Electrode Assembly

Abstract

1. An electrode assembly for connecting a front surface of a first solar cell to a back surface of a second solar cell, the electrode assembly comprising a plurality of conductive elements, at least one of the conductive elements having a first surface for contacting a front surface of the first solar cell and a second surface for contacting a back surface of the second solar cell, the second surface being disposed opposite the first surface, at least a portion of each of the first and second surfaces comprising a coating for connecting a respective surface of the at least one conductive element to a surface of the solar cell, the second surface being configured to define a contact area substantially smaller than the contact area defined by the first surface.

Description

[Technical field]

[0001] SUMMARY The present disclosure relates to an electrode assembly for a solar cell assembly, a solar cell assembly, and a method for manufacturing a solar cell assembly. [Background technology]

[0002] A solar module for providing electrical energy from sunlight comprises an array of cells, each of which comprises a photovoltaic element or substrate. The solar cells are typically connected such that electrical current flows from the front surface of one solar cell to the back surface of a second solar cell, or vice versa, via electrical connectors. Each of the electrical connectors comprises a plurality of conductive elements (e.g., interconnect wires) that form electrical connections with electrodes disposed on the front and back surfaces of each of the solar cells.

[0003] A general objective for solar cell development is to achieve high conversion efficiency balanced with the need for reduced production costs. Efforts to achieve this have focused on the electrical connections between the solar cells.

[0004] One approach has been to provide foil wire electrodes that connect directly to finger electrodes placed on the surface of each solar cell. The foil wire electrodes reduce electrical losses by minimizing the impact of cell damage on the performance of the solar cell module. Furthermore, the use of foil wire electrodes can also lead to a significant reduction in module production costs and optical losses resulting from light shading caused by configuring the surface of the solar cells with conventional printed busbar electrodes.

[0005] However, despite these developments, there is still a need to improve the contact between the electrodes of solar cells in order to increase their power conversion efficiency. Summary of the Invention

[0006] According to a first aspect of the present invention, an electrode assembly for connecting a front surface of a first solar cell to a back surface of a second solar cell is provided. The electrode assembly comprises a plurality of conductive elements. At least one of the conductive elements comprises a first surface for contacting the front surface of the first solar cell and a second surface for contacting the back surface of the second solar cell. The second surface is disposed opposite the first surface. At least a portion of each of the first and second surfaces comprises a coating for connecting the respective surface of the at least one conductive element to a surface of the solar cell (e.g., the front and back solar cell surfaces). The second surface is configured to define a contact area (e.g., a contact area with a back surface of the second solar cell) that is substantially smaller than the contact area defined by the first surface (e.g., a contact area with the front surface of the first solar cell).

[0007] When the electrode assembly is in use, the first surface of the at least one conductive element may be arranged to contact the front surface of the first solar cell and face away from the back surface of the second solar cell. Thus, the second surface may be arranged to contact the back surface of the second solar cell and face away from the front surface of the first solar cell. The larger contact area defined by the first surface improves the connection between the coating and the front surface of the first solar cell. This improves the connectivity of the electrode assembly to the solar cell, thereby increasing the fill factor of the solar cell assembly.

[0008] The coating may be configured to form an electrical and / or physical (e.g., mechanical) connection with a surface of the solar cell. The coating may be a solderable coating, i.e., a coating configured to solder a conductive element to the surface of the solar cell.

[0009] The second surface, which defines a smaller contact area, is configured to increase scattering of light incident on the front surface of the first solar cell. The smaller dimensions also reduce obscuration of the front surface so that more light can be absorbed by the first solar cell.

[0010] The electrode assembly is effectively configured such that the first surface of the conductive element faces away from the back surface of the second solar cell. This arrangement may increase the shading of light incident on the back surface of the solar cell (e.g., because the first surface of the conductive element has a larger surface area relative to the second surface). However, any possible increase in light shading on the back surface of the solar cell has only a limited effect on the overall light absorption characteristics of the solar cell (e.g., because light mainly enters the front surface of the cell), and therefore does not significantly affect the performance of the solar cell.

[0011] During construction of the solar cell assembly, the electrode assembly may be connected (e.g., laminated) on the front and back surfaces of each of the first solar cell and the second solar cell. At least one of the first solar cell and the second solar cell may be inverted so that their front surfaces are arranged to face substantially downward (e.g., substantially vertically downward) and their back surfaces are arranged to face substantially upward (e.g., substantially vertically upward). In this situation, the electrode assembly according to the present invention is effectively configured to form a robust and conductive electrical connection with the contact surfaces of each of the first solar cell and the second solar cell.

[0012] In particular, the first surface of the conductive element can be connected to the downwardly facing front surface of the first solar cell. The connection may be formed by applying heat and pressure to the coating on the first surface to form a mechanical and electrical connection with the surface of the solar cell. The weight of a material positioned vertically on the first surface of the conductive element (e.g., a solar cell and / or other components of a solar cell assembly disposed on top of the conductive element) may help prevent the coating from flowing away from the contact interface with the first solar cell. In addition, the relatively large contact area of ​​the first surface of the conductive element may prevent the coating from flowing away from the contact interface due to gravity. In this way, the larger contact area of ​​the first surface can hold the coating at the interface with the solar cell, thereby ensuring the formation of a good electrical connection.

[0013] Also, the second surface of the conductive element can be connected to the upwardly facing back surface of the second solar cell. In this case, the relatively small contact area of ​​the second surface of the conductive element causes the coating to flow due to gravity toward the interface between the second surface of the conductive element and the back surface of the second solar cell. This allows the coating to accumulate or pool at the interface with the back surface of the second solar cell, thereby ensuring a good electrical connection. In this way, the difference between the respective contact areas of the first and second surfaces of the conductive element forms a physical gradient that preferentially guides the coating toward the respective interfaces with the front and back surfaces of the solar cell. This effect is particularly advantageous in embodiments in which the coating comprises a material (e.g., a metal alloy) with a relatively low melting point (compared to the conductive element below the coating) that melts during lamination of the solar cell assembly components (e.g., in foil wire bonding technology).

[0014] Generally, the at least one conductive element is configured to improve the electrical path between the first solar cell and the second solar cell while simultaneously enhancing the light scattering and absorption conditions at the front surface of the first solar cell. Thus, the conductive element reduces the contact resistivity of the electrode assembly, thereby increasing the fill factor of the solar cell assembly. In other words, the conductive element is configured to reduce the resistance losses caused by poor contact interfaces between the electrode assembly and the respective contact surfaces of the solar cells. As a result, the electrode assembly can increase the output of the solar cell assembly (and thus the solar module). Also, by improving the electrical connection between the electrode assembly and the solar cells, the reliability of the solar cell assembly is increased, thereby extending the operational life of the solar module and reducing the associated maintenance costs.

[0015] The following are optional features that can be applied alone or in any combination with any aspect.

[0016] The front surface of the solar cell may define a surface of the solar cell on which light is incident when the solar cell assembly is in use (e.g., the front-most surface of the solar cell). The back surface of the solar cell defines a surface of the solar cell opposite the front surface (e.g., the back-most surface of the solar cell). The back surface of the solar cell may not be directly exposed to incident light during use. The solar cell assembly may be configured such that light that is transmitted through the solar cell from the front to the back (e.g., not absorbed) is then reflected towards the back surface of the solar cell, thereby providing further opportunity for the light to be absorbed.

[0017] The conductive elements may be configured to form ohmic contacts with the conductive surfaces (e.g., conductive portions of the surfaces) of the solar cells. Each of the solar cells may comprise a layered structure including a photovoltaic element, as would be understood by one of skill in the art. The conductive surfaces may comprise one or more finger electrodes disposed (e.g., printed) on the front and back surfaces of the solar cells and conducting charge carriers generated by the layered structure.

[0018] It is understood that the terms "conductive" and "insulating" as used herein are expressly intended to mean electrically conductive and electrically insulating, respectively. The meaning of these terms is particularly clear when considering the technical context of the present disclosure, i.e., the context of a photovoltaic solar cell device. It is also understood that the term "ohmic contact" is intended to mean a non-rectifying electrical junction (i.e., a junction between two conductors that exhibits a substantially linear current-voltage (IV) characteristic).

[0019] Each of the conductive elements may have an elongated form, such as a wire or a portion of a wire. At least one, or each, of the conductive elements may comprise a single, integrally formed element (e.g., a wire). Configuring the conductive elements in this manner eliminates the need for separate connections (such as copper ribbons) between adjacent solar cells, thereby reducing the number and complexity of manufacturing steps required to fabricate a solar cell assembly.

