Method for bonding an interconnection element to a photovoltaic cell, and associated device

Abstract

One aspect of the invention relates to a method for bonding an interconnection element (INTR) to a photovoltaic cell comprising the steps of: - depositing an electrically conductive adhesive film (F1) on the interconnection element (INTR); and - depositing the interconnection element (INTR) on the photovoltaic cell (CELL1), the electrically conductive adhesive film (F1) being arranged in contact with the photovoltaic cell (CELL1).

Description

DESCRIPTION TITLE: METHOD FOR BONDING AN INTERCONNECTION ELEMENT TO A PHOTOVOLTAIC CELL AND ASSOCIATED DEVICE TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of the interconnection of photovoltaic cells and in particular the connection of an interconnection element to the photovoltaic cells. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] A terrestrial photovoltaic module consists of photovoltaic cells, also called "solar cells", electrically connected to each other (for example in series), also called "interconnected", and encapsulated in a stack of materials such as polymers and / or glass. This stack protects the photovoltaic cells from the external environment while maintaining their photoelectric conversion function.

[0003] Interconnection technologies are varied and generally adapted to the photovoltaic cell technologies used to create the targeted photovoltaic module. The way in which the cells are interconnected can improve the performance of the produced module, independently of the intrinsic performance of the cells, by reducing so-called "CTM" losses (cell to module). The most widespread interconnection technology currently used is the soldering of sheathed copper strips onto conductive tracks on the surface of the cells, called "busbars", these busbars being created beforehand during a cell metallization step. By "sheathed", we mean that each copper strip is coated with a fusible alloy that can melt at relatively low temperatures, for example below 250 °C.For example, it is an alloy containing tin (which is why the term "tinned ribbon" is often used). Busbars are generally made by screen printing an electrically conductive ink on the front and / or rear faces of the cells. The cells can be connected together in series, using copper ribbons that are soldered to the busbars present on the front and / or rear faces of the cells. If one of the embodiments, called "3BB" for "three busbars" has been predominant on the market, the increase in the number of busbars is of growing interest. Four, i. Six or even eight busbars are currently being considered. Adding more busbars increases the module's electrical power. Redundancy between the busbars also reduces electrical losses if one of the busbars breaks, as electrical currents are diverted to the intact busbars.

[0004] As an alternative to copper ribbons, copper wire conductors, called "wires" in English, are also used to interconnect the cells. The wires, due to their circular cross-section, offer reduced shadowing on the cells. The wires can be soldered onto the cells to act as a means of transporting electric currents and also to serve as busbars. For this, silver paste pads, intended to be soldered to the wires, are previously screen-printed on the cells. The wires are then soldered using an alloy such as SnPb or SnPbAg or a metal alloy containing Bi (which has the effect of lowering the melting point temperature of the alloy). The pads are arranged at the intersection between the collection electrodes extending over the photovoltaic cells. This method makes it possible to solder a large number of wires onto a cell, for example twelve or fifteen wires.

[0005] Soldering itself, for example using SnPbAg, has a disadvantage for silicon heterojunction cells. The solder may require heat treatment at temperatures above or equal to 200°C. Some cell types, such as silicon heterojunction cells, can be damaged at these temperatures. Alloys containing Bi can allow soldering at temperatures below 200°C without damaging the cell. On the other hand, less ductile Bi-based alloys can lead to unreliable solder joints due to brittleness.

[0006] To overcome this problem, soldering can be replaced by gluing. The bonding is achieved, for example, using an electrically conductive adhesive, known as "ECA" for "Electrical Conductive Adhesive" in English. This is a material in the form of a paste, composed of metallic elements (such as silver or copper particles) dispersed in a polymer or silicone-based matrix. The electrically conductive adhesive (which we will simply call adhesive) has the particularity of being able to crosslink (in other words harden) under the effect of a temperature below 200 °C. The adhesive allows electrical and mechanical contact to be made between the solar cells and the conductive wires. The adhesive is also more flexible than welds. It therefore allows for more reliable interconnections. Furthermore, the adhesive can also adhere to non-metallized areas. This avoids the need for large-area metallizations such as busbars, as electrical contact can be achieved by small metallized areas, for example, equal to the surface area of ​​a collection conductor.

[0007] An adhesive can be applied to a photovoltaic cell by screen printing. This process involves spreading the adhesive onto a cell by passing the adhesive through a mask. The mask corresponds, for example, to a negative pattern. It can be a mesh (or a canvas) covered with a resin that locally seals the mesh. The mask can also be a stencil composed of a thin metal plate open locally at the location where the adhesive is to be applied.

[0008] In a process for bonding conductive tapes or wires to a cell, the adhesive portions are deposited on the cell and the conductive tapes or wires are then deposited on the adhesive portions. In order to achieve the bonding, the adhesive portions are sized to compensate for an alignment error of the conductive tapes or wires when they come into contact. For example, for a thin wire, having a diameter of less than 500 pm, for example 350 pm, the adhesive portions will have a width of approximately 800 pm (thus offering 225 pm of alignment error on each side of the wire).This results in two major disadvantages on the one hand: a shadow cast wider than the wire, especially since this flat metallized surface leads to an effective shading of 100% of its width, whereas the cylindrical wire has an effective shading corresponding to 70% of its width (due to reflections on its curved surface), which reduces the electrical power (or production efficiency) of the module; and on the other hand, excessive consumption of adhesive.

[0009] The field of photovoltaic energy production aims to reduce the consumption of particles needed to make adhesives, particularly silver particles, which are used to make adhesives. In 2022, the global photovoltaic industry will consume more than 10% of the silver produced worldwide, with annual electricity production of around 100 GW. Current silver consumption per unit of electrical power is estimated at between 25 mg and 40 mg of silver per Watt.

