diy solar

diy solar

Painting panels black

One would have thought that dark vs light color of a material would matter when it comes to absorbing the thermal energy of the sun but inconsequential when it comes to dissapating thermal energy in the shade.
 
BiduleOhm said:
The problem would be the thickness of the vinyl as it's a very poor thermal conductor. Ideally you want something really thin (and paint is), and if it's a good thermal conductor that's a bonus.
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Vinyl doesn't have a fixed thickness, though you can obviously spec your vinyl to your thickness requirements. Nor does paint have constant thickness, and can include a wide variety of chemical compositions. Paint is far less uniform and thus even more challenging to spec. Have you used car wrap?
 
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offgriddle said:
No science is required to naturally be aware of the phenomenon that the darker colors tend to have a higher solar thermal absorbance, one can ascertain this simply by being alive. How again is painting the solar panels & framework the darkest, most thermally absorbant colour in the visual spectrum going to be less thermally absorbant and/or reflective? If there's new data on the subject I'm all ears. Thank you.
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I'm not commenting on painting the aluminum framework black. I'm referring to painting the white backing sheet black (OP had done that). I really hope he did not paint the front of the panel black:)
Despite the fact it looks white (in the visible spectrum), and hence, should reflect heat, the plastic backing is a good absorber/reflecter of heat in the IR region. A panel that is 50-75 C in temperature radiates mostly in the mid & long range IR. In that spectrum, the Tedlar backing sheet is a good absorber/radiator. Painting it black is not going to make more "black" in any significant amount and increase the amount of heat it radiates.
 
ghostwriter66 said:
Forget the thermodynamic stuff - my question is - EXACTLY how did painting the BAVK of panels on a ROOF make anything more stealthy???
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I mounted my panels to a roof rack (which is black) to avoid drilling holes in the roof. The panels sit above the roof line about 8 inches so the underside of the panels being white was very obvious and stood out. After painting the backs they look like part of the rack and it’s hard to notice they are there. I should have mentioned the reason I did it.
 
offgriddle said:
You know I was thinking the same thing GW but I didn't dare to ask! Maybe when his van is stationary he tilts them so that the white undersides are exposed and visible to people on the ground?
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I mounted them to a roof rack that is black. They sit about 8inches off the roof. the white backing stood out too much so I painted the back black to look more like part of the roof rack. A tilt might be in the works eventually too though.
 
What paint did you use?
Will the black paint you used damage or react with the white plastic backing material on the panel or overheat the cells?
Let us know after they bake in the upcoming hot summer.
 
MBR said:
What paint did you use?
Will the black paint you used damage or react with the white plastic backing material on the panel or overheat the cells?
Let us know after they bake in the upcoming hot summer.
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Just spray paint and yes I will I’m trying to figure this out. It doesn’t seem like there are any definitive answers about this
 
Just watched the new 'The Invisible Man' last night, have you considered capturing video of the sky then projecting that onto the underside of your panels - the ultimate 'stealth'.
 
tictag said:
Just watched the new 'The Invisible Man' last night, have you considered capturing video of the sky then projecting that onto the underside of your panels - the ultimate 'stealth'.
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Shhhh... that's going to be my super secret new rec room ceiling.
 
Captain Gnarkill said:
It’s dark out so all I have is this picture for now, I’ll take one of the underside view tomorrow
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Hey, nice rack!!!
That shovel is not very stealth or aerodynamic!
Why don't you want people to see the white and think solar panels? Theft?
There is spray paint made for plastic so did your spray paint adhere properly on that slick backing?

1585589982376.png
 
MisterSandals said:
Have any pix?
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here’s a pick of the underside, looks a little cleaner and blends in better that the bright white.
Still trying to figure out if there is any real downside other than possible 5% less efficiency, maybe. Super thankful for all the comments, but no one is certain of any ill effects on the panel. In a way this is kinda good news.
 

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MBR said:
Hey, nice rack!!!
That shovel is not very stealth or aerodynamic!
Why don't you want people to see the white and think solar panels? Theft?
There is spray paint made for plastic so did your spray paint adhere properly on that slick backing?

View attachment 9938
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shovel is on a removable mount, I really like it because it’s fast to remove when I need it or to store in the van when I’m in town. Back to the panels... I used good ole’ black spray paint and has been holding up no problem. Any thoughts on the downsides to this hazard wise or in the efficiency?
 
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