New Hail Resiliency Curve Test Redefines How Solar Panels Are Evaluated for Extreme Weather

As extreme weather events increase worldwide, solar testing organizations are stepping up efforts to understand how solar modules withstand some of nature’s harshest conditions. Today, VDE Americas and RETC, both part of the VDE Group, announced the launch of the Hail Resiliency Curve (HRC) test, a groundbreaking protocol designed to pinpoint a solar panel’s true “breaking point.”

Unlike traditional hail tests — which are often limited, outdated, or unrealistic — the new HRC approach simulates real-world hailstorms by firing hailstones of various sizes and speeds at multiple points across the module surface. Panels are subjected to repeated impacts, from small ice pellets at low velocity to large hailstones traveling at high speeds, until glass fracture occurs. The result is a precise chart of how much impact energy a specific panel design can handle before failure.

According to Brian Grenko, President and CEO of VDE Americas, the current hail-risk models widely relied upon by insurers “are severely antiquated and outdated.” The new HRC methodology, he says, offers a more accurate, data-driven understanding of module durability — reducing uncertainty for investors, project developers, insurers and asset owners.

What Makes the HRC Test Different?

The HRC protocol was developed with input from experts across the glass, materials engineering, and photovoltaic industries. It uses statistically meaningful sample sizes and measures failure rates along a full spectrum of impact conditions. This enables scientists to create detailed Weibull distribution curves — graphical representations that can compare a panel’s probability of failure under different hail-impact energies with exceptionally low uncertainty.

Materials engineer Mike Pilliod, who supported the test development, emphasized the importance of breaking enough glass samples to achieve statistically reliable conclusions. “If you’re not testing a representative number of samples to failure, you’re not doing your job as a reliability engineer,” he said.

Why This Matters for the Solar Industry

The introduction of the Hail Resiliency Curve test stands to benefit multiple sectors of the solar value chain:

Manufacturers can now optimize module designs specifically for hail-prone regions, validate glass suppliers, and highlight performance advantages with empirical data.

Project developers gain the ability to assess cost-benefit tradeoffs related to module selection and tracker stow angles, reducing the risk of catastrophic hail damage.

Insurers and financiers can base coverage decisions and premiums on real impact-resilience data, rather than outdated assumptions — helping stabilize project economics in volatile climates.

Flat-mounted solar innovators, such as Erthos, are already using the HRC test to validate their unconventional installation methods, ensuring clients and financial partners have complete confidence in system resilience.

As Cherif Kedir, President and CEO of RETC, noted, “The HRC test fills this knowledge gap by providing actionable data across the complete impact energy spectrum of real-world hailstorms.”

A Step Toward More Resilient Solar Infrastructure

Early adopters of the program include major module manufacturers, tracker companies, and next-generation technology startups. As solar deployment expands into regions with intense weather patterns — from the U.S. Midwest to Australia — the need for rigorous, physics-based hail-resilience evaluation has never been greater.

The HRC test represents a significant leap forward in understanding and improving how solar panels perform in extreme environmental conditions. As the industry continues to scale, innovations like this will play a central role in ensuring long-term reliability, investor confidence, and the protection of solar assets worldwide.