[0010] This consumption is expected to decrease in the coming years. However, assuming a silver consumption of 5 mg / W by 2035 and an annual electricity production of 3 TW, estimates indicate that the photovoltaic industry will then consume more than 50% of the silver produced worldwide. Special efforts are therefore being made to further reduce silver consumption per unit of electrical power with a target of approximately 2 mg / W by 2035.

[0011] Silver is used to make adhesives and also to form collecting electrodes on the surface of photovoltaic cells. Adhesives have high silver contents, for example around 50% (by weight). Electrodes have even higher silver contents, exceeding 90% silver for metallizations of heterojunction cells using so-called "low temperature" pastes (annealed at a temperature of around 200 °C instead of temperatures above 700 °C).

[0012] There is therefore a need to reduce the amount of paste used for metallization as well as the amount of electrically conductive adhesive consumed for the interconnection of photovoltaic cells. SUMMARY OF THE INVENTION

[0013] The invention addresses the aforementioned problem in that it proposes a method for bonding at least one interconnection element to a first photovoltaic cell, the method successively comprising the following steps: depositing a first electrically conductive adhesive film on each interconnection element; depositing each interconnection element on the first photovoltaic cell, the first electrically conductive adhesive film of each interconnection element being arranged in contact with the first photovoltaic cell.

[0014] The process eliminates the need to size portions of electrically conductive adhesive (also referred to simply as "adhesive") large enough to compensate for misalignment of the interconnect element. This results in reduced adhesive consumption. (and therefore a reduction in the silver consumption required to develop the adhesive). In addition, the shadow cast on the cell is reduced. The invention offers an additional advantage in that it also eliminates the adhesive screen printing equipment required to deposit the adhesive on the photovoltaic cells, which simplifies the interconnection of the photovoltaic cells and also reduces the useful surface area (in terms of equipment surface area) required to interconnect the cells. This also results in a reduction in the cost corresponding to the interconnection of the cells, which is also reflected in the manufacturing cost of a photovoltaic module.

[0015] Preferably, the first cell comprises collection electrodes parallel to each other, each interconnection element being deposited non-parallel to the collection electrodes, the first electrically conductive adhesive film of each interconnection element being arranged in contact with at least one of the collection electrodes of the first photovoltaic cell.

[0016] Preferably, each collection electrode has a constant width. The width of a collection electrode is measured parallel to a plane in which the first photovoltaic cell extends. It corresponds, for example, to the smallest measured dimension.

[0017] Preferably, for each interconnection element, the first electrically conductive adhesive film has a width less than or equal to the width of said interconnection element and preferably less than or equal to half the width of said interconnection element. The width of the first electrically conductive adhesive film and the width of said interconnection element are measured parallel to the plane in which the first photovoltaic cell extends and perpendicular to a direction in which said interconnection element extends.

[0018] Preferably, for each interconnection element, the first electrically conductive adhesive film extends over a first length of the interconnection element, preferably between 30% and 50% of the total length of each interconnection element.

[0019] The first electrically conductive adhesive film is preferably continuous over the entire first length.

[0020] The first electrically conductive adhesive film is advantageously discontinuous, the first electrically conductive adhesive film comprising portions of electrically conductive adhesive distributed throughout the first length of the interconnection element.

[0021] Advantageously, for each interconnection element, the portions of the first electrically conductive adhesive are distributed over the entire first length so that each portion of electrically conductive adhesive is in contact with at least one of the collection electrodes of the first photovoltaic cell and preferably with only one of the collection electrodes of the first photovoltaic cell.

[0022] Advantageously, for each interconnection element, the portions of the first electrically conductive adhesive are distributed over the entire first length so that each collection electrode of the first photovoltaic cell is in contact with at least one portion of electrically conductive adhesive.

[0023] Advantageously, the method comprises a step of arranging each interconnection element so that the first electrically conductive adhesive film faces the first photovoltaic cell, the step of depositing the first electrically conductive adhesive film being preferably carried out simultaneously with this arrangement step.

[0024] Preferably, the method comprises the following additional steps: depositing a second electrically conductive adhesive film on each interconnection element, the second film being distant from the first film; depositing each interconnection element on a second photovoltaic cell, the second electrically conductive adhesive film of each interconnection element being arranged in contact with the second photovoltaic cell.

[0025] Preferably, the deposition of the second electrically conductive adhesive film is carried out simultaneously with the deposition of the first electrically conductive adhesive film.

[0026] The invention also relates to a device for bonding at least one interconnection element to a first photovoltaic cell comprising: at least one electrically conductive adhesive applicator; means for gripping and guiding the interconnection element; means for supporting the first photovoltaic cell; and means configured to carry out the steps of the bonding method according to the invention.

[0027] The invention further relates to a computer program comprising instructions which cause the device according to the invention to execute the steps of the method according to the invention.

[0028] The invention also relates to a computer-readable medium on which the aforementioned computer program is recorded.

[0029] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0030] The figures are presented for information purposes only and in no way limit the invention. Unless otherwise specified, the same element appearing in different figures has a single reference.

[0031] [Fig. 1] schematically represents an embodiment of a bonding method according to the invention.

[0032] [Fig. 2a] and [Fig. 2b] schematically represent a first embodiment of an interconnection element resulting from one of the steps of the method of [Fig. 1].

[0033] [Fig. 3] schematically represents a second embodiment of the interconnection element resulting from one of the steps of the method of [Fig. 1],

[0034] [Fig. 4] schematically represents a first embodiment of a bonding device making it possible to implement the method of [Fig. 1],

[0035] [Fig. 5], [Fig. 6], [Fig. 7] and [Fig. 8] partially represent second, third, fourth and fifth embodiments of the gluing device.

