White solar panels

Are they more efficient, and if so, why aren’t they all white?

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White solar panels

#1  Postby mindhack » Jun 21, 2022 7:18 am

Just a quick question about solar panels.

I read that solar panels become less efficient when the surface gets too hot, so why are all the panels I see either blue or black, but never white?

Surely consumers would like more efficient panels. What am I missing here?
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Re: White solar panels

#2  Postby Spearthrower » Jun 21, 2022 7:26 am

Dark colours absorb more visible light (which is why they seem 'dark' to us as less light is bouncing away), whiter colours reflect more (more of the spectrum is scattered back out, being perceived as 'white'). The more light absorption in a solar cell, the better!

I also believe that the material structure of the panels which are naturally darker coloured are more energy efficient structurally additional to the better absorption of the darker colour.

Hold on, let me google the word I am looking for.... aha! A monocrystalline cell!

Blue panels are silicon cells, black panels are monocrystalline cells - these cells are substantially more efficient than silicon ones, but they're also substantially more expensive to make.
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Re: White solar panels

#3  Postby mindhack » Jun 21, 2022 7:38 am

So the panels actually have to absorb the radiation, hitting the surface won’t do it?
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Re: White solar panels

#4  Postby Adco » Jun 21, 2022 7:53 am

The photovoltaic effect relies on a photon striking an electron to produce an emf. Therefore, the absorbing material must have "direct" contact with the incoming light and not be reflected away.
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Re: White solar panels

#5  Postby Spearthrower » Jun 21, 2022 7:56 am

I'll defer to Adco who has a lot more practical knowledge on this than me, but yeah, in essence, they have to make contact - whatever that means on such scales! :)
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Re: White solar panels

#6  Postby Spearthrower » Jun 21, 2022 8:01 am

Stuff humans can do is insane.

https://en.wikipedia.org/wiki/Monocrystalline_silicon

Monocrystalline silicon is generally created by one of several methods that involve melting high-purity, semiconductor-grade silicon (only a few parts per million of impurities) and the use of a seed to initiate the formation of a continuous single crystal. This process is normally performed in an inert atmosphere, such as argon, and in an inert crucible, such as quartz, to avoid impurities that would affect the crystal uniformity.

The most common production technique is the Czochralski method, which dips a precisely oriented rod-mounted seed crystal into the molten silicon. The rod is then slowly pulled upwards and rotated simultaneously, allowing the pulled material to solidify into a monocrystalline cylindrical ingot up to 2 meters in length and weighing several hundred kilograms. Magnetic fields may also be applied to control and suppress turbulent flow, further improving the uniformity of the crystallization.[3] Other methods are zone melting, which passes a polycrystalline silicon rod through a radiofrequency heating coil that creates a localized molten zone, from which a seed crystal ingot grows, and Bridgman techniques, which move the crucible through a temperature gradient to cool it from the end of the container containing the seed.[4] The solidified ingots are then sliced into thin wafers during a process called wafering. After post-wafering processing, the wafers are ready for use in fabrication.

Compared to the casting of polycrystalline ingots, the production of monocrystalline silicon is very slow and expensive. However, the demand for mono-Si continues to rise due to the superior electronic properties—the lack of grain boundaries allows better charge carrier flow and prevents electron recombination[5]—allowing improved performance of integrated circuits and photovoltaics.
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Re: White solar panels

#7  Postby mindhack » Jun 21, 2022 8:06 am

Interesting. So there’s no way around in the case of colour at least, but what else can be done to prevent the panels from becoming too hot?

Surrounding them with plant material, like grass or moss, that could work. I don’t see that anywhere. Probably too tricky on rooftops, but why not integrate green in solar fields?

Oh and another thing. I saw a nature documentary once, about giraffes (made by the one and only famous Dave :) ) Amazingly giraffes keep their skin cool because how it is coloured. The dark spots warm faster than the lighter stripes, which causes a cooling airflow. I thought it brilliant design ;)

Perhaps solar panels can’t be white then, but what if they’d resemble a giraffe’s skin?

:)
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Re: White solar panels

#8  Postby mindhack » Jun 21, 2022 8:07 am

Adco wrote:The photovoltaic effect relies on a photon striking an electron to produce an emf. Therefore, the absorbing material must have "direct" contact with the incoming light and not be reflected away.

Thanks!
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Re: White solar panels

#9  Postby Spearthrower » Jun 21, 2022 8:32 am

mindhack wrote:Interesting. So there’s no way around in the case of colour at least, but what else can be done to prevent the panels from becoming too hot?

Surrounding them with plant material, like grass or moss, that could work. I don’t see that anywhere. Probably too tricky on rooftops, but why not integrate green in solar fields?

