Elongated photovoltaic cells in casings

• US 20070215197A1
• Filed: 05/03/2007
• Published: 09/20/2007
• Est. Priority Date: 03/18/2006
• Status: Abandoned Application

• Current Assignee: Solyndra Residual Trust
• Original Assignee: Solyndra Residual Trust
• Inventors: Morad, Ratson, Buller, Benyamin, Beck, Markus, Gronet, Christian
• Application Number:
  US11/800,089
• Publication Number:
  US 20070215197A1
• Time in Patent Office: Days
• US Class Current: 136/243
• CPC Class Codes: H01L 31/0203 Containers; Encapsulations , e.g. encapsulation of photodiodesfor photovoltaic devices H01L31/048; for organic photosensitive devices H10K30/80
• CPC Class Codes: H01L 31/02168 the coatings being antireflective or having enhancing optical properties for the solar cells
• CPC Class Codes: H01L 31/022433 Particular geometry of the grid contacts
• CPC Class Codes: H01L 31/035281 Shape of the body
• CPC Class Codes: H01L 31/052 Cooling means directly associated or integrated with the PV cell, e.g. integrated Peltier elements for active cooling or heat sinks directly associated with the PV cells cooling means in combination with the PV module H02S40/42
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

A solar cell unit having a solar cell and a transparent casing circumferentially disposed onto the solar cell is provided. The solar cell has a substrate, where at least a portion of the substrate is rigid and nonplanar. A back-electrode is circumferentially disposed on the substrate. A semiconductor junction layer is circumferentially disposed on the back-electrode. A transparent conductive layer is circumferentially disposed on the semiconductor junction.

Claims

1. A solar cell unit comprising:

(A) a solar cell, said solar cell comprising;

a substrate, wherein at least a portion of said substrate is rigid and nonplanar;

a back-electrode circumferentially disposed on the substrate;

a semiconductor junction layer circumferentially disposed on said back-electrode; and

a transparent conductive layer circumferentially disposed on said semiconductor junction; and

(B) a transparent casing circumferentially disposed onto said solar cell.

2. The solar cell unit of claim 1, wherein the transparent casing is made of plastic or glass.

3. The solar cell unit of claim 1, wherein the transparent casing comprises aluminosilicate glass, borosilicate glass, dichroic glass, germanium/semiconductor glass, glass ceramic, silicate/fused silica glass, soda lime glass, quartz glass, chalcogenide/sulphide glass, fluoride glass, flint glass, or cereated glass.

4. The solar cell unit of claim 1, wherein the transparent casing comprises a urethane polymer, an acrylic polymer, a fluoropolymer, a silicone, a silicone gel, an epoxy, a polyamide, or a polyolefin.

5. The solar cell unit of claim 1, wherein the transparent casing comprises polymethylmethacrylate (PMMA), poly-dimethyl siloxane (PDMS), ethylene vinyl acetate (EVA), perfluoroalkoxy fluorocarbon (PFA), nylon, cross-linked polyethylene (PEX), polypropylene (PP), polyethylene terephtalate glycol (PETG), polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), or polyvinylidene fluoride (PVDF).

6. The solar cell unit of claim 1, wherein the substrate comprises plastic or glass.

7. The solar cell unit of claim 1, wherein the substrate comprises metal or metal alloy.

8. The solar cell unit of claim 1, wherein the substrate comprises soda lime glass.

9. The solar cell unit of claim 1, wherein the substrate comprises aluminosilicate glass, borosilicate glass, dichroic glass, germanium/semiconductor glass, glass ceramic, silicate/fused silica glass, quartz glass, chalcogenide/sulphide glass, fluoride glass, a glass-based phenolic, flint glass, or cereated glass.

10. The solar cell unit of claim 1, wherein the substrate is tubular shaped and a fluid is passed through said substrate.

11. The solar cell unit of claim 10, wherein the fluid is water, air, nitrogen, or helium.

12. The solar cell unit of claim 1, wherein the substrate has a hollow core.

13. The solar cell unit of claim 1, wherein the back-electrode is made of aluminum, molybdenum, tungsten, vanadium, rhodium, niobium, chromium, tantalum, titanium, steel, nickel, platinum, silver, gold, an alloy thereof, or any combination thereof.