[0036] [Fig. 9] represents an embodiment of a photovoltaic cell which can be used by the method of [Fig. 1],

[0037] [Fig. 10] schematically represents a first interconnection mode resulting from one of the steps of the process of [Fig. 1],

[0038] [Fig. 11] schematically represents a second interconnection mode resulting from one of the steps of the process of [Fig. 1], DETAILED DESCRIPTION

[0039] [Fig. 1] illustrates a first embodiment of an interconnection method PROC according to the invention. The method PROC consists of bonding at least one interconnection element INTR to a first photovoltaic cell CELL1. For this, the method PROC comprises the following steps, carried out successively: depositing PROC1 a first film F1 of electrically conductive adhesive on each interconnection element INTR; and then depositing PROC5 each interconnection element INTR, comprising a first film F1 of adhesive, on the first photovoltaic cell CELL1, the first film F1 of electrically conductive adhesive of each interconnection element INTR being arranged in contact with the first photovoltaic cell CELL1.

[0040] To simplify the description and unless otherwise stated, electrically conductive adhesive will simply be referred to as “adhesive”.

[0041] Thanks to the adhesive first deposited on each INTR interconnection element, there is no longer any constraint on the lateral alignment of the interconnection elements.

[0042] Furthermore, since it is no longer necessary to apply large amounts of adhesive to achieve bonding, adhesive consumption is reduced, and with it the consumption of conductive material such as silver. The shadow cast by the adhesive (which is opaque) is also reduced.

[0043] [Fig. 2a] and [Fig. 2b] schematically represent an embodiment of the interconnection element INTR obtained at the end of the deposition step PROC1 of the adhesive film F1. The interconnection element INTR represented is in wire form. The interconnection element can actually be a conductive wire or a conductive strip. Whether it is a wire or a strip, the interconnection element INTR can also be covered with a thin layer of conductive alloy, for example silver or tin. The interconnection element may also have a cross-section that is neither circular nor rectangular, for example oval or triangular.

[0044] In the illustrated example, the interconnection element INTR is a conductive wire comprising two parts each extending in the X direction, separated by an ELB elbow. Such an interconnection element can be used to interconnect two photovoltaic cells together, while providing a small space between the cells (in particular thanks to the ELB elbow). In the illustrated example, the interconnection element INTR has a circular section of diameter D.

[0045] The first adhesive film F1 extends over a portion of the surface of the interconnection element. In this case, it extends under the interconnection element INTR. It extends over a first length L1 along said element INTR (measured here in the X direction). The first film F1 may extend from one end of the element INTR and in the direction of the elbow ELB. In the example illustrated, it is two to ten millimeters away from said end and extends, in the X direction, in the direction of the elbow ELB.

[0046] The first length L1 is preferably less than 50% of the total length L of the interconnection element INTR. In one embodiment, the interconnection element INTR may not be cut before the deposition of the first film F1. The total length L of the interconnection element INTR to be considered is then advantageously the expected length of said interconnection element INTR. The first length L1 is preferably greater than 30% of the total length L of the interconnection element INTR.

[0047] [Fig. 2b] shows that the first film F1 extends over a part of the radial surface of the interconnection element INTR. This surface is for example delimited by a plane angle ai. The surface S1 of the interconnection element INTR over which the first film F1 extends is therefore equal to

[0048] [Math. 1] SI = LI xax D / 2

[0049] In a limiting case, the first film F1 of adhesive could coat the entire surface of the interconnection element INTR (over the first length L1). This would be a plane angle a ± = 2n. However, there would be little point in doing this. The first cell CELL1 can only be connected along a tangent to the surface of the INTR element. A large part of the adhesive would therefore not participate in the connection and would therefore be used unnecessarily. It is desirable that the first film F1 extends over a surface of the INTR element having the angle a ± < n and preferably the plane angle «i < TT / 2. In the latter case, the surface of the interconnection element INTR on which the first film F1 extends is therefore equal to L1 x nD / 4.

[0050] The first film F1 can have a thickness H 1 which can be between 10 pm and 50 pm. The first film F1 has a width W1 (taking into account its thickness H1), measured along the Y direction. It is preferable that the width W1 is sized so as to provide a surface S1 large enough to obtain maximum bonding, while avoiding increasing the effective shading of the interconnection element INTR on the first cell CELL1. Indeed, the adhesive may be slightly transparent or even opaque. It is therefore preferable that W1 < D. The width W1 can be between 15%xD and 100%xD. For example, for a wire interconnection element, with a diameter D = 350 pm, the width W1 of the film F1 is between 50 pm and 350 pm, ideally between 100 and 175 pm. According to another example, for a wire interconnection element, of diameter D = 500 pm, the width W1 of the film F1 is between 150 pm and 500 pm. According to a third example, for a diameter of D = 250 pm, the width W1 of the film F1 can be between 60 pm and 125 pm.

[0051] Preferably, the width W1 is such that W1 < D / 2.

[0052] The reduced width W1 of the first film F1 is also applicable in the case of a ribbon-type INTR element, following the same teachings, considering that the diameter of a circular conductor corresponds to the width of the latter. Thus, It is therefore preferable that the width W1 of the first film F1 is less than or equal to the width of the INTR element, whether it is of the wire or ribbon type. The reduction of shading (in case of overflow on the sides during bonding) and the reduction of the quantity of adhesive used also implies that the width W1 of the first film F1 is less than half the width of the INTR element, whether it is of the wire or ribbon type.

[0053] The width W1 of the first film F1 can take into account the viscosity of the adhesive. Indeed, the latter, once deposited on the interconnection element, undergoes competition between capillary forces and gravity. It therefore does not necessarily show a constant thickness H1. It can, for example, form a drop directly above the INTR element, reducing the effective width W1 of the adhesive. The contact of the drop on a SURF surface can also be made over a width W2, measured parallel to this surface, which can be smaller than the width W1 of the film F1. It is therefore preferable that the deposition of the first F1 takes into account the width W2 in order to determine the width W1.

