FR3026229A1 - PHOTOVOLTAIC PHOTOCOLTAIC CELL WITH REAR-BACK CONTACTS, PHOTOVOLTAIC MODULE AND METHOD OF MANUFACTURING SUCH A MODULE - Google Patents

Abstract

The invention relates to a photovoltaic cell (1) with interdigitated contacts on the rear face, comprising: a substrate (10) of monocrystalline silicon comprising, on the same main face, said back face, an alternation of regions (13a) doped according to a first type of doping and doped regions (13b) according to a second type of doping opposed to the first type, - an electrically insulating passivation layer (14) extending on the rear face of the substrate (10), - a plurality of metal fingers (15a, 15b) extending in a longitudinal direction on each doped region (13a, 13b) of the first type and the second type, through the passivation layer (14), - a plurality of electrically conductive wires (17) extending on the rear face of the cell transversely to said alternating regions (13a, 13b), each wire electrically connecting either the metal fingers (15a) of each doped region (13a) of the first type or the metal fingers lugs (15b) of each region (13b) doped second type, each wire being in contact with an electrically insulating area of the rear face between two successive metal fingers electrically connected by said wire. The invention also relates to the manufacture of a module comprising at least two such cells.

Description

BACKGROUND OF THE INVENTION The present invention relates to a photovoltaic cell with rear-panel contacts, a module comprising at least two such cells, and a method for producing a photovoltaic cell with rear-panel contacts. manufacture of such a module.

BACKGROUND OF THE INVENTION A homojunction photovoltaic cell comprises a junction formed in the same semiconductor material and for directly converting the received photons into an electrical signal. Homojunction is typically formed in a crystalline silicon substrate at the junction between two regions of the substrate having opposite doping types (n and p). More particularly, homojunction can be obtained from a silicon substrate having a given type of doping (for example n-type doping) and in which a doped zone is formed according to a doping type opposite to that of the substrate ( for example p-type doping). This doped zone, commonly called emitter, is generally formed from the front face of the substrate, corresponding in principle to the face of the substrate for receiving solar radiation. However, in some cases, it may also be formed from the rear face of the substrate, that is to say generally the face opposite to that receiving solar radiation. A doped zone of the same type as the substrate is also provided to form a repulsive electric field.

The conversion efficiency of the homojunction photovoltaic cells is generally limited by recombination losses at the front and / or rear faces of the substrate and by optical losses related to the presence of metallizations on the front face. It is known to minimize these losses by developing a suitable cell architecture having the doped zones (transmitter and repulsive electric field) and the metal fingers (anode and cathode) associated for the collection of charges at the rear face. This cell architecture is commonly called IBC (abbreviation of the English term "lnterdigitated Back Contact cell") or RCC (acronym for the term "Rear Contact Cell"). The doped zones are generally arranged so as to form two interdigitated combs. Sunpower offers photovoltaic cells based on such architecture [1]. The manufacture of the photovoltaic cell, in this case, has metallizations developed by electrolytic deposition of copper with the presence of two bus bars, respectively present at each end of the rear face of the cell. the function of the bus bars is to collect the current from the metal fingers of the same polarity and to receive the metal interconnection ensuring the connection between cells. The setting in module is thus carried out by interconnections of the cells, via copper strips thermally welded to the bus bars of adjacent cells for putting the cells in series. However, this technique is complex and expensive, especially because of the electrolytic deposition which must be implemented with great precision and which requires many steps.

