As we enter the brunt of hurricane season this September, we’re focusing on Ampacity’s experience designing trackers to withstand varying degrees of wind load severity across the country.
Ampacity uses the American Society of Civil Engineers (ASCE) tables as the baseline for our data in structural design. However, it’s worth noting that the project’s authority having jurisdiction (AHJ) has the right to prescribe a wind rating for a customer that differs from the one set forth in the ASCE tables, if they wish. This is especially common in areas with site-specific case study requirements or in areas that have received more favorable results from local permitting authorities. Ampacity can use either set of values and adjust the tracker’s design to comply with these codes.
Design considerations for windy solar projects
After deciding on a wind rating, Ampacity will assess the needs of the tracker to determine if any special considerations need to be followed. The most common remedy for medium-to-high wind loads is to increase the number of bearing posts per row on exterior rows. Since the exterior rows often act as a sort of barrier for the interior rows, it is often appropriate to bolster the strength of the outer rows to protect the other rows by taking the brunt of the wind event. Adding bearing posts to a module row can be an expensive prospect, but the cost benefits down the road often handsomely outweigh the initial price change. This is because with fewer posts, you will require larger and longer post sizes to account for the extra stress on the fewer foundations. Also, more bearings may alleviate the need for heavy duty (HD) bearings, which can be expensive.
Wind implications on solar tracker height
The last consideration worth highlighting with respect to wind force is the effects of elevated tracker height. Increasing the height of the tracker can be a huge factor in heavy wind areas. There are times when this is simply unavoidable, like when there is a floodplain on-site, but there are other times where, with minimal preparation, the taller tracker heights can be avoided altogether. The immediate benefits of grading a site with extreme topography, for instance, is the ease of installation and reduction of material complexity. By reducing the amount of undulation underneath, the tracker height is kept consistently closer to the ground, which shortens the height requirements of the foundations and limits the amount of specialized materials needed for the problem areas. This also cuts down on installation time since the construction crew can get into a locked rhythm and not have to keep readjusting instruments/tools used to measure and install the tracker. All of this can help cut costs and minimize environmental impacts on high-wind projects, while also allowing for a fast and effective build.
Intense wind forces are some of the most common design hazards encountered around the U.S. by our customers. At Ampacity, we take these wind ratings seriously when designing our projects so that we can confidently give our customers a tracker that will stand the test of time.
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