WO2006122376A1 - Flexible photovoltaic panel of elongated semiconductor strips - Google Patents

Flexible photovoltaic panel of elongated semiconductor strips Download PDF

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Publication number
WO2006122376A1
WO2006122376A1 PCT/AU2006/000678 AU2006000678W WO2006122376A1 WO 2006122376 A1 WO2006122376 A1 WO 2006122376A1 AU 2006000678 W AU2006000678 W AU 2006000678W WO 2006122376 A1 WO2006122376 A1 WO 2006122376A1
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WO
WIPO (PCT)
Prior art keywords
film layer
film
semiconductor strips
elongated semiconductor
flexible
Prior art date
Application number
PCT/AU2006/000678
Other languages
French (fr)
Inventor
Mark John Kerr
Michael William Spinks
Patrick Joseph Mccaffrey
Anthony Paul Snape
Original Assignee
Origin Energy Solar Pty Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AU2005902606A external-priority patent/AU2005902606A0/en
Application filed by Origin Energy Solar Pty Ltd filed Critical Origin Energy Solar Pty Ltd
Publication of WO2006122376A1 publication Critical patent/WO2006122376A1/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/042—PV modules or arrays of single PV cells
    • H01L31/048—Encapsulation of modules
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/042—PV modules or arrays of single PV cells
    • H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
    • H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1876—Particular processes or apparatus for batch treatment of the devices
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates generally to semiconductor processing, and in particular, to assembling semiconductor devices.
  • the photovoltaic solar cell industry is highly cost sensitive in terms of the efficiency of the power produced by a solar cell and the cost of producing the solar cell. As only a low percentage of the total thickness of a solar cell is used to generate power, minimising the thickness of the solar cell and yielding more solar cells from a piece of silicon are increasingly important.
  • U.S. Patent No. 4,173,820 issued on 13 November 1979 to Mueller et al describes a method of forming a flexible solar array strip using solar cells and a roll of Kapton polymide tape (pre-formed with printed circuits) as a flexible substrate, which is stored on a supply drum. Solder pads are deposited on the printed circuitry of the flexible Kapton substrate. The substrate is withdrawn from the drum and incrementally advanced along a linear path. A spring-loaded cassette stores the solderless solar cells. The cassette and an elevator feed solar cells upwardly into engagement with the pads on the lower layer of the substrate. The pads are heated using an infra-red reflow soldering lamp and then set to attach the solar cells to the printed circuitry.
  • the substrate is advanced, and a spray applicator sprays under pressure a flux solvent to remove excess flux from the solar cells.
  • the solar cells fixed to the flexible substrate are then tested for electrical performance.
  • the solar cells are then encapsulated in an epoxy resin.
  • the encapsulated solar cells are again tested electrically, and any defective solar cells are marked for subsequent removal.
  • the resulting flexible solar array strip is helically wound on a takeup drum.
  • a flexible sliver panel could be used in many applications where the flexible nature is required such as solar power cars, planes, blimps, solar lighting towers and many other applications.
  • a flexible photovoltaic panel comprising: a plurality of photovoltaic cells, the photovoltaic cells comprising a plurality of elongated semiconductor strips configured in a parallel manner and being interconnected between adjacent strips by conductive portions, the elongate strips formed from a semiconductor wafer and each having a width at least substantially equal to the thickness of the wafer and a thickness less than the width of an elongate strip; a plurality of conductive rails, tabs or busbars coupled to the interconnected elongated semiconductor strips; and a flexible film in which the elongated semiconductor strips and the plurality of conductive rails, tabs or busbars are embedded, the flexible film comprising a film layer and the elongated semiconductor strips being adhered to the film layer.
  • the flexible film may be transparent or translucent. Alternatively, the flexible film may be at least partially opaque.
  • the flexible film may be a laminate of films.
  • the wafer may be single crystal silicon or multi-crystalline
  • the plurality of elongated semiconductor strips may be configured as a plurality of banks, each bank comprising a predefined number of elongated semiconductor strips, the elongated semiconductor strips being interconnected sequentially within a bank, and the banks being interconnected by the conductive rails, tabs or busbars.
  • the panel may be conformable.
  • the conductive rails, tabs or busbars may be connected to the film layer.
  • the elongated semiconductor strips may be adhered to the film layer using an optical adhesive, an epoxy, a curable resin, or without adhesive and by virtue of adhesion resulting from the conductive portions.
  • the film layer may comprise fluoropolymer film (ETFE), polyvinyl fluoride (PVF and PVDF), polycarbonate (PC), fiberglass, polyester, polyethylene terephtalate (PET), metals, silicones, or other laminating media as well as multilayer films including PVDF/PET.
  • the film layer may be transparent or translucent.
  • the film layer may comprise reflector spheres.
  • the flexible laminate of films may further comprise an opaque film layer connected to the opposite surface of the film layer relative to the surface to which the elongated semiconductor strips are connected.
  • the flexible film may further comprise another film layer encapsulating the elongated semiconductor strips connected to the film layer and the conductive portions.
  • the other film layer may comprise EVA adhesive, a suitable adhesive, an optical adhesive, or a laminating film.
  • the other film layer is transparent or translucent.
  • the flexible film may further comprise still another film layer formed on the other film layer. The still another film layer may be transparent or translucent.
  • a method of providing a flexible photovoltaic panel comprises: configuring a plurality of photovoltaic cells in a parallel manner, the photovoltaic cells comprising a plurality of elongated semiconductor strips, and interconnecting the adjacent strips using conductive portions, the elongate strips formed from a semiconductor wafer and each having a width at least substantially equal to the thickness of the wafer and a thickness less than the width of an elongate strip; interconnecting the elongated semiconductor strips using a plurality of conductive rails, tabs or busbars; and embedding the elongated semiconductor strips and the plurality of conductive rails, tabs or busbars in a flexible film, the flexible film comprising a film layer and the elongated semiconductor strips being adhered to the film layer.
  • the flexible film may be transparent or translucent. Alternatively, the flexible film may be at least partially opaque.
  • the flexible film may be a laminate of films.
  • the wafer may be single crystal silicon or multi-crystalline (or poly-crystalline) silicon.
