Photovoltaic cell set and battery module with electronic circuit having a measurement area

Abstract

To provide a photovoltaic cell set and a battery module having an electronic circuit with a measurement region.SOLUTION: The present invention relates to a photovoltaic cell (2, 12) set (10). The set (10) has at least one conductive layer (21, 23, 25, 25') in the upper surface of the substrates (22, 28) or the bottom surface of the substrates (22, 28) to establish an electric connection of the photovoltaic cell (2, 12). At least one larger first photovoltaic cell (2) is provided to capture light energy to be converted to electric energy in a module (1). At least one smaller second photovoltaic cell (12) dependent from the first photovoltaic cell (2) is provided. The second photovoltaic cell (12) is formed to measure a voltage or a current in the module (1) to optimize the operations of the module (1).SELECTED DRAWING: Figure 4A

Description

[Technical Field]

[0001] The present invention relates to a photovoltaic cell set, and also to a photovoltaic cell set with an electronic circuit, having at least one region for measuring at least one voltage or one current. [Background technology]

[0002] Converters responsible for harvesting the energy of photovoltaic cells are well known. Preferably, they should integrate a maximum power point tracking mechanism, defined by the term MPPT ("maximum power point tracking"). This maximum power Pmpp corresponds to an operating point MPP, which is characterized by a very specific voltage Vmpp and current Impp that also depend on the illumination level.

[0003] Various techniques are known, and in particular the so-called "perturb and observe" method can be mentioned, which consists in periodically varying the operating voltage and observing the resulting power fluctuations, as described in WO 2013 / 105008. Depending on the appearance of these fluctuations, the power fluctuations are either maintained or, conversely, reversed. Generally, this method is very effective, but it can still have some drawbacks. In particular, the drawbacks are the risk of wobble and the relatively complex electronics. This can significantly affect the electrical consumption of the regulating system in low-power systems and watchmaking applications.

[0004] Another well-known method is the so-called "open circuit voltage" method, which can be seen in FIG. 1 of a photovoltaic cell 2 module 1 with an electronic circuit 3. This method consists in periodically measuring the open circuit voltage Voc ("open circuit") of the solar cell 2 and, accordingly, adapting the operating voltage to a value that is as close to Vmpp as possible. A simple variant consists in multiplying the open circuit voltage by a constant, for example, 80%, and then adjusting the operating voltage accordingly. This method is easy to implement in the electronic circuit, but is not ideal under all lighting conditions, since the Vmpp / Voc ratio is not perfectly constant depending on the lighting. A more complex variant consists in adapting a coefficient depending on the open circuit voltage. The voltage function Vmpp=f(Voc) should be determined in advance so that it can be estimated later by electronic adjustment, for example, using a look-up table.

[0005] The drawback of the "open-circuit voltage" method is that energy collection is interrupted for a short time while the open-circuit voltage Voc is measured. In practice, the duration of this measurement depends on the time required for the solar cell to charge the inevitable electrical capacitor at its terminals relative to Voc, whether this capacitor is internal or external, which the solar cell has at its terminals. Furthermore, the Voc measurement period must be adapted to variations in lighting. For applications in the watchmaking industry, consider the example of a solar watch wearer moving through a forest. With each step and arm movement, the light received varies significantly, and the operating voltage should ideally be adapted instantly or frequently, for example, every second. In practice, interrupting energy collection so frequently to measure the voltage Voc is wasteful.

[0006] Figure 1 shows a prior art solar cell 2 module 1 with electronic circuitry 3, using the open circuit voltage measurement method partially described above. The prior art solar cell 2 module 1 comprises electronic circuitry 3, which has components connected outside of the electronic circuitry 3. The solar cell or photovoltaic cell 2 may be in the form of a watch face or bezel or crystal, or another part of the watch.

[0007] On one side of the module 1, a solar cell 2 is intended to capture light and convert this light into electrical energy, such as a voltage applied on a first capacitor C1. The voltage VPV applied on the capacitor C1 is supplied to a switching controller 5 in the electronic circuit 3. An inductor L1 is also provided in association with the first capacitor C1 and the input Vin of the switching controller 5, which is known as a "step-up" type DC-DC converter circuit.

