WO2006123938A1 - Method for interconnection of solar cells - Google Patents

Method for interconnection of solar cells Download PDF

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Publication number
WO2006123938A1
WO2006123938A1 PCT/NO2006/000190 NO2006000190W WO2006123938A1 WO 2006123938 A1 WO2006123938 A1 WO 2006123938A1 NO 2006000190 W NO2006000190 W NO 2006000190W WO 2006123938 A1 WO2006123938 A1 WO 2006123938A1
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WO
WIPO (PCT)
Prior art keywords
solar cell
polarity
insulation
solar cells
cell device
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Application number
PCT/NO2006/000190
Other languages
French (fr)
Inventor
Erik Sauar
Per Andersson
Helge Cato Aamodt
Timothy C. Lommasson
Andreas Bentzen
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Renewable Energy Corporation Asa
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Application filed by Renewable Energy Corporation Asa filed Critical Renewable Energy Corporation Asa
Publication of WO2006123938A1 publication Critical patent/WO2006123938A1/en

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    • 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
    • H01L31/0512—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 made of a particular material or composition of materials
    • 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
    • H01L31/0516—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 specially adapted for interconnection of back-contact solar cells
    • 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

Definitions

  • the present invention relates to a method for interconnection of solar cells. More specifically, the invention relates to interconnecting back-contacted solar cells during module assembly by tabbing and stringing.
  • Photovoltaic (PV) modules are generally manufactured by interconnection of several individual photovoltaic solar cells made from silicon wafers, each solar cell generating a relatively large amount of current delivered at a relatively low voltage typically between 0.5-0.8 Volts.
  • interconnection of the individual cells is generally performed in a way such that the negative terminal of one cell is connected to the positive terminal of another cell, i.e. the individual solar cells are connected in a series connection.
  • Such interconnection is generally achieved by soldering conductive wires, so called tabs, to the terminals of the different solar cells (see International Pat. No. WO 92/22929, J.T. Borenstein et al.).
  • the two polarity terminals are present at different surfaces of the cells, one of the terminals typically being at the back surface and the other terminal typically being at the front, i.e. the light-receiving, surface.
  • the tabs are thus soldered such that the front surface of one solar cell is connected to the back surface of the adjacent solar cell. This results in obscuration of a portion of the light-receiving surface of the solar cells, thus reducing the amount of current generated by the PV module.
  • the tabs are connected alternately between the front and back surfaces of the individual solar cells, a non-negligible spacing between the solar cells are needed to accommodate the tabs, reducing the packing density of the solar cells within the module.
  • the solar cells may incorporate a carrier collecting region on the light- receiving surface, in combination with methods to pass current through or around the substrate to a connection area on the back surface.
  • Current can be passed from a collection grid on the light-receiving surface to the back surface around the edges of the solar cell by incorporation of metallized regions on one or several sides of the cells, often referred to as metallization wrap around (MWA), (see B.T. Cavicchi et al., "Large area wrap around cell development", Proc. 16 th European PVSEC, 1984; W. Joos et al., "Back contact buried contact solar cells with metallization wrap around electrodes", Proc. 28 th IEEE PVSC, 2000).
  • MWA metallization wrap around
  • current can be passed to the back surface through metallized holes (or vias) through the substrate, often referred to as metallization wrap through (MWT) when a current collection grid is present on the light-receiving surface, or emitter wrap through (EWT) when no such collection grid is present,
  • MTT metallization wrap through
  • EWT emitter wrap through
  • connection to the front side grid is in this method achieved by small pins attached to the interconnection media, extending through holes in the individual solar cells. This requires very precise alignment of each solar cell, and may thus complicate the assembly process. To the extent necessary, the teachings of the above-mentioned paper and the above two mentioned patents are incorporated herein by reference thereto.
  • E. Van Kerschaver describes interconnection of individual back-contacted solar cells, where one polarity terminal is connected to a current collecting grid on the light-receiving surface through holes in the substrate, and where the two polarity terminals are accessible at the back surface as two separate and individually insulated regions.
