Double-sided photovoltaic module

Abstract

A double-sided photovoltaic module (100) comprises at least three photovoltaic junctions that are successively offset along a direction of traversal of the module by radiation. Lateral junctions (1, 2) of the module have bandgap widths that are greater than a bandgap width of a medial junction (3) of said module. Furthermore, the module possesses a configuration with at least two pairs of electrical connection terminals (B1, B1', B2, B2', B3, B3'), and performs voltage matching between branches of junctions that are electrically connected in parallel. The module is thus optimised to produce a greater amount of electricity when it receives radiation (R1, R2) simultaneously on two opposite sides (F1, F2) of said module.

Description

Description Title: BIFACIAL PHOTOVOLTAIC MODULE Technical field

[0001] The present description relates to a bifacial photovoltaic module, as well as to a method of producing electricity which uses such modules. Prior art

[0002] The design and installation of bifacial photovoltaic panels have recently been considered for several markets such as agrivoltaics, building-integrated panels, ground-mounted solar fields, etc. Bifacial photovoltaic panels provide access to particularly high quantities of electricity produced per unit of occupied land area, thanks to the use of both sides of each panel to collect and convert solar radiation. Indeed, one of the sides receives direct and diffuse solar radiation while the other side simultaneously receives diffuse daytime ambient radiation and / or radiation that is reflected or scattered by the ground. The ability of the ground to reflect part of the ambient radiation is called the albedo of this soil. It depends on the nature of the surface soil, for example vegetation, gravel, snow, etc., and helps to send radiation to the face of the photovoltaic panel that is not facing the Sun. The increase in electricity production that is thus made possible by bifacial photovoltaic panels, compared to photovoltaic panels with a single face that is used to collect radiation, can typically be between 5% and 30%.

[0003] Furthermore, to more efficiently transform into electricity the radiation which is incident on a face of a solar panel, it is known to design superpositions of several photovoltaic junctions, the forbidden band width values ​​of which are decreasing in the direction of propagation of the radiation through the junctions which are superimposed. Thus, it is known to arrange on a substrate a first silicon-based photovoltaic junction, which is covered by a second perovskite-based photovoltaic junction, so that the radiation first passes through the perovskite-based junction and then the silicon-based junction. The perovskite-based junction Perovskite is transparent in a spectral range that corresponds to the maximum efficiency of the silicon-based junction, so the structure, often called a tandem, is adapted to more efficiently convert radiation from the solar spectrum.

[0004] For example, the article "Benefits of bifacial solar cells combined with low voltage power grids at high latitudes" by Sami Jouttijàrvi et al., Renewable and Sustainable Energy Reviews 161 (2022), 112354, discloses the use of tandem combinations of silicon and perovskite junctions in bifacial photovoltaic panels: a lower junction is silicon-based and an upper junction is perovskite-based for each radiation that is incident on one of the two faces of the photovoltaic panel. The authors of this article also mention the general advantage of providing pairs of electrical connection terminals that are separately dedicated for each of the photovoltaic junctions, in order to prevent one of the junctions from limiting the electric current that could be produced by the other. A tandem structure is thus provided with four connection terminals.

[0005] Finally, WO 2016 / 198898 A1 discloses a monolithic stack of three photovoltaic junctions for a bifacial module, which comprises a first perovskite-based junction, a silicon-based intermediate junction and a second perovskite-based junction. In this way, the photovoltaic module has an improved bifacial coefficient value, since each radiation propagation direction in the junction stack first passes through a junction with a larger bandgap value before the intermediate junction with a smaller bandgap value. The bifacial coefficient for a bifacial photovoltaic module is defined as the quotient of its photovoltaic conversion efficiency value for radiation incident on the back side of the module by that for radiation incident on the front side of the module. Technical problem

[0006] From this situation, an aim of the present invention is to provide new bifacial photovoltaic panel modules, which are capable of producing quantities of electricity greater than those of the modules known from the prior art.

[0007] Another object of the invention is to provide bifacial photovoltaic panel modules for which the limitation of electric current which is caused by at least one junction on another is avoided.

[0008] Yet another object of the invention is to provide bifacial photovoltaic panel modules which have high values ​​for the bifaciality coefficient. Summary of the invention

[0009] To achieve at least one of these aims or another, a first aspect of the invention proposes a bifacial photovoltaic module, arranged to produce electricity from a first radiation which is incident on a first face of the module and simultaneously from a second radiation which is incident on a second face of the module, parallel and opposite to the first face, during use of the module.

[0010] The module of the invention comprises at least three photovoltaic junctions which each extend parallel to its first and second faces and which are successively offset along a direction of passage of the module between these first and second faces. The three junctions comprise a middle junction, a first lateral junction which is located between the first face and the middle junction, and a second lateral junction which is located between the middle junction and the second face. In this module of the invention, a band gap of the first lateral junction and a band gap of the second lateral junction are each greater than a band gap of the middle junction.

[0011] The bifacial photovoltaic module of the invention further comprises a first pair of electrical connection terminals which is arranged to conduct an electric current produced by one of the photovoltaic junctions, called the first dissociated junction, in accordance with a first electric current flow path which is separated from at least two other junctions. It further comprises at least one other pair of electrical connection terminals which is arranged to conduct another electric current produced by at least one of the photovoltaic junctions other than the first dissociated junction, in accordance with another electric current flow path which is separated from the first dissociated junction.

