Golf Balls are Worse Than Hail Stones

Solar module manufacturers frequently state that modules can withstand falling hail up to 1-inch diameter, and infer that they also can withstand a golf ball hit. That is generally not a valid corollary.  Golf balls travel at twice the speed, are worse because they weigh six times more than a 1-inch hail stone and have 57 times more energy.

•  Hail stones only falls at speed between 25-40mph, and weighs o.26-oz. Energy is 1.26 joules
• Golf Balls fall at 72mph, and are 1 3/4 inches diameter, weighing 1.6-oz. Energy in a golf ball is 71.6 joules.  It is tremendously higher due to the rate of spin. Golf balls are designed to spin in order to travel further.
• Baseballs fall at 74mph, and are 2.75 inches in diameter, weighing 5.25-oz. Energy in a baseball is 225 joules.
• Rugby balls fall at 30mph, and are 10.8 inches in long, weighing 2.2lbs. Max average energy in a rugby ball is 900 joules.

The energy of a falling object is related to many factors. Different items fall at different speeds, have different weight, and may have spin as they travel (forward spin increases energy content and the damage they cause are worse than hail stones)