  • Series connection of individual solar cells is then achieved by applying one wide conductive lead, covering both the one polarity terminal of one cell and the other polarity terminal of the adjacent cell.
  • Such interconnection poses strict requirements on the geometry of the contact regions at the back surface. Specifically, the two polarity regions must be accessible for contacting near opposite edges of the back surface.
  • each of the two polarity contact regions needs to be one continuous area, excluding the possibility of contacting solar cells where one of the polarity terminals is accessible as contact points or islands.
  • teachings of that document are incorporated herein by reference thereto.
  • the claimed invention aims to overcome the limitations of the above techniques, by allowing interconnection of back contacted solar cells where both polarity terminals are accessible at the same surface. Specifically, the claimed invention allows such interconnection where one or both of the two polarity terminals are accessible as isolated regions or contact points, without short circuiting the cells, thus not posing particular limitations to the geometrical arrangement of the contacting terminals.
  • the present invention relates to a method for interconnecting solar cells, where each solar cell having first and second polarity terminals accessible at the same surface, comprising connecting conductors between the first polarity terminal(s) of a first solar cell and the second polarity terminal(s) of a second solar cell, wherein the conductors connected to the first polarity terminal of the first solar cell is electrically insulated from the second polarity terminal(s) of the same solar cell by an insulation layer.
  • the present invention also relates to a solar cell device comprising interconnected solar cells, where each solar cell comprises first and second polarity terminals accessible at the same surface, where conductors are connected between the first polarity terminal(s) of a first solar cell and the second polarity terminal(s) of a second solar cell and where the conductors connected to the first polarity terminal of the first solar cell is electrically insulated from the second polarity terminal(s) of the same solar cell by an insulation layer.
  • the present invention achieves a simplified assembly of photovoltaic modules consisting of back-contacted solar cells.
  • the invention allows such back- contacted solar cells to be interconnected using existing manufacturing techniques, thus reducing the investment costs and easing implementation of the invention.
  • Modules manufactured using the methods according to the present invention exhibit increased current generation compared to prior art, and simplified processing compared to other techniques of interconnecting back-contacted solar cells.
  • FIG. 1-a is an illustration of interconnection of individual cells.
  • FIG. 1-b is an illustration of an alternative embodiment of fig. 1-a, in which alternate cells do not need to be rotated.
  • FIG. 1-c illustrates the interconnection conductors with insulation material.
  • FIG. 2-a illustrates one embodiment where an insulation material covers the conductors to be used for interconnection of the individual solar cells.
  • FIG. 2-b illustrates another embodiment where insulation layers in the form of precut sheet is placed on each of the individual solar cells in a suitable geometry.
  • individual solar cells are assumed to be interconnected in a series fashion, i.e. by electrically connecting a first polarity terminal region(s) of a first solar cell to a second polarity terminal region(s) of a second solar cell, both polarity terminal region(s) being accessible at the back side surface of the individual solar cells.
  • the assumption of such interconnection in a series fashion is only intended as one possible interconnection scheme, and the claimed invention is equally suitable for interconnecting such back contacted solar cells by electrically connecting the first polarity terminal of the first solar cell to the same polarity terminal of the second solar cell, i.e. in a parallel interconnection of individual solar cells.
  • FIG. 1-a is an illustration of how individual elements within the claimed invention can be geometrically interconnected.
  • individual back-contacted solar cells 1 having both the first polarity terminal regions 3 and the second polarity terminal regions 4 accessible at the same surface 2 of each solar cell 1.
  • the surface 2 is most preferably the back surface of the solar cells, i.e. the surface not intended to be the primary light-receiving surface.
  • the individual solar cells 1 are preferably aligned in such a fashion that one or more of the first polarity terminal regions 3 of the first solar cell and one or more of the second polarity terminal regions 4 of an adjacent solar cell lies along the same axis in the plane of the surface 2 at which the terminals 3 and 4 are accessible.
  • One or more of the first polarity terminal regions 3 of the first solar cell is then electrically connected to one or more of the second polarity terminal regions 4 of an adjacent solar cell by conductors 5.
  • an insulation material (not shown in the FIG. 1-a) is provided underlying the conductors' 5.
