How are solar panels protected from the Sun?

Question

In 2003, JAXA sent a probe, Hayabusa, to an asteroid named Itokawa. On the way to the asteroid, there was a large solar flare which damaged the probe's solar cells. I've been searching through the site here, and I've found a couple of similar questions related to protecting astronauts from solar flares and even the impact of dust on solar panels, but I haven't found anything about the damaging effects of the Sun on solar panels.

I imagine there will be different methods in different circumstances (for instance, low-earth orbit vs geostationary orbit vs out of Earth's orbit), but what are some of the ways that the Sun can damage solar panels, and what do space agencies do to try to protect them?

Answer 1

Radiation from the Sun does indeed cause solar panels to deteriorate over time, and powerful single events can lead to a sudden reduction in the efficiency of a solar panel. In 2003, a large solar storm led to an average 3% drop in power for all of EUMETSAT's geostationary spacecraft.

We don't really have a good way to "protect" panels from such effects, and indeed degradation rates are of key interest on the ground as well as in orbit. The National Renewable Energy Laboratory published an in-depth analytical review of the issue a few years ago.

Since we cannot prevent the radiation from striking the solar panels, panels have to be built in such a way that they are resilient to the effects of radiation damage. That last link is far more comprehensive than I can be here, so I'll just let you go read that if you want to go deep into the science :)