[0020] The conductive elements described herein may form part of a "foil-wire" electrode assembly in which the conductive elements are initially held by a foil (e.g., a transparent insulating film) before being placed on the surface of the solar cell (e.g., foil-wire bonding techniques). In such embodiments, a coating may be disposed on the first surface and / or the second surface of the conductive element (e.g., to define a solid coating) before attaching the conductive element to the foil. The coating may comprise a material having a lower melting point compared to the underlying conductive element, such that the coating melts during lamination of the electrode assembly onto the solar cell.

[0021] Alternatively, the conductive element may form part of a multi-busbar electrode assembly, in which the conductive element is placed on the surface of the solar cell (e.g., individually placed and held against the surface of the solar cell) before being soldered in place (e.g., to define a multi-busbar connection technique). When used in a multi-busbar electrode assembly, a coating on the first surface and / or second surface of the conductive element may define a solder (e.g., an electrically conductive solder material) that mechanically and electrically connects the conductive element to the solar cell surface. In an embodiment, the conductive element may define two or more separate components (e.g., two or more wire portions) that are electrically connected to form a single conductive element. For example, the conductive element may comprise a first conductive element portion for contacting a front surface of a first solar cell and a second conductive element portion for contacting a back surface of a second solar cell. Each of the first and second conductive element portions may comprise a first and second surface as described above. The first and second conductive element portions can be electrically connected by a third conductive element portion (e.g., a copper ribbon) to allow electrical current to flow between the first and second conductive element portions. The third conductive element portion can be substantially parallel or substantially perpendicular to the first and second conductive element portions.

[0022] The conductive elements may be formed from a conductive material, such as a metal or metal alloy material, which may include at least one of Ag, Al, Au, and Cu.

[0023] The first surface and the second surface may define an upper or lower surface of the conductive element. At least one or each of the first surface and the second surface may extend longitudinally along a length of the conductive element. The first surface may be disposed diametrically opposite the second surface of the conductive element.

[0024] The contact area of ​​the first surface may be defined at least in part by the width of the first surface that is placed in contact or near contact with the front surface of the solar cell. Similarly, the contact area of ​​the second surface may be defined at least in part by the width of the second surface that is placed in contact or near contact with the back surface of the solar cell. In this manner, the first surface may be configured to have a contact width that is greater than the contact width of the second surface.

[0025] It is understood that the first surface and the second surface each define a surface (e.g., flat or curved) of the conductive element. Such surfaces clearly form an end of the conductive element that can be formed between two adjacent surfaces. For example, in the case of a wire having a triangular (e.g., triangular-shaped) cross section, the base of the triangle can be considered to define a surface. However, the apex of the triangular cross section can be considered to define an end that defines a junction between two angled surfaces. Thus, a triangular cross section wire does not have first and second opposing surfaces as defined in accordance with the present invention. Thus, at least one conductive element may not have a triangular (e.g., triangular-shaped) cross section.

[0026] In an embodiment, the respective first and second contact areas may also be defined, at least in part, by the length of the conductive element configured to overlap, in use, the front and back surfaces of the first and second solar cells, respectively. The electrode assembly may be configured such that the length of the conductive element overlapping the front surface of the first solar cell is substantially equal to the length of the conductive element overlapping the back surface of the second solar cell. In this situation, the contact area may be substantially defined by the width of each of the first and second surfaces.

[0027] The conductive elements may be configured to have a cross-sectional shape that is asymmetric about a central lateral plane of the conductive element (i.e., a width-wise or horizontally extending plane passing through the longitudinal axis of the conductive element). The or each conductive element may be configured to have a cross-sectional shape that is symmetric about a central vertical plane of the conductive element (i.e., a depth-wise or vertically extending plane passing through the longitudinal axis of the conductive element).

[0028] At least one, or each, of the conductive elements may have a substantially constant cross-section along its length.

[0029] Each conductive element may be arranged such that the first surface and the second surface maintain their respective positions on the conductive element when the element is connected between the first solar cell and the second solar cell. In other words, each conductive element may be configured to be free of any axial twists or kinks along its length.

[0030] At least one or each of the conductive elements may have a substantially flat first surface. In this manner, the first surface may define a substantially planar surface facing the front surface of the first solar cell. In an embodiment, the first surface may be configured to be substantially parallel to the front surface of the first solar cell. The flat first surface may provide a planar contact area that can hold the coating at an interface with the solar cell surface, thereby forming a better electrical contact.

[0031] The flat first surface is particularly advantageous in situations where the solar cell is inverted during connection to the electrode assembly, as described above. In such situations, the first surface of the conductive element is arranged to face substantially upward (e.g., vertically upward). Thus, when heat and / or pressure is applied to the conductive element to form a connection with the solar cell surface, the coating is supported on the flat surface, thereby preventing it from flowing away from the contact interface with the solar cell surface due to gravity. It is understood that the above advantageous arrangement can be achieved with a substantially non-convex first surface (e.g., including a substantially flat or substantially concave surface relative to the body of the conductive element).

[0032] The second surface of the or each conductive element may be substantially curved. The second surface may be curved outwardly from the conductive element (e.g., the surface curves away from the longitudinal axis of the conductive element). The second surface may be substantially convex (e.g., convex with respect to the body of the conductive element). The shape of the outwardly curved second surface may define an arc when viewed from a cross-section of the conductive element. The outwardly curved shape may be configured to terminate at the first surface. In an embodiment, at least one conductive element may comprise a cross-section shaped as an elliptical segment (e.g., an oval or short circle), such as a circular segment (e.g., an oval or short circle). In an embodiment, at least one conductive element may have a semi-elliptical cross-section, such as a semicircular cross-section.

[0033] In an embodiment, the second surface may be substantially flat. The first surface may be substantially parallel to the second surface. The second surface may be configured to be substantially parallel to a back surface of the second solar cell.

[0034] At least one conductive element may include a third surface disposed between the first surface and the second surface. The third surface may be configured to space the first surface from the second surface. The conductive element may include a fourth surface disposed opposite the third surface. At least one of the third surface and the fourth surface may define a depth of the conductive element.

[0035] At least one of the third surface and the fourth surface may be substantially flat. In an embodiment, at least one, or each, of the conductive elements may have a cross-sectional shape defining a truncated triangle.

[0036] At least one of the third surface and the fourth surface may be substantially curved. At least one of the third surface and the fourth surface may be configured to curve outwardly from the conductive element (e.g., substantially convex). In an embodiment, at least one or each of the conductive elements may have a cross-sectional shape that defines a truncated elliptical segment (e.g., a truncated oblong or short elliptical segment). In an embodiment, the cross-sectional shape may define a truncated semicircle.

[0037] It should be understood that the term "curved" includes a chain of straight segments arranged at an angle to one another such that although each segment is straight, the overall shape of the chain is curved.

[0038] The coating (i.e., the solderable coating) may include a conductive material having a melting point lower than the melting point of the conductive element. The coating may include a metal alloy formed from at least two or more components. The coating alloy may be at least one of a lead-based, tin-based, and bismuth-based alloy. The coating may include a two-phase, three-phase, or more complex metal alloy. The coating may be formed of a metal alloy including at least one of Sn, Ag, Bi, Cd, Ga, In, Pb, Sn, Ti, and the like. The coating may also include a conductive material formed from metal or alloy particles embedded within an organic matrix.

[0039] The coating may be configured to substantially cover at least one, or each, of the first and second surfaces of at least one conductive element. The coating may be configured to substantially cover the first and second surfaces of each conductive element. For example, in embodiments where the conductive element comprises a third and / or fourth surface separating the first and second surfaces, at least one, or each, of the third and / or fourth surfaces may be at least partially coated with the coating. Each conductive element may be completely coated with the coating. In embodiments, the coating may be absent from a portion of the first and / or second surface. In embodiments, the coating may be absent from at least a portion of the third and / or fourth surface.

[0040] A first portion of the electrode assembly contacting the front side of the first solar cell may define a front connecting portion or connector of the electrode assembly, and a second portion of the electrode assembly contacting the back side of the second solar cell may define a back connecting portion or connector of the electrode assembly.

[0041] A first portion of each of the plurality of conductive elements may define a front connector of the electrode assembly. A second portion of each of the plurality of conductive elements may define a back connector of the electrode assembly. Thus, at least one, or each, of the plurality of conductive elements may extend from the front connector to the back connector of the electrode assembly.

