Aeroelastic load measurements for solar trackers.

Historically, tests of miniature rigid models in atmospheric boundary layer wind tunnels have been performed to estimate wind loading on single-axis tracker systems. However, some solar trackers are extremely flexible structures that twist and bend in the wind. Even if the tracker has locking mechanisms or multiple drives, there can be significant motion and deflection between locks. Other components of trackers can also deflect, such as piles that sway with the wind.

Both the motion and the deflections can substantially change the wind loading from that obtained from the rigid model wind tunnel tests. The wind patterns that set up around a tracker that twists back and forth differ from those of a tracker that does not move at all. Even if a damper is used to prevent significant oscillations, the trackers may still deflect significantly from the uniform tilt usually tested in the wind tunnel. In this situation, we recommend that the wind loads be directly measured on an aeroelastic model of the solar tracker.

By enhancing the scaled aeroelastic models used to test for instability, CPP Wind can simultaneously determine static and dynamic wind loads on tracker wings and bays, which are then used to calculate loads on torque tubes, piles, and components like rails and panels. This method delivers the most realistic wind loads as it replicates the true motion of the tracker in the field as closely as possible. Initial studies have shown that wind loads from rigid model tests could be conservative at most tilts when compared with loads from aeroelastic tests.

As torque tubes and piles usually drive the cost of the structure for utility-scale PV power plants, avoiding any unnecessary conservatism on the wind loads can significantly affect the plant’s overall cost.

Contact us today to learn more about these studies and the potential impact on your tracking system. For information on our other ground-mount wind loading services, view our Ground-Mount Solar informational flyer.

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