  • the method may further comprise the step of configuring the plurality of elongated semiconductor strips as a plurality of banks, each bank comprising a predefined number of elongated semiconductor strips, the elongated semiconductor strips being interconnected sequentially within a bank, and the banks being interconnected by the conductive rails or tabs.
  • the panel may be conformable.
  • the method further comprise the step of connecting the conductive rails, tabs or busbars to the film layer.
  • the elongated semiconductor strips may be adhered to the film layer using an optical adhesive, an epoxy, a curable resin, or without adhesive and by virtue of adhesion resulting from the conductive portions.
  • the film layer may comprise fluoropolymer film (ETFE), polyvinyl fluoride (PVF), silicones, or other laminating media.
  • the film layer may be transparent or translucent.
  • the film layer may comprise reflector spheres.
  • the flexible laminate of films may further comprise an opaque film layer connected to the opposite surface of the film layer relative to the surface to which the elongated semiconductor strips are connected.
  • the flexible film may further comprise another film layer encapsulating the elongated semiconductor strips connected to the film layer and the conductive portions.
  • the other film layer may comprise EVA adhesive, another suitable optical adhesive, or a laminating film.
  • the other film layer may be transparent or translucent.
  • the flexible film may further comprise still another film layer formed on the other film layer.
  • the still another film layer may comprise ethylene propylene terpolymer (EPT).
  • EPT ethylene propylene terpolymer
  • the still another film layer is transparent or translucent.
  • FIG. 1 is an image showing a perspective view of a flexible photovoltaic panel of elongated photovoltaic slivers in a transparent film in accordance with an embodiment of the invention
  • Fig. 2 is an image showing a top plan view of the flexible photovoltaic panel of elongated photovoltaic slivers of Fig. 1;
  • Fig. 3 is an image showing a zoomed top plan view of a portion of the flexible photovoltaic panel of Fig. 2;
  • Fig. 4 is an image showing a perspective view of the flexible photovoltaic panel of Fig. 1 being flexed or bent manually;
  • Fig. 5 is an image showing a perspective view of a flexible photovoltaic panel of elongated photovoltaic slivers in a film that is at least partially opaque in accordance with another embodiment of the invention
  • Fig. 6 is an image showing a top plan view of the flexible photovoltaic panel of elongated photovoltaic slivers of Fig. 5;
  • Fig. 7 is an image showing a perspective view of the flexible photovoltaic panel of Fig. 5 being flexed or bent manually;
  • Fig. 8 is a top plan view of a portion of the flexible photovoltaic panel according to the embodiment of Fig. 1;
  • Fig. 9 is a side, cross-sectional view of the flexible photovoltaic panel of Fig. 8;
  • Fig. 1OA is a flow diagram illustrating a method of providing a flexible photovoltaic panel of elongated semiconductor strips;
  • Fig. 1OB is a flow diagram illustrating further details of the method of Fig. 1OA.
  • Fig. 11 is a more detailed flow diagram of the method of providing a flexible photovoltaic panel of Fig. 1OA. DETAILED DESCRIPTION
  • the embodiments of the invention provide a flexible photovoltaic panel of elongated semiconductor strips or slivers, which are preferably photovoltaic solar cells.
  • the slivers are of the type disclosed in the above-noted International (PCT) Application No. PCT/AU2004/000594, which is incorporated herein by reference.
  • Slivers are thin elongate strips that are separated from a wafer of semiconductor material.
  • the wafer is single crystal silicon or multi-crystalline (or poly-crystalline) silicon.
  • the wafer has a substantially planar surface and a thickness dimension at a right angle to the substantially planar surface.
  • the wafer also has one or more frame portions at opposite ends of the semiconductor strips connecting the strips to the wafer.
  • the semiconductor strips each have a width at least substantially equal to the wafer thickness and a thickness dimension of the strip less than the width.
  • a face of at least one of elongated semiconductor strips lengthwise forms an edge of the wafer or is nearest adjacent the edge. While slivers may be formed at substantially right angles to the planar surface of the wafer, this need not be the case. For example, the slivers may be formed (e.g., etched) at an angle different than ninety degrees to form slivers that are wider than the thickness of the wafer.
  • the width of a sliver may be at least substantially equal to the thickness of the wafer. This covers the case where the width is slightly less than the thickness of the wafer, equal to the thickness, or greater than the thickness of the wafer.
  • the embodiments of the invention may be practiced with slivers that are 1 mm wide and approximately 110 mm long, for example.
  • the slivers may be 70 mm or 120 mm in length.
  • the slivers may be used to implement solar cells.
  • the slivers may be separate one from another by gaps of 80 ⁇ m to 100 ⁇ m. While specific dimensions have disclosed for the slivers, it will be appreciated by those skilled in the art that adjustments and variations in dimensions dependent upon the application may be practiced without departing from the scope and spirit of the invention, provided the sliver width is slightly less than the thickness of the wafer, equal to the thickness, or slightly greater than the thickness of the wafer and the thickness of the sliver is substantially less than the thickness of the wafer.
  • Each panel may comprise any number of slivers (e.g., 6, 35, 70, 300 or 1000 slivers) dependent upon the voltage to be produced, or power to be generated (e.g., 10, 40, 100 watts).
  • slivers e.g., 6, 35, 70, 300 or 1000 slivers
  • power to be generated e.g. 10, 40, 100 watts.
  • the panels are described as comprising specific numbers of slivers, by way of example. However, other numbers of slivers may be practiced without departing from the scope and spirit of the invention, dependent upon any of a number of circumstances including the desired output voltage or power to be produced by the panel.
  • Figs. 1 and 2 are images providing perspective and top plan views of a flexible photovoltaic panel 100 of elongated semiconductor strips or slivers in a transparent film in accordance with an embodiment of the invention.
  • Example dimensions are 340 mm by 450 mm by 1 mm.
  • the semiconductor strips or slivers are preferably photovoltaic cells.
  • Fig. 3 provides a close-up top, plan view of a portion of the flexible photovoltaic panel 100, i.e. sub-assembly or "bank” 110.
  • the panel 100 comprises a number of banks 110 of interconnected semiconductor slivers 130.