[0042] The conductive element may be configured to bend along an axial direction of the conductive element to enable the electrode assembly to be coupled between the front and back surfaces of each of the first and second solar cells (i.e., to enable the conductive element to provide an electrical connection between the front and back connectors).

[0043] A first surface of the conductive element of the rear connector may be disposed to define a rear (i.e., rearmost) surface of the electrode assembly. A second surface of the conductive element of the front connector may be disposed to define a front (i.e., frontmost) surface of the electrode assembly.

[0044] Each of the conductive elements may have a width, an axial length, and a depth. Each of the conductive elements may be configured such that its axial length is substantially greater than its width and / or depth. The width and axial length of the conductive elements may be measured in a perpendicular direction aligned with the plane of the surface of the solar cell in which the conductive element is disposed (e.g., the front or back surface of the solar cell). The depth may be measured in a direction perpendicular to the same plane of the solar cell.

[0045] In an embodiment, the at least one conductive element may be configured such that its width is between 0.2mm and 0.4mm at its widest point. The length of the or each conductive element may depend on the length of the solar cell. In an exemplary form, the conductive element may be at least twice the length of the solar cell, optionally + / - 10mm. The depth (i.e. thickness) of the at least one or each conductive element may be between 0.2mm and 0.4mm. In an embodiment, the depth of the conductive element may be between 0.2mm and 0.4mm.

[0046] At least one or each of the plurality of conductive elements may be disposed within and / or on a film (e.g., a film portion). The film may be configured to be insulating and / or optically transparent. The film may be configured to provide adhesion between the solar cell and the conductive elements such that the conductive elements are properly spaced on the solar cell. In this manner, the film allows the conductive elements to be properly aligned with the solar cell. The film may provide a mechanical connection between the conductive elements and the solar cell. In an exemplary embodiment, the film may not cover all of the front and / or back sides of each of the solar cells.

[0047] The film may be configured such that at least a portion of at least one of the first and second surfaces of the at least one conductive element is exposed from the film to form an ohmic contact with the front and back surfaces of the first and second solar cells, respectively. For example, at least a portion of the first surface of the conductive element may be exposed from the film, and / or at least a portion of the second surface of the conductive element may be exposed from the film. In an embodiment, the film may be thinner than the at least one conductive element. For example, the conductive element may have a thickness (i.e., depth) of at least 0.2 mm to at most 0.4 mm, while the film may have a thickness of at least 0.07 mm to at most 0.12 mm.

[0048] As described above, the conductive elements of the front and back connectors may define a first and second portion of the plurality of conductive elements, respectively. The first portion of the plurality of conductive elements may be disposed in or on a first film (e.g., an insulating and / or optically transparent film). The second portion of the plurality of conductive elements may be disposed in or on a second film (e.g., an insulating and / or optically transparent film). Thus, the first surface may be exposed from the first film to form an ohmic contact with a front surface of the first solar cell, and / or the second surface may be exposed from the second film to form an ohmic contact with a back surface of the second solar cell.

[0049] A third portion of the plurality of conductive elements may be disposed between the first and second portions of the plurality of conductive elements. The third portion may be configured to be disposed between the first and second solar cells when the electrode assembly is connected therebetween. The third portion may be configured such that the conductive elements of this portion are not disposed within the film (i.e., in contrast to the first and second portions).

[0050] At least one, or each, of the conductive elements may be disposed on a surface of each of the first and second films. Alternatively, or in addition, at least one of the conductive elements may be at least partially disposed within the film. In this manner, at least one conductive element may be embedded within the film such that a surface of the conductive element protrudes beyond a surface of the film.

[0051] In use, the first film of the front connector may define a front film of the electrode assembly. Similarly, the second film of the back connector may define a back film of the electrode assembly. The front film may be configured to expose at least a portion of a first surface of the conductive element of the front connector. The back film may be configured to expose at least a portion of a second surface of the conductive element of the back connector.

[0052] The films (e.g., front and / or backing films) may be formed from polymeric materials having high ductility, good insulating properties, optical transparency and thermal stability, resistance to shrinkage. Exemplary polymeric materials may include acetate, epoxy, fluoroplastics, polyamide, polysulfone, rayon, polyolefin, plastyrene, rayonext, polyethylene terephthalate (PET), polyvinyl fluoride film, modified ethylene tetrafluoroethylene, and the like. In one embodiment, at least one of the first and second films is comprised of a single layer of material, while in some other embodiments, at least one of the first and second films has two or more layers, and two or more of these layers may comprise different materials and / or material properties.

[0053] The surface of the film facing the conductive elements may be coated with a transparent adhesive. During fabrication of the solar cell assembly, heat and / or pressure may be applied to the film to soften the adhesive, allowing for adhesion of the film to the conductive elements by application of force. In this manner, the wire may be at least partially embedded in the adhesive. In an embodiment, the conductive elements may be partially embedded in the adhesive but do not actually contact the film. The first and / or second films may be configured to structurally support the conductive elements prior to placement on the solar cell when multiple conductive elements are being handled.

[0054] When the front and back connectors are assembled with their respective first and second solar cells, the associated film may deform to conform to the shape of the conductive elements sandwiched between the film and the solar cells. In other words, the surface of the film may be substantially planar in the non-wire regions and may form ridges / protrusions above the conductive elements in the wire regions. In this way, each (e.g., longitudinal) conductive element contact region of the film may have a non-planar (e.g., transverse) profile.

[0055] The film of the front connector may have a back surface (i.e., facing toward the solar cells) and a front surface (i.e., facing away from the solar cells) opposite the back surface. At least one conductive element of a first portion of the plurality of conductive elements may be disposed on the back surface of the front film.

[0056] The back connector film may have a front surface (i.e., facing toward the solar cells) and a back surface opposite the front surface (i.e., facing away from the solar cells). At least one conductive element of the second portion of the plurality of conductive elements may be disposed on the front surface of the back film.

[0057] According to a second aspect of the present invention, there is provided a solar cell assembly comprising a first solar cell, a second solar cell, and an electrode assembly according to any one of the preceding statements. The plurality of conductive elements may be configured to electrically connect a front surface of the first solar cell with a back surface of the second solar cell.

[0058] Each of the first solar cell and the second solar cell may have a length, a width, and a depth. The length of the solar cell may be less than its width, and the depth may be less than both its width and length. The longitudinal and lateral directions across the front and back surfaces of the solar cell may be parallel to the length and width directions of the solar cell, respectively. Thus, the multiple conductive elements may be configured to extend across the length of the solar cell and be spaced apart along its width.

[0059] Each conductive element may be configured to extend longitudinally, vertically, relative to a surface of the solar cell on which it is overlaid. The conductive elements may be spaced laterally, relative to the solar cell surface, to define longitudinally extending spaces between the conductive elements. The conductive elements may be parallel to one another, or substantially parallel. The conductive elements may be laterally equally or substantially equally spaced. Thus, the plurality of conductive elements may form an array of parallel laterally spaced (e.g., equally spaced) conductive elements.

[0060] The electrode assembly may be configured to form an electrical connection with the conductive surfaces (or conductive portions of the surfaces) of the first solar cell and the second solar cell. As described above, the conductive elements of the electrode assembly are configured to optimize the optoelectronic properties of the front connector and / or back connector, such as their current collection and solar cell shading properties.

[0061] Each of the conductive surfaces of the solar cells may include a plurality of finger electrodes extending across the respective solar cell surface. The finger electrodes may be formed using a printing material that allows them to be easily deposited onto the surface of the solar cell.

[0062] Each finger electrode of the plurality of front finger and / or back finger electrodes may be configured to have an axial length that is substantially greater than its width. Both the width and axial length of the finger electrodes may be measured vertically in the plane of the respective surface of the solar cell. The finger electrodes may extend in a lateral direction parallel to the width direction of the solar cell.

[0063] The finger electrodes within each of the plurality of front and / or back finger electrodes may be spaced apart across a respective surface to define laterally extending spaces between the finger electrodes. The finger electrodes may be spaced apart in a longitudinal direction that is substantially parallel to a length of the solar cell. The finger electrodes of each of the plurality of finger electrodes may be substantially parallel to one another.

[0064] The axial length of at least one of the plurality of back finger electrodes may be substantially misaligned (e.g., may be substantially non-parallel or substantially perpendicular) with the axial length of at least one of the conductive elements of the electrode assembly overlaid thereon. Thus, the conductive element of the electrode assembly may be configured to extend across a surface of the solar cell and form an ohmic contact with each of the plurality of finger electrodes.

