To place an electrical device on your roof for three decades and expect it to work flawlessly is a bit demanding. This is why a lot of people wonder if solar panels can withstand heavy winds, especially those caused by hurricanes and cyclones. The good news is that solar panels are designed to hold their ground (or roof) even in winds as strong as 225 km/h.
Let’s take a look at what makes the seemingly simple solar panels so fiercely resistant to wind.
How Do Solar Panels Withstand Heavy Winds?
For what they look like, solar panels are a bit expensive. And that cost comes not only from sophisticated materials and processes, but a ton of research and design work that goes into creating something that can withstand terrifying weather conditions. Solar panels are built using toughened glass that is extremely difficult to break.
Moreover, solar panel manufacturers subject their panels to rigorous testing before officially launching the product. Here are some types of tests conducted on solar panels:
Static Wind Load Test
The most common wind threat faced by solar panels is a strong flow in a single direction for sustained periods of time. During the recent Cyclone Gabrielle, wind speeds in the country reached as high as 165 km/h. For comparison, a wind speed of about 150 km/h is sufficient to move a vehicle.
While solar panels are fixed to a roof or the ground, unlike cars, they are also much lighter in weight. Additionally, solar panels have absolutely no aerodynamic element – the flat surface of the panel may even act as a sail on a boat. This makes the static load test on a panel important. This test involves subjecting the solar panel to a heavy load for a certain period of time.
Static wind load test on a solar panel (source: Wiley Online Library)
In most cases, the direction of wind is somewhat along the length of solar panels and not perpendicular. This is because most solar panels are installed at an angle or flat, and never vertically. Therefore, intuitively it may seem like the wind might just pass along the edges of a panel.
In reality, however, wind enters the passage between a panel and the roof and creates an uplift, pushing the panel away from the roof. This force is usually perpendicular to the panel, threatening to either rip it apart or fling it away from the roof.
This also highlights the importance of good-quality mounting equipment. There have been instances when poor-quality racking has been the main reason for the destruction of a solar panel system, even when the panels used were of excellent quality.
This brings us to the importance of a reputed solar installer. Reliable installers use high-quality equipment throughout the entire project – this means more than just name-brand solar panels, it also includes quality racking, cables, junction boxes, and everything else in a system.
Dynamic Wind Load Test
Although static wind loads are more common, solar panels can often be subject to random, abrupt winds that keep changing direction. To check their resistance to such winds, solar panels have to undergo the dynamic wind load test.
This test involves subjecting panels to high forces from both the ends alternatingly. This mimics the wind forces of abrupt nature, such as a tornado. A typical dynamic loading setup includes vacuum pumps which imitate the bidirectional loading caused by a dynamic wind.
Dynamic wind load testing (source: Winaico)
Wind Tunnel Tests
Aside from the static and dynamic wind testing mentioned above, some manufacturers also test solar panels against high winds that are simulated in wind tunnels.
Solar panel testing in a wind tunnel (source: ASCE library)
Solar Panels and Flying Debris
When we speak about solar panels facing harsh winds, it is often more than winds that the panels face. Winds of extremely high speeds can often uproot objects like road signs and send them flying. These heavier materials travelling at high speeds can strike solar panels. Even when the wind is not flinging stuff at solar panels, bigger hail pieces threaten to break the panel glass.
Thankfully, solar panels don’t use regular glass. They are built using toughened glass, also known as tempered glass, which is up to six times stronger than regular glass. But this does not mean the glass is completely unbreakable.
This is why each solar panel undergoes a hail impact test, which involves throwing large pieces of ice at solar panels at speeds of over 110 km/h.
A typical hail impact tester (source: PSE)
When it comes to hail, solar panels are incredibly resilient objects. In 2017, the city of Denver in the U.S. was hit by a severe hailstorm, damaging vehicles and public property. The hailstorm passed over the National Renewable Energy Laboratory building, which was also battered heavily with hail. The NREL building has a solar power plant with over 3,000 panels.
Impressively, only one out of the 3,000+ solar panels was broken by hail, in just one spot. That is a staggeringly low failure percentage of just 0.03%. Tests revealed that the panel that was broken was subjected to numerous hail pieces striking at a single point at the same moment, causing cracks to develop on the panel. This phenomenon, as you can guess, is surprisingly rare.
In short, it is highly unlikely that hail can damage your solar panels.
Solar Panels Vs Strong Winds in New Zealand
The several tests mentioned in the above sections have rigorous passing criteria. In most cases, solar panels are tested for about 2,400 Pa force, or a wind speed of about 225 km/h. Some governments can even have strict norms for this. For example, the state of Florida in the U.S. requires companies to manufacture panels that can sustain 170 mph (274 km/h) winds.
But what about furious winds in New Zealand?
A quick search tells us that most places in NZ barely receive winds of over 20 km/h speed. But let us speak about storms and cyclones. The highest ever wind speed recorded in New Zealand was way back in 1970, when Mount John in Canterbury was hit with a 250 km/h gust, which is just slightly higher than the 225 km/h capacity of solar panels. But wait, isn’t that a mountain? Correct, it is.
Most homes, and therefore most home solar power systems are located at a lower altitude, where the winds are more merciful. For instance, the highest wind speeds achieved during the recent cyclone Gabrielle were about 165 km/h. And as we just mentioned, solar panels are made to withstand up to 225 km/h of wind speeds, which is a lot more than any house in NZ will ever be subjected to.
Lastly, the Tornado Project notes that 76% of tornadoes have wind speeds of less than 180 km/h. This means that solar panels are quite safe, not just in Aotearoa but worldwide.
Solar panels are extraordinary devices – they can power your home with clean energy for multiple decades, and are also some of the toughest objects in or on your house. While their location of installation and their design may seem susceptible to strong winds, solar panels can withstand terrifying winds of up to 225 km/h, which is much greater than New Zealand’s typical gusts.
As we mentioned earlier, the weakest point of failure can often be the racking and not the panel. It is therefore important to choose an installer who uses high-quality racking equipment and has knowledgeable installation technicians.
My Solar Quotes works with vetted, highly reliable installers in the country, so when you get free quotes through us, you can rest assured that you won’t have to worry about strong winds or any other threats to your solar panels.