  • semiconductor strips, semiconductor slivers, and sliver cells may be used interchangeably.
  • the wafer from which the slivers 130 of semiconductor material are formed may be single crystal silicon or multi-crystalline (or poly-crystalline) silicon, for example.
  • other semiconductor materials may be practiced without departing from the scope and spirit of the invention.
  • a specific configuration for each sliver is given as an example.
  • the slivers may each be about 40 mm to about 200 mm in length, about 0.3 mm to about 2.0 mm in width, and about 10 ⁇ m to about 300 ⁇ m in thickness.
  • the foregoing ranges are provided to illustrate broadly the relative sizes of slivers (or elongated semiconductor strips). The slivers are quite thin.
  • the banks 110 are themselves interconnected by conductive rails or tabs 120, also known as busbars, which are in turn coupled to an interface for connecting the panel 100 to an external circuit or device, typically through a connector of a junction box.
  • the conductive rails, tabs or busbars 120 are used to interconnect banks 110.
  • the conductive rails, tabs, or busbars 120 may comprise strips of conductive metal such as copper (Cu), silver (Ag), copper and tin (Cu+Sn), gold (Au), or the like.
  • Such conductive rails, tabs or busbars 120 are well known to those skilled in the art.
  • the rails, tabs, or busbars 120 can be electrically connected to the sliver cells using the same method and materials that are used for the conductive portions connecting a sliver cell to another sliver cell (e.g., the tabs are another element in the parallel array). Other techniques, such as wire bonding, may be used.
  • the slivers 130 are arranged in a lengthwise parallel manner, with adjacent slivers 130 being interconnected by conductive portions 140.
  • the conductive portions 140 may comprise: conductive metal such as copper (Cu), silver (Ag), copper and tin (Cu+Sn), gold (Au); conductive polymers; conductive plastics; conductive inks; conductive oxides; conductive epoxies; and/or solder.
  • conductive metal such as copper (Cu), silver (Ag), copper and tin (Cu+Sn), gold (Au)
  • conductive polymers such as copper (Cu), silver (Ag), copper and tin (Cu+Sn), gold (Au); conductive polymers; conductive plastics; conductive inks; conductive oxides; conductive epoxies; and/or solder.
  • the foregoing conductive materials are provided by way of example, and other conductive materials may be practiced for the conductive portions 140 without departing from the scope and spirit of the invention.
  • slivers 130 are connected together in such a bank 110.
  • the two outermost slivers 130 in the bank 110 are each coupled to a respective conductive rail, tab or busbar 120.
  • the bank 110 and conductive rails 120 are embedded in film 100, which is flexible.
  • the flexible film 100 is preferably a laminate of films, but this need not be the case provided the film is sufficiently flexible.
  • the laminate of films 150 in one embodiment is transparent, but in other embodiments may be translucent or opaque.
  • a flexible photovoltaic panel 100 configured in this manner is capable of being flexed, as depicted in Fig. 4, where the flexible photovoltaic panel 100 is shown being flexed or bent manually.
  • the bank 110 is shown diagrammatically in Figs. 8 and 9, which are top plan and side, cross-sectional views of the portion of the flexible photovoltaic panel 100, respectively.
  • the elongated semiconductor strips 130 are depicted by elongated black bodies in Fig. 8.
  • White squares 140 represent conductive portions interconnecting the strips or slivers 130, which are embedded in a transparent film 150, which is preferably made up of a number of film layers, as explained hereinafter with reference to Fig. 9.
  • the conductive rails, tabs or busbars 120 are coupled to the two outer strips or slivers 130 and are also embedded in the laminate of films 150.
  • the slivers 130 are disposed on a film 1030.
  • the film 1030 is one layer of the transparent photovoltaic panel 150.
  • the film 1030 may be a fluoropolymer film (ETFE), but other materials may be used.
  • ETFE fluoropolymer film
  • plastics such as polyvinyl fluoride (PVF and PVDF), polycarbonate (PC), fiberglass, polyester, or polyethylene terephtalate (PET) may be practiced as well as multilayer films (including laminates of films) such as PVDF/PET.
  • Transparent fluoropolymer film (ETFE) such as TEFZEL® manufactured by DuPont.
  • transparent polyvinyl fluoride (PVF) such as TEDLAR® manufactured by DuPont may be used.
  • the slivers 130 are preferably adhered to the film 1030 using an adhesive 1040, for example .
  • the slivers 130 may be affixed using an epoxy, a curable resin, or other adhesive technology.
  • the slivers 130 may be fastened or affixed without adhesive or the like but by virtue of adhesion resulting from the conductive interconnection portions 140.
  • the conductive portions 140 may be preprinted on the film 1030 and the slivers may be pressed into the space between the interconnecting conductive portions 140, which firmly hold the sliver 130 in place.
  • solder may be applied to the slivers 130.
  • the slivers 130 are interconnected by the conductive portions 140.
  • the conductive rails, tabs, or busbars 120 are not shown in Fig. 9.
  • EVA 1020 EVA 1020 and another film 1010 which is of the film types described for the film 1030 (eg ETFE, PET etc).
  • Alternative laminating media such as Poly Vinyl Butyl (PVB) and alternative films can be used without departing from the spirit of the invention.
  • An example thickness of the films 1010 and 1030 would be between 0.05 mm and 0.2 mm and an example thickness for the laminating media would be between 0.05 mm and 1.5 mm.
  • Another alternative is that the banks 110 are merely bonded between two films using a simple adhesive, possibly an optical adhesive, with no laminating media.
  • Figs. 5 and 6 are images providing perspective, top plan views of a flexible photovoltaic panel 500 of elongated photovoltaic semiconductor strips or slivers in an at least partially opaque film in accordance with another embodiment of the invention.
  • Fig. 7 shows this opaque panel being flexed.
  • Features of Figs. 1-4 are given corresponding like numbers in Figs. 5-8 (e.g., bank 510 in Fig 5 instead of bank 110 in Fig. 1).