[0065] The axial length of the finger electrodes may be arranged substantially perpendicular to the axial length of the stacked conductive elements. In this manner, the conductive elements may be easily positioned to optimize charge collection from the surface of the solar cell. When a finger electrode is axially offset from the stacked conductive elements, the axial length of the associated finger electrode may be axially offset from each of the conductive elements at the same offset angle, or vice versa.

[0066] The solar cell of the solar cell assembly may comprise a number of layers, or elements, including a photovoltaic element, at least one of which is formed from a semiconductor material. The photovoltaic element (or layer) may be formed from a crystalline silicon wafer.

[0067] It is understood that the solar cell may be configured to define any type of solar cell structure. For example, the solar cell may define a heterojunction solar cell. Alternatively, the solar cell may define a tandem junction solar cell.

[0068] The surface of a solar cell may be textured to create a textured surface that corresponds to a non-uniform surface or has non-uniform characteristics, where the textured surface of the solar cell increases the amount of light incident on the solar cell, thereby improving the efficiency of the solar cell.

[0069] The solar cell may further comprise an anti-reflective layer or coating disposed on the front and / or back surface of the solar cell. The or each anti-reflective layer may have a single layer structure or a multi-layer structure. The anti-reflective layer may be formed from silicon nitride (SiNx) and / or silicon oxide (SiOx). Alternatively, the anti-reflective layer may be formed from a transparent conductive oxide (TCO), such as indium tin oxide (ITO), textured to have an anti-reflective surface. The anti-reflective layer effectively reduces the reflectance of light incident on the solar cell and increases the selectivity of a given wavelength band, thereby increasing the efficiency of the solar cell.

[0070] The solar cell may include a transparent conductive oxide coating disposed on a front and / or back surface of the solar cell, the transparent conductive oxide coating may be configured to increase lateral carrier transport to finger electrodes disposed on each surface of the solar cell.

[0071] According to an exemplary embodiment, the conductive element may at least partially form an electrode assembly that is applied to the first solar cell and the second solar cell to define a solar cell assembly. Further, one or more solar cell assemblies according to the present invention may be electrically connected and disposed within a housing to define a solar module.

[0072] According to an exemplary embodiment, a second electrode assembly may be provided to couple the front surface of the second solar cell to the back surface of the third solar cell. The conductive elements in the second electrode assembly may be as described above for the first electrode assembly. In this situation, the second and third solar cells may be combined with the second electrode assembly to define a second solar cell assembly. The conductive elements of the back connector of the first electrode assembly may be aligned with the conductive elements of the front connector of the second electrode assembly, with the second solar cell interposed therebetween.

[0073] The solar module may include a frame for housing the plurality of solar cell assemblies. The frame may include a front plate and a back plate disposed on the front and back sides of the plurality of solar cell assemblies, respectively. At least one or each of the front plate and the back plate may be formed from glass (e.g., a glass sheet). The solar module may include an encapsulant configured to bond between the front plate and the back plate and the plurality of solar cell assemblies. 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 assemblies. The encapsulant may also be disposed between the back sheet of the solar module and an insulating optically transparent film of one of the plurality of solar cell assemblies. The encapsulant may be configured to prevent the ingress of moisture into the solar module. Thus, the encapsulant may be formed from ethylene vinyl acetate (EVA), or any other suitably moisture resistant material.

[0074] According to a third aspect of the present invention, there is provided a method of manufacturing a solar cell assembly according to any one of the preceding statements. The method may include arranging a second solar cell such that its back surface faces substantially upward. The method may further include overlaying a first section of the electrode assembly onto a back surface of the second solar cell such that a second surface of the at least one conductive element is arranged in contact with the back surface. The method may further include connecting (e.g., electrically and / or mechanically) the second surface of the at least one conductive element onto the back surface of the second solar cell. The method may include overlaying a front surface of the first solar cell onto the second section of the electrode assembly such that a first surface of the at least one conductive element is arranged in contact with the front surface. The method may further include connecting (e.g., electrically and / or mechanically) the first surface of the at least one conductive element onto the front surface of the first solar cell.

[0075] As mentioned above, the present invention is particularly beneficial during the process of manufacturing a solar cell assembly (i.e., when bonding the electrode assembly to the first solar cell and the second solar cell). This is because, when the solar cell is inverted during the connection step, the smaller contact area of ​​the second surface causes the coating to flow toward the contact surface (i.e., back surface) of the second solar cell due to gravity. Furthermore, the larger contact area defined by the first surface can retain the coating on the contact surface (i.e., front surface) of the first solar cell despite being inverted.

[0076] As described above, each solar cell has a back surface (e.g., a back surface) and a front surface (e.g., a front surface) opposite the back surface. Thus, the method may include disposing a portion of the electrode assembly on the back surface of the second solar cell to define a back connector. The method may further include disposing another portion of the electrode assembly on the front surface of the first solar cell to define a front connector.

[0077] The method may include applying heat and / or pressure (e.g., soldering) to a first portion of the conductive element (i.e., at the front connector) to melt at least a portion of the coating. The portion of the molten coating disposed on the first surface of the conductive element (i.e., the surface facing the front of the first solar cell) may be configured to form an ohmic contact with a conductive surface (e.g., a finger electrode) of the first solar cell over which the conductive element is overlaid.

[0078] The method may include applying heat and / or pressure (e.g., soldering) to a second portion of the conductive element (i.e., at the back connector) to melt at least a portion of the coating. The portion of the molten coating disposed on the second surface of the conductive element (i.e., the surface facing the back side of the second solar cell) may be configured to form an ohmic contact with a conductive surface (e.g., a finger electrode) of the second solar cell over which the conductive element is overlaid.

[0079] The conductive element coating may be made of a material having a lower melting point than the material from which the conductive element is formed. The conductive element coatings of the front and back connectors may be connected to the respective surfaces of the first and second solar cells separately or during the same process.

[0080] The method may include first attaching one of the front connector and the back connector to each of the first solar cell and the second solar cell, and then attaching the other of the front connector and the back connector to the other of the first solar cell and the second solar cell.

[0081] In situations where the electrode assembly comprises a film (e.g., an insulating and / or optically transparent film), the method may further include attaching the film to the conductive element (e.g., forming the electrode assembly according to an exemplary embodiment). The method may include attaching the film to the conductive element before overlaying and / or attaching the conductive element to the solar cell. The method may include applying heat and / or pressure to the film (e.g., laminating) to adhere the film to the conductive element.

[0082] The method of attaching the film to the conductive element may be performed during a method of bonding an associated conductive element to a surface of the solar cell. Thus, the method of attaching the film to the conductive element (e.g., applying heat and / or pressure to the film) may also include attaching the film to the associated surface of the solar cell.

[0083] In situations where a first portion of the plurality of conductive elements is disposed on a first film portion (e.g., a first connector) and / or a second portion of the plurality of conductive elements is disposed on a second film portion (e.g., a second connector), the first and / or second film portions may be attached to the respective first and / or second portions of the conductive elements.

[0084] The method may further include disposing (e.g., depositing) a plurality of finger electrodes on at least one or each of the front and back surfaces of the first solar cell and the second solar cell. It is understood that the method of disposing the finger electrodes may be performed before connecting the electrode assembly to the solar cell. The finger electrodes may be formed using a printing material that allows it to be easily deposited on the surface of the solar cell. The printing material may be formed using a printable precursor such as a conductive paste that may include 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 the printed finger electrodes. Alternatively, the finger electrodes may be deposited by a variety of other methods including evaporation, plating, printing, and the like. The front finger electrodes and the back finger electrodes may be deposited simultaneously (i.e., using a single deposition process) or they may be deposited separately.

