Embossed flexible interconnection structure for shingle-type solar technology
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
- Filing Date
- 2024-08-29
- Publication Date
- 2026-07-08
Smart Images
Figure EP2024074220_06032025_PF_FP_ABST
Abstract
Description
[0001] EMBOSSED FLEXIBLE INTERCONNECTION STRUCTURE FOR SHINGLE-TYPE SOLAR TECHNOLOGY
[0002] DESCRIPTION
[0003] TECHNICAL FIELD
[0004] The present application relates to the field of electrical interconnection structures for sets of photovoltaic cells, also called solar cells. It provides for the production of an improved interconnection structure as well as that of a set, or a chain, of solar cells provided with such an interconnection structure.
[0005] A conventional solar or photovoltaic module is typically formed from one or more sets of several juxtaposed cells distributed in chains (commonly called "strings" in English terminology). A chain (or "string") of cells comprises a succession of several cells electrically connected to each other and generally aligned in a given first direction. The connection between cells of the same chain can be achieved by means of conductive strips or wires which extend in the first direction and successively come into contact with at least one upper or lower face of each cell.
[0006] To improve the surface power of a photovoltaic module, it is known to achieve a densification of the distribution of cells by reducing the inter-cell spaces within the same chain of cells, or even by making the cells of the same chain overlap each other.
[0007] Document US2021202784 describes, for example, a particular way of assembling the cells of a chain of cells in which the cells overlap each other in a "shingle" type arrangement, commonly called a "shingle" or, except for the end cells of a chain, each cell overlaps a previous neighboring cell and is overlapped by a next neighboring cell in the succession of cells forming the chain. A structure of the type called "paving" uses a similar arrangement but with conductive ribbons or wires to make the connection between the cells. Another type of arrangement provides, except for the end cells of a chain, that each cell is either overlapped by its previous and next neighboring cells, or overlaps its previous and next neighboring cells in the succession of cells.Such an arrangement and assembly of cells has the advantage of not having a dead zone between cells. However, such an arrangement most of the time results in a rigid mechanical structure limiting deformation in the plane of the cells. This poses a problem when the cells are subjected to mechanical or thermomechanical constraints.
[0008] Document WO 2022 / 023659 from the applicant provides an improved interconnection and assembly structure for overlapping solar cells. The proposed interconnection structure is provided with a metal strip located between the two cells to be connected with electrical connection pads alternately on the front and rear faces of the metal strip, the pads located on the front face being offset relative to the pads arranged on the rear face. Such an arrangement makes it possible to achieve mechanical decoupling and to better relax mechanical or thermomechanical stresses.
[0009] The problem arises of finding a new interconnection structure for a set of solar cells with adjacent overlapping solar cells, and which is improved in particular in terms of mechanical decoupling between adjacent cells.
[0010] STATEMENT OF THE INVENTION
[0011] One embodiment of the present invention relates to an interconnect structure comprising:
[0012] - an oblong conductive element,
[0013] - a first insulating strip which extends against said oblong conductive element and is provided with one or more first holes successively distributed along the first insulating strip, - a second insulating strip which extends against said oblong conductor is provided with one or more second holes successively distributed along the second insulating strip, the oblong conductive element being provided with one or more portions arranged between the first insulating strip and the second insulating strip, the oblong conductive element further comprising a succession of conductive folds, one or more first folds among said conductive folds passing respectively through one or more first holes of the first insulating strip and one or more second conductive folds among said conductive folds passing through one or more second holes of the second insulating strip.
[0014] The first conductive folds may be provided to be contacted with a first solar cell of a set of solar cells while the second conductive folds may be provided to be contacted with a second solar cell of said set of solar cells or with a conductive track.
[0015] Such an interconnection structure is particularly suitable for the interconnection of adjacent solar cells of a partially overlapping cell chain.
[0016] The conductive folds of such an interconnection structure induce a spring effect which gives an assembly of cells between which it is interposed increased mechanical flexibility in a plane orthogonal to the cells and makes the assembly of cells less sensitive to possible thermomechanical constraints.
[0017] The interconnection structure can optionally be adapted to a so-called “dry” contact, i.e. without using intermediate solder or glue to bond it to a solar cell.
[0018] Advantageously, the oblong conductive element is provided, on either side of at least one of said portions: with a first conductive fold extending through a first hole and at least one second conductive fold extending through a second hole.
[0019] Advantageously, the first ply(ies) extend(s) beyond an outer face of the first insulating strip. Advantageously, the second ply(ies) extend(s) beyond an outer face of the second insulating strip.
[0020] According to one possible implementation of the structure, the first hole and the first fold passing through the first hole are arranged opposite an area of the second insulating strip while the second hole and the second fold passing through the second hole are arranged opposite an area of the first insulating strip.
[0021] With such a configuration, a direct vertical connection between an area of the first cell located and another area of the second cell located directly above each other is avoided.
[0022] This gives mechanical flexibility to the assembly, between the upper and lower contact recovery.
[0023] The presence of a permanent restoring force on the electrical contact point, in other words a spring effect at the interconnection level, ensures permanent plating of the conductive element on the contact pad, and thus avoids the appearance of a possible electric arc.
[0024] According to one possibility, the first conductive folds may have a periodic distribution along said oblong conductive element.
[0025] Similarly, the second conductive folds may have a periodic distribution along said oblong conductive element. Such a distribution of the folds makes it possible to obtain a balanced distribution of the stresses when the interconnection structure is interposed or arranged between two elements, in particular between two solar cells.
[0026] According to one possible implementation, the portions of the oblong conductive element arranged between the first insulating strip and the second insulating strip extend parallel to a first axis parallel to which the insulating strips also extend.