  • Methods to achieve electrical contact between the conductors 5 and the different polarity terminal regions 3 and 4 of the adjacent solar cells 1 include, but are not limited to, hot air soldering, infrared light soldering, local heat probe soldering, and ultrasonic bonding.
  • FIG. 1-b contains an illustration of an alternative interconnection geometry of individual solar cells 1 having both the first polarity terminal regions 3 and the second polarity terminal regions 4 accessible at the same surface 2.
  • the two polarity terminal regions 3 and 4 are oriented in such a fashion that adjacent solar cells do not need to be rotated.
  • One or more of the first polarity terminal regions 3 of the first solar cell is then electrically connected to one or more of the second polarity terminal regions 4 of an adjacent solar cell by conductors 5.
  • an insulating material (not shown in FIG. 1-b) is provided underlying the conductors 5.
  • the polarity terminal regions 3 and 4 are preferably arranged along a straight line parallel to each other, as shown in fig. 1-b.
  • the terminal regions are oriented with an angle ⁇ in relation to the edge of the solar cell.
  • the angle ⁇ is preferably between 5° - 45°, even more preferably between 10° - 25° and most preferably 14° for square solar cells.
  • the preferred angle ⁇ will depend on the shape of the rectangle.
  • FIG. 1-c schematically depicts a cross section of a back contacted solar cell 1 along one axis of terminal regions 3 of the same polarity.
  • the figure shows an interconnecting conductor 5 connecting one or more of the same polarity terminal regions 3 of the first solar cell I 5 where electrical insulation between the conductor 5 and areas of the back side 2 of the solar cell 1 other than the first polarity terminal regions 3 is achieved by an insulation material 6.
  • FIG. 2-a illustrates one embodiment of the claimed invention, in which such electrical insulation is achieved by an insulating material 6 covering the electrical conductor 5 prior to interconnection. Electrical contact between the conductor 5 and the terminal region of interest at the solar cell is then achieved by local removal of the insulation material 5 during interconnection of individual solar cells. Such removal of the insulation material can be achieved by, but is not limited to, melting of the insulation layer between the conductor 5 and the terminal region to which electrical connection is to be made during soldering or bonding. In another embodiment of the invention, the insulation material 6 surrounding the conductor 5 contains pre-made disruptions or openings according to the spacing of the terminal regions to which electrical connection is to be made.
  • FIG. 2-b illustrates yet another embodiment of the invention, in which precut sheets of insulation material 6, containing suitable openings 7 through which electrical connection between the conductors and the terminal regions can be made, are placed over the surface of the solar cells containing the terminal regions prior to interconnection. Note that the geometry of the precut sheets of insulation material 6 according to FIG. 2-b is an illustration only, and any other geometry of the precut sheets is also possible.
  • electrically insulating layers are "placed on the solar cells in the form of precut sheets. Any other method for achieving such locally electrically insulating layers covering parts of the surface of the solar cells at which the two polarity terminals are accessible is to be understood as not limiting the scope of the appended claims.
  • Such methods for placing such an insulation layer on such back- contacted cells include, but are not limited to, screen printing an insulation layer on the one surface of the solar cells.

Abstract

The present invention relates to a solar cell device and a method for interconnecting solar cells. The solar cell device comprises interconnected solar cells, where each solar cell comprises first and second polarity terminals accessible at the same surface. Further, conductors are connected between the first polarity terminal(s) of a first solar cell and the second polarity terminal(s) of a second solar cell. The conductors connected to the first polarity terminal of the first solar cell is electrically insulated from the second polarity terminal(s) of the same solar cell by an insulation layer.

Description

Method for interconnection of solar cells
FIELD OF THE INVENTION
The present invention relates to a method for interconnection of solar cells. More specifically, the invention relates to interconnecting back-contacted solar cells during module assembly by tabbing and stringing.
