Solar cell assembly, solar module and method for manufacturing a solar cell assembly

Abstract

A solar cell module includes: a layered structure containing photovoltaic elements; and an electrode assembly disposed on the surface of the layered structure, the electrode assembly including: a plurality of conductive portions; a plurality of first conductive elements disposed on the surface of the layered structure; and a plurality of second conductive elements inserted between the plurality of conductive portions and the plurality of first conductive elements; wherein the plurality of first conductive elements are configured to form ohmic contacts between the plurality of second conductive elements and the surface of the layered structure, and the plurality of second conductive elements are configured to form ohmic contacts between the plurality of first conductive elements and the plurality of conductive portions.

Description

[Technical Field]

[0001] This disclosure relates to solar cell modules, solar modules, and methods for manufacturing solar cell modules. [Previous Technology]

[0002] A solar module that generates electricity from sunlight comprises an array of photovoltaic cells, each cell containing a semiconductor substrate. The cells are conventionally connected such that current flows through a grid of finger electrodes on the cell surface to a series of wider vertical bus electrodes printed on the front and back of the cell. From the bus electrodes, current flows along a series of copper strips to a junction box, each copper strip being soldered to an individual bus electrode.

[0003] The general goal of solar cell development is to achieve high conversion efficiency, balanced by the need to reduce manufacturing costs. Efforts to achieve this have focused particularly on the electrode connections between the solar cells and the semiconductor substrate in the module. However, despite these developments, there remains a need to improve the contact between the electrodes of solar cells to increase their power conversion efficiency. [Summary of the Invention]

[0004] According to a first aspect, a solar cell module is provided, comprising: a layered structure including photovoltaic elements; and an electrode assembly disposed on a surface (e.g., an outer surface) of the layered structure, the electrode assembly comprising: a plurality of conductive wire portions; a plurality of first conductive elements disposed on the surface of the layered structure; and a plurality of second conductive elements inserted between the plurality of conductive wire portions and the plurality of first conductive elements; wherein the plurality of first conductive elements are configured to form ohmic contacts between the plurality of second conductive elements and the surface of the layered structure, and the plurality of second conductive elements are configured to form ohmic contacts between the plurality of first conductive elements and the plurality of conductive wire portions.

[0005] A plurality of second conductive elements are configured to provide an electrical path between a plurality of first conductive elements and a plurality of wires. Accordingly, the plurality of second conductive elements reduce the contact resistivity of the electrode assembly, thereby increasing the fill factor of the solar cell. In this way, the configuration of the (multiple) conductive elements reduces resistance loss, which would otherwise occur due to poor contact interfaces between the plurality of wires and the plurality of first conductive elements disposed on the surface of the layered structure.

[0006] It will be understood that the terms "conductive" and "insulating," as used herein, are explicitly intended to mean electrically conductive and electrically insulating, respectively. The meaning of these terms will be particularly evident given the technical background of this disclosure (photovoltaic solar cell devices). It will also be understood that the term "ohmic contact" is intended to mean a non-rectifying electrical junction (i.e., a junction between two conductors exhibiting substantially linear current-voltage [IV] characteristics).

[0007] The optional features will now be listed. These features can be applied individually or in any combination with any aspect.

[0008] A plurality of first and second conductive elements may respectively define a plurality of finger electrodes and a plurality of elongated buses, disposed on (e.g., printed on) the surface of a layered structure to define a "solar cell" of the solar module, as will be readily understood by those skilled in the art. In particular, the plurality of elongated buses are disposed on top of the plurality of finger electrodes (e.g., printed on top). In other words, in a particular configuration, the plurality of first and second conductive elements may form a portion of the solar cell. In this particular configuration, the plurality of conductive wire portions may at least partially form an electrode assembly applied to the solar cell. The combination of the solar cell and the electrode assembly may be referred to as a solar cell module.

[0009] It will also be understood that a plurality of first and second conductive elements (together with a plurality of wire portions) are configured to work together to draw charge carriers from the layered structure. Accordingly, these components define an electrode assembly, and when combined with the layered structure, define the solar cell assembly of the present invention. In other words, in a particular configuration, a plurality of first and second conductive elements (together with a plurality of wire portions) may at least partially form an electrode assembly applied to a solar cell. The combination of the solar cell and the electrode assembly may be referred to as a solar cell assembly.

[0010] The layered structure may include a front side (e.g., the very front) and a back side (e.g., the very back). The front side may be opposite to the back side. The electrode assembly may define a back electrode assembly disposed on the back side of the layered structure. The solar cell assembly may further include a front electrode assembly disposed on the front side of the layered structure opposite to the back side.

[0011] A plurality of conductive portions may be disposed in the membrane. The membrane may be configured to be electrically insulating and / or optically transparent. The membrane may be configured to provide adhesion between the layered structure and the conductive portions, such that the conductive portions are properly spaced on the layered structure. In this way, the membrane enables the conductive portions to be properly aligned with the layered structure, particularly relative to the plurality of second conductive elements. The membrane may provide mechanical connection between the conductive portions and the layered structure. In an exemplary configuration, the membrane may not cover all surfaces of the layered structure.

[0012] A plurality of conductive wire portions of the back electrode assembly may define a plurality of first conductive wire portions. The film (e.g., an insulating and / or optically transparent film) may define a first (e.g., back) film (e.g., an insulating and / or optically transparent film).

[0013] The front electrode assembly may include a plurality of second conductive portions. The plurality of second conductive portions may be disposed in a second (e.g., front) film (e.g., an insulating and / or optically transparent film).

[0014] A plurality of second conductive portions may be configured to form ohmic contacts with a plurality of third conductive elements of the front electrode assembly. The plurality of third conductive elements may be inserted between the plurality of second conductive portions of the front electrode assembly and the front surface of the layered structure.

[0015] The back electrode assembly may include a plurality of second conductive elements inserted between a plurality of wire portions and a plurality of first conductive elements. Alternatively, the back electrode assembly may include a plurality of second conductive elements as defined above. In this manner, the back electrode assembly may be constructed with two types of plurality of conductive elements, each inserted between a plurality of first wire portions and the back of the layered structure.

[0016] In contrast, the front electrode assembly may only have a single type of plurality of conductive elements (i.e., a plurality of third conductive elements) inserted between the plurality of second wire portions and the front side of the layered structure. That is to say, in the front electrode assembly, the plurality of second wires may be electrically connected to the front side of the layered structure only through the plurality of third conductive elements, that is, there may be no intermediary element between the plurality of second wires and the front side of the layered structure other than the plurality of third conductive elements.

[0017] On the other hand, in the back electrode assembly, the plurality of first wires may be electrically connected to the back of the layered structure only through the plurality of first and second conductive elements, that is, there may be no intermediary element between the plurality of first wires and the back of the layered structure other than the plurality of first and second conductive elements.

[0018] Accordingly, each conductive element of the plurality of second conductive elements (i.e., the back electrode assembly) may be configured to form an ohmic contact between the conductive elements of the plurality of first conductive elements and individual wire portions of the plurality of first wire portions. In contrast, each wire portion of the plurality of second wire portions (i.e., the front electrode assembly) may be configured to form an ohmic contact directly with the conductive elements of the plurality of third conductive elements.

[0019] Considering the back electrode assembly, the plurality of second conductive elements do not affect the shading of the main light incident on the front side of the layered structure when the solar cell assembly is in use. By providing only the plurality of second conductive elements on the back side of the layered structure (i.e., the surface facing away from the incident light), any shading that the conductive elements may cause is limited.

[0020] The front side of the layered structure may define the surface of the layered structure on which light is incident when the solar cell module is in use. The back side of the layered structure will define the surface of the layered structure opposite to the front side, that is, the back side of the layered structure may not be directly exposed to incident light during use. The solar cell module may be configured such that reflected light is directed toward the back side of the layered structure.

[0021] Each of the plurality of second conductive elements may include an elongated bus. The conductive element / elongated bus may be constructed to extend across the surface of the layered structure, thereby forming an ohmic contact with each of the plurality of first conductive elements disposed thereon. The plurality of second conductive elements / elongated buses are formed of a conductive material such that they allow charge carriers to flow from at least one of the plurality of first conductive elements disposed on the back side of the layered structure to at least one of the plurality of first conductive wire portions. In this way, each of the plurality of second conductive elements / elongated buses may define a current collector for the back electrode assembly.

[0022] It is understood that known solar cells may have "redundancy lines" (known as angled redundancy lines) extending a short distance from the edge of the solar cell and extending in a direction not parallel to the finger electrodes (e.g., perpendicular to them or at approximately 45°). In specific cases, each redundancy line may extend across less than 20% of the surface area (e.g., length or width) of the solar cell, for example less than 10%, 7.5%, or 5% of the surface area (e.g., length or width) of the solar cell.

[0023] These "redundant lines" are arranged on the surface of the solar cell to help align the array of wires spanning the finger electrodes. Accordingly, these "redundant lines" are arranged in the same plane as the finger electrodes so as not to disrupt the contact interface between the wires and the finger electrodes. The electrode assembly according to the invention differs from a solar cell having such "redundant lines" because the conductive elements / elongated buses are inserted between a plurality of first conductive elements and a plurality of wire portions. In this way, the plane in which at least a portion of the conductive elements / elongated buses are arranged is adjacent to, but spatially distinct from, the individual planes occupied by the wire portions and the finger electrodes. Thus, the conductive elements / elongated buses advantageously form an ohmic contact between the finger electrodes and the wire portions of the electrode assembly.

