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.
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.