WO2020094980A1

WO2020094980A1 - Photovoltaic device

Info

Publication number: WO2020094980A1
Application number: PCT/FR2019/052631
Authority: WO
Inventors: Alain Straboni
Original assignee: S'tile
Priority date: 2018-11-07
Filing date: 2019-11-06
Publication date: 2020-05-14
Also published as: FR3088140B1; CN216450658U; FR3088140A1; EP3878019A1

Abstract

The invention relates to a photovoltaic device (300) which comprises a juxtaposition of elementary cells (302) that are connected in series by open-work conductive layers (304).

Description

DESCRIPTION

Photovoltaic device

The present patent application claims priority from the French patent application FR18 / 71388 which will be considered as an integral part of the present description.

Technical area

The present description relates to the field of photovoltaic devices, and more particularly relates to photovoltaic devices comprising several interconnected photovoltaic cells.

Prior art

It has already been proposed, for example in French patent application No. 16/54518 filed by the applicant on May 20, 2016, photovoltaic devices comprising several elementary photovoltaic cells interconnected.

It would however be desirable to at least partially improve certain aspects of known photovoltaic devices.

Summary of 1 ¹ invention

[0004] Thus, one embodiment provides a photovoltaic device comprising a juxtaposition of elementary cells connected in series by adjoined conducting plies.

According to one embodiment, each conductive sheet has a form of grid.

According to one embodiment, each conductive sheet consists of a plurality of braided conductive son forming a mesh, or a one-piece mesh.

According to one embodiment, each conductive sheet is in contact on the one hand, by its rear face, with a first collecting structure on the front face of a first cell and on the other hand, by its front face, with a second collecting structure on the rear face of a second cell close to the first cell.

According to one embodiment, the conductive layers are not fixed to the first and second collector structures.

According to one embodiment, each conductive sheet is fixed to the first collecting structure by its edge farthest from the second cell, and to the second collecting structure by its edge farthest from the first cell.

According to one embodiment, the first collecting structure is a discontinuous conductive pattern formed in a metal layer disposed on and in contact with the front face of a semiconductor plate of the first cell.

According to one embodiment, the neighboring cells are arranged side by side in the same plane.

According to one embodiment, the neighboring cells overlap.

According to one embodiment, each sheet has a width substantially equal to the width of the elementary cells.

According to one embodiment, each sheet has a length between one quarter and three quarters of the length of the elementary cells.

According to one embodiment, the elementary cells and the conductive layers are arranged between a transparent front face protection plate and a rear face protection plate. According to one embodiment, the device is in the form of a curved or corrugated plate.

Another embodiment provides an assembly comprising a plurality of photovoltaic devices as defined above connected in parallel between first and second terminals of the assembly, in which each conductive sheet connecting to one another two neighboring cells of the same photovoltaic device is common to all the photovoltaic devices of

1 assembly.

Brief description of the drawings

These characteristics and their advantages, as well as others, will be described in detail in the following description of particular embodiments made without implied limitation in relation to the attached figures among which:

Figure 1 schematically shows an example of an assembly of photovoltaic cells;

2 illustrates an embodiment of a collector structure and connection pads of a photovoltaic cell of the assembly of Figure 1;

Figure 3 schematically shows an example of an assembly of photovoltaic cells according to a first embodiment;

Figure 4 shows schematically an alternative embodiment of an assembly of photovoltaic cells according to the first embodiment;

Figure 5 shows schematically another alternative embodiment of an assembly of photovoltaic cells according to the first embodiment; Figure 6 shows schematically another example of an assembly of photovoltaic cells according to the first embodiment;

Figure 7 shows schematically an alternative embodiment of a conductive connection element of an assembly of photovoltaic cells according to the first embodiment;

Figure 8 shows schematically another alternative embodiment of a conductive connection element of an assembly of photovoltaic cells according to the first embodiment;

Figure 9 shows schematically an example of an assembly of photovoltaic cells according to a second embodiment;

FIG. 10 illustrates an example of a collecting structure of a photovoltaic cell according to a third embodiment; and

Figure 11 shows schematically an example of a photovoltaic device according to a fourth embodiment.

Description of the embodiments

The same elements have been designated by the same references in the different figures. In particular, the structural and / or functional elements common to the various embodiments may have the same references and may have identical structural, dimensional and material properties.

For clarity, only the steps and elements useful for understanding the described embodiments have been shown and are detailed. In particular, the production of the elementary photovoltaic cells constituting the described assemblies has not been detailed, the production of such cells being within the reach of the skilled person from the indications of this description.

Unless otherwise specified, when reference is made to two elements connected to each other, this means directly connected without intermediate elements other than conductors, and when reference is made to two elements connected or coupled together, this means that these two elements can be connected or be linked or coupled via one or more other elements.

In the following description, when reference is made to qualifiers of absolute position, such as the terms "front", "rear", "top", "bottom", "left", "right", etc., or relative, such as "above", "below", "upper", "lower", etc., or to orientation qualifiers, such as "horizontal", "vertical", etc. ., reference is made unless otherwise specified in the orientation of the figures, it being understood that, in practice, the devices described can be oriented differently.

Unless specified otherwise, the expressions "approximately", "approximately", "substantially", and "of the order of" mean to the nearest 10%, preferably to the nearest 5%, or, when they refer to angular or similar orientations, to within 10 °, preferably to within 5 °.