[0085] Those skilled in the art will appreciate that, unless mutually exclusive, a feature or parameter described in connection with any one of the above aspects may be applied to any other aspect. Further, unless mutually exclusive, any feature or parameter described herein may be applied to any aspect and / or may be combined with any other feature or parameter described herein. [Brief description of the drawings]

[0086] Embodiments will now be described, by way of example only, with reference to the drawings in which:

[0087] [Figure 1] 1 is an enlarged cross-sectional side view of a solar module having a solar cell assembly, the solar cell assembly comprising a first solar cell coupled to a second solar cell by an electrode assembly. [Figure 2A] 2 is a plan view of the top (front) and bottom (back) surfaces of the first solar cell shown in FIG. 1. FIG. [Figure 2B]FIG. 2B is a transverse cross-sectional view of the first solar cell shown in FIG. 2A. [Figure 2C] 2 is a plan view of the top (front) and bottom (rear) surfaces of the second solar cell shown in FIG. 1. FIG. [Figure 2D] FIG. 2D is a transverse cross-sectional view of the second solar cell shown in FIG. 2C. [Figure 3A] FIG. 2E is an enlarged cross-sectional view of the first solar cell shown in FIGS. 2A to 2D. [Figure 3B] FIG. 2E is an enlarged cross-sectional view of the second solar cell shown in FIGS. 2A to 2D. [Figure 4] 2 is a cross-sectional view of an alternative conductive element suitable for use in the electrode assembly shown in FIG. 1. [Diagram 5] 2 is a cross-sectional view of an alternative conductive element suitable for use in the electrode assembly shown in FIG. 1. [Figure 6] 2 is a cross-sectional view of an alternative conductive element suitable for use in the electrode assembly shown in FIG. 1. [Figure 7] 2 is a cross-sectional view of an alternative conductive element suitable for use in the electrode assembly shown in FIG. 1. [Figure 8] 2 is a cross-sectional view of an alternative conductive element suitable for use in the electrode assembly shown in FIG. 1. [Figure 9] 2 is a cross-sectional view of an alternative conductive element suitable for use in the electrode assembly shown in FIG. 1. [Figure 10A] 1A-1D are side views of a solar cell assembly illustrating different stages of a method for manufacturing the assembly. [Figure 10B] 10B-10C are cross-sectional views of a solar cell of the solar cell assembly shown in FIG. 10A illustrating different stages of a manufacturing method. [Figure 11A] 1A-1D are side views of a solar cell assembly illustrating different stages of a method for manufacturing the assembly. [Figure 11B] 11B-11C are cross-sectional views of a solar cell of the solar cell assembly shown in FIG. 11A, illustrating different stages of a manufacturing method. [Figure 12A] 1A-1D are side views of a solar cell assembly illustrating different stages of a method for manufacturing the assembly. [Figure 12B]12B-12C are cross-sectional views of a solar cell of the solar cell assembly shown in FIG. 12A, illustrating different stages of a manufacturing method. [Figure 13A] 1A-1D are side views of a solar cell assembly illustrating different stages of a method for manufacturing the assembly. [Figure 13B] 13B-13C are cross-sectional views of a solar cell of the solar cell assembly shown in FIG. 13A, illustrating different stages of a manufacturing method. [Figure 14A] 1A-1D are side views of a solar cell assembly illustrating different stages of a method for manufacturing the assembly. [Figure 14B] 14B-14C are cross-sectional views of a solar cell of the solar cell assembly shown in FIG. 14A illustrating different stages of a manufacturing method. [Figure 15A] 1A-1D are side views of a solar cell assembly illustrating different stages of a method for manufacturing the assembly. [Figure 15B] 15B-15C are cross-sectional views of a solar cell of the solar cell assembly shown in FIG. 15A illustrating different stages of a manufacturing method. [Figure 16] 15C is a flow chart illustrating a method of manufacturing the solar cell assembly shown in FIGS. 15A and 15B. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0088] Aspects and embodiments of the present disclosure will now be described with reference to the accompanying drawings, and further aspects and embodiments will be apparent to those skilled in the art.

[0089] In the drawings, the thicknesses of layers, films, elements, etc. have been exaggerated for clarity. Furthermore, when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it is understood that it may be directly on the other element or that intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present.

[0090] 1 shows a solar cell assembly 10 according to the present invention, disposed within a support assembly 102 of a solar module 100 (e.g., a solar panel). The solar cell assembly 10 includes a first solar cell 20, a second solar cell 30, and an electrode assembly 12 disposed to electrically connect a front surface 22 of the first solar cell 20 to a back surface 34 of the second solar cell 30.

[0091] The electrode assembly 12 also includes a plurality of conductive elements that are configured to provide an improved electrical path between the first solar cell 20 and the second solar cell 30 while simultaneously enhancing light scattering and absorption conditions at the front surface 22 of the first solar cell 20.

[0092] A first portion of the electrode assembly 12 is positioned to contact the front surface 22 of the first solar cell 20 to define a front connection portion or front connector 12a of the electrode assembly 12. A second portion of the electrode assembly 12 contacts the back surface 34 of the second solar cell 30 to define a back connection portion or back connector 12b of the electrode assembly 12. The first connector 12a and the second connector 12b are electrically connected by a third interconnect portion 12c that bends between the top surface 22 and the bottom surface 34 of each of the adjacently positioned solar cells 20, 30 of the solar cell assembly 10.

[0093] The solar cell assembly 10 is one of a plurality of solar cell assemblies arranged within a support assembly 102. For example, the front surface 32 of the second solar cell 30 is electrically connected to the back surface of a third solar cell (not shown) by a second electrode assembly 14. Also, a third electrode assembly 16 is provided to couple the back surface 24 of the first solar cell 20 to the front surface of a fourth solar cell (not shown).

[0094] For example, it will be understood that the second and third solar cells in this arrangement are electrically connected by the second electrode assembly 14 to define a second solar cell assembly, whereby the multiple solar cells 20, 30 are connected by the electrode assemblies 12, 14, 16 to define a single string.

[0095] The front plate 104 of the support assembly 102 comprises a transparent (e.g., glass) sheet configured to allow light to pass through to a central chamber 106 in which the solar cell assemblies 10 rest. The arrows at the top of Figure 1 indicate the direction of solar radiation incident on the solar cell assemblies 10.

[0096] A back plate 108 of the support assembly 102 is positioned to enclose the solar cell assembly 10 within a central chamber 106. The back plate 108 includes a reflective sheet configured to reflect any light incident on its top surface toward the solar cell assembly 10. The central chamber 106 is filled with an encapsulant material (shaded area shown in FIG. 1 ) that prevents external liquids from entering or gases from entering.

[0097] Figures 2A and 2C show top (front) and bottom (back) views, respectively, of a first solar cell 20 and a second solar cell 30 of the solar cell assembly 10. Figures 2B and 2D show transverse cross-sectional views of the first solar cell 20 and the second solar cell 30 along dashed lines AA and BB, respectively, as shown in Figures 2A and 2C.

[0098] Each of the solar cells 20, 30 has a length, which is the vertical dimension in Figures 2A and 2C, and a width, which is the horizontal dimension in Figures 2A and 2C. The first solar cell 20 and the second solar cell 30 are arranged in a common cross-section (as shown in Figure 1) with their width and length dimensions parallel to one another. The front surface 22, 32 of each solar cell defines a surface onto which light is incident when the solar cell assembly 10 is in use. The back surface 24, 34 defines a surface opposite the respective front surface 22, 32, as shown in Figures 2B, 2D.

[0099] Each solar cell 20, 30 has a layered structure (not shown) disposed between its respective front and back surfaces. The layered structure is a multi-layer semiconductor assembly including photovoltaic elements (or layers) configured to generate charge carriers from the absorption of incident radiation. The front and back finger electrodes 26, 36, 28, 38, respectively, are configured to conduct the charge carriers generated by the respective solar cell 20, 30.

[0100] The first solar cell 20 includes a first plurality of finger electrodes 26 (i.e., front finger electrodes) disposed on its front surface 22 and a second plurality of finger electrodes 28 (i.e., back finger electrodes) disposed on its back surface 24. Similarly, the second solar cell 30 includes a first plurality of finger electrodes 36 disposed on its front surface 32 and a second plurality of finger electrodes 38 disposed on its back surface 34.

[0101] The electrode assembly 12 includes a plurality of conductive elements 18, as shown in Figures 2A-2D. The conductive elements are configured to form ohmic contacts with finger electrodes 26, 38 disposed on the front surface 22 and back surface 34 of the first solar cell and the second solar cell, respectively. Each of the conductive elements 18 has an integral elongated form, such as a wire, formed from a conductive material. For example, the conductive elements 18 include a metal alloy material including at least one of Ag, Al, Au, and Cu. Each of the conductive elements 18 is disposed within an optically transparent insulating film 40, as shown most clearly in Figures 2B and 2D.