BACKGROUND OF THE INVENTION
Photovoltaic (PV) modules are generally manufactured by interconnection of several individual photovoltaic solar cells made from silicon wafers, each solar cell generating a relatively large amount of current delivered at a relatively low voltage typically between 0.5-0.8 Volts. In order to increase the voltage delivered by the PV modules to a more suitable level, interconnection of the individual cells is generally performed in a way such that the negative terminal of one cell is connected to the positive terminal of another cell, i.e. the individual solar cells are connected in a series connection. Such interconnection is generally achieved by soldering conductive wires, so called tabs, to the terminals of the different solar cells (see International Pat. No. WO 92/22929, J.T. Borenstein et al.).
In prior art solar cell modules, the two polarity terminals are present at different surfaces of the cells, one of the terminals typically being at the back surface and the other terminal typically being at the front, i.e. the light-receiving, surface. In this geometry, the tabs are thus soldered such that the front surface of one solar cell is connected to the back surface of the adjacent solar cell. This results in obscuration of a portion of the light-receiving surface of the solar cells, thus reducing the amount of current generated by the PV module. Moreover, because the tabs are connected alternately between the front and back surfaces of the individual solar cells, a non-negligible spacing between the solar cells are needed to accommodate the tabs, reducing the packing density of the solar cells within the module.
To reduce the radiation shading obtained in conventional solar cells, several mechanisms have been suggested to make both polarity terminals accessible at the back surface of the solar cells. Roughly, the techniques can be divided in two groups as described in the following.
Firstly, the solar cells may incorporate a carrier collecting region on the light- receiving surface, in combination with methods to pass current through or around the substrate to a connection area on the back surface. Current can be passed from a collection grid on the light-receiving surface to the back surface around the edges of the solar cell by incorporation of metallized regions on one or several sides of the cells, often referred to as metallization wrap around (MWA), (see B.T. Cavicchi et al., "Large area wrap around cell development", Proc. 16th European PVSEC, 1984; W. Joos et al., "Back contact buried contact solar cells with metallization wrap around electrodes", Proc. 28th IEEE PVSC, 2000). Alternatively, current can be passed to the back surface through metallized holes (or vias) through the substrate, often referred to as metallization wrap through (MWT) when a current collection grid is present on the light-receiving surface, or emitter wrap through (EWT) when no such collection grid is present, (see US Pat. No. 3,903,427, GJ. Pack; US Pat. No. 5,468,652, J.M. Gee; US Pat. No. 6,384,317Bl, E. Van Kerschaver et al.; US Pat. No. 2004/0261840A1, R.M. Schmit et al.; International Pat. No. WO 2005/006402A2, R.M. Schmit et al.).
Secondly, there may be no carrier collection region on the light receiving surface, both charge type carriers being collected at current collection contact regions solely at the back surface of the cells (see US Pat. No. 4,395,583, A. Meulenberg; US Pat. No. 4,478,879, CR. Baraona et al.; US Pat. No. 4,838,952, H.G. Dill et al.; US Pat. No. 4,927,770, R.M. Swanson).
Common for solar cells employing contact points or regions for both polarity terminals on the same surface is that interconnection of individual solar cells during module assembly is complicated. One way of achieving such interconnection is described by J.M. Gee et al. in US Pat. No. 5,972,732 and in US Pat. No. 5,951,786. In those mentioned patents, interconnection of back-contacted solar cells is obtained by affixing an array of electrical conductors to one side of a planar member, on top of which the back-contacted solar cells are placed. This method for interconnection, however, requires pre-patterning or pre-placement of conductors on a back sheet prior to lay-out of the solar cells, demanding significant changes to the module manufacturing process. Such "advanced" contacting of individual cells, may prove costly and difficult to introduce in existing manufacturing lines. To the extent necessary, the teachings of those two mentioned patents are incorporated herein by reference thereto.
In J.H. Bultman et al., "Interconnection through vias for improved efficiency and easy module manufacturing of crystalline silicon solar cells", J. Solar Energy Materials & Solar Cells 65, (2001) pp. 339-345, a method for interconnection of solar cells employing vias through the substrates is presented, using thin foils with an interconnection grid underlying the solar cells. The mentioned paper is based on US Pat. No. 3,903,427 by GJ. Pack and US Pat. No 3,903,428 by P.N. DeJong, where metallized pins are used to connect to the ligtψ-receiving surface through holes in the solar cell substrates. Connection to the front side grid is in this method achieved by small pins attached to the interconnection media, extending through holes in the individual solar cells. This requires very precise alignment of each solar cell, and may thus complicate the assembly process. To the extent necessary, the teachings of the above-mentioned paper and the above two mentioned patents are incorporated herein by reference thereto.