Alternatives include metallization by printing of inks or metal pastes, usually silver-based, for fingers and bus bars. Currently, the ISC Institute Konstanz communicates performance performance greater than 21% by printing screen-printed contacts with the presence of six bus bars on the back (technology ZEBRATM [2]). However, in this case, setting the module appears complex because the welding of the ribbons on the bus bars induces a significant curvature of the cell. This constraint hinders the emergence of this approach although conductive glue type connectors could limit the generation of such a curvature. Another constraint related to the use of screen printing pastes (which are mainly based on silver) is its cost, which depends directly on the quantity deposited. One solution could be to replace the copper strips with electrically conductive son distributed on the rear face of the cell, to allow better extraction of the current and relax the conduction constraints of the metal fingers. It would then be possible to reduce the amount of money deposited by a factor of 2 to 4. Different concepts of wire interconnection have been described for cells with two-sided metallizations, such as the SmartVVire Connection Technologyn "(SVVCT) from Meyer Burger Technology AG [3] or the Schmid Multi Busbar ConnectorTM [4]. In the Meyer Burger Technology AG solution, the cell no longer includes continuous bus bars as in the Schmid solution, but a direct solder of the wires to the metal fingers.Because of the limited electrical conductivity of the wires, it is necessary to to use a plurality of wires (typically between 5 and 30) in order to extract the current without resistive losses However, given the small width of the interdigitated doped zones in the rear face of the cell, it would not be possible to deposit a thread on each of these doped zones.

BRIEF DESCRIPTION OF THE INVENTION An object of the invention is to overcome the aforementioned drawbacks and to design a photovoltaic cell with interdigital contacts on the rear face which is simpler and less expensive to manufacture, which has a better flatness and which allows extraction powerful power. According to the invention, there is provided a photovoltaic cell with interdigitated contacts on the rear face, comprising: a monocrystalline silicon substrate comprising, on the same main face called the back face, an alternation of doped regions according to a first type of doping and doped regions according to a second type of doping opposed to the first type, - an electrically insulating passivation layer extending on the rear face of the substrate, - a plurality of metal fingers extending in a longitudinal direction on each doped region of the first type and the second type, through the passivation layer, - a plurality of electrically conductive son extending on the rear face of the cell transverse to said alternating regions, each wire electrically connecting the metal fingers of each doped region of the first type either the metal fingers of each doped region of the second type, each wire both in contact with an electrically insulating area of the rear face between two successive metal fingers electrically connected by said wire. According to one embodiment, each metal finger extends longitudinally continuously over a doped region of the first and second types, and said electrically insulating zone comprises an electrically insulating pad covering each metal finger at the location of a wire. electrically connecting the metal fingers of the doped regions of the second and the first type, respectively. Particularly advantageously, said electrically insulating pad is made of a dielectric material, organic and / or inorganic. According to another embodiment, each metal finger extends longitudinally discontinuously on a doped region of the first or second type, so as to form portions of fingers separated by inter-finger intervals, inter-finger intervals formed on a doped region of the first type being shifted in the longitudinal direction with respect to inter-finger intervals formed on a doped region of the second adjacent type, each electrically insulating region comprising a region of the passivation layer located in each of said inter-finger intervals . Optionally, an electrically insulating pad extends in said inter-finger intervals on the passivation layer.

Said pad advantageously comprises an inorganic dielectric material or an organic dielectric material, optionally loaded with an inorganic material. According to one embodiment, each doped region of the first and / or second type extends longitudinally in a continuous manner.