[0008] The timing of the switching is performed in the switching controller 5, which at a predetermined time closes the switch 6 arranged between the first capacitor C1 and the second capacitor C2 and measures the open-circuit voltage Voc. This open-circuit voltage Voc is supplied to the adapter 4, which then adapts the voltage transmitted to the switching controller 5 to, for example, a value corresponding to 80% of the average maximum value obtained from the adapter 4, thereby adapting the operating voltage accordingly to a desired value around Vmpp. The desired operating voltage is thus provided at the output Vsup and applied to the output capacitor Cs. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2013 / 105008 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention therefore proposes a photovoltaic cell set intended to be part of a photovoltaic module accompanied by an electronic circuit, which allows frequent, even permanent, measurement of the voltage of the photovoltaic cell or the current of this photovoltaic cell, which allows for rapid adaptation of the operating point of the electronic circuit and of the entire module, overcoming the drawbacks of the prior art mentioned above. The present invention facilitates voltage measurement even at high frequency, making it possible to overcome the drawbacks of the prior art mentioned above.

[0011] This advantage is even greater when lighting conditions change rapidly and frequently, as is typically the case when the watch is worn by an active user. The combination of a portion or area of ​​the photovoltaic cell set that measures voltage, e.g., open-circuit voltage, and a portion or area that captures light energy allows voltage measurements to be performed at all times, regardless of the operating frequency of the electronic circuitry of the accompanying photovoltaic module. [Means for solving the problem]

[0012] To this end, the invention relates to a photovoltaic cell set as defined in independent claim 1.

[0013] Particular embodiments of the photovoltaic cell set are defined in dependent claims 2 to 20.

[0014] For this purpose, the invention also relates to a photovoltaic module with an electronic circuit, which has a region for measuring voltage or current, according to independent claim 21 .

[0015] Particular embodiments of the module are defined in dependent claims 22 and 23.

[0016] The advantage of the photovoltaic cell set for said photovoltaic module with electronic circuitry is that, according to a first variant, the photovoltaic cell set comprises a first or a plurality of first large-sized photovoltaic or solar cell(s) intended to capture light energy and convert it into electrical energy, and an independent second small-sized photovoltaic or solar cell intended to measure the voltage or current in the electronic circuitry of the module. An advantage may be, for example, to measure, continuously, the open-circuit voltage or the short-circuit current.

[0017] The first photovoltaic cell(s) may consist of thin film cell(s).

[0018] Advantageously, the part or area intended for measuring the voltage or current and capturing the light energy may occupy a surface area corresponding to, for example, 1% of the total surface area of ​​all the photovoltaic cells. Conversely, the operation of continuously measuring this voltage, for example the open circuit voltage or this short circuit current, for example within the electronic circuitry of the module, in fact makes it possible to capture at least 10% more electrical energy, a significant advantage compared to the prior art.

[0019] The first photovoltaic cell of the set is a large-sized photovoltaic cell that captures light energy. The second photovoltaic cell of the set is a small-sized photovoltaic cell that is primarily intended to function to measure voltage or current, such as open-circuit voltage V or short-circuit current, within the electronic circuit of the module. Naturally, it is assumed that the two types of photovoltaic cells have similar open-circuit voltages V in response to illumination. In the watchmaking application of the present invention, the first solar cell(s) can be integrated into the watch face, directly conform to the shape of the watch face, or bonded to the watch crystal. Having two different types of cells can have cosmetic disadvantages because the edges of the cells are visible. Furthermore, physical separation of the two cells by an insulating area tends to reduce the effective surface available for energy collection. However, when a photovoltaic cell set intended for a photovoltaic module with electronic circuits is bonded to a watch face or crystal, the parts of the photovoltaic cell set that may be visible can be made the same color as the first cell and / or the second cell, so that the parts of the photovoltaic cell set cannot be distinguished through the watch crystal. Another minor drawback is that by providing an insulating area between the two parts, the surface of the first cell intended to capture the light energy to convert it into electrical energy is reduced to a minimum.

[0020] Another advantage of a photovoltaic cell set intended to be part of a photovoltaic module with an electronic circuit is that, according to a second variant, the photovoltaic cell set of said module has the properties, in particular, of an IBC type (initials for "interdigitated back contact") silicon cell. The concept basically consists in implementing a single-section cell for the monocrystalline substrate and the surface amorphous layer, isolating only the backside structure by diffusion and metallization. In other words, the concept consists in allocating a small area of ​​the IBC cell to measure the voltage, for example the open-circuit voltage Voc, by means of two electrically independent p- and n-pins or combs on the backside of the cell. This measurement area is assumed to be significantly smaller than the main area dedicated to energy collection.