[0102] A first portion 18a of the plurality of conductive elements 18 defines a front connector 12a of the electrode assembly 12. A second portion 18b of the plurality of conductive elements 18 defines a back connector 12b of the electrode assembly 12. Thus, each of the plurality of conductive elements 18 extends from the front connector 12a to the back connector 12b of the electrode assembly 12. A third portion 18c of the plurality of conductive elements 18 is configured to electrically connect the respective first and second portions 12a, 12b.

[0103] The conductive element 18 is configured to bend along an axial direction of the conductive element 18 at the third portion 18a to enable the electrode assembly 12 to form an electrical connection between the front connector 12a and the back connector 12b.

[0104] As described above, the conductive elements 32 are formed from a conductive material such that they are configured to allow charge carriers to flow between the conductive elements 18 and the finger electrodes 26, 38 on the front and back surfaces 22, 34 of the first and second solar cells 20, 30. In this manner, each of the conductive elements 18 defines a current collector of the electrode assembly 12. Additionally, the conductive elements 18 are configured to collect and transfer charge carriers from the front finger electrodes 26 of the first solar cell 20 to the back finger electrodes 38 of the second solar cell 30, or vice versa.

[0105] Each of the conductive elements 18 has a width, a length, and a depth. The length of each conductive element 18 defines an axial length that is substantially greater than its width and depth. The conductive elements 18 are configured with an asymmetric cross-section, which improves the electrical connection between the conductive elements 18 and the finger electrodes 26, 38 on the surface of the solar cell, as described in more detail below.

[0106] The respective arrangements of the plurality of finger electrodes 26, 28, 36, 38 and conductive element 18 will now be described in more detail with reference to Figures 2A-2D.

[0107] A plurality of front finger electrodes and back finger electrodes 26, 28, 36, 38 are arranged to extend laterally (horizontally in Figures 2A and 2C) across the solar cells 20, 30 and are equally spaced apart longitudinally (vertically in Figures 2A and 2C).

[0108] The dimensions of each finger electrode 26, 28, 36, 38 are substantially the same as the dimensions of every other finger electrode 26, 28, 36, 38. For example, the finger electrodes have a common length, width, and depth such that each electrode is positioned so that it protrudes the same amount from the surface of the solar cell. Additionally, each of the finger electrodes has a rectangular cross-section (measured perpendicular to the length of the electrode).

[0109] The finger electrodes disposed on the front 26, 36 and back 28, 38 of the solar cells 20, 30, respectively, are aligned parallel to each other and to the corresponding finger electrodes on the opposite side of the solar cell. For example, each one of the finger electrodes 26 disposed on the front 22 of the first solar cell 20 is aligned longitudinally with a corresponding finger electrode 28 from the plurality of back finger electrodes 28. As shown in Figures 2A and 2C, each of the plurality of front and back finger electrodes 26, 28, 36, 38 comprises 12 finger electrodes. However, it should be understood that in some other embodiments, the number of front and back finger electrodes 26, 28, 36, 38 may be different without departing from the scope of the present invention.

[0110] The number of conductive elements 18 in the electrode assembly 12 is between 4 and 20. According to embodiments described herein, the first electrode assembly 12 has between 14 and 18 conductive elements 18, for example, 16 conductive elements 18 as shown in Figures 2A-2D. However, it is understood that in some other embodiments, a different number of conductive elements may be present without departing from the scope of the present invention.

[0111] First and second portions 18a, 18b of the plurality of conductive elements 18 are parallel to and extend longitudinally relative to the front and back surfaces 22, 34 of the solar cell in a longitudinal direction (vertical in FIG. 2A). The conductive elements 18 are also equally spaced laterally relative to the front and back surfaces 22, 34 (horizontal in FIG. 2A) so as to define longitudinally extending spaces between the conductive elements 18. Each one of the first and second portions 18a, 18b thus defines an array of parallel, laterally spaced conductive elements 18.

[0112] Each of the first portions 18a of the multiple conductive elements 18 is axially aligned with a corresponding second portion 18b of the conductive element 18 of the same electrode assembly 12. Also, the second portion 18b of the conductive element 18 of the first electrode assembly 12 is axially aligned with the first portion 18a of the conductive element 18 of the second electrode assembly 14, with the second solar cell 30 therebetween.

[0113] According to the above-described arrangement, it will be understood that the plurality of front finger electrodes 26 and rear finger electrodes 38 are arranged perpendicular to the first portion 18a and second portion 18b of the plurality of conductive elements 18, as shown in Figures 2A and 2C.

[0114] The finger electrodes 26, 28, 36, 38 are formed from a conductive material, which is formed from a metal alloy including Ag. The conductive material is a printable material that allows the finger electrodes to be easily deposited onto the respective surfaces of the solar cells. The printable material is formed using a printable precursor, such as a conductive paste, which includes a mixture of silver metal powder and glass frit suspended in a solvent. The conductive paste may be fired or cured to form the finger electrodes.

[0115] As described above, the electrode assembly 12 includes an insulating, optically transparent film 40 on which the conductive elements 18 are disposed. The first and second portions 18a, 18b of the plurality of conductive elements 18 are disposed on separate film portions disposed on the front and back surfaces 22, 34 of the respective solar cells. For example, the front connector 12a includes a first film portion defining a front film portion 42, and the back connector 12b includes a second film portion defining a back film portion 44. However, it should be noted that the conductive elements 18 in the third portion 18c are not covered by either film.

[0116] According to an exemplary configuration of the solar cell assembly 10, each of the first and second portions 18a, 18b of the conductive element 18 is attached to a surface of its respective film 42, 44 that faces the solar cell. This "solar cell facing" surface of each film 42, 44 is coated with an adhesive that adheres the conductive element to the respective film 42, 44.

[0117] 2B and 2D, for front connector 12a, film 42 is positioned to contact front surface 22 of the solar cell in the area between conductive element 18 and front finger electrode 26. Back film portion 44 is configured in the same manner for back connector 12b.

[0118] In an exemplary configuration of the solar cell assembly 10, each of the films 42, 44 is configured to at least partially (e.g., completely) surround or encircle a respective conductive element 18 and a respective finger electrode 26, 38, as shown in Figures 2B and 2D.

[0119] The front film portion 42 and the back film portion 44 are positioned to provide adhesion between the solar cell and the conductive element 18 such that the conductive element is properly positioned on the solar cell (i.e., aligned with the finger electrodes). In an exemplary embodiment, the front film portion 42 and the back film portion 44 may not completely cover the respective surfaces of the solar cell.

[0120] On the other hand, the front film portion 42 and the back film portion 44 shown in the drawings have substantially flat bottom and top surfaces, respectively. It is understood that the film may be configured to conform to the structural components of the solar cells and / or conductive elements. For example, the film 40 of the back connector 12b may conform to the finger electrodes 38 and conductive elements 18 disposed on the back surface 34 of the solar cells 30. According to this exemplary embodiment, the film 40 may consist of elongated channels recessed towards the solar cells in the areas between the conductive elements of the back surface 34, or may form ridges / protrusions on the structural electrodes (e.g., finger electrodes and conductive elements), if present.

[0121] Front film portion 42 and back film portion 44 are applied with heat and pressure onto each surface of the solar cell such that the films conform to the finger electrodes and conductive elements disposed thereon.

[0122] According to an alternative exemplary embodiment, films 40 may have channels disposed on their respective solar cell-facing surfaces. The channels may be configured to fit closely around corresponding conductive elements and finger electrodes.

[0123] The front film portion 42 and the back film portion 44 may be thinner than the conductive element 18. For example, the conductive element 18 may have a thickness (i.e., depth) of at least 200 μm and at most 400 μm (e.g., 0.2 mm to 0.4 mm), while the film may have a thickness of at least 70 μm and at most 120 μm (e.g., 0.07 mm to 0.12 mm).

[0124] The front film portion 42 and the back film portion 44 are each formed from a polymeric material having high ductility, good insulating properties, optical clarity, and thermal stability and resistance to shrinkage. An exemplary polymeric material is modified ethylene tetrafluoroethylene.

[0125] The configuration of conductive element 18 will now be described in more detail with reference to Figures 3A, 3B, and 4-9. In an exemplary form, conductive element 18 has a circular cross-sectional shape (i.e., transverse to the axial length of conductive element 18) as shown in Figures 3A, 3B, 4, and 7, respectively. However, conductive element 18 may be configured to have different cross-sectional shapes, as shown in Figures 5, 6, 8, and 9, without departing from the scope of the present invention.

