Assembly for photovoltaic module, photovoltaic module and manufacturing process of the assembly and the module

Abstract

Photovoltaic module assembly, photovoltaic module and method for manufacturing the assembly and the module. Photovoltaic module assembly, comprising at least two photovoltaic cells (C1, C2), each photovoltaic cell (C1, C2) comprising a substrate (2) configured for photogenerating charge carriers, and at least one transparent conductive oxide layer (3, 4) having at least one first zone (5) having a first electrical conductivity, and second zones (10 to 17) having a second electrical conductivity strictly greater than the first electrical conductivity, the assembly comprising at least one interconnecting element (20, 21) electrically coupled to the second zones (10 to 17) to electrically connect the two cells (C1, C2) to each other, said at least one interconnecting element (20, 21) extending in a direction perpendicular to the principal direction (X). Figure for the abstract: Fig. 1

Description

Title of the invention: Assembly for a photovoltaic module, photovoltaic module and method for manufacturing the assembly and the module. Technical field

[0001] The present invention relates to a photovoltaic module assembly forming a string of photovoltaic cells. It also relates to a photovoltaic module and the manufacture of photovoltaic assemblies. STATE OF THE ART

[0002] Photovoltaic modules comprise several interconnected photovoltaic cells forming an assembly also called a "photovoltaic string". The interconnection of the cells is a major issue because it defines the electrical energy production characteristics of the modules, particularly in terms of electrical power.

[0003] There are various methods for interconnecting photovoltaic cells. A photovoltaic module can be manufactured by encapsulating the photovoltaic assemblies in a stack of polymer and / or glass-type materials. This stack protects the photovoltaic cells from the external environment while maintaining the photoelectric conversion function. Interconnection technologies are varied and generally adapted to the photovoltaic cell technologies used to create the modules. Furthermore, the way in which the photovoltaic cells are connected to each other makes it possible to improve the module's performance independently of the individual performance of the photovoltaic cells, and also to reduce electrical power losses.

[0004] Generally, the interconnection of photovoltaic cells requires the use of a large quantity of silver to make the metallic contacts on the front and back faces of the cells, which are used for the evacuation and collection of the electrical current generated by the cells. Thus, the photovoltaic industry currently consumes more than 10% of the silver produced worldwide for an annual production of 100 GW. Furthermore, for a production exceeding 3 TW, it is estimated that consumption will reach more than 50% of the silver produced worldwide if the silver consumption is 5 mg / W. Currently, a HET type photovoltaic cell, i.e. heterojunction, consumes between 25 and 40 milligrams of silver per Watt, and projections indicate that the 3 TW production will be reached in 2035. It will therefore be necessary in the future to drastically reduce silver consumption by a factor of 8 to 10, with a target of about 2 mg / W in 2035.In a photovoltaic cell, the metallic parts composed of 80% silver are thin lines. These components, with a cross-section of 540 pm², are called "fingers." These fingers collect the charge produced by the cell substrate. Within a photovoltaic module, this charge is then extracted through the elements that connect the cells, also called interconnectors, wires, or ribbons. These interconnectors are typically made of metallic wires or ribbons, whose role is to ensure electrical continuity between two cells while minimizing ohmic losses. These elements must also limit the shading they create when they cover part of the surface of a cell face that receives sunlight. These ribbons or wires are generally made of copper coated with a tin-based metal alloy, such as SnAg, SnPb, SnAgCu, SnAgBi, etc.

[0005] Currently, the most widespread interconnection method uses brazing of sheathed (or tinned) copper wires onto buses, also called busbars, located on the surface of the photovoltaic cells. Generally, the buses are created beforehand during a metallization step, usually by screen printing. The cells are connected to each other, in series or in parallel, using tinned copper strips or wires which are brazed, using a filler material from the metallic alloy coating, onto the buses present on one side of each cell. For a long time, three-bus technology was predominant on the market, but the growing interest in four- or six-bus architectures allows this interconnection method to evolve to nine buses, or even more, which are now called Multi-Busbars (MBB), i.e., assemblies with several buses.For example, Multi-Busbar technology, in addition to providing power to the modules, allows for better resistance of the modules to accelerated aging tests, a reduction in the amount of silver used in the module and therefore a reduction in production cost.

[0006] The copper wire connectors can be interconnected to the cell fingers using buses by soldering. For example, the wire connectors (circular copper wires), serving as both buses and ribbons, can be soldered directly onto the cell surface. Furthermore, pre-screen-printed silver paste solder pads can be used to solder the wire interconnectors to the busbars that interconnect the cell fingers. For example, an alloy used for soldering is lead-tin-silver based. For example, soldering can be performed using infrared beams with wire interconnectors having a diameter of 300 µm. However, this infrared soldering is carried out at a temperature close to 200 °C and can locally damage the cell.