  • bank 510 in Fig 5 instead of bank 110 in Fig. 1
  • the flexible photovoltaic panel of Figures 5, 6 and 7 can be made in the same way as that described above for a transparent flexible photovoltaic panel, except that one of the outer films of the laminate of films (1010 or 1030 in Figure 10A) is replaced with an opaque or coloured film. While a white plastic film is used preferably, it will be appreciated by those skilled in the art that other colours and materials may be practiced for the film 1010 or 1030 including metal layers. Alternatively, one of the films 1010 or 1030 may be coloured by paint or some other method.
  • Fig. 1OA illustrates at a high level a method 1200 of providing a flexible photovoltaic panel of elongated semiconductor strips. Processing commences in step 1210.
  • the elongated semiconductor strips are configured in a parallel manner, and adjacent strips are interconnected using conductive portions.
  • the elongated semiconductor strips are interconnected using conductive rails, tabs or busbars.
  • the elongated semiconductor strips and the conductive rails, tabs or busbars are embedded in a flexible film, which is preferably a laminte of films.
  • Fig. 1OB illustrates a method 1260 of providing a flexible photovoltaic panel. Processing commences in step 1262.
  • photovoltaic cells are configured in a parallel manner.
  • the photovoltaic cells comprise elongated semiconductor strips. Adjacent strips are interconnected using conductive portions.
  • the elongate strips are formed from a semiconductor wafer, and each has a width at least substantially equal to the thickness of the wafer and a thickness less than the width of an elongate strip.
  • the elongated semiconductor strips are interconnected using conductive rails, tabs or busbars.
  • the elongated semiconductor strips and the plurality of conductive rails, tabs or busbars are embedded in a flexible film.
  • the flexible film comprises a film layer and the elongated semiconductor strips being adhered to the film layer. Processing terminates in step 1270.
  • Fig. 11 illustrates in greater detail a process 1300, providing further details of the process 1200 of Fig. 1OA.
  • Processing commences in step 1310.
  • step 1320 the first film of the flexible photovoltaic panel is prepared, and conductive rails, tabs, or busbars are placed on the film.
  • step 1330 the elongated semiconductor strips are configured in a parallel manner.
  • step 1340 the semiconductor strips are bonded to the film using adhesive.
  • step 1350 the semiconductor strips and rails, tabs or busbars are interconnected.
  • step 1360 the assembly of semiconductor strips and rails, tabs, or busbars on the first film is laminated using laminating media and a second film.
  • step 1370 processing terminates.

Abstract

A flexible photovoltaic panel (100, 500) and a method of providing the same are disclosed. The panel (100, 500) comprises a plurality of photovoltaic cells, the photovoltaic cells comprising elongated semiconductor strips (130) configured in a parallel manner and being interconnected between adjacent strips (130) by conductive portions (140) and conductive rails, tabs, or busbars (120, 520) coupled to the interconnected elongated semiconductor strips (130). The elongate strips (130) are formed from a semiconductor wafer, and each has a width at least substantially equal to the thickness of the wafer and a thickness less than the width of an elongate strip (130). Conductive rails, tabs or busbars are coupled to the interconnected elongated semiconductor strips(130). The panel (100, 500) also comprises a film (150, 550) in which the elongated semiconductor strips (130) and the conductive rails, tabs or busbars (120, 520) are embedded. The flexible film (150, 550) comprises a film layer and the elongated semiconductor strips (130) being are to the film layer.

Description

FLEXIBLE PHOTOVOLTAIC PANEL OF ELONGATED SEMICONDUCTOR STRIPS
RELATED APPLICATIONS
The present patent application claims the benefit of an earlier filing date of 20 May 2005 from Australian Provisional Patent Application No. 2005902606 filed in the name of Origin Energy Ltd and entitled "Flexible Photovoltaic Panel of Elongated Semiconductor Strips", which is incorporated herein by reference.
TECHNICAL FIELD
The present invention relates generally to semiconductor processing, and in particular, to assembling semiconductor devices.
BACKGROUND
The photovoltaic solar cell industry is highly cost sensitive in terms of the efficiency of the power produced by a solar cell and the cost of producing the solar cell. As only a low percentage of the total thickness of a solar cell is used to generate power, minimising the thickness of the solar cell and yielding more solar cells from a piece of silicon are increasingly important.
International (PCT) Patent Application No. PCT/AU2004/000594 filed on 07 May 2004 in the name of Origin Energy Solar Pty Ltd et al and entitled "Separating and Assembling Semiconductor Strips" discloses a method for separating elongated strips or sliver cells from a wafer of semiconductor material and assembling them to form "sliver" photovoltaic solar modules. These modules are in principle rigid panels with the rigidity coming from assembling the sliver cells onto a glass panel.
U.S. Patent No. 4,173,820 issued on 13 November 1979 to Mueller et al describes a method of forming a flexible solar array strip using solar cells and a roll of Kapton polymide tape (pre-formed with printed circuits) as a flexible substrate, which is stored on a supply drum. Solder pads are deposited on the printed circuitry of the flexible Kapton substrate. The substrate is withdrawn from the drum and incrementally advanced along a linear path. A spring-loaded cassette stores the solderless solar cells. The cassette and an elevator feed solar cells upwardly into engagement with the pads on the lower layer of the substrate. The pads are heated using an infra-red reflow soldering lamp and then set to attach the solar cells to the printed circuitry. The substrate is advanced, and a spray applicator sprays under pressure a flux solvent to remove excess flux from the solar cells. The solar cells fixed to the flexible substrate are then tested for electrical performance. The solar cells are then encapsulated in an epoxy resin. The encapsulated solar cells are again tested electrically, and any defective solar cells are marked for subsequent removal. The resulting flexible solar array strip is helically wound on a takeup drum. U.S. Patent No. 4,149,665 issued on 17 April 1979 to Costogue et al, which is a continuation-in-part of Mueller et al, describes in greater detail a bonding machine for forming the flexible solar array strip based on the method of Mueller et al.
A need exists for a flexible sliver photovoltaic module that can bend, twist and conform to surfaces. Such a flexible sliver panel could be used in many applications where the flexible nature is required such as solar power cars, planes, blimps, solar lighting towers and many other applications.
