Method for testing at least one bypass diode in an equipment comprising at least one operating photovoltaic module

Abstract

A method of testing at least one bypass diode (4) in a photovoltaic system (100) comprising at least one photovoltaic module (1) in operation, said photovoltaic module (1) comprising at least one string (2) of photovoltaic cells (3) connected to a bypass diode (4) dedicated to the string (2), the method comprising: a. Shielding a portion of the cells (3) of the string (2), switching to a bypass mode by means of the diode (4), said switching causing an increase in temperature of the diode (4) when the diode (4) is in an operating state; b. Measuring at least one temperature of the diode (4); and c. Comparing the measured temperature with a threshold value to infer the state of the diode (4).

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic modules or solar panels, and in particular to a method for testing at least one bypass diode in a system comprising at least one operating photovoltaic module, and a device for implementing the method. Background Art

[0002] Bypass diodes are electronic components which, when placed in bypass of a photovoltaic cell string, allow limiting the loss of production of a photovoltaic module in the event of a cell failure.

[0003] The principle of use of these bypass diodes is described below.

[0004] In a PV module containing multiple PV cells, partially shaded cells result in current loss. For completely opaque objects, such as leaves, the drop in current output from the cell will be proportional to the surface area of ​​the shaded cell.

[0005] When a string of cells connected in series approaches a short circuit, the forward bias voltage of all cells will cause the shaded cell to reverse bias to operate as a receiver. When a large number of cells in series cause a reverse bias in the shaded cell, a "hot spot" phenomenon occurs, causing a large amount of power to be dissipated in the shaded cell. This large amount of power dissipation in the cell can cause a local hot spot that can destroy at least that cell and may interfere with the performance of the entire module.

[0006] The destructive effects of hot spots can be avoided by using bypass diodes. If a solar cell becomes reverse biased due to a current imbalance between multiple series connected cells, the bypass diode will become conductive, allowing current to flow through the external circuit containing the bypass diode.

[0007] In practice, it is too expensive and difficult to place a bypass diode for each cell. Therefore, bypass diodes are usually placed on the battery strings. Each string usually contains eighteen to twenty-six cells. Each module usually contains three battery strings and three bypass diodes associated with each battery string.

[0008] Diagnosing the health of bypass diodes is critical to maximizing PV module yield.

[0009] In fact, there are two failure modes of bypass diodes: short circuit and open circuit. In the first case, bypass diode failure associated with the failure of one or more PV cells due to shading, short circuit or other reasons can lead to loss of yield of the PV module. In the second case, open circuit failure can lead to total power loss of the panel in the worst case.

[0010] It is known to automatically characterize the operation of the bypass diode. In particular, known electrical detection methods use the intensity / voltage (I / V) curve of the power provided by the module. Another known technique includes digital detection through machine learning (fuzzy logic). A third known technique is statistical detection, using statistical hypothesis testing, also known as T-test.

[0011] These techniques are based on analyzing the yield curve of PV modules. This analysis is more complicated when performed on a module string when the I / V curves of multiple PV modules are combined.

[0012] Furthermore, when a bypass diode is defective and remains in pass-through mode, there is no guarantee that the defect will be detected because electrical inspections on solar installations are typically performed on the entire system.

[0013] Furthermore, when the bypass diode is defective and remains closed during operation, if there are no other defects in the PV module, the defect will not be detected because the PV module will operate normally. However, in the event of a defect or partial or permanent shading, the defective diode will not be able to perform its protective role, and the shaded PV cells in the module are at risk of reaching hundreds of degrees Celsius, which may jeopardize the integrity of the PV module or even cause a fire in extreme cases.

[0014] Furthermore, there is no technology that can fully test the operation of bypass diodes during operation of PV modules in a solar power plant or PV system. For example, an infrared camera on a drone or airplane could be used, but a diode held in open circuit mode would not be visible.

[0015] Therefore, there is a need to test at least one bypass diode in a system comprising at least one operating photovoltaic module. Summary of the invention

[0016] The present invention improves this situation.