[0007] Another method consists of connecting two neighboring cells without a bus by means of wires copper using a polymer foil. This process is usually referred to by the trademark SmartWire Connection Technology™ (SWCT). In this process, copper wires are embedded in a polymer foil or matrix and coated with a low-temperature solder alloy, primarily bismuth-based, with a melting point below 138°C. The use of a low-temperature solder alloy reduces stress at the contact points between the copper wire and the cartridge fingers. Furthermore, the polymer matrix is ​​a two-layer heat-sealable layer: a first layer with adhesive properties on the bottom and a second layer providing mechanical support on the top. The copper wire remains in contact with the cartridge metallization, and the film comprising the polymer matrix and the copper wires is positioned on the cartridge.The cell fingers can be reduced in width, from 35 to 40 µm, resulting in lower silver consumption compared to bus technologies. The copper wires have a diameter of approximately 200 or 250 µm, and with narrower fingers, there is less shading on the cells. However, this method also requires a significant amount of silver to connect the fingers to the copper wires.

[0008] For example, one can cite US patent application US20140182675 and international application WO 2014 / 150235, which disclose a photovoltaic cell comprising metallization fingers located on the front face of the cell. US patent application US 20120015147 discloses a photovoltaic cell comprising a substrate, a first layer on the substrate comprising metal oxide nanoparticles, and a second layer covering the first layer, the second layer comprising dopant elements, such as aluminum, gallium, indium, or boron.

[0009] We can also cite Korean patent application KR20130085188, which discloses a photovoltaic cell comprising a substrate layer for photogenerating charge carriers, and a transparent conductive oxide layer, also called a TCO (transparent conductive oxide) layer, or commonly a TCO layer, disposed on one face of the substrate. The transparent conductive oxide layer has a pattern with ribs forming grooves within which is disposed a layer of aluminum-doped zinc oxide in electrical contact with metallization fingers formed on the front face of the cell.

[0010] International application WO 2014 / 128032 discloses a photovoltaic cell comprising metallization fingers and a transparent conductive oxide layer comprising highly conductive lines aligned under and along the metallization fingers.

[0011] But these cells do not allow for a significant reduction in silver consumption used to interconnect two photovoltaic cells.

[0012] Other techniques exist for directly connecting copper wires in the TCO layer of a cell at the heterojunction, but a loss of electrical power is observed compared to the same copper wires connected to the cell fingers. Furthermore, the removal of the fingers leads to a sharp increase in series resistance, which consequently results in a significant decrease in module power. This sharp increase in series resistance stems from an increase in the lateral resistance of the free carriers in the TCO layer. Indeed, in a cell at the heterojunction, the free carriers must travel laterally through the TCO layer before reaching the cell fingers.

[0013] An object of the present invention is therefore to provide a solution for interconnecting photovoltaic cells while limiting the drawbacks mentioned above. In particular, there is a need to provide a reliable method for interconnecting photovoltaic cells, while reducing manufacturing costs, and especially reducing the expenditure of money.

[0014] The other objects, features and advantages of the present invention will become apparent from an examination of the following description and accompanying drawings. It is understood that other advantages may be incorporated. SUMMARY

[0015] To achieve this objective, a photovoltaic module assembly is proposed, comprising at least two photovoltaic cells.

[0016] Each photovoltaic cell comprises: - a substrate configured to photogenerate charge carriers, and - at least one transparent conductive oxide layer comprising at a first zone exhibiting a first electrical conductivity, and second zones exhibiting a second electrical conductivity strictly greater than the first electrical conductivity, the second zones extending longitudinally along lines parallel to a main direction.

[0017] The assembly includes at least one electrically coupled interconnection element with the second zones of each of said at least two photovoltaic cells to electrically connect them together.

[0018] Said at least one interconnecting element extends in a direction perpendicular to the main direction.

[0019] Each photovoltaic cell is devoid of an additional metallization line electrically connecting said at least one interconnecting element with said at least one transparent conductive oxide layer.

[0020] Thus, a set of interconnected photovoltaic cells is provided. and devoid of additional silver plating. Such an assembly uses a minimal amount of conductive material.

[0021] According to another aspect, a photovoltaic module is proposed, comprising at least one assembly as defined above.

[0022] According to another aspect, a method for manufacturing an assembly for a photovoltaic module as defined above is proposed, comprising: - a supply of at least two photovoltaic cells; each photovoltaic cell comprising: • a substrate configured to photogenerate charge carriers, and • at least one transparent conductive oxide layer comprising at less a first zone exhibiting a first electrical conductivity, and - a formation of second zones exhibiting a second electrical conductivity strictly greater than the first electrical conductivity, the second zones extending longitudinally along lines parallel to a principal direction.

[0023] The method includes depositing at least one electrically coupled interconnecting element with the second zones of each of said at least two photovoltaic cells to electrically connect them together. BRIEF DESCRIPTION OF THE FIGURES

[0024] The aims, objects, features and advantages of the invention will become clearer from the detailed description of an embodiment thereof, which is illustrated by the following accompanying drawings in which:

[0025] [Fig.1] Fig.1 schematically represents a perspective view of an embodiment of an assembly for a photovoltaic module;

[0026] [Fig.2] Fig.2 schematically represents a perspective view of another method of constructing an assembly for a photovoltaic module;

[0027] [Fig.3]

[0028] [Fig.4]

[0029] [Fig. 5] Figures 3 to 5 schematically represent cross-sectional views of other methods of implementing an assembly for a photovoltaic module;

[0030] [Fig.6]

[0031] [Fig. 7] Figures 6 and 7 schematically represent implementation steps of a manufacturing process for an assembly for a photovoltaic module.

