The Standard Every Certified Panel Is Tested Against
UL, Underwriters Laboratories, certifies PV modules for mechanical durability, including hail impact, under two standards: UL 1703, the original US PV module safety standard established in 1986, and UL 61730, a harmonized US and IEC standard created in December 2017. UL’s hail testing fires ice balls from a pneumatic cannon at 10 to 13 critical locations on a module, with the standard test using 25 millimeter, roughly one inch, ice balls traveling at approximately 52 miles per hour. A separate historical impact test drops a 2-inch steel sphere from 51 inches onto the panel surface, simulating a hailstone of about 1 and three-eighths inches at terminal velocity.
This is the baseline every certified panel on the market has already passed before it is ever installed. The real-world question a homeowner or rep is asking, what happens in a specific storm, sits on top of that baseline rather than replacing it.
What a Wind Rating Signals for a Coastal Install
Panels installed in coastal or hurricane-exposure areas are commonly recommended to carry a wind-speed rating of at least 160 miles per hour, with some premium panel lines certified to 180 miles per hour or higher. That is a direct, checkable specification, not a marketing claim, and it is worth confirming against a specific panel manufacturer’s own datasheet rather than assuming every certified panel carries the same rating, since this recommendation reflects general industry guidance rather than one single named standard.
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Book a Solar CallWhy Glass Thickness Is the Spec That Separates Panels
Panel glass thickness materially changes hail survivability. In one comparative ice-ball test built on UL-linked hail testing data, 97% of panels with 2 millimeter glass failed a 45 millimeter ice-ball impact test, while only 13% of panels with 3.2 millimeter glass failed the identical test. “Hail resistant” is not a uniform property across all panels carrying UL certification, and glass thickness is the concrete, checkable spec that explains most of the difference.
The 97% and 13% figures above come from an aggregated comparative test rather than a single named UL report this guide could independently re-verify with a working link. Treat the numbers as directional evidence that glass thickness matters a great deal, not as a guaranteed pass or fail rate for any specific panel model.
The States Where a Durability Spec Stops Being Abstract
Wind and hail ratings are not an abstract spec sheet detail in every market equally. More than 75% of one major dealer network’s pre-acquisition sales volume came from California, Florida, and Texas combined, exactly the states where hurricane and severe-hail exposure is highest. In markets with that much concentration, confirming a panel’s certified wind rating and hail-testing pedigree before a homeowner signs is not a theoretical exercise, it is the spec that determines what happens the first time a real storm rolls through.
Sources
The external data in this article draws on the sources below. Figures described in the text as estimates or industry triangulations are directional and are not attributed to a single dataset.
- UL Solutions, manufacturers say hail yes to solar panel testing
- SolarQuarter, SunPower acquires Sunder Energy dealer-network coverage