14. The solar cell unit of claim 1, wherein the back-electrode is made of indium tin oxide, titanium nitride, tin oxide, fluorine doped tin oxide, doped zinc oxide, aluminum doped zinc oxide, gallium doped zinc oxide, boron dope zinc oxide indium-zinc oxide, a metal-carbon black-filled oxide, a graphite-carbon black-filled oxide, a carbon black-carbon black-filled oxide, a superconductive carbon black-filled oxide, an epoxy, a conductive glass, or a conductive plastic.

15. The solar cell unit of claim 1, wherein the semiconductor junction comprises a homojunction, a heterojunction, a heteroface junction, a buried homojunction, a p-i-n junction, or a tandem junction.

16. The solar cell unit of claim 1, wherein the transparent conductive layer comprises carbon nanotubes, tin oxide, fluorine doped tin oxide, indium-tin oxide (ITO), doped zinc oxide, aluminum doped zinc oxide, gallium doped zinc oxide, boron dope zinc oxide indium-zinc oxide or any combination thereof.

17. The solar cell unit of claim 1, wherein said semiconductor junction comprises an absorber layer and a junction partner layer, wherein said junction partner layer is circumferentially disposed on said absorber layer.

18. The solar cell unit of claim 17, wherein said absorber layer is copper-indium-gallium-diselenide and said junction partner layer is In₂Se₃, In₂S₃, ZnS, ZnSe, CdInS, CdZnS, ZnIn₂Se₄, Zn_1-xMg_xO, CdS, SnO₂, ZnO, ZrO₂, or doped ZnO.

19. The solar cell unit of claim 17, wherein said absorber layer is between 0.5 μ

m and 2.0 μ

m thick.

20. The solar cell unit of claim 17, wherein a composition ratio of Cu/(In+Ga) in said absorber layer is between 0.7 and 0.95.

21. The solar cell unit of claim 17, wherein a composition ratio of Ga/(In+Ga) in said absorber layer is between 0.2 and 0.4.

22. The solar cell unit of claim 17, wherein the absorber layer comprises CIGS having a <

110>

crystallographic orientation.

23. The solar cell unit of claim 17, wherein the absorber layer comprises CIGS having a <

112>

crystallographic orientation.

24. The solar cell unit of claim 17, wherein the absorber layer comprises CIGS that is randomly oriented.

25. The solar cell unit of claim 1, wherein the solar cell further comprises an intrinsic layer circumferentially disposed on said semiconductor junction and wherein the transparent conductive layer is disposed on said intrinsic layer.

26. The solar cell unit of claim 25, wherein the intrinsic layer comprises an undoped transparent oxide.

27. The solar cell unit of claim 25, wherein the intrinsic layer comprises undoped zinc oxide.

28. The solar cell unit of claim 1, further comprising a filler layer circumferentially disposed on said transparent conductive layer, wherein said transparent casing is circumferentially disposed on said filler layer thereby circumferentially sealing said solar cell.

29. The solar cell unit of claim 28, wherein the filler layer comprises ethylene vinyl acetate (EVA), silicone, silicone gel, epoxy, polydimethyl siloxane (PDMS), RTV silicone rubber, polyvinyl butyral (PVB), thermoplastic polyurethane (TPU), a polycarbonate, an acrylic, a fluoropolymer, or a urethane.

30. The solar cell unit of claim 28, wherein the filler layer has a viscosity of less than 1×

10⁶ cP.

31. The solar cell unit of claim 28, wherein the filler layer has a thermal coefficient of expansion of greater than 500×

10<sup>−

6</sup>/°

C.

32. The solar cell unit of claim 28, wherein the filler layer is formed from silicon oil mixed with a dielectric gel.

33. The solar cell unit of claim 28, wherein the silicon oil is a polydimethylsiloxane polymer liquid and the dielectric gel is a mixture of a first silicone elastomer and a second silicone elastomer.

34. The solar cell unit of claim 28, wherein the filler layer is formed from X %, by weight, a polydimethylsiloxane polymer liquid, Y %, by weight, a first silicone elastomer, and Z %, by weight, a second silicone elastomer, where X, Y, and Z sum to 100.

35. The solar cell unit of claim 34, wherein the polydimethylsiloxane polymer liquid has the chemical formula (CH₃)₃SiO[SiO(CH₃)₂]_nSi(CH₃)₃, where n is a range of integers chosen such that the polymer liquid has an average bulk viscosity that falls in the range between 50 centistokes and 100,000 centistokes.

