WO2022112069A1

WO2022112069A1 - Device for measuring the quality of a photovoltaic component and associated method

Info

Publication number: WO2022112069A1
Application number: PCT/EP2021/081932
Authority: WO
Inventors: Damien BARAKEL
Original assignee: Université D'aix-Marseille; Centre National De La Recherche Scientifique
Priority date: 2020-11-24
Filing date: 2021-11-17
Publication date: 2022-06-02
Also published as: FR3116678A1; FR3116678B1

Abstract

The proposed method relates to a device for measuring the quality of a photovoltaic component (CP), the device comprising: a modulation element (23) for modulating, at a predetermined frequency, incident light on at least one portion of the photovoltaic component, the portion being referred to as the tested zone; and a unit (24) for measuring the strength of the current induced in the photovoltaic component by means of the modulated incident light, the intensity being representative of the quality of the tested zone. According to the proposed method, the modulation element is in the form of a plate suitable for being directly placed or flush mounted on the photovoltaic component (CP). The plate comprises at least one modulation zone configured to periodically alternate, at the predetermined frequency, between two states: an exposure state wherein the modulation zone enables the light to pass through the plate in the modulation zone; and a closed state wherein the modulation zone prevents the light from passing through the plate in the modulation zone.

Description

DESCRIPTION

TITLE: Device for measuring the quality of a photovoltaic component, associated process.

Technical area

The field of the invention is that of diagnostic devices making it possible to assess the quality of photovoltaic components, such as photovoltaic cells or panels for example. The invention lies more particularly in the field of quality measurement devices based on a technique of characterization by induced currents.

Prior art

The LBIC technique - from the English "Light Beam Induced Current", "current induced by light beam" in French - is a characterization technique known and used in the field of photovoltaics, in order to evaluate the quality of components such as a photovoltaic cell or panel for example. This technique makes it possible in particular to highlight and locate any defects in the photovoltaic component tested (manufacturing defects, impacts, aging, etc.), which are often the cause of degradation in the performance of the component. The general principle of the LBIC characterization technique is based on the photovoltaic effect of certain semiconductor materials used in these components, which results in the appearance of a current at the terminals of the photovoltaic component exposed to light. More particularly, this technique consists in locally illuminating, by means of a modulated light beam, an area of the photovoltaic component to be tested, then in isolating and measuring the current induced in response to this localized light excitation. By scanning the surface of the photovoltaic component in this way, a complete map of these induced photocurrents is drawn up, which can be assimilated, under certain conditions, to an image of the quality of this component.

Figure la illustrates, schematically and partially, a device for measuring the quality of a photovoltaic component based on the LBIC technique (also called more simply "LBIC device" in the rest of the document), as existing in the prior art. Such a device comprises a unit 11 for generating a modulated light beam 12 used to illuminate a very localized zone Z of the photovoltaic component CP′ to be tested, which is moreover immersed in darkness, as well as a unit for measuring the intensity of the current induced by the photovoltaic effect in response to this light excitation. The generation unit 11 comprises a polychromatic light source 111 (possibly associated with a monochromator) or monochromatic (eg a laser). The generation unit 11 also comprises a modulation element 112, also called an optical chopper, used to periodically interrupt the light beam produced by the light source 111. As illustrated in FIG. a pierced disc rotating in the light beam at a controlled speed. In this way, the light beam 12 is modulated (ie "cut") at a well-defined frequency, which makes it possible, by implementing synchronous detection techniques commonly used in the field of signal processing, to isolate level of the measurement unit 14 the current actually induced by the modulated light beam 12. Since the tests are in fact not carried out in absolute darkness (very difficult to achieve in practice), the input of the measurement unit 14 therefore corresponds to a juxtaposition of several currents, not only that induced by the modulated light beam 12 but also other currents induced by parasitic light sources other than the light source 111. The synchronous detection technique then consists, at the level of the measurement unit 14, to filter and ignore all the currents of frequencies different from the modulation frequency of the modulated light beam 12, defined thanks to the modulation element 112. These parasitic currents your are thus discarded, and only the current induced by the light beam emitted by the generation unit 111 is measured at the level of the measurement unit 14.

