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I am a grade six student at Sir William Osler elementary, in Vancouver, British Columbia, Canada. This school term I will be conducting a scientific experiment for my class science fair. The topic I have selected is regarding the productivity of solar panels under different so-called “filters” of light. Such filters are transparent plastic sheets colored red, yellow, and blue. In my current project, I will be testing the productivity of my solar cells under such circumstances. The experiment will be carried out in 10 to 15 trials in the next three weeks.

I am writing this letter of inquiry in hope that I may have the opportunity to ask you several questions pertaining to my project as I have found it is in your area of expertise.

Is it possible that different silicon compositions could make two-axes oriented arrays more efficient? Possibly any theoretical work yourself may have done?

Question Date: 2017-10-15
Answer 1:

This is fundamentally a materials problem.​ T​he most efficient form of a solar cell ten​​ds to be single crystalline​, which minimizes defects and impurities that could cause the carriers in the solar cell to recombine. Even then the maximum theoretical limit (see Shockley Queisser​ limit ) is less than 35% efficiency.

Silicon itself is intrinsically ​inefficient due to its electronic structure​ (it has an indirect band gap)​. However, because it's ​
2)​abundant​, and
3)so well understood as a material​, it's a difficult material to out-compete​ economically.​

Nevertheless, a lot of effort has been made to work around this theoretical limit (which relies on several assumptions).

You can read about it here and a pretty cool example here .

You can also see a nice compilation of efforts to improve solar cell efficiency around the world with silicon and other materials here .

​But there are other factors that come into play, such as toxicity, cost, ease of growth and processing.

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