A new hail test for solar panels shoots small to large hailstones at solar panels while aimed to more accurately determine the panel’s breaking point.
Introduced by VDE Americas, the “Hail Resiliency Curve Test” simulates real-world hailstorm conditions where solar panels face numerous impacts from a range of hailstone sizes and wind speeds during severe hailstorms. The test involves firing a series of small to large hailstones at solar panels at various speeds until the glass fractures. The tests’ panels were designed to represent specific models and brands, giving developers and companies accurate data for a panel’s breaking point.
“Conventional hail risk models that are relied upon by many in the insurance community are severely antiquated and outdated,” said Brian Grenko, president and CEO of VDE Americas.
According to VDE Americas, the new test protocol enables:
- Solar panel manufacturers to optimize hail-hardened product designs and demonstrate their performance advantages relative to conventional products;
- Project developers to perform cost-benefit analyses of different solar panels and tracker tilt angle combinations to mitigate hail damage risk; and
- Insurance providers to appropriately size hail damage coverage and premiums based on empirical data rather than speculation.
President and CEO of the VDE’s Renewable Energy Test Center Cherif Kedir said the solar industry has long needed a more rigorous approach to hail testing.
“The Hail Resiliency Curve Test fills this knowledge gap by providing our customers with actionable data on solar panel hail resilience across the complete impact energy spectrum of real-world hailstorms,” Kedir said. “Moreover, the rigorous sample size ensures a more thoroughly vetted solar panel characterization.”
The use case for glass doesn’t really matter, said Mike Pilliod, president and chief technical officer at Central Tension, a glass specialist that was involved in the test’s development. “Automotive glass, cellphone displays, architectural glass, you name it. If you’re not breaking glass — and not testing a representative number of samples to failure—you’re not doing your job as a reliability engineer,” he said.
“What really interests me as a glass reliability engineer are measurement systems that provide a statistically representative probability of failure,” Pilliod said.
The Hail Resiliency Curve test data provides solar stakeholders with unprecedented visibility into solar panel performance under real-world hailstorm conditions, Pilliod said.
Standard panels fail rapidly between 40 J and 80 J, while hail-hardened panels maintain low failure rates until 120 J or more, according to VDE.
“If you gradually increase kinetic impact energy and test a meaningful number of samples to failure, you can generate Weibull distribution curves that plot the probability of glass failure on a product- or bill-of-materials-specific basis with low uncertainty,” he said. “Now you can stack these Weibull curves and compare them. Do the curves overlap? If not, you can be reasonably certain that there is a statistical difference in resiliency.”
Hail risk continues to be the top issue faced by solar projects, according to a recent annual report from risk assurance firm kWh Analytics. While hail accounts for just 2% of insurance claims in the utility-scale solar industry, it makes up more than 50% of total claim costs, with the average hail-related claim reaching $58 million, according to VDE.
Even in regions that are not typically considered hail prone, hail risk should still be evaluated, the report said. North Carolina, not typically considered a high-risk region for hail, represented 19% of total losses incurred.
Research from Central Michigan University found that almost all (99.3%) of solar plants in the U.S. have at least a 10% chance of having hail of 2 inches near the project each year. Over a 25-year span, 100% of large-scale projects have a risk of 2-inch hail, the researchers said.
(Also read: Actionable insights to safeguard solar projects from hail damage & Addressing hail damage risks in utility-scale solar)
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