The generation unit 11 of the modulated light beam also generally comprises various other elements, not shown in FIG. a very small surface of the photovoltaic component CP' to be tested. The photovoltaic component CP′ is also mounted on a precision table, the movement of which in a plane perpendicular to the modulated beam 12 can be controlled very finely. In this way, it is possible to scan, by means of the modulated beam 12, the entire surface of the photovoltaic component CP′ to be tested, and thus to obtain, by consolidating all the associated measurements carried out by the measurement unit 14, a complete map of the intensity of the photocurrents induced in this component (the width of the modulated beam defining, to a certain extent, the resolution of the image obtained). Figure lb shows an example of mapping (in a partial view and not to scale) obtained through the use of such an existing LBIC device to test a crystalline silicon photovoltaic cell under polychromatic light, with a resolution of 50 pm. Such a map can be likened to an image of the quality of the photovoltaic component, the areas associated with abnormally low current intensities or abnormally high being more particularly likely to present defects.

Most of the existing LBIC measurement devices are however very bulky and non-transportable equipment. The complexity of the means implemented to generate a light beam with characteristics (wavelength, power, section, etc.) controlled and constant throughout the measurements, a guarantee of their quality, mean that the beam generation unit luminous is a particularly sophisticated and voluminous element of these conventional devices. Furthermore, in order to avoid stray light as much as possible, the measurements must be carried out in the dark. These constraints, which relate both to the measurement device as such and to the conditions for carrying out the measurements, mean that the evaluation of the quality of a photovoltaic component by an LBIC characterization technique cannot generally be carried out in -situ: the photovoltaic component to be tested must be dismantled and transported to a dedicated site (e.g. a laboratory) which hosts the LBIC device, which is not without posing certain problems, in particular when it comes to testing large surfaces such as potentially large photovoltaic panels (costs and risks associated with dismantling, transporting and reassembling the photovoltaic component, long unavailability of the photovoltaic component, involving a prolonged stoppage of the production of electrical energy, risks of damage to the photovoltaic component during the many necessary handling operations, etc.).

There is therefore a need for a device for measuring the quality of a photovoltaic component which does not have at least some of these disadvantages of the prior art.

Summary of the invention

The present technique makes it possible to partly solve the problems posed by the prior art. The present technique in fact relates to a device for measuring the quality of a photovoltaic component, said device comprising: a modulation element for modulating, at a predetermined frequency, light incident on at least part of said component photovoltaic, called tested area; a unit for measuring the intensity of the current induced in said photovoltaic component by said modulated incident light, said intensity being representative of the quality of the zone tested. According to the proposed technique, said modulation element takes the form of a plate adapted to be placed directly or mounted flush on said photovoltaic component, said plate comprising at least one modulation zone configured to alternate periodically, at said predetermined frequency, between two states: an exposure state in which the modulation zone allows the passage of light through said plate, at the level of said modulation zone; a closed state in which the modulation zone blocks the passage of light through said plate, at the level of said modulation zone.

In a first particular embodiment of the proposed technique, said modulation zone extends substantially over the entire surface of said plate, and said modulation zone is formed by superimposing two grids, a fixed grid and a mobile grid, each of the two grids comprising a succession of optically transparent portions and of opaque portions, said mobile grid being configured so as to be mobile between at least a first position, corresponding to said exposure state, in which the optically transparent portions of the two grids overlap at least partially, and at least a second position, corresponding to said closed state in which the opaque portions of any one of the two grids completely block the optically transparent portions of the other of the two grids.

According to a particular characteristic of this first embodiment, said plate has dimensions substantially equivalent to the standard dimensions of a photovoltaic cell of a photovoltaic panel.

In a second particular embodiment of the proposed technique, said plate takes the form of a matrix of independently controllable liquid crystal shutters, said matrix comprising at least one liquid crystal shutter, each liquid crystal shutter of said matrix being a shutter with two states, a state in which the shutter allows light to pass and a state in which the shutter blocks light, and in that said modulation zone is formed by a set of shutters with adjacent liquid crystals of said matrix, said assembly comprising at least one liquid crystal shutter.

According to a particular characteristic of this second embodiment, said array of liquid crystal shutters comprises a single liquid crystal shutter extending over substantially the entire surface of said plate and defining said modulation zone.

According to a particular characteristic of this second embodiment, said plate has dimensions substantially equivalent to the standard dimensions of a photovoltaic cell of a photovoltaic panel.

According to another particular characteristic of this second embodiment, said matrix of liquid crystal shutters comprises a plurality of liquid crystal shutters, and said plate is of dimensions substantially equivalent to the standard dimensions of a photovoltaic panel.

In a particular embodiment, said modulation element further comprises means for optical filtering of said incident light, as a function of the wavelength.