[0021] The objects, advantages and features of a photovoltaic cell set intended to be part of a photovoltaic module with electronic circuitry, having at least one region for measuring voltage or current, will become better apparent in the following non-limiting description, which refers to the drawings. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a diagram of a prior art photovoltaic module, which is equipped with data processing electronics and adapted to measure open circuit voltage; FIG. [Figure 2] 1 is a diagram of a photovoltaic module according to the invention, comprising an electronic circuit for processing data; [Figure 3] 1 is a diagram of an embodiment of the various layers of a set of photovoltaic cells, the set of photovoltaic cells being intended to be part of a photovoltaic module with an electronic circuit of a first variant according to the invention; FIG. [Figure 4A] 1 shows a top view of a support in the form of a wafer of photovoltaic cell sets of a photovoltaic module with electronic circuitry according to a first variant of the invention; FIG. [Figure 4B] 1 is a cross-sectional view of a photovoltaic cell set in the form of a wafer for measuring voltages in the electronic circuits of the module, for example open circuit voltages, and for viewing different contacts for capturing electrical energy by optical signals, according to the present invention; [Figure 5A] 1 shows a top view of a support in the form of a wafer of photovoltaic cell sets of a photovoltaic module with electronic circuitry according to a second variant of the invention; FIG. [Figure 5B] 1 is a cross-sectional view of a photovoltaic cell set in the form of a wafer, for example, showing at least two teeth of each comb alternating across a silicon crystal layer, according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] In the following description, all the components of the photovoltaic cell set intended to be part of the photovoltaic module with electronic circuit will be described. All measurement basic components known in the art will be briefly described. The structure of the photovoltaic cell set for the photovoltaic module with electronic circuit and its design will be mainly described.

[0024] In a first variant, as will be explained below, particularly in FIG. 2, a set 10 of photovoltaic cells 2 and 12 can be placed on a support, such as a glass plate, which can form the glass of a watch worn primarily on the wrist. The two photovoltaic cells 2 and 12 convert light energy into electrical energy, allowing for the capture of light energy, while a smaller second cell 12 is used to measure voltage, e.g., open-circuit voltage, and possibly also current, e.g., short-circuit current. Laser machining can be performed through the glass, since it is both an insulator and transparent. In the case of a cell for measuring open-circuit voltage, the measured output power is equal to zero, thereby specifically specifying the open-circuit voltage.

[0025] FIG. 2 shows a photovoltaic cell 2, 12 module 1 with an electronic circuit 3. Several electronic components still connect the base of the electronic circuit 3 and the photovoltaic cell(s) 2, 12 of the present invention. The module 1 further comprises one or more photovoltaic or solar cell(s) 2, 12 connected to the electronic circuit 3, and different electronic components connecting the photovoltaic cell(s) and the base of the electronic circuit 3. For example, it is possible to consider having a first cell or several first photovoltaic cells 2 connected together to form a watch face or arranged on a support such as a watch glass, and at least one second photovoltaic cell 12 for measuring the open-circuit voltage, which is essentially a miniature photovoltaic or solar cell. This second solar cell is configured to be able to independently measure the open-circuit voltage Voc, but may also be configured to measure the short-circuit current in the module 1. This miniature photovoltaic cell may be permanently, in particular continuously, connected without being disconnected at the start of the open-circuit voltage measurement. Thanks to this miniature photovoltaic cell 12 it is therefore possible to provide one piece of information for adapting the operating point of the electronic circuit 3 or of the entire module 1 comprising the electronic circuit 3 .

[0026] As shown in FIG. 2, module 1 includes at least one first photovoltaic or solar cell 2 for capturing and converting light energy into electrical energy. The first photovoltaic or solar cell 2 is inserted on the positive side of input capacitor C1, which is also connected on the negative side to ground Vss. Module 1 also includes an inductor L1 connecting the positive side of input capacitor C1 to an input voltage terminal Vin of a switching controller 5 in electronic circuit 3, known as a "step-up" DC-DC converter circuit. The timing of this switching controller 5 can be adjusted by a local oscillator or base oscillator, partially constituted by the inductor L1 connected to LX1. However, a time base or time-adjusting oscillator can also be fully integrated into switching controller 5 or electronic circuit 3, specifically timing all operations of switching controller 5.

