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RevI

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Reply with quote  #1 
We all know that PV's can convert a % of the sunlight falling on them. I want to know what happens to the rest of sunlight? Is is absorbed by the cell and radiated as heat or being reflected back.

stmbtwle

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Reply with quote  #2 
Both. Some is reflected by the glass, the rest is reradiated.
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RevI

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Reply with quote  #3 
Thanks for the reply. Question is, how much is reflected and how much is radiated?
stmbtwle

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Reply with quote  #4 
That I don't know. I know there are treatments to reduce reflection (capture more energy), and other materials to INCREASE radiation in the IR spectrum (helps with cooling), but all of these of course increase cost.

https://www.reddit.com/r/askscience/comments/1qgvs4/how_much_energy_is_lost_from_reflection_on_solar/

Once you determine the energy reflected, and the energy converted to power, the remainder must be dissipated somehow. If not, the panel temperature will increase until it reaches equilibrium. In a vacuum this would have to be radiation. In practice a lot of it is transferred to the surrounding air. Fan-cooling helps, but of course it increases cost and consumes energy. Same with water cooling.

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Rick H Parker

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Reply with quote  #5 
Most of what is not converted to electricity is converted to heat, one can tell that from the dark color.
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Rick H Parker
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RevI

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Reply with quote  #6 
There are many reasons behind this dark colour. At the initial stage, reflection from solar cell has been considered a menace and it often creates problems to neighbours. That's why at present special glasses are used to disperse the reflected light. I am curious to know what happens at the power conversion interface.
Rick H Parker

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Reply with quote  #7 
There are many reasons behind this dark colour.

Black is the absent of light .... the darker the shade the less the light.

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Rick H Parker
Kansas, USA
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RevI

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Reply with quote  #8 
Exactly that's what I want to mean. Dark colour doesn't necessarily mean that the reflection is less. It can be done by dispersing the reflected light. As I have already mentioned that reflection from solar cell has created enough menace for neighbours even a few years ago.
Rick H Parker

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Reply with quote  #9 
Dark colour doesn't necessarily mean that the reflection is less.

If the reflection is not low, how could it be dark ... you got the logic inverted.

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Rick H Parker
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stmbtwle

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Reply with quote  #10 
I do not see how reflection from a solar array could be a "menace" to your neighbors, unless they are flying around in a helicopter.  I guess it's possible with an east or west facing array but any reasonably installed array will reflect light up into the sky. After all, the whole object of a solar installation is to CATCH the sun, not reflect it.  Are you sure these neighbors aren't just the local homeowners association trying to "create" a problem?  Do they have actual photos or is this hearsay?

https://www.scientificamerican.com/article/solar-panel-boom-pits-neighbor/

Transmissivity of clear glass is around 90%, so you might expect 10% to be reflected. At very oblique angles, it would be more.  However as any solar energy that is reflected is lost (and reduces efficiency), you can bet that panel manufacturers do their best to prevent it.  Most panels have textured glass to reduce reflection, some even have non-reflective coatings.

A reflective surface can APPEAR dark if the energy is reflected away from the viewer, such as your headlights on a wet road at night.  That's one of the main concepts behind "stealth" technology.



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Solar is like the wind. It may be free, but putting it to work isn't!
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