[0012] In other words, for a three-junction photovoltaic module, the first pair of electrical connection terminals allows the electric current produced by one of these three photovoltaic junctions to be collected without this current passing through the other two junctions, and one or two other electric currents produced by these last two junctions are collected by one or two other pairs of electrical connection terminals without this (these two) other current(s) passing through the first junction. This is why the first junction is said to be dissociated. Thus, the electric current produced by the first dissociated junction is not likely to be limited by the electrical conduction capacity of one of the other junctions.Furthermore, these other junctions may themselves be dissociated, in which case the module has three pairs of electrical connection terminals, or associated, in which case the module may have only two pairs of electrical connection terminals. Thanks to such dissociation of at least one of the photovoltaic junctions of the module, this module is capable of producing greater quantities of electricity.

[0013] Such a principle of dissociation of at least one of the junctions, in accordance with the invention, applies identically to a photovoltaic module with more than three junctions which are superimposed. The invention also covers in particular a photovoltaic module with four or five junctions which are superimposed between the two faces. For a photovoltaic module with five junctions, the module comprises the following ordered sequence from one face to the other: first outer lateral junction, first intermediate lateral junction, middle junction, second intermediate lateral junction then second outer lateral junction. Preferably, the bandgap value of the first (respectively second) outer lateral junction is greater than that of the first (respectively second) intermediate lateral junction, itself greater than that of the middle junction.For a four-junction photovoltaic module, one of the two intermediate junctions in the previous sequence is removed.

[0014] Furthermore, the module of the invention may have a structure that is symmetrical between the two opposite directions of crossing from one face to the other for radiation, by using types of junctions for the side junctions that are similar or have similar characteristics, and by using a structure of electrical connections that is symmetrical for all junctions of the module. In this case, the bifaciality coefficient of the module can be high.

[0015] In particular, the photovoltaic module of the invention may have two or three pairs of electrical connection terminals.

[0016] When the module has three pairs of electrical connection terminals, i.e. it has six terminals, it comprises second and third pairs of electrical connection terminals in addition to the first pair of electrical connection terminals. The second pair of electrical connection terminals is then arranged to conduct a second electric current which is produced by a second of the photovoltaic junctions, called the second dissociated junction and distinct from the first dissociated junction, in accordance with a second electric current flow path which is separate from the first electric current flow path.The third pair of electrical connection terminals is arranged to conduct a third electrical current produced by a third of the photovoltaic junctions, called the third dissociated junction and distinct from each of the first and second dissociated junctions, in accordance with a third electrical current flow path which is separate from the first and second electrical current flow paths.

[0017] For such a configuration with three pairs of electrical connection terminals, the module may comprise three separate substrates: a first substrate which supports the first dissociated junction and the first pair of electrical connection terminals, a second substrate which supports the second dissociated junction and the second pair of electrical connection terminals, and a third substrate which supports the third dissociated junction and the third pair of electrical connection terminals.

[0018] According to an improvement of the invention for a configuration with three pairs of electrical connection terminals, each of the junctions among the middle junction, the first lateral junction and the second lateral junction can be divided into a plurality of cells which are electrically connected in series to form at least one respective branch. Each branch of one of the junctions is separated from each branch of each other junction, and extends between the two electrical connection terminals of the corresponding junction. The module then further comprises two connection nodes electrical which are each connected to one of the electrical connection terminals of each junction, so that all the branches are electrically connected in parallel inside the module. In addition, numbers of cells in each branch are such that a result of multiplying for each branch the number of cells by a value of operating voltage at maximum power relating to the junction of this branch, is substantially equal for all the branches. In this case, the respective values ​​of operating voltage at maximum power which are relative to the first and second lateral junctions, may be different, in particular to correspond to average values ​​of power of the radiation incident on the two faces of the module which are different.These average values ​​may depend in particular on which of the first and second faces of the module is intended to be turned towards the Sun, and on the albedo value of the ground towards which the other face is intended to be turned when the photovoltaic module is used to produce electricity. The respective numbers of cells in the branches of the first and second lateral junctions are then also different, to obtain respective total electrical voltages of all the branches which are substantially equal. Furthermore, dimensions of the cells of the first and second lateral junctions are such that respective branch lengths of these first and second lateral junctions are equal to a length of the median junction, or are divisors of the length of the median junction.The assembly of the module can thus be simplified while optimizing its dimensions, since the junctions then have dimensions which are compatible with the use of a common peripheral frame for mechanical support of the entire module.

[0019] When the module has two pairs of electrical connection terminals, i.e. it has four terminals, the so-called other pair of electrical connection terminals is arranged so that the so-called other electric current flow path successively passes through at least two of the photovoltaic junctions other than the first dissociated junction, which are then called at least two associated junctions. Thus, these associated junctions are electrically combined with each other in a series connection mode.