[0032] The drawings are given by way of example and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate understanding of the invention and are not necessarily to scale with the applications practices. DETAILED DESCRIPTION

[0033] Before beginning a detailed review of embodiments and implementations of the invention, optional features which may possibly be used in association or alternatively are stated below.

[0034] According to one example, at least one photovoltaic cell is of the heterojunction type in which the substrate comprises crystalline silicon and hydrogenated amorphous silicon.

[0035] According to one example, at least one photovoltaic cell comprises first and second layers of transparent conductive oxide arranged respectively in contact with first and second faces of the substrate, the second face of the substrate being located on a side opposite to that of the first face.

[0036] According to one example, for at least one photovoltaic cell, the second zones are separated by a distance greater than or equal to a width of at least one second zone, the width being measured along a direction perpendicular to the main direction.

[0037] According to one example, for at least one photovoltaic cell, said at least a first zone has a face, called internal, in contact with at least one face of the substrate, and a face, called external, opposite to the internal face, having several pairs of ribs, each pair of ribs delimiting between them a groove in which a second zone is disposed.

[0038] According to one example, for at least one photovoltaic cell, the second zones are arranged in contact with at least one face of the substrate, and said at least one photovoltaic cell comprises several first zones arranged in contact with said at least one face of the substrate.

[0039] According to one example, for at least one photovoltaic cell, said at least one first zone has a face, called internal, in contact with at least one face of the substrate, and a face, called external, opposite to the internal face, in contact with the second zones.

[0040] According to another example, for at least one photovoltaic cell, the second zones extend longitudinally along continuous lines respectively.

[0041] According to another example, for at least one photovoltaic cell, the second zones extend longitudinally along discontinuous lines respectively.

[0042] According to one example, said at least one interconnecting element is in direct mechanical contact with the second zones of at least one photovoltaic cell.

[0043] According to one example, the assembly includes a dielectric layer partially covering the first zone.

[0044] According to one example, for at least one photovoltaic cell, the assembly comprises metallized pads, each metallized pad being arranged in mechanical contact with a second zone of said at least one photovoltaic cell and said at least one interconnecting element.

[0045] According to one example, at least one photovoltaic cell is of the simple junction type comprising a single layer of transparent conductive oxide.

[0046] According to one example, at least one photovoltaic cell is of the double junction type comprising two layers of transparent conductive oxide.

[0047] In the present invention, types of doping will be indicated. Doping is understood to mean the addition of a minimal amount of impurities to a layer comprising a single crystal or a polycrystal, to transform it into an electrically conductive layer comprising free charge carriers. These dopings are non-limiting examples.

[0048] Figures 1 to 5 show a photovoltaic module assembly 1. Assembly 1 comprises at least two photovoltaic cells Cl, C2. A photovoltaic module comprises an assembly of photovoltaic cells 2, 20 interconnected to produce a current, and assembly 1 is also called a "photovoltaic string". Each photovoltaic cell Cl, C2 comprises a substrate 2 and at least one transparent conductive oxide layer 3, 4. The substrate 2 is configured to photogenerate charge carriers. For example, a Cl, C2 cell may be of the HET type, i.e., of the heterojunction type. A heterojunction-type cell is a Cl, C2 cell comprising a crystalline silicon substrate and at least one layer of hydrogenated amorphous silicon.

[0049] Generally, a photovoltaic cell Cl, C2 converts part of the light radiation into electrical energy. For this purpose, substrate 2 is configured to generate, upon receiving light radiation, free charges to move and intended to be collected to produce an electric current.

[0050] The conductive oxide layer 3, 4 is also called the TCO layer. The Cl, C2 cell may comprise a single TCO layer disposed in contact with a first face 30 of the substrate 2. Advantageously, a Cl, C2 cell may comprise a first TCO layer disposed in contact with the first face 30 of the substrate 2 and a second TCO layer disposed in contact with a second face 31 of the substrate 2, the second face 31 being located on the opposite side from the first face 30. A TCO layer 3, 4 allows the collection of charges produced by the substrate 2 and facilitates the movement of these generated charges. A Cl, C2 photovoltaic cell may be a single-junction cell based on crystalline silicon of the heterojunction type or a so-called tandem cell, i.e., a double-junction cell comprising at least one sub-cell based on crystalline silicon of the heterojunction type, and in particular a cell tandem cell comprising a perovskite-based subcell and a heterojunction subcell. In the case of a tandem cell, there are also two TCO3,4 layers on both sides of the cell.

[0051] In particular, a TCO 3,4 layer comprises at least one first zone 5 exhibiting a first electrical conductivity. Furthermore, a TCO 3,4 layer comprises several second zones 10 to 17 exhibiting a second electrical conductivity strictly greater than the first electrical conductivity. The second zones 10 to 17 are also called highly conductive zones, and the first zone(s) 5 are called weakly conductive zones. For example, the first electrical conductivity of a first zone 5 can be obtained by first doping the TCO 3,4 layer at the location of the first zone 5. Moreover, the second electrical conductivity of a second zone 10 to 17 can be obtained by second doping the TCO 3,4 layer at the location of the second zone 10 to 17. According to one example, the first doping is different from the second doping so as to obtain distinct electrical conductivities.Alternatively, the first and second dopings could be identical, with the first and second zones 5 and 10 to 17 having distinct thicknesses to obtain distinct electrical conductivities, the thicknesses being measured along a direction perpendicular to the first face 30 of the substrate 2. Thus, for the same doping, increasing the thickness of a zone of the TCO layer 3, 4 decreases the electrical resistance of the zone. For example, for the same doping, the TCO layer 3, 4, at the location of the second zones 10 to 17 has a thickness strictly greater than that of the TCO layer 3, 4 at the location of the first zones 5.