SUMMARY In accordance with an aspect of the invention, there is provided a flexible photovoltaic panel. The panel comprises: a plurality of photovoltaic cells, the photovoltaic cells comprising a plurality of elongated semiconductor strips configured in a parallel manner and being interconnected between adjacent strips by conductive portions, the elongate strips formed from a semiconductor wafer and each having a width at least substantially equal to the thickness of the wafer and a thickness less than the width of an elongate strip; a plurality of conductive rails, tabs or busbars coupled to the interconnected elongated semiconductor strips; and a flexible film in which the elongated semiconductor strips and the plurality of conductive rails, tabs or busbars are embedded, the flexible film comprising a film layer and the elongated semiconductor strips being adhered to the film layer. The flexible film may be transparent or translucent. Alternatively, the flexible film may be at least partially opaque. The flexible film may be a laminate of films. The wafer may be single crystal silicon or multi-crystalline (or poly-crystalline) silicon.
The plurality of elongated semiconductor strips may be configured as a plurality of banks, each bank comprising a predefined number of elongated semiconductor strips, the elongated semiconductor strips being interconnected sequentially within a bank, and the banks being interconnected by the conductive rails, tabs or busbars. The panel may be conformable.
The conductive rails, tabs or busbars may be connected to the film layer. The elongated semiconductor strips may be adhered to the film layer using an optical adhesive, an epoxy, a curable resin, or without adhesive and by virtue of adhesion resulting from the conductive portions. The film layer may comprise fluoropolymer film (ETFE), polyvinyl fluoride (PVF and PVDF), polycarbonate (PC), fiberglass, polyester, polyethylene terephtalate (PET), metals, silicones, or other laminating media as well as multilayer films including PVDF/PET. The film layer may be transparent or translucent. The film layer may comprise reflector spheres. The flexible laminate of films may further comprise an opaque film layer connected to the opposite surface of the film layer relative to the surface to which the elongated semiconductor strips are connected. The flexible film may further comprise another film layer encapsulating the elongated semiconductor strips connected to the film layer and the conductive portions. The other film layer may comprise EVA adhesive, a suitable adhesive, an optical adhesive, or a laminating film. The other film layer is transparent or translucent. The flexible film may further comprise still another film layer formed on the other film layer. The still another film layer may be transparent or translucent.
In accordance with an aspect of the invention, there is provided a method of providing a flexible photovoltaic panel. The method comprises: configuring a plurality of photovoltaic cells in a parallel manner, the photovoltaic cells comprising a plurality of elongated semiconductor strips, and interconnecting the adjacent strips using conductive portions, the elongate strips formed from a semiconductor wafer and each having a width at least substantially equal to the thickness of the wafer and a thickness less than the width of an elongate strip; interconnecting the elongated semiconductor strips using a plurality of conductive rails, tabs or busbars; and embedding the elongated semiconductor strips and the plurality of conductive rails, tabs or busbars in a flexible film, the flexible film comprising a film layer and the elongated semiconductor strips being adhered to the film layer.
The flexible film may be transparent or translucent. Alternatively, the flexible film may be at least partially opaque. The flexible film may be a laminate of films.
The wafer may be single crystal silicon or multi-crystalline (or poly-crystalline) silicon.
The method may further comprise the step of configuring the plurality of elongated semiconductor strips as a plurality of banks, each bank comprising a predefined number of elongated semiconductor strips, the elongated semiconductor strips being interconnected sequentially within a bank, and the banks being interconnected by the conductive rails or tabs.
The panel may be conformable.
The method further comprise the step of connecting the conductive rails, tabs or busbars to the film layer.
The elongated semiconductor strips may be adhered to the film layer using an optical adhesive, an epoxy, a curable resin, or without adhesive and by virtue of adhesion resulting from the conductive portions. The film layer may comprise fluoropolymer film (ETFE), polyvinyl fluoride (PVF), silicones, or other laminating media. The film layer may be transparent or translucent. The film layer may comprise reflector spheres. The flexible laminate of films may further comprise an opaque film layer connected to the opposite surface of the film layer relative to the surface to which the elongated semiconductor strips are connected. The flexible film may further comprise another film layer encapsulating the elongated semiconductor strips connected to the film layer and the conductive portions. The other film layer may comprise EVA adhesive, another suitable optical adhesive, or a laminating film. The other film layer may be transparent or translucent. The flexible film may further comprise still another film layer formed on the other film layer. The still another film layer may comprise ethylene propylene terpolymer (EPT). The still another film layer is transparent or translucent. Further aspects of the method are implemented in accordance with the above- noted aspects of the panel. BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the invention are described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is an image showing a perspective view of a flexible photovoltaic panel of elongated photovoltaic slivers in a transparent film in accordance with an embodiment of the invention;
Fig. 2 is an image showing a top plan view of the flexible photovoltaic panel of elongated photovoltaic slivers of Fig. 1; Fig. 3 is an image showing a zoomed top plan view of a portion of the flexible photovoltaic panel of Fig. 2;
Fig. 4 is an image showing a perspective view of the flexible photovoltaic panel of Fig. 1 being flexed or bent manually;
Fig. 5 is an image showing a perspective view of a flexible photovoltaic panel of elongated photovoltaic slivers in a film that is at least partially opaque in accordance with another embodiment of the invention;
Fig. 6 is an image showing a top plan view of the flexible photovoltaic panel of elongated photovoltaic slivers of Fig. 5;
Fig. 7 is an image showing a perspective view of the flexible photovoltaic panel of Fig. 5 being flexed or bent manually;
Fig. 8 is a top plan view of a portion of the flexible photovoltaic panel according to the embodiment of Fig. 1;
Fig. 9 is a side, cross-sectional view of the flexible photovoltaic panel of Fig. 8; Fig. 1OA is a flow diagram illustrating a method of providing a flexible photovoltaic panel of elongated semiconductor strips;
Fig. 1OB is a flow diagram illustrating further details of the method of Fig. 1OA; and
Fig. 11 is a more detailed flow diagram of the method of providing a flexible photovoltaic panel of Fig. 1OA. DETAILED DESCRIPTION
A flexible photovoltaic panel and a method of providing the same are described hereinafter. In the following description, numerous specific details, including semiconductor materials, adhesives, films, conductive materials, semiconductor strip or sliver dimensions, and the like are set forth. However, from this disclosure, it will be apparent to those skilled in the art that modifications and/or substitutions may be made without departing from the scope and spirit of the invention. In other circumstances, specific details may be omitted so as not to obscure the invention.