[0024] Each of the plurality of second conductive elements / elongated buses may be constructed to extend substantially across the surface of the layered structure, thus defining an elongated bus of "full length". Specifically, each of the plurality of second conductive elements / elongated buses may be constructed to extend across more than 50% of the surface (e.g., length) of the layered structure, for example, more than 60%, 70%, 80%, 90%, or 95% of the surface (e.g., length) of the layered structure. In this way, the "full length" elongated bus may provide ohmic contact between the conductor portion and each underlying finger electrode.

[0025] Each of the plurality of second conductive elements / elongated buses may be configured with a width, an axial length, and a depth. Each such conductive element / elongated bus may be configured such that its axial length is substantially greater than its width. The width and axial length of the conductive element / elongated bus may be measured in a direction perpendicular to the back plane of the layered structure, and the depth may be measured in a direction perpendicular to the back plane of the layered structure. Each such conductive element / elongated bus may be configured with a depth such that it protrudes / stands upright from the back of the layered structure.

[0026] Each of the plurality of second conductive elements / elongated buses may be configured to extend longitudinally across the back side of the layered structure. These conductive elements / elongated buses may be laterally spaced across the back side to define the longitudinal extension space between the buses. These conductive elements / elongated buses may be parallel or substantially parallel to each other. These conductive elements / buses may be equally or substantially equally spaced laterally. Accordingly, the plurality of second conductive elements / buses may form an array of parallel, laterally spaced (e.g., equally spaced) conductive elements / buses.

[0027] At least one of the plurality of second conductive elements / elongated buses may have a substantially rectangular (e.g., square) cross-section (perpendicular to its axial length). These conductive elements / elongated buses may all contain the same rectangular cross-sectional shape. The cross-section of each such conductive element / elongated bus may be uniform along its axial length.

[0028] At least one or each of the plurality of second conductive elements / elongated buses may be configured with a width that varies along its length. The width of the elongated bus may vary along its length, with its widest portion corresponding to the overlap with the underlying finger electrode. Accordingly, the elongated bus may be configured with a periodically fluctuating width, with the widest portion corresponding to the overlap with the finger electrode and the narrowest portion corresponding to the space between the finger electrodes. In this way, the elongated bus may be configured to maximize the contact area with the finger electrode while minimizing the overall size of the bus, thereby reducing associated material costs.

[0029] In an exemplary configuration, the longitudinal edge of the conductive portion / elongated bus may include a plurality of straight facets. Accordingly, the conductor receiving surface of the conductive portion / elongated bus may define a rhombus. Alternatively, the longitudinal edge of the conductive portion / elongated bus may include a plurality of curved facets. The conductor receiving surface of the conductive portion / elongated bus may define a sector.

[0030] The plurality of second conductive elements / elongated buses may be formed of a conductive material. The conductive material may be formed of a metal / metal alloy material, possibly including at least one of Ag, Al, and Au. These conductive elements / elongated buses of the back electrode assembly may be formed using a printing material. The printing material allows it to be easily deposited onto the back of the layered structure to form the plurality of second conductive elements / elongated buses.

[0031] The printing material may be formed using a printable precursor, such as a conductive paste, which may contain a mixture of metal powder (e.g., Ag, Al, Au powder) and glass frit suspended in a solvent. The printable precursor / conductive paste may be fired or cured to form a plurality of printed second conductive elements / elongated buses.

[0032] Each of the plurality of first conductor portions may be constructed with a width, an axial length, and a depth. The conductor portion may be constructed such that its axial length is substantially greater than its width. The width and axial length of the conductor portion may be measured in a direction perpendicular to the back plane of the layered structure, and the depth may be measured in a direction perpendicular to the back plane of the layered structure.

[0033] Each of the plurality of first conductor portions may be configured to extend longitudinally relative to the back side of the layered structure. The conductor portions may be laterally spaced relative to the back side to define the longitudinal extension space between the conductor portions. The conductor portions may be parallel or substantially parallel to each other. The conductor portions may be equally or substantially equally spaced laterally. Accordingly, the plurality of conductor portions may form an array of parallel, laterally spaced (e.g., equally spaced) conductor portions.

[0034] Two or more of the first conductor portions may be electrically or physically joined to form a single conductive conduit.

[0035] The shape and size of the plurality of first and / or second conductor portions (hereinafter also referred to as conductor portions) may be selected to optimize the photoelectronic properties of the front and / or back electrode assemblies (i.e., their current collection and layered structure shielding characteristics). Each conductor portion may have a circular cross-sectional shape (i.e., its axial length transverse to the conductor portion). Alternatively, the conductor portions may have different transverse cross-sectional shapes, including, for example, rectangles, polygons, and triangles. Alternatively, the conductor portion cross-section may be obround-shaped or irregular.

[0036] Each conductor portion of the plurality of first and / or second conductors may be formed of a conductive metal or metal alloy. Each conductor portion may be at least partially coated with a conductive material having a melting point lower than that of the conductor core. Each conductor may be completely coated in an alloy coating, or at least partially coated on one or more sides facing the layered structure.

[0037] The outer cladding may comprise a metallic alloy formed of at least two or more components. The outer cladding alloy may be at least one of lead-based, tin-based, or bismuth-based alloys. The outer cladding may comprise a two-phase, three-phase, or more complex metallic alloy.

[0038] The conductor portion coating may be formed of a metal alloy, including at least one of Ag, Bi, Cd, Ga, In, Pb, Sn, Ti, etc. The conductor portion coating may also include a conductive material, which is formed of metal or alloy particles embedded in an organic matrix.

[0039] At least one or each of the plurality of first and / or second conductor portions may be disposed on the surface of individual first and second insulating optically transparent films. Alternatively or incidentally, at least one conductor portion may be at least partially disposed within the film. In this manner, at least one conductor portion may be embedded in the film such that the surface of the conductor portion protrudes from the surface of the film. Alternatively, at least one or each conductor portion may be substantially enclosed (e.g., completely enclosed) within its individual film while still forming an electrical contact with the conductive elements / elongated buses that overlap with them.

[0040] The first and / or second film may be formed of a polymeric material and possess high toughness, good insulation properties, optical transparency, thermal stability, and shrinkage resistance. Exemplary polymeric materials may include acetates, epoxy resins, fluoropolymers, polyamide resins, polyurethane, rayon, polyolefins, plastilene, rayonext, polyethylene terephthalate (PET), polyvinyl fluoride film, modified ethylene tetrafluoroethylene, etc. In some specific embodiments, the first and / or second film is composed of a single layer of material; however, in some other specific embodiments, the first and / or second film comprises two or more layers, wherein two or more of these layers may comprise different materials and / or material characteristics.

[0041] The surface of the film facing the conductive portion may be coated with a transparent adhesive. During the fabrication of the solar cell module, the film may be heated to soften the adhesive, allowing the film to adhere to the conductive portion under pressure. In this way, the conductive portion may be at least partially embedded in the adhesive. When handling multiple conductive portions and prior to their placement on a layered structure, the first and / or second film may be configured to provide structural support to the conductive portions.

[0042] When the front electrode assembly and / or the back electrode assembly are assembled with the layered structure, the associated insulating optically transparent film may deform to conform to the shape of the conductive portion sandwiched between the film and the layered structure. In other words, the front side of the film may be substantially flat in the non-conductive regions and ridges / protrusions may be formed on the conductive portions in the conductive regions. In this way, each (e.g., longitudinal) conductive region of the film may have an upwardly convex (e.g., transverse) profile (i.e., a substantially semi-circular profile).

[0043] The first insulating optically transparent film of the back electrode assembly may have a front side (facing the layered structure) and a back side opposite to the front side (facing away from the layered structure). At least one of the plurality of first conductive portions may be disposed on the front side of the first film.

[0044] The second insulating optically transparent film of the front electrode assembly may have a front side (facing away from the layered structure) on which light is incident during use and a back side (facing the layered structure) opposite to the front side. At least one of the plurality of second conductive portions may be disposed on the back side of the second film.

[0045] The layered structure may include length and width. The length of the layered structure may be less than its width. The longitudinal and transverse directions spanning the back of the layered structure may be parallel to the length and width directions of the layered structure, respectively. Therefore, a plurality of second conductive elements / elongated buses and wire portions may be configured to extend across the length of the layered structure and be spaced apart along its width.

[0046] At least one of the plurality of first conductor portions may be configured as an overlapping (e.g., partially or completely) conductive element / elongated bus of an electrode assembly (e.g., a back electrode assembly).

[0047] The plurality of conductor portions of the plurality of first conductor portions may be constructed to form overlapping (e.g., partially or completely) corresponding plurality of second conductive elements / elongated buses.

[0048] Each of the plurality of first conductor portions may be constructed as overlapping (e.g., partially or completely) the corresponding conductive elements of the plurality of second conductive elements / elongated buses. For example, each of the plurality of first conductor portions may be constructed as different conductive elements / elongated buses that at least partially overlap the plurality of second conductive elements / elongated buses.

[0049] The axial length of at least one of the plurality of first conductor portions may be configured to be substantially parallel / axially aligned with the axial length of the (plural of second) conductive elements / elongated busbars over which it overlaps.

[0050] The axial lengths of the plurality of first conductor portions may be constructed to be substantially parallel / axially aligned with the axial lengths of the corresponding plurality of second conductive elements / elongated buses that they overlap.

[0051] The axial length of each of the plurality of first conductor portions may be substantially parallel / axially aligned with the axial length of the plurality of second conductive elements that they overlap / the corresponding conductive elements of the elongated bus.

