The bearing gives the solar tracker the ability to rotate and track the sun. It is a critical piece of the tracker system because it anchors the torque tube, supports the weight of the torque tubes and array, and prevents the torque tubes from lifting during high winds.

Traditionally, solar trackers came with a cylindrical bearing, but the problems associated with the cylindrical design quickly became apparent with use. For instance, installers could not easily achieve the precise alignment needed by trackers because the cylindrical bearings could not overcome twisting caused by pole bending or ground irregularities.

Recognizing these issues, TrinaTracker’s Research and Development department designed and patented a spherical bearing. The spherical bearing corrects the issues from cylindrical bearings by using three-dimensional articulation rather than two-dimensional axial movement, improving terrain adaptability.

The vertical, horizontal, and axial loads on TrinaTracker’s patented spherical bearing

The spherical bearings can thus prevent excessive twisting of the tubes and posts and can avoid misalignment, unlike cylindrical bearings.

Example of misalignments with cylindrical bearings on twisted posts.

The auto-alignment feature of the spherical bearing design also allows automatic rotation on uneven terrains, which means that the original design – without any additional elements or adjustments – is all that is needed to ensure perfect alignment on uneven, undulating terrains.

The spherical bearing has a long shelf life of 25 years and does not require maintenance because of its superior design and material selection. It uses materials with outstanding mechanical, lubrication, and anti-UV properties:

• Polyoxymethylene, also known as POM, ensures excellent self-lubrication, hydrolysis resistance, and UV resistance.
• Polyamide 6.6 reinforced by 30% glass fibre, abbreviated as PA6.6 GF30, is known for its high strength, rigidity, and stability.
• S420GD-grade structural steel provides excellent thermal performance and UV resistance.

The mix of materials used to create the spherical bearings ensures good wear resistance in all scenarios, including sandy and windy environments.

Because of these features, there have been no reported failures of the spherical bearings even in the first installation of the spherical bearing at Zuera, the 11 MW PV plant located in Zaragoza, Spain, completed 15 years ago in 2008.

Spherical bearings installed in Zuera 11 MW PV plant

Want to find out more about the features of TrinaTracker's patented spherical bearing? Download the 'TrinaTracker Spherical Bearing: Unique Three-Dimensional Long-Lasting Patented Component' white paper today.