36. The solar cell unit of claim 34, wherein the first silicone elastomer comprises at least sixty percent, by weight, dimethylvinyl-terminated dimethyl siloxane and between 3 and 7 percent by weight silicate.

37. The solar cell unit of claim 34, wherein the second silicone elastomer comprises:

(i) at least sixty percent, by weight, dimethylvinyl-terminated dimethyl siloxane;

(ii) between ten and thirty percent by weight hydrogen-terminated dimethyl siloxane; and

(iii) between 3 and 7 percent by weight trimethylated silica.

38. The solar cell unit of claim 34 wherein X is between 30 and 90;

Y is between 2 and 20; and

Z is between 2 and 20.

39. The solar cell unit of claim 1, further comprising a water resistant layer circumferentially disposed on said transparent conductive layer, wherein said transparent casing is circumferentially disposed on said water resistant layer thereby circumferentially sealing said solar cell.

40. The solar cell unit of claim 39, wherein the water resistant layer comprises clear silicone, SiN, SiO_xN_y, SiO_x, or Al₂O₃, where x and y are integers.

41. The solar cell unit of claim 1, further comprising:

a water resistant layer circumferentially disposed on said transparent conductive layer; and

a filler layer circumferentially disposed on said water resistant layer, wherein said transparent casing is circumferentially disposed on said filler layer thereby circumferentially sealing said solar cell.

42. The solar cell unit of claim 1, further comprising:

a filler layer circumferentially disposed on said transparent conductive layer; and

a water resistant layer circumferentially disposed on said water resistant layer, wherein said transparent casing is circumferentially disposed on said water resistant layer thereby circumferentially sealing said solar cell.

43. The solar cell unit of claim 1, further comprising an antireflective coating circumferentially disposed on said transparent casing.

44. The solar cell unit of claim 43, wherein the antireflective coating comprises MgF₂, silicon nitrate, titanium nitrate, silicon monoxide, or silicon oxide nitrite.

45. The solar cell unit of claim 1, wherein said solar cell is cylindrical shaped and has a cylindrical axis, and wherein said solar cell further comprises at least one electrode strip, wherein each electrode strip in the at least one electrode strip is overlayed on the transparent conductive layer along the cylindrical axis of the solar cell.

46. The solar cell unit of claim 45, wherein the at least one electrode strip comprises a plurality of electrode strips that are positioned at spaced intervals on the transparent conductive layer such that the plurality of electrode strips run parallel or approximately parallel to each other along the cylindrical axis of the solar cell.

47. The solar cell unit of claim 46, wherein electrode strips in the plurality of electrode strips are spaced out at even intervals on a surface of the transparent conductive layer.

48. The solar cell unit of claim 46, wherein electrode strips in the plurality of electrode strips are spaced out at uneven intervals on a surface of the transparent conductive layer.

49. The solar cell unit of claim 1, wherein said substrate has a Young'"'"'s modulus of 20 GPa or greater.

50. The solar cell unit of claim 1, wherein said substrate has a Young'"'"'s modulus of 40 GPa or greater.

51. The solar cell unit of claim 1, wherein said substrate has a Young'"'"'s modulus of 70 GPa or greater.

52. The solar cell unit of claim 1, wherein said substrate is made of a linear material.

53. The solar cell unit of claim 1, wherein all or a portion of the substrate is a rigid tube or a rigid solid rod.

54. The solar cell unit of claim 1, wherein all or a portion of the substrate is characterized by a circular cross-section, an ovoid cross-section, a triangular cross-section, a pentangular cross-section, a hexagonal cross-section, a cross-section having at least one arcuate portion, or a cross-section having at least one curved portion.

55. The solar cell unit of claim 1, wherein a first portion of the substrate is characterized by a first cross-sectional shape and a second portion of the substrate is characterized by a second cross-sectional shape.

56. The solar cell unit of claim 55, wherein the first cross-sectional shape and the second cross-sectional shape are the same.

57. The solar cell unit of claim 55, wherein the first cross-sectional shape and the second cross-sectional shape are different.

58. The solar cell unit of claim 55, wherein at least ninety percent of the length of the substrate is characterized by the first cross-sectional shape.

59. The solar cell unit of claim 55, wherein the first cross-sectional shape is planar and the second cross-sectional shape has at least one arcuate side.