The embodiments of the invention provide a flexible photovoltaic panel of elongated semiconductor strips or slivers, which are preferably photovoltaic solar cells. The slivers are of the type disclosed in the above-noted International (PCT) Application No. PCT/AU2004/000594, which is incorporated herein by reference. Slivers are thin elongate strips that are separated from a wafer of semiconductor material. Preferably, the wafer is single crystal silicon or multi-crystalline (or poly-crystalline) silicon. However, other semiconductor materials may be practiced without departing from the scope and spirit of the invention. The wafer has a substantially planar surface and a thickness dimension at a right angle to the substantially planar surface. The wafer also has one or more frame portions at opposite ends of the semiconductor strips connecting the strips to the wafer. The semiconductor strips each have a width at least substantially equal to the wafer thickness and a thickness dimension of the strip less than the width. A face of at least one of elongated semiconductor strips lengthwise forms an edge of the wafer or is nearest adjacent the edge. While slivers may be formed at substantially right angles to the planar surface of the wafer, this need not be the case. For example, the slivers may be formed (e.g., etched) at an angle different than ninety degrees to form slivers that are wider than the thickness of the wafer. Thus, the width of a sliver may be at least substantially equal to the thickness of the wafer. This covers the case where the width is slightly less than the thickness of the wafer, equal to the thickness, or greater than the thickness of the wafer.
The embodiments of the invention may be practiced with slivers that are 1 mm wide and approximately 110 mm long, for example. In other embodiments, the slivers may be 70 mm or 120 mm in length. The slivers may be used to implement solar cells. The slivers may be separate one from another by gaps of 80 μm to 100 μm. While specific dimensions have disclosed for the slivers, it will be appreciated by those skilled in the art that adjustments and variations in dimensions dependent upon the application may be practiced without departing from the scope and spirit of the invention, provided the sliver width is slightly less than the thickness of the wafer, equal to the thickness, or slightly greater than the thickness of the wafer and the thickness of the sliver is substantially less than the thickness of the wafer.
Each panel may comprise any number of slivers (e.g., 6, 35, 70, 300 or 1000 slivers) dependent upon the voltage to be produced, or power to be generated (e.g., 10, 40, 100 watts). In the following description, the panels are described as comprising specific numbers of slivers, by way of example. However, other numbers of slivers may be practiced without departing from the scope and spirit of the invention, dependent upon any of a number of circumstances including the desired output voltage or power to be produced by the panel.
I. A Flexible Photovoltaic panel
Figs. 1 and 2 are images providing perspective and top plan views of a flexible photovoltaic panel 100 of elongated semiconductor strips or slivers in a transparent film in accordance with an embodiment of the invention. Example dimensions are 340 mm by 450 mm by 1 mm. The semiconductor strips or slivers are preferably photovoltaic cells. Fig. 3 provides a close-up top, plan view of a portion of the flexible photovoltaic panel 100, i.e. sub-assembly or "bank" 110. The panel 100 comprises a number of banks 110 of interconnected semiconductor slivers 130. The terms semiconductor strips, semiconductor slivers, and sliver cells may be used interchangeably. The wafer from which the slivers 130 of semiconductor material are formed may be single crystal silicon or multi-crystalline (or poly-crystalline) silicon, for example. However, other semiconductor materials may be practiced without departing from the scope and spirit of the invention. For purposes of illustration only, a specific configuration for each sliver is given as an example. The slivers may each be about 40 mm to about 200 mm in length, about 0.3 mm to about 2.0 mm in width, and about 10 μm to about 300 μm in thickness. The foregoing ranges are provided to illustrate broadly the relative sizes of slivers (or elongated semiconductor strips). The slivers are quite thin.
As shown in Figs. 2 and 3, the banks 110 are themselves interconnected by conductive rails or tabs 120, also known as busbars, which are in turn coupled to an interface for connecting the panel 100 to an external circuit or device, typically through a connector of a junction box. The conductive rails, tabs or busbars 120 are used to interconnect banks 110. The conductive rails, tabs, or busbars 120 may comprise strips of conductive metal such as copper (Cu), silver (Ag), copper and tin (Cu+Sn), gold (Au), or the like. Such conductive rails, tabs or busbars 120 are well known to those skilled in the art. The rails, tabs, or busbars 120 can be electrically connected to the sliver cells using the same method and materials that are used for the conductive portions connecting a sliver cell to another sliver cell (e.g., the tabs are another element in the parallel array). Other techniques, such as wire bonding, may be used.
The slivers 130 are arranged in a lengthwise parallel manner, with adjacent slivers 130 being interconnected by conductive portions 140. The conductive portions 140 may comprise: conductive metal such as copper (Cu), silver (Ag), copper and tin (Cu+Sn), gold (Au); conductive polymers; conductive plastics; conductive inks; conductive oxides; conductive epoxies; and/or solder. The foregoing conductive materials are provided by way of example, and other conductive materials may be practiced for the conductive portions 140 without departing from the scope and spirit of the invention.
In this example, thirty-five (35) slivers 130 are connected together in such a bank 110. The two outermost slivers 130 in the bank 110 are each coupled to a respective conductive rail, tab or busbar 120. As can be seen in Figs. 1-3, the bank 110 and conductive rails 120 are embedded in film 100, which is flexible. The flexible film 100 is preferably a laminate of films, but this need not be the case provided the film is sufficiently flexible. The laminate of films 150 in one embodiment is transparent, but in other embodiments may be translucent or opaque. A flexible photovoltaic panel 100 configured in this manner is capable of being flexed, as depicted in Fig. 4, where the flexible photovoltaic panel 100 is shown being flexed or bent manually. This allows the panel to be flexed, so that the panel 100 can be affixed to curved or irregular surfaces, such as poles and other cylindrical or curved bodies, for example. The bank 110 is shown diagrammatically in Figs. 8 and 9, which are top plan and side, cross-sectional views of the portion of the flexible photovoltaic panel 100, respectively. The elongated semiconductor strips 130 are depicted by elongated black bodies in Fig. 8. White squares 140 represent conductive portions interconnecting the strips or slivers 130, which are embedded in a transparent film 150, which is preferably made up of a number of film layers, as explained hereinafter with reference to Fig. 9. The conductive rails, tabs or busbars 120 are coupled to the two outer strips or slivers 130 and are also embedded in the laminate of films 150.