[0020] For such a configuration with two pairs of electrical connection terminals, the module may comprise two separate substrates: a first substrate which supports the first dissociated junction and the first pair of electrical connection terminals, and a second substrate which together supports the at least two associated junctions and the other pair of electrical connection terminals.

[0021] According to an improvement of the invention for a configuration with two pairs of electrical connection terminals, the first dissociated junction can be divided into a plurality of first cells which are electrically connected in series to form at least one first branch. Furthermore, the two associated junctions can also be divided into a plurality of second cells which are electrically connected in series to form at least one second branch which is separate from each first branch, but each second cell then comprising respective cells of the two associated junctions, which are electrically combined with each other according to the series connection mode inside this second cell. As previously, each of the first and second branches connects two electrical connection nodes of the module, so that all the branches are electrically connected in parallel inside the module.Furthermore, respective numbers of the first or second cells in each first or second branch are such that a result of multiplying for each first branch the number of first cells in this first branch by a maximum power operating voltage value relating to the first dissociated junction is substantially equal to a result of multiplying for each second branch the number of second cells in this second branch by a maximum power operating voltage value relating to the series connection of the two associated junctions.

[0022] Possibly, the cells within each junctional branch, lateral or medial, can be grouped into subsets, with the cells within each subset connected in series, and subsets within the same branch also connected in series.

[0023] Possibly also, the cells of each junction, lateral or median, can be grouped into several branches for this junction, all these branches being electrically connected in parallel in the module.

[0024] Possibly still, the cells of each junction branch, lateral or medial, can be electrically connected to each other according to any hybrid combination of the series connection mode and the parallel connection mode.

[0025] Generally speaking for the invention, the photovoltaic junctions of the module can advantageously be of the following types: the middle junction can be of a silicon-based type and have a forbidden band width which is between 1.0 eV (electron-volt, 1 eV = 1.6 10' 19joule) and 1.2 eV, and each of the first and second lateral junctions may be of a perovskite-based type and have a band gap that is between 1.3 eV and 1.9 eV.

[0026] Finally, a second aspect of the invention relates to a method for producing electricity which comprises arranging at a location on Earth at least one photovoltaic module which is in accordance with the first aspect of the invention, such that the faces of this module each form an angle which is between 24° and 40° relative to a direction which is horizontal at this location on Earth. Such an inclination of the photovoltaic module makes it possible to benefit from its bifacial structure to produce a greater quantity of electricity. Brief description of the figures

[0027] The characteristics and advantages of the present invention will appear more clearly in the detailed description below of non-limiting exemplary embodiments, with reference to the appended figures among which:

[0028] [Fig. 1] is a sectional view of a photovoltaic module which is in accordance with the invention, and which has a configuration with three pairs of electrical connection terminals;

[0029] [Fig. 2] illustrates a division of junctions of the photovoltaic module of [Fig. 1] into cells, as well as electrical connections which connect the cells;

[0030] [Fig. 3] is a plan view of a silicon-based junction such as may be used in the photovoltaic module of [Fig. 1];

[0031] [Fig. 4a] is a plan view of a perovskite-based junction such as may be combined with the junction of [Fig. 3] in the photovoltaic module of [Fig. 1];

[0032] [Fig. 4b] is a plan view of another perovskite-based junction such as may be combined with the junctions of [Fig. 3] and [Fig. 4a] in the photovoltaic module of [Fig. 1];

[0033] [Fig. 5a] is an exploded perspective view of an assembly of the junctions of the photovoltaic module of [Fig. 1];

[0034] [Fig. 5b] is a perspective view of the photovoltaic module of [Fig. 1], after assembly;

[0035] [Fig. 6] corresponds to [Fig. 1] for another photovoltaic module which is also in accordance with the invention, but which has a configuration with two pairs of electrical connection terminals;

[0036] [Fig. 7] corresponds to [Fig. 2] for the other photovoltaic module of [Fig. 6]; and

[0037] [Fig. 8] illustrates installation conditions for a photovoltaic module which conforms to the invention. Detailed description of the invention

[0038] For the sake of clarity, the dimensions of the elements shown in these figures do not correspond to actual dimensions or to actual dimensional ratios. In addition, some of these elements are represented only symbolically, and identical references indicated in different figures designate identical elements or those having identical functions.

[0039] The embodiments of the invention that are described below all correspond to a sequence of photovoltaic junctions of the following type: first perovskite-based lateral junction, silicon-based middle junction, and second perovskite-based lateral junction. The bandgap value for a silicon-based junction is of the order of 1.12 eV, and that for a perovskite-based junction is of the order of 1.6 eV. These two types of photovoltaic junctions are well known to those skilled in the art, and reference may be made to one of the many available publications that describe them, in particular the article entitled “Multi-junction solar cells paving the way for super high-efficiency”, by M. Yamaguchi et al., Journal of Applied Physics, 129, 240901 (2021). However, each perovskite-based junction may be replaced by a junction of another type whose bandgap is greater than that of the middle junction. For example, each perovskite-based junction may be replaced by a type III / V junction, such as GalnP (gallium-indium-phosphorus), or by an organic photovoltaic system, or by a dye-sensitized photovoltaic cell. The silicon-based junction, which constitutes the middle junction, may be of any design, including the models designated by the acronyms IBC for "Interdigitated Back Contact", PERC for "Passivated Emitter and Rear Cell", TOPCON for "Tunnel Oxide Passivated Contact" or HJT for "HeteroJunction Technology". It may also be replaced for this use by a junction of another type whose bandgap is less than that of each side junction.For example, the middle junction can alternatively be of the CdTe (cadmium telluride) or CIGS (copper indium gallium selenide) type.

