If you follow professional football, you’re probably aware of the recent Chicago Bears and Arizona Cardinals games when officials had to stop play for the first time ever so the crew could close the stadium’s roof. The reason? An unexpected out-of-season hailstorm in Phoenix, Arizona. The second out-of-season hailstorm to hit the state in less than a month.

Hailstorm season lasts from March to June, and the first half of the year experienced more than twice as many hailstorms as all of 2023. However, many areas across the country sometimes face a secondary peak in hail activity during the autumn months, and 2024 has been no exception to this second hail season.

Intensifying climate change increases the probability of out-of-season weather events, raising the risk levels solar project developers, EPCs, and financiers must consider.

Solar projects must meet design standards for the weather conditions they expect to encounter, or hailstorms will discourage further solar sector investments. New projects can mitigate hail risks with design choices like using fast-stow trackers or hail-resistant modules with 3.2mm tempered glass and backsheet.

Hailstorms Tear Across Central U.S. Reigniting Concerns for Solar PV Systems

In October and November 2024, severe hailstorms swept across the central United States, from the Great Lakes down to Texas, causing significant damage to solar energy installations and reigniting concerns about the vulnerability of photovoltaic (PV) systems to extreme weather events and highlighting the growing risks of hail damage to utility-scale, commercial and industrial (C&I), and commercial PV systems. Hail ranging between 1 inch to 1.25 inches dropped on parts of Texas, while areas of Oklahoma experienced 70 mph wind gusts and quarter-sized hail.  

For example, despite a relatively tame hurricane season in 2023, the country experienced a record-breaking 28 $1 billion-plus weather events, with severe weather and hail events accounting for 17 of those. DNV, an independent expert in assurance and risk management company, estimates that since 2018, hail-related losses on PV facilities in Texas alone have surpassed $600 million.

The result? A corresponding surge in insurance premiums, with some premiums rising by a staggering 400%, limited to only $1 million or 15% of physical damage deductible and capped between $15 million and $40 million for hail-damage coverages, regardless of project size. These insurance changes mean that for utility-scale solar projects with CAPEX higher than $100 million, the insured value only covers a tiny portion of the potential loss, and many events may exceed those conditions leading to force majeure.

Mitigation Strategies: Solar Tracker Stowing and Advanced Forecast Modeling

Solar tracker stowing techniques offer one of the most effective strategies to mitigate hail damage to PV systems. System operators can program solar trackers to adjust PV module angles during hail events — a stow angle — to significantly reduce the damage risks.

Recent research has led to the development of hail stow strategies that position solar modules at the maximum angle the tracker allows, away from prevailing winds, to minimize direct hail and associated wind impacts. For example, an automated hail stow solution that uses advanced algorithms and sophisticated software combined with meteorological data to automatically adjust the positioning of solar panels during hail events.

Advanced forecast modeling is crucial for effective stowing strategies. Multi-radar approaches provide real-time, highly accurate meteorological data updates, allowing for automated and timely mitigation against hail events and customizable stow thresholds based on hail size, probability, and radius.

Hail-and-Wind-Resistant PV Modules Are a Must

While stowing strategies are crucial, PV modules’ inherent durability plays a significant role in ensuring resilience against hail damage, and the introduction of 3.2mm tempered glass and high-quality backsheets include two critical features for greater protection.

3.2mm Tempered Glass

PV modules with 3.2mm heat-tempered front glass demonstrate remarkably more hail resilience than those with thinner 2mm glass. The thicker glass provides better impact resistance, and the complete tempering process enhances its mechanical characteristics. This increased durability is vital for withstanding the impact of giant hailstones, which can cause catastrophic damage to solar panels.

High-Quality Backsheets

While the front glass is the first line of defense against hail, the backsheet enhances overall PV module durability and performance. High-quality backsheets provide essential functions and benefits, including:

1. Protection against moisture, dust, and impurities

2. Electrical insulation to prevent short circuits

3. Mechanical stability to enhance overall panel strength

4. Weather and UV resistance for long-term durability

The combination of 3.2mm tempered glass and a high-quality backsheet creates a more robust PV module better equipped to withstand severe weather events, including hailstorms.

EPCs and developers must address hail challenges head-on to continue growing and providing clean, renewable energy while mitigating the risks from out-of-season extreme weather events. 

Interested in avoiding hail damage and deploying more resilient and sustainable solar PV systems? Follow the link to learn more.