Figure 1 schematically shows an example of an assembly 100 of photovoltaic cells 102 of a photovoltaic panel. Figure 1 includes a view (A) and a view (B) of the assembly. View (A) is a partial sectional view of the assembly 100 along the plane AA of view (B). View (B) is a perspective view of the rear face of the assembly 100. The photovoltaic cells 102 of the assembly 100 are for example identical, apart from the manufacturing dispersions. In the example of FIG. 1, the cells 102 have the form of rectangular plates and are arranged side by side in the same plane. Neighboring cells have their long sides substantially parallel and facing each other, and have their short sides aligned.

Thereafter, we will call "length" of a photovoltaic cell of a cell assembly the dimension of this cell in the direction of alignment of the cells of the assembly, and "width" of the cell its dimension in a direction orthogonal to the direction of alignment of the cells. In other words, in the example of FIG. 1, the length of a cell corresponds to the dimension of its short sides and the width of a cell corresponds to the dimension of its long sides.

In the example of Figure 1, the width of the cells can be between 51 mm (about 2 inches) and 210 mm (about 8 inches), for example of the order of 156 mm (about 6 inches) . The length of the cells is for example between one tenth of their width and their width.

Each cell 102 comprises a P-type doped semiconductor plate 104 comprising, on the side of its front face, that is to say its upper face in the orientation of the view (A) of FIG. 1, a layer 106 doped with type N. The semiconductor plate 104 is for example made of silicon. The semiconductor plate 104 can be monocrystalline or multicristalline. The thickness of the plate 104 is for example between 100 and 300 μm. The layer 106 extends vertically from the front face of the plate 104, for example over a thickness of between 0.05 and 0.1 μm. In top view, the layer 106 extends for example over substantially the entire surface of the semiconductor plate 104. The layer 106 can be structured on the side of its front face so as to trap the sunlight. The layer 106 can also be covered with an anti-reflective layer (not shown).

Each cell 102 further comprises conductive collecting structures 108 and 110 respectively disposed on and in contact with the front face and under and in contact with the rear face of the semiconductor plate 104. In Figure 1, the collecting structures 108 and 110 have not been detailed. The front face collector structure 108 may be a metallic layer, for example of aluminum or silver, perforated to allow sunlight to reach the front face of the semiconductor plate 104. By way of example, with a view to above, the surface of the semiconductor plate 104 covered by the metal layer forming the collecting structure 108 is less than 10% and preferably less than 5% of the total surface of the semiconductor plate 104 so as to allow most of the radiation incident solar to reach the face of the semiconductor plate 104. For example, the collecting structure 108 has, seen from above, the shape of a comb whose teeth form with the front face of the layer 106 electrical contacts regularly distributed over the entire front face of the layer 106. As a variant, the front face collecting structure 108 is a layer of a transparent conductive material, for example of tin and indium oxide, extending continuously over substantially the entire front face of the semiconductor plate 104.

The rear face collector structure 110 may be a metal layer, for example aluminum or silver, extending continuously over substantially the entire rear face of the semiconductor plate 104. If necessary, if desired that the back side of the photovoltaic cells it also collects light, for example by reflection on surfaces arranged at the rear of the panel, the rear face collecting structure 110 can be an openwork metallic layer or a layer of a transparent conductive material. In this case, the semiconductor plate 104 may comprise, on the side of its rear face, a doped layer (not shown) of conductivity type opposite to that of the plate 104, that is to say of type N in this example. , extending for example over the entire surface of the plate 104. This is called a bifacial photovoltaic cell.

In the example of Figure 1, the semiconductor plate 104 comprises, on the side of its rear face, a P-type region 112 doped with a doping level higher than that of the plate 104. The rear face collector structure 110 is in contact with the plate 104 through the region 112. For example, the structure 110 is a layer of aluminum, and the region 112 results from a diffusion of the aluminum in the plate 104 .

In the case of bifacial photovoltaic cells, the collecting structure 110 is for example made of silver.

In the example of Figure 1, each cell 102 comprises a plurality of connection pads 114 arranged on and in contact with the front face collecting structure 108, and a plurality of connection pads 116 arranged on and in contact with the rear face collecting structure 110. The connection pads 114 and 116 are for example based on silver and / or tin. The studs 114 on the one hand, and the studs 116 on the other hand, are aligned in the direction of the width of the cell.

The lateral dimensions of the connection pads 114 and 116 are small compared to those of the cells. For example, the connection pads 114 and 116 each have a length less than half the length of the cells. and a width less than 10% of the length of the cells. The lengths and widths of the studs 114 and 116 are for example less than 3 mm.

The cells of the assembly of Figure 1 are connected in series by elongate conductive elements 120, for example conductive tapes or conductive son, for example copper. Each conductive element 120 extends longitudinally in the direction of the length of the cells. Each conductive element 120 has one end connected and preferably electrically connected, for example welded, to a stud 116 on the rear face of a cell and at its other end welded to a stud 114 on the front face of a neighboring cell. In the case where the conductive elements 120 are tapes, the width of the tapes can be between 0.5 and 3 mm. The thickness of the conductive tapes is for example between 50 and 200 μm. In the case where the conductive elements 120 are wires, the diameter of the wires can be between 50 and 500 μm. In the example shown, each cell 102 comprises three front face connection pads 114 regularly aligned and regularly distributed in the direction of the width of the cell, and three rear face connection pads 116 regularly aligned and distributed in the direction of the width of the cell. Two neighboring cells are then connected by three parallel conductive elements 120, regularly distributed in the direction of the width of the cells. The number of studs

114/116 per cell and the number of conductive elements 120 connecting two neighboring cells together may, however, be different from three. For example, each cell 102 comprises seven front face connection pads 114 regularly aligned and evenly distributed in the direction of the width of the cell, and seven rear face connection pads 116 regularly aligned and distributed in the direction of the width of the cell. Of them neighboring cells are then connected by seven parallel conductive elements 120, regularly distributed in the direction of the width of the cells.