[0017] The present invention proposes a method for testing at least one bypass diode in a photovoltaic system comprising at least one operating photovoltaic module, wherein the photovoltaic module comprises at least one string of photovoltaic cells connected to a bypass diode dedicated to the string, the method comprising:

[0018] a. shielding part of the battery of the string, thereby switching to bypass mode through the diode, when the diode is in operation, the switching causes the temperature of the diode to increase;

[0019] b. measuring at least one temperature of a diode; and

[0020] c. Compare the measured temperature to a threshold value to infer the state of the diode.

[0021] The "state of a diode" means whether it is at least operating. Therefore, the "operational state of a diode" may at least mean that the diode is operational and can be used in a module. In more detail, its operation may be characterized, for example, by precisely recording its temperature or temperature changes.

[0022] The concept of a "threshold value" is general. It may involve measuring the temperature of the diode at another time (e.g. prior to the moment of switching to bypass mode), or for example measuring the temperature of another element, such as the temperature of the photovoltaic module itself or of the cell string to which the measured diode is connected, or the temperature of an area associated with the diode, or a fixed temperature, such as the ambient temperature (e.g. 25°C).

[0023] If the diode is in operation, its activation will generate local heating, which will be detected by measuring the temperature and characterized by comparison with the threshold value.

[0024] If the diode is not in operation, no temperature change will be observed.

[0025] If the temperature of the diode is measured just before switching to bypass mode, i.e. the moment it becomes conductive, and if this temperature constitutes a threshold approximately equal to the ambient temperature, and no temperature change of the diode is observed after switching, then it can be concluded that the diode is defective and stuck in open circuit mode.

[0026] If the diode temperature measured after switching is compared with a threshold corresponding to the diode temperature measured before switching, and if this temperature constitutes a threshold higher than the ambient temperature and no temperature change of the diode is observed after switching, then it can be concluded that the diode is defective and stuck in short-circuit mode.

[0027] The temperature of a diode can be the temperature of the diode itself, the temperature of the battery string it is in, or even the temperature of the module it is in.

[0028] Detecting one or more defective diodes can prevent potential safety hazards and / or increase the power yield of the system when the system comprises a plurality of photovoltaic modules. In addition, other relevant defects, such as one or more defective photovoltaic cells, can also be detected using the method according to the invention, in particular by temperature measurement.

[0029] Step b is performed after step a.

[0030] The photovoltaic module preferably comprises cells selected from the group consisting of half cells, full cells, so-called "shingled" cells cut into five or six strips, and thin film cells, such as cadmium telluride (CdTe), based on copper, indium, gallium and selenium (CIGS), based on gallium arsenide GaAs, etc.

[0031] The system preferably comprises a plurality of photovoltaic modules arranged side by side, each photovoltaic module comprising a plurality of cell strings, each cell string comprising a plurality of cells and each connected to a bypass diode.

[0032] The features described in the following paragraphs may optionally be implemented individually or in combination with each other:

[0033] When the photovoltaic module comprises a plurality of cell strings and a plurality of diodes associated with the cell strings, switching to bypass mode may be caused by partial shading above the plurality of cell strings, in which case a plurality of diodes are activated simultaneously and their states may be tested simultaneously using the method according to the invention.

[0034] The method can be implemented on multiple adjacent photovoltaic modules. Step a can be implemented on multiple cell strings at the same time, or even on multiple photovoltaic modules according to the assembly configuration of the photovoltaic modules (called a stand), which can cause multiple cell strings in the same photovoltaic module to switch to bypass mode at the same time and / or multiple cell strings distributed on different photovoltaic modules, for example, arranged in pairs in parallel, to switch to bypass mode at the same time.

[0035] At least steps a and b are preferably implemented using a robot, in particular a cleaning robot for photovoltaic modules. For this purpose, the robot is preferably configured to be able to shield part of the cells. The robot preferably comprises a thermal sensor, in particular a thermal imager, for measuring at least one temperature of the diode. The robot is preferably fixed to the photovoltaic module or photovoltaic system and can be moved translationally relative thereto in the direction of advance.

