Bifacial elongated solar cell devices with internal reflectors

• US 7,394,016 B2
• Filed: 10/11/2005
• Issued: 07/01/2008
• Est. Priority Date: 10/11/2005
• Status: Expired due to Fees

• Current Assignee: Solyndra Residual Trust
• Original Assignee: Solyndra Incorporated
• Inventors: Gronet, Chris M
• Primary Examiner(s): Nguyen; Nam X
• Assistant Examiner(s): BARTON, JEFFREY THOMAS
• Application Number:
  US11/248,789
• Publication Number:
  US 20070079864A1
• Time in Patent Office: 994 Days
• Field of Search: 136243-293
• US Class Current: 136/246
• CPC Class Codes: H01L 31/02008 for solar cells or solar cell modules
• CPC Class Codes: H01L 31/022425 for solar cells
• CPC Class Codes: H01L 31/035281 Shape of the body
• CPC Class Codes: H01L 31/042 PV modules or arrays of single PV cells supporting structures for PV modules H02S20/00
• CPC Class Codes: H01L 31/048 Encapsulation of modules
• CPC Class Codes: H01L 31/0504 specially adapted for series or parallel connection of solar cells in a module
• CPC Class Codes: H01L 31/0508 the interconnection means having a particular shape
• CPC Class Codes: H02S 40/22 Light-reflecting or light-concentrating means directly associated with the PV cell or integrated with the PV cell H01L31/054
• CPC Class Codes: Y02E 10/52 PV systems with concentrators

Abstract

A solar cell assembly comprising a plurality of elongated solar cells, each elongated solar cell in the plurality of elongated solar cells comprising (i) an elongated conductive core configured as a first electrode, (ii) a semiconductor junction circumferentially disposed on the elongated conductive core, and (iii) a transparent conductive oxide layer disposed on the semiconductor junction. Each respective solar cell is bound to a first and second corresponding metal counter-electrode that lies in a groove running lengthwise on the respective elongated solar cell. The solar cell assembly further comprises a plurality of internal reflectors. Each respective internal reflector in the plurality of internal reflectors is configured between a first and second elongated solar cell in the plurality of elongated solar cells such that a portion of the solar light reflected from the respective internal reflector is reflected onto the corresponding first and second elongated cell.

Claims

1. A solar cell assembly comprising:

(A) a plurality of elongated solar cells, wherein elongated solar cells in said plurality of elongated solar cells are arranged in a parallel or a near parallel manner thereby forming a planar array having a first face and a second face; and

(B) a plurality of internal reflectors, wherein each respective internal reflector in the plurality of internal reflectors is configured between an adjacent first and second elongated solar cell in said plurality of elongated solar cells such that a portion of the solar light reflected from the respective internal reflector is reflected onto the adjacent first and second elongated solar cell, wherein a portion of the solar light reflected from the respective internal reflector onto the first elongated solar cell is received from both a side of said solar cell assembly that includes said first face of said planar array and a side of said solar cell assembly that includes said second face of said planar array.

2. The solar cell assembly of claim 1, wherein each elongated solar cell in said plurality of elongated solar cells comprises:

an elongated conductive core configured as a first electrode;

a semiconductor junction circumferentially disposed on said elongated conductive core; and

a transparent conductive oxide layer disposed on said semiconductor junction.

3. The solar cell assembly of claim 1, the solar cell assembly further comprising:

(C) a plurality of metal counter-electrodes, wherein each respective elongated solar cell in said plurality of elongated solar cells is bound to a first corresponding metal counter-electrode in said plurality of metal counter-electrodes such that the first metal counter-electrode lies in a first groove that runs lengthwise on the respective elongated solar cell.

4. The solar cell assembly of claim 1, wherein an internal reflector in said plurality of internal reflectors has a hollow core.

5. The solar cell assembly of claim 1, wherein an internal reflector in said plurality of internal reflectors comprises a plastic casing with a layer of reflective material deposited on said plastic casing.

6. The solar cell assembly of claim 5, wherein the layer of reflective material is polished aluminum, aluminum alloy, silver, nickel or steel.

7. The solar cell assembly of claim 1, wherein an internal reflector in said plurality of internal reflectors is a single piece made out of a reflective material.