Alternatively, each doped region of the first and / or second type extends longitudinally discontinuously, so as to form portions of doped regions separated by inter-region intervals coinciding with inter-finger intervals. . Another object relates to a photovoltaic module comprising at least two photovoltaic cells as described above, said cells being electrically interconnected by the electrically conductive wires. According to one embodiment, the doped regions of the first type and the second type are asymmetrically distributed on the rear face of each cell, and two adjacent cells are arranged with an orientation of 180 ° relative to each other. the other. According to another embodiment, two adjacent photovoltaic cells have electrically insulating areas offset so that a wire connecting the doped regions of the first type of a cell also connects the doped regions of the second type of an adjacent cell. Another object relates to a method of manufacturing a photovoltaic module, comprising: - supplying at least two photovoltaic cells as described above, - setting up a plurality of electrically conductive wires on the face Rearwardly of said cells transverse to said alternating regions, each wire electrically connecting the metal fingers of the regions of a doped cell of the first type with the metal fingers of the regions of an adjacent doped cell of the second type, each wire being in contact with a zone; electrically insulating the rear face of each cell between two successive metal fingers electrically connected by said wire. According to one embodiment, before the introduction of the son, one forms on each metal finger doped regions of the first, respectively the second type, an electrically insulating pad at the location of a wire connecting the metal fingers of the regions doped with the second and the first type, respectively. Advantageously, said electrically insulating pad is formed by screen-printing an organic dielectric material, optionally loaded with an inorganic material, said deposit being made during the manufacture of each photovoltaic cell or between said manufacture and the installation. electrically conductive wires. Alternatively, said electrically insulating pad is formed by screen-printing an inorganic dielectric material, said deposit being made during the manufacture of each cell. Advantageously, several deposition and annealing steps of said dielectric material are used. The manufacture of each cell advantageously comprises: the provision of a monocrystalline silicon substrate comprising, on the same main face called the back face, an alternation of doped regions according to a first type of doping and doped regions according to a second type of doping opposed to the first type, - the formation of an electrically insulating passivation layer on the rear face of the substrate, - the silkscreen formation of a plurality of metal fingers extending in a longitudinal direction on each doped region of the first type and or the second type, through the passivation layer. According to one embodiment, during the manufacture of each cell, the metal fingers are formed discontinuously on each doped region of the first type and / or the second type. According to another embodiment, during the manufacture of each cell, the doped regions of the first type and / or the second type are formed longitudinally discontinuously on the rear face of the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the invention will emerge from the detailed description which follows, with reference to the accompanying drawings in which: - Figure 1 is a sectional view of a photovoltaic cell before the realization of the fingers FIG. 2 is a conventional metallization diagram in plan view for a type I photovoltaic cell BC with two bus bars on either side of the cell, FIGS. 3A and 3B are metallization diagrams in FIG. top view of a cell according to a first embodiment of the invention and a variant of this first embodiment, respectively, - Figures 4A and 4B are sectional views of the metallization schemes of Figures 3A and 3B, FIG. 5 is a metallization diagram in plan view of a cell according to a second embodiment of the invention, FIG. 6 is a sectional view of the metallization diagram. FIG. 7 is a metallization diagram in plan view of a cell according to a third embodiment of the invention; FIG. 8 is a sectional view of the metallization diagram of FIG. FIG. 9 is a basic view of the assembly of several photovoltaic cells of the type of FIGS. 3A and 4A so as to form a module, FIG. 10 is a basic view of the assembly of several photovoltaic cells. of the type of FIGS. 5 and 6 so as to form a module; FIG. 11 is a basic view of the assembly of a plurality of photovoltaic cells according to a preferred embodiment of the invention so as to form a module. For reasons of readability of the drawings, the figures are not necessarily made to scale.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 is a sectional view of a photovoltaic cell 1 with interdigital contacts on the rear face before the production of the metal fingers. The cell comprises a monocrystalline silicon substrate 10 having, for example, n-type doping.

On the front face, that is to say the main face exposed to solar radiation, the minimization of the recombination of the charge carriers is provided by a layer 11 of slightly doped silicon (n + or p + type) covered with a stack 12 of a silicon oxide layer and an antireflection layer of silicon nitride. The oxide layer has a thickness of a few nm and is typically made by thermal growth; the antireflection layer is generally deposited by PECVD on the silicon oxide layer and has a thickness of about 70 nm. On the rear face of the substrate (main face opposite to the front face), elongate caissons 13a, 13b are alternately formed, respectively doping P + (commonly called transmitter) and N + (commonly called BSF, acronym for the Anglo-Saxon term "Back Surface Field "). The width of each box 13a (designated by the reference VVp + in Figure 1) is between 800 pm and 2000 pm. The width of each well 13b (denoted by the reference VVn + in FIG. 1) is between 200 μm and 600 μm. These two boxes are generally separated by an undoped area whose width (designated by the reference d in Figure 1) is between 20 pm and 500 pm. Alternatively (not shown), the two boxes could also be in contact with each other. In this case, there is no intermediate undoped zone. The choice of these respective widths depends on the metallization technique used, the alignment accuracy of the technologies employed and the electrical resistivity of the substrate 10.

