Hail resistancefor solar modules explained simply
- Martin Schmal
- 2 days ago
- 5 min read
Hail resistance classes are based on the energy of the hailstorm, determined by its size, mass, and impact speed. While these so-called HW classes are occasionally mentioned as additional information in the PV industry, they are not mandatory for solar modules. HW classes do not replace IEC testing and have no relevance for approval, warranty, or electrical safety.
For solar modules: IEC testing is decisive and mandatory.
IEC = Mandatory for safety and comparability
HW = Additional information
A solar module can achieve HW5, but without IEC certification it would still not be eligible for approval. That's precisely why the IEC standard is the only truly decisive standard for the hail resistance of solar modules.
Criteria / Hail class and what they mean
Meaning | Practical example | |
HW 2 | Hailstones up to 20 mm, 3.6 grams, 19.5 m/s | This is insufficient for a minimum standard for PV modules. |
IEC module testing | Hailstones up to 25 mm ~7.5 grams 23 m/s | IEC 61215 is the mandatory standard that ensures reliable hail resistance for all solar modules. |
HW 3 | Hailstones up to 30 mm, 12.3 grams, 29.2 m/s | This is achieved by all common dual-glass PV modules with a glass thickness of at least 2 + 2 mm. |
HW 4 | Hailstones up to 40 mm, 29.26 grams, 27.5 m/s | This is achieved by all common glass-foil PV modules with a glass thickness of at least 3.2 mm. |
HW 5 | Hailstones up to 20 mm, 3.6 grams, 19.5 m/s | This is achieved by dual-glass PV modules with a glass thickness of at least 3.2 + 2.0 mm. |
The hail classification is determined by glass thickness and module construction.
Glass thickness | Construction | Classification | Market share DACH approx. |
1.6 mm + 1.6 mm | Dual-glass | IEC 61215 | 12% |
3.2 mm | Glass foil | HW 4 | 13% |
2.0 mm + 2.0 mm | Dual-glass | HW 3 | 65% |
3.2 mm + 3.2 mm | Dual-glass | HW 5 | 4% |
4.0 mm | Glass foil | HW 5 | 1% |
The hail resistance class is a result of the construction, specifically the glass thickness and module design. If the design remains the same, the hail resistance class generally remains constant.
Why choose SOLYCO modules for optimal hail protection?
SOLYCO deliberately focuses on the two designs that represent the best technical and economic solution for 90% of all DACH projects :
2.0 mm + 2.0 mm Dual-glass - The industry-leading standard
3.2 mm glass-foil - The classic premium construction, lighter & more economical
This way, customers receive maximum protection at optimal weight and cost . Safety is achieved through design, not marketing. SOLYCO builds modules the way hail protection works in real-world situations.
Do you need a solar module of the HW 5 class?
We also develop special designs on a project-specific basis, but only where they really make sense.
However, for the majority of DACH projects, we recommend our dual-glass and glass-foil constructions , as they offer the optimal balance of hail protection, weight and cost .
Background information on hail resistance according to IEC
The basic minimum requirements for the hail resistance of photovoltaic modules are defined in the IEC 61215 standards.
Furthermore, the hail register of the VKF (Association of Cantonal Fire Insurers) serves as a generally recognized reference. It lists components that have been tested in accredited testing laboratories and thus provides reliable information on the hail resistance of individual products.
Important to know: Manufacturers are increasingly advertising extremely high hail resistance ratings. It's crucial to carefully examine whether these claims are based on certified tests. Without proof of testing by an accredited laboratory, such statements are often unreliable.
The hail register is particularly relevant for the construction industry, as it provides planners, installers, and manufacturers with clear guidance. Furthermore, insurance companies also place importance on enhanced hail protection for specific projects, as this reduces the risk of damage and can positively impact insurability or premium calculation.
FAQ
1. What does the hail resistance class (HW) mean for solar modules?
HW classes describe how much impact energy a component can withstand, based on hail size, mass and impact velocity. They originally come from tests for roofing and façade materials, not from PV module standards.
2. Are HW classes mandatory for solar modules?
No. HW classes are purely optional information. They are not required for the certification or approval of solar modules.
3. Which hail test is actually relevant for solar modules?
The only decisive and mandatory test is IEC 61215. Without passing the IEC test, no rooftop PV module can be sold or installed in the EU.
4. What exactly does IEC 61215 test regarding hail?
The IEC hail test ensures that a module withstands realistic standard hail. The specification includes:
25 mm hailstone
approx. 7.5 g mass
23 m/s impact velocity
11 defined impact points
5. Can a module achieve HW5 but still fail the IEC test?
Yes. A module may achieve a high HW class but still fail IEC 61215. Without IEC certification, it is not marketable. This is why IEC is the decisive standard for hail safety.
6. What determines the hail class of a solar module?
Mainly the glass thickness and module construction. If the construction remains the same, the hail class typically remains constant. Examples:
2.0 + 2.0 mm glass-glass → HW3
3.2 mm glass-foil → HW4
3.2 + 3.2 mm glass-glass → HW5
7. Which module constructions dominate the DACH market in 2025?
There is a strong trend toward 2.0 + 2.0 mm glass-glass, expected to reach ~80% in 2026.
Current distribution:
65% glass-glass 2.0 + 2.0 mm
13% glass-foil 3.2 mm
12% glass-glass 1.6 + 1.6 mm
4% glass-glass 3.2 + 3.2 mm
1% glass-foil 4.0 mm
8. Which hail class is typically achieved by which construction?
1.6 + 1.6 mm glass-glass: IEC 61215
3.2 mm glass-foil: IEC 61215 / HW4
2.0 + 2.0 mm glass-glass: IEC 61215 / HW3
3.2 + 3.2 mm glass-glass: IEC 61215 / HW5
4.0 mm glass-foil: IEC 61215 / HW5
9. What does HW5 mean in practice?
HW5 corresponds to very large hailstones with high mass and is mainly relevant for special risk regions or specific high-demand construction projects. For standard rooftops in the DACH region, the IEC standard is the relevant and sufficient requirement.
10. Why does SOLYCO focus on 2.0 + 2.0 mm glass-glass and 3.2 mm glass-foil?
Because these two constructions cover 90% of all DACH projects with optimal performance:
Maximum hail resistance
Low weight
High cost efficiency
Robust mechanical design
Real safety comes from construction and glass thickness – not from marketing claims.
11. Does SOLYCO also produce HW5 modules?
Yes, but project-specific. HW5 is useful for special applications, but for most installations it is technically unnecessary and often not economically sensible.
12. What is the role of the VKF Hail Register?
The VKF Hail Register is a recognized reference in the construction industry. It lists building components tested in accredited laboratories. It can be relevant for insurers or special construction projects requiring enhanced hail resistance.
13. Are manufacturer claims about extreme hail resistance always reliable?
Not always. Some manufacturers advertise high HW classes without accredited test reports. Only certified laboratory testing provides reliable, verifiable results.
14. What do planners and installers need for insurability?
HW classes are a nice-to-have, but no substitute for IEC certification.Typically required:
IEC 61215 certificate (SOLYCO publishes all certificates online)
VKF hail classification for specific high-risk regions if needed
15. Which SOLYCO modules are recommended for projects in the DACH region?
SOLYCO recommends the following constructions for the best balance of protection, weight and cost:
SOLYCO glass-glass 2.0 + 2.0 mm
SOLYCO glass-foil 3.2 mm