As shown in cross-section in Fig. 9, the slivers 130 are disposed on a film 1030. The film 1030 is one layer of the transparent photovoltaic panel 150. In one embodiment, the film 1030 may be a fluoropolymer film (ETFE), but other materials may be used. For example, instead of ETFE, plastics such as polyvinyl fluoride (PVF and PVDF), polycarbonate (PC), fiberglass, polyester, or polyethylene terephtalate (PET) may be practiced as well as multilayer films (including laminates of films) such as PVDF/PET. Transparent fluoropolymer film (ETFE) such as TEFZEL® manufactured by DuPont. Alternatively, transparent polyvinyl fluoride (PVF) such as TEDLAR® manufactured by DuPont may be used.
The slivers 130 are preferably adhered to the film 1030 using an adhesive 1040, for example . However, the slivers 130 may be affixed using an epoxy, a curable resin, or other adhesive technology. Alternatively, the slivers 130 may be fastened or affixed without adhesive or the like but by virtue of adhesion resulting from the conductive interconnection portions 140. For example, the conductive portions 140 may be preprinted on the film 1030 and the slivers may be pressed into the space between the interconnecting conductive portions 140, which firmly hold the sliver 130 in place. Still further, solder may be applied to the slivers 130.
As shown in Fig. 9, the slivers 130 are interconnected by the conductive portions 140. For ease of illustration to simplify the diagram only, the conductive rails, tabs, or busbars 120 are not shown in Fig. 9. Once the slivers 130 are adhered to the film 1030 and interconnected, the assembly may be encapsulated with a suitable silicone or other potant or may be laminated using a laminating media such as Ethylene Vinyl Acetate
(EVA) 1020 and another film 1010 which is of the film types described for the film 1030 (eg ETFE, PET etc). Alternative laminating media such as Poly Vinyl Butyl (PVB) and alternative films can be used without departing from the spirit of the invention. An example thickness of the films 1010 and 1030 would be between 0.05 mm and 0.2 mm and an example thickness for the laminating media would be between 0.05 mm and 1.5 mm. Another alternative is that the banks 110 are merely bonded between two films using a simple adhesive, possibly an optical adhesive, with no laminating media.
II. Another Flexible Photovoltaic panel
Figs. 5 and 6 are images providing perspective, top plan views of a flexible photovoltaic panel 500 of elongated photovoltaic semiconductor strips or slivers in an at least partially opaque film in accordance with another embodiment of the invention. Fig. 7 shows this opaque panel being flexed. Features of Figs. 1-4 are given corresponding like numbers in Figs. 5-8 (e.g., bank 510 in Fig 5 instead of bank 110 in Fig. 1). For the sake of brevity of the description, such like features are to be understood to have the same function and be made similarly, except where explicitly described to the contrary.
The flexible photovoltaic panel of Figures 5, 6 and 7 can be made in the same way as that described above for a transparent flexible photovoltaic panel, except that one of the outer films of the laminate of films (1010 or 1030 in Figure 10A) is replaced with an opaque or coloured film. While a white plastic film is used preferably, it will be appreciated by those skilled in the art that other colours and materials may be practiced for the film 1010 or 1030 including metal layers. Alternatively, one of the films 1010 or 1030 may be coloured by paint or some other method.
III. A Method of Providing a Flexible Photovoltaic Panel
Fig. 1OA illustrates at a high level a method 1200 of providing a flexible photovoltaic panel of elongated semiconductor strips. Processing commences in step 1210. In step 1220, the elongated semiconductor strips are configured in a parallel manner, and adjacent strips are interconnected using conductive portions. In step 1230, the elongated semiconductor strips are interconnected using conductive rails, tabs or busbars. In step 1240, the elongated semiconductor strips and the conductive rails, tabs or busbars are embedded in a flexible film, which is preferably a laminte of films.
Fig. 1OB illustrates a method 1260 of providing a flexible photovoltaic panel. Processing commences in step 1262. In step 1264, photovoltaic cells are configured in a parallel manner. The photovoltaic cells comprise elongated semiconductor strips. Adjacent strips are interconnected using conductive portions. The elongate strips are formed from a semiconductor wafer, and each has a width at least substantially equal to the thickness of the wafer and a thickness less than the width of an elongate strip. In step 1266, the elongated semiconductor strips are interconnected using conductive rails, tabs or busbars. In step 1268, the elongated semiconductor strips and the plurality of conductive rails, tabs or busbars are embedded in a flexible film. The flexible film comprises a film layer and the elongated semiconductor strips being adhered to the film layer. Processing terminates in step 1270.
Fig. 11 illustrates in greater detail a process 1300, providing further details of the process 1200 of Fig. 1OA. Processing commences in step 1310. In step 1320, the first film of the flexible photovoltaic panel is prepared, and conductive rails, tabs, or busbars are placed on the film. In step 1330, the elongated semiconductor strips are configured in a parallel manner. In step 1340, the semiconductor strips are bonded to the film using adhesive. In step 1350, the semiconductor strips and rails, tabs or busbars are interconnected. In step 1360, the assembly of semiconductor strips and rails, tabs, or busbars on the first film is laminated using laminating media and a second film. In step 1370, processing terminates.
IV. Another Flexible Photovoltaic panel Using a Carrier Film In the above implementations, one of the outer films in the laminate has been used as the carrier film (e.g., film 1030 in Fig 9). An alternative method to construct a flexible photovoltaic panel would be to use another film as the carrier film, construct the array of sliver cells, interconnects and rails, tabs, or busbars on this carrier film, and then laminate the fabricated carrier film (with sliver cells etc) between two additional films using a laminating media on both sides of the fabricated carrier film. In the foregoing manner, a flexible photovoltaic panel and methods of providing the same have been described. While only a small number of embodiments have been disclosed, it will be apparent to those skilled in the art in the light of this disclosure that numerous changes and substitutions may be made without departing from the scope and spirit of the invention.
