The most common way is to simply cover them with a tarp or plastic sheeting when bad weather is forecasted. This will keep the majority of the water off of the panels and prevent any damage.
From solar-absorbing granite facades that help regulate indoor temperatures to photovoltaic-embedded limestone pathways that generate electricity, these innovations are transforming passive stone surfaces into active energy contributors.
Regularly check the surface of PV modules for dust, bird droppings, or obstructions, and clean them if necessary. Use an infrared thermal imaging camera to detect local overheating (hot spots).
Solar panels are rated for hail impact which is roughly the impact of a 1" hail ball striking the panel at 52 mph. The tempered glass protects the solar cells under this type of impact.