8. The solar cell assembly of claim 7, wherein the reflective material is polished aluminum, aluminum alloy, silver, nickel or steel.

9. The solar cell assembly of claim 1, wherein an internal reflector in said plurality of internal reflectors comprises a plastic casing onto which is layered a metal foil tape.

10. The solar cell assembly of claim 9, wherein the metal foil tape is aluminum foil tape.

11. The solar cell assembly of claim 1, wherein a cross-sectional shape of an internal reflector in said plurality of internal reflectors is astroid.

12. The solar cell assembly of claim 1, wherein

a cross-sectional shape of an internal reflector in said plurality of internal reflectors is four-sided;

and

a side of said four-sided cross-sectional shape is linear.

13. The solar cell assembly of claim 1, wherein

a cross-sectional shape of an internal reflector in said plurality of internal reflectors is four-sided;

and

a side of said four-sided cross-sectional shape is parabolic.

14. The solar cell assembly of claim 1, wherein

a cross-sectional shape of an internal reflector in said plurality of internal reflectors is four-sided;

and

a side of said four-sided cross-sectional shape is concave.

15. The solar cell assembly of claim 1, wherein

a cross-sectional shape of an internal reflector in said plurality of internal reflectors is four-sided;

and

a side of said four-sided cross-sectional shape is circular or elliptical.

16. The solar cell assembly of claim 1, wherein

a cross-sectional shape of an internal reflector in said plurality of internal reflectors is four-sided;

and

a side of said four-sided cross-sectional shape defines a diffuse surface on said internal reflector.

17. The solar cell assembly of claim 1, wherein

a cross-sectional shape of an internal reflector in said plurality of internal reflectors is four-sided;

and

a side of said four-sided cross-sectional shape is faceted.

18. The solar cell assembly of claim 3, wherein

each respective elongated solar cell in said plurality of elongated solar cells is bound to a second corresponding metal counter-electrode in said plurality of metal counter-electrodes such that the second metal counter-electrode lies in a second groove that runs lengthwise on the respective elongated solar cell.

19. The solar cell assembly of claim 18, wherein

a first portion of an internal reflector in the plurality of internal reflectors is in electrical communication with the first counter-electrode in the first groove of the first elongated solar cell in said plurality of elongated solar cells that corresponds to said internal reflector;

a second portion of the internal reflector is in electrical communication with the second counter-electrode in the second groove of the second elongated solar cell in said plurality of elongated solar cells that corresponds to said internal reflector; and

the first portion of the internal reflector and the second portion of the internal reflector are electrically isolated from each other.

20. The solar cell assembly of claim 19, wherein said internal reflector is sealed to said first counter-electrode and said second counter-electrode by an electrically conductive glue or ink.

21. The solar cell assembly of claim 19, wherein the internal reflector comprises an insulative core with a layer of reflective material deposited on said insulative core, and wherein

the first portion of the internal reflector is a first portion of the layer of reflective material;

the second portion of the internal reflector is a second portion of the layer of reflective material; and

the first portion and the second portion of the internal reflector are electrically isolated from each other by a first and second break in the layer of reflective material.

22. The solar cell assembly of claim 1, wherein

a first portion of an internal reflector in the plurality of internal reflectors is in electrical communication with the first elongated solar cell in said plurality of elongated solar cells that corresponds to said internal reflector;

a second portion of the internal reflector is in electrical communication with the second elongated solar cell in said plurality of elongated solar cells that corresponds to said internal reflector; and

the first portion of the internal reflector and the second portion of the internal reflector are electrically isolated from each other.

23. The solar cell assembly of claim 22, wherein said internal reflector is sealed to said first elongated solar cell and said second elongated solar cell by an electrically conductive glue or ink.

24. The solar cell assembly of claim 22, wherein the internal reflector comprises an insulative core with a layer of reflective material deposited on said insulative core, and wherein

the first portion of the internal reflector is a first portion of the layer of reflective material;

the second portion of the internal reflector is a second portion of the layer of reflective material; and

the first portion and the second portion of the internal reflector are electrically isolated from each other by a first and second break in the layer of reflective material.