In US Pat. No. 6,384,317Bl, E. Van Kerschaver describes interconnection of individual back-contacted solar cells, where one polarity terminal is connected to a current collecting grid on the light-receiving surface through holes in the substrate, and where the two polarity terminals are accessible at the back surface as two separate and individually insulated regions. Series connection of individual solar cells is then achieved by applying one wide conductive lead, covering both the one polarity terminal of one cell and the other polarity terminal of the adjacent cell. Such interconnection poses strict requirements on the geometry of the contact regions at the back surface. Specifically, the two polarity regions must be accessible for contacting near opposite edges of the back surface. Moreover, each of the two polarity contact regions needs to be one continuous area, excluding the possibility of contacting solar cells where one of the polarity terminals is accessible as contact points or islands. To the extent necessary, the teachings of that document are incorporated herein by reference thereto.
The claimed invention aims to overcome the limitations of the above techniques, by allowing interconnection of back contacted solar cells where both polarity terminals are accessible at the same surface. Specifically, the claimed invention allows such interconnection where one or both of the two polarity terminals are accessible as isolated regions or contact points, without short circuiting the cells, thus not posing particular limitations to the geometrical arrangement of the contacting terminals.
SUMMARY OF THE INVENTION
The present invention relates to a method for interconnecting solar cells, where each solar cell having first and second polarity terminals accessible at the same surface, comprising connecting conductors between the first polarity terminal(s) of a first solar cell and the second polarity terminal(s) of a second solar cell, wherein the conductors connected to the first polarity terminal of the first solar cell is electrically insulated from the second polarity terminal(s) of the same solar cell by an insulation layer.
The present invention also relates to a solar cell device comprising interconnected solar cells, where each solar cell comprises first and second polarity terminals accessible at the same surface, where conductors are connected between the first polarity terminal(s) of a first solar cell and the second polarity terminal(s) of a second solar cell and where the conductors connected to the first polarity terminal of the first solar cell is electrically insulated from the second polarity terminal(s) of the same solar cell by an insulation layer.
Preferred embodiments of the invention are defined in the dependent claims. Consequently, the present invention achieves a simplified assembly of photovoltaic modules consisting of back-contacted solar cells. The invention allows such back- contacted solar cells to be interconnected using existing manufacturing techniques, thus reducing the investment costs and easing implementation of the invention. Modules manufactured using the methods according to the present invention exhibit increased current generation compared to prior art, and simplified processing compared to other techniques of interconnecting back-contacted solar cells.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following, different non-limiting embodiments according to the present invention will be described with reference to the enclosed drawings, where:
FIG. 1-a is an illustration of interconnection of individual cells.
FIG. 1-b is an illustration of an alternative embodiment of fig. 1-a, in which alternate cells do not need to be rotated.
FIG. 1-c illustrates the interconnection conductors with insulation material.
FIG. 2-a illustrates one embodiment where an insulation material covers the conductors to be used for interconnection of the individual solar cells.
FIG. 2-b illustrates another embodiment where insulation layers in the form of precut sheet is placed on each of the individual solar cells in a suitable geometry.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will now be described with reference to the drawings.
In the present description of the preferred embodiments of the invention, individual solar cells are assumed to be interconnected in a series fashion, i.e. by electrically connecting a first polarity terminal region(s) of a first solar cell to a second polarity terminal region(s) of a second solar cell, both polarity terminal region(s) being accessible at the back side surface of the individual solar cells. The assumption of such interconnection in a series fashion is only intended as one possible interconnection scheme, and the claimed invention is equally suitable for interconnecting such back contacted solar cells by electrically connecting the first polarity terminal of the first solar cell to the same polarity terminal of the second solar cell, i.e. in a parallel interconnection of individual solar cells.