[0027] Such so-called flat and possibly flattened portions contribute to improved vertical mechanical support of the conductive element. Areas of the insulating strips located on each face of these flat portions and forming double insulation on these flat portions may also contribute to the vertical mechanical support of the structure. According to an advantageous embodiment, the first hole(s) and the second hole(s) may have a rounded outline or be formed from curved portions. Such a hole configuration makes it possible to limit the risks of tearing of the insulating strips.
[0028] According to another aspect, the present invention provides an assembly of solar cells typically arranged in at least one cell chain and comprising:
[0029] - at least one first solar cell,
[0030] - at least one second solar cell,
[0031] - at least one interconnection structure as defined previously and the first conductive folds of which are in contact with a region of the first cell while the second conductive folds are in contact with an area of the second cell opposite said region of said first cell.
[0032] This set of cells can have a paving or tiling arrangement (“shingle”) and include a succession of partially overlapping cells.
[0033] According to another aspect, the present invention provides a solar cell assembly comprising:
[0034] - a first solar cell,
[0035] - a second solar cell,
[0036] - an interconnection structure as defined above, the first folds of which are in contact with a region of the first cell of said assembly and the second folds of which are in contact with a conductive track, typically an end conductive track located at one end of a chain of cells.
[0037] According to one possible arrangement, the first conductive fold(s) may be arranged in the same first plane, in particular a plane orthogonal to the first insulating strip and to the second insulating strip, while the second conductive fold(s) extend in a second plane making a non-zero angle with the first plane and in particular 90° with the first plane. Such a configuration with first folds having a different orientation from the second folds is particularly suitable for an interconnection of elements which are not arranged one above the other, but are juxtaposed, for example to interconnect a face of a solar cell with a conductive track juxtaposed or arranged next to this cell.
[0038] According to one implementation possibility, the first insulating strip may be attached to an insulating sheet transparent to solar radiation and covering one face of the first solar cell. Advantageously, the second insulating strip may also be attached to an insulating sheet transparent to solar radiation and covering one face of the second solar cell.
[0039] This insulating sheet can be advantageously detachable from the insulating strip to which it is connected. To facilitate this detachment, a cutting line typically in the form of a succession of days between the insulating strip and the insulating sheet can be advantageously provided.
[0040] According to another aspect, the present application relates to a solar cell assembly in which the first cell and the second cell each have a lower edge and an upper edge and two opposite side edges located between the lower edge and the upper edge, the side edges being preferably arranged parallel to said first axis, the interconnection structure being arranged along a side edge of the first cell and a side edge of the second cell, said first and second cells being offset from each other such that an upper edge of the first cell is misaligned with respect to an upper edge of the second cell and a lower edge of the first cell is misaligned with respect to a lower edge of the second cell.
[0041] An interconnection structure as defined above is thus particularly suitable for chains of cells which are not straight.
[0042] According to a particular embodiment in which the first cell and the second cell are arranged such that a side edge of the first cell partially overlaps a side edge of the second cell and the offset of the first solar cell relative to the second solar cell is such that a given region of said side edge of said first cell protrudes beyond an upper or lower edge of said second cell, the interconnection structure may further extend on said first cell along said given region. The interconnection structure on the first cell may thus be extended beyond the overlapping area between the first cell and the second cell in order to improve charge collection on the first cell. A corresponding arrangement may be implemented along a side edge of the second cell protruding relative to an upper or lower edge of the first cell.
[0043] According to another aspect, the present invention relates to a method of manufacturing an interconnection structure as defined above.
[0044] In particular, one embodiment of the method comprises steps of:
[0045] - providing an oblong conductive element which extends mainly along a first axis and forming a succession of folds relative to said first axis along this oblong conductive element,
[0046] - assembling the oblong conductive element with a first perforated insulating strip and a second perforated insulating strip, the assembly being carried out so as to pass one or more first plies of said succession through one or more first holes of the first insulating strip, and one or more second plies of said succession passing respectively through one or more second holes of the second insulating strip.
[0047] Advantageously, the formation of the folds is carried out by embossing.
[0048] A particular embodiment of the embossing comprises the passage of the conductive element between two rotating toothed wheels.
[0049] According to one possible implementation, the method may comprise at least one step of perforating the first insulating strip and / or the second insulating zone.
[0050] The production of holes in this or these insulating strips can advantageously be carried out using a laser.
[0051] According to one possible implementation, the assembly of the first insulating strip and the second insulating strip on the oblong conductive element may comprise a heating step to secure the first insulating strip and the second insulating strip together. According to another aspect, the present invention relates to a method for manufacturing a photovoltaic device comprising a set as defined above of solar cells. Such a manufacturing method may comprise steps consisting of:
[0052] - place the first insulating strip against areas of the first solar cell,
[0053] - heating the insulating strips so as to make the first insulating strip adhere to said areas of the first solar cell.
[0054] BRIEF DESCRIPTION OF THE DRAWINGS
[0055] The present invention will be better understood on the basis of the following description and the attached drawings in which:
[0056] Figure 1 illustrates an example of an interconnection structure with successive conductive folds suitable for interconnecting elements, in particular adjacent overlapping solar cells in a solar cell string.
[0057] Figures 2A, 2B, 2C, 2D and 2E illustrate different examples of conductive fold profiles in an interconnection structure as implemented according to the invention.
[0058] Figure 3 illustrates an example of a method for assembling constituent elements of an interconnection structure for solar cells.
[0059] Figure 4 illustrates a particular shape of hole outline made in an insulating strip belonging to an interconnection structure implemented according to an embodiment of the present invention.
[0060] Figures 5A and 5B illustrate an arrangement of laterally overlapping solar cells connected to each other via a conductive fold interconnect structure and as implemented in accordance with one embodiment of the present invention.