1270

Claims

CLAIMSWe claim:
1. A flexible photovoltaic panel, comprising: a plurality of photovoltaic cells, said photovoltaic cells comprising a plurality of elongated semiconductor strips configured in a parallel manner and being interconnected between adjacent strips by conductive portions, said elongate strips formed from a semiconductor wafer and each having a width at least substantially equal to the thickness of said wafer and a thickness less than the width of an elongate strip; a plurality of conductive rails, tabs or busbars coupled to said interconnected elongated semiconductor strips; and a flexible film in which said elongated semiconductor strips and said plurality of conductive rails, tabs or busbars are embedded, said flexible film comprising a film layer and said elongated semiconductor strips being adhered to said film layer.
2. The panel according to claim 1, wherein said flexible film is transparent or translucent.
3. The panel according to claim 1, wherein said flexible film is at least partially opaque.
4. The panel according to claim 1, wherein said flexible film is a laminate of films.
5. The panel according to claim 1, wherein said wafer is single crystal silicon or multi-crystalline (or poly-crystalline) silicon.
6. The panel according to claim 1 , wherein said plurality of elongated semiconductor strips are configured as a plurality of banks, each bank comprising a predefined number of elongated semiconductor strips, said elongated semiconductor strips being interconnected sequentially within a bank, and said banks being interconnected by said conductive rails, tabs or busbars.
7. The panel according to any one of claims 1 to 6, wherein said panel is conformable.
8. The panel according to claim 1, wherein said conductive rails, tabs or busbars are connected to said film layer.
9. The panel according to claim 1, wherein said elongated semiconductor strips are adhered to said film layer using an optical adhesive, an epoxy, a curable resin, or without adhesive and by virtue of adhesion resulting from said conductive portions.
10. The panel according to claim 8 or 9, wherein said film layer comprises fluoropolymer film (ETFE), polyvinyl fluoride (PVF and PVDF), polycarbonate (PC), fiberglass, polyester, polyethylene terephtalate (PET), metals, silicones, or other laminating media as well as multilayer films including PVDF/PET.
11. The panel according to any one of claims 8 to 10, wherein said film layer is transparent or translucent.
12. The panel according to any one of claims 8 to 10, wherein said film layer comprises reflector spheres.
13. The panel according to claim 12, wherein said flexible laminate of films further comprises an opaque film layer connected to the opposite surface of said film layer relative to the surface to which said elongated semiconductor strips are connected.
14. The panel according to any one of claims 8 to 13, wherein said flexible film further comprises another film layer encapsulating said elongated semiconductor strips connected to said film layer and said conductive portions.
15. The panel according to claim 14, wherein said other film layer comprises EVA adhesive, a suitable adhesive, an optical adhesive, or a laminating film.
16. The panel according to claim 14 or 15, wherein said other film layer is transparent or translucent.
17. The panel according to any one of claims 14 to 16, wherein said flexible film further comprises still another film layer formed on said other film layer.
18. The panel according to claim 17, wherein said still another film layer is transparent or translucent.
19. A method of providing a flexible photovoltaic panel, comprising: configuring a plurality of photovoltaic cells in a parallel manner, said photovoltaic cells comprising a plurality of elongated semiconductor strips, and interconnecting said adjacent strips using conductive portions, said elongate strips formed from a semiconductor wafer and each having a width at least substantially equal to the thickness of said wafer and a thickness less than the width of an elongate strip; interconnecting said elongated semiconductor strips using a plurality of conductive rails, tabs or busbars; and embedding said elongated semiconductor strips and said plurality of conductive rails, tabs or busbars in a flexible film, said flexible film comprising a film layer and said elongated semiconductor strips being adhered to said film layer.
20. The method according to claim 19, wherein said flexible film is transparent or translucent.
21. The method according to claim 19, wherein said flexible film is at least partially opaque.
22. The method according to claim 19, wherein said wafer is single crystal silicon or multi-crystalline (or poly-crystalline) silicon.
23. The method according to claim 19, wherein said flexible film is a laminate of films.
24. The method according to claim 19, further comprising the step of configuring said plurality of elongated semiconductor strips as a plurality of banks, each bank comprising a predefined number of elongated semiconductor strips, said elongated semiconductor strips being interconnected sequentially within a bank, and said banks being interconnected by said conductive rails or tabs.
25. The method according to any one of claims 19 to 24, wherein said panel is conformable.
26. The method according to claim 19, further comprising the step of connecting said conductive rails, tabs or busbars to said film layer.
27. The method according to claim 19, wherein said elongated semiconductor strips are adhered to said film layer using an optical adhesive, an epoxy, a curable resin, or without adhesive and by virtue of adhesion resulting from said conductive portions.
28. The method according to claim 26 or 27, wherein said film layer comprises fluoropolymer film (ETFE), polyvinyl fluoride (PVF), silicones, or other laminating media.
29. The method according to any one of claims 26 to 28, wherein said film layer is transparent or translucent.
30. The method according to any one of claims 26 to 29, wherein said film layer comprises reflector spheres.
31. The method according to claim 30, wherein said flexible laminate of films further comprises an opaque film layer connected to the opposite surface of said film layer relative to the surface to which said elongated semiconductor strips are connected.
32. The method according to any one of claims 26 to 31 , wherein said flexible film further comprises another film layer encapsulating said elongated semiconductor strips connected to said film layer and said conductive portions.
33. The method according to claim 32, wherein said other film layer comprises
EVA adhesive, another suitable optical adhesive, or a laminating film.
34. The method according to claim 32 or 33, wherein said other film layer is transparent or translucent.
35. The method according to any one of claims 32 to 34, wherein said flexible film further comprises still another film layer formed on said other film layer.
36. The method according to claim 35, wherein said still another film layer comprises ethylene propylene terpolymer (EPT).
37. The method according to claim 35 or 36, wherein said still another film layer is transparent or translucent.
PCT/AU2006/000678 2005-05-20 2006-05-22 Flexible photovoltaic panel of elongated semiconductor strips WO2006122376A1 (en)

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