25. The solar cell assembly of claim 18, wherein an internal reflector in the plurality of internal reflectors has a first edge and a second edge, wherein said first edge and said second edge run lengthwise along said internal reflector;

and wherein

(i) the first edge of the internal reflector contacts the first counter-electrode in the first groove of the first elongated solar cell in said plurality of elongated solar cells that corresponds to said internal reflector; and

(ii) the second edge of the internal reflector contacts the second counter-electrode in the second groove of the second elongated solar cell in said plurality of elongated solar cells that corresponds to said internal reflector.

26. The solar cell assembly of claim 25, wherein said first edge is sealed to said first counter-electrode and said second edge is sealed to said second counter-electrode by an electrically conductive glue or ink.

29. The solar cell assembly of claim 1, wherein an internal reflector in the plurality of internal reflectors has a first edge and a second edge, wherein said first edge and said second edge run lengthwise along said internal reflector;

and wherein

(i) the first edge of the internal reflector contacts the first elongated solar cell in said plurality of elongated solar cells that corresponds to said internal reflector; and

(ii) the second edge of the internal reflector contacts the second elongated solar cell in said plurality of elongated solar cells that corresponds to said internal reflector.

30. The solar cell assembly of claim 29, wherein said first edge is sealed to said first elongated solar cell and said second edge is sealed to said second elongated solar cell by an electrically conductive glue or ink.

31. The solar cell assembly of claim 29, wherein said first edge is sealed to said first elongated solar cell and said second edge is sealed to said second elongated solar cell by a transparent insulator.

32. The solar cell assembly of claim 31, wherein said transparent insulator is ethylene vinyl acetate or spray Teflon.

33. The solar cell assembly of claim 1, wherein a cross-sectional shape of all or a portion of the elongated solar cells in said plurality of elongated solar cells is oval.

34. The solar cell assembly of claim 1, wherein a length of an elongated solar cell in said plurality of elongated solar cells is between 0.5 meters and 2 meters.

35. The solar cell assembly of claim 3, wherein a cross-sectional area of a metal counter-electrode in said plurality of metal counter-electrodes is between 0.5 square millimeters and 1.5 square millimeters.

36. The solar cell assembly of claim 1, wherein a first elongated solar cell and a second elongated solar cell in the plurality of elongated solar cells are electrically connected in series.

37. The solar cell assembly of claim 1, wherein

said plurality of elongated solar cells is configured to receive direct light from said first face and said second face of said planar array.

38. The solar cell assembly of claim 2, wherein the semiconductor junction of an elongated solar cell in said plurality of elongated solar cells is a homojunction, a heterojunction, a heteroface junction, a buried homojunction, or a p-i-n junction.

39. The solar cell assembly of claim 2, wherein there is an intrinsic layer disposed between the semiconductor junction and the transparent conductive oxide in an elongated solar cell in said plurality of elongated solar cells.

40. The solar cell assembly of claim 39, wherein the intrinsic layer is formed by an undoped transparent oxide.

41. The solar cell assembly of claim 39, wherein the intrinsic layer is made of metal oxide.

42. The solar cell assembly of claim 2, wherein the semiconductor junction of an elongated solar cell in the plurality of elongated solar cells comprises:

an inner coaxial layer; and

an outer coaxial layer,

wherein said outer coaxial layer comprises a first conductivity type and said inner coaxial layer comprises a second, opposite, conductivity type.

43. The solar cell assembly of claim 42, wherein said inner coaxial layer comprises copper-indium-gallium-diselenide (CIGS).

44. The solar cell assembly of claim 42, wherein said outer coaxial layer comprises CdS, SnO₂, ZnO, ZrO₂, or doped ZnO.

45. The solar cell assembly of claim 2, wherein said elongated conductive core is made of aluminum, molybdenum, steel, nickel, silver, gold, an alloy thereof, or any combination thereof.

46. The solar cell assembly of claim 2, wherein the transparent conductive oxide layer of an elongated solar cell in said plurality of elongated solar cells is made of tin oxide SnO_x, with or without fluorine doping, indiumtin oxide (ITO), indium-zinc oxide, doped zinc oxide (ZnO) or a combination thereof.

47. The solar cell assembly of claim 2, wherein the elongated conductive core of all or a portion of the elongated solar cells in the plurality of elongated solar cells is hollowed.

48. The solar cell assembly of claim 47, where air, nitrogen, or helium is blown through all or a portion of the elongated solar cells in the plurality of elongated solar cells.