The formation of the alternating n + and p + boxes can be carried out in various ways known to those skilled in the art and which will therefore not be described in detail here. A stack 14 of a silicon oxide layer and a silicon nitride layer extends on the rear face of the substrate 10. Alternatively, other dielectric materials may be employed, such as Al 2 O 3, SiC , AIN. This stack fulfills a passivation function. To collect the photogenerated charges, metal fingers, commonly called "fingers" according to the English terminology (not shown in Figure 1) are formed on each of the caissons 13a, 13b to form an electrical contact with the respective box and s' extend through the dielectric stack 14. The metal fingers formed on the caissons 13a form the anode and the metal fingers formed on the caissons 13b form the cathode. In the present text, the term "length" of the cell means the longitudinal direction of the boxes and "width" the direction transverse to said boxes.

FIG. 2 illustrates, in plan view, a metallization scheme corresponding to the case where the collection of charges would be ensured by bus bars at both ends of the cell, according to a known technique. Asymmetry in the formation of the p + and n + boxes is generally necessary to allow the collection of minority carriers at the junction. Thus, it is ensured that the n + boxes and the corresponding metal fingers are in electrical contact with the bus bar Bn + but not with the bus bar Bp +, and vice versa. In this case, the metal fingers n + and p + must conduct the electric current over a length corresponding to the length of the substrate (about 150 mm in general). Finger width constraints also create constraints on the width of the doped wells and therefore require more critical alignment tolerances. The invention proposes to eliminate said bus bars for each cell and to use a plurality of electrically conductive wires, generally based on copper (with possibly a coating improving the weldability of these wires on the metal fingers), to achieve both the collection of the current of the metal fingers of the same polarity for a cell and to achieve the interconnection between two cells (said wires thus also replace the copper ribbon), which makes it possible to limit the soldering surface and consequently the curvature of the cell. Due to the limited electrical conductivity of the wires, it is necessary to use a plurality of wires (typically, between 5 and 30 per cell) to extract the current without resistive losses. Because of the respective widths of the doped caissons (about 1500 pm and 500 pm), it would not be possible to deposit such a wire on each caisson doped in the direction of the length. This would be especially complex on the BSF casings (13b in the diagram) which are of reduced width compared to the transmitting caissons.