[0052] More particularly, the second zones 10 to 17 extend longitudinally along lines parallel to a main direction X.

[0053] Furthermore, assembly 1 includes at least one interconnection element 20, 21 electrically coupled with the second zones 10 to 17 of each of the photovoltaic cells Cl, C2 of assembly 1 to electrically connect them together.

[0054] More specifically, at least one interconnection element 20, 21, and preferably each interconnection element 20, 21, extends in a direction inclined to the principal direction X at an angle between 85° and 105°, preferably 90°. Advantageously, the interconnection elements 20, 21 extend in a direction perpendicular to the principal direction X. Thus, it is not necessary to align the interconnection elements 20, 21 with the second zones 10 to 17.

[0055] In particular, each photovoltaic cell Cl, C2 is devoid of an additional metallization line electrically connecting at least one interconnecting element, and preferably each interconnecting element 20, 21, with the transparent conductive oxide layer 3, 4 comprising the second zones 10 to 17. In other words, a cell Cl, C2 does not include a metallization line connecting the interconnecting element(s) 20, 21 with a second zone 10 to 17, nor one or more metallization lines connecting the interconnecting element(s) 20, 21 with a first zone 5. These metallization lines are often referred to as "fingers." The electrical coupling between the interconnecting elements and the second zones 10 to 17 is achieved, for example, directly, i.e., without the intermediary of metallization fingers.

[0056] The interconnecting elements 20, 21 may, for example, comprise tinned copper wires or ribbons, i.e., copper wires or ribbons onto which a layer of tin-based metal alloy, for example SnAg, SnPb, SnBiPb, SnAgCu, SnAgBi, etc., has been deposited to protect them from oxidation. The interconnecting elements 20, 21 may be bonded or soldered to the TCO layer 3, 4. Alternatively, the interconnecting elements 20, 21 are placed directly onto the TCO layer 3, 4, in mechanical contact with the second zones 10 to 17, and the electrical connection between the interconnecting elements 20, 21 and the second zones 10 to 17 may be made subsequently during a lamination step.Lamination is understood to mean a step comprising the supply of heat to the photovoltaic cells Cl, C2 so as to perform a brazing of at least one interconnection element 20, 21 with the second zones 10 to 17 of each photovoltaic cell Cl, C2 so as to mechanically and electrically couple the interconnection elements 20, 21 with the second zones 10 to 17. .

[0057] Thus, by adding second zones 10 to 17 with a higher electrical conductivity than the first zone(s) 5, zones 10 to 17 with a lower electrical resistance than the first zone(s) 5 are created. The second zones 10 to 17 facilitate the movement of charges produced by the substrate 2, and in particular lateral movement along a secondary direction Y perpendicular to the main direction X. In other words, the second zones 10 to 17 prevent a significant increase in the series resistance in the module due to the increased lateral transport distance within the TCO layer 3, 4. Furthermore, the collection of charge carriers by the interconnecting elements 20, 21 is improved because the interconnecting elements 20, 21 extend at an angle between 85° and 105°, preferably 90°, with the second zones 10 at 17.Advantageously, the collection of load carriers is further improved when the interconnection elements 20,21 extend perpendicularly to the second zones 10 to 17.

[0058] Furthermore, the interconnecting elements 20, 21 are separated by a first distance 38, the first distance 38 being measured along the principal direction X. By way of example, the first distance 38 can be between 2 and 16 millimeters, from Preferably between 2 and 8 mm. For example, for at least one photovoltaic cell Cl, C2, the second zones 10 to 17 are separated by a second distance 40 greater than or equal to a width 39 of at least one second zone 10 to 17, the width being measured along a direction perpendicular to the principal X direction. For example, the second distance 40 can be between 0.1 and 2 mm, preferably between 0.5 and 1 mm. Advantageously, the first distance 38 is strictly greater than the second distance 40. Thus, the distance traveled by the free charge carriers in the TCO layer 3, 4 to reach the second zones 10 to 17 is much less than the distance to be traveled to reach the interconnecting elements 20, 21 via the first zone 5.

[0059] Generally, doping the second zones 10 to 17 consists of adding impurities locally to the second zones 10 to 17 in order to increase the electrical conductivity of the second zones 10 to 17. It is noted that the more the doping of the second zones 10 to 17 increases, the more the electrical conductivity of the second zones 10 to 17 increases, which decreases the electrical resistance, known as the series resistance, of the second zones 10 to 17. Furthermore, an increase in the doping of the second zones 10 to 17 also leads to an increase in the absorption of light by the second zones 10 to 17, due in particular to the increase in the density of charge carriers, which reduces the current generated by the photovoltaic module. In other words, set 1 associates one or more regions of a TCO layer 3, 4 which are not very conductive 5 and therefore not very absorbent of light with highly conductive regions 10 to 17.Advantageously, for a front face surface area Sfa 100 of a Cl, C2 cell, we create second zones 10 to 17 whose total surface area present at the front face 100 of the Cl, C2 cell is much smaller than the front face surface area Sfa 100 of the Cl, C2 cell. Thus, we promote the collection of charge carriers, to increase the current produced, while decreasing the effect of light absorption by the second zones 10 to 17.

