how the hell do you make a solar panel catch fire? bad wire connections?
Your guess is as good as mine - electical fires would be an obvious risk with any solar-electric device, but chemical and/or simple thermal ignition might be hazards, as well.
On a somewhat related topic, it can be entertaining to do an internet search for images of "wind generator fire". Renewable energy "ain't all that it's cracked up to be"...
;^)