[0052] The substantial alignment between each overlapping conductive element / elongated bus and individual conductor portions thereby reduces the shading caused by the conductive element / elongated bus and the plurality of first conductor portions.

[0053] The substantial alignment between the plurality of second conductive elements / elongated buses and the plurality of first conductor portions also increases the contact area of ​​the interface between these conductor portions and these conductive elements / elongated buses, thereby reducing the contact resistivity. Therefore, solar cell modules can be configured to maintain similar short-circuit currents (i.e., due to similar shading) while increasing the fill factor by reducing the resistivity at the contact interface.

[0054] According to the exemplary configuration of the back electrode assembly, an array of parallel, laterally spaced first conductor portions may overlap (i.e., be directly stacked) on an array of parallel, laterally spaced second conductive elements / elongated buses.

[0055] When at least one conductive element / elongated bus overlaps and aligns with at least one of the plurality of first conductive portions, the width of the conductive element / elongated bus (e.g., at least a first portion of the width) may be at least equal to the thickness of the conductive portion measured on the surface plane of the layered structure. For example, the conductive element / elongated bus may include a width along its entire length that is at least equal to the thickness of the conductive portion.

[0056] When the conductive element / bus is constructed with a width equal to the thickness of the conductor portion (e.g., at least the second portion of the width and / or at least the first portion of the width), the back electrode assembly does not introduce additional shielding because the conductive element / bus has a width similar to that of the conductor portion.

[0057] The width of the conductive element / elongated bus (e.g., at least a third portion of the width) may be smaller than the thickness (e.g., width) of the conductor portion as measured on the surface plane of the layered structure. For example, the conductive element / elongated bus may include a width along its entire length that is smaller than the thickness of the conductor portion. In particular, the width of the conductive element / elongated bus (e.g., at least a third portion of the width) may be only slightly smaller than the thickness of the conductor portion. For example, the width of the conductive element / elongated bus (e.g., at least a third portion of the width) may be approximately 90% of the conductor portion.

[0058] The outer surface of the bend in the conductor portion means that the width of the maximum contact area with the underlying elongated bus is less than the thickness of the conductor portion. Therefore, the elongated bus can be constructed with a slightly narrower width while still maintaining good ohmic contact, while minimizing the shielding effect on the layered structure. For example, the width of the conductive element / elongated bus (e.g., the width of at least the third portion and / or the entire length) may be less than 0.70 mm. For example, the width of the conductive element / elongated bus (e.g., the width of at least the third portion and / or the entire length) may be less than 0.25 mm.

[0059] In specific configurations, the conductor portion may comprise a substantially flat strip with a width between 0.6 mm and 0.7 mm. In this case, the elongated bus may be constructed with a width 0.1 mm smaller than the strip width to reduce the shading effect of the bus.

[0060] Depending on the exemplary specific configuration, the width of the conductive element / elongated bus may be greater than the thickness (e.g., width) of the wire portion. By constructing each conductive element / elongated bus with a width slightly greater than the wire thickness, good electrical contact is ensured, even in the event of minor misalignment between an individual wire and the bus.

[0061] The conductor portion of the plurality of second conductor portions may be as described above for the plurality of first conductor portions.

[0062] A plurality of first conductor portions and a plurality of second conductor portions may be aligned with each other, with layered structures interposed therebetween.

[0063] The plurality of first conductive elements of the electrode assembly (e.g., the back electrode assembly) may include a plurality of finger electrodes (e.g., a plurality of back finger electrodes) disposed on the back side of the layered structure. The plurality of third conductive elements of the front electrode may include a plurality of finger electrodes (i.e., a plurality of front finger electrodes) disposed on the front side of the layered structure.

[0064] Each of the plurality of front and / or back finger electrodes may be constructed with an axial length substantially greater than its width. The width and axial length of the finger electrode may both be measured in the direction perpendicular to the individual surface plane of the layered structure. The finger electrode may extend laterally parallel to the width direction of the layered structure.

[0065] The finger electrodes in each of the plurality of front and / or back finger electrodes may be spaced apart across individual surfaces to define the lateral extension space between the finger electrodes. The finger electrodes may be spaced apart longitudinally in a direction substantially parallel to the length direction of the layered structure. The plurality of finger electrodes may be substantially parallel to each other. Accordingly, the plurality of back finger electrodes may form an array of parallel, longitudinally spaced (e.g., equally spaced) finger electrodes.

[0066] The axial length of at least one of the plurality of back-side finger electrodes may be substantially misaligned (e.g., substantially non-parallel or substantially perpendicular) with the axial length of at least one of the plurality of second conductive elements / elongated buses overlapping thereon. The axial length of at least one of the plurality of back-side finger electrodes may be substantially misaligned (e.g., substantially non-parallel or substantially perpendicular) with the axial length of at least one of the plurality of first conductive portions.

[0067] Accordingly, if the conductive element / elongated busbar is axially aligned with the overlapping wire portion, the axial length of the associated finger electrode may be axially misaligned with both the wire portion and the conductive element / elongated busbar at the same misalignment angle.

[0068] The axial length of the finger electrode may be substantially perpendicular to the axial length of the overlapping wire portion and / or the conductive element / elongated bus. In this way, the finger electrode can be conveniently configured to optimize charge collection from the back side of the layered structure.

[0069] The front side of the layered structure may contain a different number of finger electrodes than the back side of the layered structure. The number of finger electrodes on the back side may be at least 80 and / or up to 300.

[0070] Generally, the finger electrodes may extend substantially across the length of the layered structure. At least one of the plurality of finger electrodes on the front side of the layered structure may extend only partially across the length of the front side. At least one front finger electrode may extend from the edge of the layered structure to define a shortened front finger electrode. In this way, the front side of the layered structure may have a greater number of finger electrodes at the edges, where there are fewer conductive portions to draw charge from the solar cell. The shortened front finger electrode may be arranged alternately with the "full length" front finger electrode across the width of the layered structure. The shortened front finger electrode reduces the amount of shading in the middle region of the layered structure. The shortened front finger electrode may be referred to as a "redundant line" (known as a parallel redundant line).

[0071] Relatively speaking, each back-side finger electrode may be constructed to extend across the substantial length of the layered structure, thus defining a "full length" of back-side finger electrode. Specifically, each back-side finger electrode may be constructed to extend across more than 50% of the surface (e.g., width) of the layered structure, for example, more than 60%, 70%, 80%, 90%, or 95% of the surface (e.g., width) of the layered structure. The greater length (and number) of the back-side finger electrodes increases charge absorption on the back side of the layered structure where shielding is not an issue.

[0072] According to the exemplary configuration of the solar cell module, an array of multiple conductive elements / elongated buses that are parallel and laterally spaced may be overlapped (i.e. directly stacked) and vertically arranged relative to an array of multiple back finger electrodes.

[0073] The plurality of first conductive elements (e.g., back-side finger electrodes) may be formed of a conductive material (i.e., a first conductive material). As described above, the plurality of second conductive elements / elongated buses may be formed of a conductive material (i.e., a second conductive material) that may be the same as or different from the first conductive elements / elongated buses. The plurality of third conductive elements (e.g., front-side finger electrodes) may be formed of a third conductive material that may be the same as or different from (multiple) first and / or second conductive materials.

[0074] At least one or each of the first, second, and third conductive materials may be printed materials. The printed first and / or third conductive materials are capable of forming finger-shaped electrodes with narrow widths and / or depths (relative to their axial lengths) on individual surfaces of the layered structure. The first and / or third conductive materials may be formed of a metal / metal alloy material that may include at least one of Ag, Al, and Au.

[0075] It will be understood that a plurality of first and second conductor portions may be configured to connect multiple solar cell modules together in a solar module. For example, the plurality of second conductor portions may form a partial foil conductor electrode configuration (e.g., supported by an insulating optically transparent film, as described above), which includes an alloy-coated copper conductor grid directly connected to finger electrodes disposed on the front side of the layered structure. This reduces electrical losses and minimizes the impact of cracking or cell damage on the performance of the solar module. Furthermore, the use of a foil conductor electrode configuration results in a significant reduction in module manufacturing costs and optical losses caused by light shading resulting from the conventional bus electrode configuration on the front side.

[0076] It will be understood that the connection between the finger electrodes and the plurality of wires in this foil wire electrode configuration may be unreliable, which can lead to an increase in the resistivity of the solar cell module and a loss of high fill factor. However, the plurality of conductive elements / elongated buses inserted between the plurality of first wires and the finger electrodes on the back of the solar cell module reduce the resistivity of the back electrode module and thereby increase the fill factor of the solar cell module.

[0077] The layered structure of a solar cell module may include multiple layers or elements, wherein at least one of the multiple layers is formed of a semiconductor material. The photovoltaic element (or layer) may be formed of a silicon wafer, thus defining the semiconductor layered structure of the silicon solar cell.

[0078] According to an exemplary configuration of a solar cell module, the layered structure includes a multilayer semiconductor module, including photovoltaic elements and at least one emitter layer positioned opposite to the photovoltaic elements. The at least one emitter layer may be configured opposite to the photovoltaic elements to form a pn junction. The emitter layer may be electrically connected to a front electrode module or a back electrode module. A first emitter layer may be connected to the front electrode module, and a second emitter layer may be connected to the back electrode module.

[0079] It will be understood that layered structures can be used to define any type of solar cell structure. For example, a layered structure may define a heterojunction solar cell. Alternatively, a layered structure may define a series junction solar cell.

