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Quite a bit of the EM spectrum is filtered out by the Earth's atmosphere, which means there's less incident solar energy per area on the ground that in space. There's more discussion of that topic here:

What effects does atmosphere have on solar panels?

My multi-part question is:

  • Do solar panels designed to operate outside of Earth's atmosphere use those parts of the EM spectrum that don't reach the ground?

  • If they're NOT designed to capture those other parts of the spectrum, could they be?

  • Are there other known photovoltaic reactions in the infrared or UV that could in theory be exploited?

  • How much more electrical energy could be produced by doing so?

  • Does anybody have any online references with more detail about space vs ground solar panels?

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    $\begingroup$ There's some raw data in this answer, there's very little to worry about in the UV, and in the IR it becomes very difficult to find robust semiconductors that will do the conversion, though a solar-thermal system could potentially use the fraction of the IR that's blocked by the atmosphere. $\endgroup$ – uhoh Dec 6 '19 at 0:40
  • $\begingroup$ Look up any set of graphs showing the atmospheric absorption vs. wavelength, then convolve that with the exoatmospheric irradiance vs. wavelength and the collection efficiency (quantum efficiency) of solar panels, and you'll have your answer to reasonable accuracy. $\endgroup$ – Carl Witthoft Dec 6 '19 at 14:19
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    $\begingroup$ @CarlWitthoft That only helps if I assume the panels going into space as the same as the ones on the ground. $\endgroup$ – Jerry Guern Dec 7 '19 at 1:59
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I know other individuals will have better answers but I think I can cover some of what your looking for.

  1. Solar panels were initially used on satellites before being used on Earth due to their high costs. So they were initially developed for commercial use in space. (Ironically the first use on earth was on oil rigs.) So solar panels have always been designed and researched with use in space in mind.

  2. Additionally how much solar radiation hits the solar panel matters. A solar panel on the moon in sunlight is ~120% more effective than ideal conditions on the earth. This is due to the lack of atmosphere. The moon is also effectively the same distance from the Sun as the Earth is when comparing the distances involved, so this provides a good benchmark for how much the Earth's atmosphere interferes with solar power collection. Mars, despite a very thin atmosphere, has an ideal solar collectivity of ~40% due to its distance from the sun. So we won’t be using solar panels on Mars for colonization. Mercury is far closer and is super efficient though I don't remember those numbers.

Sadly I do not remember where I found the 120% information for the moon but 40% for Mars I saw here. Mars moonbase video

Edit: Cambridge University stated in a video at https://www.zero.cam.ac.uk/ that they are working to allow solar panels to use more of the sun's radiation. No idea if that means increasing the spectrum that works with panels but that might be a place to look.

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    $\begingroup$ I've adjusted the format slightly. I'm not able to see the view the video though: i.stack.imgur.com/rY6oZ.png $\endgroup$ – uhoh Dec 7 '19 at 23:10
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    $\begingroup$ Thank you! That's very helpful info. $\endgroup$ – Jerry Guern Dec 8 '19 at 18:45
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    $\begingroup$ Just to make absolutely sure, does '120% more effective' mean 1.2 x the effectiveness, or 2.2 x the effectiveness? $\endgroup$ – Ingolifs Dec 8 '19 at 18:55
  • $\begingroup$ --Ingolifs, I understood it as 1.2x $\endgroup$ – T.A. McKay Dec 8 '19 at 22:04
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    $\begingroup$ Here's a quick article on solar being used on oil rigs; it has to do with needing independent power for navigation beacons/lights, basically. $\endgroup$ – tedder42 Dec 11 '19 at 20:51

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