[0061] Figure 6 illustrates an alternative embodiment in which the insulating strips of the interconnection structure are attached to insulating and transparent sheets intended to cover the solar cells. Figure 7 illustrates an arrangement with several cell strings, a first cell string being provided with at least one cell interconnection structure connected to another cell interconnection structure of a second cell string.
[0062] Figure 8 illustrates an arrangement in which the conductive fold interconnect structure allows a solar cell to be connected to a metal track located in particular at one end of a cell string.
[0063] Figures 9 and 10 illustrate an arrangement in which the interconnection structure is provided with conductive folds extending parallel to a first plane, in particular vertical, and other conductive folds extending parallel to a second plane, in particular horizontal.
[0064] Figures 11 and 12 illustrate a folding step for obtaining conductive folds at 90° to other conductive folds in an interconnection structure according to an embodiment of the present invention.
[0065] Figure 13 illustrates a particular embodiment of an interconnection structure.
[0066] Figure 14 illustrates an example of an arrangement of interconnections according to the invention in a chain of solar cells.
[0067] Figure 15 illustrates an alternative arrangement of an interconnection structure according to the invention in a string of solar cells.
[0068] Figure 16 illustrates a particular arrangement of a string of solar cells with misaligned side edges.
[0069] Figure 17 illustrates a particular arrangement of interconnection structures according to the invention integrated into a string of solar cells with misaligned side edges.
[0070] Figure 18 illustrates an example of a particular configuration and sizing of an interconnect structure as implemented according to an embodiment of the present invention.
[0071] Identical, similar or equivalent parts of different figures bear the same numerical references so as to facilitate the transition from one figure to another.
[0072] The various parts shown in the figures are not necessarily shown on a uniform scale, in order to make the figures more readable. DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
[0073] We now refer to Figure 1 giving a side view of an example of an interconnection structure 5 for a set of solar cells (not shown in this figure). The structure 5 may in particular be intended to be interposed between neighboring or adjacent solar cells of a string of solar cells and to make it possible to make an electrical connection between these neighboring or adjacent solar cells.
[0074] This interconnection structure 5 is formed of at least one oblong conductive element 11 which may be in the form of at least one conductive wire or at least one conductive strip, or a conductive ribbon, which may advantageously be of flat and elongated shape and which extends mainly along a first axis XI.
[0075] The oblong conductive element 11 is typically based on one or more metallic material(s) such as for example copper, silver, aluminum, or an iron-based material, possibly steel. Advantageously, the oblong conductive element 11 may be formed from several metallic materials distributed in a core-shell arrangement. The conductive element 11 may optionally be coated with a thin metallic layer for protection against oxidation and be formed for example from tinned copper.
[0076] The oblong conductive element 11 here comprises portions 12c called “planes” which extend substantially parallel or parallel to the first axis XI and a succession of conductive sections which make detours called “conductive folds 12a, 12b” relative to the first axis XI. Each conductive fold 12a, 12b comprises an area intended to come into contact with a solar cell or a conductive track.
[0077] The conductive folds 12a, 12b are formed here from portions of thickness substantially equal to that of said flat portions 12c.
[0078] The structure comprises in particular one or more first conductive folds 12a also called “upper” folds on a first face 7A or on a first side of the interconnection structure 5 and one or more second first conductive folds 12b also called “lower” folds on a second face 7B opposite the first face 7A or on a second side opposite the first side of the interconnection structure 5.
[0079] The folds 12a, 12b are, in this particular embodiment, in the form of undulations or curved portions on either side of the first axis XI and are intended, for the first folds 12a to be connected or in contact with conductive zones of a first solar cell and for the second folds 12b opposite the first folds 12b, to be connected or in contact with conductive zones of a second solar cell partially facing the first solar cell so that an electrical contact is made. Direct contact of the folds 12a, 12b on the solar cells, that is to say without soldering or without intermediate glue, can possibly be implemented.
[0080] The conductive folds 12a, 12b make it possible to give flexibility to the structure 5 in a direction orthogonal to the first axis XI and to the main plane of solar cells between which the interconnection structure is to be interposed.
[0081] The alternation of “upper” 12a and “lower” 12b folds enhances this spring effect.
[0082] To allow a balanced distribution of stresses and contact resistances, a periodic distribution of the conductive folds 12a, 12b on either side of the interconnection structure 5 is preferred.
[0083] Here, a direct connection along a vertical path of the cells between them by the interconnection structure 5 is preferably avoided, by providing for coating certain zones of the oblong conductive element 11 with insulating material.
[0084] Thus, in the particular embodiment of Figure 1, on one side or at the first face 7A, the oblong conductive element 11 is coated on certain portions, in particular on its flat portions 12c, with a first insulating strip 20 extending parallel to the first axis XI. The first insulating strip 20 is provided with one or more holes 21 successively distributed along the first insulating strip 20, through each of which passes a first conductive fold 12a which protrudes at the first face 7A of the structure 5. On the other side or at the second face 7B, the oblong conductive element 11 is coated on certain portions, in particular on its flat portions 12c, with a second insulating strip 30 extending parallel to the first direction XI. The conductive element 11 is thus interposed or sandwiched at its flat portions 12c between the first insulating strip 20 and the second insulating strip 30.Such areas facilitate holding in position solar cells intended to be arranged respectively on and under the interconnection structure 5.
[0085] The second insulating strip 30 is also provided with one or more holes 31 successively distributed along the second insulating strip 30 and through each of which passes a second conductive fold 12b or upper conductive fold 12b which protrudes at the level of the second face 7B of the structure 5.
