Solar Panel & Hail Resistance / Damage
Solar Panels are designed to sustain a 5cm Diameter hail stone at terminal velocity otherwise they will fail IEC61730.
Solar panels are extremely strong and will withstand most hail. Quality panels are manufactured with tempered glass (similar to vehicle windscreens). Amorphous panels generally do not use tempered glass, and are more susceptible to being shattered by hail.
Most panels use 3 to 4mm thickness tempered safety glass and some are even certified for up to 28mm diameter hail at 86km/h - which, in most cases, is stronger than ceramic roof tiles. There have been cases where roof tiles have been hail damaged, yet the solar panels remained intact (along with the tiles beneath them!).
Significant hail larger than golf balls will damage panels. The only way to protect your investment is insurance. After a solar power system is installed, your insurance company must be notified as solar panels are not usually covered by standard house and contents insurance policies.