The electrically conductive wires are positioned transversely to the doped boxes n + and p +, in a direction substantially perpendicular to the longitudinal direction of said boxes. According to the mechanical tension applied to each wire during its placement on the cell, the wire substantially matches the relief of the rear face of the cell. Therefore, each wire is likely to be not only in contact with the metal fingers it connects, but also with areas of the rear face of opposite polarity. To avoid short-circuiting between the anode and the cathode, it is intended to selectively electrically isolate the areas where the electrically conductive wires are in contact with the cell. This selective isolation can be implemented according to various embodiments which are described below. FIGS. 3A and 4A illustrate, respectively in plan view and in side view, a metallization scheme according to a first embodiment of the invention. The anode (+) wires are shown in solid lines while the (-) cathode wires are shown in broken lines. The doped caissons 13a, 13b extend continuously along the length of the cell 1, alternating between p + doped caissons 13a and n + doped caissons 13b in the transverse direction. Metal fingers 15a, 15b are respectively formed on each box 13a, 13b. Said fingers extend over the entire length of said boxes. In a manner known per se, the metal fingers are formed by serigraphy of an ink or an electrically conductive paste, typically based on silver. The anode and cathode wires 17 extend in the transverse direction of the cell 1 alternately. Each anode wire is welded to each metal finger 15a, while each cathode wire is welded to each metal finger 15b, so as to provide electrical contact between the wire and the corresponding finger. Depending on the mechanical tension applied to each wire during its placement on the cell, the wire substantially matches the relief of the rear face of the cell. Therefore, each wire is in contact alternately with a metal finger of a box doped according to a first type and with a metal finger of a doped box of the opposite type. To avoid the creation of a short circuit between anode wire and a cathode metal pin 15b, an electrically insulating pad 16b is formed on each metal finger 15b at the location provided for said anode wire, before the placing said wire, so as to provide electrical insulation between the cathode metal finger and the anode wire. Similarly, to avoid creating a short circuit between a cathode wire and anode metal finger 15a, an electrically insulating pad 16a is formed on each metal finger 15a at the location provided for said cathode wire, before the introduction of said wire, so as to provide electrical insulation between the anode metal finger and the cathode wire. The pads 16a and the pads 16b are thus staggered on the metal fingers 15a, 15b. Said electrically insulating pads are typically made from a dielectric paste, comprising an organic resin with optionally an inorganic filler (of TiO 2 type, SiO 2 for example) according to the type of annealing performed later. Thus, with low temperature annealing, the integrity of the resin is preserved and, if it is dielectric, it can contribute to the electrical insulation either alone or with a dielectric inorganic filler. On the other hand, with high temperature annealing, the resin is burned. In this case, therefore, it is necessary to include inorganic fillers which resist the temperature and which will ensure the function of electrical insulation. The dielectric paste may also be formed solely of a dielectric organic resin, for example an epoxy resin. After making the metal fingers, said electrically insulating pads are formed by an additional step of screen-printing an electrically insulating paste. In the case where the pads are in an inorganic dielectric material, an annealing will be carried out during or after the annealing of the metal fingers in an infrared type passage oven (in this case, the organic resin may be burned or stored). In the case where the pads are made of an organic dielectric material, a low temperature annealing (of the order of 200 ° C.) is implemented at the end of the manufacturing process of the cell so as to preserve the organic dielectric material. . The length of said electrically insulating pad 16a, 16b is defined according to the alignment tolerances of the wires, and is typically between 1 mm and 5 mm. The width of each insulating pad depends on the quality of the insulation between the wire and the dielectric stack 14 (SiO 2 / SiN) used for passivation. The width of said electrically insulating pad 16a, 16b is greater than the diameter of the wires 17 (which is typically between 100 μm and 500 μm) and preferably less than or equal to the distance between two doped boxes of the same polarity. Thus, in the embodiment of Figures 3A and 4A, when the electrical insulation of the dielectric stack 14 vis-à-vis the wire 17 is of good quality, the insulating pads 16a, 16b may have a relatively limited width. FIGS. 3B and 4B illustrate a variant of the embodiment illustrated in FIGS. 3A and 4A (the same reference signs denoting the same elements), but in which the electrical insulation of the dielectric stack 14 with respect to FIG. thread 17 is of lower quality. In this case, the electrically insulating pads 16a, 16b have a greater width than in the case of Figures 3A and 4A. For these embodiments, the thickness of the insulating pad deposited on the metal fingers must be sufficient to properly cover said finger at the wire location and avoid any risk of short circuit. For this purpose, it will be possible to implement several successive steps of depositing and annealing the dielectric paste. This also makes it possible to avoid short circuit problems (or shunt) related to local pores of the dielectric paste (due in particular to air bubbles trapped during screen printing).

Figures 5 and 6 illustrate, respectively in top view and in side view, a metallization scheme according to a second embodiment of the invention. The anode (+) wires are shown in solid lines while the (-) cathode wires are shown in broken lines. As in the first embodiment, the doped caissons 13a, 13b extend continuously over the length of the cell 1, alternately, in the transverse direction, between p + doped boxes 13a and n + doped boxes 13b. Metal fingers 15a1-15a4, 15b1-15b4 are formed respectively on each box 13a, 13b. In contrast to the first embodiment, said fingers are made discontinuously along said boxes, with a gap devoid of metallization in the longitudinal direction between two adjacent fingers on the same box. Each gap devoid of metallization is positioned to coincide with a region of a box intended to be in contact with a wire connecting the metal fingers of the boxes of opposite polarity, so as to form an electrical insulating zone vis-à-vis said thread. The intervals between the metal fingers of the caissons 13a are offset in the longitudinal direction relative to the intervals between the metal fingers of the caissons 13b. Thus, in a transverse plane, the metal fingers of the boxes 13a are not vis-à-vis the intervals between the metal fingers of the boxes 13b. In other words, the gaps between the metal fingers are staggered. In a manner known per se, the metal fingers are formed by serigraphy of an ink or an electrically conductive paste, typically based on silver. An advantage of this second embodiment is that it requires a smaller amount of ink or electrically conductive paste than in the first embodiment, the surface of the metal fingers being smaller.

The anode and cathode wires 17 extend in the transverse direction of the cell 1 alternately. Each anode wire is welded to a metal finger of each box 13a, while each cathode wire is welded to a metal finger of each box 13b, so as to ensure electrical contact between the wire and the corresponding finger.