The rear face connection pads 116 of each cell are arranged near the edge furthest from the neighboring cell to which these pads are connected by conductive elements 120. The pads 116 of each cell are thus in half of the cell furthest from the neighboring cell connected to these pads. For example, each pad 116 of a cell 102 is located entirely within the 10% of the cell 102 furthest from the neighboring cell connected to the pad. The studs 114 are for example arranged directly above the studs 116.

Due to this arrangement of the pads, each conductive element 120 has, in addition to an oblique part 122 connecting the front face of a cell to the rear face of a neighboring cell, a horizontal free part 124 not welded whose length is greater than half the length of the cells, for example of the order of the length of the cells.

At the ends (not shown) of the cell repetition, the connection conductive elements 120 can be connected to other similar assemblies connected in series or in parallel with the assembly 100, or to an electronic device such as a power converter.

In operation, when the cells are exposed to sunlight, the current produced by each cell is collected, on the front side by the collecting structure 108, and, in the case of a bifacial cell, on the back side by the collecting structure 110. The collected current converges towards the pads 114 and travels in the conductive elements 120 towards the pads 116 of the neighboring cell. Figure 2 is a top view of an elementary photovoltaic cell 102 of the assembly 100 of Figure 1, illustrating in more detail an exemplary embodiment of the front face collecting structure 108 and connection pads of front face 114 of the cell.

The collecting structure 108 of FIG. 2 has the shape of a comb comprising a plurality of teeth 203 connected to one another by a collecting strip 201, continuous or discontinuous, extending parallel to a large side (width) of the cell, near an edge of the cell. The width of the collecting track 201 is for example between 50 and 200 μm. The teeth 203 of the comb are formed by conductive strips perpendicular to the strip 201, extending from the strip 201 to the long side of the cell opposite to the strip 201 (in the direction of the length of the cell). The teeth 203 are distributed regularly over the entire width of the cell. Each tooth 203 has for example a width of between 10 and 100 μm and preferably between 20 and 50 μm. The repetition step of the teeth 203 is for example between 1 and 3 mm. The collecting structure 108 of FIG. 2 is for example made of silver or aluminum. The thickness of the structure 108 is for example between 5 and 30 μm. Portions (not shown) of protective layers and / or anti-reflection layers may be present on the front face of the layer 106 between the teeth of the comb. In the example of FIG. 2, the cell comprises seven front face connection pads 114 arranged along the main strip 201 of the comb, regularly distributed along the strip 201. Each stud 114 is partly located on the strip 201.

More generally, the front face collecting structure 108 may have any other form suitable for uniformly collecting the charge carriers generated in the plate semiconductor 104 of the cell, and to make them converge towards the front face connection pads 114 of the cell.

A limitation of the assembly described in connection with Figures 1 and 2 is that it is relatively complex to achieve. Indeed, the welding of the conductive elements 120 to the connection pads 114 and 116 of the elementary cells 102 requires expensive and bulky equipment and is relatively long to produce.

In addition, the welds of the conductive elements 120 to the connection pads 114 and 116 create a rigid mechanical link between the conductive elements 120 and the cells, which can lead to damage in the event of deformation of the photovoltaic panel, due for example to variations in temperature, the force of the wind, or the weight of the snow.

Furthermore, in the case of elementary cells comprising a collecting structure formed by an openwork metal layer, for example of the type described in relation to FIG. 2, the conductive pattern of the collecting structure must be chosen able to converge the charge carriers collected to the corresponding connection pads of the cell. This imposes constraints on the choice of pattern, which are not necessarily compatible with the need to minimize the surface of the semiconductor plate 104 obscured by the collecting structure.

In addition, the presence of ribbons or conductive son

120, relatively thick, on the surface of the cells, degrades the aesthetics of the assembly.

In addition, the surface of the electrical contact zones between the conductive elements 120 and the collector structures and the number of contact points between the conductive elements 120 and the collector structures are relatively weak. The risk of rupture of the electrical continuity between the conductive elements 120 and the collecting structures, and therefore of loss of efficiency of the assembly, is therefore relatively high.

Figure 3 schematically shows an example of an assembly 300 of photovoltaic cells 302 of a photovoltaic panel according to a first embodiment. Figure 3 includes a view (A) and a view (B) of the assembly The view (A) is a partial sectional view of the assembly 300 according to the plane A-A of the view (B). View (B) is a partial top view of assembly 300.

The assembly 300 and the elementary cells 302 of Figure 3 include elements common with the assembly 100 and the elementary cells 102 of Figure 1. These common elements will not be detailed again. In the following, only the differences compared to the example described in relation to Figures 1 and 2 will be highlighted.

The elementary cells 302 of FIG. 3 differ from the elementary cells 102 of FIG. 1 mainly in that they do not include connection pads 114 on their front face collector structures 108, nor connection pads 116 on their rear face collecting structures 110.