FIG. 1-a is an illustration of how individual elements within the claimed invention can be geometrically interconnected. Referring to FIG. 1, individual back-contacted solar cells 1 having both the first polarity terminal regions 3 and the second polarity terminal regions 4 accessible at the same surface 2 of each solar cell 1. The surface 2 is most preferably the back surface of the solar cells, i.e. the surface not intended to be the primary light-receiving surface. The individual solar cells 1 are preferably aligned in such a fashion that one or more of the first polarity terminal regions 3 of the first solar cell and one or more of the second polarity terminal regions 4 of an adjacent solar cell lies along the same axis in the plane of the surface 2 at which the terminals 3 and 4 are accessible.
One or more of the first polarity terminal regions 3 of the first solar cell is then electrically connected to one or more of the second polarity terminal regions 4 of an adjacent solar cell by conductors 5. In order to prevent electrical short circuits between the first polarity terminal regions 3 and the second polarity regions 4 of the same solar cell I5 an insulation material (not shown in the FIG. 1-a) is provided underlying the conductors' 5. Methods to achieve electrical contact between the conductors 5 and the different polarity terminal regions 3 and 4 of the adjacent solar cells 1 include, but are not limited to, hot air soldering, infrared light soldering, local heat probe soldering, and ultrasonic bonding.
FIG. 1-b contains an illustration of an alternative interconnection geometry of individual solar cells 1 having both the first polarity terminal regions 3 and the second polarity terminal regions 4 accessible at the same surface 2. The two polarity terminal regions 3 and 4 are oriented in such a fashion that adjacent solar cells do not need to be rotated. One or more of the first polarity terminal regions 3 of the first solar cell is then electrically connected to one or more of the second polarity terminal regions 4 of an adjacent solar cell by conductors 5. As mentioned above, an insulating material (not shown in FIG. 1-b) is provided underlying the conductors 5.
The polarity terminal regions 3 and 4 are preferably arranged along a straight line parallel to each other, as shown in fig. 1-b. The terminal regions are oriented with an angle α in relation to the edge of the solar cell. The angle α is preferably between 5° - 45°, even more preferably between 10° - 25° and most preferably 14° for square solar cells. For rectangular solar cells, the preferred angle α will depend on the shape of the rectangle.
FIG. 1-c schematically depicts a cross section of a back contacted solar cell 1 along one axis of terminal regions 3 of the same polarity. The figure shows an interconnecting conductor 5 connecting one or more of the same polarity terminal regions 3 of the first solar cell I5 where electrical insulation between the conductor 5 and areas of the back side 2 of the solar cell 1 other than the first polarity terminal regions 3 is achieved by an insulation material 6.
FIG. 2-a illustrates one embodiment of the claimed invention, in which such electrical insulation is achieved by an insulating material 6 covering the electrical conductor 5 prior to interconnection. Electrical contact between the conductor 5 and the terminal region of interest at the solar cell is then achieved by local removal of the insulation material 5 during interconnection of individual solar cells. Such removal of the insulation material can be achieved by, but is not limited to, melting of the insulation layer between the conductor 5 and the terminal region to which electrical connection is to be made during soldering or bonding. In another embodiment of the invention, the insulation material 6 surrounding the conductor 5 contains pre-made disruptions or openings according to the spacing of the terminal regions to which electrical connection is to be made.
FIG. 2-b illustrates yet another embodiment of the invention, in which precut sheets of insulation material 6, containing suitable openings 7 through which electrical connection between the conductors and the terminal regions can be made, are placed over the surface of the solar cells containing the terminal regions prior to interconnection. Note that the geometry of the precut sheets of insulation material 6 according to FIG. 2-b is an illustration only, and any other geometry of the precut sheets is also possible.
In the embodiment of the claimed invention as depicted in FIG. 2-b and described above, electrically insulating layers are "placed on the solar cells in the form of precut sheets. Any other method for achieving such locally electrically insulating layers covering parts of the surface of the solar cells at which the two polarity terminals are accessible is to be understood as not limiting the scope of the appended claims. Such methods for placing such an insulation layer on such back- contacted cells include, but are not limited to, screen printing an insulation layer on the one surface of the solar cells.
