cm2) nanostructured glasses for solar cell modules with hydrophobic and hydrophilic properties using soft lithography and colloidal lithography. Both of these techniques entail low-cost and ease of nanofabrication. We explored the use of simple 1D and 2D nanopatterns (nanowires and nanocones) and the effect of introducing disorder in the nanostructures. We observed an increase in the transmitted light for ordered nanostructures with a maximum value of 99% for wavelengths >600 nm when ordered nanocones are fabricated on the two sides of the solar glass. They produced an increment in the efficiency of the packaged solar cell with respect to the glass without nanostructures. On the one hand, the wettability properties showed that the ordering of the nanostructures improved the hydrophobicity of the solar glasses and increased their self-cleaning capacity. On the other hand, the disordered nanostructures improved the hydrophilic properties of solar glasses, increasing their anti-fogging capacity. The results show that by selecting the appropriate nanopattern, the wettability properties (hydrophobic or hydrophilic) can be easily improved without decreasing the efficiency of the solar cell underneath.
 
Here's a video on a Hydrophillic Coating (Instead of beading up, water flattens down)
Wow, that's quite impressive, looks to be very effective - I wonder if any solar panels are being sold with that coating on? They should also use that technology on the inside of my Tomato Ketchup bottle, I can never get the last bit out.

John
 
This is brilliant. I use RainX on my windshield and I buy the RainX impregnated wipers, and that is an amazing product. You can skip the wipers for the first couple months after application-the water just falls off.

What is the surface of our panels? Tempered glass?
 
Just a FYI, I used to use Rain-X on my car, but found a MUCH better product. The Rain-X would only last a couple weeks before it didn't repel water nearly as well as when first applied. I found a different product called Aqua-Pel that works as well as Rain-X, but lasts around a year between applications...MAJOR difference in lifetime. You can get it online at Amazon or eBay.

 
Any of you guys going to try this? take two panels side by side, coat one and measure twice?

... They should also use that technology on the inside of my Tomato Ketchup bottle, I can never get the last bit out.
Gravity is your friend, leave the bottle upside down in the fridge. ? (thanks for posting that video)
 
I recently had a hydrophobic coating applied to my roof, 6% grade (Henery Tropicool). It's interesting in that the water flows off it very differently now. Previously it would "sheet" to the edge and drip off in small drips (no gutters, drip strips), Now it's like Johnny's video, drops combine and I get more of a waterfall effect. Oddly, after a rainstorm the roof has more water not less than before, thousands of big drops that are too afraid (hydrophobic after all) to move. It's like the hood of a freshly waxed car vs an unwaxed car after a rainstorm.
 
Anyone know if hydrophobic or hydrophilic coatings work for frost/ice?
Try using plain automotive wax, however I don't know how this will affect the panels efficiency. When buffed, wax LOOKS clear, but I don't know the exact wavelength PV panels need to be most efficient. I do know that some window glass for houses blocks some type of the sun's rays and may impact PV panel efficiency.

You might also try heating the panel to about 40F to make any snow melt off it, but heat uses a lot of power.

Stores sell all kinds of heating cables for outdoor use. My idea would be to put the heating cables on the back of the panel.
 
Ran across a fairly new paper that looks at hydrophobic vs hydrophyilic coatings for mirrors (figure panel surfaces are fairly similar):

The anti-soiling (AS) performance of highly reflective, superhydrophilic (SPH, 0° water contact angle) coated mirrors was characterized and compared with that of superhydrophobic (SP, >165° water contact angle) coated mirrors. A simple one-step nanotextured silica nanoparticle coating on a mirror exhibited SPH properties associated with hydrophilic rough surfaces. Another mirror surface post-functionalized with low-surface-energy ligand molecules displayed SP behavior. Both coated mirrors, with no solar reflectance loss, demonstrated excellent AS performance because the engineered surface roughness reduced the adhesive force of dust particles. The daily degradation in solar reflectance induced by dust accumulation under outdoor field testing demonstrated that the SPH- and SP-coated mirrors, compared with an uncoated mirror, maintained higher solar reflectance, which was associated with the designed self-cleaning behavior and natural cleaning. However, over the long term, dust-moisture cementation—evidenced by organic hard water stains on the mirror—initiated unrecoverable reflectance loss on the SP-coated mirror after 3 months, whereas the SPH-coated mirror maintained higher reflectance for 7.5 months. Considering fabrication costs and maintenance, SPH-coated nanotextured mirrors offer potential benefits for application in solar energy harvesting.
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Conclusions
Facile and environmentally friendly silica oxide NP-textured coatings revealed excellent AS and unique self-cleaning performance associated with superhydrophilicity. The engineered surface roughness associated with superwetting significantly decreased the adhesive force of dust particles on a mirror surface, resulting in an intrinsic repellence of inorganic soil and dust particles and enhancement of self-cleaning behaviour due to facile water layer sliding. Compared with the AS performance of SP coatings, the SPH coating exhibited an ∼2.5 × enhancement of AS performance in outdoor field testing. Superhydrophilicity was more effective in reducing organic dust-cementation soiling on the mirror surface. Considering the fabrication process, cost, and extra energy-intensive cleaning cycles, SPH NP-textured coatings are expected to result in highly efficient solar energy harvesting.
 
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Ran across a fairly new paper that looks at hydrophobic vs hydrophyilic coatings for mirrors (figure panel surfaces are fairly similar):

The anti-soiling (AS) performance of highly reflective, superhydrophilic (SPH, 0° water contact angle) coated mirrors was characterized and compared with that of superhydrophobic (SP, >165° water contact angle) coated mirrors. A simple one-step nanotextured silica nanoparticle coating on a mirror exhibited SPH properties associated with hydrophilic rough surfaces. Another mirror surface post-functionalized with low-surface-energy ligand molecules displayed SP behavior. Both coated mirrors, with no solar reflectance loss, demonstrated excellent AS performance because the engineered surface roughness reduced the adhesive force of dust particles. The daily degradation in solar reflectance induced by dust accumulation under outdoor field testing demonstrated that the SPH- and SP-coated mirrors, compared with an uncoated mirror, maintained higher solar reflectance, which was associated with the designed self-cleaning behavior and natural cleaning. However, over the long term, dust-moisture cementation—evidenced by organic hard water stains on the mirror—initiated unrecoverable reflectance loss on the SP-coated mirror after 3 months, whereas the SPH-coated mirror maintained higher reflectance for 7.5 months. Considering fabrication costs and maintenance, SPH-coated nanotextured mirrors offer potential benefits for application in solar energy harvesting.



It looks like RainX and Aquapel are NOT superhydrophilic (SPH). What commercially available protects are SPH?
 
Hey @ghostwriter66, I don't suppose you all use coatings (either hydrophobic or hydrophillic) on your farm? If so, any data on them?
 
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