Due to the mechanical tension applied to each wire, the wire substantially matches the relief of the rear face of the cell. Due to the discontinuity of the metal fingers, each anode wire is in contact alternately with a metal finger of a box 13a, on which it is advantageously welded, and with the dielectric stack 14 covering an unmetallized area of a box 13b. Similarly, each cathode wire is in physical contact alternately with a metal finger of a box 13b, on which it is advantageously welded, and with the dielectric stack covering an unmetallized zone of a box 13a. In another embodiment, the wires are electrically connected to the metal fingers by bonding rather than welding. Between each electrically conductive wire and the non-metallized zone of a box covered with the dielectric stack 14, there is therefore a contact type MIS (acronym for the term "Metal lnsulator Semiconductor"). The electrical resistance of this contact can be optimized by varying the thicknesses of the dielectric stack 14 or by optimizing the growth or deposition parameters of the layers. If this electrical resistance is considered to provide sufficient insulation of the wire vis-à-vis the non-metallized box, we can be satisfied with this contact MIS. In the opposite case, it will be possible to deposit, on this area of the rear face, an electrically insulating pad as described in the first embodiment before the placement of the wires. The interest of this second embodiment depends on the mechanical tension level of the wire and the alignment accuracy of the latter. Indeed, in this embodiment, the conduction of the current will be provided by the doped caissons in the absence of metallizations. This embodiment will therefore be all the more efficient that the intervals between the metal fingers of the same box will be small, which is possible if the alignment tolerances of the son are low. However, for wide alignment tolerances (that is to say typically greater than 2 mm), imposing high distances between two successive metal fingers on the same box, performance losses related to a strong series electrical resistance are possible. The first embodiment will therefore be more efficient in the latter case. Figures 7 and 8 illustrate, respectively in top view and in side view, a metallization scheme according to a third embodiment of the invention. The anode (+) wires are shown in solid lines while the (-) cathode wires are shown in broken lines. Doped wells 13a1-13a4, 13b1-13b4 extend discontinuously along the length of the cell 1, alternately in the transverse direction between p + doped wells and n + doped wells. In contrast to the first and second embodiments, said boxes are made discontinuously along the length of the cell, so that the intermediate zones between two aligned boxes doped according to a first type are not opposite each other. intermediate zones between two aligned doped boxes of the opposite type to the first. In other words, the intervals between boxes are arranged in staggered rows. Each intermediate zone between two boxes of the same polarity is positioned so as to coincide with a region of the dielectric stack intended to be in contact with a wire connecting the metallic fingers of boxes of opposite polarity, so as to form an insulating zone. electric against said wire.

Metal fingers 15a1-15a4, 15b1-15b4 are respectively formed over all or almost the entire length of each respective box 13a1-13a4, 13b1-13b4. Said metal fingers therefore have the same discontinuity as the boxes. In a manner known per se, the metal fingers are formed by serigraphy of an ink or an electrically conductive paste, typically based on silver.

