Solar panels are designed to withstand severe weather, including hailstorms, and are tested to endure hailstones up to 1 inch in diameter at speeds of 50 mph. However, extreme hail can still cause damage. . Historically, solar photovoltaic PV modules have survived the majority of hail events they have experienced. In areas that have experienced very large hail (greater than 1 ¾" or 44 mm diameter), however, hail has caused significant damage to PV modules. Some measures can be taken to limit damage to. . Glass thickness is the critical protection factor: Research confirms that 4mm glass panels significantly outperform the standard 3. The verdict? Most panels emerged unscathed, proving that today's solar technology can take a serious beating.