In the assembly 300 of Figure 3, the cells 302 are connected in series by perforated conductive sheets 304, for example copper, preferably tinned copper (that is to say covered with an alloy based on tin). Each conductive sheet 304 extends over a part of the front face of a cell, and under a part of the rear face of a neighboring cell. More particularly, each conductive sheet 304 comprises a part 304a in contact, by its rear face, with a part of the collecting structure of the front face 108 of a cell, and a part 304b in contact, by its front face, with a part of the rear face collecting structure 110 of a neighboring cell. Each ply 304 further comprises, between the parts 304a and 304b, an oblique part 304c extending between the long sides facing the two neighboring cells that it connects. Each ply 304 extends, in the direction of the width of the assembly, over substantially the entire width of the cells that it connects. As a variant, the width of the sheet can be limited to only part of the width of the cells. Preferably, the width of the sheet is at least equal to 90% of the width of the cells. By way of example, in each ply 304, each of the parts 304a and 304b of the ply extends, in the direction of the length of the assembly, over a distance ranging from a quarter to three quarters of the length of the cell, starting from the long side of the cell closest to the neighboring cell connected to the same sheet 304.

Note that in the view (B) of Figure 3, for the sake of simplification, only the central web 304 of the assembly portion of the view (A) has been shown.

Perforated conductive layers here means that each layer 304 comprises through openings capable of allowing most of the incident solar radiation to pass in the direction of the semiconductor plate 104. For example, each layer 304 consists of crossed conductive wires forming a grid. By way of example, each sheet 304 is made up of braided conductive wires (not welded) forming a grid. As a variant, each ply 304 consists of a one-piece conductive mesh. Due to the relatively large dimensions of the plies 304 in the direction of the width of the assembly, the thickness of the conductive wires constituting the plies 304 may be small, which has the advantage of giving a great flexibility with plies 304. By way of example, the thickness of the conductive wires constituting plies 304 is between 10 and 500 μm, for example between 50 and 100 μm.

In the example of Figure 3, the conductive layers 304 are in mechanical and electrical contact with the collecting structures 108 and 110 of the cells 302, but are not directly attached to the collecting structures 108 and 110. In particular, the layers 304 are not welded or glued to the collecting structures 108 and 110. Thus, in the event of deformation of the photovoltaic panel, for example under the effect of variations in temperature or due to meteorological phenomena, each layer 304 can slide along front and / or rear faces of the cells which it connects, which makes it possible to maintain the electrical connection between the cells without creating mechanical stresses liable to damage the cells.

In the example of FIG. 3, the assembly 300 is protected, on the front face, by a transparent protective plate 306, for example made of glass or plexiglass, and, on the rear face, by an opaque protective plate or transparent 308. For the sake of simplification, the upper protective plate 306 has not been shown in view (B) of FIG. 3. The photovoltaic cells 302 and the connection plies 304 are for example kept in compression between the protective plates 306 and 308, so as to maintain electrical contact between the connection plies 304 and the cells 302. By way of example, the protective plates 306 and 308 can be fixed to each other and to the assembly of photovoltaic cells 302 and connection plies 304 by a lamination process. The use of a lamination process makes it possible in particular to establish a uniform residual compression stress enduring for a long period of time, typically several years to several decades. More generally, any other fixing means making it possible to keep the cells 302 and the plies 304 in compression between the protective plates 306 and 308 can be used.

An advantage of the assembly of FIG. 3 is that it is simpler to produce than assemblies based on welded conductive tapes or wires of the type described in relation to FIG. 1. Indeed, in the mode of As shown in FIG. 3, the elementary cells 302 and the conductive layers 304 can be positioned using conventional picking and positioning equipment ("pick and place" in English). It will also be noted that the relative positioning of the conductive plies 304 relative to the cells 302 does not require great precision due to the relatively large dimensions of the plies 304.

Furthermore, in the embodiment of Figure 3, each conductive sheet 304 forms with the collecting structures 108 and 110 of the cells that it connects an electrical contact regularly distributed over the entire width of the cells. Thus, in the case of a collecting structure formed by a perforated metal layer in contact with the front or rear face of the semiconductor plate 104, it is not necessary that the conducting elements of the collecting structure converge towards a limited number of connection pads. This is illustrated by the view (B) of FIG. 3, in which the front face collecting structures 108 of the cells have a shape similar to that of FIG. 2, but in which the main bar 201 of the comb has been removed, the teeth 203 of the comb extending from one long side to the other of the cell. In other words, in the embodiment of FIG. 3, each collector structure may consist of a plurality of conductive patterns regularly distributed over one face of the semiconductor plate 104 of the cell, the patterns not necessarily being connected to each other in the absence of the sheet 304. This makes it possible to increase the surface of the semiconductor plate 104 not masked by the collecting structure 108 or 110, and thus increase the efficiency of the cell.

Another advantage of the embodiment of Figure 3 is that the conductive layers 304 can be relatively discreet, or even invisible, even at a relatively small distance, insofar as they consist of very fine conductive son. This improves the aesthetics of the assembly compared to a solution based on ribbons or conductive wires of the type described in relation to FIG. 1.

Another advantage from the point of view of electrical reliability is that the number of contact points and the effective contact surface between the conductive sheet 304 and the collecting structures are very large. This drastically reduces, or even eliminates, the risk of breaking electrical continuity within the assembly.

Note that the first embodiment is not limited to assemblies comprising only cells connected in series, but can be applied more generally to any assembly comprising at least two photovoltaic cells connected in series one to the other.

FIG. 4 schematically illustrates, as a variant, an exemplary embodiment of an assembly 300 comprising a plurality of elementary cells 302 connected in parallel and in series. More particularly, in this example, cells 302 are grouped in pairs of two neighboring cells connected in parallel, the pairs of cells being connected in series with each other. More specifically, in each pair of neighboring cells connected in parallel, an upper conductive sheet 304 connects the front face of the first cell to the front face of the second cell, and a lower conductive sheet 304 connects the rear face of the first cell to the back of the second cell. Two neighboring pairs are in turn connected in series by a conductive sheet 304 connecting the front face of the second cell of the first pair to the rear face of the first cell of the second pair.

