Four Solar Industry Weather Wants for Hail Risk Management

A recent Woods MacKenzie webinar on managing hail risks for the solar industry highlighted the growing need for weather risk mitigation solutions. DTN Solution Engineer and Meteorologist Matt Gaffner joined Woods MacKenzie Research Director for Wind and Solar O&M Leila Garcia da Fonseca and Array Technologies Senior Product Manager Sanket Shah on the webinar to discuss how weather intelligence can help mitigate hail risk.

Hurricanes, blizzards, tornadoes, hailstorms, and wildfires are all weather events that pose risks to solar farms, but the costliest weather event that threatens the solar industry is not the most frequent or deadly. Hailstorms have been the industry’s biggest risk for asset damage and loss. For example, Solar Power World reported that summer hail in Texas in 2022 caused over $300 million in damage to solar fields — a figure 10 times more costly than solar damage caused by Hurricane Hanna in 2020. This has prompted solar owners and developers to model weather risks through a new lens.

Hailstorms have been the biggest weather risk to the solar industry for asset damage and loss.

During the webinar, Gaffner noted that DTN has been accumulating hail data daily for more than 20 years. The data was primarily used after a hailstorm to verify damage to a structure or support a claim for insurance companies. Now, the conversation has pivoted to before the storm for risk mitigation.

“Tracker manufacturers, solar owners and operators, and insurance companies are all asking for the same type of hail forecasts to manage hail risk,” Gaffner said. “It substantiates and shows the value of all sectors of the industry working together to address the challenge.”

The hail forecasts are a part of the larger DTN Storm Corridor solution. The cloud-based API uses a multi-radar approach to track the speed and direction of individual storm cells with the probability of hail and the maximum estimated hail size. The platform also integrates National Weather Service information with DTN ArcGIS for easy tracking of storms related to solar assets. Customers can integrate the solution into their business systems or hardwire it to automate panel pivot decisions.

Gaffner shared with webinar participants that in his decade working with solar stakeholders, four main themes have emerged around weather intelligence.

1. Solar operators want short-term forecasts

Both public and private weather companies provide convective outlooks, which show the predicted severity and general area where storms are possible; several offer a daily hail probabilistic forecast.

“It is a great tap on the shoulder to let an operator know that hailstorms are possible today,” Gaffner said, “but the polygons cover multiple states, and at the end of the day, not everywhere in that polygon will be hit by hail — some won’t even have rain.”

Solar operators want a hail forecast for site-specific locations 30-60 minutes before impact so they can pivot the panels to minimize damage without sacrificing energy generation. Called hail stow, tracker-mounted solar panels are moved into a position with a high degree of tilt, reducing the impact energy of hailstones. Most solar companies report a 30-minute notification is sufficient in most cases.

Solar operators want a hail forecast for site-specific locations 30-60 minutes before impact so they can pivot the panels to minimize damage without sacrificing energy generation.

DTN Storm Corridors displays real-time radar image of a hailstorm approaching a solar farm. The red, white, and orange “fan” shapes denote the speed and direction of the storm.

2. Weather information must be actionable

Solar owners and operators want detailed storm information with hail alerts, such as storm speed, direction, and the probability of hail and its size. The additional information helps with decision-making or automating a decision based on the additional information.

Some solar companies pair the solar track technology with real-time weather insights and proactive alerts to automate hail stow. For example, using the DTN Storm Corridor API, a solar operator can set thresholds based on hail size or probability for individual sites or all sites to automate the risk mitigation process.

3. False alarms are okay

Ground-mounted solar modules with single-axis trackers move the panels with the sun’s trajectory. Placing solar panels in hail stow in the late evening or during cloud cover from nearby storms is a low risk due to already reduced power generation. But most hailstorms pop up on sunny days when solar panels are angled to maximize capture. Hail alerts during this time force solar operators to balance generating energy with reducing hail risk.

Gaffner said that most solar companies err on the side of caution and choose hail stow over leaving the panels exposed, even if the alert may be a false alarm.

According to a kWh Analytics Solar Risk Assessment report, the false alarm/hail stow approach is beneficial in the long run. In one study, the insurance provider found that, assuming a $22/MWh PPA, moving into hail stow during extreme weather events throughout the year resulted in a production loss of $12,000 or 0.1% of the asset’s $9.75 million estimated annual revenue. But the hail stow program resulted in a property insurance premium reduction of $2 million per year.

Moving into hail stow during extreme weather events resulted in a production loss of $12,000 or 0.1% of the asset’s $9.75 million estimated annual revenue. But the hail stow program resulted in a property insurance premium reduction of $2 million per year.

4. There can be no misses

While solar investors and owners tolerate false alarms, that’s not the case with false negatives or misses. A single storm event can cause extensive damage to a solar field. One 2019 hail event in Texas caused up to $80 million in losses to solar modules — and was significant enough to change how investors, insurance companies, and other stakeholders evaluate hail risk.

DTN Storm Corridor uses a multi-radar approach and a cloud-based API to ensure reliable, consistent weather intelligence.

The future of hail risk mitigation

One of the prevailing webinar questions related to increased hail risk; Gaffner said factors other than climate change were shown to be more likely to increase risk, such as a company’s mitigation strategy.  “There is a spirit of collaboration to reduce hail risk, not only between investors and insurance companies but also among competitive solar companies,” Gaffner noted after the webinar.  “The public forum and commitment to reduce hail risk furthers the continued growth of solar fields and solar generation. DTN weather intelligence, in collaboration with our solar partners and customers, supports this new approach to weather risk management.” Array Technologies sponsored the webinar, “Managing hailstorm damage risk at your utility-scale solar installations.” You can replay it on demand.

Learn more about DTN Storm Corridor visit here.