60. The solar cell unit of claim 1, wherein a cross-section of the substrate is circumferential and has an outer diameter of between 1 mm and 1000 mm.

61. The solar cell unit of claim 1, wherein a cross-section of the substrate is circumferential and has an outer diameter of between 14 mm and 17 mm.

62. The solar cell unit of claim 1, wherein a cross-section of the substrate is characterized by

an inner radius defining a hollowed interior of the substrate, and

an outer radius defining a perimeter of the substrate.

63. The solar cell unit of claim 62 wherein the thickness of the substrate is between 0.1 mm and 20 mm.

64. The solar cell unit of claim 62, wherein the thickness of the substrate is between 1 mm and 2 mm.

65. The solar cell unit of claim 1, wherein the solar cell unit has a length that is between 5 mm and 10,000 mm.

66. A solar cell assembly comprising a plurality of solar cell units, each solar cell unit in the plurality of solar cell units having the structure of the solar cell unit of claim 1, wherein solar cell units in said plurality of solar cell units are arranged in coplanar rows to form said solar cell assembly.

67. The solar cell assembly of claim 66, further comprising an albedo surface positioned to reflect sunlight into the plurality of solar cell units.

68. The solar cell assembly of claim 67, wherein the albedo surface has an albedo that exceeds 80%.

69. The solar cell assembly of claim 67, wherein the albedo surface is Lambertian or diffuse.

70. The solar cell assembly of claim 66, wherein a first solar cell unit and a second solar cell unit in the plurality of solar cell units is electrically arranged in series.

71. The solar cell assembly of claim 66, wherein a first solar cell unit and a second solar cell unit in the plurality of solar cell units is electrically arranged in parallel.

72. The solar cell unit of claim 1, wherein an outer surface of the transparent casing is textured.

73. A solar cell assembly comprising:

a plurality of solar cell units, each solar cell unit in the plurality of solar cell units having the structure of the solar cell unit of claim 1;

and

a plurality of internal reflectors, wherein

the plurality of solar cell units and the plurality of internal reflectors are arranged in coplanar rows in which internal reflectors in the plurality of solar cell units abut solar cell units in the plurality of solar cell units thereby forming the solar cell assembly.

74. The solar cell assembly of claim 73, wherein an internal reflector in said plurality of internal reflectors has a hollow core.

75. The solar cell assembly of claim 73, 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.

76. The solar cell assembly of claim 75, wherein the layer of reflective material is polished aluminum, aluminum alloy, silver, nickel or steel.

77. The solar cell assembly of claim 73, wherein an internal reflector in said plurality of internal reflectors is a single piece made out of a reflective material.

78. The solar cell assembly of claim 77, wherein the reflective material is polished aluminum, aluminum alloy, silver, nickel or steel.

79. The solar cell assembly of claim 73, wherein an internal reflector in said plurality of internal reflectors comprises a plastic casing onto which is layered a metal foil tape.

80. The solar cell assembly of claim 79, wherein the metal foil tape is aluminum foil tape.

81. The solar cell assembly of claim 73, wherein a cross-sectional shape of an internal reflector in said plurality of internal reflectors is asteroid or involute.

82. The solar cell assembly of claim 73, 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, parabolic, concave, circular or elliptical.

83. The solar cell assembly of claim 73, 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.

84. The solar cell assembly of claim 73, wherein a first solar cell unit and a second solar cell unit in the plurality of solar cell units is electrically arranged in series.

85. The solar cell assembly of claim 73, wherein a first solar cell unit and a second solar cell unit in the plurality of solar cell units is electrically arranged in parallel.

86. The solar cell unit of claim 1, wherein said solar cell is monolithically integrated.

105. The solar cell unit of claim 1, wherein the solar cell has a cylindrical shape, and wherein

106. The solar cell unit of claim 1, wherein the transparent casing comprises a plurality of transparent casing layers including a first transparent casing layer and a second transparent casing layer, and wherein the first transparent casing layer is circumferentially disposed on said semiconductor junction and the second transparent casing layer is circumferentially disposed on said first transparent casing layer.

107. The solar cell unit of claim 1, wherein the transparent conductive layer is coated with a fluorescent material.

108. The solar cell unit of claim 1, wherein a luminal or an exterior surface of said transparent casing is coated with a fluorescent material.

109. The solar cell unit of claim 41, wherein the water resistant layer or the filler layer is coated with a fluorescent material.