[0086] Advantageously, as in the particular case of FIG. 1, the tops 13 of the conductive folds 12a, 12b protrude from the holes 21, 31 and extend beyond the external faces 23, 33 of the insulating strips 20, 30.
[0087] The insulating strips 20, 30 are made of an insulating material having transparency in the spectrum dedicated to silicon solar cells, in other words for a wavelength typically between 400 nm and 1200 nm. This insulating material may be polymer-based, in particular a polyimide such as for example Kapton™ or PET (poly(ethylene terephthalate), or a PE / PET multi-layer. The first insulating strip 20 and the second insulating strip 30 may advantageously be coated or provided with at least one adhesive face and in particular an external adhesive face 23, 33 to facilitate assembly with the solar cells. The adhesive is provided to allow mechanical retention and handling.
[0088] The conductive folds 12a, 12b are, in this particular embodiment, distributed along the first axis XI, alternately on the first face 10A and on the second face 10B, with, preferably, an offset provided from one conductive fold 12a to the other 12b along this first axis XI. The entire first conductive fold(s) 12a formed on the first face 7A is thus here offset from the entire conductive fold(s) 12b located on the second face 7B. In the succession of conductive folds 12a, 12b, along the axis XI each first conductive fold 12a is offset from a next opposite conductive fold 12b located on an opposite face. The opposite folds 12a and 12b are here separated two by two by a flat portion 12c of the conductive element 11.
[0089] An alternating positioning of the holes 21, 31 along the first axis is also implemented here. Thus, the holes 21 of the first insulating strip 20 are here also advantageously offset from all of the holes 31 of the second insulating strip 30 located on the second face 7B, so that a hole 21 of the first insulating strip 20 is arranged opposite a non-perforated portion of the second insulating strip 30. Similarly, a hole 31 of the second insulating strip 30 is arranged opposite a non-perforated portion of the first insulating strip 20.
[0090] Thus, a conductive fold 12a located on the first face 7A of the structure 5 and intended to be brought into contact with a first cell is arranged opposite an insulating portion 30a of the second insulating strip 30. Similarly, a conductive fold 12b located on the second face 7B of the structure 5 and intended to be brought into contact with a second cell is arranged opposite at least one insulating portion 20a of the first insulating strip 20. This arrangement implies that the electrical connection between the two cells is not established along a vertical conduction path (axis parallel to the vector z of the orthogonal reference frame [0; x; y; z]), but along a path changing direction several times.
[0091] As illustrated in Figures 2A, 2B, 2C, 2D, 2E, different shapes can be provided for the conductive folds 12a, 12b of an interconnection structure of the type described previously.
[0092] Thus, in the embodiment example of Figure 2A, the conductive fold is provided with a curved profile 201. A fold shape formed from several sections making one or more angles can also be provided. Thus in Figure 2B, a fold of trapezoidal shape with a section 202a making a non-zero angle with the first axis XI, followed by a section 202b substantially parallel to the first axis XI itself followed by a section 202c making a non-zero angle with the first axis XI. Such a fold profile makes it possible to make a surface contact rather than a point contact on a solar cell or a conductive track. In the particular embodiment example of Figure 2C, the profile of the fold is of triangular or peak shape and comprises a section 204a making a non-zero angle with the first axis XI, followed by a section 204b making an angle with the section 204a.As in the particular embodiment of figures 2D and 2E, conductive folds whose respective profiles are formed from a succession of undulations 206 can also be implemented.
[0093] Such conductive folds and fold profiles can be obtained for example by stamping or embossing areas of a conductive wire or tape.
[0094] Certain geometric parameters or quantities can be adapted to improve the properties of the interconnection structure.
[0095] Thus, in the particular embodiment illustrated in Figure 18, the thickness ei of the conductive strip 11 is advantageously provided to be less than the thickness e2 of the insulating strips 20, 30. This makes it possible to have a more pronounced elastic return on the pad for contact recovery. The thickness ei can be between 10 and 200 pm, for example of the order of 50 pm.
[0096] In the particular embodiment illustrated in Figure 18, conductive folds 12a, 12b are provided distributed according to a periodic arrangement with a pitch A of distribution of the conductive elements 12b and a maximum diameter or dimension D of the holes 21, 31. Preferably, D < A / 2 is chosen so as to guarantee an overlapping zone of the two insulating strips 20, 30 and thus ensure better vertical mechanical support of the oblong conductive element 11 when it is brought into contact between two cells to be interconnected.
[0097] The distribution pitch A of the folds and the number of conductive folds planned depend in particular on the format of the cells. For example, in the particular case of M12 format solar cells, we can consider a number of conductive folds between 10 and 20 with a distribution pitch A for example between 10 and 20 mm.
[0098] In the particular embodiment illustrated, the conductive folds 12a, 12b protrude from the holes 21, 31 by a non-zero protrusion length d measured relative to the external surface 23, 33 of the insulating strips 20, 30, which makes it possible to improve the contact and the connection with the cells. The spring effect on the cell contacts which will guarantee the electrical connection may depend in particular on this protrusion length d.
[0099] A minimum overhang length dmin is preferably provided in order to maximize the spring effect of the structure.
[0100] An example of a method for calculating this minimum overhang length dmin will be given for a conductive element 11 in the form of a flat copper strip 1 mm wide W (dimension measured orthogonally to the plane of the figure) and 50 pm thick ei.
[0101] The calculation implemented here amounts to determining the deflection on a fixed beam to predict from which the material reaches its elastic limit.
[0102] In this case, we consider a simple beam of rectangular section with a thickness and width corresponding to that of the ribbon, for example 50 pm and 1 mm respectively. The system for the example is considered with a "recessed - free" beam 5 mm long.