[0054] The width W1 of the first film F1 (and therefore the calculation of the corresponding plane angle) can also take into account the phenomenon of light reflection on the interconnection element INTR, in particular when the latter is wire-like. Indeed, the effective shading can be reduced thanks to these reflections. It is therefore advantageous to favor reflections. However, the presence of adhesive on the sides of the interconnection element INTR could limit the reflections. This is the reason why the width W1 (and for example the corresponding plane angle) is preferably such that it limits the presence of adhesive on the sides of the interconnection element.

[0055] The INTR interconnection element can also be a conductive strip. By strip, we mean an element having a rectangular section. In this case, the adhesive is advantageously deposited on one of the faces of the strip with a rectangular section. The width of the first film F1, measured in a direction transverse to the INTR element, is therefore preferably less than or equal to the width of the INTR interconnection element. In practice, it is easier to deposit the adhesive over the entire width so as not to have to manage alignment when depositing said adhesive. The width of the first film F1 is therefore equal to the width of the strip, or even slightly greater if the adhesive has slightly overflowed onto the sides of the strip.

[0056] [Fig. 3] represents a variant of the embodiment of the interconnection element INTR. In [Fig. 2a] and [Fig. 2b], the first film F1 is continuous over the entire first length L1. In the variant of [Fig. 3], the first film F1 is discontinuous. It comprises, for example, portions P1, P2, P3, PN distributed over the entire first length L1. This mode could, for example, be preferred in the case where the first film F1 extends over the entire width of a ribbon, in order to limit the surface area of ​​the adhesive.

[0057] These portions may have respective lengths of between 0.2 mm and 1.5 mm (measured according to the direction in which the element extends, i.e. along the X direction in the figures). In a particular case, the portions P1, P2, P3, PN can be distributed according to a constant LP pitch, for example between 0.5 mm and 3 mm. The LP pitch is preferably defined from a pitch according to which collection conductors, arranged on an interconnection surface, are distributed. Short portions can make it possible to connect each collection conductor while reducing the quantity of adhesive used. On the other hand, they can induce an increase in the constraint in terms of alignment precision in the direction of the interconnection elements (when these are deposited on said collection conductors). A variant then consists of making longer adhesive portions distributed according to a larger plane in order to connect the collection conductors in groups, for example two by two or three, or even more.The collection conductors may also be connected together, for example two by two or three by three, by tracks extending, with the collection conductors, on the interconnection surface (the tracks are for example manufactured at the same time as the collection conductors). The portions of the first film F1 may then be sized and distributed to connect said tracks. The portions of the first film F1 may also be sized and distributed to connect a collection conductor in each group of collection conductors connected by a track.

[0058] The amount of adhesive used can also be minimized by forming a first film, continuous or discontinuous, with a low thickness H1. It can be between 5 μm and 20 μm.

[0059] [Fig. 4] schematically represents an interconnection device DISP making it possible to implement the method PROC for bonding at least one interconnection element INTR onto a first photovoltaic cell CELL1. The illustrated DISP device comprises: two adhesive applicators APP1, APP2; and specific means PREH, GD, CONV making it possible to deposit the first film F1 and to arrange the interconnection element INTR and the first photovoltaic cell CELL1 in order to be able to carry out the depositing of the interconnection element INTR onto the first cell CELL1.

[0060] The illustrated DISP device also comprises a complementary means, such as a CTRL controller, configured to implement at least the aforementioned means of the DISP device. It is configured in particular to allow the various stages of the PROC process to be carried out.

[0061] The implementation of the deposition step PROC1 of the adhesive film F1 on each INTR interconnection element will be described using the DISP device. Unless otherwise stated, the description relates to a single INTR interconnection element. The teachings described below are however applicable to several INTR interconnection elements processed for example in parallel and / or simultaneously or sequentially.

[0062] The DISP device may comprise at least one reel on which the INTR interconnection element, in wire or ribbon, is wound. The DISP device may also comprise a TNSR mechanism for tensioning the INTR interconnection element which makes it possible to unwind the INTR interconnection elements at a continuous and controlled speed. In addition, the TNSR tensioning mechanism makes it possible to control the tensile force applied to the INTR interconnection element so as not to weaken it or at least to control its deformation.

[0063] The interconnecting element INTR is advanced until its end reaches a gripping means PREH. This is for example a gripper configured to grip one end of the interconnecting element INTR. A roller ROLL can be used to align the interconnecting element INTR so that it reaches the gripping means PREH without hindrance. The roller ROLL can also be positioned between the two applicators APP1, APP2 to provide a surface at a predetermined position on which the interconnecting element INTR rests when depositing the adhesive.

[0064] The gripping means PREH is also configured to pull the end of the interconnection element INTR between the two applicators APP1, APP2. It can also be configured to bring the interconnection element INTR into contact with one of the two applicators APP1, APP2, or even both applicators APP1, APP2, in turn. Guiding means GD, comprising one or more guides, can make it possible to maintain the alignment of the interconnection element INTR so that it passes in front of the first applicator APP1, at a predefined position.

[0065] [Fig. 5] illustrates an example of duplicators APP1, APP2, configured to apply the adhesive to the interconnection element INTR. They include for example inking rollers R1, R2 which are applied to the interconnection element INTR. Each roller R1, R2 is connected to a reservoir RES1, RES2 of adhesive and thus deposits a layer of adhesive when it rolls along the interconnection element INTR. Thus, when the element INTR is applied against the inking rollers R1, R2, adhesive is transferred to the element INTR. The inking rollers R1, R2 can be moved along the interconnection element INTR (the interconnection element INTR remaining fixed) in order to deposit the film on the interconnection element INTR. The interconnection element INTR can otherwise be translated against the inking rollers R1, R2 in order to transfer the adhesive and form the adhesive films.

[0066] Alternatively, the applicators APP1, APP2 may comprise an adhesive-laden area, which may be called a "scraper", against which the interconnecting element INTR rubs. This area thus acts in a similar manner to a brush which deposits a constant layer of adhesive.

