Solar energy collection system

Abstract

A system for collecting solar energy using a plurality of energy collection elements arranged in a planar array within a stationary base structure, each comprising: an energy capture unit with optical means of focusing directional sunlight parallel to its axis onto one or more sunlight-to-electricity converters within itself, and means of sensing divergence of its axis from the sun's direction; and an angular positioning unit that orients said capture unit about two nested axes by slidably mounting two arcuate tracks in opposed and perpendicular arcuate slots, a convex track within said energy capture unit and a concave track within said base structure, each said slot equipped with a drive apparatus that engages its respective track and moves the positioner along it. The invention provides methods for determining the shapes and arrangement of such elements so as to maximize aperture efficiency while preventing collisions of adjacent elements.

What is claimed is: 
     
         1 . A solar energy collection system comprising an 2-dimensional array of energy-collection elements supported in a base structure, each element equipped with an energy capture unit incorporating light-concentrating optics and light-to-electricity conversion means, a mount permitting tilting of the capture unit about two substantially perpendicular axes, and means of effecting tilt about each such axis;
 wherein the improvement consists of each element's 2-axis mounting and tilt-effecting functions being combined in a compact angular positioning unit that supports and positions the energy capture unit relative to itself by mounting and moving itself along one or more convex arcuate tracks integral to the capture unit, and supports and positions itself relative to the base structure by mounting and moving itself along a concave arcuate track rigidly fixed to said base structure.   
     
     
         2 . The energy-collection element of  claim 1  in which the angular positioning unit contains an arcuate slot that slidably mounts the capture unit's convex track, and a substantially perpendicular arcuate slot that slidably mounts the base unit's concave track. 
     
     
         3 . The energy-collection element of  claim 1  in which the angular positioning unit contains a pair of motor-driven rollers or pinion gears, each engaging one of the said tracks and controlling the travel of the positioning unit along the track. 
     
     
         4 . The energy-collection element of  claim 3  in which the said motors are powered by electricity generated by outward-facing PV cells within the element's energy capture unit. 
     
     
         5 . The energy-collection element of  claim 3  in which the said motors are powered by electricity whose characteristics are controlled as a function of of the multidimensional vector of response levels of each of several power PV cells in the element's energy capture unit. 
     
     
         6 . The energy-collection element of  claim 1  in which the articulation between the angular positioning unit and base-attached concave are allows the former to be removed from and re-installed on the latter through a simple manual action, and where the installation procedure involves no calibration. 
     
     
         7 . The energy-collection element of  claim 1  in which the inner tilt axis, defined by the centers of the arcuate track or tracks in the energy capture unit, and the outer tilt axis, defined by the center of the arcuate track in the base, are perpendicular to each other and intersect. 
     
     
         8 . The energy capture unit of  claim 7  being shaped and designed such that: it has a profile as seen from its normal axis that corresponds to its optics' aperture, and which, except for a small inter-unit gap, tiles the plane with a pattern of the cmm symmetry group; and when moved about its tilt axes under the control of the angular positioning unit, sweeps out a volume whose projection perpendicular to the base lies exactly within the said profile shape. 
     
     
         9 . The solar energy collection system of  claim 1  in which the energy-collection elements cannot collide no matter how they move individually. 
     
     
         10 . The solar energy collection system of  claim 1  in which the base structure is part of an enclosure with a transparent top face that protects the solar collection elements. 
     
     
         11 . A solar energy collection element using light-concentrating optics in conjunction with photovoltaic cells in a rigid energy capture unit supported on a 2-axis mount;
 wherein the improvement consists of implementing closed-loop sun tracking without dedicated sensors by segmenting the capture unit into different capture components having parallel optical axes but each having asymmetric optics, and executing orienting motion based on the real-time pattern of responses of the capture components' cells to off-axis directional light.   
     
     
         12 . The element of  claim 11  in which data derived from measuring the behavior of energy collection elements in a testbed environment is used as the basis for computing orienting motion given real-time cell response data. 
     
     
         13 . A method of creating a concentrating optical unit such that its aperture shape matches its profile shape in a plane perpendicular to its normal axis, and the unit's projection onto the a base plane for any set of tilts provided by a two-axis tracking mount also lies within that shape, by combining multiple optical components each having a different aperture and focal length but sharing a common optical axis and focal point, where said component apertures tile the said shape or section of it. 
     
     
         14 . The method of  claim 13  used to create a reflector where the said optical components comprise patches of multiple paraboloids where the patches form a graph over the said base plane with riser surfaces parallel to said optical axis joining the edges of adjacent patches, and where that graph meets the profile curve within a specified maximum distance from said plane.