The anode and cathode wires 17 extend in the transverse direction of the cell 1 alternately. Each anode wire is welded to a metal finger of a box 13a, while each cathode wire is welded to a metal finger of a box 13b, so as to ensure electrical contact between the wire and the corresponding finger. Due to the mechanical tension applied to each wire, the wire substantially matches the relief of the rear face of the cell. Thanks to the discontinuity of the caissons and metal fingers, each anode wire is in alternating contact with a metal finger of a p + doped box, on which it is welded, and with the dielectric stack 14 covering an undoped area. substrate 10 extending between two n + type doped wells. Likewise, each cathode wire is in physical contact alternately with a metal finger of an n + doped box, on which it is soldered, and with the dielectric stack covering an undoped area of the substrate 10 extending between two doped p + type caissons. Between each electrically conductive wire and the undoped area of the substrate 10 covered with the dielectric stack 14, there is therefore a contact type MIS (acronym for the term "Metal Insulator Semiconductor"). The electrical resistance of this contact can be optimized by varying the thicknesses of the dielectric stack 14 or by optimizing the growth or deposition parameters of the layers. If this electrical resistance is considered to provide sufficient insulation of the wire vis-à-vis the non-metallized box, we can be satisfied with this contact MIS. In the opposite case, it will be possible to form an electrically insulating pad as described in the first embodiment before the introduction of the wires. In this third embodiment, the surfaces of the doped caissons are reduced as a function of the alignment accuracy of the wires. Therefore, the cell performance is highly dependent on the ability of the photogenerated carriers over an undoped area of the substrate to diffuse to a doped well. This constraint is related to the quality of the substrate and the passivation of the surfaces. In the case where the distance between the doped caissons is high (that is to say typically greater than 2 mm), it will be preferable to retain the first or the second embodiment. In order to allow the series of IBC cells described above to be put in series, a first production method consists of manufacturing two types of geometry to allow serial connection, so as not to place two doped boxes opposite each other. same type at the interface between two adjacent cells. FIG. 9 illustrates the module formatting of cells according to the first embodiment (FIGS. 3A and 4A). This module implements alternately two metallization schemes (cells 1 and 1 ') making it possible for the interface between two adjacent cells 1, 1', the negative polarity wires of the cell 1 to come into contact with each other. the metal fingers of the boxes of positive polarity of the cell 1 ', and vice versa. With respect to the cell 1, the insulating pads 16a, 16b of the cell 1 'are therefore offset longitudinally. FIG. 9 illustrates the module formatting of cells according to the second embodiment (FIGS. 5 and 6). This module implements alternately two metallization schemes (cells 1 and 1 ') making it possible for the interface between two adjacent cells 1, 1', the negative polarity wires of the cell 1 to come into contact with each other. the metal fingers of the boxes of positive polarity of the cell 1 ', and vice versa. With respect to the cell 1, the zones without metallization of the cell 1 'are therefore offset longitudinally. Although not shown, the modulating of the cells according to the third embodiment (FIGS. 7 and 8) can be carried out according to a similar principle. To simplify the production and to allow the production of a single cell geometry, asymmetry is advantageously created during the formation of n + and p + doped cells in the substrate. In this case, as illustrated in FIG. 11, a cell 1 'is placed relative to an adjacent cell 1, with a rotation of 180 ° C so that the zones of the opposite type can be connected together via the wires. This asymmetry is preferably optimized so as to cover the edges of the cell to the maximum by doped boxes to improve the performance of the cell.

In order to manufacture the module, the photovoltaic cells intended to constitute it are put in place, the cells being at this stage devoid of electrically conductive wires. Once the cells are positioned correctly relative to each other, the electrically conductive wires are put in place so that each wire electrically connects the metal fingers of a given polarity of a cell with the metal fingers of opposite polarity d an adjacent cell. This electrical connection between the son and the fingers can be achieved by welding or gluing.

REFERENCES [1] P. Cousins et al., Generation 3: Photovoltaic Specialists Conference (PVSC), 2010, 35th IEEE [2] A. Halm et al, The Zebra Cell Concept - Large area N-type Solar Photovoltaic Solar Energy Conference and Exhibition, 2012 [3] SmartVVire Connection Technology Brochure, October 2014, http: //www.meyerburger. http://www.schmid-group.com/en/ press-news / a103 / schmid-presents-multi-busbar-connector-at-pvsec.html

Claims (19)