49. The solar cell assembly of claim 1, wherein an elongated solar cell in said plurality of elongated solar cells is rod-shaped.

50. The solar cell assembly of claim 2, wherein an elongated solar cell in said plurality of elongated solar cells further comprises an antireflective coating that is circumferentially disposed on the transparent conductive oxide layer of the elongated solar cell.

51. The solar cell assembly of claim 50, wherein said antireflective coating is made of MgF₂.

52. The solar cell assembly of claim 2, wherein the elongated conductive core of an elongated solar cell in said plurality of elongated solar cells comprises:

an inner core made of a nonmetallic material; and

a conductive outer core circumferentially disposed on said inner core.

53. The solar cell assembly of claim 52, wherein said inner core is tubing.

54. The solar cell assembly of claim 52, wherein said inner core is made of polybenzamidazole, polymide, polytetrafluoroethylene, polyetheretherketone, polyamide-imide, glass-based phenolic, polystyrene, cross-linked polystyrene, polyester, polycarbonate, polyethylene, polyethylene, acrylonitrile-butadiene-styrene, polytetrafluoro-ethylene, polymethacrylate, nylon 6,6, cellulose acetate butyrate, cellulose acetate, rigid vinyl, plasticized vinyl, or polypropylene.

55. The solar cell assembly of claim 52, wherein said inner core is glass tubing.

56. A plurality of solar cell assemblies, each solar cell assembly in the plurality of solar cells assemblies having the structure of the solar cell assembly of claim 1, wherein solar cell assemblies in said plurality of solar assemblies are arranged in rows on a surface having an albedo that exceeds 80%.

57. A plurality of solar cell assemblies, each solar cell assembly in the plurality of solar cells assemblies having the structure of the solar cell assembly of claim 1, wherein solar cell assemblies in said plurality of solar assemblies are arranged on a surface having an albedo that exceeds 95%.

58. A plurality of solar cell assemblies, each solar cell assembly in the plurality of solar cells assemblies having the structure of the solar cell assembly of claim 1, wherein solar cell assemblies in said plurality of solar assemblies are arranged on a Lambertian, diffuse or involute reflector surface.

59. The plurality of solar cell assemblies of claim 58 wherein the Lambertian, diffuse or involute reflector surface is painted white.

60. The solar cell assembly of claim 2, wherein an elongated conductive core of an elongated solar cell in said plurality of elongated solar cells is metal tubing.

61. The solar cell assembly of claim 1, wherein each elongated solar cell in said plurality of elongated solar cells comprises:

an elongated conductive core configured as a first electrode, wherein a terminal lead is attached to said first electrode; and

a semiconductor junction circumferentially disposed on said elongated conductive core.

62. The solar cell assembly of claim 61, wherein a transparent conductive oxide layer is disposed on each said semiconductor junction.

63. The solar cell assembly of claim 61, wherein the solar cell assembly further comprises:

(C) a plurality of metal counter-electrodes, wherein each respective elongated solar cell in said plurality of elongated solar cells is bound to a first corresponding metal counter-electrode and a second corresponding metal counter-electrode in said plurality of metal counter-electrodes such that;

the first corresponding metal counter-electrode lies in a first groove that runs lengthwise on the respective elongated solar cell; and

the second corresponding metal counter-electrode lies in a second groove that runs lengthwise on the respective elongated solar cell; and

(D) a plurality of electrical contacts, each electrical contact in said plurality of electrical contacts electrically contacting the metal counter-electrodes of a first elongated solar cell in said plurality of elongated solar cells with the terminal lead that is attached to the first electrode of a second elongated solar cell in said plurality of elongated solar cells.

64. The solar cell assembly of claim 63, wherein the plurality of electrical contacts are embedded in a circuit board that attaches to an end of the solar cell assembly.

65. The solar cell assembly of claim 63, wherein

first portion of the plurality of the plurality of electrical contacts are embedded in a first circuit board that attaches to a first end of the solar cell assembly;

and

a second portion of the plurality of electrical contacts are embedded in a second circuit board that attaches to a second end of the solar cell assembly.