[0027] The electronic circuit 3 also includes an adapter 4, which is connected to a switching controller 5 and directly to the second photovoltaic or solar cell 12. Configuration parameters can be communicated between the switching controller 5 and the adapter 4, which relate to a determined voltage level, i.e., a target value Vmpp_cible, required for proper module operation. The adapter 4 constantly, particularly continuously, receives a measurement signal of the voltage or current of the second photovoltaic or solar cell 12, e.g., the open-circuit voltage Voc or the short-circuit current. At the start of the measurement, there is an increase in current through the diode of the second photovoltaic or solar cell 12 until a voltage point Vmpp is reached, which corresponds to the ideal operating voltage of the electronic circuit 3. However, the voltage-current curve ends with the current dropping off before reaching the open-circuit voltage value Voc on the voltage axis, where the current becomes zero. The operating voltage of the electronic circuit close to the target optimal value Vmpp can be determined by a voltage function Vmpp=f(Voc).

[0028] Thus, the second photovoltaic cell 12 may be provided to measure the voltage or current, for example the open circuit voltage Voc, at all times, in particular continuously, since this second photovoltaic cell or solar cell 12 is independent of the first photovoltaic cell or solar cell(s) 2 and is responsible for measuring the light energy by converting it into electrical energy.

[0029] This voltage, e.g., a measured value of the open-circuit voltage Voc, is supplied to the adapter 4, which adapts the voltage transmitted to the switching controller 5 to, e.g., a value corresponding to 80% of the average maximum value emitted by the adapter 4, thereby adapting the operating voltage accordingly to a desired value around Vmpp. Vmpp may have a predefined target value (Vmpp_cible). The desired operating voltage is therefore provided at the output Vsup of the switching controller 5 and is applied to the positive side of the output capacitor Cs, the negative side of which is connected to ground Vss.

[0030] It should be noted that the connections of the photovoltaic module 1 with the electronic circuitry 3 can be reversed to the positive voltage terminal rather than to the ground Vss as described in Figures 1 and 2 to explain the operation of the module 1.

[0031] To create a photovoltaic cell 2, 12 module 1 with a first variant of the electronic circuit 3, first refer to Figure 3, which shows the various layers of a photovoltaic cell set 10, intended to be part of a photovoltaic module 1 with a first variant of the electronic circuit of the set of layers of the module 1, before connecting the photovoltaic cells. The set 10 comprises a first conductive layer, which may be a first transparent conductive layer 21 intended to fasten a substrate 22 under the surface of the support of the set.

[0032] A first conductive layer 21 can be disposed on a first surface of a substrate 22, which is made of an amorphous material, for example, a semiconductor material such as amorphous silicon (a-Si). The first conductive layer 21 can be a transparent conductive oxide (TCO) layer, although other conductive layers can be considered. A second metal layer 23 can be disposed on a second surface of the substrate 22 or support opposite the first surface.

[0033] Therefore, the material of the substrate 22 of the first photovoltaic cell 2 may be amorphous silicon.

[0034] The second conductive layer 23 is connected to the first conductive layer 21 by a peripheral opening of the set 10 made in the substrate 22 or in the first photovoltaic cell 2 .

[0035] Of course, several other layers may be placed above or below the layers of the set described above.

[0036] The photovoltaic cell set 10 is intended to be fastened by its first conductive layer 21 onto the underside of a transparent support 20 such as glass, e.g. a watch glass, or onto another type of support. The total thickness of the set 10 may be less than 500 μm, more preferably less than 100 μm.

[0037] It should be noted that in this first variant, the transparent support 20 or another type of support may be part of the set 10 after all the connection steps of the electronic components and the photovoltaic cells of the module 1 .

[0038] A first variant of the photovoltaic cell set 10, which becomes part of a photovoltaic module with electronic circuitry, is shown in Figures 4A and 4B. Figure 4A shows a top view of the photovoltaic cell set 10, while Figure 4B shows a vertical view at the level of the connecting contacts of the photovoltaic cell set 10.

[0039] According to a first variant, the photovoltaic cell set 10 comprises two cells arranged independently of each other: a first photovoltaic cell 2 of large size is configured to collect light energy and convert it into electrical energy, while a second photovoltaic cell 12 of small size is configured to perform measurements of the open circuit voltage Voc and possibly the short circuit current.

[0040] The first photovoltaic cell 2 can be a thin film cell arranged on a substrate support of another type.

[0041] 4A and 4B, the substrate 22 is rather shown in the form of a wafer or wafer portion on which and where the electrical contacts of the photovoltaic cells are made. The photovoltaic or solar cells are made in one or more substrate wafer(s) primarily composed of silicon wafers, or on one or more support(s) of material made of glass, plastic or metal with an insulating layer, or on a crystalline layer.