[0080] At least one emitting layer may be configured to face the front side of the layered structure. The front electrode assembly may be positioned on the emitting layer. Accordingly, the emitting layer may be disposed between the front electrode assembly and the photovoltaic element of the layered structure.

[0081] The back field layer may be positioned facing the back of the layered structure, i.e., between the photovoltaic element and the back electrode assembly. The back field may be configured to draw charge carriers from the photovoltaic element during the operation of the solar cell. Accordingly, the back electrode assembly may be positioned on the field layer of the layered structure.

[0082] Photovoltaic elements may be formed of semiconductor materials, such as silicon. The semiconductor material or portions thereof may be positively or negatively doped (i.e., p-type or n-type semiconductors), though not necessarily. The semiconductor material may be undoped (i.e., inherently semiconductor). Silicon used for layered structures may be crystalline silicon (e.g., monocrystalline and polycrystalline silicon) or amorphous silicon.

[0083] A multilayer semiconductor module may include an emitter layer containing p-type material and a back field layer containing n-type material, the emitter layer and the back field layer being disposed on opposite sides of a photovoltaic element containing n-type material. A front electrode assembly may be electrically connected to the emitter layer, and a back electrode assembly may be electrically connected to the back field layer. This configuration may define a heterojunction technology (HJT) type solar cell. Thus, the emitter layer and the back field layer may each be formed of amorphous silicon (a-Si:H), and the photovoltaic element may contain crystalline silicon (c-Si).

[0084] The multilayer semiconductor component may include at least one intrinsic layer, i.e., a semiconductor containing intrinsic doping. The at least one intrinsic layer may be disposed between the emitter layer and the photovoltaic element to form a front passivation layer. Alternatively or incidentally, the at least one intrinsic layer may be disposed between the photovoltaic element and the back field layer to form a back passivation layer. The at least one intrinsic layer may be formed of amorphous silicon.

[0085] When the semiconductor material is n-type, it may be constructed with impurities containing group V elements, such as phosphorus (P), arsenic (As), and antimony (Sb). When the semiconductor material is p-type, it may contain impurities containing group III elements, such as boron (B), gallium (Ga), and indium (In). Alternatively, the semiconductor material may be formed from a material that is not silicon.

[0086] The emitting layer formed in the layered structure may define the impurity region of the photovoltaic element that is the opposite of the first conductivity type (e.g., n-type) to the second conductivity type (e.g., p-type), thus forming a pn junction together with the photovoltaic element.

[0087] The interface formed between the p-type and n-type materials at the pn junction allows excess electrons and holes to diffuse into the n-type and p-type materials, respectively. This relative movement of charge carriers results in the formation of a depletion region (e.g., a space charge region) at the pn junction. Once thermal equilibrium is reached, a built-in potential difference is formed across the depletion region.

[0088] During the operation of a solar cell, the plurality of electron-hole pairs generated by light incident on the substrate are separated into electrons and holes by an electric field generated from the built-in potential difference at the pn junction. The separated electrons then move (e.g., tunnel) to the n-type semiconductor, and the separated holes move to the p-type semiconductor. Therefore, when the photovoltaic element is n-type and the emitter is p-type, the separated holes and electrons move to the emitter and the photovoltaic element, respectively. Accordingly, electrons become the dominant carriers in the photovoltaic element, and holes become the dominant carriers in the emitter.

[0089] Depending on the alternative selective configuration, the emitter may be n-type and the photovoltaic element may be p-type to form a pn junction therebetween. In this example, separate holes and separate electrons move to the photovoltaic element and the emitter, respectively.

[0090] The multiple front surfaces of the layered structure may be textured to form textured surfaces, which correspond to uneven surfaces or have uneven features. In this example, the amount of light incident on the layered structure is increased due to the textured surface of the layered structure, thus improving the efficiency of the solar cell.

[0091] The layered structure may further include an anti-reflective layer or coating disposed on the front and / or back side of the layered structure. Each or every anti-reflective layer may have a single-layer or multi-layer structure. The anti-reflective layer may be formed of silicon nitride (SiNx) and / or silicon oxide (SiOx). Alternatively, the anti-reflective layer may be formed of a transparent conductive oxide (TCO), such as indium tin oxide (ITO), which has been textured to provide an anti-reflective surface. The anti-reflective layer advantageously reduces the reflectivity of light incident on the solar cell and increases the selectivity of a predetermined wavelength band, thereby increasing the efficiency of the solar cell.

[0092] The layered structure may include a transparent conductive oxide coating disposed on the front and / or back sides of the layered structure. The transparent conductive oxide coating may be electrically connected to at least one of the emitting layer, the intrinsic layer, and the photovoltaic element of the layered structure. The transparent conductive oxide coating may be configured to increase lateral carrier transport to finger electrodes disposed on individual surfaces of the layered structure. The transparent conductive oxide coating is particularly advantageous in heterojunction devices that contain layers formed of amorphous silicon and exhibit poor carrier mobility.

[0093] The second aspect provides a solar module comprising a plurality of solar cells according to the first aspect. The plurality of solar cells may be electrically coupled together.

[0094] The first solar cell may be electrically coupled to the second solar cell. Thus, a plurality of wire portions of the electrode assembly of the first solar cell may be electrically coupled to a plurality of wire portions of the electrode assembly of the second solar cell. According to an exemplary configuration, a plurality of second wire portions of the front electrode assembly of the first solar cell may be electrically coupled to a plurality of first wire portions of the back electrode assembly of the second solar cell. Accordingly, the two plurality of wire portions may form an electrical connection between two or more solar cells in the module.

[0095] A plurality of first conductive wire portions of the back electrode assembly of the first solar cell may be physically and / or electrically connected to a plurality of second conductive wire portions of the front electrode assembly of the second solar cell (e.g., integrally formed). In this way, the plurality of conductive wire portions may provide a direct electrical connection between the first and second solar cells, thereby increasing the charge flow between them. Constructing the conductive wire portions in this way eliminates the need for separate connections (e.g., copper strips) between adjacent solar cells, thereby reducing the number and complexity of manufacturing steps required to fabricate a solar module.

[0096] In a specific configuration, a plurality of third conductive elements of the front electrode assembly of the first solar cell are connected to a plurality of first conductive elements of the back electrode assembly of the second solar cell only via a plurality of first and second wire portions and a plurality of second conductive elements.

[0097] The solar module may include a frame to house a plurality of solar cell modules. The frame may include a front panel and a back panel, respectively disposed on the front and back sides of the plurality of solar cell modules. At least one or each of the front panel and the back panel may be formed of glass (e.g., a glass sheet). The solar module may include an encapsulant configured to provide adhesion between the front and back panels and the plurality of solar cell modules. In this manner, the encapsulant may be disposed between the glass sheet of the solar module and an insulating optically transparent film of one of the plurality of solar cell modules. The encapsulant may be configured to prevent moisture from entering the solar module. Accordingly, the encapsulant may be formed of ethylene vinyl acetate (EVA) or any other material suitable for moisture resistance.

[0098] According to a third aspect, a method for manufacturing a solar cell according to the first aspect is provided, comprising: providing a layered structure including photovoltaic elements; and disposing electrode assemblies on the surface of the layered structure, wherein disposing the electrode assemblies comprises: constructing a plurality of first conductive elements on the surface of the layered structure to form ohmic contacts therewith; constructing a plurality of second conductive elements on the plurality of first conductive elements to form ohmic contacts therewith; and disposing a plurality of wire portions on the plurality of second conductive elements to form ohmic contacts therewith. Alternatively, the plurality of wire portions are disposed in a film (e.g., an insulating and / or optically transparent film).

[0099] The layered structure may include a back side (e.g., the rearmost side) and a front side opposite to the back side (e.g., the frontmost side). Accordingly, the method may include configuring an electrode assembly onto the back side of the layered structure to define a back electrode assembly. The method may further include configuring a front electrode assembly onto the front side of the layered structure.

[0100] A plurality of conductive wire portions of the back electrode assembly may define a plurality of first conductive wire portions (e.g., disposed in a first insulating and / or optically transparent film). In this configuration, the method of configuring the front electrode assembly may include constructing a plurality of third conductive elements onto the front side of the layered structure to form ohmic contacts therewith, and configuring a plurality of second conductive wire portions onto the plurality of third conductive elements to form ohmic contacts therewith. The plurality of second conductive wire portions may be disposed in a second film (e.g., an insulating and / or optically transparent film).

[0101] The method of configuring only the back electrode assembly may include constructing a plurality of second conductive elements inserted between a plurality of wire portions and a plurality of first conductive elements. That is, in the method of configuring the front electrode assembly, the plurality of second wires may be connected to the front of the layered structure only through a plurality of third conductive elements, i.e., there may be no intermediary element between the plurality of second wires and the front of the layered structure other than the plurality of third conductive elements. On the other hand, in the method of configuring the back electrode assembly, the plurality of first wires may be connected to the back of the layered structure only through a plurality of first and second conductive elements, i.e., there may be no intermediary element between the plurality of first wires and the back of the layered structure other than the plurality of first and second conductive elements.

[0102] A method for constructing a plurality of third conductive elements on the front side of a layered structure may include depositing (e.g., directly) a plurality of elongated finger electrodes on the front side, i.e., a plurality of front finger electrodes. Similarly, a method for constructing a plurality of first conductive elements on the back side of a layered structure may include depositing (e.g., directly) a plurality of elongated finger electrodes on the back side, i.e., a plurality of back finger electrodes.