[0036] According to this embodiment, the method may use a cleaning robot, such as a cleaning robot actually present on the system containing the photovoltaic module, to cover part of the cells, but alternatively, other robots or other devices, or dedicated devices, may be provided, in particular additional devices that are integral to the module or photovoltaic system and are able to move in translation relative thereto.

[0037] In the case of a cleaning robot, the latter can move over the photovoltaic modules to participate in the operation of the test diodes.

[0038] The advantage of using a cleaning robot is that the cleaning of the modules can be combined with the diode operation test, so the test does not significantly increase the maintenance costs.

[0039] Step b may be performed after a time interval after step a is performed, in particular after switching to bypass mode and / or within a time interval, the time interval being between 10 seconds and 80 seconds.

[0040] The robot can move at a selected speed over the photovoltaic system to allow measuring the temperature of the diode before and after switching to bypass mode, so as to be able to observe the temperature variations when the diode is in operation. In particular, the robot can move at a selected speed over the photovoltaic system to allow measuring the temperature of the diode before (threshold) and after switching to bypass mode, so as to be able to observe the temperature variations of the diode between these two moments when the diode is in operation.

[0041] Such a speed may be uniform throughout the robot path or may vary, and in particular, may be zero during a predetermined period of time at one or more predetermined positions of the robot.

[0042] The robot can move autonomously or be controlled remotely.

[0043] At the moment when one or more diodes are switched to bypass mode, the robot can be commanded to stay there for a period of time, depending on how quickly hot spots appear on the diodes, for example a period between 20 seconds and 80 seconds.

[0044] The measurement can be performed for a duration of more than 10 seconds, in particular more than 20 seconds, to allow sufficient time for the diode to heat up and for the heat generated by the diode to diffuse to the front side of the module, since the diode is usually arranged on the back side of the module.

[0045] In this method, the temperature can be measured in at least one diode-related area of ​​the photovoltaic module so that there is a reference temperature before and / or during the measurement of the diode temperature after activating the diode, thereby monitoring whether the photovoltaic module itself changes temperature due to changes in the light received during the measurement period.

[0046] The photovoltaic modules may be connected to an inverter or a microinverter. In this case, the switch to bypass mode may be caused by the inverter or microinverter, in particular when the maximum power produced by the string is less than the maximum power produced by the adjacent string of the same module or adjacent series-connected modules. In this case, the inverter or microinverter sets the electrical operating point of the system.

[0047] In fact, if the shading or defect occurs on a cell or a group of cells on the same cell string, the I / V curve will be deformed and the maximum power point formed by the product of voltage and current according to the formula P=U*I will change. If the shading or defect is significant, the maximum operating point is located at the maximum power generated by the adjacent cell string of the same module or adjacent series modules, and this also corresponds to the case where the diode is activated. It is this case caused by the shading of the trigger diode in order to be able to test it.

[0048] When microinverters are present, the microinverters may be optimized on a module-by-module basis such that the diode is triggered when the maximum power produced by the shaded string or group of strings is lower than the maximum power produced by an adjacent string or group of strings of the same module or adjacent modules connected in series.

[0049] When PV modules are connected to an inverter, multiple modules are connected to the inverter: the inverter can optimize all of these modules. In this case, even with low levels of shading, the condition that the maximum power produced by a shaded string is lower than the maximum power produced by adjacent strings of the same module or adjacent modules connected in series is usually met, because all adjacent modules are operating normally.

[0050] When implementing steps a and b of the method, the ambient light intensity is preferably greater than 200 W / m 2 , more preferably greater than 500W / m 2 , and preferably less than 1000W / m 2 Such conditions ensure that the photovoltaic module is in operation. When implementing steps a and b of the method, the ambient temperature is preferably less than or equal to 40°C. If the light intensity does not exceed 1000W / m 2 The threshold value is exceeded and the ambient temperature, i.e. the outdoor temperature, is less than 40°C, which ensures that the heat generated by the tested diode will not be masked by the heat of the operating module.

