Does hail damage solar panels in Illinois?

Under certification standards — IEC 61215, with UL 61730 governing safety — every certified module passes a standardized hail test: eleven ice-ball strikes, 25 mm (one inch) in diameter, at about 51 mph, after which the module must show no visible damage and lose less than 5% of its power. The front is usually tempered glass, built to take impacts for decades outdoors. DOE suggests panels with front glass at least 3.2 mm thick: thinner glass, common on two-sided (bifacial) panels, is usually heat-treated instead of tempered, and it is not as strong.

Two honest caveats, straight from the U.S. Department of Energy's hail guidance. That test is the floor, not the ceiling — optional tests exist with larger ice balls at higher speeds, and manufacturers rarely publish those results, so anyone especially worried about hail can ask a manufacturer for written proof of testing above the minimum. And certification screens the design; it is not a guarantee about any specific storm. DOE also says solar modules have survived most hail events so far, but hail larger than 1¾ inches (44 mm) has caused significant damage.

Two very different ways. Visible breakage — shattered or spider-cracked tempered glass — announces itself from the driveway. Microcracks don't: hail can crack the cells under glass that looks fine. At first they may not lower output at all, but DOE says they can spread over time, cutting production and raising the risk of hot spots and fire. Your monitoring data is still the best everyday check, compared against what the system typically produces. After a big storm, ask the inspector about a camera scan for hidden cracks; DOE suggests one within a month.

After any serious hail, pull up a clean-sky day and compare it to similar conditions before the storm. A shortfall with no visible damage is precisely the case where a professional inspection earns its fee — and precisely the case most homeowners miss.

Possibly, for the area they cover — an array can take hits the shingles would have taken, but we found no independent test showing how much protection that is. It is not a force field for the whole roof: after a storm severe enough to damage roofs, both the array and the exposed roofing around it deserve an inspection.

How the mounts, flashing, and roof warranties fit together — including who stands behind the penetrations — is covered in the roof requirements guide.

Commonly, yes, for rooftop systems — panels attached to the house are generally treated as part of the dwelling under a homeowners policy. But "commonly" is not "yours": coverage is whatever your specific policy says, and some policies limit or carve out wind and hail. So the real work happens before install — notify your insurer, and get every answer in writing.

The questions that matter: does the system's replacement cost fit inside your dwelling limits; are hail and wind covered, and does a separate wind/hail deductible apply; what happens to the premium; and — if the system is a ground mount — how would it be classified, since detached systems may fall under a different part of the policy than the roof does. One more, easy to forget: if the system is leased, ask whose policy actually covers it. For a lease under Illinois Shines, the contract must say who insures the system and who pays if it is damaged, so read that part before you sign. Then document the system while it's healthy: photos, serial numbers, invoices, and a monitoring baseline. It's the same file that smooths a future sale — the document pack — and it's exactly what an adjuster will ask for.

Usually that's the wrong door — but check yours. A product warranty covers defects in materials and workmanship; a performance warranty guarantees output stays above a floor over time. Hail is weather, and weather damage typically routes to insurance rather than to either warranty — though terms vary by manufacturer, and no blanket statement substitutes for reading the actual documents.

Before you sign anything (our quote-vetting checklist has the rest of the questions), ask the installer to state in writing how storm damage routes — workmanship warranty, product warranty, or insurance — and keep that letter filed with the warranties themselves.

Five steps, in order: check monitoring against typical production; look the array over from the ground — never climb onto potentially damaged glass over live electrical equipment; photograph the array and roof with dates, damage or not; call your installer for an inspection if output dropped or anything looks wrong (if a different company will do the inspection or repair, check its Illinois records first); and open the insurance conversation within your policy's timelines if there's damage.

Even a no-damage storm is worth two minutes: a dated photo and a monitoring screenshot become the "before" for whatever storm comes next.

Real, occasional, and manageable — hail here rides along with spring and summer thunderstorms. Certification testing targets the one-inch stone; the storm that exceeds it, wrecking roofs and cars across a neighborhood, is the occasional event the insurance layer exists for. Hail is a reason to prepare the three layers below — not a reason to skip solar.

The numbers behind “occasional”: from 2015 through 2025, NOAA’s Storm Events database logged hail of 1 inch or bigger somewhere in Illinois on 19 to 45 days a year. About one in four of those reports was golf-ball size (1¾ inches) or bigger. About one in twelve was 2 inches or bigger, past the 1¾-inch mark DOE links to significant panel damage. These are reports people sent in, so some hail is missed. And it is a statewide count, not the odds for one house. On March 10, 2026, a storm dropped a 6.6-inch hailstone in Kankakee, the largest ever confirmed in Illinois (the old record was 4.75 inches, in 2015), according to the National Weather Service in Chicago. Stones that big are far beyond the 1-inch lab test, which is why the insurance layer matters. Snow and ice are the other weather worry in Illinois: see solar panels in an Illinois winter.