Figure 5 is a schematic and partial top view of another example of an assembly of photovoltaic cells according to the first embodiment.

The assembly of Figure 5 includes M strings

300_1, ... 300_M each comprising N photovoltaic cells 302 connected in series, M and N being integers greater than or equal to two. The M strings 300_i (with integer i going from 1 to M) are connected in parallel between main terminals P + and P- of the assembly. In the example shown, the assembly comprises M = 4 strings 300_1, 300_2, 300_3 and 300_4 each comprising N = 8 cells 302. The embodiments described are of course not limited to this particular case.

In top view, the photovoltaic cells are arranged in a matrix according to M rows and N columns. Each row of the matrix corresponds to a rosary 300_i. Each column of the matrix comprises all the cells of the same rank j in the M strings (with j integer ranging from 1 to N).

Each of the strings 300_i corresponds to an assembly identical or similar to the assembly 300 of FIG. 3. However, in the assembly of Figure 5, each conductive sheet 304 connecting to each other two neighboring cells of the same string is common to the M strings 300_i of the assembly. In other words, each conductive sheet 304 extends continuously over substantially the entire height of the assembly in the direction of the columns of the matrix.

Thus, if we consider two columns of row j and j + 1 of the matrix, the same perforated conductive sheet 304 extends over part of the front face of each cell of row j of the matrix, and under a part of the rear face of each cell of row j + 1 of the matrix. Thus, the front faces of the M cells of row j of the assembly are connected to each other and to the rear faces of the M cells of row j + 1 of the assembly by the same conductive sheet 304.

An advantage of the assembly of FIG. 5 is that the electrical connection in parallel of the M strings 300_i is carried out not only at the ends of the strings, but also at the level of each elementary photovoltaic cell of each strand, inside of the matrix, which allows a better distribution of the collected currents.

Another advantage of the assembly of Figure 5 is that it is relatively easy to achieve. For example, cells of the same rank j can be removed and positioned simultaneously by a robot, then an openwork conductive sheet extending continuously over the entire height of the assembly can be positioned, and so on until '' to complete the assembly. It will be noted in particular that the number of conductive plies 304 to be handled is divided by M relative to an assembly of M strings in parallel in which the conductive plies 304 would not be common to the different strings. Figure 6 is a partial sectional view schematically illustrating another example of an assembly 400 of photovoltaic cells 302 according to the first embodiment. The assembly 400 of Figure 6 includes elements common to the assembly 300 of Figure 3. These elements will not be detailed again below. In the following, only the differences between the two assemblies will be highlighted.

In the example of Figure 6, instead of the cells being side by side in the same plane, the neighboring cells overlap. By way of example, in the direction of the length of the assembly, the area of overlap between two neighboring cells has a dimension of between 1 and 10% of the length of a cell. As in the example in FIG. 3, the neighboring cells are connected via an openwork conductive sheet 304 having a first part 304a in contact, through its rear face, with a part of the surface of the collecting structure of front face 108 of a cell, and a second part 304b in contact, by its front face, with a part of the surface of the rear face collector structure 110 of the neighboring cell. In the example of FIG. 6, each ply 304 further comprises, between the parts 304a and 304b, in the zone of overlap or overlap between the two cells which it connects, a part 304c in contact at the same time, by its rear face, with the collecting structure 108 of the first cell, and, by its front face, with the collecting structure 110 of the second cell.

Note that the embodiments of Figures 5 and 6 can of course be combined.

FIG. 7 illustrates an alternative embodiment of a conductive connection sheet 304 of an assembly of photovoltaic cells according to the first embodiment. The tablecloth connection 304 of FIG. 7 can in particular be used in an assembly of the type described above in relation to FIGS. 3 to 6.

In the example of FIG. 7, the ply 304 comprises, in its part 304a, facing the first cell (not shown in FIG. 7) connected to the ply, along the edge of the sheet furthest from the second cell (not shown in FIG. 7) connected to the sheet, a conductive fixing strip 351, and, in its part 304b, facing the second cell connected to the sheet , along the edge of the ply most distant from the first cell connected to the ply, a conductive fixing strip 353.

The conductive fixing strips 351 and 353 are for example metal strips, for example copper, coated with a metal alloy suitable for melting and fusing with the metal of the collecting structures 108 and 110 during the lamination of the plates. protective 306 and 308.

An advantage of the variant of FIG. 7 is that it allows, by fixing the conductive connection plies 304 to the collecting structures of the photovoltaic cells, to further reduce the risk of breaking of electrical continuity within the assembly. Due to the arrangement of the conductive fixing strips along the two edges of the ply parallel to the width of the assembly, a portion of the portion 304a of the ply 304 remains free to move relative to the first cell, and a portion of the part 304b of the sheet 304 remains free to move relative to the second cell. The advantage of flexibility of the assembly and relative mobility of the cells with respect to each other within the assembly (in particular in the direction of the length of the cells) is thus preserved. As an example, the width of each of the conductive fixing strips 351 and 353 (ie in the direction the length of the cells) is less than 20% of the total dimension of the sheet in this direction. Furthermore, although the strips 351 and 353 have been shown in the form of solid conductive strips in FIG. 7, the embodiments described are not limited to this particular case. As a variant, each of the conductive fixing strips 351 and 353 may correspond to an openwork portion of the sheet 304. In other words, each openwork conductive sheet 304 may comprise:

- In the left part of the sheet, a first portion of perforated sheet coated with the metal alloy suitable for melting and fusing with the metal of the collecting structures 108 and 110 during the lamination of the protective plates 306 and 308;

- In the right part of the sheet, a second portion of perforated sheet coated with the metal alloy; and

- In the central part of the sheet, a third portion of perforated sheet not coated with the metal alloy.