[0103] We calculate I, the quadratic moment of the section: I = W(ei) 3 / 12, or 1=1.04*10-5 mm 4
[0104] Let P be the weight exerted on the conductive element 11 ribbon to be determined to reach the elastic limit (sigma bend max) of 50Mpa for copper.
[0105] In this case: abend, max= (Mxc) / I with c the perpendicular distance between the neutral tax and the most distant point of the section, M = LxP, L the length of the oblong conductive element considered.
[0106] With M = LP, this is the maximum distance from the neutral axis, i.e. 25pm, and I the quadratic moment of the section, calculated previously.
[0107] We extract P:
[0108] P= 4.16x10-3 N for copper
[0109] For a conductive element 11 made of steel of the same dimensions we have P = 0.025 N.
[0110] For example, we consider the mass m of a silicon solar cell with a density of 2.33 and an M12 format; we then have m of the order of 13g. From the corresponding weight, we deduce the value of the deflection f that this force P will generate at the end of a beam of length L and Young's modulus E: with f= (PL 3 ) / 3EI.
[0111] This gives f = 180 pm for a copper beam and f = 455 pm for a steel beam.
[0112] To fully benefit from the spring effect in the case described in the example, we take d >= dmin with dmin of the order of 180 pm for a copper / silver conductive element, and of the order of 455 pm for a steel conductive element.
[0113] A minimum overhang length dmax of, for example, around 10 mm can be provided.
[0114] An example of a method of manufacturing an interconnect structure of the type described above is illustrated in Figure 3.
[0115] First of all, an oblong conductive element 11 is provided in the form of a conductive wire or strip.
[0116] In this example, the conductive element 11 is moved by means of a conveying structure 302 which may be formed of rotating rollers and between which the conductive element 11 may be inserted to be brought to an embossing device 310. The conveying structure 302 may be provided with elements of the roll-to-roll type.
[0117] In the particular embodiment, the embossing device 310 is provided with two rotating toothed wheels 312, 313 between which the oblong conductive element 11 is inserted and moved. The teeth 316 of the rotating wheels 312, 313 make it possible to stamp the conductive element 11 in order to form the conductive folds 12a, 12b. These teeth 316, the shape of which determines that of the folds, are preferably regularly distributed so as to form a periodic succession of conductive folds. The stamping of the conductive element 11 can be implemented so as to flatten and form or maintain certain flat areas. Such areas contribute to maintaining the interconnection structure in a stable position when it is interposed between two elements. A first insulating strip 20 and a second insulating strip 30 each provided with a succession of holes 21, 31 are then arranged on either side of the conductive element 11.The manufacture of the interconnection structure 5 may comprise a prior step of perforating these insulating strips 20, 30, for example using a laser, in order to produce the succession of holes 21, 31 along these strips 20, 30 and into which the conductive folds of the conductive element will be inserted.
[0118] The insulating strips 20, 30 are then brought against the oblong conductive element 11, so as to arrange the upper conductive folds 12a of the conductive element 11 respectively in the holes 21 of the first insulating strip 20 and the lower conductive folds 12b of the conductive element 11 in the holes 31 of the second insulating strip 30 and thus form the superposition of the first insulating strip, the oblong conductive element and the second perforated insulating strip.
[0119] To better fix the insulating strips 20, 30 on the conductive element 11, and possibly to secure the insulating strips 20, 30 together, a heating device 320, for example in the form of lateral heating elements 325A, 325B between which the assembly of the conductive element 11 and the strips 21, 31 is brought can be provided. For example, heating is carried out at a temperature of for example between 60°C and 150°C, typically between 90°C and 135°C when the insulating strips 20, 30 are made of PET.
[0120] Optionally, after having carried out this heat-sealing step, and in order to keep its elasticity, the interconnection structure 5 can be put into the form of a coil, for example by means of a winder 330.
[0121] In order to limit the risks of tearing of one or other of the insulating strips 20, 30 during their fixing on the conductive element 11 or even once the interconnection structure 5 has been produced, it is advantageous to provide the holes of the insulating strips 20, 30 with a rounded contour. Thus, in the particular embodiment illustrated in FIG. 4, a hole made in the first insulating strip 20 is provided with a contour 42 of rectangular appearance but comprising, instead of corner angles, portions 43 having a radius of curvature. If lo is considered as the width of the opening, the radius of curvature at the four corners is preferably less than lo / 2.
[0122] An interconnection structure 5 according to one or other of the examples described above is particularly suitable for an assembly and connection of solar cells in a tiling (“shingle”) or paving fashion as in FIG. 5A and in which solar cells Ci, C2 partially overlap in order in particular to achieve a compact assembly. By partially overlapping, it is meant here that one partially overflows above the other, the interconnection structure 5 being arranged between the cells Ci, C2 in a so-called “overlapping” zone between cells Ci, C2 where the cells are arranged facing each other.
[0123] An exploded perspective view of such an arrangement is given in Figure 5B. The solar cells Ci, C2 are here formed from a semiconductor substrate, which may be poly- or monocrystalline and in particular based on polycrystalline or monocrystalline silicon. Each of the cells Ci, C2 is provided with at least one face 2A called the “front face”, which receives light and is intended to be exposed to solar radiation, and a face 2B called the “rear face”, opposite the front face 2A. The rear face 2B may optionally also be intended to be exposed and convert the solar radiation into charge carriers. In this particular case, the solar cell is called “bifacial”.
[0124] At least one first solar cell Ci of this assembly is provided with contacts distributed on the rear face 2B, including one or more contacts (not visible) with respectively one or more N-type doped zones (in other words having a doping producing an excess of electrons) and one or more contacts (not shown in this figure) with respectively one or more P-type doped zones (in other words according to a doping consisting of producing a deficit of electrons), the N-type zone(s) associated with the P-type zone(s) forming at least one junction.