[0067] The applicators APP1, APP2 may also include nozzles through which the adhesive can flow. Alternatively, these nozzles may be configured to spray the adhesive onto the interconnection element INTR, in the manner of inkjet printing.

[0068] The applicators APP1, APP2 are preferably configured to deposit the first and second films F1, F2 at predetermined positions of the interconnection element INTR and at predetermined plane angles. For example, in [Fig. 2a], [Fig. 2b], the first film F1 is arranged under the interconnection element INTR and at a predetermined plane angle. To deposit the first film F1 in this manner, the first applicator APP1 is for example positioned under the interconnection element INTR when the gripping means PREH moves it. Thus, when the interconnection element INTR is translated by the gripping means PREH in front of the first applicator APP1 and for example against it, the first film F1 is formed along the interconnection element INTR. When the interconnecting element INTR is translated by a first length L1, the first applicator APP1 is withdrawn and / or the flow of adhesive is stopped.

[0069] In an alternative embodiment, making it possible to form the first discontinuous film F1 of [Fig. 3], the first applicator APP1 can be brought into intermittent contact with the interconnection element INTR as the latter passes in front of the applicator APP1. Alternatively, the flow of adhesive exiting the nozzle of the applicator APP1 may be intermittent, rather than effecting a movement of the applicator APP1 itself. The second discontinuous film F2 may be formed in the same manner with the second applicator APP2.

[0070] [Fig. 6] illustrates an example of the DISP device in which the ROLL roller is arranged between the two applicators APP1, APP2. The interconnection element INTR can thus rest on a portion of the ROLL roller. The interconnection element INTR can, for example, move in the Z direction and then change direction at the level thanks to the ROLL roller to then move in the X direction. The ROLL roller makes it possible to arrange the interconnection element INTR at the correct distance from the applicators APP1, APP2. It can also make it possible to control the tension on the interconnection element INTR by applying a torque to said INTR element.

[0071] [Fig. 7] and [Fig. 8] illustrate an embodiment of the PREH gripping means. According to this example, it is configured to grip five INTR interconnection elements in parallel. It can grip and hold the INTR elements by applying a slight depression by means of a CNL pneumatic channel. The PREH gripping means can also comprise a robotic arm capable of moving the INTR elements and bringing them into contact with the first applicator APP1 (case of [Fig. 7]) and / or the second applicators APP2 (case of [Fig. 8]).

[0072] In [Fig. 7], the first applicator APP1 is, for example, a bath of ECA adhesive in which a portion of the INTR elements held by the gripping means PREH are bathed. Thus, calibrating the depth of the bath, for example 80 μm, makes it possible to deposit a controlled thickness of ECA adhesive without, however, requiring fine control of the height of the gripping means PREH. Indeed, the interconnection elements INTR are brought into contact with the bath and, for example, pressed against the bottom of the bath. The quantity of ECA adhesive deposited is then proportional to the depth of the bath. The adhesive bath can be placed on a vertically flexible FM support (for example a foam element) to limit the deformation of the INTR elements during contact. In [Fig. 8], the second applicator APP2 is, for example, an area loaded with ECA adhesive, called a “buffer”, against which the INTR elements are pressed by the gripping means PREH.The stamp can also be placed on a vertically flexible FM holder.

[0073] The PROC method, as illustrated by [Fig. 1], preferably comprises a step PROC3 of arranging each interconnection element INTR so that the first adhesive film F1 faces the first photovoltaic cell CELL1. This step PROC3 of arranging occurs before the step PROC5 of depositing the interconnection element INTR on the first cell CELL1.

[0074] The gripping means PREH and / or the guiding means GD make it possible, for example, to arrange the interconnection element INTR. The device DISP may also comprise support means CONV. This is, for example, a conveyor on which the first cell CELL1 is positioned.

[0075] The gripping means PREH, the guiding means GD and the supporting means CONV make it possible to arrange the interconnection element INTR and the first cell CELL1 relative to each other. The gripping means PREH pulls, for example, the interconnection element INTR above the first cell CELL1, the first film F1 being arranged directly above the first cell CELL1. In the examples illustrated by [Fig. 2a], [Fig. 2b] and [Fig. 3], the first film F1 is arranged under the interconnection element INTR. The conveyor CONV is then advantageously configured to arrange the first cell CELL1 under the interconnection element INTR.

[0076] The depositing step PROC1 of the first adhesive film F1 can be carried out before the arrangement step PROC3. However, it is advantageous for the depositing PROC1 of the first film F1 to be carried out simultaneously with this arrangement step PROC3. Indeed, the arrangement of the interconnection element INTR can comprise the translation of the interconnection element INTR, by the gripping means PREH, towards the first cell CELL1. Therefore, it is advantageous to take advantage of this translation to produce, by means of the first applicator APP1, the first film F1. The duration of mobilization of the interconnection element to produce the first film is thus included in the duration of the arrangement step PROC3.

[0077] Preferably, the PROC process is carried out so that the different steps can be carried out while the interconnection element INTR is in continuous translation and even more preferably at constant speed. For example, to meet industrial rate requirements, the translation speed of the interconnection element INTR can be between 200 mm / s and 1000 mm / s. The steps of depositing PROC1 of the first film F1, of arranging PROC3 and of depositing of the INTR element on the cell CELL1 are then advantageously configured to be carried out with the translation at constant speed of the interconnection element INTR. For example, during the deposit PROC5 of the interconnection element INTR on the first cell CELL1, the conveyor CONV and the gripping means PREH move the first cell CELL1 and the interconnection element INTR with a constant speed (in the direction X in the figures).

