Hail impact test

Hail impact test procedure – step by step:

1. Preparation of the test specimen

• The object to be tested (e.g. a PV module, window or car roof) is secured to a test bench.
• The ambient conditions (temperature and humidity) are documented.
• In some cases, the object is measured and checked for functionality beforehand (e.g. power output in the case of PV modules).

2. Production of hailstone

• Standardised ice balls are produced, e.g.:

                 Ø 25 mm (typical test value)

                 Ø 50 mm (extreme hail).

• The balls are made of clear water and are deep-frozen to simulate real hailstones.

3. Bombardment with artificial hail

The ice balls are fired at the object using an air pressure cannon.

• Typical impact speeds are 23–39 m/s, which corresponds to real hail.
• The bombardment targets critical areas (e.g. corners, edges and transitions) at defined intervals or in defined patterns.

4. After the impact test:

• The product is inspected for visible damage, such as cracks, dents, spalling and glass breakage.
• This is followed by a functional test:
  • PV modules: performance measurement and insulation test.
  • Windows undergo a leak test and an opening mechanism test.
  • Vehicles undergo a paint test and sensor function test.

5. Evaluation and classification

• Depending on the applicable standard, the product is considered to have passed if it meets the following criteria:
  • It shows no relevant mechanical damage.
  • Its functionality is fully preserved.
  • There are no safety defects.

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