66. The solar cell assembly of claim 61, wherein

a first portion of each respective internal reflector in the plurality of internal reflectors is in electrical communication with the first elongated solar cell in said plurality of elongated solar cells that corresponds to said respective internal reflector, wherein the first portion of each respective internal reflector in the plurality of internal reflectors serves as a first counter-electrode to the first elongated solar cell in said plurality of elongated solar cells that corresponds to said respective internal reflector;

a second portion of each respective internal reflector in the plurality of internal reflectors is in electrical communication with the second elongated solar cell in said plurality of elongated solar cells that corresponds to said internal reflector;

wherein the second portion of each respective internal reflector in the plurality of internal reflectors serves as a second counter-electrode to the second elongated solar cell in said plurality of elongated solar cells that corresponds to said respective internal reflector; and

wherein

the first portion and the second portion of each respective internal reflector in said plurality of internal reflectors are electrically isolated from each other.

67. The solar cell assembly of claim 66, wherein the solar cell assembly further comprises:

(C) a plurality of electrical contacts, each electrical contact in said plurality of electrical contacts electrically contacting the first and second counter-electrodes of a first elongated solar cell in said plurality of elongated solar cells with the terminal lead that is attached to the first electrode of a second elongated solar cell in said plurality of elongated solar cells.

68. The solar cell assembly of claim 67, wherein the plurality of electrical contacts are embedded in a circuit board that attaches to a first end of the solar cell assembly.

69. The solar cell assembly of claim 67, wherein

a first portion of the plurality of electrical contacts are embedded in a first circuit board that attaches to a first end of the solar cell assembly;

and

a second portion of the plurality of electrical contacts are embedded in a second circuit board that attaches to a second end of the solar cell assembly.

70. The solar cell assembly of claim 1, wherein a cross-sectional shape of an internal reflector in said plurality of internal reflectors is four-sided and wherein a side of said four-sided cross-sectional shape is the involute of a cross-sectional shape of an elongated solar cell in said plurality of elongated solar cells.

27. The solar cell assembly of 25, wherein said first edge is sealed to said first counter-electrode and said second edge is sealed to said second counter-electrode by a transparent insulator.

28. The solar cell assembly of claim 27, wherein said transparent insulator is ethylene vinyl acetate or spray Teflon.

71. A solar cell assembly comprising:

(A) a plurality of elongated solar cells, each elongated solar cell in said plurality of elongated solar cells comprising;

an elongated conductive core configured as a first electrode;

a semiconductor junction circumferentially disposed on said elongated conductive core; and

a transparent conductive oxide layer disposed on said semiconductor junction;

wherein elongated solar cells in said plurality of elongated solar cells are arranged in a parallel or a near parallel manner thereby forming a planar array having a first face and a second face;

(B) a plurality of metal counter-electrodes, wherein each respective elongated solar cell in said plurality of elongated solar cells is bound to a first corresponding metal counter-electrode and a second corresponding metal counter-electrode in said plurality of metal counter-electrodes such that

the first corresponding metal counter-electrode lies in a first groove that runs lengthwise on the respective elongated solar cell; and

the second corresponding metal counter-electrode lies in a second groove that runs lengthwise on the respective elongated solar cell; and

(C) a plurality of internal reflectors, wherein each respective internal reflector in the plurality of internal reflectors is configured between a corresponding first and second elongated solar cell in said plurality of elongated solar cells such that a portion of the solar light reflected from the respective internal reflector is reflected onto the corresponding first and second elongated solar cell.

72. A solar cell assembly comprising:

(A) a plurality of elongated solar cells, each elongated solar cell in said plurality of elongated solar cells comprising;

an elongated conductive core configured as a first electrode;

a semiconductor junction circumferentially disposed on said elongated conductive core;

an intrinsic layer circumferentially disposed on said semiconductor junction; and

a transparent conductive oxide layer disposed on said intrinsic layer;

wherein elongated solar cells in said plurality of elongated solar cells are arranged in a parallel or a near parallel manner thereby forming a planar array having a first face and a second face;

(B) a plurality of metal counter-electrodes, wherein each respective elongated solar cell in said plurality of elongated solar cells is bound to a first corresponding metal counter-electrode and a second corresponding metal counter-electrode in said plurality of metal counter-electrodes such that

the first corresponding metal counter-electrode lies in a first groove that runs lengthwise on the respective elongated solar cell; and

the second corresponding metal counter-electrode lies in a second groove that runs lengthwise on the respective elongated solar cell;

(C) a plurality of internal reflectors, wherein each respective internal reflector in the plurality of internal reflectors is configured between a corresponding first and second elongated solar cell in said plurality of elongated solar cells such that a portion of the solar light reflected from the respective internal reflector is reflected onto the corresponding first and second elongated solar cell;

(D) a transparent electrically insulating substrate that covers all or a portion of said first face of said planar array; and

(E) a transparent insulating covering disposed on said second face of said planar array, thereby encasing said plurality of elongated solar cells between said transparent insulating covering and said transparent electrically insulating substrate.

