Among the many factors that influence the wind loads on a roof, parapet heights are one of the most counterintuitive. Naturally, one would think that parapets serve to obstruct wind gusts from reaching solar panels. However, this interaction is more complex, and wind loads are generally found to increase with higher parapet walls. Increased parapet heights tend to directly impact the size of wind vortices formed at building corners and as a result, produce faster wind flows above the roof surface. Known as the “Parapet Effect”, this is influenced by other factors, including panel row spacing, tilt angle, array geometry and location on the roof. Without further research, the influence of the Parapet Effect is usually over-estimated and in turn, design engineers have to over-ballast solar rooftop systems to ensure all complex wind flows are accounted for.
Continuous improvement at KB Racking involves an awareness of the latest research, news, and technologies that drive the solar industry. A recent study, by Browne et al, on the wind loads of rooftop solar systems has led us to explore the Parapet Effect in more depth by investing in additional wind tunnel research. The results of the research study can produce unique advantages, especially for weight-challenged roofs.
The greatest of these advantages, is the practice of calculating wind loads for specific wind directions as well as the area of an array. These considerations ensure that every array, for each project, is being ballasted individually and accurately – eliminating needless over-ballasting. As a result, this new method to calculate wind loads allows KB Racking to engineer ballasted systems with lower weight requirements for the EkonoRack and AeroRack rooftop mounting solutions. This study is just one example of KB Racking’s dedication to continuous research and development in order to provide our customers with custom engineered solutions that are built to last.