[0078] The PROC method may also comprise a cutting step PROC4 of each interconnection element INTR. This step may take place before or after the deposition of the first film F1. It may be easier to cut the interconnection elements INTR when the deposition of the first film F1 is carried out using a gripping means PREH and an applicator as illustrated by [Fig. 7], or even by [Fig. 8],

[0079] The PROC4 cutting is preferably carried out before the deposition of the INTR interconnection elements on the first cell CELL1. However, it can be carried out at a later stage of the PROC process, for example after the deposition of the INTR interconnection elements on the first cell CELL1. However, in the latter case, a small part of the INTR interconnection element may protrude from the CELL1 which, in the long term, tends to increase the consumption of material to form the INTR interconnection element.

[0080] The device DISP can therefore comprise a cutting means CUTR of the interconnection element INTR, arranged upstream of the applicators APP1, APP2 (depending on the direction of movement of the element). This cutting means CUTR is for example a blade and counter-blade system similar to a guillotine. It makes it possible to cut an interconnection element to a predetermined length. When several interconnection elements INTR are cut at the same time, it is preferable for the blade and counter-blade to close in parallel in order to cut all the INTR elements at the same time without translating them so as not to misalign them. The cutting of the interconnection element INTR occurs before or after the deposition of the first film F1 and preferably before the deposition of the interconnection element INTR on the first cell CELL1.

[0081] In order to carry out the depositing step PROC5 of the interconnection element INTR on the first photovoltaic cell CELL1, the gripping means PREH of the The DISP device may be configured to bring the interconnection element into contact with the cell CELL1. The DISP device may also comprise means configured to apply pressure to the interconnection element INTR in order to bring it into contact with the first cell CELL1 and also to achieve adhesion of the first film F1 to said cell CELL1.

[0082] [Fig. 9] shows an embodiment of the first photovoltaic cell CELL1. The first cell CELL1 is for example a silicon heterojunction photovoltaic cell. The first cell CELL1 comprises a first face FAV and a second face FAR, opposite the first face FAV. The first face FAV is for example the so-called "front" face of the first cell CELL1. That is to say the face intended to be exposed to electromagnetic radiation. In this embodiment, the first cell CELL1 comprises collection electrodes FGR, also called collection fingers. These are conductive tracks extending over at least one of the FAV faces of the first cell CELL1. These collection electrodes FGR are intended to collect the currents from the photovoltaic cell when the latter is exposed to electromagnetic radiation. The collection electrodes FGR are advantageously parallel to each other.They extend preferentially over the entire surface of the first cell CELL1.

[0083] An FGR collection electrode advantageously has a width, measured in the plane of the cell CELL1 , of between 35 pm and 45 pm. An FGR collection electrode may also have a height, measured perpendicular to the plane of the cell CELL1 , of between 12 pm and 15 pm.

[0084] The FGR collection electrodes can be distributed on the first cell CELL1 with a constant pitch, between 0.5 mm and 3 mm, for example 1.5 mm.

[0085] The FGR collection electrodes preferably have a constant width. Indeed, the PROC process makes it possible to bond an INTR interconnection element onto the first cell CELL1 without resorting to additional conductive elements, such as busbars. The first cell CELL1 is therefore advantageously free of any busbar. It can be called "busbarless" in English or "BB0". The first cell CELL1 thus only has FGR collection electrodes on the face intended to accommodate the interconnection element. FGR collection electrodes also do not need to have larger cross-sections. Since FGR collection electrodes can also be made of silver, this results in a reduction in the silver used.

[0086] [Fig. 10] schematically represents an interconnection element INTR deposited on a first cell CELL1. This is the outcome of the step PROC5 of depositing the interconnection element INTR on the first cell CELL1. The first cell CELL1 is arranged so that its first face FAV is oriented in the Z direction. It is in particular arranged parallel to the plane {X; Y}. The first face FAV comprises collection electrodes FGR which extend in the Y direction. The interconnection element INTR extends mainly in the X direction, i.e. perpendicular to the collection electrodes FGR. A first film F1 of adhesive, here continuous, is arranged under the interconnection element INTR and is in contact with the first face FAV of the first cell CELL1 and the collection electrodes FGR. The interconnection element INTR extends at least partly over the first cell CELL1.In the example shown, it also extends beyond cell CELL1 (that is, it intersects an edge of cell CELL1 ), so that it can interconnect another cell.

[0087] In this example, the interconnection element INTR connects, by means of the first film F1, at least one collection electrode FGR. In this way the circulation of electric currents is established. It is preferable for the interconnection element INTR to connect several collection electrodes FGR in order to ensure circulation of the collected electric currents with a low effective resistance. For this, the interconnection element INTR preferably extends non-parallel to the collection electrodes FGR, as in this specific case where it extends perpendicular to the collection electrodes FGR.

[0088] When the first film F1 is continuous over the entire first length L1 of an interconnection element INTR, the interconnection element INTR is deposited on at least one collection electrode FGR, the first film F1 of adhesive being in contact with at least one electrode FGR and preferably all the electrodes FGR.

[0089] [Fig. 11] also schematically represents an interconnection element INTR deposited on a first cell CELL1. Unlike [Fig. 10], the first film F1 is discontinuous. It includes in particular the portions P1, P2, P3, PN as described previously. In this example, the distribution of the portions P1, P2, P3, PN of the first film F1 corresponds to the arrangement of the collection electrodes FGR on the first cell CELL1. Each portion P1, P2, P3, PN of the first film F1 is then in contact with at least one collection electrode FGR. When the collection electrodes FGR are distributed regularly, according to a constant pitch DFGR, the portions of the first film F1 can also be distributed regularly, the pitch LP of the portions P1, P2, P3, PN along the element INTR then being equal to the pitch DFGR of the collection electrodes FGR. In a development, each portion P1, P2, P3, PN of the first film F1 is in contact with a plurality of collection electrodes FGR, for example 2 or 3 electrodes. The portions P1, P2, P3, PN are preferentially in contact with a small number of electrodes, for example less than 10.