[0040] The three junctions are arranged parallel inside a photovoltaic module, and parallel to the faces of this module. The middle junction is located between the first and second lateral junctions, independently of positions of transparent substrates which can be used to support these junctions and be located at any levels relative to the sequence of junctions. The two opposite faces of the photovoltaic module are likewise transparent, so that solar radiation, reflected radiation and / or diffuse radiation penetrates into the panel through these faces and then is incident on the junctions. By convention, the front face of the module, called the first face, is intended to be oriented mainly towards the Sun during use of the module to produce electricity, so that it receives direct solar radiation and diffuse daytime radiation.The rear face of the module, called the second face, is intended to be oriented primarily away from the Sun during module use, so that it receives diffuse daytime radiation and radiation that is reflected by the ground in accordance with its ground surface albedo value.

[0041] According to [Fig. 1], the photovoltaic module which is designated by the reference 100 and which is in accordance with the invention, may comprise: - a first transparent substrate 10, for example made of glass, which supports a first lateral photovoltaic junction 1 of perovskite type. The junction 1 may comprise, from the substrate 10: a first transparent conductive electrode electrically 1 1 , for example based on fluorine-doped tin oxide (SnO2:F) or tin-doped indium oxide (ITO), an electronic transport layer 12, denoted ETL, an active layer 13 based on perovskite, denoted PKT, a hole transport layer 14, denoted HTL, and a second electrically conductive transparent electrode 15, for example based on tin-doped indium oxide; - a silicon-based substrate which supports or incorporates a silicon-type photovoltaic junction 3, denoted Si, for example of the IBC, PERC, TOPCON or HJT type; and - a second transparent substrate 20, for example made of glass, which supports a second lateral photovoltaic junction 2 of perovskite type. The junction 2 may comprise, from the substrate 20: another first electrically conductive transparent electrode 21, for example based on fluorine-doped tin oxide or tin-doped indium oxide, another electronic transport layer 22, denoted ETL, another active layer 23 based on perovskite, denoted PKT, another hole transport layer 24, denoted HTL, and another second electrically conductive transparent electrode 25, for example based on tin-doped indium oxide.

[0042] Advantageously, the sequence of materials with their thicknesses which constitutes the junction 2 can be identical to that of the junction 1, just as the substrates 10 and 20 can be identical. The junction 3 is intermediate between the junctions 1 and 2, and constitutes the middle junction. The substrates 10 and 20 are preferably close to that of the junction 3, on each side of the latter and with each of the junctions 1 and 2 which is turned towards the substrate of the junction 3. An encapsulation sheet 40 is interposed between the junctions 1 and 3, and another encapsulation sheet 50 is interposed between the junctions 2 and 3. The encapsulation sheets 40 and 50 can be identical, made of a transparent and electrically insulating material such as polyolefin, for example.For such a constitution of the module 100, the substrate 10 may constitute its front face, denoted F1 and intended to be turned towards the Sun when the module 100 is used to produce electricity. The substrate 20 then constitutes the rear face of the module 100, denoted F2 and intended to be turned away from the Sun, towards the ground. In [Fig. 1], R1 generally designates the radiation which reaches the front face F1 of the module 100, and R2 generally designates the radiation which reaches its rear face F2.

[0043] Junction 1, based on perovskite, is provided with two electrical connection terminals: terminal B1 which is in electrical contact with electrode 11, and terminal B1' which is in electrical contact with electrode 15. Similarly, junction 2, also based on perovskite, is provided with two other electrical connection terminals: terminal B2 which is in electrical contact with electrode 21, and terminal B2' which is in electrical contact with electrode 25. Finally, junction 3, based on silicon, also has two electrical connection terminals: B3 which is positive and B3' which is negative. When using the panel 100 to produce electric current, terminals B1, B2 and B3 are output terminals of electric current from junctions 1, 2 and 3, respectively, and terminals B1', B2' and B3' are return terminals of electric current to the respective junctions.Each of the photovoltaic junctions 1, 2 and 3 thus has a pair of dedicated terminals, resulting in a total of three pairs of electrical connection terminals. To connect the module 100 to an external electrical circuit, it is necessary to connect the terminals B1, B2 and B3 together on the one hand, and B1', B2' and B3' on the other. In other words, the three junctions 1, 2 and 3 are to be electrically connected together according to a parallel connection mode between nodes N and N', as symbolically represented in [Fig. 1]. Thus, each junction can produce an individual electric current, without this individual current passing through any of the other two junctions. In the sense defined in the general part of this description, each of the three junctions 1, 2 and 3 is dissociated with respect to each of the other two.It is therefore not necessary to adapt the junctions relative to each other with respect to their respective capacity to conduct an external electric current. A simplification of the entire module 100 results, as well as the elimination of a limitation of the electrical power supplied.

