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Solar Panel Snow And Hail Damage

Most solar panels get through winter and hail seasons fine. When they do not, the damage is not always visible from the ground. This guide uses Department of Energy pages and a DOE owner's guide, written mainly for federal facility managers, so apply it as general background and not as a rule for your roof.

How Often Hail Causes Damage

The Department of Energy Federal Energy Management Program page on hail damage says that historically solar modules have survived the majority of hail events they have experienced, but that in areas with very large hail (greater than 1 3/4 inches or 44 millimeters in diameter) hail has caused significant damage. It also says severe hail is the greatest contributor to insured losses on solar PV systems worldwide.

What Snow And Ice Can Do

The Department of Energy Federal Energy Management Program page on winter weather and solar says most snow melts quickly off PV systems or is blown off by wind, but that during severe snowstorms the weight of accumulated snow may cause a module to warp or even break. It adds that ice can add and redistribute weight, potentially over straining module frames and the structure that supports them.

Do Not Climb Up Or Scrape

For a coming storm, the winter page says to remove existing snow only if there is substantial accumulation and a risk of overloading, and to use a broom and not a shovel. The Department of Energy PV System Owner's Guide to weather vulnerabilities (September 2021) says auditors should never walk, climb, or lean on any modules. It also warns that snow removal crews can easily miss low tilt, flush mounted arrays that are covered and end up walking onto the modules or damaging them with shovels. If you have a roof array, leave it to a professional.

After The Storm

For facility managers, the winter page's pre-storm list includes powering the system down and inspecting after the storm before powering back on. For a home system, ask your installer how that is done on your equipment before touching any switch. The page also says that in places prone to extreme winter weather a trained professional should inspect after each winter or after an extreme event. It lists checking for broken glass, detached metal frames, and warped modules, then confirming that modules are still secure, cables are still routed securely, and production is as expected. If damage is found, it says the system should be disconnected and corrective repairs made, including replacing damaged modules.

Why A Cracked Panel Still Matters

The owner's guide says damage can be broken glass but is often microcracking of the cells, which is found with infrared or electroluminescence imaging, and that modules with extensive microcracking may not suffer serious long term power loss. It also says cracked cells or glass may still perform to expected levels but will start to worsen over time, and that water intrusion through broken glass or cracked backsheets can create electrical faults within the modules. So a panel that still produces is not a reason to skip an inspection.

Ratings Worth Knowing

• The owner's guide says most modules are rated for a 2,400 pascal front pressure under ASTM E1830-15, and that systems in severe weather regions should have modules rated for wind and snow loads of 3,600 to 5,000 pascals or more.
• The owner's guide says wind load tolerance is also influenced by the mounting, clamping, and stiffness of the racking, so check the module installation manual and ask your installer about your layout.

Steps For Owners

1. Photograph visible damage from the ground, with dates, and save your production history.
2. Look at your monitoring data for a drop after the storm. See Solar System Not Producing.
3. Call your homeowner's insurer about the damage before repairs, and ask what they need documented. We do not know your policy.
4. Have a licensed solar service company inspect, and ask for written findings.
5. If water shows inside near the array, read Roof Leak Around Solar Panels.

If you want a local service company to look at your system, describe it in the system check form. We name the one company before anyone contacts you.

Related: Solar System Not Producing, Roof Leak Around Solar Panels, Solar Monitoring, Repair, And Inspection, Solar Warranty Help.