According to another aspect, the proposed technique also relates to a method for measuring the quality of a photovoltaic component by means of a measuring device as previously described, said photovoltaic component being illuminated only by natural sunlight. Said method comprises at least one iteration of the following steps: a step of positioning the modulation element of said measuring device directly in contact with an area comprising at least one area to be tested of said photovoltaic component; a step of activating the alternation, at a predetermined frequency, of the modulation zone of said modulation element, between its exposure state and its shutter state. a step of measuring, by the measuring unit of said measuring device, the intensity of the current induced in the photovoltaic component by the natural light modulated by said modulation zone.

In a particular embodiment, said method further comprises, prior to said activation step, when said modulation element of said measuring device takes the form of a matrix comprising a plurality of liquid crystal shutters, a step of selecting a set of adjacent liquid crystal shutters of said array, including at least one liquid crystal shutter, defining said modulation area.

The various embodiments mentioned above can be combined with each other for the implementation of the invention.

tricks

Other characteristics and advantages of the invention will appear more clearly on reading the following description of a preferred embodiment of the invention, given by way of a simple illustrative and non-limiting example, and the appended drawings, among which:

[Fig la], already described in relation to the prior art, schematically and partially presents an existing measuring device based on the LBIC characterization technique, in use for the evaluation of the quality of a component photovoltaic ; [Fig lb], already described in relation to the prior art, presents an example of mapping of the intensity of the currents induced in a photovoltaic component, as obtained after scanning the surface of a photovoltaic component by an LBIC device such as that shown in Figure la;

[Fig 2] schematically and partially presents a device for measuring the quality of a photovoltaic component, in a particular embodiment of the proposed technique;

[Fig 3a] schematically illustrates a possible implementation of a modulation element of a device according to the proposed technique, formed by superimposing two complementary grids, in a particular embodiment;

[Fig 3b] presents an example of two grids (in (a) and (b)) adapted for the implementation of a modulation element, as well as the modulation element obtained by superimposing these two grids, in a closed state (in (c)) and in an exposed state (in (d)), in a particular embodiment of the proposed technique;

[Fig 3c] presents another example of grids suitable for the implementation of a modulation element, in a particular embodiment;

[Fig 4a] shows a modulation element with dimensions smaller than the standard dimensions of a photovoltaic cell, in a particular embodiment of the proposed technique; [Fig 4b] shows a modulation element with dimensions greater than the standard dimensions of a photovoltaic cell, in a particular embodiment of the proposed technique; [Fig 5] schematically and partially presents a device for measuring the quality of a photovoltaic component, in another particular embodiment of the proposed technique;

[Fig 6] schematically illustrates another possible implementation of a modulation element of a device according to the proposed technique, formed of a single liquid crystal shutter, in a particular embodiment;

[Fig 7] schematically and partially presents a device for measuring the quality of a photovoltaic component, in yet another particular embodiment of the proposed technique, in which the modulation element is formed of a matrix comprising a plurality of liquid crystal shutters;

[Fig 8] schematically and partially presents a device for measuring the quality of a photovoltaic component, in another particular embodiment of the proposed technique, in which the modulation element is formed of a matrix comprising a plurality liquid crystal shutters, and has the standard dimensions of a photovoltaic panel;

[Fig 9] schematically and partially shows the measuring device of figure 8, in use to assess the quality of a photovoltaic panel comprising cells in the form of strips, in a particular embodiment of the technique proposed;

[Fig 10] illustrates the main steps of a method for measuring the quality of a photovoltaic component, in a particular embodiment of the proposed technique.

Detailed description of the invention

The present technique relates to a device for measuring a photovoltaic component which is based on the LBIC characterization technique previously presented in relation to the prior art. As described below in relation to various embodiments, the proposed measuring device nevertheless has particular characteristics allowing it to overcome many constraints of existing conventional LBIC devices.

Throughout the description and in the figures, elements of the same type are identified by the same reference.

A measuring device according to the proposed technique is illustrated in relation to FIG. 2 in an example of use for measuring the quality of a photovoltaic component CP, in a particular embodiment. The photovoltaic component CP is typically a photovoltaic panel grouping together a plurality of photovoltaic cells (C1, C2, C3, ..., Cn) interconnected in series and/or in parallel.

Like the conventional LBIC devices of the prior art, the measuring device according to the technique proposed comprises a modulation element 23 for the modulation, at a predetermined frequency, of light incident on at least part of the photovoltaic component tested CP, as well as a measurement unit 24 of the intensity of the current induced in the photovoltaic component CP by said modulated incident light (this intensity being representative of the quality of the zone tested, i.e. of the zone of the photovoltaic component which receives the modulated light ). The predetermined modulation frequency is typically of the order of a few hundred hertz (it is generally less than 1000 Hz), its value being able to be adapted according to the photovoltaic component tested.