73. A solar cell assembly comprising:

(A) a plurality of elongated solar cells, each elongated solar cell in said plurality of elongated solar cells comprising;

an elongated conductive core configured as a first electrode;

a semiconductor junction circumferentially disposed on said elongated conductive core; and

a transparent conductive oxide layer disposed on said semiconductor junction;

wherein elongated solar cells in said plurality of elongated solar cells are arranged in a parallel or a near parallel manner thereby forming a planar array having a first face and a second face;

(B) a plurality of metal counter-electrodes, wherein each respective elongated solar cell in said plurality of elongated solar cells is bound to a first corresponding metal counter-electrode and a second corresponding metal counter-electrode in said plurality of metal counter-electrodes such that

the first corresponding metal counter-electrode is bonded to the elongated solar cell by a first bead of deposited metal that runs lengthwise on the respective elongated solar cell; and

the second corresponding metal counter-electrode is bonded to the elongated solar cell by a second bead of deposited metal that runs lengthwise on the respective elongated solar cell;

(C) a plurality of internal reflectors, wherein each respective internal reflector in the plurality of internal reflectors is configured between a corresponding first and second elongated solar cell in said plurality of elongated solar cells such that a portion of the solar light reflected from the respective internal reflector is reflected onto the corresponding first and second elongated solar cell;

(D) a transparent electrically insulating substrate that covers all or a portion of said first face of said planar array; and

(E) a transparent insulating covering disposed on said second face of said planar array, thereby encasing said plurality of elongated solar cells between said transparent insulating covering and said transparent electrically insulating substrate.

74. The solar cell assembly of claim 73, wherein an internal reflector in the plurality of internal reflectors is in electrical communication with:

(i) a first counter-electrode of a first elongated solar cell in said plurality of elongated solar cells that corresponds to said internal reflector; and

(ii) a second counter-electrode of a second elongated solar cell in said plurality of elongated solar cells that corresponds to said internal reflector.

75. The solar cell assembly of claim 74, wherein said internal reflector is sealed to said first counter-electrode and said second counter-electrode by an electrically conductive glue or ink.

76. The solar cell assembly of claim 74, wherein said internal reflector has a first portion and a second portion, wherein

the first portion of the internal reflector is in electrical communication with the first counter-electrode;

the second portion of the internal reflector is in electrical communication with the second counter-electrode; and

the first portion and the second portion of the internal reflector are electrically isolated from each other.

77. The solar cell assembly of claim 76, wherein the first portion and the second portion of the internal reflector are electrically isolated from each other by an electrically insulative portion.

78. The solar cell assembly of claim 76, wherein the internal reflector comprises an insulative core with a layer of reflective material deposited on said insulative core, and wherein

the first portion of the internal reflector is a first portion of the layer of reflective material;

the second portion of the internal reflector is a second portion of the layer of reflective material; and

the first portion and the second portion of the internal reflector are electrically isolated from each other by a first and second break in the layer of reflective material.

79. The solar cell assembly of claim 74, wherein an internal reflector in the plurality of internal reflectors has a first edge and a second edge, wherein said first edge and said second edge run lengthwise along said internal reflector;

and wherein

(i) the first edge of the internal reflector contacts a first metal counter-electrode of a first elongated solar cell in said plurality of elongated solar cells that corresponds to said internal reflector; and

(i) the second edge of the internal reflector contacts a second metal counter-electrode of a second elongated solar cell in said plurality of elongated solar cells that corresponds to said internal reflector.

80. The solar cell assembly of claim 79, wherein said first edge is sealed to said first counter-electrode and said second edge is sealed to said second counter-electrode by an electrically conductive glue or ink.