[0090] A first discontinuous film F1 makes it possible to further reduce the consumption of adhesive. On the other hand, it can impose a stronger alignment constraint on the interconnection element INTR than a first continuous film F1. The arrangement step PROC3 of the interconnection element INTR is then implemented to take into account the distribution of the portions of the first film F1 and the distribution of the collection electrodes FGR on the first cell CELL1. The interconnection element INTR is then arranged so that each portion of the first film F1 is directly above at least one collection electrode FGR. This alignment is advantageously maintained during the deposition step PROC5 of the element on the cell CELL1.

[0091] A continuous first film F1 increases the consumption of adhesive, compared to a discontinuous film, on the other hand, it reduces the alignment constraint on the first cell CELL1. It is important to note that even if continuous, the first film F1 makes it possible to reduce the quantity of adhesive required compared to an adhesive film according to the prior art, initially deposited on the photovoltaic cell, for example by screen printing, and having a width large enough to allow a lateral alignment error (in [Fig. 10] and [Fig. 11], this lateral error would be directed in the Y direction if the interconnection element according to the prior art extended in the X direction).

[0092] The PROC process advantageously allows several INTR interconnection elements to be bonded, for example at least three INTR interconnection elements up to more than eight INTR elements. For example, it is possible to bond twelve or sixteen INTR interconnection elements on the first cell CELL1. The steps and means described above are advantageously configured to bond the INTR interconnection elements simultaneously. For example, the gripping means PREH can grip all the INTR interconnection elements at once. The applicator APP1 can also be configured to form a first film F1 on all the INTR elements at the same time. It comprises, for example, as many nozzles as there are INTR interconnection elements to be treated simultaneously.

[0093] In addition to what has just been described, the method PROC can also provide for the bonding of at least one interconnection element INTR as described with a second photovoltaic cell CELL2. For this, the method PROC comprises the following additional steps: depositing PROC2 a second film F2 of adhesive on each interconnection element INTR, the second film F2 being distant from the first film F1, for example, by more than 5 mm; and depositing PROC6 each interconnection element INTR comprising a second film F1 of adhesive on a second photovoltaic cell CELL2, the second electrically conductive film F2 of adhesive of each interconnection element INTR being in contact with the second photovoltaic cell CELL2.

[0094] [Fig. 2a] and [Fig. 3] show two examples of embodiments of the second film F2. In these two examples, the second film F2 extends over a second length L2 of the interconnection element INTR from a second end, opposite the first end from which the first film F1 extends. The second film F1 may extend from the second end or be distant from this second end. In the same way as the first film F1, the second length L2 is advantageously between 30% and 50% of the total length L of the interconnection element INTR.

[0095] It is important to note that the second film F2 can be deposited before the second end is created, i.e. before the interconnection element INTR is cut, for example by means of the cutting means CUTR. The second film F2 can be arranged on the interconnection element INTR taking into account the second end or at least its intended position.

[0096] In the embodiment of [Fig. 2a] and [Fig. 3], the second film F2 extends over the interconnection element INTR while the first film F1 extends under the interconnection element. According to a variant, the first and second films F1, F2 could extend on the same side of the interconnection element INTR, for example above or below the interconnection element INTR. This variant is particularly relevant for interconnecting cells with interdigitated back contacts known as "IBCs". Indeed, all the cells are connected by their rear surfaces. It is also advisable, in order to reduce the risk of short-circuiting between the interdigitated contacts, to form films F1, F2 of discontinuous adhesive. The portions P1, P2, P3, PN of the films F1, F2 are then arranged so as to only connect the contacts of the same polarity.It may also be envisaged to deposit, between two consecutive portions P1, P2, P3, PN, pads of insulating material, for example made of an insulating adhesive. These insulating pads then separate the interconnection element INTR from the contacts of a different polarity.

[0097] The second film F2 can be deposited by means of the second applicator APP2. For this purpose, the second applicator APP2 can have the same characteristics as the first applicator APP1. The second applicator APP2 can be oriented opposite to the first applicator APP1. The gripping means PREH and the guiding means GD are then also configured so that the second applicator APP2 can be applied against the interconnection element INTR.

[0098] The two applicators APP1, APP2 can be directly above each other. In this case, the first application APP1 forms the first adhesive film F1 before the second adhesive film F2. Advantageously, the two applicators APP1, APP2 can have a relative distance from each other so that the two adhesive films F1, F2 are deposited simultaneously. This results in a time saving allowing an industrial rate to be maintained.

[0099] The device DISP may also comprise a complementary support means for arranging the second cell CELL2 relative to the interconnection element INTR. This means is for example configured to deposit the second cell on the interconnection elements INTR and in particular on the second adhesive film F2. The second adhesive film F2 may also be continuous (illustrated by [Fig. 2a]) or discontinuous (illustrated by [Fig. 3]). When the second cell CELL2 also has collection electrodes FGR, the complementary arrangement means can also be configured to deposit the second cell CELL2 on the interconnection element INTR so that each portion of the second film F2 is in contact with a collection electrode FGR.

[0100] The DISP device may also comprise a means for shaping SHPR of the interconnection element INTR, configured to form the ELB elbow as illustrated in [Fig. 2a],

[0101] According to an advantageous implementation, the method PROC also comprises a step PROC7 of heat treatment of each first adhesive film F1. The heat treatment is advantageously carried out to crosslink the first film F1 (in other words to solidify the adhesive of the first film F1). In this way, the mechanical and electrical connection between the interconnection elements INTR and the first cell CELL1 is fixed. More preferably, the heat treatment step PROC7 is also configured to treat each second adhesive film F2. For this, the device DISP may comprise a treatment means, such as an oven. The oven may consist of heating plates and / or infrared lamps. The assembly comprising the interconnection element INTR deposited on the first cell CELL1 and possibly deposited on the second cell CELL2, is placed in the treatment means.The heat treatment is then carried out by heating the assembly while controlling the average temperature of the assembly and in particular of the cells CELL1, CELL2. The temperature is advantageously less than 200°C and preferably less than 175°C. The average temperature is for example between 120°C and 200°C and preferably between 150°C and 175°C. The duration of the heat treatment depends on the nature of the adhesive used and the average treatment temperature. It may however be between 5 s and 30 s. The heat treatment is advantageously carried out in such a way as to allow the treatment to be carried out while maintaining a translation of the interconnection element. In this way, the bonding of the interconnection element on the cell(s) is carried out continuously.

