Hail damage to solar projects: 1% of filed claims, but over 50% of total losses

From the magazine

A study by underwriter GCube Insurance found that while hail damage accounted for just 1.4% of insurance claims filed for US solar projects in the five years preceding the study, those claims made up 54% of total solar losses.

Data from insurer Axis shows that throughout the world, its open and closed claims for hail damage between 2019 and 2025 affected 1.3 million solar modules and 2.7 GW of capacity. And these add up to a total gross claim amount of $342 million.

Hail damage is a big problem for the PV industry, particularly in the United States, where Axis says the vast majority of these claims originate. Texas and the Midwest region are particularly high risk.

“As an industry, we didn’t anticipate this problem. Solar first grew in places like California and New Jersey, where there’s not a lot of severe hail. The problem has been getting worse, mostly because solar has grown so much in the US and we’re seeing many more projects in regions that are prone to hail,” said Jon Previtali, vice president of digital services at solar technical advisory firm VDE Americas.

Aside from the location, technology trends have contributed to the problem. Modules used in large-scale projects have increased in size as manufacturers chase economies of scale in shipping and materials, and this leaves a larger surface for hail to fall on, and a higher chance of an individual module being hit and damaged.

Manufacturers have also started to use glass panels on both sides of modules, rather than front glass and a polymer backsheet. This requires use of thinner glass, which is usually “heat strengthened” rather than fully tempered. Previtali estimates that 3.2 mm fully tempered glass is roughly twice as resistant to hail impacts as the 2 mm heat-strengthened glass now used in many panels. Processes exist to fully temper glass as thin as 2 mm, which would likely make it more resistant to damage from hail, but issues of cost and technology transfer have so far kept this from mainstream use in the solar industry.

Faced with the damage caused by hail in recent years, companies from across the US solar supply chain are collaborating to develop solutions and ensure they are adopted as widely as possible. For modules installed on fixed racking systems or rooftops, stronger glass might be the most practical solution. But since a large portion of ground-mounted solar in the United States is built on trackers, there’s another option.

Hail stowing

Hail stowing, where the tracker shifts the modules to a high angle to deflect hail impacts and reduce the area of glass being hit, has proven to reduce damage to PV modules. “Where we’ve seen hail damage, the most common factor is the lack of reliable hail monitoring and a stow function. Even the least resistant modules, if you put them in hail stow position, you can avoid a significant amount of damage,” said Previtali.

Tracker maker Nextracker offers its Hail Pro solution to customers, which includes hardware allowing for rapid stowing at an angle of up to 75 degrees on either side, and software that can connect with third-party weather forecasting services to stow automatically when hail is predicted, or other conditions are met. It also allows operators to initiate stowing in either direction with a single click.

Earlier trackers typically stowed for hail at a 60-degree angle. Alex Roedel, VP design and engineering at Nextracker explained that the additional degrees of rotation come as the result of increasing research and collaboration among independent engineering firms, testing laboratories, project developers, and others along the solar project value chain.

“75 degrees wasn’t a number picked from the sky. We did rigorous lab testing and hail damage risk analysis to be able to say this is the correct angle that we believe balances our tracker system as well as risk mitigation for the module,” said Roedel.

Module manufacturers, according to Roedel, are particularly happy to collaborate on hail protection, and see work being done on the tracker side as helping open up more design and material options for them. He sees some market correction, with manufacturers opting for stronger frames and slightly thicker glass, and some specifically marketing modules as hail resistant, but module prices are still low, and manufacturers have very strong cost constraints. “It becomes this combination of technologies. You could overcorrect and go to 4 mm to 5 mm glass. Or you could combine it with a smart system that goes at a high angle. Because module manufacturers don’t want to replace a race to the bottom with a race to the top, where their product costs go through the roof.”

Triple threat

For some trackers, high-angle stowing for hail can conflict with strategies for other extreme weather, such as strong wind or flooding, where a horizontal or wind-facing position might be preferable. But not where those conditions are accompanied by large-diameter hail.

Here, trackers can use more robust designs and increased wind damping to allow the structure to withstand stronger winds, leaving the stow position open for hail protection. “We’re designing for all of these different simultaneous scenarios. We would never put out a situation where you’re relying on conflicting controls and software functionality of it. We want a system designed for both scenarios of winds changing direction and hail or some of these other events occurring,” said Roedel.

Andrew Griffiths, VP asset management at Nextracker, added that the company’s Horizon Hail Pro trackers include “360 degree” wind protection, meaning the tracker is designed and warrantied to safely stow in any direction, facing into or away from the wind.

Experts say that the industry is increasingly taking note of the risk posed by hail and other extreme weather events, and implementing mitigation measures into projects from the start, even where this means extra cost. “There are some extra costs, in the hardware and in subscribing to reliable weather forecasts, but the juice is worth the squeeze when you consider the damage that can happen otherwise. Every smart system owner or operator is doing this now,” said Roedel.

Previtali agreed that the industry is increasingly taking notice of extreme weather risk. “Often, the project planners are very hopeful that they aren’t going to get any hail at their site, and they don’t want to spend the extra money to set up hail monitoring and stow functionality. But the tide is turning on that, and I would say at least 50% of projects being developed now know they have to take hail, wind, etc., into consideration,” he said.

Previtali added that he sees many existing projects looking to retrofit hail mitigation. In most cases, where trackers are already in use, this can be done by adopting new software without the need for any physical retrofit. Occasionally, projects built to stow horizontally in strong wind conditions may require the addition of more structural elements and dampers, which are typically available from tracker manufacturers.

Insurance trends

Insurance providers have also played a key role in the increased collaboration on hail between industry players, and are showing willingness to factor hail risk and mitigation measures into their cost models. “The risk is never zero, but what we’re seeing is that an effective hail stow protocol can reduce hail losses for typical utility scale projects from at least $50 million down to below $5 million,” said Previtali.

He pointed out that VDE has seen situations where one project suffered severe hail damage, while others hit by the same storm escaped relatively unscathed – proving the effectiveness of stowing. VDE has worked with insurance provider kWh Analytics to ensure it can get the right information on a project’s defense strategies for hail, and offer lower-cost insurance where proven mitigation has been well implemented. “That’s a very novel concept that we’re hoping other insurance providers will adopt as well,” he said.

Nextracker’s Griffiths agreed, noting that a few years ago, if one project was hit by hail, nearby projects often saw higher insurance premiums. But that is increasingly no longer the case. “Insurers are getting more savvy, as a result of this collaboration between equipment manufacturers, module manufacturers, developers, and weather forecasters. They’re able to dial in those risk factors locally to what the actual project will see,” he explained.

Roedel also sees the collaboration and rapid progress made on reducing hail damage as evidence of the solar industry’s overall resilience.

“It’s a completely different world than it was a few years ago where everyone is just terrified of hail. We’re starting to prove now that with the right technologies we can solve for any risk. And that’s a brilliant thing,” he concluded.

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