[0044] However, such a module 100 with a parallel electrical connection mode for the junctions 1, 2 and 3 has an optimal operation when the electrical voltages which exist at the terminals of these junctions, taken separately from each other, are substantially equal. For this, according to an improvement of the invention, each junction 1, 2 or 3 can be divided into a plurality of cells which are electrically connected in series inside each junction, so as to constitute a respective branch of the parallel connection mode. Thus, the perovskite-based junction 1 is cut into NPKTI identical cells which are connected in series, on the substrate 10. Similarly, the junction 2 also based on perovskite is cut into NPKT2 identical cells which are connected in series, on the substrate 20. Those skilled in the art know how to make such junction cuts into cells which are carried by the same substrate and electrically connected in series, for example by means of etching patterns and conductive connections commonly designated by P1, P2 and P3. The junction 3 can be in the form of Nsi identical cells which are connected in series, for example by using a silicon-based photovoltaic module which is already commercially available.The voltage matching condition to be satisfied to obtain optimal operation of the module 100 is then: NPKTI VPKTI = NPKT2-VPKT2 = Nsi Vsi, where VPKTI, VPKT2 and Vsi denote respective output electrical voltage values ​​of a junction cell 1, a junction cell 2 and a junction cell 3, respectively. [Fig. 2] schematically shows the electrical configuration that results from such cutouts and connection modes for the module 100. Ci denotes each cell of junction 1, C2 each cell of junction 2, and C3 each cell of junction 3. Possibly, each of the junctions 1 and 2 may further have an additional cutout (not shown in [Fig. 2]), for example as commonly designated by etching pattern P4, so that this junction is made up of several identical branches that are electrically connected in parallel.

[0045] It is then possible to optimize the module 100 to a further extent to obtain maximum electricity production. For this, each cell output voltage value VPKTI, VPKT2 and Vsi can be taken equal to the operating voltage value at maximum power for this cell, i.e. equal to Vm PP _PKTi , Vmpp_PKT2 and Vmpp_si respectively, the abbreviation mpp meaning maximum power point.

[0046] Furthermore, so that the junctions 1, 2 and 3 can be easily superimposed within the same peripheral mechanical holding frame, and in a way that is optimized for the quantity of electricity produced per unit area of ​​the module 100, an individual cell size can be adopted for all the cells of the same junction, such that all the junction branches have peripheral dimensions that coincide.

[0047] For example, lighting conditions that are intended for module 100 may be as follows: - average power of the radiation R1 which is incident on the front face F1 of the module 100: 1000 W / m 2 (watt per square meter), including direct solar radiation and daytime diffuse radiation; and - average power of the radiation R2 which is incident on the rear face F2 of the module 100: 80 W / m 2 (watt per square meter), including daytime diffuse radiation and radiation that is reflected by the ground behind the module 100. These lighting conditions are achieved in particular when the module 100 is installed in the Marseille region in France, with an inclination of 32° (degree) relative to the ground surface, being oriented in azimuth towards the south, inside a row of solar panels which is typically at least 7 m (meter) apart from another parallel row, and for a soil type whose surface has an average albedo value which is between 0.2 and 0.8. Such installation parameters are illustrated by [Fig. 8]. In this figure, S denotes the Sun, and T the surface of the Earth's ground. Under the lighting conditions which have just been specified, the value Vm PP _si of maximum power operating voltage of a 3-junction C3 cell, based on silicon, is 0.62 V. For comparison, the open circuit voltage value of such a silicon-based photovoltaic cell Voc si is 0.71 V.

[0048] With a branch consisting of Nsi = 72 junction 3 cells that are electrically connected in series, the operating voltage at maximum power that exists between the two electrical connection terminals B3 and B3' of this branch of silicon-based cells is Nsi Vm PP_si = 72 0.62 = 44.64 V. A commercially available silicon-based photovoltaic module with such an electrical configuration is shown in [Fig. 3]. It has a rectangular shape, with a length Lsi equal to 1866 mm (millimeter), and a width Isi equal to 941 mm. In this figure, each silicon-based junction cell C3 comprises a respective 156 mm x 156 mm substrate that is separate from that of each other C3 cell, and reference numeral 31 designates electrical connection segments that constitute the series combination of the 72 C3 cells within the module. The C3 cells are arranged in six rows of twelve cells each in the junction module 3 shown, and the electrical connections 31 form a three-way meander parallel to the length direction Lsi. This silicon-based junction module 3, in its entirety, constitutes a branch of the parallel electrical combination which was described above in connection with [Fig. 2].

[0049] For the average radiation power value of 1000 W / m 2 on the F1 side of the module 100, a cell Ci of the junction 1 based on perovskite has the operating voltage value at maximum power Vm PP _PKTi = 0.92 V, while its open circuit voltage value VOC_PKTI is 1.10 V. The branch of NPKTI such cells Ci which are connected in series therefore has the following value of electrical voltage between its terminals B1 and B1 ': NPKTI -Vm PP _PKTi. To satisfy the voltage matching condition with each junction branch 3 as shown in [Fig. 3], the number NPKTI can be equal to Nsi VmPP _si / Vm PP _PKTi = 44.64 / 0.92 ~ 48.