The measuring device according to the proposed technique differs, however, from those of the prior art in that the modulation element 23 takes the form of a plate adapted to be placed directly (or at the very least mounted flush) on the surface to be tested of the photovoltaic component, said plate comprising at least one ZM modulation zone configured to periodically alternate, at said predetermined frequency, between two states: an exposure state in wherein the ZM modulation zone allows light to pass through said plate at said modulation zone; a closed state in which the ZM modulation zone blocks the passage of light through said plate at the level of said modulation zone.

In the context of the proposed technique, the term "plate" means a part (possibly formed by assembling several parts) substantially flat (or at the very least flat over a major part of its surface), the thickness of which is small in comparison with its other dimensions. As such, the modulation element 23 can be described as a “flat” element. Typically, by way of non-limiting example, a plate is, for example, of rectangular parallelepipedic shape, with a low thickness with respect to its length and its width. Other shapes of plates can however be envisaged, for example a circular plate. The fact that the modulation element is flat and thin (possibly with other characteristics such as low weight for example) contributes to making this element suitable for being placed directly in contact with the surface of the photovoltaic component: d on the one hand, its flat surface makes it possible to maximize the coverage of the area to be tested of the photovoltaic component (the latter also having a generally flat surface), and on the other hand, its small thickness makes it possible to minimize the influence of the modulation element on the light incident on the photovoltaic component, when the modulation element is in its exposure state.

The use of a modulation element intended and adapted to be placed directly on the photovoltaic component (ie directly in contact with it, or at the very least almost in contact with it) offers the main advantage, with respect to the devices existing measuring devices as presented in relation to the prior art, to make it possible to assess the quality of the photovoltaic component to be tested without it being necessary to place it in a dark room, and without it being necessary to resort to to a dedicated unit for generating a light beam (such as the dedicated generation unit 11 already described in relation to FIG. 1a, for example). More particularly, as illustrated in FIG. 2, a major advantage of the proposed technique resides in the possibility of directly using natural light 22 (ie sunlight 21) as a light source, rather than artificial light generated by means of of complex, bulky equipment, difficult to transport and expensive such as that necessary and integrated into existing conventional LBIC devices. Unlike these devices of the prior art, the measuring device according to the proposed technique therefore does not include a dedicated light source, which would be an integral part thereof. This has many advantages, especially when the photovoltaic component to be tested is large (for example a photovoltaic panel whose dimensions sometimes exceed one meter in width and two meters in length), and potentially already installed and in the operating phase. . The measurement device according to the proposed technique thus makes it possible in particular to carry out quality measurements "in-situ", that is to say at the very place where the photovoltaic component is installed and operational, generally outdoors. It is no longer necessary to disassemble the photovoltaic component and transport it to a dark room housing dedicated fixed equipment to test it. This overcomes the many constraints and many risks associated with the use of existing LBIC devices already described in relation to the prior art (costs and risks associated with dismantling, transport and reassembly of the photovoltaic component, significant downtime of the photovoltaic component, involving a prolonged shutdown of the production of electrical energy, risk of damage to the photovoltaic component during the numerous handling operations required, etc.). The device according to the technique proposed is moreover not only transportable, but it is also much less expensive than a device of the prior art.

It should be noted that, within the framework of the proposed technique, the role and operation of the measuring unit 24 are not fundamentally different from those of the measuring unit 14 as described in relation to the figure illustrating a prior art LBIC device. This measurement unit 24 is also intended, by implementing synchronous detection techniques, to isolate and measure the current induced in the photovoltaic component by the light modulated by the modulation element 23 of the LBIC device. The measurement unit 24 and the processing it performs are at most the subject of adaptations to take into account the fact that the luminous power of the sun is greater than the power of the artificial light sources usually used in prior art devices. Also, the measurement unit 24 is not described in more detail in this document.