Oh and another thing. I saw a nature documentary once, about giraffes (made by the one and only famous Dave :) ) Amazingly giraffes keep their skin cool because how it is coloured. The dark spots warm faster than the lighter stripes, which causes a cooling airflow. I thought it brilliant design ;)

Perhaps solar panels can’t be white then, but what if they’d resemble a giraffe’s skin?

:)



My only consideration here is how difficult it might be to get giraffes onto your roof.
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Re: White solar panels

#10  Postby Adco » Jun 21, 2022 8:45 am

Spearthrower wrote:
mindhack wrote:Interesting. So there’s no way around in the case of colour at least, but what else can be done to prevent the panels from becoming too hot?

Surrounding them with plant material, like grass or moss, that could work. I don’t see that anywhere. Probably too tricky on rooftops, but why not integrate green in solar fields?

Oh and another thing. I saw a nature documentary once, about giraffes (made by the one and only famous Dave :) ) Amazingly giraffes keep their skin cool because how it is coloured. The dark spots warm faster than the lighter stripes, which causes a cooling airflow. I thought it brilliant design ;)

Perhaps solar panels can’t be white then, but what if they’d resemble a giraffe’s skin?

:)



My only consideration here is how difficult it might be to get giraffes onto your roof.

Especially if the roof was sloped. They would keep sliding off....
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Re: White solar panels

#11  Postby Fenrir » Jun 21, 2022 8:49 am

Growing Crops Under Solar Panels Could Substantially Boost Energy Production

As for the giraffes, you breeds em to have the legs on one side shorter than the legs on the other side. Simples. Up ere fer thinkin ay.
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Re: White solar panels

#12  Postby Adco » Jun 21, 2022 8:52 am

mindhack wrote:Interesting. So there’s no way around in the case of colour at least, but what else can be done to prevent the panels from becoming too hot?

Surrounding them with plant material, like grass or moss, that could work. I don’t see that anywhere. Probably too tricky on rooftops, but why not integrate green in solar fields?

Oh and another thing. I saw a nature documentary once, about giraffes (made by the one and only famous Dave :) ) Amazingly giraffes keep their skin cool because how it is coloured. The dark spots warm faster than the lighter stripes, which causes a cooling airflow. I thought it brilliant design ;)

Perhaps solar panels can’t be white then, but what if they’d resemble a giraffe’s skin?

:)
Any addition of a reflecting colour would decrease the efficiency of the panel.

Heat buildup on the panels is an unfortunate byproduct of the whole process. You could have a cooling fan of sorts but that would require power that has to come from somewhere thus decreasing the overall efficiency of the system. Perhaps a clever method of channeling the heat away using ducts and and vents is possible but I guess they would have done that already. They're clever people that try and think of everything.
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Re: White solar panels

#13  Postby mindhack » Jun 21, 2022 9:06 am


Agrivoltaics. Amazing! Never heard of it. And so many more benefits than solar efficiency too! 8-)
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Re: White solar panels

#14  Postby mindhack » Jun 21, 2022 9:08 am

So Adco, others, you don’t think I’m brilliant with my novel giraffe idea, eh? :lol:
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Re: White solar panels

#15  Postby Adco » Jun 21, 2022 9:22 am

mindhack wrote:So Adco, others, you don’t think I’m brilliant with my novel giraffe idea, eh? :lol:

Brilliant!
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Re: White solar panels

#16  Postby Spearthrower » Jun 21, 2022 10:54 am

mindhack wrote:Interesting. So there’s no way around in the case of colour at least, but what else can be done to prevent the panels from becoming too hot?


A thick canvas shading them from the sunlight should do it! :shifty:
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Re: White solar panels

#17  Postby mindhack » Jun 21, 2022 11:19 am

Spearthrower wrote:
mindhack wrote:Interesting. So there’s no way around in the case of colour at least, but what else can be done to prevent the panels from becoming too hot?


A thick canvas shading them from the sunlight should do it! :shifty:

Dude! I know something way better! Sunglass... :awesome:
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Re: White solar panels

#18  Postby Spearthrower » Jun 21, 2022 11:21 am

mindhack wrote:
Spearthrower wrote:
mindhack wrote:Interesting. So there’s no way around in the case of colour at least, but what else can be done to prevent the panels from becoming too hot?


A thick canvas shading them from the sunlight should do it! :shifty:

Dude! I know something way better! Sunglass... :awesome:


I'm sure the giraffes will feel cooler wearing sunglasses!
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Re: White solar panels

#19  Postby mindhack » Jun 21, 2022 11:57 am

No doubt. No doubt. Gets me thinking. They’ll probably start singing so cool they’ll feel. And we should harness that energy to provide us with entertainment and burglar security.
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Re: White solar panels

#20  Postby Fenrir » Jun 21, 2022 12:10 pm

Nix on the entertainment. If we encourage singing then next thing they'll be dancing. We should not encourage roof-giraffes to tap-dance.
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