[0050] Similarly for junction 2, and for the average radiation power value of 80 W / m 2 on the face F2 of the module 100, a cell C2 of the junction 2 based on perovskite has the operating voltage value at maximum power Vm PP _PKT2 = 0.85 V, while its open circuit voltage value VOC_PKT2 is 1.02 V. A branch of NPKT2 such cells C2 which are connected in series therefore has the following value of electrical voltage between its terminals B2 and B2': NpKT2-Vm PP _PKT2. To satisfy the voltage matching condition with each junction branch 3, the number NPKT2 is preferably equal to NsrVm PP _si / Vm PP _PKT2 = 44.64 / 0.85 « 52.

[0051] The output voltage value of the module 100 in electricity production operation, as existing between the nodes N and N', is then substantially equal to that of the junction module 3 of [Fig. 3], i.e. approximately 44.6 V. But the output current of the module 100 is the sum of the individual currents which are produced by the three junctions 1-3 for their respective operations at maximum power.

[0052] Each of the substrates 10 and 20 can advantageously be rectangular with length and width dimensions which are substantially identical to those Lsi and lsi of the junction module 3. According to a configuration which is proposed by the inventors, the perovskite-based junction 1 can be divided on the substrate 10, in its width equal to lsi, into four subsets each of NPKTI bands, forming in all 4- NPKTI bands which can all have identical individual widths, and all have the length Lsi. These subsets are designated by 11, 12, 13 and 14, respectively in [Fig. 4a], and a different cell Ci is individually constituted by each junction strip 1. All the cells Ci of the same of the subsets 1 i, 12, 13 and are electrically connected in series within this subset, and the subsets 11, 12, 13 and are electrically connected in parallel between the terminals B1 and BT, so as to constitute separate branches in the connection mode described above. For example, the cells Ci can be connected in series inside each of the subassemblies 11, 12, 13 and 14 by etching patterns and conductive connections P1, P2 and P3 as already mentioned above, and the subassemblies 11, 12, 13 and 14 can be separated by electrical insulation etchings of type P5.Thus, each strip which constitutes a cell Ci on the substrate 10 can have a length equal to Lsi and a width IPKTI equal to lsi / (4 NpKTi) = 4.9 mm, or rather 4.82 mm by removing the thickness of the conductive connections and that of the electrical insulation etchings between adjacent sub-assemblies.

[0053] In the same way, the junction 2 also based on perovskite can be divided on the substrate 20, in its width equal to lsi, into four subsets each of N KT2 bands, forming in all 4 NPKT2 bands which can all have identical individual widths, and all have the length Lsi. These subsets are designated by 2i, 22, 23 and 24, respectively in [Fig. 4b], and each junction band 2 individually constitutes a cell C2. All the cells C2 of the same of the subsets 2i, 22, 23 and 24 are electrically connected in series within this subset, and the subsets 2i, 22, 23 and 24 are electrically connected in parallel between the terminals B2 and B2', so as to constitute as many separate branches. The C2 cells can also be connected in series within each of the subassemblies 2i, 22, 23 and 24 by etching patterns and conductive connections P1, P2 and P3.Thus, each strip which constitutes a cell C2 on the substrate 20 can have a length equal to Lsi and a width I KT2 equal to lsi / (4 NpKT2) « 4.5 mm, or rather 4.42 mm by further removing the thickness of the conductive connections and that of the electrical insulation etchings between adjacent sub-assemblies. With reference to the series connection mode of the cells Ci for junction 1, and of the cells C2 for junction 2, the dimension lsi / 4 has been called. branch length of junctions 1 and 2 in the general part of this description. The length of junction 3 as appearing in [Fig. 3] is Lsi.

[0054] Possibly, additional cutouts by P4 insulation etches may be added in each perovskite-based junction 1, 2, to divide each junction branch into several branches which are electrically connected in parallel on each substrate 10, 20, respectively.

[0055] Thanks to the cell dimensions which have been given above, the substrate 10 with the junction 1 as described with reference to [Fig. 4a], and that 20 with the junction 2 as described with reference to [Fig. 4b], can be assembled with the junction module 3 as described with reference to [Fig. 3], in accordance with [Fig. 1] inside a common peripheral mechanical holding frame. Inside this assembly, the electrical connections of parallel combination of all the branches can be made in one of the ways known to the person skilled in the art, using strips of electrically conductive paste or dedicated connector elements. [Fig. 5a] and [Fig. 5b] illustrate the assembly of the module 100 which is thus produced: a view of the junctions 1-3 superimposed to form the module 100 with the bifacial configuration ([Fig. 5a]), and the assembly of the bifacial module 100 in a peripheral mechanical holding frame 101 ([Fig. 5b]).

[0056] Another embodiment of the invention is now described, with two pairs of electrical connection terminals, i.e. four electrical connection terminals.

