Microgrids Need Solar… and Solar Panels Need to Withstand Storms and Hurricanes

Climate-driven storms are damaging solar panels as solar installations proliferate.

Since 2004, solar has been the energy source growing most quickly globally, with an average growth rate of 25%, according to a new report, Solar Under Storm III, from RMI–formerly Rocky Mountain Institute–that provides recommendations on strengthening the integrity of panels.

This report follows up on the findings of Solar Under Storm (2018) and Solar Under Storm II (2020), Solar Under Storm III updates best practices for designing and installing solar PV in regions susceptible to hurricanes.

The first two reports looked at design and construction choices that allowed some solar systems to survive Category 5 hurricanes like Irma and Maria, while others failed.

Lessons from Hurricane Beryl

Solar Under Storm III describes lessons learned from Hurricane Beryl, which was the earliest Category 5 hurricane ever recorded in the Atlantic.  It ravaged parts of the Grenadines in the eastern Caribbean in July 2024.

“People aren’t used to building to Category 4 or 5 hurricane resilience standards,” said Christopher Burgess, director of projects,  RMI Islands Energy Program.

Between 1979 and 2017, the number of major hurricanes increased, and the National Oceanic and Atmospheric Administration predicts there will be an increase in Category 4 and 5 hurricanes, along with higher wind speeds.

Why solar in microgrids needs to be resilient

“This is especially important for microgrids, which are often critical power for clinics, hospitals, telecommunications, police and fire. “Without solar intact, a microgrid will be without its primary source of generation,” he said.

To gather information about solar panel damage from storms, RMI sent a team of structural engineers to the Grenadines to check on how panels weathered Hurricane Beryl’s 170-mph to 180-mph winds.

The team identified numerous challenges. First, solar panels in general have become larger, which means they’re more vulnerable to damage during intense storms, Burgess said.

The industry has moved away from smaller format modules that are generally 250 watts and is now installing 400- to 500-watt panels. Structurally, these modules are much weaker, are usually thinner and have more surface area–especially on the back sheet–that’s exposed to high winds.

Modules are flimsier as manufacturers try to cut costs

The modules are weaker because manufacturers are trying to lower their costs while boosting the output of the panels, Burgess said.

The RMI team looked at how vulnerable panels are to low-cycle fatigue, which can occur when high winds press on the back of panels and let go thousands of times.

“It’s like taking a soda can and bending it back and forth, the aluminium eventually tears off,” Burgess said.

To shore up solar panels, the RMI report calls for manufacturers to submit their panels to testing. Such tests are conducted by UL Solutions, the International Electrical Code Council and other organizations.

Manufacturing panels to meet structural requirements adds 5% to 7% to the cost of a new panel.  Panels can also be retrofitted to meet the criteria, Burgess said.

Installing a washer for about $2 a module

What’s needed is a special washer that replaces the round washer that attaches the module to the rack. The washer is stainless steel and thicker, and costs 50 cents a washer, or about $2 a module, Burgess said.

This issue not only applies to the Caribbean. Solar modules on the East Coast, especially Florida and the Gulf Coast, are also vulnerable to storms and hurricanes, Burgess said.

In addition to adding the washers to new or existing modules, solar buyers should be cautious about manufacturers’ testing claims.

“They aren’t always abiding by quality requirements,” Burgess said.

On the islands RMI visited to check on the status of solar modules after Hurricane Beryl, the team found that installations that didn’t meet Category 3 storm standards were damaged.

“The entire array got ripped apart,” he said.

Recommendations that grew out of the damage from Hurricane Beryl

The RMI report updates technical recommendations based on the team’s visit to the Grenadines.

According to the report, solar installations should focus on proven practices such as dual-post piers, through-bolting, lateral racking support and vibration-resistant connections.

The report also identifies common failure points, including inadequate load design and module frames’ low-cycle fatigue. It focuses on the importance of the industry collaborating to improve resilience standards for solar systems. It calls for shared testing protocols, material certification and information exchange.

Such efforts are especially important, given that solar installations have grown so quickly in recent years.

The work is also critical for microgrids, which are often deployed to provide resilience in regions susceptible to hurricanes.

The importance of microgrids in the Caribbean

In 2020, RMI released a report saying the Caribbean is ripe for microgrid development because of the challenges of hurricanes, but financial constraints are a challenge. The RMI report, “Green Stimulus in the Caribbean,” provided policy and funding suggestions to help boost both distributed energy resources (DER) and microgrid development in the region.

When solar is the primary generation source for microgrids and other installations, it’s critical to ensure the solar modules survive the increasing number of storms, said Burgess.

“The more we rely on solar as primary generation, the more we need to do better to secure these systems. It doesn’t cost much,” he said. “With the right testing and the right bolts, modules are proven to survive.”