Latest Solar Risk Assessment Underscores Importance of Hail-Resistant PV Modules

The 2025 hail season is well underway across large swaths of the country. In June, two “Particularly Dangerous Situation” (PDS) Severe Thunderstorm Watches were issued across Texas, Oklahoma, and Kansas — an extremely rare occurrence, with the National Weather Service (NWS) issuing a PDS only 25 times since 2006. The extreme storms packed hurricane-force wind gusts and dropped a bevy of large hail across the region. Although grapefruit-sized hailstones were reported, most of the hailstones that fell were around 2 to 2.5 inches, about the size of a tennis ball.

The financial reality of these storms for solar projects is stark, with hail damage representing the single most devastating weather-related threat to utility-scale solar installations across the United States. Despite accounting for only a small fraction of total weather incidents, hailstorms are responsible for an overwhelmingly disproportionate share of financial losses, making this risk a critical concern for engineering, procurement, and construction (EPC) companies and developers operating in hail-prone regions.

Below, we examine the latest numbers on hail damage to solar projects and how utility-scale solar EPCs and developers can mitigate these risks by using PV modules with tempered 3.2mm glass and backsheets.

Financial Impacts of Hail on Solar Projects

According to the recently released 2025 Solar Risk Assessment from climate insurance provider kWh Analytics, hail accounts for a staggering 73% of all weather-related financial losses for U.S. solar photovoltaic projects, despite representing just 6% of the total number of loss incidents. This extraordinary disparity underscores the catastrophic financial impact that single hail events can have on utility-scale installations.

The average cost per hail damage claim has reached approximately $58.4 million per incident, with some individual events resulting in hundreds of millions of dollars in losses. The insurance industry has responded to these escalating risks with premium increases of up to 400% in high-risk regions, making proper risk mitigation strategies essential for project viability.

Keep in mind that more than 99% of the country’s solar plants face a 10% or higher annual probability of experiencing hailstones measuring 2 inches or larger in diameter, according to research from Central Michigan University. The likelihood of a project experiencing a significant hail event risk jumps to 100% over a typical 25-year operational lifespan and sits at 91.18% even over a shorter 10-year timeframe.

In response to escalating hail losses, the insurance market has created additional challenges for project development and financing. Premium increases, coverage limitations, and in some cases, complete refusal to provide coverage in high-risk regions have altered project economics. Insurance carriers require more detailed documentation of risk mitigation measures, equipment specifications, and operational capabilities before providing coverage.

Projects will need to demonstrate comprehensive hail risk management, and PV modules with proven hail and wind resistance.

Evolving Regional Risk Patterns of Hailstorms

Climate change is fundamentally altering both the frequency and severity of hailstorm events across traditional and emerging hail risk zones. Warmer atmospheric temperatures enable greater moisture retention, approximately 7% more for each degree Celsius of warming, which contributes to stronger updrafts and the formation of larger hailstones.

Along with population growth into previously undeveloped areas prone to hail, the expanding geographic distribution of hail risk across the U.S. creates new challenges for utility-scale solar development. Nearly 50% of all existing installed solar capacity falls within regions experiencing intense hail activity, with approximately 158 days of damaging hail occurring annually nationwide. The notorious "Hail Alley" region, stretching from Texas northward through Colorado, Nebraska, and Wyoming, experiences the highest concentration of severe hailstorms.

However, kWh’s 2025 risk assessment data showed surprising updates to traditional assumptions about hail-prone regions, since North Carolina, not typically considered a high-risk area, accounted for 19% of total hail-related losses. The implications of this for solar project development extend beyond simply acknowledging increased risk levels. Traditional hail risk modeling based on historical data may underestimate future exposure, particularly in regions like North Carolina, which is experiencing shifting weather patterns, the Northeast, which is expected to see an increase in hail frequency, and other areas experiencing larger average hailstone sizes.

This evolving risk landscape requires strategic approaches to both equipment selection and operational procedures. Projects designed today must account for potentially more severe conditions over their 25-year operational lifespans, making forward-thinking design choices and robust operational capabilities increasingly important.

The Critical Role of PV Module Hail Durability Testing

The primary risk of damage for solar modules is hailstones breaking the glass, a problem that continues to make headlines as Tier 2 manufacturers struggle with quality control amid pricing pressures. This risk has made the relationship between glass thickness, tempering processes, and hail resistance a critical engineering consideration for project developers.

To address the growing concern of hail risks, Renewable Energy Test Center (RETC) developed “the industry’s first-ever commercial beyond-qualification test for severe hail,” called the Hail Durability Test (HDT). The test results revealed that modules constructed with 3.2mm fully tempered front glass exhibit approximately twice the hail resistance compared to modules using 2/2mm heat-strengthened glass. This difference stems from both the increased thickness and the superior strengthening process used for thicker glass. While 3.2mm solar glass undergoes full tempering, thinner 2.0mm glass receives only heat-strengthening treatment to control manufacturing costs.

Reducing Expected Average Annual Loss with Vertex N

Engineered using the testing specifications to withstand the impact of hailstones, Trinasolar’s Vertex N 620W modules with 3.2mm tempered glass and backsheet showed no defects in tests with hailstone sizes:

• 45mm at a 0-degree tracker stow angle

• 55mm at a 50-degree tracker stow angle

• 65mm at a 60-degree tracker stow angle

Trinasolar’s 2/2mm Vertex modules showed no defects in tests with hailstone sizes:

• 45mm at a 50-degree tracker stow angle

• 55mm at a 65-degree tracker stow angle

The latest Kiwa PVEL Module Reliability Scorecard confirms these findings, with Trinasolar’s glass-backsheet and hail-hardened Vertex modules receiving recognition for their outstanding durability and performance.

The economic benefits of selecting hail-resistant modules include more than just the initial procurement cost differential. Based on VDE America’s modeling assumptions for a 100 MWdc installation and replacement costs of $0.51/W, including modules, installation, removal, and disposal, the selection of Trinasolar’s Vertex N 3.2mm tempered glass modules with a backsheet at a 60-degree stow angle can reduce the expected average annual loss (AAL) by more than $1 million compared to 2.0mm dual-glass alternatives.

This financial advantage becomes even more pronounced when considering the total cost of ownership over a project's 25-year lifespan. The AAL calculation encompasses not only direct module replacement costs but also associated labor expenses, transportation costs for multiple site visits, system downtime, and potential warranty complications.

Interested in learning more about how Trinasolar’s Vertex modules hold up in extreme weather? Download our ebook A Journey with Trina Solar’s Trinasolar’s Vertex PV Modules Across North America’s Extreme Environments and join us on a journey to mitigate weather-related risks for PV projects with improved resilience, better performance, and more solar value.

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