[0057] As shown in [Fig. 6], the perovskite-based junction 1 and the silicon-based junction 3 now together constitute a tandem assembly, being supported by the same substrate. This common substrate can be incorporated into the junction 3. Alternatively, the two junctions 1 and 3 can be made in the form of a stack of thin layers deposited on a transparent substrate. A recombination or tunnel junction layer 60, denoted INT, is intermediate between the hole transport layer 14 of the junction 1 and the junction 3, in order to achieve a series association of these two junctions 1 and 3. For this reason, the junctions 1 and 3 have been said to be associated in the general part of the description for this embodiment. Insulating encapsulation sheets 50 and 70 are arranged on each side of the tandem assembly. junctions 1 and 3, with a protective glass plate 80 over the sheet 70 to constitute the front face F1 of the module 100.

[0058] The perovskite-based junction 2 which is carried by the glass substrate 20 may be identical to that which has been described with reference to [Fig. 1]. It also constitutes a junction which is dissociated from the junctions 1 and 3. The electrical connection terminal B2, which is in contact with the transparent conductive electrode 21, is electrically connected by the node N with an electrical connection terminal B13 which is in contact with the transparent conductive electrode 11. Furthermore, the electrical connection terminal B2' which is in contact with the transparent conductive electrode 25, is electrically connected by the node N' with an electrical connection terminal B13' which is in contact with a transparent conductive electrode 31 of the silicon-based junction 3. Thus, the node N forms the current output terminal of the module 100, and the node N' forms the current return terminal of this module.For this alternative embodiment, the module 100 may be intended to be oriented so that the tandem assembly of junctions 1 and 3 is on the Sun side, as opposed to junction 2, and with the perovskite-based junction 3 being closest to the front face F1 of the module.

[0059] The operating voltage value at maximum power Vm PP _si-PKTi of the tandem assembly of junctions 1 and 3 is about 1.68 V for the lighting conditions mentioned above, while its open-circuit voltage value Voc_si-PKTi is about 1.96 V. Then, by applying the optimization principles set out above to module 100 of [Fig. 6], the voltage matching of at least one branch of cells C13 of the tandem assembly of junctions 1 and 3 with at least one branch of cells C2 of junction 2 is preferably based on the operating voltage values ​​at maximum power V mpp _si-PKTi and V mpp_PKT2. In other words, the agreement relationship is now: Nsi-PKTi V mpp _si-PKTi = NpKT2-Vm PP _PKT2, where NSI-PKTI is the number of tandem assembly C13 cells of junctions 1 and 3 that are connected in series in the corresponding branch. [Fig. 7] schematically shows the electrical configuration that is thus obtained for the module 100 of [Fig. 6]. For example, NSI-PKTI can be taken equal to 72 cells and NPKT2 equal to 142 cells, resulting in an operating output voltage value for the module 100 of approximately 121 V.

[0060] Again, to allow easy and optimal assembly in relation to the quantity of electricity produced per unit area of ​​the module 100, respective sizes of the tandem assembly cells C13 of junctions 1 and 3 and those C2 of junction 2 can be chosen so that the branches of cells connected in series have superimposable dimensions within the same peripheral mechanical holding frame.

[0061] It is understood that the invention may be reproduced by modifying secondary aspects of the embodiments which have been described in detail above, while retaining at least some of the advantages cited. In particular, the following modifications may be implemented: - the invention can be applied to any number of photovoltaic junctions which are assembled in the same module to absorb radiation efficiently in complementary spectral intervals. In particular, five photovoltaic junctions can be superimposed, with band gap values ​​that are all the greater the closer the junction is to one of the faces of the module; - each photovoltaic junction is divided into cells which can be connected together in any combination of series and parallel connections, in order to obtain voltage matching of all the photovoltaic junctions of the module; and - the types of photovoltaic junctions that are assembled together in the module, including the materials of the junctions, can be changed to others.

[0062] Finally, all numerical values ​​cited are for illustration purposes only and may be changed depending on the implementation method considered.

Claims

Claims

1. Bifacial photovoltaic module (100), arranged to produce electricity from a first radiation (R1) which is incident on a first face (F1) of the module and simultaneously from a second radiation (R2) which is incident on a second face (F2) of the module, parallel and opposite to the first face, during use of the module, the module (100) comprising at least three photovoltaic junctions which each extend parallel to the first (F1) and second (F2) faces and are successively offset along a direction of passage of the module between said first and second faces, the three junctions comprising a middle junction (3), a first lateral junction (1) located between the first face and the middle junction, and a second lateral junction (2) located between the middle junction and the second face,wherein a band gap of the first lateral junction and a band gap of the second lateral junction are each greater than a band gap of the middle junction, the module (100) further comprising a first pair of electrical connection terminals (B2, B2') arranged to conduct an electric current produced by one of the photovoltaic junctions (1-3), called the first dissociated junction (2), according to a first electric current flow path which is separated from at least two other (1, 3) of the junctions, and further comprising at least one other pair of electrical connection terminals (B1, B1', B3, B3'; B13, B13') arranged to conduct another electric current produced by at least one of the photovoltaic junctions (1-3) other than said first dissociated junction, according to another electric current flow path which is separated from the first dissociated junction (2),characterized in that respective numbers of cells in branches of the first (1) and second (2) lateral junctions are different.,

2. The module (100) of claim 1, wherein maximum power operating voltage values ​​used to determine the respective numbers of cells in the branches of the first (1) and second (2) side junctions correspond to average power values ​​of the first (R1) and second (R2) radiations which are different.

