Self ballasted celestial tracking apparatus

Abstract

The invention is a wind resistant celestial tracking apparatus that uses gravitational forces acting on the moving elements of the structure to provide overturning resistance. A molded self curing compound, such as reinforced concrete, is used as the structural material that provides the mass, and thus the gravitational overturning resistance that reduces or eliminates the need for a massive ballasted or dug-in foundation. The combination of these features potentially lowers cost significantly over that of tracking apparatuses found in prior art. The invention is appropriate for use in any celestial tracking application with any number of axes of motion, but is particularly useful in two axis solar energy collection systems.

What is claimed is: 
     
         1 . A tracking apparatus, comprising:
 a support structure mounted on a support surface and having a first center of mass;   a tracking assembly rotatably coupled to the support structure about a first axis and having a second center of mass; and   a payload assembly rotatably coupled to the tracking assembly about a second axis transverse to the first axis and having a third center of mass, the payload assembly comprising one or more solar modules,   wherein a net gravitational moment results from gravitational forces acting on the first center of mass, the second center of mass, and the third center of mass about an overturn axis, and   wherein the magnitude of a contribution to the net gravitational moment from the second center of mass and the third center of mass is greater than the magnitude of a contribution from the first center of mass.   
     
     
         2 . The tracking apparatus of  claim 1 , further comprising a contact region having a boundary in contact with one or more contact surfaces, the support structure mounted on the support surface at the one or more contact surfaces, wherein the overturn axis is coincident with one or more points along the boundary of the contact region. 
     
     
         3 . The tracking apparatus of  claim 1 , wherein the tracking assembly is constructed of reinforced concrete. 
     
     
         4 . The tracking apparatus of  claim 1 , wherein the tracking assembly comprises a tilt structure rotatably coupled to the support structure, the tilt structure configured to tilt about the first axis, the first axis comprising a substantially horizontal tilt axis. 
     
     
         5 . The tracking apparatus of  claim 4 , wherein the tracking assembly further comprises a roll structure rotatably coupled between the tilt structure and the payload assembly, the roll structure configured to pivot about the second axis, the second axis comprising a roll axis substantially perpendicular to the tilt axis. 
     
     
         6 . The tracking apparatus of  claim 1 , wherein the tracking assembly comprises an azimuth structure coupled to the support structure, the azimuth structure configured to rotate about the first axis, the first axis comprising an azimuth axis substantially perpendicular to the support surface. 
     
     
         7 . The tracking apparatus of  claim 6 , wherein the tracking assembly further comprises an elevation structure rotatably coupled to the azimuth structure, the payload assembly configured to pivot about the second axis, the second axis comprising a pivot axis transverse to the azimuth axis. 
     
     
         8 . A tracking apparatus comprising:
 a tracking assembly having a first center of mass and configured to rotate about an azimuth axis; and   a payload assembly comprising one or more devices configured to interact with electromagnetic energy, the payload assembly mounted on the tracking assembly and configured to pivot about a pivot axis transverse to the azimuth axis, the payload assembly having a second center of mass,   wherein the first center of mass and the second center of mass are at or near the azimuth axis.   
     
     
         9 . The tracking apparatus of  claim 8 , wherein the tracking assembly comprises an azimuth structure having a third center of mass and an elevation structure having a fourth center of mass, wherein the third center of mass and the fourth center of mass are at or near the azimuth axis. 
     
     
         10 . The tracking apparatus of  claim 9 , wherein the azimuth structure and the elevation structure are constructed substantially of reinforced concrete. 
     
     
         11 . The tracking apparatus of  claim 8 , further comprising a support structure mounted to a support surface and having a fifth center of mass, wherein the tracking assembly is mounted on the support structure. 
     
     
         12 . The tracking apparatus of  claim 11 , wherein the support structure comprises peripheral edges defining overturn axes of the tracking apparatus. 
     
     
         13 . The tracking apparatus of  claim 12 , wherein a net gravitational moment results from gravitational forces acting on the first center of mass, the second center of mass, and the fifth center of mass, and wherein the magnitude of a contribution to the net gravitational moment from the first center of mass and the second center of mass is greater than the magnitude of a contribution from the fifth center of mass. 
     
     
         14 . The tracking apparatus of  claim 12 , wherein a distance between the first center of mass or the second center of mass and any possible overturn axis is about the same. 
     
     
         15 . The tracking apparatus of  claim 13 , wherein the net gravitational moment is greater than and opposite a net wind moment, the net wind moment resulting from a wind pressure profile acting on the tracking apparatus. 
     
     
         16 . The tracking apparatus of  claim 8 , wherein the payload assembly comprises one or more photovoltaic modules. 
     
     
         17 . The tracking apparatus of  claim 8 , further comprising an azimuth actuator coupled to the tracking assembly, the azimuth actuator configured to rotate the tracking assembly about the azimuth axis. 
     
     
         18 . The tracking apparatus of  claim 8 , further comprising a pivot actuator coupling the tracking assembly and the payload assembly, the pivot actuator configured to rotate the payload assembly about the pivot axis relative to the tracking assembly. 
     
     
         19 . A tilt-roll tracking apparatus comprising:
 a support structure mounted on a support surface;   a concrete tilt structure rotatably coupled to the support structure about a substantially horizontal tilt axis;   a roll structure rotatably coupled to the concrete tilt structure about a roll axis transverse to the horizontal tilt axis; and   a payload assembly coupled to the roll structure, the payload assembly comprising one or more devices configured to interact with electromagnetic energy.   
     
     
         20 . The tilt-roll tracking apparatus of  claim 19 , wherein the support structure has a first center of mass, the concrete tilt structure has a second center of mass, and the payload assembly has a third center of mass, and wherein a magnitude of a net contribution to a net gravitational moment about overturn axes of the tilt-roll tracking apparatus from the second center of mass and the third center of mass is greater than a magnitude of a contribution to the net gravitational moment about the overturn axes from the first center of mass.