[0051] When the light is insufficient, especially when some cells are insufficiently illuminated, the method may include a step performed simultaneously with step a, namely artificially illuminating some cells, especially using a lighting system, to ensure the operation of the photovoltaic module.

[0052] The method may include, before the shielding step a, a further step of measuring the temperature of the surface of the photovoltaic module where the diode to be tested is located, to determine the initial temperature, which may be performed by a thermal sensor, in particular a thermal imager. This temperature may constitute the threshold value.

[0053] Step b can be carried out using a thermal sensor, in particular a thermal imager. The method therefore preferably comprises a preceding step of adjusting the thermal sensor, in particular a thermal imager, for example by testing the bypass diode before carrying out steps a and b.

[0054] The threshold value mentioned in step b of the method may correspond to measuring the temperature of the diode before switching to the bypass mode, in particular just before the switching.

[0055] The photovoltaic module may comprise a plurality of photovoltaic cell strings connected in series, each cell string being connected to a dedicated bypass diode. In this case, steps a and b are preferably implemented on all or part of the plurality of cell strings.

[0056] The cleaning robot has the primary function of cleaning the photovoltaic module. It is able to move on the photovoltaic module while being integral with the module. To implement the method, the robot is preferably equipped with a shielding system and a thermal sensor, in particular a thermal imager. The robot may also be equipped with a processing circuit for implementing step c, for example using a measurement processing algorithm to compare the temperature measurement with the threshold value to determine the operating state of the diode under test. Such a processing circuit may also be located outside the robot, with which the robot is able to exchange information.

[0057] Preferably, step a is implemented so as to shade only a portion of the cells of a given cell string, while the other portion of the cells of the cell string remain illuminated either by ambient light or by an artificial lighting system.

[0058] The method may include, before performing step a, a step of optimizing the arrangement of the shading system for performing step a to trigger the relevant diodes. This may allow the shading system and its arrangement to be adjusted according to the configuration of the photovoltaic system and / or the type of cells in the module.

[0059] Step a can be implemented so that the photovoltaic module is symmetrically shaded between the cell strings and / or within the same cell string. This embodiment can include using two opaque parts of the shading system to symmetrically shade the cells of the cell string, for example, the cells in the central part are not shaded, especially arranged between the two opaque parts. The unshaded part of the cell can be covered by a transparent part of the shading system or a part with an opening, especially when the two opaque parts are connected. This embodiment is particularly suitable for half-cell photovoltaic modules with two series-connected cell strings and a shared protection diode.

[0060] The method may include a step of calibrating the shielding before performing step a. Such a step may include adjusting the shielding so that the maximum power of the shielded module is consistent with the activation of the diode. Such a step may be performed using a shielding system adapted to the module and the recording of the I / V curve.

[0061] The temperature measurement in step b can be performed by an operator. For example, the operator can perform infrared thermographic measurements on the back of the module holder as the robot passes over the module. This is particularly applicable to small photovoltaic systems.

[0062] According to other aspects, in combination with all or part of the above, a device for implementing the above method is proposed, including:

[0063] an item of equipment, in particular autonomous or remotely controlled, preferably integral to the photovoltaic system and movable, in particular translatable relative to the system, which item of equipment is opaque so as to at least partially shade some of the cells of at least one string of cells of at least one photovoltaic module in the system,

[0064] - a thermal sensor to measure the temperature of the diode, and

[0065] - Processing circuitry for comparing the temperature of the diode with a threshold value and inferring the state of the diode from the comparison.

[0066] According to other aspects, in combination with all or part of the above, there is provided a device component of the apparatus as described above, including a robot, in particular a cleaning robot for photovoltaic modules.

[0067] In this case, the robot may comprise at least one thermal imaging camera and at least one shielding system consisting of at least one flap attached to the robot or consisting of the robot itself.

