Most solar panels come with at least an 80% 25 year power warranty, meaning if they don’t have a failure before that, they’re guaranteed to still produce 80% of their original output after more than two decades. In addition, some panels come with a 25 year product warranty, meaning they’re warrantied against product defects for a very long time.
When you have a photovoltaic system on your roof for that many years, it’s going to eventually experience severe weather. Rain, snow, extreme heat and cold, and gale-force winds (or worse) are all things that solar panels need to withstand if they’re going to continue working for that many years.
But hail is a particular concern. If you live in any of the states known as hail alley - approximately Texas, Oklahoma, Colorado, Kansas, Nebraska and Wyoming - you know that thunderstorms can often whip up significant ice pellets. According to the National Weather Service (NWS), the middle of hail alley experiences an average of 7 to 9 hail events per year.
If you have solar panels, should you worry that they can get damaged by hail? For the most part, no. Solar panels are designed to withstand one inch hail flying at 51 miles per hour. One inch hail (about the size of a quarter) is considered severe by the NWS, so your panels should survive even severe hailstorms just fine.
Here’s a video of what that testing looks like. Be aware that the last two projectiles that shatter the glass are plastic and steel balls, not ice.
In order for a solar panel to be approved by the California Energy Commission, there are a number of certification tests that it must pass.
One of these is IEC 61215, which involves accelerated stress tests to see how well the module holds up under heat, cold, wind, humidity, UV light, and mechnical stress - including hail.
There are two versions of the standard: the original IEC 61215, and a newer IEC 61215:2005. There is a difference in strength rating between the two tests - read more about that later.
The hail test basically involves shooting 25 mm (one inch) ice pellets at 23 meters/second (51 miles per hour) at the panel. If the panel survives 11 such impacts, it passes the test.
According to the National Oceanic & Atmospheric Administration (NOAA), one inch hail is considered severe, and hailstones in a severe thunderstorm would be expected to fall at about 40 mph at most. So, this test exceeds the velocity of hail impacts even in a severe thunderstorm.
It’s a good idea to take a look at the datasheet for the solar panels you intend to install on your home. While the specs can appear complicated, there’s only a few key things to look out for. I wrote a post to help you deciper them.
One of these key things is the strength rating of the panel. There will be two ratings.
The frontside strength, also called the snow load rating, tells you how much force the front of the panel is designed to withstand.
The backside strength, also called the wind load rating, measures the strength of the rear of the panel.
They’re referred to as snow load and wind load because the ability to survive the weight of several feet of snow or heavy winds hitting the back of the panel are common stress scenarios that a solar panel will need to deal with.
The snow load is the relevant rating when it comes to hail. It’s usually listed in Pascals (Pa), a unit of force. Higher numbers are better.
A solar panel with an IEC 61215:2005 rating will have a snow load rating of at least 5,400 Pa and a wind load rating of at least 2,400 Pa. Panels that satisfy the older IEC 61215 standard only need a snow rating of 2,400 Pa.
Solar panel datasheets all look different, so you’ll need to study it for a minute to find the rating. As an example, here’s a portion of the datasheet for the SunPower X-Series:
There are a couple things I’ve highlighted.
First is the IEC 61215 rating. Unfortunately, SunPower hasn’t indicated whether it’s an older version of the standard or the newer 2005 standard.
But below that, you can see the maximium load clearly listed. This particular product has two different frames.
SunPower’s Gen 3 meets the basic standard, but the Gen 5 frame is even stronger with an 8,000 Pa snow load rating. If you live in hail alley or somewhere with severe snowfall, the SunPower X-Series with a Gen 5 frame would be a good choice.
Any solar panel you install on your home today is rated to withstand severe hail, but there are extreme hail events that can damage even the strongest panels. If a thunderstorm starts spitting baseball-sized hail from the sky, there are few structures that will escape unharmed, including solar panels.
So there’s no guarantee that your solar panels will be completely hail-proof.
Still, if you live in hail alley, you might want to consider getting solar panels that exceed the typical 5,400 Pa rating to maximize your chances of having panels that last a full 25 years, or even more.
Here’s a partial list of solar panels that have better than 5,400 Pa snow load ratings.
|Canadian Solar Standard and All-Black||6,000 Pa|
|LG NeON 2||6,000 Pa|
|REC N-Peak||7,000 Pa|
|SolarWorld Sunmodule Plus||8,500 Pa|
|SunPower X-Series and E-Series (Gen 5)||8,000 Pa|
If you live somewhere with lots of snow, frequent hail, or even next door to a baseball diamond, you should factor in solar panel strength ratings to make sure that the product will stand up to hail, several feet of snow, or even flying baseballs.
Look for an IEC 61215 rating on the solar panel specification sheet and a snow load or frontside load rating of at least 5,400 Pa. If you choose a panel with a higher rating, you’ll have an even higher likelihood that your solar array will continue working decades from now.