[0042] FIG. 4A shows a top view of a first variant of a photovoltaic cell set 10 intended to be part of a photovoltaic module with an electronic circuit. In contrast, FIG. 4B shows a cross-sectional view at the level of the electrical contacts of an optical sensor set 10 fastened to a support 20, which is part of the set 10. The set 10, in which the first layer is fastened to the underside of the support 20, preferably made of glass, is particularly suitable for laser machining operations. Assuming that the glass and some parts of the set are transparent, such as the first transparent conductive oxide layer, machining or etching can be performed from the top surface of the glass through the module. This set 10 is, for example, a variant of a thin-film cell on a support made of glass.

[0043] In the case of known laser machining, said etching is carried out through the amorphous silicon substrate 22, giving access to the first transparent conductive oxide layer 21, which can be polarized to a common positive or negative potential, in this case preferably a positive potential. To achieve this polarization, a second metal layer 23 (defined by P2) on the opposite side of the substrate 22 can connect the first transparent conductive oxide layer 21, for example by means of a metal ring P2. A positive contact Cp1 arranged on this second metal layer 23 at the border or periphery allows the entire first transparent conductive oxide layer 21 to be polarized to the same potential, for example a positive potential, in both photovoltaic cells.

[0044] For example, it is possible to create an insulating layer P3 for the large photovoltaic cell and another insulating layer P13 for the small photovoltaic cell by laser machining. Each insulating layer P3 and P13 extends from the second metal layer 23 at least until it contacts the transparent conductive oxide layer 21. It is therefore possible to apply a negative contact Cn1 on the large first photovoltaic cell on the substrate through the second metal layer 23, which is insulated from the boundary P2. This also makes it possible to insulate the small photovoltaic cell by another insulating layer P13 and connect it by another negative contact Cn2 on the small second photovoltaic cell on the substrate through the second metal layer 23.

[0045] Naturally, for the cases described above, the common power pad corresponds to the positive terminal of the power supply, which mainly results from the conversion of light energy into electrical energy by the first photovoltaic or solar cell. However, in the case described in particular in Figure 2, the common pad is rather a ground terminal, which is defined as the negative terminal. However, the connection configuration of the different contact pads remains unchanged.

[0046] An insulation P3 of the large first photovoltaic or solar cell is provided, which in this case has a circular shape but is not limited to this shape shown in Fig. 4A. Furthermore, an interconnection line or strip P2 is provided around this insulation P3, connecting the common complementary contact Cp1 of the positive connections on the positive sides of the first and second photovoltaic or solar cells.

[0047] A positive contact Cp1 is placed on the second conductive layer 23 at the periphery and is intended to enable the first conductive layer 21 in both photovoltaic cells to be polarized to the same positive potential, a negative contact Cn1 is placed on the large photovoltaic cell 2 on the substrate via the second conductive layer 23 insulated from the boundary P2, and another negative contact Cn2 is placed on the small photovoltaic cell 12 on the substrate via the second conductive layer 23.

[0048] The second or small photovoltaic cell 12 is generally located within the first or large photovoltaic cell 2, although it is also possible to consider placing the small photovoltaic cell 12 outside the insulation P3 up to the boundary P2.

[0049] It should also be noted that in a photovoltaic cell set 10 assembled into a photovoltaic module with electronic circuitry, it is possible to consider reversing the polarity of the different contacts disposed on each photovoltaic cell. In this regard, after assembling the set 10 into a module 1, the complementary contact Cp1 becomes the negative side contact, while the first negative contact Cn1 and the other negative contact Cn2 can become the positive side contacts.

[0050] 5A and 5B show a second variant of the photovoltaic cell set 10, in which the entire electrical connection between the contacts is made on the back side of the photovoltaic cell set 10, via at least one conductive layer 25, 25', under the substrate 28. This second variant utilizes the properties of IBC type (acronym for "interdigitated back contact") silicon cells. In this embodiment, the underlying concept is to implement an essentially single-section cell for a monocrystalline substrate (wafer), dividing or isolating only the back structure of the wafer, for example by diffusion and metallization. In other words, this consists in allocating a small area of ​​the IBC cell for the measurement of the open-circuit voltage Voc or the short-circuit current, by means of at least two electrically independent pins or combs under the substrate 28.