[0103] A plurality of second conductive elements may be constructed to define a plurality of elongated buses. The method may include depositing (e.g., directly) at least one conductive element on top of (i.e., overlapping) at least one of the plurality of elongated finger electrodes disposed on the back side.

[0104] A method for depositing a plurality of back-side finger electrodes may include depositing (e.g., directly) a first conductive material onto the back side of the layered structure. A method for depositing a plurality of second conductive elements / elongated buses may include depositing (e.g., directly and indirectly) a second conductive material onto the back side of the layered structure to form a plurality of elongated buses. That is, in areas where back-side finger electrodes appear on the back side, elongated buses may be deposited directly on the back-side finger electrodes, and thus indirectly deposited on the back side; however, in areas where back-side finger electrodes do not appear on the back side, elongated buses may be deposited directly on the back side. A method for depositing a plurality of front-side finger electrodes may include depositing (e.g., directly) a third conductive material onto the front side of the layered structure.

[0105] At least one of the first, second, and third conductive materials may be deposited by various methods, including vapor deposition, plating, printing, etc. For example, the first, second, and third conductive materials may each comprise a first, second, and third printed material.

[0106] The method of depositing the first conductive material may include printing a first printable precursor of the first printing material onto the back side of the layered structure. The method may further include curing the first printable precursor according to a first firing process to form a conductive element / elongated bus.

[0107] The method of depositing the second conductive material may include printing a second printable precursor of the second printing material onto the back side of the layered structure. The method may further include curing the second printable precursor according to a second firing process to form a plurality of back-side finger electrodes.

[0108] The method of depositing a third conductive material may include printing a third printable precursor of a third printing material onto the front side of a layered structure. The method may further include curing the third printable precursor according to a third firing process to form a plurality of front-side finger electrodes.

[0109] A method for curing at least one of (a plurality of) first, second, and third printable precursors may include firing the printable precursor disposed on individual surfaces of a layered structure in a furnace. At least one of (a plurality of) first, second, and third printable precursors may contain a metal paste, which may be obtained by mixing metal powder, glass frit, and a suitable solvent.

[0110] The first printable precursor (and therefore the first conductive material) used to form a plurality of back-side finger electrodes may differ from the second printable precursor used to form conductive elements / buses. Thus, the method may include printing the first printable precursor onto the back side of a layered structure, and then firing the layered structure according to a first firing process to form a plurality of back-side finger electrodes. The method may further include depositing the second printable precursor onto the back side such that it at least partially overlaps at least one elongated back-side finger electrode, and then firing the layered structure according to a second firing process to form a plurality of conductive elements / elongated buses.

[0111] The first, second, and third conductive materials may each / all contain different chemical compositions. The first, second, and third firing processes may each / all contain different firing parameters, such as firing temperature.

[0112] The method may include depositing a plurality of second conductive elements / elongated buses such that the axial length of at least one conductive element may be substantially non-parallel (e.g., substantially perpendicular) to the axial length of the at least one finger electrode it overlaps with. The method may include depositing a plurality of second conductive elements / elongated buses such that they are configured perpendicular to the plurality of back-side finger electrodes.

[0113] The method may include depositing a plurality of second conductive elements / elongated buses at designated locations on the back side of the layered structure, such that they can receive a plurality of first conductor portions, i.e., conductor receiving locations. Each of the (plural) conductor receiving locations may be determined based on the architecture (i.e., lateral spacing) of the conductor portions within the plurality of first conductor portions. In this way, the method ensures that the plurality of second conductive elements are arranged on the back side of the layered structure such that they can be overlapped (e.g., partially or completely) by the plurality of first conductor portions.

[0114] Once a plurality of second conductive elements / elongated buses are deposited onto the finger electrodes disposed on the back side of the layered structure, a plurality of first conductive wire portions may overlap (e.g., partially or completely) onto the corresponding plurality of second conductive elements / elongated buses.

[0115] The method may include constructing at least one of a plurality of first conductor portions to overlap (e.g., partially or completely) the (plural of second) conductive elements / elongated buses of the back electrode assembly.

[0116] The method may include constructing a plurality of first conductor portions to overlap (e.g., partially or completely) corresponding plurality of second conductive elements / elongated buses.

[0117] The method may include constructing each of a plurality of first conductor portions to overlap (e.g., partially or completely) a plurality of second conductive elements / elongated buses with corresponding (e.g., different) conductive elements.

[0118] The method may further include configuring the axial length of at least one of the plurality of first conductor portions to be parallel / axially aligned (or substantially parallel / axially aligned) to the axial length of the (plural of second) conductive elements / elongated buses of the back electrode assembly over which they overlap.

[0119] The method may include constructing a plurality of conductor portions of a plurality of first conductor portions such that their axial lengths are parallel to / axially aligned (or substantially parallel to / axially aligned) with the axial lengths of the corresponding plurality of second conductive elements / elongated buses over which they overlap.

[0120] The method may include constructing each of a plurality of first conductor portions such that their axial lengths are parallel to / axially aligned (or substantially parallel to / axially aligned) with the axial lengths of the corresponding conductors of the plurality of second conductive elements / elongated buses over which they overlap.

[0121] Once the plurality of first and / or second conductor portions have been overlapped onto the individual front and back sides of the layered structure, the method may further include heating the conductor portions to form an ohmic contact with the underlying surface.

[0122] The method may include heating a plurality of first conductor portions to melt at least a portion of the coating of the conductor portions. The melted coating portion of the conductor may form an ohmic contact with at least one of a plurality of conductive elements / elongated buses of a back electrode assembly over which the conductor overlaps.

[0123] The method may include heating a plurality of second conductor portions to melt at least a portion of the coating of the conductor portions. The melted coating portion of the conductor may form an ohmic contact with at least one of a plurality of front finger electrodes that overlap therewith.

[0124] The individual coating of the conductor portions of the plurality of first and / or second conductor portions may be composed of a material with a melting point lower than that of the core material forming the individual conductor portion. The coatings of the conductor portions of the plurality of first and / or second conductor portions may be heated separately or during the same heating process.

[0125] The first plurality of conductive elements on the front and back sides (e.g., front and back finger electrodes) may be deposited simultaneously (i.e., using a single deposition process) or they may be deposited separately. Once the plurality of first conductive elements have been deposited, the plurality of second conductive elements (e.g., elongated busbars) may be deposited in separate deposition processes.

[0126] The curing temperature for at least one or each of the plurality of first and second conductive elements may be up to 300°C. In an exemplary specific configuration defining the HJT solar cell structure in a layered structure, the curing step may be constructed at a temperature less than 200°C. In an exemplary configuration, the curing temperature may be at least 145°C. The curing temperature may be up to 165°C.

[0127] Those skilled in the art will appreciate that, aside from mutually exclusive cases, features or parameters described in relation to any of the foregoing aspects may apply to any other aspect. Furthermore, aside from mutually exclusive cases, any feature or parameter described herein may apply to any aspect and / or be combined with any other feature or parameter described herein.

Implementation Method

[0129] The aspects and specific details of this disclosure will now be discussed with reference to the accompanying diagrams. Those skilled in the art will understand the further aspects and specific details.

[0130] In the drawings, the thickness of layers, films, etc., is exaggerated for clarity. Furthermore, it will be understood that when an element, such as a layer, film, region, or substrate, is referred to as "on another element," it can be directly on that other element, or there may be an intermediate element present. In contrast, when an element is referred to as "directly on another element," there is no intermediate element present.

[0131] FIG1 shows a solar cell 10 according to the present invention, disposed in a support assembly 102 of a solar panel. The front panel 104 of the support assembly 102 includes a transparent (e.g., glass) sheet, which is configured to allow light to pass through a central cavity 106 in which the solar cell 10 is mounted. The arrow at the top of FIG1 indicates the direction of solar radiation incident on the solar cell 10.

[0132] The back panel 108 of the support assembly 102 is configured to enclose the solar cell 10 within a central chamber 106. The back panel 108 includes a reflective sheet configured to reflect any light incident on its upper surface back toward the solar cell 10. The central chamber 106 is filled with an encapsulating material (the shaded area shown in FIG. 1) to prevent the ingress of external liquid or gaseous objects.

[0133] Solar cell 10 is one of a plurality of solar cells (not shown) disposed in support assembly 102. Each of the plurality of solar cells 10 is electrically coupled together by one or more wires to define solar module 100.

[0134] Figures 2A and 2C illustrate top (front) and bottom (back) views of the solar cell 10, while Figures 2B and 2D show cross-sections of the solar cell 10 along the dashed lines B–B and A–A as shown in Figures 2A and 2C, respectively. The solar cell 10 includes a layered structure 12, a front electrode assembly 14 disposed on the front side 16 of the layered structure 12, and a back electrode assembly 18 disposed on the back side 20 of the layered structure 12. The solar cell 10 has a length as shown in the vertical dimensions of Figures 2A and 2C, and a width as shown in the horizontal dimensions of Figures 2A and 2C.

[0135] The front side 16 defines the surface on the layered structure 12 on which light is incident when the solar cell 10 is in use. The back side 20 defines the surface of the layered structure 12 opposite to the front side 16, as shown in FIG2B.

[0136] As will be further described below, the layered structure 12 is a multilayer semiconductor assembly configured to generate charge carriers by absorbing incident radiation. The front and back electrode assemblies 14 and 18 are each configured to be mounted on the layered structure 12 and to conduct away from the charge carriers generated by the layered structure 12.