FIG. 8 illustrates another alternative embodiment of a conductive connection sheet 304 of an assembly of photovoltaic cells according to the first embodiment Unlike the examples described above in which the conductive sheet 304 had, seen from above, a generally rectangular shape, in the example of FIG. 8, the parts 304a and 304c of the sheet 304 have a serrated or square shape.

More particularly, in this example, the part 304a of the ply 304 comprises, on the side of the edge of the ply most distant from the second cell (not visible in FIG. 8) connected to the ply, a plurality of teeth or slots 305a extending in the direction of the length of the cells, for example regularly distributed over the width of the sheet In addition, in this example, the portion 304c of the sheet 304 comprises, on the side of the edge of the ply furthest from the first cell (not visible in FIG. 8) connected to the ply, a plurality of teeth or slots 305c extending in the direction of the length of the cells, for example evenly distributed over the width of the tablecloth. Between two neighboring teeth 305a of the ply 304, the upper face of the first cell connected to the ply 304 is not covered by the ply. In addition, between two neighboring teeth 305c of the ply 304, the underside of the second cell connected to the ply is not covered by the ply

The conductive patterns of the collector structures of the front face and rear face of the elementary cells are chosen so that each conductive element of the pattern is connected to at least one tooth 305a or 305b of the sheet 304. Such a serrated conductive sheet is for example well suited to the connection of cells provided with collecting structures of the type described below in relation to FIG. 10.

The teeth 305a and 305c each extend for example over substantially the entire length of the part 304a, respectively 304c of the ply, as illustrated in view (A) of FIG. 8. As a variant, the teeth 305a and 305c each extend over a length less than the length of the part 304a, respectively 304c of the ply, as illustrated in view (B) of FIG. 8.

In the example shown in Figure 8, the part 304a and the part 304c of the web are both provided with teeth or slots. As a variant, only one of the two parts 304a and 304c of the ply may be provided with teeth or slots.

An advantage of the variant of FIG. 8 is that it makes it possible to increase the surface of the cells not covered by the plies 304, and therefore the yield of the cells. Furthermore, this variant saves conductive material for producing the plies 304.

Figure 9 is a sectional view schematically and partially illustrating an example of an assembly 600 of photovoltaic cells 302 of a photovoltaic panel according to a second embodiment. The assembly 600 of FIG. 9 comprises elements that are common with the assembly 400 of FIG. 6. These common elements will not be described again below. In the following, only the differences compared to the assembly of Figure 6 will be highlighted.

As in the assembly 400 of Figure 6, the elementary cells 302 adjacent to the assembly 600 of Figure 9 overlap. However, unlike assembly 400, assembly 600 does not include conductive plies connecting two by two in series with neighboring cells.

In the embodiment of Figure 9, the front face collector structure of a cell is directly in contact, mechanically and electrically, with the rear face collector structure of a neighboring cell, in the overlap area between the two cells. This makes it possible to directly ensure the series connection of the cells of the assembly, without elements of intermediate connection between the cells.

In assembly 600, the contacts between the collecting structures of the front and rear face of the cells, in the areas of overlap between neighboring cells, are sliding contacts. In other words, in the area of overlap between two neighboring cells, the front face of the lower cell is not fixed to the rear face of the upper cell. In particular, the front face collecting structure 108 of the lower cell is not welded, nor glued to the conductive structure of the rear face 110 of the upper cell.

Thus, an advantage of assembly 600 is that, in the event of deformation of the photovoltaic panel, for example under the effect of temperature variations during manufacture and in particular during the lamination phase of the protective plates of the panel , or due to meteorological phenomena, each cell 302 can slide along the front and / or rear faces of the neighboring cells to which it is connected, which makes it possible to maintain the electrical connection between the cells without creating mechanical stresses liable to damage cells.

Another advantage of the assembly of FIG. 9 is that it is particularly simple to manufacture insofar as no intermediate connection element and no solder, conductive adhesive or conductive adhesive are provided between the cells. Simple cell assembly equipment which is easy to automate and quick can therefore be used, for example "pick and place" type equipment.

Furthermore, the elimination of the soldering of ribbon or conductive wires on the cells, sources of defects, leads to a better conversion efficiency of the cells, and to better resistance to aging.

In addition, due to the absence of ribbons or conductive wires and connection pads, a large quantity of conductive material can be saved, which reduces the cost price of the cells as well as the carbon footprint associated with the manufacture of cells. A screen printing step generally provided for in the manufacture of a cell of the type described in relation to FIG. 1 to form the connection pads 114, 116 can also be avoided. As in the examples of FIGS. 3 to 8, the elementary cells 302 of the assembly 600 can be maintained by any mechanical support adapted to avoid excessive displacements of the cells with respect to each other, so as to guarantee the maintenance of the electrical connection between the cells. As in the example in FIGS. 3 to 8, the elementary cells 302 of the assembly 600 are for example kept in compression between a protective plate on the front face 306 and a protective plate on the rear face 308.