[0051] As can be seen from FIG. 5B, the photovoltaic cell set 10 is composed of at least one passivation layer 27, which is disposed directly on the substrate 28 from top to bottom. The at least one passivation layer 27 may be composed of crystalline silicon. However, a silicon nitride (SiN) layer 26 or a silicon oxide (SiO2) layer, which serves as an anti-reflection layer, may also be added on the passivation layer 27. Furthermore, at least one p-type region and one n-type region, preferably several p-type and n-type regions, may be fabricated on the opposite side of the substrate 28. These regions are alternately arranged parallel to each other, spaced apart from each other, and may be straight or curved, for example, in the form of a circular arc or another suitable shape. These regions are then covered with a conductive layer, which is then configured to define a first comb 25 and a second comb 25′. The teeth of the first comb 25 are arranged on the p-type region, while the teeth of the second comb are arranged on the n-type region.

[0052] It should be noted that a support or support element, which may be made of transparent glass, may be assembled or fastened onto the anti-reflection layer 26 so as to protect it from wear over time. Furthermore, it may be considered to place a protective layer on the combs 25, 25', also to protect them from wear.

[0053] It should be noted that the n- and p-regions can be made by diffusion or deposition of layers of the respective type (eg, amorphous Si doped with boron B or phosphorus P).

[0054] Preferably, the first negative contact Cn1 is located close to the outer periphery P1 of the substrate 28 in which the photovoltaic cells are to be fabricated. The positive complementary contact Cp1 is also fabricated, for example, close to the outer periphery of the wafer, slightly set back from the first negative contact Cn1. Starting from each of the contacts Cn1 and Cp1, at least two conductive pins or preferably two conductive combs 25, 25' are formed whose teeth are intended to interdigitate alternately, side by side, on the same surface on the back side of the substrate 28. If the substrate 28 has a circular shape, this means that the holding lines of each tooth of each comb 25, 25' represent arcs starting from the contacts Cn1 and Cp1, respectively, in opposite directions.

[0055] The interdigitated design may be substituted for other designs. Furthermore, the interdigitated design is not required to create, for example, a dual coil.

[0056] The second or other negative contact Cn2 is made between at least two conductive pins or conductive teeth of the comb without electrical contact with either of them. As shown in FIG. 5A, the second contact Cn2 can be located after the last tooth of the comb 25′. Furthermore, to insulate the last tooth from the rest of the comb 25′, the last two teeth 25, 25′ are preferably divided P3 from the rest of the comb. It can be clearly seen that this division P3 allows for the isolation of the second photovoltaic cell from the first photovoltaic cell. However, it should be noted that the small area in which the IBC-type second photovoltaic cell or solar cell is intended to be made must be clearly defined. However, it should be noted that this second photovoltaic cell or solar cell is necessarily smaller than the first photovoltaic cell or solar cell used for capturing and converting light energy into electrical energy.

[0057] This second embodiment or variant is more complex to implement or perform in measuring the open circuit voltage, but it does constitute one variant to be considered.

[0058] The present invention offers the great advantage of allowing frequent and even permanent measurements of the voltage Voc so as to be able to quickly adapt to the operating point Vmpp, which is all the more important when lighting conditions change quickly and frequently, and when a watch, the dial of which typically comprises a first photocell and a second photocell measuring the open-circuit voltage, is worn by an active user.

[0059] It should be noted that in the first variant, the production of the miniature battery can be done very easily within the normal production steps, without significantly increasing the duration of the process. Furthermore, the aesthetics of the first variant are less of an issue, since the openings produced are filled with a dark resin, thereby reducing the visual contrast.

[0060] As in the first variant, the electrical connection terminals can be reversed depending on the arrangement of the electronic circuits connected to these photovoltaic cells. For this purpose, a common contact pad can be provided to the ground rather than the positive terminal of the power supply. This leaves a positive variation when adapting the voltage at the first photovoltaic cell or solar cell that generates the electrical energy for the general power supply of such circuits or modules. This also makes it possible to determine the correct operation of the module and its circuits by varying the open-circuit voltage through adaptation.

