I've experienced a few small hail storms with no issue. In general, the panels will often survive better than other aspects of the trailer or tow vehicle. Here is a link talking about testing specs of panels
https://www.ul.com/inside-ul/solar-panels-testing/ with this being the tests:
"
There are two types of impact tests that UL conducts. The first is a historical impact test that measures impact toughness of PV modules. UL lab technicians drop a two-inch solid steel sphere from a height of 51 inches onto the surface of the PV module, the energy equivalent of a hail stone measured at one inch and three-eighths in diameter falling at terminal velocity through the sky.
The second impact test is a true hail impact. This “classic” test involves placing a perfectly formed spherical chunk of ice into a pneumatic cannon and firing the calibrated ice ball at 10 to 13 critical locations on the PV module. Most often, UL technicians will shoot 25-millimeter, or approximately one-inch, ice balls at the module at about 52 miles per hour."