In the embodiment of FIG. 9, the front face 108 and rear face 110 collecting structures of the cells are chosen such that all the conductive elements of the front face collecting structure 108 of each cell are connected to the rear face collector structure of the upper neighboring cell in the area of overlap between the two cells, and such that all the conducting elements of the rear face collector structure 110 of each cell are connected to the front face collector structure of the cell lower neighbor in the overlap area between the two cells. Preferably, the rear face collecting structure 110 of each cell 302 is a metallic layer, for example made of silver, tin or aluminum, extending continuously over substantially the entire rear face of the cell. The front face collecting structure 108 of each cell is for example an openwork metallic layer, for example made of silver or aluminum, such that all the elements of the conductive pattern of the structure extend up to the overlapping zone of the cell. with the upper neighboring cell For example, the conductive pattern of the front face collecting structure 108 of the elementary cells 302 can be a pattern of the type described above in relation to FIGS. 2 or 3, or even a leaf-shaped pattern of the type described in connection with FIG. 4 of the above-mentioned French patent application No. 16/54518.

Figure 10 is a top view of an elementary photovoltaic cell 602 of an assembly of photovoltaic cells according to a third embodiment. The elementary cell 602 of FIG. 10 comprises elements common with the elementary cells 102 and 302 described above. These common elements will not be described again below. In the following, only the differences compared to the elementary cells 102 and 302 will be highlighted.

Cell 602 of Figure 10 differs from cells

102 and 302 described above mainly by the shape of its front face collecting structure 108.

The front face collector structure 108 of the cell 602 is formed by an openwork metallic layer, for example made of silver or aluminum, in contact with the front face of the semiconductor layer 106 of the cell.

The collecting structure 108 of the cell 602 consists of one or more occurrences of an elementary conductive pattern 610 comprising, in top view:

- A straight main conductive strip 614 extending longitudinally from an edge of the cell, in the direction of the length of the cell, over about half of the length of the cell; and

- A plurality of secondary conductive strips 616 of width less than that of the main strip 614, extending from the periphery of the strip 614.

In the example shown, the collecting structure 108 of the cell 602 comprises 5 occurrences of the elementary conductive pattern 610, regularly distributed over the entire width of the cell. The main conductive strips 614 of the different occurrences of the elementary pattern 610 all start from the same edge of the cell (the right edge in the orientation of FIG. 10). The neighboring occurrences of the elementary pattern 610 have secondary conductive bands which meet, so that the whole of the conductive pattern of the collecting structure 108 is continuous.

For example, the main conductive strip 614 of the elementary pattern 610 has a width of between 0.2 and 1 mm. Each secondary conductive strip 616 of the elementary pattern has for example a width of between 10 and 100 μm. The width of the secondary conductive strips is for example between 10 and 50 μm. The thickness of the structure 108 is for example between 10 and 30 μm.

In this example, seen from above, each elementary conductive pattern 610 is inscribed in a rectangle 612 having two sides 612a and 612b substantially parallel to the length of the cell, of length substantially equal to the length of the cell, and two sides 612c and 612d substantially parallel to the width of the cell, of length substantially equal to the width of the cell or to a submultiple of the width of the cell. The main conductive strip 614 extends from the center of the side 612c, orthogonally to the side 612c, in the direction of the side 612d, over approximately half the length of the sides 612a and 612b. The secondary conductive strips 616 extend from the longitudinal edges of the main strip 614 and from the end of the main strip 614 opposite the side 612c, to the sides 612a, 612b and 612d of the rectangle 612. The secondary conductive strips 616 have their ends opposite to the main conductive strip 614 evenly distributed along the sides 612a, 612b and 612d of the rectangle

612. The conductive pattern 610 is for example symmetrical with respect to the central longitudinal axis of the conductive strip main 614. In this example, the conductive pattern 610 comprises a plurality of curved secondary conductive strips 616 extending from the end of the strip 614 opposite the side 612c, towards the side 612d and half of the sides 612a and 612b the furthest from the side 612c, and forming with the main strip 614 a dandelion seed-shaped pattern. The conductive pattern 610 of FIG. 10 further comprises a plurality of secondary rectilinear conductive strips 616 substantially orthogonal to the main strip, extending at regular spacing on either side of the main strip 614, from the longitudinal edges of the main strip 614 to the sides 612a and 612b of the rectangle 612. The lengths of the secondary conductive strips 616 of the pattern 610 are all of the same order of magnitude. By way of example, the lengths of the secondary conductive strips 616 of the pattern are all equal to plus or minus 30%.

Thus, an advantage of the elementary conductive pattern 610 of FIG. 10 is that all the charges collected by the secondary conductive strips 616 at the periphery of the rectangle 612 cover substantially the same distance via the secondary conductive strips 616 before reaching the strip main conductor 614. This results in a particularly efficient collection of the carriers generated by the light on the surface of the cell and a particularly homogeneous distribution of the collected current, which makes it possible to improve the efficiency of the cell.

A collecting structure identical or similar to the structure 108 of FIG. 10 can also be used as a collecting structure on the rear face 110 of a photovoltaic cell.

The photovoltaic cell 602 of Figure 10 can be used in any type of cell assembly photovoltaic. By way of example, the cell 602 can be used in an assembly of the type described in relation to FIG. 1, in which case connection pads 114 can be placed on and in contact with the upper face of the main conductive strip 614 of each elementary conductive pattern 610 of the collecting structure 108, for example in the vicinity of the side 612c of the pattern. As a variant, the cell 602 can be used in an assembly of the type described in relation to FIG. 3 or 4, or also in an assembly of the type described in relation to FIG. 9, in which case the connection pads 114 can be omitted.

FIG. 11 illustrates an example of a photovoltaic device 700 according to a fourth embodiment. Figure 11 includes a view (A) and a view (B) of the device. The view (A) is a schematic perspective view of the front face of the device, and the view (B) is an enlarged partial sectional view of the device according to the plane B-B of FIG. (A).