[0137] This back electrode assembly 18 includes a plurality of first conductive portions 28 disposed in the first insulating optically transparent film 30, a plurality of first conductive elements 34 disposed on the back side 20 of the layered structure 12, and a plurality of second conductive elements 32 inserted between the plurality of first conductive portions 28 and the plurality of first conductive elements.

[0138] A plurality of second conductive elements 32 are configured to form an ohmic contact between a plurality of first conductive portions 28 and a plurality of first conductive elements 34, wherein the first conductive elements 34 define a plurality of back-side finger electrodes 34 disposed on the back side 20 of the layered structure 12.

[0139] The front electrode assembly 14 includes a plurality of second conductive portions 22 disposed in the second insulating optically transparent film 24, as shown in FIG2B. The plurality of second conductive portions 22 are configured to overlap a plurality of third conductive elements 26, the third conductive elements 26 defining a plurality of front finger electrodes 26 disposed on the front side 16 of the layered structure 12. The conductive portions 22 are configured to form ohmic contacts with the finger electrodes 26.

[0140] The back electrode assembly 18 includes only a plurality of second conductive elements 32 inserted between individual finger electrodes 34 and wire portions 28. The front electrode 16 is configured such that the plurality of second wire portions 22 make direct contact with the finger electrodes 26 disposed on the front side 16 of the layered structure 12, as shown in FIG2B.

[0141] Relatively speaking, the second conductive element 32 of the back electrode assembly 18 is configured to provide an electrical path between the finger electrodes 34 on the back surface 20 of the layered structure 12 and the plurality of first conductive wire portions 28. Accordingly, the conductive element 32 reduces the contact resistivity of the back electrode assembly 18, thereby increasing the fill factor of the solar cell 10. In this way, the conductive element 32 is configured to reduce the resistance loss that would occur if the plurality of first conductive wire portions 28 were configured to directly contact the plurality of back finger electrodes 34.

[0142] The conductive elements 32 are formed of a conductive material such that they are configured to allow charge carriers to flow between the plurality of first conductive portions 28 and the finger electrodes 34 on the back surface 20 of the layered structure 12. In this way, each conductive element 32 defines a current collector for the back electrode assembly 18.

[0143] Each conductive element 32 includes an elongated busbar 32 having a width, length, and depth. The length of each busbar 32 is defined as an axial length substantially greater than its width. The width and length of the busbar 32 are measured in a direction aligned with the plane of the back surface 20 of the layered structure 12.

[0144] The dimensions of each busbar 32 are substantially the same as those of each other busbar 32. For example, the busbars 32 have a common depth such that each protrudes from the back face 20 of the layered structure 12 by the same amount. The depth of each busbar 32 is measured in a direction perpendicular to the plane of the back face 20 of the layered structure 12 (the perpendicular direction shown in FIG. 2B). Furthermore, each busbar 32 has a rectangular cross-section (perpendicular to its length).

[0145] Referring to Figures 2A, 2B, and 2C, the configuration of each of the plurality of finger electrodes 26, 34 and wire portions 22, 28 and bus 32 will now be described in more detail.

[0146] A plurality of front and back finger electrodes 26, 34 are configured to extend across the layered structure 12 in the lateral direction (horizontal direction of FIG. 2A) and to be equally spaced in the longitudinal direction (vertical direction of FIG. 2A).

[0147] The finger electrodes disposed on each of the front and back surfaces 16, 20 of the layered structure 12 are arranged parallel to each other. As shown in Figures 2A and 2C, each of the plurality of front and back finger electrodes 26, 34 contains twelve electrodes. However, it is understood that the number of front and back finger electrodes 26, 34 may vary in some other specific configurations; for example, there may be eighty finger electrodes on each of the front and back surfaces 16, 20. It will be appreciated that the number of finger electrodes may even be greater (e.g., greater than 250) without departing from the scope of the invention. The number of elongated busbars 32 is between 4 and 20, and the number of wire portions 28, 22 is the same as the number of elongated busbars 32.

[0148] Each finger electrode disposed on the front side 16 of the layered structure 12 is aligned with a corresponding electrode from a plurality of back finger electrodes 34.

[0149] The conductor portions of the plurality of first and second conductor portions 28, 22 are parallel in length to the back surface 20 of the layered structure 12 in the longitudinal direction (vertical direction in FIG. 2A). The conductor portions in each of the plurality of conductor portions 28, 22 are also equally spaced in the transverse direction (horizontal direction in FIG. 2A) relative to the back surface 20 of the layered structure 12 to define the longitudinal extension space between the conductor portions. Accordingly, each of the plurality of conductor portions 28, 22 defines an array of parallel, transversely spaced conductor portions.

[0150] Each of the plurality of second conductor portions 22 is aligned with a corresponding conductor portion from the plurality of first conductor portions 28. Each of the plurality of first and second conductor portions 28, 22 comprises sixteen conductor portions disposed on opposite sides of the layered structure 12. Again, in some other specific configurations, the number of conductor portions may vary.

[0151] Now turn to a plurality of elongated busbars 32 that extend longitudinally (vertically in FIG. 2A) across the back surface 20 of the layered structure 12. Similar to the wire portion, the busbars 32 are also arranged parallel to each other and are equally spaced laterally (horizontally in FIG. 2A). Thus, the spacing between the busbars 32 defines an array of longitudinally extending spaces therebetween.

[0152] According to the above configuration, a plurality of front and back finger electrodes 26, 34 are configured to be perpendicular to a plurality of first and second wire portions 22, 28, and also perpendicular to a plurality of elongated busbars 32, as shown in Figures 2A and 2C.

[0153] As illustrated in Figures 2B and 2C, the back electrode assembly 18 is provided with sixteen buses 32. Each of the sixteen buses overlaps with a conductor portion from a plurality of first conductor portions 28. The axial length of each conductor portion of the plurality of first conductor portions 28 is axially aligned with the axial length of the corresponding bus of the plurality of elongated buses 32 over which they overlap. Thus, the plurality of first conductor portions 28 are directly stacked on top of the plurality of elongated buses 32 on the back surface 20 of the layered structure 12. Advantageously, the alignment between the buses 32 and the conductor portions 28 limits the proportion of additional shielding caused by the buses 32.

[0154] The parallel alignment between the bus 32 and the conductor portion 28 also increases the contact area at the interface between the conductor portion and the elongated bus, thereby reducing the resistivity of the contact. Therefore, the solar cell 10 is configured to maintain a similar short-circuit current (i.e., due to similar shading) while increasing the fill factor by reducing the resistivity at the contact interface.

[0155] The width of each elongated busbar 32 is less than 0.25 mm, significantly smaller than the width of buses on conventional solar cells. Compared to conventional busbar configurations, the narrower busbar width allows for the arrangement of more buses 32 across the back surface 20 of the layered structure 12. The larger number of buses 32 thereby generates more current extraction paths within the solar cell 10.

[0156] Furthermore, each bus 32 is constructed with a width slightly greater than the thickness of the covered conductor portion 28. The larger width of the elongated bus 32 ensures good electrical contact at the interface between the conductor portion 28 and the elongated bus, which reduces the resistivity of the connection between the plurality of first conductor portions 28 and the back finger electrode 32.

[0157] By constructing each elongated busbar 32 with a width slightly wider than the thickness of the wire portion, good electrical contact is ensured, even if there is a minor misalignment between the wire portion and the busbar during the fabrication of the back electrode assembly 18.

[0158] The elongated busbar 32 shown in FIG2C has straight longitudinal edges. According to an alternative configuration of the invention, the longitudinal edges may be constructed to include a plurality of straight or curved facets, as shown in FIG4A and 5 respectively. Referring particularly to FIG4B, the conductor receiving surface of each elongated busbar 132 defines a periodic or repeating rhombus. Alternatively, the conductor receiving surface may include a plurality of curved facets to define a periodic (or repeating) sector, as shown in FIG5.

[0159] In each exemplary configuration shown in Figures 4A, 4B, and 5, the widest portion of the elongated busbars 132 and 232 corresponds to the portion overlapping with the finger electrodes 32, and the narrowest portion corresponds to the space between the finger electrodes 32. In this way, the elongated busbars 132 and 232 are configured to maximize the contact area with the finger electrodes 32 while minimizing the overall size of the busbars, thereby reducing associated material costs.

[0160] The elongated busbar 32 is formed of a conductive material, which is a metal alloy containing Ag. The conductive material is a printing material that allows the busbar 32 to be easily deposited onto the back surface 18 of the layered structure 12. The printing material is formed using a printable precursor, such as a conductive paste, which contains a mixture of silver metal powder and glass frit suspended in a solvent. As will be described in more detail below, the conductive paste may be fired or cured to form the elongated busbar.

[0161] The plurality of first and second finger electrodes 26 and 34 are each formed using a printed conductive material similar to that used to form the plurality of elongated busbars 32.

[0162] The conductor portions 22 and 28 each have a circular transverse cross-sectional shape (i.e., transverse to the axial length of the conductor portion), as shown in Figure 2A. Each conductor portion is formed by an axial core, which is made of a conductive metal alloy. The core of the conductor portion is covered by an outer conductive coating.

[0163] The core of the conductor is made of copper, and the outer cladding is made of a material with a lower melting point than the core. The outer cladding may contain a metal alloy, such as a lead-based alloy.

[0164] According to the exemplary configuration of the solar cell 10, each of the plurality of first and second conductive portions 28, 22 is attached to the surface of its individual film 30, 24 facing the layered structure 12. The layered-structure-facing surface of each film 30, 24 is coated with an adhesive to adhere the conductive portion to its individual film 30, 24.

