Solar energy reflector array

Abstract

A heliostat which comprises a reflector element and a carrier that is arranged to support the reflector element above a ground plane. A drive means is arranged to impart pivotal drive to the carrier about a fixed, first axis that is, in use of the heliostat, disposed substantially parallel to the ground plane. The heliostat further comprises a means mounting the reflector element to the carrier in a manner which permits pivotal movement of the reflector element with respect to the carrier and about a second axis that is not parallel to the first axis. A drive means arranged to impart pivotal movement to the reflector element about the second axis. The reflector element, which may be flat or curved, may be constituted by a plurality of sub-reflector elements. Also, a plurality of the reflector elements may be supported by a single carrier. A plurality of the above defined heliostats may form a solar energy reflector array with the heliostats being arranged to reflect incident solar radiation to at least one target collector.

1 . A heliostat which comprises: 
 a reflector element,    a carrier that is arranged to support the reflector element above a ground plane,    a drive means arranged in use to impart pivotal drive to the carrier about a fixed, first axis that is, in use of the heliostat, disposed substantially parallel to the ground plane,    means mounting the reflector element to the carrier in a manner which permits pivotal movement of the reflector element with respect to the carrier and about a second axis that is not parallel to the first axis, and    a drive means arranged in use to impart pivotal movement to the reflector element about the second axis.    
     
     
         2 . The heliostat as claimed in  claim 1  wherein the drive means that is arranged to impart pivotal motion of the carrier comprises a first drive means and wherein the drive means that is arranged to impart pivotal movement to the reflector element comprises a second drive means which is separate from the first drive means.  
     
     
         3 . The heliostat as claimed in  claim 1  or  2  wherein the reflector element comprises a glass mirror.  
     
     
         4 . The heliostat as claimed in  claim 1  or  claim 2  wherein the reflector element comprises a metallic mirror.  
     
     
         5 . The heliostat as claimed in any one of the preceding claims wherein the second axis about which the reflector element is pivotally mounted to the carrier is disposed orthogonally with respect to the first axis.  
     
     
         6 . The heliostat as claimed in any one of the preceding claims wherein the reflector element has a polygonal shape.  
     
     
         7 . The heliostat as claimed in any one of the preceding claims wherein the reflector element is mounted to the carrier in a manner such that the second axis lies in a line that passes through two most distant points on the periphery of the reflector element.  
     
     
         8 . The heliostat as claimed in  claim 6  wherein the reflector element has a hexagonal form.  
     
     
         9 . The heliostat as claimed in  claim 8  wherein the hexagonal form of the reflector element comprises three pairs of substantially parallel sides embracing a central rectangular portion and two triangular end portions.  
     
     
         10 . The heliostat as claimed in  claim 9  wherein the sides of the hexagonal configuration are proportioned such that arcs of an imaginary circle that passes through the four corners of the rectangular portion will lie wholly within the triangular end portions and, in the limiting condition, will lie tangential to two adjacent sides of each of the triangular portions.  
     
     
         11 . The heliostat as claimed in any one of the  claims 2  to  10  wherein the first drive means includes a drive shaft that is supported for rotation about an axis that lies parallel to the first axis and which is arranged to impart rotary drive to the heliostat carrier.  
     
     
         12 . The heliostat as claimed in any one of the  claims 2  to  11  wherein the second drive means includes a drive member which is connected to the rear (non-reflecting) side of the reflector element of the heliostat and which is arranged to be driven in a manner to impart pivotal movement to the reflector element about the second axis.  
     
     
         13 . The heliostat as claimed in  claim 12  wherein the drive member is connected to the rear side of the reflector element by way of an adjustable joint.  
     
     
         14 . The heliostat as claimed in any one of the preceding claims wherein the carrier for the reflector element of the heliostat has an arcuate shape and is connected at each of its ends of the reflector element.  
     
     
         15 . The heliostat as claimed in any one of the preceding claims wherein the carrier has a semi-circular shape and has its centre of radius coincident with the geometric centre of the reflecting surface of the reflector element.  
     
     
         16 . The heliostat as claimed in any one of the preceding claims wherein the reflector element has a flat reflecting surface.  
     
     
         17 . The heliostat as claimed in any one of the  claims 1  to  15  wherein the reflector element has a curved reflecting surface.  
     
     
         18 . A solar energy reflector array comprising a plurality of heliostats as claimed in any one of the preceding claims and wherein the heliostats are arranged in rows to reflect incident solar radiation to at least one target collector.  
     
     
         19 . The solar energy reflector array as claimed in  claim 18  when dependant on  claim 11  wherein the carriers of at least some of the heliostats in each row of the array are coupled together by a common said drive shaft.  
     
     
         20 . The solar energy reflector array as claimed in  claim 19  wherein at least some of the first drive means incorporate a single motor for imparting drive to a plurality of the drive shafts.  
     
     
         21 . The solar energy reflector array as claimed in  claim 19  wherein a single motor is employed to impart drive to all of the drive shafts in the heliostat array.  
     
     
         22 . The solar energy reflector array as claimed in any one of  claims 18  to  21  wherein a plurality of the reflector elements within a given row of the array is coupled together by connecting respective ones of the drive members to a common motion translating mechanism which forms a part of the second drive means.  
     
     
         23 . The solar energy reflector array as claimed in  claim 22  wherein means are provided for adjusting the length of the drive members whereby ganged motion translation may be imparted to the plural drive members by adjusting the length of the drive members.  
     
     
         24 . The solar energy reflector array as claimed in  claim 22  wherein means are provided for adjusting the length of the drive members whereby ganged motion translation is imparted to the plural drive members by adjusting the operating plane of the motion translating mechanism to accommodate angular travel of the drive members.