[0126] Each of the conductive elements 18 includes a first surface 50 configured to make electrical contact with the front surface 22 of the first solar cell 20, as shown in Figure 3A. Each conductive element 18 also includes a second surface 54 configured to make electrical contact with the back surface 34 of the second solar cell 30, as shown in Figure 3B.

[0127] At least a portion of each of the first surface 50 and second surface 52 is provided with a coating 60 that is configured, during use, to solder the respective first surface 50 and second surface 52 to the surface of the solar cell 20, 30 on which they are overlaid.

[0128] It will be understood that FIG. 3A shows a first portion 18a of the conductive element 18 (i.e., the front connector 12a of the electrode assembly 12) on the front side 22 of the first solar cell 20, while FIG. 3B shows a second portion 18b of the same conductive element 18 (i.e., the back connector 12b of the electrode assembly 12) on the back side 34 of the second solar cell 30.

[0129] The first surface 50 and the second surface 52 define two distinct longitudinal surfaces (i.e., surfaces extending in the longitudinal direction of the conductive element) of the conductive element 18. In particular, the first surface 50 and the second surface 52 define an upper or lower surface of the conductive element 18. As such, the first surface 50 is disposed opposite the second surface 52 of the conductive element 18.

[0130] Each of the conductive elements 18 includes a substantially flat first surface 50. The first surface 50 of the conductive element portion 18a is configured to have a plane that faces and lies parallel to the front surface 22 of the first solar cell 20, as shown in FIG. 3A. The flat first surface 50 is particularly advantageous in situations where the solar cells are inverted during their connection to the electrode assembly 12. In such situations, the first surface 50 of the conductive element 18 is arranged to face substantially upward (e.g., vertically upward), as described in more detail below. When heat and / or pressure are applied to the conductive element 18 (e.g., lamination) to form a connection with the solar cell front surface 22, the coating 60 is supported on the flat surface, thereby preventing it from flowing away from the contact interface with the solar cell surface due to gravity.

[0131] In contrast to the first surface 50, the second surface 52 of the conductive element is substantially curved, as shown in Figure 3B. The convex shape of the second surface 52 defines a cross-sectional arc whose ends terminate at the ends of the first surface 50. In this manner, each of the conductive elements 18 comprises a semi-elliptical cross-section, as shown in Figures 3A and 3B.

[0132] The contact area of ​​the first surface 50 is defined by the width of the first surface 50 that forms electrical contact with the front surface 22 (e.g., front finger electrode 36) of the first solar cell 20. Thus, the contact area of ​​the first surface 50 is substantially defined by the width of the coating 60 formed between the first surface 50 and the front surface 22 of the solar cell, as shown in FIG.

[0133] The contact area of ​​the second surface 52 is defined by the width of the second surface 52 that forms electrical contact with the back surface 34 (e.g., back finger electrode 38) of the second solar cell 30. In particular, the contact area of ​​the second surface 52 is defined by the width of the coating 60 that is formed between the second surface 52 and the back surface 34 of the solar cell, as shown in FIG. 3B. Thus, because the first surface 50 has a wider cross-sectional width (i.e., contact width) than the second surface 52, the contact width of the first surface 50 is also larger than the contact area defined by the second surface 52.

[0134] The curved configuration of second surface 52 causes coating 60 to flow toward the top center point of second surface 52. This arrangement of second surface 52 also causes coating 60 to wet onto the back surface 34 of second solar cell 30, narrowing the width of the contact area between conductive element 18 and second solar cell 30. Considering front connector 12a, curved second surface 52 also has a light scattering surface on the front surface 22 of first solar cell 20, as indicated by the dashed arrow in FIG. 3A.

[0135] It will be understood that the first and second contact areas are also defined, at least in part, by the length of each conductive element 18 (i.e., the length of the first conductive element portion 18a and the second conductive element portion 18b associated with the front connector 12a and the back connector 12b, respectively) that is configured to overlap the front surface 22 and the back surface 34 of the first solar cell 20 and the second solar cell 30, respectively.

[0136] The electrode assembly 12 is configured such that the length of the portion 18a of the conductive element 18 that overlaps the front surface 22 of the first solar cell 20 is equal to the length of the conductive element portion 18b that overlaps the back surface 34 of the second solar cell 30. The difference in the respective contact areas is thus defined by the contact width of each of the first and second surfaces 50, 52 of the conductive element 18.

[0137] According to an exemplary embodiment, the conductive element 18 may include a third surface 54 and a fourth surface 56 disposed between the first surface 50 and the second surface 52, as shown in Figures 5, 6, 8, and 9. The fourth surface 56 is disposed opposite the third surface 54, and they each space the first surface 50 from the second surface 52 to define a depth of the conductive element 18.

[0138] According to each of these exemplary configurations, the second surface 52 is configured to be substantially flat. The flat second surface 52 is disposed parallel to the first surface 50 and the front surface 22 and back surface 34 of each of the first solar cell 20 and the second solar cell 30. Compared to a curved second surface, the flat second surface 52, when disposed in front of the first solar cell 20, provides more robust electrical contact with the second solar cell 30 while still scattering some light.

[0139] The third surface 54 and the fourth surface 56 may be configured to have a convex curve, as shown in Figures 5 and 7. In these arrangements, the conductive element 18 has a cross-sectional shape that defines a truncated semicircle. Alternatively, as shown in Figures 6 and 9, the third surface 54 and the fourth surface 56 may be substantially flat, such that the cross-section of the conductive element defines a truncated triangle.

[0140] The conductive elements 18 are each configured to have an asymmetric cross-sectional shape about a central lateral plane CL of the conductive element 18, as shown by the dashed horizontal line in Figures 4-6. The central lateral plane CL defines a plane extending widthwise or horizontally through the longitudinal axis of the conductive element 18. The conductive elements 18 are also configured to have a symmetric cross-sectional shape about a central vertical plane CV of the conductive element 18. The central vertical plane CV defines a plane extending depthwise or vertically through the longitudinal axis of the conductive element 18, as shown by the vertical dashed line in Figures 4-6.

[0141] In each of the exemplary configurations shown in Figures 4-9, the coating 60 is configured to substantially cover the first surface 50 and the second surface 52. As shown in Figure 4, the coating 60 is disposed to cover only the portion of the second surface 52 that is configured to contact a solar cell surface (e.g., the back surface 34 of the second solar cell 30). In an exemplary configuration in which the conductive element 18 has a third surface 54 and a fourth surface 56, as shown in Figures 5 and 6, the coating 60 is disposed only on the first surface 50 and the second surface 52. Alternatively, as shown in Figures 7-9, each of the surfaces of the conductive element may be coated with the coating 60.

[0142] Coating 60 is a conductive material having a melting point lower than the melting point of conductive element 18. Coating 60 comprises a metal alloy formed from at least two or more components, such as lead-based, tin-based, and bismuth-based alloys. Alternatively, coating 60 may comprise two-phase, three-phase, or more complex metal alloys, as will be understood by those skilled in the art.

[0143] In the exemplary configurations shown in Figures 3A, 3B, and 4-9, each conductive element 18 is configured to have a constant cross-section along its length. Each conductive element 18 is positioned such that the first surface 50 and the second surface 52 maintain their respective positions on the conductive element 18 as the element extends and connects between the first solar cell 20 and the second solar cell 30. In this manner, each conductive element 18 is configured to be free of any axial twists or kinks along its length.

[0144] Each of the conductive elements 18 is formed from a single wire section (i.e., the first portion 18a and the second portion 18b of each conductive element 18 are integrally formed with one another). In this manner, the conductive elements 18 provide a direct electrical connection between the first solar cell 20 and the second solar cell 30, enhancing the flow of electrical current therebetween. Configuring the conductive elements in this manner eliminates the need for separate connections (such as copper ribbons) between adjacent solar cells, thereby reducing the number and complexity of manufacturing steps required to fabricate the solar cell assembly 10.

[0145] An exemplary method of manufacturing the solar cell assembly 10 will now be described with reference to Figures 10A-15B, which illustrate the steps of the manufacturing method, and Figure 16, which illustrates a flow chart of the corresponding method steps.

[0146] The method begins with a first step 202 in which a first solar cell 20, a second solar cell 30, and an electrode assembly 12 are provided, as described above. Prior to the first step 202, the solar cells are manufactured in a conventional manner, as will be understood by those skilled in the art. In particular, the method includes configuring each of the solar cells with a conductive surface (or conductive portion) on the front and back surfaces of each of the solar cells. For example, this can be accomplished through deposition of conductive material on the front and back surfaces 22, 34 of the first and second solar cells 20, 30 to form a plurality of front and back finger electrodes 36, 38, respectively.

