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Some answers on this site claim that the ISS US Segment solar arrays are double-sided (i.e. cells on both sides of the blanket). I tend to doubt this, but a search of my references did not turn up anything authoritative.

enter image description here

This image from the solar array repair EVA performed on STS-120 seems to show that the faces of the array are not the same (cropped from here). It is difficult to obtain images that show both sides of the array at once.

I seek an authoritative answer with solid documentation reference(s) that explicitly states one way or the other. NASA or contractor documentation, preferably.

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    $\begingroup$ To comment on the picture, you're looking generally at the back side of the array, seeing the backs of the cells (which are green) through the orange blanket coverlay, which is made from Kapton and fiberglass. The front side of the array is visible near the tear and features the glass-covered solar cells, which look either blue or black depending on viewing angle (due to the antireflective coating on the coverglass). $\endgroup$ – Tristan May 29 '17 at 18:41
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Having worked extensively on the solar arrays over the last five years, I can say they do receive about a third of their power from albedo exposure to the back side.

This is further confirmed from a "funny" I noticed in 2014 when doing testing on ISS solar cells. When trying to measure a solar cell's illuminated short-circuit current, I measured a value two and a half times what I expected. I soon discovered that I was not controlling the reflection of light behind the cell. Placing the cell in front of some black felt brought the measurements back in line with expectation.

Unfortunately none of the design documentation I am aware of is public. Unless someone here knows of something that has been released, I don't think you'll find authoritative confirmation beyond the assertions of individuals familiar with the hardware.

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  • $\begingroup$ So there are cells only on one side, but their backs are not opaque, allowing some power generation from light hitting the other side of the array? $\endgroup$ – Organic Marble May 29 '17 at 18:58
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    $\begingroup$ The cells are exceedingly thin (when retracted, the entire blanket stack is just a few inches tall), but that's not why they can get backside power. Both faces are doped to make them active. The blanket material is translucent and allows light to reach the back side of the cells. $\endgroup$ – Tristan May 29 '17 at 18:59
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    $\begingroup$ If you ever make it to the JSC visitor center, they have a segment of the solar array on display. Unfortunately I do not have photos available. $\endgroup$ – Tristan May 29 '17 at 19:04
  • $\begingroup$ What you say agrees with some vague statements I saw in the references I have, so I am going to accept. Thanks for clearing this up. $\endgroup$ – Organic Marble May 29 '17 at 19:05
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    $\begingroup$ They're aligned with the sun. Anything they get from the earth is a bonus. The one third figure is an average. $\endgroup$ – Tristan May 29 '17 at 19:51

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