[0125] A peripheral zone 4 located on the rear face 2B of the first cell C1 is arranged opposite a peripheral zone 4' of the front face 2A of a second cell C2. In this embodiment, where the oblong conductive element 11 is advantageously in the form of a flat conductive ribbon 110 or a flat conductive strip, it is easier to keep the cells C1, C2 in position and prevents one from moving relative to the other.
[0126] Lateral portions 25, 35 of the insulating strips adhere to the upper and lower cells Ci, C2 to form encapsulation cavities around the conductive folds 12a, 12b in contact with the cells Cl, C2. The conductive folds 12a, 12b are preferably free to move in these cavities to allow the electrically conductive element 11 to exert a spring effect.
[0127] To produce an assembly of the interconnection structure 5 with the cells C1, C2, the second cell C2 can be placed in line on a cell string manufacturing machine commonly called a "stringer", in particular of the common type. The insulating strip 30, the oblong conductive element, the other insulating strip 20 are positioned, and the first cell Ci is placed on the assembly. Heating is then carried out, in particular, of the insulating strips. The insulating strips 20, 30 can, for example, come from rollers unrolling in a direction perpendicular to the direction of the cell string. The heat input can be considered as a temperature setting of the interface between the two materials, between 60°C and 150°C, typically between 90°C and 135°C at the insulating strips 20, 30 can make it possible to achieve partial adhesion of these insulating strips 20, 30 to the cells Ci, C2.Alternatively, the insulating strips 20, 30 are coated with an adhesive or have adhesive properties to attach the interconnection structure to the cells Ci, C2.
[0128] According to another embodiment possibility, with a pick and place device, the second cell C2 is positioned, the interconnection structure 50 already provided with its insulating strips 20, 30 on the latter, then the first cell Ci is positioned on the interconnection structure. The insulating strips are then optionally heated to make the interconnection structure adhere to the cells and / or to perfect the adhesion of these insulating strips to the cells. An alternative embodiment of the assembly previously described and illustrated in FIG. 6 provides insulating strips 20, 30 for the interconnection structure 5 attached respectively to an insulating sheet 65 transparent to solar radiation and to another insulating sheet 66 transparent to solar radiation.These insulating sheets 65, 66 respectively cover one face, here the rear face 2B of the first solar cell C1 and one face, here the front face 2A, of the second solar cell C2. The insulating sheets 65, 66 may be formed from a material similar and possibly identical to that of the insulating strips 20, 30.
[0129] Such insulating sheets 65, 66 make it possible to provide protection for the cells Ci, C2 from the external environment and in particular from air and humidity. They also make it possible to provide mechanical protection for the storage and handling of the cells Ci, C2 before or after they are assembled into a chain (commonly called a "string") of cells. They can also contribute to the implementation of thermal decoupling between the cells Ci, C2.
[0130] Advantageously, the insulating strip 21 (resp. 31) - insulating sheet 65 (resp. 66) assembly covers the face of the cell on which it is arranged and can protrude from the cell beyond this face.
[0131] In the particular embodiment illustrated, a discontinuous succession 67, 77 of days is provided between each sheet 65, 66 and its insulating strip 20, 30 to form a so-called cutting line in order to allow possible subsequent detachment between the insulating strip 20, 30 and the sheet 55, 65 to which this strip is connected.
[0132] An interconnection structure 5 as described above may be used in a device having several strings of solar cells connected to each other. In the particular embodiment given in FIG. 7, a first interconnection structure 5i is interposed between cells Ci, C2 of a first string STI of cells Ci, C2, overlapping in a shingle arrangement. This first interconnection structure 5i is connected to a second similar interconnection structure 52 which is arranged and aligned on the same axis XI.
[0133] The second interconnection structure 52 is provided to be interposed between cells Cn, C12 of a second chain ST2 of cells Ci, C2. To allow the passage of current in one direction only from the first chain STI to the second chain ST2 of cells and to prevent a current from flowing from the second chain ST2 to the first chain STI, an electronic component for example such as a diode 79 or a transistor can be provided between the conductive elements 11 of the two interconnection structures 5i, 52. A bypass diode between the chains typically has a protective role in the event of shading.
[0134] In the embodiment illustrated in Figure 7, the interconnection structures 5i, 52 can advantageously be overflowing towards a chain of adjacent cells and longer than the width WST of a chain.
[0135] In addition to the interconnection and assembly of two solar cells, an interconnection structure 5 according to one or other of the examples described previously can be adapted both in a solar module or a chain of solar cells to the connection of a solar cell and a conductive track.
[0136] Thus, in the embodiment of figure 8 (giving an exploded perspective view), the oblong conductive element 11 comprises conductive folds 12a intended to be placed in contact with a solar cell Ci, and conductive folds 12b intended to be placed in contact with a conductive track 89 here placed opposite a lower portion of the cell Ci.
[0137] In a case where it is desired to make a connection between the solar cell Ci and a conductive track 189 which is not located opposite the latter and is offset relative to the face 2B of the cell Ci to which this conductive track 189 is intended to be connected, an arrangement such as in FIGS. 9 and 10 may be provided. The conductive track 189 may be an end track of a string of cells and for example in the form of a metal strip.
[0138] The connection structure 5 comprises upper conductive folds 12a provided for making contact on one face, here the rear face 2B of the cell Ci and lower conductive folds 12'b which have the particularity of extending in a plane distinct from that of the upper conductive folds 12a. Thus, if certain folds 12a extend in a so-called "vertical" plane (plane orthogonal to the faces 2A, 2B of the cell and parallel to the plane [O; x; z] of the orthogonal reference [O; x; y; z] in Figures 9 and 10) other conductive folds 12'b extend in a "horizontal" plane (plane parallel to the faces 2A, 2B of the cell in Figures 9 and 10) orthogonally to the conductive folds 12a. Here, a double relaxation is implemented in two distinct directions or planes.