3. Module (100) according to claim 1 or 2, comprising in addition to the first pair of electrical connection terminals (B2, B2'), a second (B1, B1') and a third (B3, B3') pair of electrical connection terminals, the second pair of electrical connection terminals (B1, B1') being arranged to conduct a second electric current produced by a second of the photovoltaic junctions, called the second dissociated junction (1) and distinct from the first dissociated junction (2), in accordance with a second electric current flow path which is separated from the first electric current flow path, and the third pair of electrical connection terminals (B3, B3') being arranged to conduct a third electric current produced by a third of the photovoltaic junctions, called the third dissociated junction (3) and distinct from each of the first (2) and second (1) dissociated junctions,according to a third electric current flow path which is separate from the first and second electric current flow paths.,

4. Module (100) according to claim 3, comprising first (20), second (10) and third separate substrates, the first substrate supporting the first dissociated junction (2) and the first pair of electrical connection terminals (B2, B2'), the second substrate supporting the second dissociated junction (1) and the second pair of electrical connection terminals (B1, B1'), and the third substrate supporting the third dissociated junction (3) and the third pair of electrical connection terminals (B3, B3').

5. A module (100) according to claim 3 or 4, wherein each of the junctions among the middle junction (3), the first lateral junction (2) and the second lateral junction (3) is cut into a plurality of cells (Ci, C2, C3) which are electrically connected in series to form at least one respective branch which is separate from each branch of each other junction, and which extends between the two electrical connection terminals (B1, B1', B2, B2', B3, B3') of the corresponding junction, and the module further comprises two electrical connection nodes (N, N') each connected to one of the electrical connection terminals of each junction, so that all the branches are electrically connected in parallel within the module, and in which numbers of cells in each branch are such that a result of multiplying for each branch the number of cells by a value of operating voltage at maximum power relative to the junction of said branch, is substantially equal for all branches.

6. Module (100) according to claim 5, wherein the respective values ​​of operating voltage at maximum power which are relative to the first (1) and second (2) lateral junctions, are different, so the respective numbers of cells in the branches of said first and second lateral junctions are also different, and wherein dimensions of the cells (Ci, C2) of the first and second lateral junctions are such that respective branch lengths of said first and second lateral junctions are equal to a length of the middle junction (3), or are divisors of a length of the middle junction.

7. Module (100) according to claim 1 or 2, wherein said other pair of electrical connection terminals (B13, B13') is arranged so that said other electric current flow path successively passes through at least two of the photovoltaic junctions other than said first dissociated junction (2), called at least two associated junctions (1, 3), so that said at least two associated junctions are electrically combined with each other in a series connection mode.

8. Module (100) according to claim 7, comprising two separate substrates, a first (20) of said substrates supporting the first dissociated junction (2) and the first pair of electrical connection terminals (B2, B2'), and another of said substrates supporting together the at least two associated junctions (1, 3) and said other pair of electrical connection terminals (B13, B13').

9. Module (100) according to claim 7 or 8, wherein the first dissociated junction (2) is cut into a plurality of first cells (C2) which are electrically connected in series to form at least one first branch, and the two associated junctions (1, 3) are cut into a plurality of second cells (C13) which are electrically connected in series to form at least one second branch which is separated from each first branch, each second cell comprising a respective cell of each of the two associated junctions which are electrically combined with each other according to the series connection mode inside said second cell, each of the first and second branches connecting two electrical connection nodes (N, N') of the module, so that all the branches are electrically connected in parallel inside the module, and in which respective numbers of the first or second cells in each first or second branch are such that a result of multiplying for each first branch the number of first cells in said first branch by a maximum power operating voltage value relating to the first dissociated junction,is substantially equal to a result of multiplying for each second branch the number of second cells in said second branch by a maximum power operating voltage value relating to the series connection of the two associated junctions.,

10. A module (100) according to any preceding claim, wherein the middle junction (3) is of a silicon-based type and has a band gap of between 1.0 eV and 1.2 eV, and each of the first (1) and second (2) side junctions is of a perovskite-based type and has a band gap of between 1.3 eV and 1.9 eV.

11. A method of producing electricity comprising arranging at a location on Earth at least one photovoltaic module (100) which is in accordance with any one of the preceding claims, such that the faces (F1, F2) of said module each form an angle which is between 24° and 40° relative to a direction which is horizontal to said location on Earth.

12. A method according to claim 11, wherein the respective numbers of cells in the branches of the first (1) and second (2) lateral junctions are different to obtain respective total electrical voltages of all branches which are substantially equal with maximum power operating voltage values ​​for each of said first and second lateral junctions which correspond to average values ​​of incident radiation power on the two faces (F1, F2) of the module which are different.

13. A method according to claim 12, wherein the maximum power operating voltage values ​​used to determine the respective numbers of cells in the branches of the first (1) and second (2) lateral junctions correspond to average power values ​​of the first (R1) and second (R2) radiations which are different depending on which of the first (F1) and second (F2) faces of the module (100) is facing the Sun, and depending on an albedo value of a ground towards which the other face of said module is facing.

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