Two-Axis Solar Concentrator System

Abstract

A system for use on a surface to collect solar energy from the sun has a stand, a module, and solar collector(s). The stand supportable on the surface has rotational points rotatably supporting the module so it can rotate about a first axis of rotation. A first drive disposed on the stand is operable to provide first rotation, and a cable connected between a hoop pulley of the module and the first drive on the stand can rotate the module about the first axis to direct the solar collector(s) toward the sun. The solar collector(s) disposed on the module can be photovoltaic cells for collecting solar energy. A second drive on the module can rotate an adjacent solar collectors on the module using pulleys and cable. Reflectors on the collectors can focus the sun rays to photovoltaic cells. The second drive can rotate the collectors about a second axis, carried by the first axis, to direct the solar collector(s) toward the sun.

I claim: 
     
         1 . A system for use on a surface to collect solar energy from the sun, the system comprising:
 a stand supportable on the surface and having first opposing ends, the first opposing having first rotation points;   a frame having second opposing ends with second rotational points, the second rotational points rotatably disposed on the first rotational points of the stand, the frame rotatable on the first and second rotational points about a first axis of rotation;   a first drive disposed on the stand and operable to provide first rotation;   a hoop disposed on the frame and defining a curvature about the first axis;   at least one first cable connected between the hoop and the first drive and rotating the frame about the first axis with the hoop in response to the first rotation of the first drive; and   solar collector means affixed to the frame.   
     
     
         2 . The system of  claim 1 , wherein the at least one first cable comprises a pre-stretched wire cable. 
     
     
         3 . The system of  claim 1 , wherein the first drive comprises an encoder, a stepper motor, a linear actuator, a DC motor, an AC motor, a brushless motor, or a brushed motor. 
     
     
         4 . The system of  claim 1 , wherein the first drive comprises a drive pulley having the at least one first cable disposed thereon and being rotatable with the first rotation by the first drive. 
     
     
         5 . The system of  claim 4 , wherein the drive pulley defines a helical groove thereabout in which the at least one first cable at least partially wraps. 
     
     
         6 . The system of  claim 4 , wherein the at least one fir cable comprises:
 A first cable segment having one end affixed to the drive pulley and having an opposing end affixed to the hoop on one side thereof; and   A second cable segment having one end affixed to the drive pulley and having an opposing end affixed to the hoop on an opposing side thereof.   
     
     
         7 . The system of  claim 1 , further comprising a first tensioner tensioning the at least one first cable. 
     
     
         8 . The system of  claim 7 , wherein the first tensioner comprises a turnbuckle disposed in line with the at least one first cable, an idler pulley, a biasing element, a catch biased to grip in tension and release in slack, or a combination thereof. 
     
     
         9 . The system of  claim 1 , further comprising a control system operating the first drive to repeatedly orient a line perpendicular to the frame to fall into a plane defined by the first axis of orientation and the sun. 
     
     
         10 . The system of  claim 1 , wherein the first axis of orientation is configured to orient substantially parallel to a north-south cardinal direction. 
     
     
         11 . The system of  claim 1 , wherein the system further comprises at least one other stand having at least one other frame, the stands positioned end-to-end, the first drive operable to rotate the frames in tandem. 
     
     
         12 . The system of  claim 1 , wherein the solar collector comprises at least one solar photovoltaic disposed on the frame.