[0147] According to an exemplary method, the finger electrodes 36, 38 are deposited on their respective surfaces using a screen printing process. The screen printing process involves applying a printable precursor onto the layered structure surface through a screen or mask. The printable precursor comprises a metal paste obtained by mixing a metal powder with a glass frit in the presence of a suitable solvent. The openings in the mask determine the placement and dimensions of each of the printed features (i.e., the finger electrodes). Once the printable precursor is provided on the solar cell surface, it is then fired in a furnace to form the corresponding finger electrodes.

[0148] The electrode assembly 12 may be formed by disposing first and second portions of the films 42 , 44 , respectively, and the plurality of conductive elements 18 to define the front connector 12 a and the back connector 12 b of the electrode assembly 12 .

[0149] Once the multiple finger electrodes 36, 38 are deposited on the surfaces of the first solar cell 20 and the second solar cell 30, the electrode assembly 12 can be connected to the solar cells 20, 30 to define the solar assembly 10 of the present invention.

[0150] In step 204, the second solar cell 30 is positioned with its back surface 34 facing upwards, for example as shown in Figures 10A and 10B. Once the second solar cell 30 is flipped over, then in step 206, the back connector 12b of the electrode assembly 12 is superimposed on the back surface 34 of the second solar cell 30. Thus, as shown in Figure 11B, the conductive elements 18 are superimposed on the back surface 34 such that they lie perpendicular to the finger electrodes 38. As a result of method step 206, the second surfaces 52 of the conductive elements 18 come into contact with the back finger electrodes 34 of the solar cell.

[0151] In step 208, the second surfaces 52 of the plurality of conductive elements 18 are connected to the back surface 34 of the second solar cell 30. This method step includes heating and / or applying pressure to the conductive elements 18 in the second connector 12b to bond the coating 60 under compressive force to the back surface 34 of the second solar cell, as shown in FIG.

[0152] The application of heat and pressure causes the coating 60 on the second surface 52 of the conductive element 18 to flow due to gravity toward the back surface 34 of the second solar cell 30. The coating 60 wets to the solar cell surface, and the curvature of the second surface 52 of the conductive element causes the coating 60 to accumulate or pool at the interface between the solar cell and the conductive element.

[0153] As the coating cools and solidifies, it forms an ohmic contact with the underlying back finger electrode 38, as shown in Figure 12B. The application of heat and pressure also laminates a backing film 44 onto the back surface 34 of the solar cell 30.

[0154] The method proceeds to step 210 where the first solar cell 20 is inverted and stacked onto the front connector 12a, as shown in Figures 10A and 10B, such that the first surface 50 of the front portion 18a of the conductive element is brought into contact with the front surface 22 of the first solar cell 20.

[0155] In step 212, the first surfaces 50 of the plurality of conductive elements 18 are then connected to the front surface 22 of the first solar cell 20. Similar to step 208, the method includes heating and / or applying pressure to the conductive elements 18 of the front connector 12a to physically bond them to the front surface 22 of the first solar cell under compressive force, as shown in FIG. 14B. The application of heat and pressure melts the coating 60 on the first surfaces 50 of the conductive elements and then wets against the front surface 22 of the first solar cell. The planar first surface 50 is configured to hold the molten coating 60 in place at the interface with the solar cell 20 while the coating 60 cools and solidifies to form an ohmic contact therebetween. The application of heat and pressure also laminates the front film 42 onto the front surface 22 of the first solar cell, as shown in FIG. 15B.

[0156] In an embodiment, the front plate 104 of the solar module 100 is formed of glass and the back plate 108 is formed of a lighter polymer sheet. In this case, an additional advantage of assembling the solar cell assembly 10 with inverted solar cells 20, 30 is that it is easier to build the solar assembly 10 on the heavier front plate 104 and then cover it with the lighter back plate 108. This reduces the risk of damaging the solar module 100 compared to having to place the heavier glass front plate 104 in place on top of a pre-assembled solar assembly 10.

[0157] It is understood that at least some of the above method steps can be performed simultaneously or in any order. For example, the method steps including placing the first solar cell 20 and the second solar cell 30 inverted relative to the electrode assembly 12 can be performed substantially simultaneously. Similarly, the front connector 12a and the back connector 12b may also be connected simultaneously to the front surface 22 and the back surface 34 of the first solar cell 20 and the second solar cell 30, respectively.

[0158] As a result of the above-described method, the front connector 12a and the back connector 12b of the electrode assembly 12 are both mechanically and electrically connected to the respective first solar cell 20 and second solar cell 30 to form the solar cell assembly 10 according to the present invention.

[0159] It is understood that the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the concept described herein. Any feature can be used separately or in combination with any other feature, except where mutually exclusive, and the present disclosure extends to and includes all combinations and subcombinations of one or more features described herein.

[0160] Feature List Solar cell assembly 10 Electrode assemblies 12, 14, 16 Front connector 12a Back connector 12b Interconnection part 12c Conductive element 18 A first portion of the conductive element 18a A second portion of the conductive element 18b A third portion of the conductive element 18c First solar cell 20 Front 22 back side 24 Front Finger Electrode 26 Back finger electrode 28 Second solar cell 30 front 32 back side 34 Front Finger Electrode 36 Back finger electrode 38 Film 40 Front film part 42 Back film part 44 Conductive Element - First Surface 50 Conductive Element - Second Surface 52 Conductive Element-Third Surface 54 Conductive Element-Fourth Surface 56 Coating 60 Solar Module 100 Support Assembly 102 Front panel 104 Central Chamber 106 Back plate 108 Method steps 200-212

Claims

1. 1. An electrode assembly for connecting a front surface of a first solar cell to a back surface of a second solar cell, comprising: a plurality of conductive elements, at least one of the conductive elements comprising: a first surface for contacting the front surface of the first solar cell; a second surface for contacting the back surface of the second solar cell, the second surface being disposed opposite the first surface; at least a portion of each of the first and second surfaces comprises a coating for connecting each of the surfaces of the at least one conductive element to a surface of the solar cell; An electrode assembly, wherein the second surface is configured to define a contact area that is substantially smaller than the contact area defined by the first surface.

2. The electrode assembly of claim 1 , wherein the second surface is substantially curved.

3. The electrode assembly of claim 2 , wherein the second surface curves outward from the conductive element.

4. The electrode assembly of claim 3 , wherein the at least one conductive element has a cross-section shaped as an elliptical segment.

5. The electrode assembly of claim 1 , wherein the second surface is substantially flat.

6. The electrode assembly of claim 1 , wherein the first surface is substantially flat.

7. The electrode assembly of claim 6 , wherein the first surface is substantially parallel to the second surface.

8. 10. The electrode assembly of claim 1, wherein the at least one conductive element comprises a third surface disposed between the first surface and the second surface, the third surface configured to space the first surface from the second surface.

9. The electrode assembly of claim 8 , wherein the third surface is substantially flat.

10. The electrode assembly of claim 8 , wherein the third surface is substantially curved.

11. The electrode assembly of claim 10 , wherein the third surface curves outward from the conductive element.

12. The electrode assembly of claim 1 , wherein the coating is configured to substantially cover the first surface and the second surface.

13. The electrode assembly of claim 12 , wherein the coating is configured to substantially cover each of the surfaces of the conductive elements.

14. 2. The electrode assembly of claim 1, wherein at least a portion of the conductive elements are disposed in or on an insulating, optically transparent film, and at least a portion of at least one of the first surface and the second surface of the at least one conductive element is exposed from the film to form ohmic contact with the front and back surfaces of the first and second solar cells, respectively.

15. 15. A solar cell assembly comprising: a first solar cell, a second solar cell, and the electrode assembly according to any one of claims 1 to 14, wherein the plurality of conductive elements are configured to electrically connect a front surface of the first solar cell to a back surface of the second solar cell.

16. 16. A method for manufacturing the solar cell assembly of claim 15, comprising: positioning the second solar cell so that its back surface faces substantially upward; overlaying a first section of the electrode assembly onto a back surface of the second solar cell such that the second surface of the at least one conductive element is positioned in contact with the back surface; connecting the second surface of the at least one conductive element onto the back surface of the second solar cell; overlaying the front surface of the first solar cell onto a second section of the electrode assembly such that the first surface of the at least one conductive element is disposed in contact with the front surface; and connecting the first surface of the at least one conductive element onto the front surface of the first solar cell.

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