Martin Gregorie wrote:
...
I'd like to add another thought: at my club we are taught to leave
canopies closed whenever the glider is unoccupied and unattended. If
you leave the glider for 5 minutes you still close the canopy. The
reasoning is to prevent canopy damage rather than to stop fires, but
from your observations I suspect that the closed canopy discipline
(and better - with the cover on if its sunny) will also prevent
solar-started burns and fires.
...

The same rule is in effect in my club. Furthermore, each glider has
a canopy cover which stays in the glider when not used, so if you leave
the glider for some time, you close the canopy and cover it.