Solar panel arrays are usually placed on rooftops. Positioned to catch the maximum amount of sunlight, in most cases they’re also exposed to high wind loads.
Wind loads are influenced by many things, including panel orientation, angle, and roof pitch. The gap between the panels and roof also figures into the equation. On large flat roofs, vortices can roll off the corners, further increasing wind loads on solar panels located near roof edges.
Rooftop solar is becoming a common feature in residential and commercial neighbourhoods. The Australian / New Zealand wind loading standards are just starting to provide unique design information for solar. And not just where wind is concerned.
Solar panels, especially large-scale arrays, can add to roof weight and earthquake-related structural loads. This usually isn’t an issue for small rooftop setups because structural and wind loads are smaller. Large-scale commercial set-ups and buildings designed specifically for solar, on the other hand, are where things get interesting.
When helping design buildings, wind engineers take a long-range view of wind speed. Maximum design loads are typically set for a one-in-five-hundred-year wind event. For this reason, we can be relatively confident that wind loads won't exceed building design capacity. But solar arrays do add a new complication to well-established structural design.
Developers should know when installing the tops of their buildings with dozens of solar panels that the current Australian / New Zealand standards don't cover all the different solar panel configurations. While our standards play catchup, well-established North American and European standards can be used – where different solar configurations have been codified. For extra peace of mind, specialist advice and wind tunnel tests are always available.
In the drive for renewable energy, solar is set to play an increasingly important role in meeting our energy needs. The global rooftop solar market is forecast to grow by 16 percent each year between now and 2030.
As more solar arrays spring up on rooftops around the country, it’s important we keep a weather eye on the influence of wind flow and avoid worst-case scenarios. This footage from the Netherlands shows just how damaging things can get when wind loading hasn’t been properly calculated or fixings have been improperly installed. Thankfully, we’re not aware of similar failures having occurred in New Zealand. Long may that continue.