Optical concentrator and cooling system for photovoltaic cells

Abstract

An optical concentrator and cooling system in which a photovoltaic cell array is immersed in a liquid inside an elongated tube having a curved transparent wall for incident radiation, said liquid having a refractive index suitable for concentrating the incident radiation onto the photovoltaic cell array.

What is claimed is: 
     
       1. Apparatus for converting solar radiation to electrical energy comprising: 1. a plurality of solar cells;   2. a tube of elliptical cross section, comprising a transparent wall section having elliptical inner and outer wall surfaces, said solar cells being secured to an inner wall of said tube near one end of the major axis of the elliptical shape opposite said transparent wall section;   3. a liquid surrounding said cells and substantially filling said tube whereby radiation impinging on said transparent wall section is concentrated on said cells through the curved surface of said liquid.   
     
     
       2. The apparatus of claim 1 wherein said tube comprises a transparent curved wall section and a radiation reflecting section whereby radiation entering said tube but not refracted directly to said cells is reflected to said cells. 
     
     
       3. The apparatus of claim 2 wherein said reflecting section is a metal. 
     
     
       4. The apparatus of claim 3 comprising in addition cooling fins secured to said metal. 
     
     
       5. The apparatus of claim 1 comprising in addition reflector surfaces disposed inside said tube effective to concentrate incoming radiation to said cells. .Iadd. 6. A method for converting solar radiation to electrical energy which comprises the steps of (1) passing solar radiation through an elongated transparent curved wall tube of glass or plastic substantially filled with a clear nonconducting liquid having a refractive index suitable for concentrating solar radiation on photovoltaic cells; (2) concentrating said radiation on a plurality of photovoltaic cells mounted in a linear configuration in the axial direction inside of said tube and electrically connected to one another; and (3) thereafter recovering electrical energy from said voltaic cells. .Iaddend. .Iadd. 7. The method of claim 6 wherein the tube is cylindrical. .Iaddend..Iadd. 8. The method of claim 6 wherein the tube is closed. .Iaddend..Iadd. 9. The method of claim 6 wherein the tube has inlet and outlet means. .Iaddend..Iadd. 10. The method of claim 6 wherein the photovoltaic cells are electrically interconnected in parallel, in series, or in combinations thereof. .Iaddend..Iadd. 11. The method of claim 6, 7, 8, 9, or 10 wherein the tube comprises a transparent curved wall section and a radiation reflecting section whereby radiation entering said tube but not refracted directly to said cells is reflected to said cells. .Iaddend..Iadd. 12. The method of claim 6, 7, 8, 9, or 10 wherein a surface of the transparent tube is coated with a non-reflective coating. .Iaddend..Iadd. 13. The method of claim 6, 7, 8, 9 or 10 wherein the solar cells are located near one side of the tube and face the distant side. .Iaddend..Iadd. 14. Apparatus for converting solar radiation to electrical energy comprising: 1. a plurality of solar cells mounted in a linear configuration in the axial direction inside an elongated transparent curved wall tube, and   2. a liquid surrounding said cells and substantially filling said tube whereby radiation impinging on said tube is concentrated on said cells, said liquid having a refractive index suitable for concentrating radiation onto said cells. .Iaddend..Iadd. 15. Apparatus of claim 14 wherein the tube is cylindrical. .Iaddend..Iadd. 16. Apparatus for converting solar radiation to electrical energy comprising:   1. a plurality of solar cells mounted in a linear configuration in the axial direction inside a closed, elongated transparent cylindrical tube, and   2. a clear liquid surrounding said cells and substantially filling said tube whereby radiation impinging on said tube is concentrated on said cells, said liquid having a refractive index suitable for concentrating radiation onto said cells. .Iaddend..Iadd. 17. Apparatus for converting solar radiation to electrical energy comprising:   1. a plurality of solar cells mounted in a linear configuration in the axial direction inside an elongated transparent cylindrical tube with the ends closed for holding liquid and having inlet and outlet means for for circulating a liquid coolant, and   2. a clear liquid surrounding said cells and substantially filling said tube whereby radiation impining on said tube is concentrated on said cells, said liquid having a refractive index suitable for concentrating radiation onto said cells. .Iaddend..Iadd. 18. Apparatus of claim 14, 15, 16, or 17 wherein the solar cells are electrically interconnected in parallel, in series, or in combinations thereof. .Iaddend..Iadd. 19. Apparatus of claim 14, 15, 16, or 17 wherein the solar cells are located near one side of the tube and face the distant side. .Iaddend..Iadd. 20. Apparatus of claim 14, 15, 16, or 17 wherein the tube comprises a transparent curved wall section and a radiation reflecting section whereby radiation entering said tube but not refracted directly to said cells is reflected to said cells. .Iaddend..Iadd. 21. Apparatus of claim 14, 15, 16, or 17 wherein a surface of the transparent tube is coated with a non-reflective coating. .Iaddend..Iadd. 22. Apparatus of claim 14, 15, 16, or 17 wherein the liquid is water, an aromatic hydrocarbon, or an aliphatic hydrocarbon. .Iaddend.