Solar Panels May Handle Hail Better Than Some Metal Roofs

Research shows that in many cases, solar panels have shown less damage from high wind and hail than lower quality metal roofing.

Solar panels are installed on exposed roofs. So when people live in areas that have frequent hail storms, wind storms, or hurricanes, it is natural to ask if solar panels will hold up through harsh weather. It is especially relevant now that we are experiencing more extreme weather resulting from climate change.

Solar Panels Versus Hail–From the Field

According to ARE Solar,  “In May of 2017, a particularly intense hail storm tore through the Front Range.  It was so destructive that it knocked the Colorado Mills Mall out of commission for nearly an entire year.

“The National Renewable Energy Lab (NREL) is located just about 2 miles away from the Colorado Mills Mall.  Of the 3,168 solar panels at the lab, only 1 (one!!) was damaged by the same storm.  Additionally, while the production dropped during the storm, once it passed, the panels began to perform like nothing happened.  This is a great testament to the durability of the modern day solar panel.”

Editor’s Comment: Hail resistance in solar panels is not monolithic. Different manufacturers use different testing methods, and new panel types may not stand up to extreme hail as well as previous products. They may include less tempered glass, for example, or thinner sheets.  

I recommend reading this article by Solar Power World. It notes, for example, that many utility-scale projects’ have “dramatically increased use of bifacial modules, to capture both direct and reflected light and increase output. Bifacial’s typical glass-on-glass format features two sheets of thinner glass that are often not fully tempered; instead they are typically heat-strengthened — with about half the strength of fully tempered glass. While the choice to use thin glass reduces weight and material cost compared to typical thicker, fully tempered glass, it potentially makes bifacial modules more vulnerable to severe hail impacts.” In simple terms, tempering is key, and not all panel brands use tempered glass as a standard. Read the find print. JinkoSolar products, for example, include both tempered glass and other durability enhancements.

Metal roofs made of thinner gauge material may actually be more likely to suffer damage from hail than tempered solar panels. Source: Brava Rooftile

Even though solar panels are made of glass, it is thick, durable, tempered glass that holds up well to the impact of hail storms. In fact, solar panels take on hail better than most roofs. The National Renewable Energy Laboratory surveyed tens of thousands of solar system installations and found the probability of panel failure was below 0.05% during adverse weather events such as hail storms. That is because mainstream solar panel manufacturers test their products for their ability to survive impacts from the largest hailstones. 

I witnessed this myself, last summer when we experienced an extreme hailstorm. Our solar panels, as well as our neighbors’ panels, were unscathed. Yet, several neighbors with metal roofs experienced so much damage from the hail, they had their roofs repaired or replaced.

Editor’s Comment: Like solar panels, metal roofs vary widely in their susceptibility to hail damage. Metal that is thinner, for instance, will dent more easily, as will roofs with a flatter pitch. This manufacturer notes also that the structure of the metal roofing also can exacerbate visible denting from large hail. The flatter the panel structure, the more the dents may show: 

“At Sheffield Metals, we strongly encourage installing panels that have some degree of structure within the flat section of the panel. For example, striations, bead ribs, pencil ribs, or some other rib roller profile will help to conceal some of the potential hail damage. We understand that some consumers are drawn to the look of flat panels, but it’s important to know that even a light hail event can create visible dents on a roof that has strictly flat panels. So, if you live in an area where hailstorms are a concern, you might want to consider adding a rib roller.”

Solar Panels Versus Hurricanes

How well do solar panels hold up in hurricanes? Again, they are usually tested to hold up in hurricane-force winds. Typically they can survive winds of up to 140 miles per hour — 10 mph greater than a category 4 hurricane. When Hurricane Ida hit Louisiana, it was reported that “rooftop solar systems fared better than big energy companies in surviving Hurricane Ida.” 

The energy companies on the Louisiana coast had widespread damage to their infrastructure that took weeks to repair, leaving hundreds of thousands of Louisianans with no power. Not only did solar panels survive the storm, they tended to protect the roofs better than homes without collectors.

Provided the grid is still functioning, solar panels can still produce electricity even in cloudy weather that precedes and follows hurricanes. But often during hurricanes, the grid goes down, and when the grid goes down, most grid-tied solar systems cannot operate. That is where integrating battery backup with solar arrays makes sense.

Joe Emerson is the founder of the Zero Energy Project and adapted this article for Green Builder from this original blog.