We now present different possible implementations for the implementation of the modulation element 23, in different particular embodiments of the proposed technique. According to a first implementation, in particular embodiments illustrated in relation to FIGS. 3a, 3b and 3c, the modulation element 23 is formed by superimposing two grids each comprising a succession of optically transparent portions and opaque portions. The ZM modulation zone then extends substantially over the entire surface of the modulation element 23 (ie of the plate). According to the proposed technique, one of these grids is fixed (if we consider a frame of reference linked to the modulation element), and the other is mobile in translation or in rotation above (or below) the fixed grid, the two grids being moreover very close, even in contact with one another. The optically transparent portions (corresponding for example to simple orifices in the grid) and the opaque portions are also positioned, shaped and dimensioned within each of the two grids so that there is at least one position of the grid mobile, called exposure position, in which the optically transparent portions of the two grids overlap at least partially, and at least one position of the mobile grid, known as the shutter position, in which the opaque portions of any of the two grids completely block all the optically transparent portions of the other of the two grids (in other words, in the closed position, the opaque portions of the mobile grid are superimposed on the optically transparent portions of the fixed grid and vice versa). In this way, the exposure position corresponds to an exposure state in which the two grids are respectively positioned opposite each other so as to let the light pass, while the position of shuttering corresponds to a shuttered state in which the two grids are positioned respectively one vis-à-vis the other so as to block the passage of light. According to a particular characteristic, a controlled oscillation of the movable gate at a predetermined frequency then allows the transition from the exposure state to the shutter state and vice versa, and therefore the modulation of the light which passes through the modulation zone. (which covers the entire modulation element, in the particular embodiment considered).

FIG. 3a schematically presents, in a perspective view, such an arrangement, in which the modulation element 23 is formed by superimposing a first grid 31, fixed, and a second grid 32, mobile in translation above above the first grid 31. To facilitate understanding, the two grids 31 and 32 are shown relatively spaced apart in Figure 3a (and in all the figures relating to this implementation of the modulation element in general), but it it is understood that the two grids are actually sufficiently close, even in contact, so as to jointly form an opaque modulation element when the grid He mobile 32 is in its closed position.

FIG. 3b shows, in a top view and in a particular embodiment, an example of two complementary grids 3 and 32' (sub-figures (a) and (b)) adapted for the implementation of an element modulation according to this implementation of the proposed technique, as well as the modulation element 23 obtained by superimposing these two grids, in a shutter state (sub-figure (c)) and in an exposure state (sub- figure (d)). In this illustrative and non-limiting example, the grids 3 and 32' have the same dimensions and are formed by a succession of opaque bands (bands shown shaded in the sub-figures (a) and (b)) and optically transparent bands ( bands shown white in sub-figures (a) and (b)) of the same width. The opaque bands are for example formed from an opaque material, and the optically transparent bands from a transparent material or even by simple absence of material between the opaque bands. In the example represented in FIG. 3b, the modulation element 23 obtained by superposition of the two grids 3 and 32' is completely opaque when the grids 3 and 32' are perfectly superimposed (sub-figure (c)), and it leaves pass the light when the grids 3 and 32' are superimposed over their major part, but with one of the grids shifted by the width of a strip with respect to the other grid (sub-figure (d)) .

The modulation element 23 also comprises means (not shown) for moving in translation one of the two grids (for example the grid 32') vis-à-vis the other grid (for example the grid 3) . These displacement means, controlled by a control unit of the measuring device, make it possible to implement a controlled oscillation of the mobile grid 32' (typically an oscillation of low amplitude, of the width of a strip) at a predetermined frequency - causing the modulation element 23 to alternate between its exposed state and its shuttered state - which has the effect of modulating the light received (typically sunlight) at the level of the zone to be tested from the photovoltaic component, on which the modulation element 23 is placed directly.