[0060] The second highly conductive zones 10 to 17 reduce the lateral resistance in the TCO layer 3, 4, allowing current to flow more easily in the TCO layer 3, 4. In addition, doping the second zones 10 to 17 with conductive elements also results in a lower electrical resistance between the second zones 10 to 17 and the interconnecting elements 20, 21.

[0061] For example, the second zones 10 to 17 can be created by modifying the first zone 5, by introducing hydrogen, or by introducing conductive elements locally into the first zone 5. Alternatively, the second zones 10 to 17 can be deposited by sputtering using a mask or created by localized laser doping or by localized hydrogen implantation followed by annealing, i.e., heating the Cl,C2 cell to a temperature between between 100 and 800 °C, preferably between 200°C and 300°C.

[0062] For example, hydrogen can be implanted to introduce impurities into the first zone 5, in order to modify its electrical properties. These modifications are generated by the intrinsic properties of the introduced element, in particular by the interactions, i.e., the defects, that it generates in the first zone 5. This step is particularly well suited to the surface treatment of the TCO layer 3, 4. Implantation by plasma immersion can also be used, for example, ion implantation by plasma immersion (denoted PIII), ion implantation by plasma source (denoted PSII), or even plasma-based ion implantation (denoted PBII).

[0063] In [Fig. 6], an example is shown in which the TCO 3, 4 layer is immersed in a plasma 301 containing ions 300 to be implanted. To create the second zones 10 to 17, a negative voltage (between -20V and -100kV), generally pulsed, is applied to the TCO layer 3, 4 so that a sheath 302 forms around it. The ions 300 located in this sheath 302 are accelerated by an electric field inside the sheath 302 and are then implanted into the TCO layer 3, 4.

[0064] In [Fig.7], another embodiment for carrying out the Second zones 10 to 17 in the TCO 3, 4 layer. In this alternative implementation, hydrogen implantation can be performed. This hydrogen implantation can be done selectively by implantation through a mask. To perform the hydrogen implantation, an accelerating voltage between 0.5 and 6 kV (preferably between 1 and 4 kV) is used, and the dose is between 11014 and 11016 cm² (preferably between 51014 and 51015 cm²). To improve hydrogen diffusion in the TCO 3, 4 layer, the TCO 3, 4 layer can then be annealed at different temperatures, for example, between 100 and 450 °C. For example, when using an Indium Tin Oxide (ITO) layer, hydrogen implantation leads to a decrease in the electrical resistivity of the second zones 10 to 17, regardless of the subsequent annealing temperature.In particular, for an annealing temperature of 300 °C or lower, the electrical resistivity of the TCO layer can be halved. In other words, second zones 10 to 17 can be obtained with an electrical conductivity approximately twice that of the first zone 5. Furthermore, by using higher annealing temperatures, i.e., above 300 °C, the difference in electrical conductivity between the second zones 10 to 17 and the first zone 5 is less significant. Moreover, above an annealing temperature of 350 °C, the difference in electrical conductivity is negligible. Thus, an annealing temperature of 350 °C or lower, and preferably one strictly below 300 °C, should be used. In general, for all annealing temperatures, we obtain second zones 10 to 17 having a resistivity less than or equal to 40 Ohms / square, that is to say a resistivity less than or equal to 1.5 x 1040hm*cm, with a thickness of the second zones of 38 nm, the thickness being measured along a direction perpendicular to the first face 30 of the substrate 2.

[0065] Advantageously, doping the first and second zones 5, 10 to 17, makes it possible to obtain second zones 10 to 17 having an electrical conductivity with a factor of between 15 and 40 times, preferably 30 times, the electrical conductivity of the first zone 5. For example, for highly conductive zones, to obtain 5 Ohms / square, a TCO layer thickness of 300 nm with a resistivity of 1.5 x 10⁴ Ohm*cm is required. For weakly conductive zones, 400 Ohms / square can be obtained by adding oxygen during deposition; for a thickness of 30 nm, a resistivity of 12 x 10⁴ Ohm*cm is thus obtained; for 100 nm, 40 x 10⁴ Ohm*cm is obtained, which gives a ratio of approximately 27.

[0066] In order to limit the absorption of light by the second zones 10 to 17 of the face 100, 101 of the cell Cl, C2 intended to receive light, doping will be used to obtain, for a thickness H1 of the second zones 10 to 17 equal to 70 nm, an electrical resistivity between 300 and 400 Ohms / square. That is to say, between 21 x 10⁴ Ohm*cm for 70 nm and 28 x 10⁴ Ohm*cm for 70 nm. The thickness Hl, or height, of the second zones 10 to 17 is measured along a direction Z perpendicular to the main direction X and the secondary direction Y. For example, for a thickness Hl between 15 and 30 nanometers, doping will be used to obtain an electrical resistivity equal to 200 Ohms / square, that is to say an electrical resistivity equal to 3x10 4 Ohm*cm for 15 nm or equal to 6x10 4 Ohm*cm for 30 nm.