Claims

CLAIMS

1. Method (PROC) of bonding at least one interconnection element (INTR) to a first photovoltaic cell (CELL1), the method successively comprising the following steps: - depositing (PROC1) a first film (F1) of electrically conductive adhesive on each interconnection element (INTR); - depositing (PROC5) each interconnection element (INTR) on the first photovoltaic cell (CELL1), the first film (F1) of electrically conductive adhesive of each interconnection element (INTR) being arranged in contact with the first photovoltaic cell (CELL1), in which the first cell (CELL1) comprises collection electrodes (FGR) parallel to each other, each interconnection element (INTR) being deposited non-parallel to the collection electrodes (FGR), the first film (F1) of electrically conductive adhesive of each interconnection element (INTR) being arranged in contact with at least one of the collection electrodes (FGR) of the first photovoltaic cell (CELL1), and in which, for each interconnection element (INTR), the first film (F1) of electrically conductive adhesive extends over a first length (L1) of the interconnection element (INTR) and is discontinuous,the first film (F1) of electrically conductive adhesive comprising portions (P1, P2, P3, PN) of electrically conductive adhesive distributed over the entire first length (L1) of the interconnection element (INTR) and in which for each interconnection element (INTR), the portions (P1, P2, P3, PN) of the first (F1) of electrically conductive adhesive are distributed over the entire first length (L1) so that each collection electrode (FGR) of the first photovoltaic cell (CELL1) is in contact with at least one portion (P1, P2, P3, PN) of electrically conductive adhesive.,

2. Method (PROC) according to the preceding claim, in which, for each interconnection element (INTR), the portions (P1, P2, P3, PN) of the first electrically conductive adhesive are distributed over the entire first length (L1) so that each portion (P1, P2, P3, PN) of electrically conductive adhesive conductor is in contact with only one of the collection electrodes (FGR) of the first photovoltaic cell (CELL1).

3. Method (PROC) according to one of the preceding claims, in which each interconnection element (INTR) has two ends, and in which, for each interconnection element (INTR), the first film (F1) is distant from each end.

4. Method (PROC) according to one of the preceding claims, in which, for each interconnection element (INTR), the first film (F1) of electrically conductive adhesive has a width (W1) less than or equal to the width (D) of said interconnection element (INTR).

5. Method (PROC) according to the preceding claim, in which, for each interconnection element (INTR), the first electrically conductive adhesive film (F1) has a width (W1) less than or equal to half the width (D) of said interconnection element (INTR).

6. Method (PROC) according to one of the preceding claims, in which, for each interconnection element (INTR), pads of electrically insulating adhesive are deposited between the portions (P1, P2, P3, PN) of electrically conductive adhesive of the first film (F1).

7. Method (PROC) according to one of the preceding claims, in which, for each interconnection element (INTR), the first electrically conductive adhesive film (F1) extends over a first length (L1) of said interconnection element (INTR), between 30% and 50% of the total length (L) of each interconnection element (INTR).

8. Method (PROC) according to one of the preceding claims, in which each collection electrode (FGR) has a constant width.

9. Method (PROC) according to one of the preceding claims, comprising a step of arranging (PROC3) each interconnection element (INTR) so that the first film (F1) of electrically conductive adhesive is opposite the first photovoltaic cell (CELL1), the step of depositing (PROC1) the first film (F1) of electrically conductive adhesive being carried out simultaneously with this step of arranging (PROC3).

10. Method (PROC) according to one of the preceding claims, comprising a step of depositing (PROC2) a second film (F2) of electrically conductive adhesive on each interconnection element (INTR), the second film (F2) being distant from the first film (F1), and in which, for each interconnection element (INTR), the second film (F2) of electrically conductive adhesive extends over a second length (L2) of the interconnection element (INTR) and is discontinuous, the second film (F2) of electrically conductive adhesive comprising portions of electrically conductive adhesive distributed over the entire second length (L2) of the interconnection element (INTR).

11. Method (PROC) according to claim 10, wherein, each interconnection element (INTR) comprises a first side and a second side opposite to the first side, and wherein, for each interconnection element (INTR), the first film (F1) extends on the first side of said interconnection element (INTR) while the second film (F2) extends on the second side of said interconnection element (INTR).

12. Method (PROC) according to claim 10, wherein, each interconnection element (INTR) comprises a first side and a second side opposite to the first side, and wherein, for each interconnection element (INTR), the first and second films (F1, F2) extend on the first side of said interconnection element (INTR).

13. Method (PROC) according to claim 10 to 12, in which the deposition (PROC2) of the second film (F2) of electrically conductive adhesive is carried out simultaneously with the deposition of the first film (F1) of electrically conductive adhesive.

14. Method (PROC) according to one of claims 10 to 13, comprising the following additional step: - depositing (PROC6) each interconnection element (INTR) on a second photovoltaic cell (CELL2), the second film (F2) of electrically conductive adhesive of each interconnection element (INTR) being arranged in contact with the second photovoltaic cell (CELL2).

15. Device (DISP) for bonding at least one interconnection element (INTR) to a first photovoltaic cell (CELL1) comprising: - at least one applicator (APP1, APP2) of electrically conductive adhesive; - means of gripping (PREH) and guiding (GD) the interconnection element (INTR); - means (CONV) for supporting the first photovoltaic cell (CELL1); and - means (CTRL) configured to execute the steps of the method (PROC) of gluing according to one of the preceding claims.

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