Of course, other types of grids can be envisaged, in particular as regards the shape of the optically transparent portions and the opaque portions, as illustrated for example in relation to FIG. 3c which presents another example of two complementary grids 31" and 32" also suitable for the implementation of a modulation element according to the proposed technique. In another particular embodiment, the two grids can also for example be circular, with a mobile grid in rotation above (or below) the fixed grid. According to a particular characteristic, as illustrated for example in FIG. 2, the modulation element 23 - that is to say the plate formed by superimposing the two grids - has dimensions (length and width) substantially equivalent to the standard dimensions of a photovoltaic panel photovoltaic cell. The modulation element is for example square, and of dimensions 125 mm by 125 mm, 156 mm by 156 mm, 156.75 mm by 156.75 mm, or even 158.75 mm by 158.75 mm, which correspond to standard dimensions for a photovoltaic cell. These examples are however not limiting, and the modulation element can take other shapes (rectangular, circular, etc.) and have other dimensions, depending on the type of standard photovoltaic cell targeted. In this way, the measurement device according to the proposed technique makes it possible to evaluate the quality of each cell of a photovoltaic panel, one after the other, by moving the modulation element 23 from cell to cell on the panel. and by carrying out each time, by means of the measuring unit 24, a measurement of the intensity of the current induced at the level of the cell tested by the modulated sunlight. It is thus possible to quickly detect a defective cell or one of lesser quality on a photovoltaic panel. By consolidating these measurements, it is also possible to draw up a complete map of the intensity of the photocurrents induced in the photovoltaic component. Such a map associates with each zone tested (eg with each cell) the value of the intensity of the associated induced current measured by the measurement unit 24. This map can in particular take the form of an image in which a given color or a given level of gray corresponds to a value or an interval of measured intensity values (in a manner similar to the cartography already presented in relation to FIG. 1b of the prior art). The example of a plate with the standard dimensions of a photovoltaic cell of a photovoltaic panel is however non-limiting, and other plate sizes can be envisaged, as illustrated in relation to FIGS. 4a and 4b for example. The choice of the size of the plate used can in particular be likened to the choice of a resolution for measuring the quality of the photovoltaic component. Thus, by way of illustration, a complete mapping of the intensity of the photocurrents induced in the photovoltaic component, at the resolution of the half-cell, can be obtained by carrying out, by means of a plate the size of a half- cell, enough successive measurements to test the entire surface of the photovoltaic component. By having several plates of different sizes, it is in particular possible, for example, to carry out a first rapid analysis of the quality of a photovoltaic component as a whole with low resolution (by using the larger modulation element, for example the modulation element 23" of FIG. 4b, for draw up an initial "coarse mesh" map - ie at low resolution - of the photovoltaic component as a whole) in order to quickly identify an area potentially of lower quality, then to analyze more finely (with a higher resolution) the previously problematic area identified (by using smaller-sized modulation elements, for example the modulation element 23 of FIG. 2, then the modulation element 23' of FIG. 4a, in order to produce increasingly fine maps - ie at higher and higher resolutions - targeted problem areas).

We now illustrate, in particular embodiments illustrated in relation to FIGS. 5 to 9, a second possible implementation of the modulation element 23 (i.e. the plate), which then takes the form of a matrix of shutters with liquid crystals (including at least one liquid crystal shutter). In this case, the plate can also be described as a "slab". Each liquid crystal shutter in the array is a shutter that can assume either of two states, depending on the voltage to which it is subjected: a state in which the shutter has some degree of transparency and lets light through, and a state in which the shutter is opaque and does not let light through. The transition from one state to another is achieved by modifying the voltage applied to the terminals of the shutter, which has the effect of modifying the orientation of the molecules of the liquid crystals of the shutter. For example, the shutter allows a maximum of light to pass when a zero voltage is applied to its terminals, and the shutter is opaque when a voltage greater than a certain threshold is applied to its terminals. Furthermore, according to the proposed technique, each liquid crystal shutter of the matrix is independently controllable.

In a particular embodiment illustrated in relation to FIG. 5, the matrix of liquid crystal shutters comprises a single shutter OB, which defines a modulation zone ZM extending over the entire surface of the modulation element 23. As represented in FIG. 6, the application of a voltage in a predetermined frequency square to the terminals of this shutter OB (via a control unit of the measuring device for example) causes the alternation of the modulation element 23 between its shutter state (subfigure (a)) and its exposure state (subfigure (b)). This has the effect of modulating the light received (typically sunlight) at the level of the area to be tested of the photovoltaic component, on which the modulation element 23 is placed directly.

According to a particular characteristic of this embodiment, and as illustrated for example in FIG. 5, the modulation element 23 - that is to say the plate comprising the shutter OB - is of dimensions substantially equivalent to the standard dimensions of a photovoltaic cell of a photovoltaic panel. The modulation element is for example square, and of dimensions 125 mm by 125 mm, 156 mm by 156 mm, 156.75 mm by 156.75 mm, or even 158.75 mm by 158.75 mm, which correspond to standard dimensions for a photovoltaic cell. These examples are however not limiting, and the modulation element can take other shapes (rectangular, circular, etc.) and have other dimensions, depending on the type of standard photovoltaic cell targeted. Other slab sizes, which do not correspond to standard photovoltaic cell dimensions, can obviously be envisaged. We then find the advantages already described in relation to the first implementation, in the form of superimposed grids, of the modulation element 23, and in particular the possibility of being able to carry out measurements of the quality of the photovoltaic component at different resolutions (according to the size of the slab chosen), and to draw up associated maps of the intensity of the photocurrents induced in this component.

