How Hail-Resistant Are Solar Panels Really?

Image: @RACQOfficial

While all solar panels installed on homes in Australia have basic hailstone resistance attributes, some manufacturers take it a step further to provide a bit of extra peace of mind and a competitive edge. But we see some hail storms here that no panel could be expected to survive.

What Standard Level Of Hail Resistance Do Solar Panels Have?

Hail impact testing is mandatory under both Australian and international photovoltaic (PV) standards. For crystalline and thin-film modules, IEC 61215 requires modules to withstand impacts from ice balls measuring 25 mm in diameter at a velocity of 23 m/s (82.8 km/h) at 11 locations across the module under a moderate test (Class MH); or 75 mm in diameter for the severe test (Class SH).

More rigorous, enhanced tests include the Swiss Hail VKF HW4 Standard used by organisations such as Germany’s TÜV Rheinland.

The Glass Factor

A solar panel’s main hail protection is the front cover glass. This is “tempered” glass created by heating normal glass and then rapidly cooling it, making it 4-5 times stronger than regular glass.

The glass also contributes significantly to a panel’s weight. Older solar panels tend to have 3.2 mm cover glass. But over the years, some manufacturers have been reducing front glass thickness. It could be as little as 1.6 mm; but that is usually in double-glass (front and back) and bifacial modules; with the back glass providing extra strength.

Which Panel Manufacturers Offer Enhanced Hailstone Resistance?

The following isn’t an exhaustive list, but shows some residential rooftop example models with enhanced hailstone resistance available in Australia from several manufacturers currently included on the SolarQuotes recommended solar panel brand chart.

As for the difference in kinetic energy per impact, according to REC the ability to withstand 45 mm at 110 km/h represents ten times more per impact than the industry standard baseline of 25mm at 82.8 km/h.

If hailstone resistance is important to you, make sure you check a solar panel’s datasheet carefully as there can be differences between models from the same brand.

Hidden Damage – Microcracks

Something to be aware of is testing doesn’t assess the potential for cell damage below the glass, even when the glass isn’t broken — such as microcracks.

Microcracks are tiny, sometimes invisible fractures to the cells caused by stress. Microcracks can grow over time, causing power loss, creating hotspots, degrading panel performance and potentially leading to safety issues including moisture ingress.

Microcracks in solar panels are best detected using Electroluminescence (EL) imaging, where these and other defects are marked as dark areas.

EL imaging showing microcrack damage (dark areas). Source: Winaico.

When Are The Hailstorm “Seasons” In Australia?

Severe hailstorms can happen at any time of the year under the appropriate atmospheric conditions. But general seasonal trends in each Australian state and territory are:

• New South Wales  & ACT: September to February. Peak activity generally occurs in November and December.
• Victoria: Spring and summer (September to March).
• Queensland: Spring and summer months. South-east Queensland is regarded as a supercell hail “hotspot”.
• South Australia: Mainly occur between October and February.
• Western Australia: Differs depending on the region. Perth: more frequent from May to October. In the north-west, from November to April.
• Tasmania: Not as frequent as on the mainland, but more aligned with storms associated with cooler months.
• Northern Territory: During the wet season, which runs roughly from November to April.

A wild card in all this is climate change. According to a study from UNSW published in July this year, climate change may cause hailstorms to become more frequent and more damaging in some Australian cities; including Sydney, Canberra, Melbourne and Perth.

There’s Hail, And Then There’s Hail

A 25mm hailstone can pack a bit of a punch, 45mm is pretty big (around the diameter of a golf ball) and 75mm huge. But the hailstones seen in Queensland during a severe weather event back in 2020 were monstrous — up to *140 mm*. Forget about the panels, imagine having one of those hit your head.

The Insurance Council of Australia (ICA) declared a catastrophe for damage caused by the 2020 severe weather event that resulted in thousands of motor vehicle and property damage claims.

Check Home And Contents Insurance For Hail Coverage

Regardless of what a solar panel’s hailstone protection rating is, we’ve seen some storms in Australia produce stones that no panel could be expected to pull through unscathed except by luck.

That being the case, make sure you’ve informed your home and contents insurance provider that you have a solar power system, and confirm that hailstorm damage is covered. That call could save you a bundle of bucks if the worst should happen.