Terrain following solar tracker
A solar tracker, solar array, and method of designing a solar tracker or array including a plurality of piers, a torque tube supported by the piers, each pier having a common reveal from the earth and the torque tube has a relative angle from a first pier to a second pier of between 0.25 and about 0.75 degrees.
1. A rolling terrain following solar tracker comprising:
a first plurality of piers embedded into rolling terrain and arranged in a row, the first plurality of piers being at differing heights relative to each other due to the rolling terrain;
a torque tube extending along the first plurality of piers at the differing heights relative to each other such that the torque tube substantially follows a contour of the rolling terrain, the torque tube formed of a second plurality of sections, the second plurality of sections being interconnected and having one end which is swaged and another end unswaged such that the swaged ends are inserted in the unswaged ends to form the torque tube, the torque tube passing through a third plurality of bearings that are respectively mounted on the piers at the differing heights, the torque tube extending along the first plurality of piers at the differing heights relative to each other bending and pre-loading the torque tube;
a first section of the second plurality of sections extending from a first pier of the first plurality piers to a second pier of the first plurality of piers; and
a second section of the second plurality of sections extending from the second pier to a third pier of the first plurality of piers, the difference in pier heights causing bending along a length of the first section and pre-loading the first section to form a relative angle between the first section and the second section of between 0.25 and about 0.75 degrees to enable the torque tube to follow contour variations in the rolling terrain.
2. The rolling terrain following solar tracker of claim 1 , wherein a difference in pier height from the first pier to the second pier is between 1.5 and 15 inches.
3. The rolling terrain following solar tracker of claim 1 , wherein a difference in pier height from the first pier to the second pier is between 1.5 and 4.5 inches.
4. The rolling terrain following solar tracker of claim 1 , wherein a maximum north-south slope is between 3.5 and 10 degrees.
5. The rolling terrain following solar tracker of claim 1 , wherein the relative angle between the plurality of piers varies along the torque tube such that the torque tube is substantially parallel to the contour of the rolling terrain.
6. The rolling terrain following solar tracker of claim 1 , wherein relative angles between the first plurality of piers varies along the torque tube such that the torque tube follows elevational variations in the rolling terrain.
7. The rolling terrain following solar tracker of claim 1 , wherein relative angles of each of the second plurality of sections varies along the torque tube such that the bending and pre-loading of the torque tube causes the torque tube to follow elevational variations in rolling terrain.
8. The rolling terrain following solar tracker of claim 1 , wherein the swaged ends inserted into the unswaged ends forms overlapping sections having a double-wall thickness.
9. The rolling terrain following solar tracker of claim 8 , wherein the overlapping sections are placed proximate the piers of the first plurality of piers.
10. The rolling terrain following solar tracker of claim 9 , wherein the overlapping sections are placed proximate the piers of the first plurality of piers where bending moments of the bending of the torque tube are highest.
11. The rolling terrain following solar tracker of claim 1 , wherein the first plurality of piers embedded in the rolling terrain and arranged in the row comprises the first plurality of piers embedded in the row of varying contour.
12. The rolling terrain following solar tracker of claim 1 , wherein the torque tube formed of the second plurality of sections is a pre-loaded continuous torque tube.
13. The rolling terrain following solar tracker of claim 12 , wherein the pre-loaded continuous torque tube passes through the third plurality of bearings that are respectively mounted on the piers at the differing heights.
14. The rolling terrain following solar tracker of claim 12 , wherein a central longitudinal axis of the first section of the continuous torque tube is angularly deflected from a central longitudinal axis of the second section of the continuous torque tube between 0.25 and about 0.75 degrees to enable the torque tube to follow contour variations in the rolling terrain.
15. The rolling terrain following solar tracker of claim 14 , wherein the central longitudinal axis of the first section of the continuous torque tube is angularly deflected from the central longitudinal axis of the second section of the continuous torque tube to cause the central longitudinal axis of the first section of the continuous torque tube to be non-parallel to the central longitudinal axis of the second section of the continuous torque tube.
16. The rolling terrain following solar tracker of claim 1 , wherein the first plurality of piers being at differing heights relative to each other due to the rolling terrain comprises each of the first plurality of piers being at different heights above the rolling terrain.