In the description above, new methods and devices for interconnecting individual solar cells having both polarity terminals accessible at the same surface is provided. The principle of the invention relates equally well to any such back-contacted solar cell with interconnection regions for both polarity terminals at the same surface, regardless of the principle of operation or fabrication process of such solar cells.
While several embodiments of the invention have been described, it is understood that various modifications to the disclosed processes and methods may be made without departing from the underlying spirit of the invention or the scope of the subsequent claims.

Claims

1. A method for interconnecting solar cells, where each solar cell having first and second polarity terminals accessible at the same surface, comprising connecting conductors between the first polarity terminal(s) of a first solar cell and the second polarity terminal(s) of a second solar cell, wherein the conductors connected to the first polarity terminal of the first solar cell is electrically insulated from the second polarity terminal(s) of the same solar cell by an insulation layer.
2. The method of claim 1 wherein the conductor is insulated by a surrounding coating.
3. The method of claim 2 wherein the method further comprises local removal of the insulation coating of the conductor, adapted to the respective polarity terminal of the solar cells.
4. The method of claim 3 wherein the method further comprises local removal of coating during soldering, by melting or burning off the insulation coating.
5. The method of claim 2 wherein the insulated coating comprises pre-made openings for electrical connection to the respective polarity terminals of the solar cells.
6. The method of claim 1 wherein the method further comprises applying the insulation as precut insulation sheets underlying the conductor before connecting the conductor to the polarity terminals.
7. The method of claim 1 wherein the method further comprises applying the insulation as an insulating layer on at least parts of the surface of the solar cells surrounding the polarity terminals.
8. The method of claim 7 wherein the insulation layer is deposited by screen printing.
9. The method of claim 7 wherein the insulating layer is deposited by sputtering techniques.
10. The method of claim 7 wherein the insulating layer is deposited by evaporation techniques.
11. The method of claim 7 wherein the insulating layer is deposited by vapor deposition techniques.
12. Method according to claim 1, where the polarity terminals of the same polarity are oriented along an essentially straight line having an angle α in relation to the edge of the solar cell.
13. Method according to claim 12, where he angle α is preferably between 5 ° - 45°, even more preferably between 10° - 25° and most preferably 14°.
14. Solar cell device comprising interconnected solar cells, where each solar cell comprises first and second polarity terminals accessible at the same surface, where conductors are connected between the first polarity terminal(s) of a first solar cell and the second polarity terminal(s) of a second solar cell and where the conductors connected to the first polarity terminal of the first solar cell is electrically insulated from the second polarity terminal(s) of the same solar cell by an insulation layer.
15. Solar cell device according to claim 14, where the conductor is insulated by a surrounding coating.
16. Solar cell device according to claim 15, where the insulation coating of the conductor is locally removed and adapted to the respective polarity terminal of the solar cells.
17. Solar cell device according to claim 16, where the local removal of coating is made during soldering, by melting or burning off the insulation coating.
18. Solar cell device according to claim 15, where the insulated coating comprises pre-made openings for electrical connection to the respective polarity terminals of the solar cells.
19. Solar cell device according to claim 14, where the insulation is applied as precut insulation sheets underlying the conductor before connecting the conductor to the polarity terminals.
20. Solar cell device according to claim 14, where the insulation is applied as an insulating layer on at least parts of the surface of the solar cells surrounding the polarity terminals.
21. Solar cell device according to claim 20, where the insulation layer is deposited by screen printing.
22. Solar cell device according to claim 20, where the insulating layer is deposited by sputtering techniques.
23. Solar cell device according to claim 20, where the insulating layer is deposited by evaporation techniques.
24. Solar cell device according to claim 20, where the insulating layer is deposited by vapor deposition techniques.
25. Solar cell device according to claim 14, where the polarity terminals of the same polarity are oriented along an essentially straight line having an angle α in relation to the edge of the solar cell.
26. Solar cell device according to claim 25, where the angle α is preferably between 5° - 45°, even more preferably between 10° - 25° and most preferably 14°.
PCT/NO2006/000190 2005-05-19 2006-05-19 Method for interconnection of solar cells WO2006123938A1 (en)

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