[0067] Furthermore, in order to create the first weakly conductive zone 5, the charge carrier density is limited by reducing the doping used to generate these carriers. Thus, the first weakly conductive zone 5 will be more transparent to light radiation, i.e., less absorbent.

[0068] Generally speaking, it should also be noted that the electrical conductivity θ (with units of S / m, or Siemens per meter, or (Ohms*meter)) is the inverse of the electrical resistivity θ (with units of Ohms*meter), in other words: θ = 1 / θ (equation 1). In the remainder of the description, and for the sake of simplification, values ​​of electrical resistivity θ will be given as examples for the first and second zones 5, 10 to 17.

[0069] For example, the first zone 5 can be made to have an electrical resistivity between 40 and 400 Ohms / square, preferably between 150 and 250 Ohms / square (with 150 Ohms / square corresponding to 10 x 10⁴ Ohm*cm for 70 nm, and 250 Ohms / square corresponding to responding to 17x10 4 for 70 nm).

[0070] Advantageously, the first zone 5 has an absorption of light, in particular light with a wavelength between 300 and 1200 nanometers, of less than 2%, and preferably less than 1%. For example, the first zone 5 may have a refractive index between 1.8 and 2.1, preferably between 1.9 and 2. Furthermore, the thickness H2 of the first zone 5 is between 5 and 70 nanometers (when the Cl,C2 cell comprises a single TCO3 layer), preferably between 15 and 30 nanometers (when the Cl,C2 cell comprises two TCO3,4 layers). The thickness H2 is measured along the Z direction, perpendicular to the principal X and secondary Y directions.Various materials can be used to create the first zone 5, for example using a layer of polycrystalline ITO, or a layer of hydrogen-doped indium, or a layer of tungsten-doped indium, or a layer of zinc-doped indium, a layer of aluminum-doped zinc oxide (ZnO), or a layer of gallium-doped zinc oxide (ZnO), or even a layer of arsenic-doped tin oxide (SnO2).

[0071] For example, second zones 10 to 17 can be made highly conductive with a minimum achievable electrical resistivity of approximately 1.5 x 10⁴ Ohm*cm. In other words, the electrical conductivity of the second zones 10 to 17 is strictly greater than the conductivity of the first zone 5.

[0072] Various materials can be used to create the second zones 10 to 17. For example, a layer of polycrystalline ITO with a resistivity of 1.5 x 10⁴ Ohm*cm can be used. A layer of aluminum-doped zinc oxide (AZO) with a resistivity of 2.2 x 10⁴ Ohm*cm can be used. A layer of aluminum-doped zinc oxide (ZnO) with a resistivity of 1.4 x 10⁴ Ohm*cm can be used. A layer of galium-doped zinc oxide (ZnO) with a resistivity of 1.2 x 10⁴ Ohm*cm can be used. A layer of arsenic-doped tin oxide (SnO₂) with a resistivity of 1.5 x 10⁴ Ohm*cm can be used. Preferably, we choose to create second zones 10 to 17 with a resistivity less than or equal to 1.5 x 0.4 Ohm*cm.

[0073] For example, the second zones 10 to 17 can have a width 39 of between 5 and 30 pm. Furthermore, the second zones 10 to 17 can be separated by a distance 40 of between 0.1 and 1 mm. In addition, a height H1 of the second zones 10 to 17 can be between 70 and 300 nanometers. In the example illustrated in [Fig. 1], the second zones 10 to 17 are not in contact with the first face 30 of the substrate 2. That is to say, the height H2 of the first zone 5 is strictly greater than the height H1 of the second zones 10 to 17.

[0074] The interconnecting elements 20, 21 can be brought into contact with the second zones 10 to 17 located on the front faces 100 of the cells for parallel mounting photovoltaic cells Cl, C2. When it is desired to mount the photovoltaic cells in series, the interconnection elements 20, 21 are located on the front face 100 of a first cell Cl, and on the rear face 101 of a second photovoltaic cell C2.

[0075] Advantageously, the interconnecting elements 20, 21 are in direct mechanical contact with the second zones 10 to 17 of at least one photovoltaic cell Cl, C2. The interconnecting elements 20, 21 may be copper wires, preferably tin-plated, i.e., comprising an outer coating of tin, for example, tin-based, bismuth-silver (SnBiAg), or tin-based, copper-silver (SnAgCu), or tin-based, bismuth-lead (SnBiPb), or tin-based, and lead (SnPb). The cross-sectional diameter of the copper wires 20, 21 may be between 150 and 250 micrometers. Advantageously, the interconnecting elements 20, 21 are spaced at a distance 38 of between 2 and 8 mm.

[0076] Alternatively, as illustrated in [Fig. 5], for at least one photovoltaic cell Cl, C2, the assembly 1 comprises metallized pads 60, each metallized pad 60 being arranged in mechanical contact with a second zone 10 to 17 of the photovoltaic cell Cl, C2 and with at least one interconnection element 20, 21. More particularly, a metallized pad 60 does not correspond to a line of metallization, in particular because a maximum width or length of a metallized pad 60 is strictly less than a distance separating two interconnection elements 20, 21. Thus, a metallized pad 61 is not configured to electrically connect, by itself, two distinct interconnection elements 20, 21. The metal studs 60 can be made from a conductive glue to improve the contact between the interconnecting elements 20, 21 and the second zones 10 to 17.The conductive adhesive can be deposited in a continuous line under the interconnecting elements 20, 21 or on the second zones 10 to 17 in a localized manner at the intersection between the interconnecting elements 20, 21 and the second zones 10 to 17.