With panels with a single liquid crystal shutter, changing the resolution means having several panels of different sizes. It is however possible to overcome this constraint at least partially by using a modulation element in which the matrix of liquid crystal shutters comprises a plurality of liquid crystal shutters, as illustrated for example in relation to FIG. in a particular embodiment of the proposed technique. In this illustrative and non-limiting example, the modulation element 23, of dimensions substantially equivalent to the standard dimensions of a photovoltaic cell of a photovoltaic panel, is formed by a matrix of four liquid crystal shutters 01, 02, 03 and 04 of same dimensions, divided into two rows of two shutters. Such an arrangement based on a plurality of independently controllable shutters is interesting in that it allows, from a single and same panel, to perform measurements at different resolutions. The modulation element 23 represented in FIG. 7 thus makes it possible to carry out measurements at the resolution of the cell, of the half-cell, or even of the quarter of a photovoltaic cell. For example, to perform a measurement with a quarter-cell resolution, it suffices, by means of the control means of the measurement device, to define the shutter 01 as modulation zone (the shutter 01 then alternates between its state exposure and its shutter state at a predetermined frequency) and to freeze the other shutters 02, 03 and 04 in the same constant state, for example in their exposure state. Once the induced current measurement has been performed in this configuration by the measurement unit 24, it is possible, without move the slab, to test another quarter of the cell on which the modulation element 23 is placed (for example, this time selecting shutter 02 as modulation zone, and freezing the state of shutters 01, 03 and 04). It is also possible to define a group of (usually adjacent) shutters as a modulation zone: all shutters in the modulation zone are then driven to alternate synchronously and coherently between their exposure state and their dim state. shutter, at the predetermined frequency. For example, by selecting the group of shutters 01 and 03 as modulation zone and by freezing the state of shutters 02 and 04, a measurement is carried out at the resolution of the half-cell. By selecting all the shutters (ie 01, 02, 03 and 04) as modulation zone, we find measurement conditions similar to those already described in relation to FIG. 5, with measurements at the resolution of the cell. Once the desired measurements have been taken on a cell, the modulation element 23 can be physically moved to another cell to be tested of the photovoltaic component CP. In this embodiment, the same tile can therefore be used to draw up complete maps of the intensity of the photocurrents induced in the photovoltaic component at different levels of resolution.

Of course, here again, the size of the slab is not limited to that of a cell, and other sizes of slabs can be envisaged. In a particular embodiment of the proposed technique, illustrated in relation to FIGS. 8 and 9, the matrix comprising a plurality of liquid crystal shutters is of dimensions substantially equivalent to the standard dimensions of a photovoltaic panel (for greater readability of these figures, the modulation element 23 is presented in a configuration where it is not yet placed on the photovoltaic panel). Such an embodiment has the advantage of making it possible to measure the quality of an entire photovoltaic panel at different resolutions, without it being necessary to physically move the modulation element 23, once the latter is placed on the panel. The selection of the ZM modulation zone and its displacement after each measurement are in fact managed in a purely software manner, via the control unit of the measurement device. Such a solution thus offers great flexibility of use. As shown in FIGS. 8 and 9, it makes it possible, for example, to easily adapt the shape of the modulation zone ZM to that of the photovoltaic cells of the photovoltaic panel tested (cells Cl, C2, ..., Cn of square shape of 8, or the cells C1′, C2′, ..., Cm′ in the form of a strip of FIG. 9), for the implementation of measurements at the resolution of the size of a cell. During the measurement, the shutters that are not part of the modulation zone are all frozen in the same constant state, for example, their exposure state (as shown in the example of FIG. 8), or their shutter state (as shown in the example of FIG. 9, such a configuration being particularly interesting in that it makes it possible to limit stray light).

In a particular embodiment of the implementation of the modulation element in the form of a matrix of liquid crystal shutters, an intermediate size of panel - between a standard size of photovoltaic cell and a standard size of photovoltaic panel - constitutes a good compromise between transportability of the modulation element and flexibility in terms of resolution.

It should also be noted that the previous examples - describing the possibility of carrying out measurements and obtaining maps at a resolution of the size of the cell, the half-cell, or the quarter-cell in particular - are given for purely illustrative and non-limiting purposes. More particularly, it goes without saying that the proposed technique advantageously allows measurements to be carried out at much higher resolutions, for example of the order of a few micrometers when the modulation element takes the form of a matrix of shutters at liquid crystals with shutters in this order of dimensions. It is thus possible to draw up high-resolution maps revealing valuable information on the electrically active defects of the photovoltaic component under test.