[0139] A method of manufacturing an interconnection structure 5 may thus comprise a folding step as shown schematically in FIG. 11 and in particular folding at 90° the conductive folds 12'b initially arranged in the same plane as the conductive folds 12a. In the particular embodiment illustrated in FIG. 12, the folding is carried out by bearing on the conductive track 189.
[0140] An interconnecting structure 5 of a type as previously described may be provided at each overlapping area between neighboring or adjacent cells of a chain of cells having a tiling or shingle arrangement.
[0141] Thus, in the particular embodiment illustrated in Figure 14, a chain of cells comprising k=6 cells Ci, C2, C3, C4, C5, C& parallel and distributed along an axis XI (parallel to the y axis of the orthogonal reference frame [O;x;y;z]) is provided with k-1 = 5 interconnection structures 5a, 5b, 5c, 5c, 5d, 5e of a type as described previously are each arranged at the level of an overlap zone between cells Ci and C2, or C2 and C3, or C4 and C5, or C5 and Ce.
[0142] In this figure, a right lateral edge of the cells Ci, C2, C3, C4, C5, is not represented at the level of said overlapping zones in order to make visible the interconnection structures 5a, 5b, 5c, 5c, 5d, 5e which are arranged under this right lateral edge.
[0143] Each structure 5a (respectively 5b, 5c, 5c, 5d, 5e) seen from above in transparency is here connected at the level of the overlapping zones and via its upper conductive folds to a set of pads 141 arranged on the rear face of a first cell Ci (respectively C2, C3, C4, C5). Each structure 5a, 5b, 5c, 5c, 5d, 5e is also connected at the level of the overlapping zones and via its lower conductive folds to a set of pads 143 arranged on the front face of a second cell C2 (respectively C3, C4, C5, Ce) neighboring the first cell and partially covered by the first cell.In this particular embodiment, at a first end of the chain of cells Ci, C2, C3, C4, C5, Ce, an interconnection structure 50a (of the type described previously) is advantageously provided on the cell Ci at the first end, provided with conductive folds connected to conductive pads 145 arranged on the cell Ci.
[0144] At a second end of the chain of cells Ci, C2, C3, C4, C5, C& located opposite the first end, there is provided here on the cell Ce of the second end of the chain, a conductive line 149 which extends over one face of the cell Ce, here its rear face, and which is connected to a conductive strip 159.
[0145] As a variant of the previous embodiment and as illustrated in FIG. 15, an interconnection structure 50b similar to that 50a located on the first cell Ci at the first end of the chain of cells can also be provided at the second end of the STR chain of cells Ci, C2, C3, C4, C5, Ce on the last cell Ce of the chain
[0146] An interconnection structure 5a, 5b, 5c, 5d, 5e of the type described above makes it possible, by virtue of the arrangement and repetition of its conductive folds, to adapt to different arrangements of cell chains and in particular to a chain configuration where, unlike the previous embodiment, the upper and lower edges of the cells are not all aligned with each other. An arrangement of solar cells of the same chain whose edges are offset and not aligned with each other in order to be able to fit a shape, for example a curve against which the chain is arranged, can be produced.
[0147] Thus, in the example illustrated in Figure 16, a chain STR' of cells Ci, C2, C3, C4, C5, Ce overlapping two by two is arranged such that in a direction parallel to the main axis of the chain (direction parallel to the y axis), the cells Ci, C2, C3, C4, C5, Ce are provided with respective lower edges I6I1, 16I2, 16I3, 16I4, 16I5, 161e and upper edges 162i, 1622, 162s, 1624, 162s, 162e which are parallel to each other but are not aligned with each other. Such an offset between the respective upper and lower edges of the successive cells Ci, C2, C3, C4, C5, C& can be implemented in order to adapt to a particular surface shape of a part or of a zone Z on which or against which one wishes to place the STR' chain of cells.
[0148] An alternative arrangement of the previously described embodiment provides an interconnection structure 5a which extends over a portion 173 of a first cell Ci along a given region of a lateral edge 164i of the first cell Ci and which protrudes from a lower edge 1622 of the second cell C2. The interconnection structure further also extends over the second cell C2 along a given area of a lateral edge 163i of the second cell C2 which protrudes from an upper edge I6I1 of the first cell Ci.
[0149] Each interconnection structure 5a, 5b, 5c, 5d, 5e can thus be arranged over a distance greater than the length L (direction parallel to the x axis of the orthogonal reference frame [O; x; y; z]) and comprise at least one portion 171 which extends on the upper face of a cell C2 beyond the overlapping or overlapping zone between these two adjacent cells Ci and C2 and / or at least one portion 173 which extends on the lower face of another cell Ci beyond the overlapping or overlapping zone between these same two adjacent cells Ci and C2.
[0150] Compared to an interconnection which would be located only in the overlapping zone, such an arrangement variant where it is planned to extend the arrangement of the interconnecting structures 5a, 5b, 5c, 5d, 5e beyond the overlapping or covering zones between adjacent cells C1-C2, C2-C3, C3-C4, C4-C5, C5-Ce makes it possible to improve current collection to the extent that the current tapping zone is extended.
[0151] Different application areas are possible for a photovoltaic device equipped with one or more interconnection structures as described above.
[0152] Such a device can be applied in particular to space, or integrated into an X-IPV type system, providing for the integration of solar modules on any type of surface, for example that of a building, or into a V-IPV type system providing for the integration of solar modules in rolling and / or flying objects or machines. Applications for which the layout of solar cells on a particular surface is delicate or susceptible to high thermal amplitudes are particularly targeted.
