Solar collectors

Abstract

The invention concerns a solar collector ( 10 ) which has at least one radiation-transmitting prism ( 16 ) which is wedge shaped in cross section. The prism has major side surfaces ( 20, 21 ) converging at an acute angle to a relatively narrow, operatively upper end ( 24 ). The opposite, lower end ( 26 ) of the prism is wider. A refractor ( 18 ) is arranged over the prism to refract solar radiation incident thereon onto the major side surfaces of the prism, as the sun moves relative to the earth, at angles allowing such radiation to enter the prism and be internally reflected therein towards a target at or adjacent the relatively wide end of the prism. The configuration allows high levels of solar concentration to be achieved.

1 . A solar collector comprising:
 at least one radiation-transmitting prisms which is wedge-shaped in cross-section and which has major side surfaces converging at an acute angle to a relatively narrow end of the prism, having an opposite, relatively wide end; and   a refractor arranged over the prism to refract solar radiation incident thereon onto the major side surfaces of the prism, as the sun moves relative to the earth, at angles allowing such radiation to enter the prism and be internally reflected therein towards a target at or adjacent the relatively wide end of the prism.   
   
   
       2 . A solar collector according to  claim 1  comprising a plurality of the prisms assembled side by side with their narrow ends extending parallel to one another. 
   
   
       3 . A solar collector according to  claim 2  wherein the collector is configured for single axis tracking in a plane transverse to the narrow ends of the prisms. 
   
   
       4 . A solar collector according to  claim 3  wherein the narrow ends of the prisms extend N-S in use and the collector is movable to track the sun in an E-W plane during the course of a day. 
   
   
       5 . A collector according to  claim 4  comprising means for rotating the collector about a N-S axis. 
   
   
       6 . A solar collector according to  claim 3  wherein the narrow ends of the prisms extend E-W in use and the collector is movable to track the sun in a N-S plane during the course of a year. 
   
   
       7 . A solar collector according to  claim 6  comprising means for rotating the collector about an E-W axis. 
   
   
       8 . A solar collector according to  claim 1  wherein the refractor is a linear refractor. 
   
   
       9 . A solar collector according to  claim 8  wherein the refractor is a linear Fresnel lens. 
   
   
       10 . A solar collector according to  claim 1  wherein the narrow ends of the prisms are adjacent to or in contact with the refractor. 
   
   
       11 . A solar collection according to  claim 1  wherein the narrow ends of the prism's are spaced from the linear refractor. 
   
   
       12 . A solar collector according to  claim 11  wherein the collector includes a reflector arrangement to reflect radiation incident thereon at angles appropriate for acceptance thereof by the prism for internal reflection therein. 
   
   
       13 . A solar collector according to  claim 12  wherein the reflector arrangement comprises convergent reflectors which stand up from the refractor over the narrow ends of the prisms and are arranged to reflect solar radiation outwardly onto the refractor. 
   
   
       14 . A solar collector according to  claim 2  wherein the collector is located beneath a radiation transmitting cover. 
   
   
       15 . A solar collector according to  claim 2  wherein the prisms are spaced from the refractor and are connected to the refractor by radiation-transmitting side panels. 
   
   
       16 . A solar collector according to  claim 1  comprising a radiation transmitting secondary solar concentrator at the wider end of each prism. 
   
   
       17 . A solar collector according to  claim 16  wherein the secondary solar concentrator has side walls which converge towards one another to a width less than that of the wider end of the prism. 
   
   
       18 . A solar collector according to  claim 17  wherein the side walls are planar or concave. 
   
   
       19 . A solar collector according to  claim 16  wherein the secondary solar collector is made of a material with a higher refractive index than the material of which the prism is made. 
   
   
       20 . A solar collector according to  claim 17  wherein the prism and secondary solar concentrator meet one another at a curved interface. 
   
   
       21 . A solar collector according to  claim 20  wherein a convex surface of the secondary solar concentrator mates with a concave surface of the prism at the interface. 
   
   
       22 . A solar collector according to  claim 1  comprising a PV cell at the wider end of each prism. 
   
   
       23 . A solar collector according to  claim 16  comprising a PV cell at an end of the secondary solar collector remote from the prism. 
   
   
       24 . A solar collector according to  claim 1  comprising a pipe conveying a fluid which is to be heated at the wider end of the prism. 
   
   
       25 . A solar collector according to  claim 16  comprising a pipe conveying a fluid which is to be heated at an end of the secondary solar concentrator remote from the prism. 
   
   
       26 . A solar collector according to  claim 1  wherein each prism is made of glass, acrylic or polystyrene. 
   
   
       27 . A solar collector according to  claim 16  comprising a pipe conveying a fluid which is to be heated at an end of the secondary solar concentrator remote from the prism.