In a particular embodiment which can be combined with one or the other of the two main implementations previously described (superimposed grids or matrix of liquid crystal shutters), the modulation element 23 also comprises optical filtering means making it possible to filtering, according to its wavelength, the part of the light radiation (eg sunlight) which reaches the tested zone of the photovoltaic component, after having crossed the modulation zone of the modulation element. In other words, these filtering means make it possible to select the wavelength or wavelengths of the modulated light incident on the zone tested. In this way, the proposed technique also makes it possible to characterize the photovoltaic component tested in its thickness, the level of depth tested depending on the selected wavelength. The filtering means can take the form of one or more colored supports, optionally interchangeable or combinable, arranged above and/or below the superimposed grids or the matrix of liquid crystal shutters (depending on the implementation of the considered modulation element). Alternatively or additionally, they can also take the form of a dye directly diffused into the optically transparent portions of the grids (when these are made of an optically transparent material) or in the liquid crystals of the shutters (depending on the implementation of the modulation element considered).

According to another aspect, the proposed technique also relates to a method for measuring the quality of a photovoltaic component by means of a measuring device as previously described. More particularly, according to the proposed method, the photovoltaic component is tested "in situ" (i.e. directly on the place where it is installed and under operating conditions) and it is illuminated only with natural sunlight. The photovoltaic component is typically a photovoltaic panel. The proposed method, described in relation to FIG. 10 in a particular embodiment, comprises at least one iteration of the following steps: a step of positioning 101 of the modulation element of the measuring device directly in contact with a zone comprising at least one zone to be tested of said photovoltaic component; a step 103 of activating the alternation, at a predetermined frequency, of the modulation zone of the modulation element, between its exposed state and its shuttered state. a measurement step 104, by the measurement unit of said measurement device (connected beforehand to the photovoltaic component to be tested), of the intensity of the current induced in the photovoltaic component by natural sunlight modulated by the modulation zone.

In a particular embodiment, optionally, the method also comprises, prior to said activation step 103, when the modulation element of the measuring device takes the form of a matrix comprising a plurality of crystal shutters liquid crystals, a step 102 of selecting a set of adjacent liquid crystal shutters of said matrix (comprising at least one liquid crystal shutter) defining said modulation zone.

Claims

1. Device for measuring the quality of a photovoltaic component (CP), said device comprising: a modulation element (23) for modulating, at a predetermined frequency, light incident on at least part of said photovoltaic component , known as the tested zone; a unit (24) for measuring the intensity of the current induced in said photovoltaic component by said modulated incident light, said intensity being representative of the quality of the zone tested; said measuring device being characterized in that said modulation element takes the form of a plate adapted to be placed directly or mounted flush on said photovoltaic component (CP), said plate comprising at least one modulation zone configured to alternate periodically, at said predetermined frequency, between two states: an exposure state in which the modulation zone allows the passage of light through said plate, at the level of said modulation zone; a closed state in which the modulation zone blocks the passage of light through said plate, at the level of said modulation zone; said modulation zone extending substantially over the entire surface of said plate, said modulation zone being formed by superimposing two grids, a fixed grid (31) and a mobile grid (32), each of the two grids comprising a succession of optically transparent portions and opaque portions, said movable grid being configured so as to be movable between at least a first position, corresponding to said exposure state, in which the optically transparent portions of the two grids overlap at least partially, and at least a second position, corresponding to said closed state in which the opaque portions of any one of the two grids completely block the optically transparent portions of the other of the two grids.

2. Measuring device according to claim 1, characterized in that said plate has dimensions substantially equivalent to the standard dimensions of a photovoltaic cell of a photovoltaic panel.

3. Measuring device according to any one of claims 1 to 2, characterized in that said modulation element further comprises means for optical filtering of said incident light, as a function of the wavelength.

4. Method for measuring the quality of a photovoltaic component by means of a measuring device according to any one of claims 1 to 3, said photovoltaic component being illuminated only by natural sunlight, said method comprising at least an iteration of the following steps: a step of positioning the modulation element of said measuring device directly in contact with an area comprising at least one area to be tested of said photovoltaic component; a step of activating the alternation, at a predetermined frequency, of the modulation zone of said modulation element, between its exposure state and its shutter state. a step of measuring, by the measuring unit of said measuring device, the intensity of the current induced in the photovoltaic component by the natural light modulated by said modulation zone.