[0165] Referring to FIG. 2D, in the case of the front electrode assembly 14, the membrane 24 is configured to contact the front side of the layered structure 12 in the region between the lead wire portion 22 and the front finger electrode 26. In the case of the back electrode assembly 18, the membrane 30 is configured to contact the back side 20 of the layered structure 12 in the region between the lead wire portion 28, the elongated busbar 32, and the back finger electrode 34.

[0166] In a specific configuration of the solar cell 10, at least one or each of the first and second films 30, 24 is configured to at least partially (e.g., completely) cover or surround individual conductive portions 28, 22 and individual finger electrodes 34, 26, as shown in Figures 1 and 2B. In the case of the back electrode assembly 18, the film 30 may also at least partially (e.g., completely) cover the elongated busbar 32.

[0167] The first and second membranes 30, 24 are configured to provide adhesion between the layered structure 12 and the wire portions 28, 22, such that the wire portions are correctly positioned on the layered structure 12 (i.e., aligned with the elongated busbar and the finger electrodes). In an exemplary specific embodiment, the first and second membranes 30, 24 may not completely cover the surface of the layered structure 12.

[0168] The first and second membranes 30 and 24 shown in the figure respectively include a substantially flat bottom surface and a top surface. However, it will be understood that the membranes may be constructed to conform to the structural members of their individual electrodes. For example, the membrane 30 of the back electrode assembly 18 may conform to the finger electrodes 34, busbars 32, and lead wire portions 28 disposed on the back surface 20 of the layered structure 12. According to this exemplary configuration, the membrane 30 may be composed of elongated channels, recessed toward the layered structure in the region between the lead wire portions and busbars of the back surface 20, and may form ridges / protrusions on the electrode structures (such as busbars and lead wire portions) where they appear.

[0169] The third membrane 30 is applied to the bottom of the layered structure by heat and pressure, so that the membrane 24 will conform to the elongated busbar and the back finger electrode. The second membrane 24 may also be applied to the top of the layered structure by heat and pressure, so that it conforms to the front finger electrode disposed thereon.

[0170] According to an alternative exemplary configuration, membranes 30 and 24 may include channels disposed on their individual layered structures facing surfaces. The channels may be configured to provide a tight fit around the corresponding elongated busbars and finger electrodes.

[0171] The first and second membranes 30 and 24 are generally thinner than the wire portions 28 and 22. For example, the wire portions may have a thickness of about 200 to 300 micrometers, while the membranes have a thickness of about 100 micrometers.

[0172] The first and second films 30 and 24 are each formed of a polymeric material and possess high toughness, good insulation properties, optical transparency, thermal stability, and shrinkage resistance. The exemplary polymeric material is composed of modified ethyl tetrafluoroethylene.

[0173] FIG3 is a cross-sectional view of the layered structure 12 of the solar cell 10 according to FIGS. 2A, 2B, and 2C. In this figure, the layered structure 12 is shown isolated from the front and back electrodes 14 and 18. FIG3 is an exemplary layered structure 12, and in some other specific embodiments, the layered structure may differ from that shown in FIG3. For example, in some other specific embodiments, there may be no one or more layers, one or more layers may be combined together, and / or additional layers may be added, provided that the layered structure 12 can continue to perform its function of generating electricity from incident radiation (e.g., light).

[0174] The layered structure 12 includes a multilayer semiconductor component 60, including a photovoltaic element 62 sandwiched between an emitter layer 64 and a back field layer 66. Thus, the emitter layer 64 and the back field layer 66 are arranged on opposite sides of the photovoltaic element 62.

[0175] The emitter layer 64 is configured to face the front side 16 of the layered structure 12, and the back field layer 66 is configured to face the back side 20. The front electrode assembly 14 is electrically connected to the emitter layer 64, and the back electrode assembly 18 is electrically connected to the back field layer 66. This configuration defines a heterojunction technology (HJT) type solar cell.

[0176] The photovoltaic element 62 is formed of crystalline silicon (c-Si) and negatively doped with group V elements such as phosphorus (P), arsenic (As), and antimony (Sb) (i.e., n-type material). The emitter layer 64 and the back field layer 66 are each formed of amorphous silicon (a-Si:H). The amorphous silicon is deposited on the front and back sides of the silicon wafer using plasma-enhanced chemical vapor deposition (PECVD).

[0177] The emitter layer 64 contains a positively doped semiconductor material (i.e., a p-type material), and the back field layer 66 contains an n-type material. The p-type material contains impurities of group III elements, such as boron (B), gallium (Ga), and indium (In).

[0178] According to the exemplary configuration of the layered structure 12, the emitting layer 64 defines the impurity region of the layered structure having a conductivity type opposite to that of the photovoltaic element 62, thus forming a pn junction together with the photovoltaic element 62.

[0179] The multilayer semiconductor component 60 further includes first and second intrinsic layers 74 and 76. Intrinsic layers 74 and 76 are both formed of intrinsically doped amorphous silicon. The first intrinsic layer 74 is disposed between the emitter layer 64 and the photovoltaic element 62 to form a front passivation layer. Incidentally, the second intrinsic layer is disposed between the photovoltaic element 62 and the back field layer 66 to form a back passivation layer.

[0180] Finally, the front side 16 of the layered structure 12 is covered with a transparent conductive coating 68 formed of indium tin oxide (ITO). The upper surface 70 of the ITO layer is textured to provide anti-reflective features. The anti-reflective layer advantageously reduces the reflectivity of light incident on the solar cell and increases the selectivity of a predetermined wavelength band, thereby increasing the efficiency of the solar cell.

[0181] The back surface 20 of the layered structure 12 is also covered with a transparent conductive coating 72 formed of indium tin oxide (ITO). The transparent conductive coatings 68 and 72 are configured to increase lateral carrier transport to the finger electrodes disposed on the individual surfaces of the layered structure 12. The transparent conductive coatings 68 and 72 are particularly advantageous in heterojunction devices that contain layers formed of amorphous silicon and exhibit poor carrier mobility.

[0182] During the operation of the solar cell 10, light is incident on the layered structure, as indicated by the arrow at the top of Figure 3. Multiple electron-hole pairs are generated through the absorption of the incident photons. The electron-hole pairs are then separated into electrons and holes by a built-in potential difference originating from the pn junction. The separated electrons move to the n-type semiconductor in the photovoltaic element 62, and the separated holes move to the p-type semiconductor in the emitter layer 64. Accordingly, electrons become the dominant carriers in the photovoltaic element 62, and holes become the dominant carriers in the emitter layer 64. Each of these dominant carriers is drawn from the layered structure 12 by individual electrodes 14, 18.

[0183] An exemplary method 200 for manufacturing a solar cell 10 will now be described with reference to FIG6, which illustrates a flowchart of the corresponding method steps.

[0184] The method begins in a first step 202, in which a layered structure 12 comprising photovoltaic elements is provided. According to an exemplary configuration, the layered structure 12 is constructed to include a semiconductor component 60, as described above with reference to FIG3.

[0185] The method then proceeds to step 204, wherein conductive portions are constructed on the front and back sides 16, 20 of the layered structure 12. This is achieved by depositing conductive material onto the front and back sides 16, 20 of the layered structure to form a plurality of front and back finger electrodes 26, 34, respectively.

[0186] Once a plurality of back-side finger electrodes 34 are deposited onto the back-side surface 20 of the layered structure 12, the method may proceed to step 206, wherein a plurality of elongated buses 32 are deposited onto the layered structure 12. The buses 32 are formed by depositing conductive material onto the back-side surface 20 of the layered structure 12 in a predetermined pattern. In particular, the method includes constructing the buses 32 to be arranged perpendicular to the plurality of back-side finger electrodes 34, thereby forming an electrical connection thereto.

[0187] Each of the plurality of front and back finger electrodes 26, 34 and the plurality of elongated busbars 32 is deposited onto its individual surface using a screen printing process. The screen printing process involves laying a printable precursor onto the surface of the layered structure through a screen or mask. The openings in the mask determine the individual configuration and size of the printed features (i.e., the finger electrodes and busbars). Once each individual printable precursor is provided onto the surface of the layered structure, it is fired in a furnace to form the corresponding finger electrode and / or elongated busbar features.

[0188] A method for depositing a plurality of back-side finger electrodes 34 includes depositing a first conductive material onto a back-side 20. The method includes depositing a first printable precursor and then curing it according to a first firing process.

[0189] The method of depositing a plurality of elongated busbars 32 includes depositing a second conductive material onto the back surface 20 of the layered structure 12. The method includes depositing a second printable precursor and then curing it according to a second firing process.

[0190] A method for depositing a plurality of front-side finger electrodes 26 includes depositing a third conductive material onto the front side 16. The method includes depositing a third printable precursor and then curing it according to a third firing process.

[0191] Because the busbar 32 is configured relative to the back finger electrode 34, once a plurality of back finger electrodes 34 have been formed (i.e. after the first firing step is completed), the second printable precursor is deposited only on the back side 20 of the layered structure 12.

[0192] The first printable precursor is deposited using a different printing mask than that used to deposit the second printable precursor, corresponding to the back finger electrode 34. The different printing masks contain openings of different sizes, thereby altering the alignment and size of the resulting busbar 32 relative to the finger electrode 34.

[0193] Each of the first, second, and third printable precursors comprises a metal paste, which is obtained by mixing metal powder and glass frit together in the presence of a suitable solvent.