[0061] Naturally, several contact pads Cn1, Cn2, Cp1 may be provided on the wafer to ensure uniform polarization of each part for proper operation of the module 1. When creating a conductive comb from the first contact pad Cn1 and the complementary contact pad Cp1, the arrangement of the teeth of the two combs from the connecting wires of these teeth should be fairly regular for good distribution or polarization of the wafer. It is conceivable that each comb starts from a contact pad located on the periphery of the wafer or approximately in the center of the wafer, but the teeth of each comb still alternate on the back contact surface of the wafer. It is also possible to consider arranging the contact pads of each comb on the periphery, substantially 180° relative to each other. However, the embodiment shown in FIG. 5B seems more conceivable, and the arrangement of the teeth of the illustrated conductive comb provides good polarization distribution. The length of each tooth may extend more than that shown in FIG. 5B.

[0062] The principles described above, aimed at facilitating the measurement of the open-circuit voltage (Voc), can also be implemented to measure another key parameter of a photovoltaic cell: its short-circuit current (Isc). Knowing this current also allows for optimization of the operating point, but in practice, the open-circuit voltage (Voc) is preferred. This open-circuit voltage (Voc) is equal to In (I). However, among other things, the short-circuit current (Isc) varies almost linearly with illumination intensity, allowing for the easy implementation of a lux meter function. If the overall behavior of the system capturing and converting light to electrical energy is known, integrating the measurement into a lux meter allows for the estimation of the amount of energy collected. This energy estimation is useful information for optimizing energy management and informing the end user of the product.

[0063] It should also be remembered that this maximum power Pmpp corresponds to the operating point MPP, which is characterized by a very specific voltage Vmpp and current Impp, which depend on the illumination level. The maximum power point Pmpp tracking function described previously is related to the voltage of the small battery, which can also mimic the lux meter function in two different ways: - The open-circuit voltage Voc of the photovoltaic cell is a signal proportional to the logarithm of the irradiation. All that is required for the open-circuit voltage Voc of the photovoltaic cell is to measure the value for estimating illumination by means of a look-up table (voltage->lux). - Alternatively, when a small resistor (<<Vmpp / Impp) is placed in parallel with the small photovoltaic cell, the small photovoltaic cell yields a voltage proportional to the irradiation. All that is required for the open-circuit voltage Voc of the photovoltaic cell is to measure the value for estimating illumination by means of a look-up table (voltage->lux).

[0064] It should also be noted that the open-circuit voltage can be a measured value that takes into account the illumination intensity of the photovoltaic cell set.

[0065] The small resistor can "shunt" from the small photovoltaic cell in order to measure the voltage proportional to the operation or the short-circuit current. This results in a linear variation of the current and voltage.

[0066] Of course, those skilled in the art may consider other possible embodiments of the photovoltaic cell set without departing from the scope of the invention defined by the claims.

Description of Symbols

[0067] 1 Photovoltaic cell module 2 Photovoltaic cell 3 Electronic circuit 10 Set 12 Photovoltaic cell 21 Conductive layer 22 Substrate 23 Conductive layer 25 Conductive layer 25’ Conductive layer 28 Substrate

Claims

1. A photovoltaic module (1) having a photovoltaic cell set (10) and an electronic circuit (3), The photovoltaic cell set (10) comprises at least one first photovoltaic cell (2) configured to capture light energy that is converted into electrical energy in the photovoltaic module (1), and at least one second photovoltaic cell (12) independent of the first photovoltaic cell (2) configured to measure voltage or current in the photovoltaic module (1), wherein the size of the second photovoltaic cell (12) is smaller than the size of the first photovoltaic cell (2); The photovoltaic cell set (10) comprises a substrate or support, an insulation (P3), and at least one conductive layer on the top surface of the substrate or support or on the bottom surface of the substrate or support for establishing electrical contacts between the first photovoltaic cell (2) and the second photovoltaic cell (12), wherein the substrate or support, the insulation (P3), and the conductive layer constitute at least a part of the first photovoltaic cell (2) and / or the second photovoltaic cell (12); The conductive layer is a first conductive layer (21) disposed on the top surface of the substrate or the support, and the photovoltaic cell set (10) comprises a second conductive layer (23) disposed on the bottom surface of the substrate or the support; the first conductive layer (21) is transparent and is intended to fix the substrate below the surface of the support of the photovoltaic cell set (10); The second conductive layer (23) is connected to the first conductive layer (21) by a peripheral opening of the photovoltaic cell set (10) formed in the substrate or in the first photovoltaic cell (2); The insulation (P3) is made to define the first photovoltaic cell (2), and another insulation (P13) is made to separate the second photovoltaic cell (12) from the first photovoltaic cell (2), allowing the second photovoltaic cell (12) to measure the voltage or current within the photovoltaic module (1). A photovoltaic module (1) characterized in that:

2. 2. Photovoltaic module (1) according to claim 1, characterized in that the first photovoltaic cell (2) is a thin-film cell.