Claims
CLAIMS 1. Interconnection structure (5, 5a, 5b, 5c, 5d, 5e) for a solar cell assembly comprising: - an oblong conductive element (11), the oblong conductive element (11) being provided with one or more portions (12c) arranged between a first insulating strip (20) and a second insulating strip (30), such that the first insulating strip (20), said portions and the second insulating strip (30) are superimposed, - the first insulating strip (20) extending along said oblong conductive element and against said portions of said oblong conductive element, the first insulating strip (20) comprising one or more first holes (21) successively distributed along the first insulating strip, - the second insulating strip (30) extending along said oblong conductive element and against said portions of said oblong conductive element, the second insulating strip (30) comprising one or more second holes (31) successively distributed along the second insulating strip, the oblong conductive element (11) further comprising a succession of conductive folds (12a, 12b), including one or more first conductive folds (12a) passing respectively through said one or more first holes (21) of the first insulating strip (20) to allow a connection of the first conductive folds (12a) with a first solar cell of said set of solar cells and one or more second conductive folds passing respectively through said one or more second holes (31) of the second insulating strip (30) to allow a connection of the conductive folds with a conductive track or with a second solar cell of said set of solar cells.
2. Interconnection structure according to claim 1, the oblong conductive element (11) being provided, on either side of at least one of said portions, with a first conductive fold (12a) extending through a first hole (21) and at least one second conductive fold (12b) extending through a second hole (31), the first The hole (21) and the first fold (12a) passing through the first hole (21) being arranged opposite an area (30a) of the second insulating strip (30), the second hole (31) and the second conductive fold (12b) passing through the second hole (31) being arranged opposite an area (20a) of the first insulating strip (20).
3. Interconnection structure according to one of the preceding claims, the first conductive folds (12a) and / or the second conductive folds (12b) having a periodic distribution along said oblong conductive element (11).
4. Interconnection structure according to one of the preceding claims, in which the first insulating strip (20), the second insulating strip (30) and said portions (12c) arranged between the first insulating strip (20) and the second insulating strip (30) extend parallel to the same first axis (XI).
5. Structure according to one of the preceding claims, in which the holes (21, 31) have a rounded outline or formed from curved portions (43).
6. Set of solar cells comprising: -a first solar cell (Cl), -a second solar cell (C2), -an interconnection structure (5, 5a, 5b, 5c, 5d, 5e) according to one of claims 1 to 6, arranged between the first solar cell and the second solar cell, the first conductive folds (12a) being in contact with a region of the first cell, the second conductive folds (12b) being in contact with an area of the second cell opposite said region of said first cell.
7. Set of solar cells comprising: - a first solar cell (Cl), - an interconnection structure according to one of claims 1 to 6, the first folds being in contact with a region of the first cell of said assembly, the second folds being in contact with a conductive track (89, 189).
8. Solar cell assembly according to claim 7, the first conductive fold(s) (12a) being arranged in the same first plane, in particular a plane orthogonal to the first insulating strip (20) and to the second insulating strip (30), the second conductive fold(s) (12'b) extending in a second plane making a non-zero angle, in particular 90° with said first plane.
9. Solar cell assembly according to one of claims 6 to 8, in which the first insulating strip (20) is attached to an insulating sheet (65) transparent to solar radiation and covering one face of the first solar cell (Cl).
10. Solar cell assembly according to one of claims 6 to 9, wherein said first cell and said second cell each comprise a lower edge and an upper edge as well as two opposite lateral edges located between the lower edge and the upper edge, the connection structure is arranged along a lateral edge of the first cell and a lateral edge of the second cell, said first and second cells being offset from each other so that the upper edge (1621) of the first cell (C1) is misaligned with respect to the upper edge (1622) of the second cell (C2) and the lower edge (1611) of the first cell (C1) is misaligned with respect to the lower edge (1612) of the second cell (C2).
11. A solar cell assembly according to claim 10, wherein the first cell (C1) and the second cell (C2) are arranged such that a side edge of the first cell (C2) partially overlaps a side edge of the second cell (C2) and the offset of the first solar cell relative to the second cell solar is such that a given region of said lateral edge of said first cell (Cl) protrudes from an upper or lower edge of said second cell (C2), the interconnection structure further extending over said first cell along said given region.
12. Method of manufacturing a connection structure according to claims 1 to 6, comprising the following steps: - providing an oblong conductive element (11) which extends mainly along a first axis (XI) then forming a succession of folds relative to said first axis along this oblong conductive element (11), - assembling the conductive element (11) with a first perforated insulating strip (20) and a second perforated insulating strip (30), the assembly being carried out so as to pass one or more first plies of said succession through one or more first holes of the first insulating strip, and one or more second plies of said succession passing respectively through one or more second holes of the second insulating strip.
13. Manufacturing method according to claim 12, in which the formation of the folds is carried out by embossing, the embossing being in particular implemented by passing the conductive element between two rotating toothed wheels (312, 313).
14. Manufacturing method according to one of claims 12 or 13, further comprising at least one perforation step, in particular using a laser, so as to form said holes in the first insulating strip and / or in said second insulating strip.
15. Method according to one of claims 12 to 14, in which the assembly of the first insulating strip (20) of the oblong conductive element (11) and of the second insulating strip (30) comprises a heating step for securing the first insulating strip (20) and the second insulating strip (30) together.
16. A method of manufacturing a solar cell assembly according to one of claims 6 to 11, wherein the first insulating strip is arranged against areas of the first solar cell, the method comprising a step of heating the insulating strips (20, 30) so as to cause the first insulating strip to adhere to said areas of the first solar cell.