Solar Impulse is on target to circle the world. Presumably Solar Impulse has the most current and efficient solar cells available, while those on the ISS range between 5 and 10 years old. How do the two different solar panel systems compare?


The efficiency of the panels on Solar Impulse is listed as 23%.

The panels on the ISS are much older than 5 and 10 years. The first array (Z-) was added in 2000, which implies a manufacture date of at least 1-2 years earlier. The remaining three sets were added in 2006, 2007, and 2009.

The ISS Panels get about 14% efficiency, which was pretty good when they were manufactured.

A good chart listing solar cell efficiency's as available for home installation, is available here. A screenshot of the table is below.

Home Solar Cell Efficiency

Thus Solar Impulse seems like it has much better arrays. Of course they are not space rated, which is a very different design (exposure to atomic oxygen, weight, etc).

The Russian Mir space station had an array on Kvant-1 with 12% efficiency but dropped to 5% at the end of life.

  • $\begingroup$ It's a bit apples to oranges, because the efficiency of the ISS panels is relative to the the light available in space, whereas the efficiency in solar impulse is relative to the light available in the atmosphere. The latter has a much smaller spectrum, so it is easier to make efficient cells. $\endgroup$ Jun 30 '15 at 0:39
  • $\begingroup$ I'm surprised that the ISS panels are so inefficient. Since mass is at much more of a premium than dollars in spacecraft, usually advanced triple-junction solar cells are used with efficiencies from 27% to almost 30%. $\endgroup$
    – Mark Adler
    Jun 30 '15 at 1:03
  • $\begingroup$ @MarkAdler An interesting question to be asked! And not like they skimped on ISS construction. Though they are 15+ years old in design at this point. $\endgroup$
    – geoffc
    Jun 30 '15 at 1:04
  • $\begingroup$ I was under the impression the ISS solar arrays were flexible (they were rolled up for their transport to the ISS). Maybe triple-junction cells can't be manufactured like that? $\endgroup$
    – Hobbes
    Jun 30 '15 at 6:47
  • 1
    $\begingroup$ Geoffc's list is of commercially available panels for home installation, not space-rated panels. $\endgroup$
    – Hobbes
    Jun 30 '15 at 6:49

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