3. 2. Photovoltaic module (1) according to claim 1, characterized in that the material of the first photovoltaic cell (2) is amorphous silicon.

4. 2. The photovoltaic module (1) of claim 1, wherein the photovoltaic cell set (10) comprises a positive contact (Cp1), a negative contact (Cn1), and another negative contact (Cn2), the positive contact (Cp1) being arranged on the second conductive layer (23) at the periphery of the substrate or support, intended to enable polarization of the first conductive layer (21) at the same positive potential of the first photovoltaic cell (2) and the second photovoltaic cell (12), the negative contact (Cn1) being arranged on the first photovoltaic cell (2) on the substrate via the second conductive layer (23), and the another negative contact (Cn2) being arranged on the second photovoltaic cell (12) on the substrate via the second conductive layer (23).

5. 2. The photovoltaic module (1) according to claim 1, characterized in that the visible part of the photovoltaic cell set (10) is made in the same color as the first photovoltaic cell (2) and / or the second photovoltaic cell (12).

6. A photovoltaic module (1) having a photovoltaic cell set (10) and an electronic circuit (3), The photovoltaic cell set (10) comprises at least one first photovoltaic cell (2) configured to capture light energy to be converted into electrical energy in the photovoltaic module (1), and at least one second photovoltaic cell (12) independent of the first photovoltaic cell (2) configured to measure voltage or current in the photovoltaic module (1), wherein the size of the second photovoltaic cell (12) is smaller than the size of the first photovoltaic cell (2); The photovoltaic cell set (10) comprises a substrate, a conductive layer, p-type and n-type regions, a first comb (25) and a second comb (25'), wherein the substrate, the conductive layer, the p-type and n-type regions, and the first comb (25) and the second comb (25') constitute at least a part of the first photovoltaic cell (2) and / or the second photovoltaic cell (12), the p-type and n-type regions are formed alternately in parallel on the back of the substrate, the conductive layer is arranged on the p-type and n-type regions while defining the first comb (25) and the second comb (25'), the teeth of the first comb (25) are arranged on the p-type regions, and the teeth of the second comb (25') are arranged on the n-type regions, The photovoltaic cell set (10) comprises a first positive contact (Cp1), a first negative contact (Cn1), and an insulating divider (P3), wherein the first comb (25) is connected to the first positive contact (Cp1), while the second comb (25') is connected to the first negative contact (Cn1) associated with the first photovoltaic cell (2), and two teeth of the first comb (25) and the second comb (25') are insulated from other teeth of the first comb (25) and the second comb (25') by the insulating divider (P3). A photovoltaic module (1) characterized in that:

7. 7. The photovoltaic module (1) of claim 6, characterized in that the photovoltaic cell set (10) comprises at least one passivation layer (27) arranged directly on the upper surface of the substrate, and the conductive layer is arranged on the lower surface of the substrate.

8. Photovoltaic module (1) according to claim 6, characterized in that the substrate is a crystalline substrate made of silicon.

9. 8. Photovoltaic module (1) according to claim 7, characterized in that the photovoltaic cell set (10) comprises an anti-reflection layer (26) arranged on the passivation layer (27).

10. 7. Photovoltaic module (1) according to claim 6, characterized in that the p-type and n-type regions and the first (25) and second (25') combs are linear.

11. 7. Photovoltaic module (1) according to claim 6, characterized in that the p-type and n-type regions and the first (25) and second (25') combs are curved or arcuate.

12. 2. Photovoltaic module (1) according to claim 1, characterized in that the first photovoltaic cell (2) forms the dial of a watch or is bonded to the dial or glass of a watch.

13. 2. The photovoltaic module (1) according to claim 1, characterized in that the first photovoltaic cell (2) and the second photovoltaic cell (12) are fabricated in one or more of the substrates which are silicon wafers, or on one or more of the supports of a material made of glass, plastic or metal together with an insulating layer, or on a crystalline layer.

14. The photovoltaic module (1) according to claim 1 or 6, further comprising a switching controller (5) in the electronic circuit (3) and an adapter (4) connected to the switching controller (5).

15. 15. Photovoltaic module (1) according to claim 14, characterized in that the voltage measured is the open circuit voltage (Voc) of the second photovoltaic cell (12), which is a signal proportional to the logarithm of the illumination.

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