# Prism Design to Filter Out Infrared Light

#### Yachtsman

Is it possible to filter out infrared light using a prism, and if so, how? What is the math involved to do this?

I want to come up with some effective, durable ways to filter out IR light for solar panels, to keep their temperature lower to make them more efficient.

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#### TheOtherDave

Is it possible to filter out infrared light using a prism, and if so, how? What is the math involved to do this?

I want to come up with some effective, durable ways to filter out IR light for solar panels, to keep their temperature lower to make them more efficient.
I'm not sure there's any math involved at all. Just look at where the visible light ends and block off everything on either side of it. I'd lookup which frequencies your cell is the most efficient at first, though. It might like the IR light.

#### daqddyo1

You must choose the prism material carefully by researching the following:
1) What are the wavelenghts that the solar cells respond most stronly to.
2) What are the wavelengths transmitted by the prism material?
3) How much of the required light is absorbd by by your prism material?**
4) If IR is not beneficial to the power produced, try to chose a material that does not transmit IR.
I presume you are worried about the panels overheating from the IR absorption.

If I were doing this, I would skip the prisms (added cost and weight) and just go with an IR filter.

#### Claude Bile

A prism is not ideal because the angle of incidence and the position at which the light strikes the prism is inherently variable. This results in a plethora of spectra superimposed on one another which largely prohibits spatial filtering.

I agree with daqddyo1; a spectral filter is by far a simpler solution here.

Also, keep in mind that most glasses are not transparent below a wavelength of 2 microns in any case, so any prism would effectively act as an IR filter anyway.

Claude.

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