I've been thinking about some sort of protection also. I lost 2 out of 8 panels about two years ago to baseball sized hail. People in the area lost new cars, pickups and roofs. I still feel fortunate.
Here's a few of my 'might work' ideas:
1. large hole chicken wire mounted about 4 feet from the panels. That should offer enough bounce to take out most of the energy. Think trampoline.
2. frame mounted panels that can rotate upside down to expose a convex shape of 1/8" steel fixed to the panels' back. That might offer wind protection also.
3. Sun Tuff greenhouse panels mounted a foot or so away from the panels. Gary over on build it solar has some data on them.
http://www.builditsolar.com/Experimental/GlazingTransmittance/GlazingTransmittance.htm He got 0.89 light transmittance on the polycarbonate. That wouldn't hurt too bad for the protection it affords. ?
4. Some insurance policies offer protection as a rider to the homeowner's policy.
I could use some new ideas to consider too. I'm still in the building phase of my new container house and the solar panels will be one of the last items to be relocated. In the meantime, they are in use furnishing power for everything that uses 120 VAC, including air conditioning. I really don't want to loose any more panels.