Depends on where you live. For most areas of the United States, hail is infrequent and pebble-sized, and unlikely to do any notable damage to the panels. However, in places where hail is frequent (i.e. at least 1x per year) and highly damaging (i.e. golf-ball-sized hail that can leave bruises on a passerby, put cracks in windshields and damage rooftops) it's a big enough concern that I would advise against a solar install unless you can consistently predict hail and adequately protect them.