[0077] Figures 1 and 2 show an embodiment of an assembly 1 of two photovoltaic cells Cl, C2. For each cell Cl, C2, the first zone 5 of at least one TCO layer 3, 4 has a face 41, called the inner face, in contact with at least one face 30, 31 of the substrate 2, and a face 42, called the outer face, opposite the inner face 41. Generally, the inner faces 41 of the TCO layers 3, 4 are in contact with the substrate 2. In other words, the outer faces 42 of the TCO layers 3, 4 are at a distance from the substrate 2. Furthermore, the outer face 42 of a TCO layer 3, 4 has several pairs of ribs 43, 44, each pair of ribs 43, 44 delimiting between them a groove 45 in which a second zone 10 is located. 17. For example, for at least one photovoltaic cell Cl, C2, the second zones 10 to 14 extend longitudinally along lines respectively continuous. For example, the continuous lines are parallel to the main direction X. Alternatively, the second zones 15 to 17 extend longitudinally along dashed lines. For example, the dashed lines are parallel to the main direction X.

[0078] Figure 3 shows another embodiment of a photovoltaic cell Cl, C2 of an assembly 1, in which the second zones 10 to 17 of at least one TCO layer 3, 4 are arranged in contact with at least one face 30, 31 of the substrate 2. Furthermore, the photovoltaic cell Cl, C2 comprises several first zones 5 arranged in contact with the face 30, 31 of the substrate 2. In this embodiment, second zones 10 to 17 can be made having a height H1 greater than or equal to a height H2 of the first zone 5. Preferably, the height H1 is strictly greater than the height H2 of the first zone 5.

[0079] Figures 4 and 5 show another embodiment of a photovoltaic cell Cl, C2, in which the first zone 5 of at least one TCO layer 3, 4 is advantageously in the form of a continuous layer, having an inner face 41 in contact with at least one face 30, 31 of the substrate 2, and an outer face 42 opposite the inner face 41, in contact with the second zones 10 to 17. In other words, the second zones 10 to 17 are deposited / formed on the surface of the first zone 5 and more particularly on the outer face 42 of the first zone 5. They are then not directly in contact with the inner face 41 of the substrate 2. In this other embodiment, the first zone 5 can be partially covered with a dielectric layer 61, preferably transparent. In other words, the dielectric layer 61 comprises several parts arranged between two neighboring second zones 10 to 14.The transparent dielectric layer 61 limits light reflection by the TCO layer 3, 4, particularly by the first zone 5. Indeed, when the first zone 5 has a small thickness H2, i.e., a thickness less than or equal to 30 nm, light reflection by the first zone 5 increases. The transparent dielectric layer 61 has a thickness H3 between 30 and 100 nanometers. Thus, the transparent dielectric layer 61 comprises several parts respectively located between two second zones 10 to 17. For example, the transparent dielectric layer 61 can comprise silicon nitride (SiN), silicon dioxide (SiO), or silicon oxynitride (SiOxNy), alone or in combination. Advantageously, the transparent dielectric layer 61 has an optical index close to that of the TCO layer 3, 4, for example an optical index between 1.8 and 2.1, preferably between 1.9 and 2.

[0080] It can be noted that the assembly 1 just described makes it possible to avoid having to make silver fingers on a face 100, 101 of a photovoltaic cell Cl, C2 electrically connected to interconnecting elements 20, 21. In other In terms, we provide an assembly 1 devoid of additional metallization lines electrically connecting interconnection elements 20, 21 with a TCO layer.

[0081] An example of a manufacturing process for assembly 1 as defined above will now be described. The process comprises the following main steps: - supplying at least two photovoltaic cells Cl, C2; each photovoltaic cell Cl, C2 comprising a substrate 2 configured for photogenerating charge carriers, and at least one transparent conductive oxide layer 3, 4 having at least a first zone 5 having a doping configured such that said at least a first zone 5 has a first electrical conductivity; and - a formation of second zones 10 to 17 exhibiting a doping configured such that the second zones 10 to 17 have a second electrical conductivity strictly greater than the first electrical conductivity, the second zones 10 to 17 extending longitudinally along lines parallel to a principal direction X.

[0082] The method further comprises depositing at least one interconnecting element 20, 21 electrically coupled to the second zones 10 to 17 of each photovoltaic cell Cl, C2 to electrically connect them together. In particular, at least one interconnecting element is deposited extending in a direction inclined with respect to the principal direction X at an angle between 85° and 105°, preferably at 90°.

[0083] For example, the interconnecting elements 20, 21 can be deposited on the cell Cl, C2 using a polymer sheet according to the SmartWire Connection Technology™ (SWCT) technique.

[0084] The assembly for a photovoltaic module and the method for manufacturing such an assembly Together, these components significantly reduce silver consumption per cell. Furthermore, they eliminate the need for silver plating on each individual cell. This elimination also allows for increased cell power by reducing shading caused by silver plating, such as from fingers, on the light-receiving side of the photovoltaic cell.