[0194] The plurality of front and back finger electrodes 26, 34 are substantially identical. Therefore, the first and third printable precursors are composed of substantially the same chemical composition. Furthermore, the first and third firing processes each have the same firing parameters (e.g., firing temperature and duration).

[0195] The plurality of busbars 32 are formed from compositions different from the front and back finger electrodes 26, 34. Therefore, the second printable precursor is substantially different from the first and third printable precursors. Furthermore, the first firing process includes firing parameters different from the second and third firing processes.

[0196] As part of the method described above, elongated busbars 32 are disposed at predetermined locations on the back surface 20 of the layered structure 12 such that they can overlap with a plurality of first conductor portions 28. The method includes a pre-alignment step, wherein the busbars 32 are positioned on the back surface 20 to ensure that the conductor portions 28 will correctly overlap onto the busbars 32 during subsequent method steps 208, 210.

[0197] Once the elongated busbar 32 is deposited onto the back surface 20 of the layered structure 12 (i.e., after the busbar 32 has been fired), a plurality of first conductor portions 28 can be overlapped on top of the busbar 32. First, each conductor portion 28 is axially aligned with the corresponding busbar 32 that constitutes the receiving conductor portion 28. Then, once each of the plurality of first conductor portions 28 is suitably aligned with the associated busbar 32, the conductor portion 28 is placed on the busbar 32 in step 210.

[0198] According to the above method, the axial length of each conductor portion 28 is configured to be parallel to the axial length of the busbar 32 it overlaps with. Furthermore, each conductor portion 28 is configured to be perpendicular to a plurality of finger electrodes 26, 34 on the front and back sides 16, 20 of the layered structure 12, as shown in each of Figures 2C, 4A, 4B, 5.

[0199] After depositing a plurality of elongated busbars 32, a plurality of second conductive portions 22 may also be disposed on the layered structure 12. In step 208, the conductive portions 22 are overlapped onto the front surface 18 of the layered structure 12, such that they are positioned as a plurality of front-facing finger electrodes 26 perpendicular to the front surface 16 of the layered structure 12, as shown in FIG2A. The method of overlapping the plurality of first and second conductive portions 28, 22 may be performed simultaneously or sequentially and in any order.

[0200] The method of configuring the wire portions 28, 22 includes the step of heating the wire portions 28, 22 in a furnace to bond the wire portions to the surfaces where they overlap. A plurality of first and second wire portions 28, 22 each have an outer coating that partially melts upon heating.

[0201] The outer sheath on the conductor portion of the plurality of second conductor portions 22 forms an ohmic contact with the lower finger electrode 26 disposed on the front side 16 of the layered structure 12, while heating the plurality of first conductor portions 28 causes the sheath to form an ohmic contact with the elongated busbar 32 disposed on the back side 20.

[0202] It will be understood that the present invention is not limited to the specific embodiments described above, and various modifications and improvements can be made without departing from the concept described herein. Except in mutually exclusive cases, any feature may be used separately or in combination with any other feature, and this disclosure extends to and includes all combinations and sub-combinations of one or more features described herein. [Simplified Explanation of the Diagram]

[0128] The specific configuration will now be described by way of example only with reference to the figures, in which: [Fig. 1] is a close-up cross-sectional view of a solar module containing solar cells; [Figs. 2A and 2C] are plan views of the top (front) and bottom (back) of the solar cell of Fig. 1, respectively; [Figs. 2B and 2D] are cross-sectional views through different parts of the solar cell shown in Figs. 2A and 2C; [Fig. 3] is a three-dimensional cross-sectional view of the semiconductor layered structure of the solar cell of Fig. 1; [Fig. 4a] is a plan view of the bottom (back) of the solar cell, including the alternative selective architecture of the bus; [Fig. 4b] is a close-up view of the bottom (back) of the solar cell shown in Fig. 4a; [Fig. 5] is a plan view of the bottom (back) of the solar cell, including the alternative selective architecture of the bus; and [Fig. 6] is a flowchart demonstrating a method for manufacturing the solar cell of Fig. 1.

Claims

1. A solar cell module, comprising: a layered structure including photovoltaic elements; a back electrode assembly disposed on the back side of the layered structure, the back electrode assembly comprising: a plurality of wire portions and a plurality of first conductive elements disposed on the back side of the layered structure; And a plurality of second conductive elements, inserted between the plurality of wire portions and the plurality of first conductive elements; And a front electrode assembly disposed on the front side of the layered structure opposite to the back side; wherein the plurality of first conductive elements are configured to form an ohmic contact between the plurality of second conductive elements and the back side of the layered structure, and the plurality of second conductive elements are configured to form an ohmic contact between the plurality of first conductive elements and the plurality of wire portions; and wherein only the back electrode assembly includes a plurality of second conductive elements inserted between the plurality of wire portions and the plurality of first conductive elements.

2. The solar cell module according to claim 1, wherein the plurality of conductive portions of the back electrode assembly define a plurality of first conductive portions, wherein the front electrode assembly includes a plurality of second conductive portions configured to form ohmic contacts with a plurality of third conductive elements of the front electrode assembly, the plurality of third conductive elements being interposed between the plurality of second conductive portions and the front side of the layered structure.

3. The solar cell module according to claim 1 or 2, wherein the plurality of second conductive elements define a plurality of elongated busbars.

4. The solar cell module according to claim 3, wherein at least one of the plurality of conductor portions is configured to at least partially overlap at least one of the plurality of elongated buses.

5. The solar cell module according to claim 4, wherein the elongated busbar is configured to be substantially parallel to the conductor portion.

6. The solar cell module according to claim 5, wherein at least one of the plurality of elongated buses has a width measured in a plane on the surface of the layered structure, the width of the elongated bus being at least equal to the thickness of the conductive portion measured in a plane on the surface of the layered structure.

7. The solar cell module according to claim 6, wherein the width of the elongated busbar is substantially the same as or less than the thickness of the conductor portion.

8. The solar cell module according to claim 6, wherein the width of the elongated busbar is less than 0.7 mm.

9. The solar cell module according to claim 6, wherein the width of the first portion of the elongated busbar is greater than the thickness of the conductor portion, and / or wherein the width of the second portion of the elongated busbar is substantially the same as the thickness of the conductor portion, and / or wherein the width of the third portion of the elongated busbar is less than the thickness of the conductor portion.

10. The solar cell module according to claim 6, wherein the width of the elongated busbar varies along its length.

11. The solar cell module according to claim 10, wherein the longitudinal edge of the elongated busbar includes a plurality of straight or curved facets.

12. The solar cell module according to claim 10, wherein the width of the elongated busbar varies along its length to define a rhombus or a fan shape.

13. The solar cell module according to claim 3, wherein each of the plurality of first conductor portions is configured as a corresponding conductive element overlapping the plurality of elongated busbars.

14. The solar cell module according to claim 13, wherein the axial length of each of the plurality of first conductor portions is substantially parallel to the axial length of the corresponding conductive element of the plurality of elongated busbars to which they overlap.

15. The solar cell module of claim 3, wherein the plurality of first conductive elements comprises a plurality of finger electrodes, wherein at least one of the plurality of finger electrodes is substantially misaligned in the length direction with at least one of the plurality of elongated buses overlapping the finger electrode.

16. The solar cell module according to claim 15, wherein the at least one finger electrode is substantially vertically configured relative to the at least one elongated busbar.

17. A solar cell module according to claim 1 or 2, wherein at least one of the plurality of first and second conductive elements is formed using a printed material.

18. A solar module comprising a plurality of solar cell modules according to any one of claims 1 to 17, wherein the plurality of solar cell modules are electrically coupled together.

19. The solar module according to claim 18, comprising a first solar cell module electrically coupled to a second solar cell module, wherein the plurality of wire portions of the first solar cell module are electrically coupled to the plurality of wire portions of the second solar cell module.

20. A method of manufacturing a solar cell module, comprising: providing a layered structure including photovoltaic elements; configuring a back electrode assembly onto the back side of the layered structure, wherein configuring the back electrode assembly comprises: constructing a plurality of first conductive elements onto the back side of the layered structure to form ohmic contacts therewith; constructing a plurality of second conductive elements onto the plurality of first conductive elements to form ohmic contacts therewith; configuring a plurality of wire portions onto the plurality of second conductive elements to form ohmic contacts therewith; and configuring a front electrode assembly onto the front side of the layered structure; wherein configuring only the back electrode assembly comprises constructing a plurality of second conductive elements interposed between the plurality of wire portions and the plurality of first conductive elements.

21. The method of claim 20, wherein the plurality of conductive portions of the back electrode assembly defines a plurality of first conductive portions, wherein configuring the front electrode assembly comprises: constructing a plurality of third conductive elements onto the front surface of the layered structure to form ohmic contact therewith; and configuring a plurality of second conductive portions onto the plurality of third conductive elements to form ohmic contact therewith.

22. The method of claim 20 or 21, wherein constructing the plurality of first conductive elements comprises depositing a first printed material onto the surface of the layered structure to form a plurality of finger electrodes.

23. The method of claim 22, wherein constructing the plurality of second conductive elements comprises depositing a second printed material onto the surface of the layered structure to form a plurality of elongated busbars.

24. The method of claim 23, wherein depositing the first printable material comprises depositing a first printable precursor and then firing the first printable precursor according to a first firing process, and wherein depositing the second printable material comprises depositing a second printable precursor and then firing the second printable precursor according to a second firing process, wherein the first printable precursor is deposited onto the surface of the layered structure only after the second firing process is completed.

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