By Claire Kearns-McCoy & Paul Wormser

This article was originally published in pv magazine - November 2024 Edition.

Claire Kearns-McCoy and Paul Wormser consider the lasting impact of a May 2019 hailstorm that damaged 400,000 solar panels in Texas. 

A freak hailstorm that hit West Texas on May 17, 2019, prompted an insurance payout totaling tens of millions of dollars, sobered the industry, and rallied critics of solar.

Further high-profile damages have led to solar project insurance premiums rising by as much as 400%. At the same time, PV project coverage has reduced. Deductible requirements have risen to $1 million, or 15% of physical damage. Hail damage insurance regularly stops at between $15 million and $40 million, regardless of project size.

GCube Insurance has estimated that hail accounts for more than half of solar-related insurance payouts in value terms, despite representing less than 2% of claims.  

With projects cropping up in hail-prone regions and featuring panels with thinner wafers, frames, and larger cells and modules, the industry needs mitigation strategies and improved post-storm testing to assess damage and its causes.  

Mitigating hail damage begins with site selection, vulnerability assessment, and equipment selection. Several solar tracker companies offer a “hail stow” feature providing speedy, near-vertical stowing of panels by tilting them as much as 75 degrees.

Even so, the risk persists. In March 2024, another spring storm battered an East Texas PV project with golf ball-sized hailstones. Thousands of panels were damaged and entire sections were riddled with cracked glass.

Risk mitigation

Larger, thinner, dual-glass panels are more vulnerable to hail. Some suppliers are raising hail impact testing requirements, but there is still a long way to go. As the battle between solar panels and the weather continues, the industry must adapt. Damage assessment methods, including electroluminescence (EL) testing, infrared scanning, and visual inspection, have evolved. To mitigate risk, careful selection of project locations, as well as tracker and panel design, is essential.

Wind and hail protection must be balanced, with worst-case scenarios envisaging vertical hail and horizontal winds. Balancing both requires the right stow position and trackers.

Adjusting panel tilt to 50 degrees to 75 degrees can help. A 60-degree tilt raises panel hail-survival panel rates by 82% to 99%.

Advanced weather prediction systems provide early warning of storms to aid stowing, especially for fast-stowing single- axis trackers.

If insurers are unnerved by project location, maybe it’s time to change site. Understanding insurance coverage and rigorous panel durability testing are essential to safeguard PV projects. 

Cell cracks

Post-storm visual inspection can spot cracked glass, but may not pinpoint cell cracking. Tracking weather-adjusted project output is a routine option on many utility-scale sites and a sudden dip can indicate damage.

Some hail damage may take time to manifest in reduced output, however. Infrared scanning, which detects the temperature gradients indicative of “hotspots,” helps to highlight immediate issues. Although quicker and more affordable than EL testing, it is also less comprehensive in assessing underlying damage.

EL testing serves as the preferred method for the detection of microcracks within the silicon cells of a solar module. This type of testing effectively identifies early-stage cracks that are not visible to the naked eye and might not immediately affect performance, but could cause problems in the future. Such issues can affect solar cell performance and may even lead to potential failure.

Testing and insurance

To enhance project preparedness in case of a hailstorm, site owners should establish comprehensive supply agreements that include provision for special module testing as part of their certification and/ or reliability testing protocol. This may also involve specifying the need for batch testing, whereby a sample of production output is tested, including hail resistance testing. Given the variability in glass quality and manufacturing processes, periodic batch testing helps ensure that module performance and resistance to damage from hail is consistent across a full production run.

It is also important to obtain a baseline of EL images at both the factory and post-installation stages. Comparing these images before and after storms helps identify new damage and supports the insurance claim process. Insurance considerations are closely tied to this process.

EL testing provides critical evidence of module condition but understanding and documenting module condition thoroughly is also necessary, to prevent disputes and support claims, especially since some policies require a higher threshold of damage before coverage applies.

It is also important to maintain comprehensive records of module testing, including a detailed bill of materials and historical data, as this documentation supports insurance claims and helps track module performance over time.

The preparation for hailstorm mitigation can start even before modules have been chosen. As part of the equipment selection process, buyers can consult their insurance provider to see if their project and choice of equipment will have an impact on their premium or coverage. Site owners should be sure to share all the measures they are taking to reduce risk.

Severe weather risks and insurance hurdles can be managed with thorough preparation and smart equipment selection. As more solar projects are built in hail-prone locations, overcoming such obstacles remains a priority. Using reliable resources and advanced technology, the industry can address the challenges posed by hail damage and ensure that solar projects stand resilient against the storm.

Claire Kearns-McCoy is Senior Engineering Manager at CEA. She has extensive experience with module field inspections and analysis of EL imaging tests.

Paul Wormser is Vice President for Technology at CEA, where he is responsible for supply chain management and the technology and quality team.