Claims

Demands

1. A photovoltaic module assembly comprising at least two photovoltaic cells (Cl, C2), characterized in that each photovoltaic cell (Cl, C2) comprises: • a substrate (2) configured for photogenerating charge carriers, and • at least one transparent conductive oxide layer (3, 4) having at least one first zone (5) having a first electrical conductivity, and second zones (10 to 17) having a second electrical conductivity strictly greater than the first electrical conductivity, the second zones (10 to 17) extending longitudinally along lines parallel to a principal direction (X), the assembly comprising at least one interconnecting element (20, 21) electrically coupled to the second zones (10 to 17) of each of said at least two photovoltaic cells (Cl, C2) for electrically connecting them together, said at least one interconnecting element (20,21) extending in a direction perpendicular to the main direction (X), each photovoltaic cell (Cl, C2) being devoid of an additional metallization line electrically connecting said at least one interconnecting element (20, 21) with said at least one transparent conductive oxide layer (3, 4).

2. Assembly according to claim 1, wherein at least one photovoltaic cell (Cl, C2) comprises first and second layers of transparent conductive oxide (3, 4) arranged respectively in contact with first and second faces (30, 31) of the substrate (2), the second face (31) of the substrate (2) being located on a side opposite to that of the first face (30).

3. Assembly according to any one of claims 1 to 2, wherein, for at least one photovoltaic cell (Cl, C2), the second zones (10 to 17) are separated by a distance (40) greater than or equal to a width (39) of at least one second zone (10 to 17), the width (39) being measured along a direction (Y) perpendicular to the principal direction (X).

4. Assembly according to any one of claims 1 to 3, wherein at least one photovoltaic cell (Cl, C2) is of the heterojunction type in which the substrate (2) comprises crystalline silicon and hydrogenated amorphous silicon.

5. Assembly according to any one of claims 1 to 4, wherein, for at least one photovoltaic cell (Cl, C2), said at least a first zone (5) has a face (41), said internal, in contact with at least one face (30, 31) of the substrate (2), and a face (42), said external, opposite to the internal face (41), having several pairs of ribs (43, 44), each pair of ribs (43, 44) delimiting between them a groove (45) in which a second zone (10 to 17) is disposed.

6. Assembly according to any one of claims 1 to 4, wherein, for at least one photovoltaic cell (Cl, C2), the second zones (10 to 17) are arranged in contact with at least one face (30, 31) of the substrate (2), and said at least one photovoltaic cell (Cl, C2) comprises several first zones (5) arranged in contact with said at least one face (30, 31) of the substrate (2).

7. Assembly according to any one of claims 1 to 4, wherein, for at least one photovoltaic cell (Cl, C2), said at least one first zone (5) has a face (41), said internal, in contact with at least one face (30, 31) of the substrate (2), and a face (42), said external, opposite the internal face (41), in contact with the second zones (10 to 17).

8. Assembly according to any one of claims 1 to 7, wherein, for at least one photovoltaic cell (Cl, C2), the second zones (10 to 17) extend longitudinally along continuous lines respectively.

9. Assembly according to any one of claims 1 to 7, wherein, for at least one photovoltaic cell (Cl, C2), the second zones (10 to 17) extend longitudinally along respectively discontinuous lines.

10. Assembly according to any one of claims 1 to 9, wherein said at least one interconnecting element (20, 21) is in direct mechanical contact with the second zones (10 to 17) of at least one photovoltaic cell (Cl, C2).

11. Assembly according to any one of claims 1 to 10, comprising a dielectric layer (61) partially covering the first zone (5).

12. Assembly according to any one of claims 1 to 9, wherein, for at least one photovoltaic cell (Cl, C2), the assembly comprises

13.

14.

15.

16. metallized pads (60), each metallized pad (60) being arranged in mechanical contact with a second zone (10 to 17) of said at least one photovoltaic cell (Cl, C2) and said at least one interconnection element (20, 21). Assembly according to any one of claims 1 to 12, wherein at least one photovoltaic cell (Cl, C2) is of the single junction type comprising a single layer of transparent conductive oxide (3). An assembly according to any one of claims 1 to 13, wherein at least one photovoltaic cell (Cl, C2) is of the double-junction type comprising two layers of transparent conductive oxide (3, 4). A photovoltaic module, comprising at least one assembly according to any one of the preceding claims. A method for manufacturing an assembly for a photovoltaic module according to any one of claims 1 to 14, comprising: • a supply of at least two photovoltaic cells (Cl, C2); each photovoltaic cell (Cl, C2) comprising: • a substrate (2) configured to photogenerate charge carriers, and • at least one transparent conductive oxide layer (3, 4) comprising at least one first zone (5) exhibiting first electrical conductivity, and • a formation of second zones (10 to 17) exhibiting a second electrical conductivity strictly greater than the first electrical conductivity, the second zones (10 to 17) extending longitudinally along lines parallel to a principal direction (X), and • a deposit of at least one interconnecting element (20, 21) electrically coupled with the second zones (10 to 17) of each of said at least two photovoltaic cells (Cl, C2) to electrically connect them together, said at least one interconnecting element (20, 21) extending in a direction perpendicular to the main direction (X), and each photovoltaic cell (Cl, C2) being devoid of an additional metallization line electrically connecting said at least one interconnecting element (20, 21) with said at least one transparent conductive oxide layer (3, 4). 20

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