REVENDICATIONS1. Photovoltaic cell (1) with interdigitated contacts on the rear face, comprising: - a monocrystalline silicon substrate (10) comprising, on the same main face, said back face, an alternation of regions (13a) doped according to a first type of doping and regions (13b) doped according to a second type of doping opposed to the first type, - an electrically insulating passivation layer (14) extending on the rear face of the substrate (10), - a plurality of metal fingers (15a, 15b) extending in a longitudinal direction on each doped region (13a, 13b) of the first type and the second type, through the passivation layer (14), a plurality of electrically conductive wires (17) extending over the rear face of the cell transversely to said alternating regions (13a, 13b), each wire electrically connecting either the metal fingers (15a) of each region (13a) doped the first type or the metal fingers (15b) of each r region (13b) doped of the second type, each wire being in contact with an electrically insulating region of the rear face between two successive metal fingers electrically connected by said wire. 2. Cell according to claim 1, wherein each metal finger extends longitudinally continuously over a doped region of the first and second types respectively, and said electrically insulating zone comprises an electrically insulating pad (16a, 16b) covering each finger. metal wire at the location of a wire (17) electrically connecting the metal fingers of the doped regions of the second and the first type, respectively. 3. Cell according to claim 2, wherein said electrically insulating pad (16a, 16b) is of a dielectric material, organic and / or inorganic. The cell of claim 1, wherein each metal finger extends longitudinally discontinuously on a doped region of the first or second type, so as to form finger portions separated by inter-finger intervals, the interstices -digits formed on a doped region of the first type being offset in the longitudinal direction relative to the inter-finger intervals formed on a doped region of the second adjacent type, each electrically insulating region comprising a region of the passivation layer (14) located in each of said inter-finger intervals. 5. Cell according to claim 4, wherein an electrically insulating pad (16a, 16b) extends in said inter-finger intervals on the passivation layer (14). 6. Cell according to claim 5, wherein the pad comprises an inorganic dielectric material or an organic dielectric material, optionally loaded with an inorganic material. 7. Cell according to one of claims 5 or 6, wherein each doped region of the first and / or second type extends longitudinally continuously. 8. Cell according to one of claims 5 or 6, wherein each doped region of the first and / or second type extends longitudinally discontinuously, so as to form portions of doped regions separated by inter-regional intervals. coinciding with inter-finger intervals. 9. Photovoltaic module comprising at least two photovoltaic cells according to one of claims 1 to 8, said cells being electrically interconnected by the electrically conductive son. 20 10. Module according to claim 9, wherein the doped regions of the first type and the second type are asymmetrically distributed on the rear face of each cell, and two adjacent cells are arranged with an orientation of 180 ° relative to each other. to the other. 25 11. Module according to claim 9, wherein two adjacent photovoltaic cells have offset electrically insulating areas so that a wire connecting the doped regions of the first type of a cell also connects the doped regions of the second type of an adjacent cell. . 30 12. A method of manufacturing a photovoltaic module, comprising: - the supply of at least two photovoltaic cells according to one of claims 1 to 8, - the establishment of a plurality of electrically conductive wires (17) on the rear face of said cells transverse to said alternating regions (13a, 13b), each wire electrically connecting the metal fingers of the regions of a doped cell of the first type with the metal fingers of the regions of an adjacent doped cell of the second type, each wire being in contact with an electrically insulating area of the rear face of each cell between two successive metal fingers electrically connected by said wire. 13. The method of claim 12, wherein, before the establishment of the son, is formed on each metal finger doped regions of the first and second type respectively, an electrically insulating pad (16a, 16b) at the location. a wire connecting the metal fingers of the doped regions of the second and the first type, respectively. 14. The method of claim 13, wherein said electrically insulating pad is formed by screen printing of an organic dielectric material, optionally loaded with an inorganic material, said deposit being made during the manufacture of each photovoltaic cell or between said manufacture. and placing electrically conductive wires. 15. The method of claim 13, wherein said electrically insulating pad is formed by screen-printing an inorganic dielectric material, said deposit being made during the manufacture of each cell. 16. Method according to one of claims 14 or 15, wherein it implements several deposition steps and annealing said dielectric material. 17. Method according to one of claims 12 to 16, wherein the manufacture of each cell comprises: - the supply of a substrate (10) of monocrystalline silicon comprising, on the same main face said rear face, an alternation of regions (13a) doped according to a first type of doping and doped regions (13b) according to a second type of doping opposed to the first type, - the formation of an electrically insulating passivation layer (14) on the rear face of the substrate (10) ), the screen-printing formation of a plurality of metal fingers (15a, 15b) extending in a longitudinal direction on each doped region (13a, 13b) of the first type and / or the second type, through the layer passivation (14). 18. The method of claim 17, wherein, during the manufacture of each cell, the metal fingers are formed discontinuously on each doped region of the first type and / or the second type. 19. Method according to one of claims 17 or 18, wherein, during the manufacture of each cell, the doped regions of the first type and / or the second type are formed longitudinally discontinuously on the rear face of the substrate.