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Accurate Geometry is the First Step in Wind Tunnel Testing Solar Trackers


Horizontal single-axis trackers (HSATs) are susceptible to wind-induced damages, and wind loading on these solar trackers is one of the primary considerations in their design. The best way to understand these wind loads is to perform a scaled-model wind tunnel test of a small array of trackers (typically 1:30 or 1:50 scale).

Wind tunnel testing standards[1] require architectural details that extend 2% or more of the least horizontal dimension in full-scale are included in the wind tunnel model. HSATs typically feature a torque tube or dual-rail support structure protruding 0.1 m to 0.2 m below the plane of the PV panels. CPP Wind’s experience in peer-reviewing wind tunnel studies on solar trackers from around the world suggests these support structures are often excluded from the miniature model.

At CPP Wind, we have performed wind tunnel tests on HSATs with either a torque tube or dual-rail support structure and compared the wind loads with bare panels without any support structure underneath. A wide range of panel tilts and wind azimuths have been tested to capture these structures’ effect on wind loads properly. Moments significantly increase with a support structure underneath, especially at low tilts (0° to 10°). This increase is due to the structure altering the distribution of wind pressures along the chord of the system. The location of the structure (distance from the edge of the panel) is essential as it can affect the flow not just underneath the PV panels but also the flow over the top surface.

The design wind loads could be significantly worse for trackers with a low-tilt stow strategy if the support structure was not modeled in the wind tunnel tests. Details of a study performed by CPP Wind can be found here.

To ensure the success of your solar tracker, contact CPP Wind to discuss the potential aerodynamic impacts of changes to your solar tracker’s structural support system and evaluate the potential impact on the wind loads. If you’ve previously tested your system and are concerned about the results, we can also perform a peer review of an existing study to determine if new wind loads are needed.

Take the first step in wind tunnel testing your solar tracking system and contact the experts at CPP Wind.

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[1] Wind Tunnel Testing for Buildings and Other Structures, American Society of Civil Engineers (ASCE/SEI 49-21)