SOLAR VS HAIL: PIVOTING AWAY FROM DANGER
The Threat of Severe Convective Storms
Severe storms with the potential for large and damaging hailstones are formed through a convective process as heat and moisture move vertically from strong updrafts in the atmosphere. Within the tall cumulonimbus clouds that form, raindrops can start to freeze higher in the atmosphere, growing into larger and larger hailstones until the updrafts can no longer support their weight and they fall to the ground.
Most hailstorms are made up of a mix of different sized hail. However, even a small percentage of damaging hailstones (we define as at least one inch/25mm), with their increased mass and higher terminal velocities, result in impacts with exponentially greater kinetic energy—often enough to substantially damage equipment and shatter glass.
Representation of the diameter of hailstones which have been documented within solar PV hail claims reported to AXIS.
Geographically, hail-producing cumulonimbus clouds are more likely to form and provide a larger volume of hailstones in areas that encourage these conditions, such as in areas adjacent to mountain ranges and continental interior plains like “hail alley” in Texas, and much of the US Midwest.
These open, sparsely populated spaces are often identified as ideal locations for solar farms. However, as developers have built increasingly vast projects in these areas, the true scale of the risk posed by hailstorms—often previously underreported in weather records—is now becoming clear. Now, acres of glass are effectively acting as hail datapoints, highlighting the devastating impacts for asset owners and stakeholders.
Climate instability and a changing atmosphere are increasing temperatures and humidity in parts of the world, fueling stronger storms and altering where damaging hailstorms form. Climate model studies project hailstone size to rise globally, hailstorm severity to increase in most regions, and storm frequency to upturn in Australia and Europe in particular [1].
One global estimate of one inch (25mm) hail probability indicates that hail exposure spreads far beyond North America, traditionally considered one of the greatest risk areas.
The global estimated average annual probability of hail with a diameter >25mm, normalized to areas of 100km×100km, for 1979–2015[2]
Regional Deep Dive
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[1] Raupach, T.H., Martius, O., Allen, J.T. et al. The effects of climate change on hailstorms. Nat Rev Earth Environ 2, 213–226 (2021). https://doi.org/10.1038/s43017-020-00133-9
[2] Andreas F. Prein, Greg J. Holland, Global estimates of damaging hail hazard, Weather and Climate Extremes, Volume 22, 2018, Pages 10-23, ISSN 2212-0947, https://doi.org/10.1016/j.wace.2018.10.004. CC BY 4.