The device 700 of Figure 11 has the shape of a corrugated plate, and comprises a plurality of elementary cells 702 connected in series. The elementary cells 702 of the device 700 are for example cells identical or similar to cells 102, connected in series by conductive elements in a similar manner to what has been described in relation to FIG. 1. As a variant, the elementary cells 702 of the device 700 are cells identical or similar to the cells 302, connected in series by perforated conducting sheets in a similar manner to what has been described in relation to FIGS. 3 to 8. The elementary cells 702 of the device 700 can also be cells identical or similar to cell 602 in FIG. 10, connected in series by conductive tapes or by perforated conductive plies.

In the example of FIG. 11, the direction of the undulations of the device 700 is parallel to the length of the assembly of cells 702. In other words, the elementary cells 702 are slightly curved in the direction of their length so to match the curvature of the device, but are not curved in the direction of their width.

Preferably, the length of each cell is relatively small compared to the minimum radius of curvature of the device, for example between one tenth and one twentieth of the minimum radius of curvature of the plate for cells of thickness of the order of 200 ym. In this way, the curvature of cells 702 remains limited. However, provision may be made to use thinner cells, for example of thickness between 80 and 120 μm, so as to be able to increase their length. By way of example, for cells with a thickness of the order of 80 μm, the length of the cells can be between one third and one fifth of the minimum radius of curvature of the plate.

In the example of FIG. 11, the device comprises a transparent corrugated front face protection plate 704, for example made of glass or plexiglass, and a corrugated or opaque rear protective face plate 706. At least one of the protective plates 704 and 706 is a rigid plate, so as to obtain a photovoltaic panel in the form of a rigid corrugated plate.

For example, the protective plates 704 and 706 can be fixed to each other and to the assembly of photovoltaic cells 702 by a lamination process. More generally, any other suitable method can be used. A bonding and / or filling material, not shown, can optionally be provided between the protective plates. 704 and 706, in particular at the periphery of the assembly to seal the assembly.

In view (B) of Figure 11, there is shown schematically electrical connection links 708 connecting the front face of each cell to the rear face of the neighboring cell. As indicated above, it will be understood that these connections may correspond to conductive elements as described in relation to FIG. 1, or to conductive layers as described in relation to FIGS. 3 to 8.

An advantage of the device 700 of FIG. 11 is that it can directly be used as a covering element of a building, for example in replacement of traditional tiles or slates. Preferably, the height and spacing of the corrugations is compatible with traditional covering elements such as tiles, so that the panel 700 can be used in combination with such traditional covering elements. By way of example, the height (or amplitude) of the undulations is between 5 and 15 cm, and the pitch (or period) of the undulations is between 15 and 30 cm.

Alternatively, the device 700 may be in the form of a curved plate, for example in the form of a single tile (that is to say comprising a single period of undulation).

Various embodiments and variants have been described. Those skilled in the art will understand that certain features of these various embodiments and variants could be combined, and other variants will appear to those skilled in the art. In particular, the embodiments described are not limited to the examples of dimensions and materials mentioned in the present description. In addition, although the photovoltaic cells described each comprise a P-type doped semiconductor plate 104 provided, on the front face, with an N-type doped layer, alternatively, each cell can comprise a doped semiconductor plate type N equipped, on the front face with a doped layer of type P.

Claims

1. Photovoltaic device (300; 400) comprising a juxtaposition of elementary cells (302) connected in series by openwork conductive layers (304).

2. Device (300; 400) according to claim 1, wherein each conductive sheet (304) has a grid shape.

3. Device (300; 400) according to claim 2, wherein each conductive sheet (304) consists of a plurality of braided conductive son forming a grid, or a monobloc grid.

4. Device (300; 400) according to any one of claims 1 to 3, in which each conductive sheet (304) is in contact on the one hand, by its rear face, with a first collecting structure (108) opposite before a first cell and on the other hand, by its front face, with a second collecting structure (110) on the rear face of a second cell close to the first cell.

5. Device (300; 400) according to claim 4, wherein the conductive sheets (304) are not fixed to the first (108) and second (110) collecting structures.

6. Device (300; 400) according to claim 4, in which each conductive sheet (304) is fixed to the first collecting structure (108) by its edge farthest from the second cell, and to the second collecting structure (110 ) by its edge furthest from the first cell.

7. Device (300; 400) according to any one of claims 4 to 6, in which the first structure collector (108) is a discontinuous conductive pattern formed in a metal layer disposed on and in contact with the front face of a semiconductor plate (104) of the first cell.

8. Device (300) according to any one of claims 1 to 7, wherein the neighboring cells (302) are arranged side by side in the same plane.

9. Device (400) according to any one of claims 1 to 7, in which the neighboring cells (302) overlap.

10. Device (300; 400) according to any one of claims 1 to 9, in which each ply (304) has a width substantially equal to the width of the elementary cells (302).

11. Device (300; 400) according to any one of claims 1 to 10, in which each ply (304) has a length of between one quarter and three quarters of the length of the elementary cells (302).

12. Device (300; 400) according to any one of claims 1 to 11, in which the elementary cells (302) and the conductive layers (304) are disposed between a transparent front face protection plate (306) and a rear face protection plate (308).

13. Device (700) according to any one of claims 1 to 12, in the form of a curved or corrugated plate.

14. Assembly comprising a plurality of photovoltaic devices (300_1, 300_2, 300_3, 300_4) according to any one of claims 1 to 13 connected in parallel between first (P +) and second (P-) terminals of the assembly, in which each conductive sheet (304) connecting to one another two neighboring cells (302) of the same photovoltaic device (300_i) is common to all the photovoltaic devices (300_i) of the assembly .