Lets start off by mentioning that our oldest system was put in back in 2011 and today almost 2018 we have not had any solar hail damage claims to date. Now we have had to pull the panels off the roof of a hail damaged roof for an insurance re-roof type scenario on two separate occasions, but those panels were not damaged at all.
One thing to consider when hail is coming down, it is not striking the panel at a direct 90 degree angle hit, most panels are set at about a 20 to 30 degree tilt on average. Some of that inertia coming down is directed downward based on the tilt of the panel.
The Industry standard is for a solar panel to withstand a a golf ball sized hail stone at 50mph, however as you will see in the video presented to you by Solar World USA the solar panels are much more resilient than that. https://youtu.be/M6v2lDa8Hos
Solar and Generator Division Coordinator