110. The solar cell unit of claim 1, wherein the substrate is a plastic rod.

111. The solar cell unit of claim 1, wherein the substrate is a glass rod.

112. The solar cell unit of claim 1, wherein the substrate is a glass tube.

113. The solar cell unit of claim 1, wherein the substrate is a plastic tube.

87. A solar cell unit comprising:

(A) a solar cell comprising;

a substrate, wherein at least a portion of said substrate is rigid and nonplanar;

a back-electrode circumferentially disposed on said substrate;

a semiconductor junction circumferentially disposed on said back-electrode; and

a transparent conductive layer circumferentially disposed on said semiconductor junction;

(B) a filler layer circumferentially disposed on said transparent conductive layer; and

(C) a transparent casing circumferentially disposed onto said filler layer.

88. The solar cell unit of claim 87, wherein said substrate has a hollow core.

89. The solar cell unit of claim 87, wherein the substrate is made of plastic, metal or glass.

90. The solar cell unit of claim 87, wherein the substrate comprises aluminosilicate glass, borosilicate glass, dichroic glass, germanium/semiconductor glass, glass ceramic, silicate/fused silica glass, soda lime glass, quartz glass, chalcogenide/sulphide glass, fluoride glass, a glass-based phenolic, flint glass, or cereated glass.

91. The solar cell unit of claim 87, wherein said semiconductor junction comprises an absorber layer and a junction partner layer, wherein

said junction partner layer is circumferentially disposed on said absorber layer;

and

said absorber layer is circumferentially disposed on said back-electrode.

92. The solar cell unit of claim 91, wherein said absorber layer is copper-indium-gallium-diselenide and said junction partner layer is CdS, SnO₂, ZnO, ZrO₂, or doped ZnO.

93. The solar cell unit of claim 91, wherein the absorber layer comprises CIGS having a <

110>

crystallographic orientation a <

112>

crystallographic orientation, or no crystallographic orientation.

94. The solar cell unit of claim 87, wherein said solar cell unit further comprises:

(D) an antireflective coating circumferentially disposed on said transparent casing.

95. The solar cell unit of claim 94, wherein the antireflective coating comprises MgF₂, silicon nitrate, titanium nitrate, silicon monoxide, or silicon oxide nitrite.

96. The solar cell unit of claim 87, wherein the solar cell is cylindrical shaped and wherein

97. The solar cell unit of claim 87, wherein the transparent casing comprises a plurality of transparent casing layers including a first transparent casing layer and a second transparent casing layer, and wherein the first transparent casing layer is circumferentially disposed on said filler layer and the second transparent casing layer is circumferentially disposed on said first transparent casing layer.

98. A solar cell unit comprising:

(A) a solar cell comprising;

a substrate, wherein at least a portion of said substrate is rigid and nonplanar;

a back-electrode circumferentially disposed on the substrate;

a semiconductor junction circumferentially disposed on the back-electrode; and

a transparent conductive layer circumferentially disposed on the semiconductor junction;

(B) a water resistant layer circumferentially disposed on the transparent conductive layer;

(C) a filler layer circumferentially disposed on the water resistant layer; and

(D) a transparent casing circumferentially disposed on the filler layer.

99. The solar cell unit of claim 98, wherein said substrate is a tube.

100. The solar cell unit of claim 98, wherein the solar cell has a cylindrical shape and wherein

101. The solar cell unit of claim 98, wherein the transparent casing comprises a plurality of transparent casing layers including a first transparent casing layer and a second transparent casing layer, and wherein the first transparent casing layer is circumferentially disposed on said filler layer and the second transparent casing layer is circumferentially disposed on said first transparent casing layer.

102. A solar cell unit comprising:

(A) a solar cell comprising;

a substrate, wherein at least a portion of said substrate is is rigid and nonplanar;

a back-electrode circumferentially disposed on said substrate;

a semiconductor junction circumferentially disposed on said back-electrode; and

a transparent conductive layer circumferentially disposed on said semiconductor junction;

(B) a filler layer circumferentially disposed on said transparent conductive layer; and

(C) a water resistant layer circumferentially disposed on said filler layer; and

(D) a transparent casing circumferentially disposed onto said water resistant layer.

103. The solar cell unit of claim 102, wherein the solar cell has a cylindrical shape

104. The solar cell unit of claim 102, wherein said substrate is a tube.