[0068] The shielding system may include transparent and / or open portions to allow light to illuminate the portion of the photovoltaic cell associated with the diode to be tested.

[0069] The shielding system may comprise one or more baffles which are composed of several, in particular two, opaque parts connected by transparent parts and are, for example, arranged symmetrically. In this case, the transparent part may comprise an opening and at least two arms connecting the opaque parts in a particular embodiment.

[0070] The shielding system may be detachable from the robot and / or movable relative to the robot.

[0071] The baffle of the shielding system can be composed of a film or plate that is opaque to light. When implementing step a of this method, it can be arranged in front of the robot, at the back or on one side or more sides.

[0072] Particularly where the robot itself provides shading, the apparatus may include an integrated and controllable lighting system to illuminate portions of the cells associated with the diode to be tested. This may avoid completely shading any cell string of the diode to be tested, allowing for portions to be illuminated and portions to be shaded.

[0073] The robot may comprise an arm to which a thermal sensor, in particular a thermal imager, is attached so as to be able to access the back side of the modules housing the diodes, in particular when the ambient temperature is high and the sun significantly heats the photovoltaic modules, in which case the heat of the modules may prevent the detection of overheated diodes.

[0074] The robot may include an integrated lighting system for illuminating part of the battery and activating the diode, particularly when ambient light is insufficient.

[0075] In particular, when the photovoltaic cells are thin film cells, the shading system may be configured according to the arrangement of the cells to ensure activation conditions for the diodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Other features, details and advantages will become apparent upon reading the following detailed description and analyzing the accompanying drawings, in which:

[0077] Figure 1 An example of a photovoltaic module in which the method of the invention can be implemented is schematically shown.

[0078] Figure 2 are intensity vs. voltage curves that are recorded for a photovoltaic module depending on the shaded area of ​​the module.

[0079] Figure 3 Schematic diagram of a photovoltaic module with 25% shaded cells in a string, which enables to obtain Figure 2 One of the curves in .

[0080] Figure 4 Schematic diagram of a photovoltaic module with 50% shaded cells in a string, which enables to obtain Figure 2 Another curve in .

[0081] Figure 5 Schematic diagram of a photovoltaic module with 75% shaded cells in a string, which enables to obtain Figure 2 Another curve in .

[0082] Figure 6 It is used to illustrate the Figure 5 A graph of intensity versus voltage recorded by the module.

[0083] Figure 7 It is used to illustrate the Figure 5 A graph of power and voltage recorded by the module.

[0084] Figure 8 A top view of a photovoltaic module on which a method according to an embodiment of the present invention can be implemented is schematically shown.

[0085] Fig. 9 Schematically shows Figure 8 FIG. 4 is a cross-sectional view of a photovoltaic module during implementation of the method.

[0086] Fig.10 is a photograph of a photovoltaic system implementing the method of the present invention.

[0087] Fig.11 is an exemplary top view of a photovoltaic module according to one embodiment of the present method.

[0088] Fig.12 is an exemplary top view of a photovoltaic module according to one embodiment of the present method.

[0089] Fig.13 is an exemplary top view of a photovoltaic module according to one embodiment of the present method.

[0090] Fig.14 is an exemplary top view of a photovoltaic module according to one embodiment of the present method.

[0091] Fig.15 is an exemplary top view of a photovoltaic module according to one embodiment of the present method.

[0092] Fig.16 is an exemplary top view of a photovoltaic module according to one embodiment of the present method.

[0093] Fig.17 is an exemplary top view of a photovoltaic module according to one embodiment of the present method.

[0094] Fig.18 After the robot moves forward Fig.17 Example top view of a photovoltaic module.

[0095] Fig.19 is an exemplary top view of a photovoltaic module according to one embodiment of the present method.

[0096] Fig. 20 After the robot moves forward Fig.19 Example top view of a photovoltaic module.

[0097] Fig.21 is an exemplary top view of a photovoltaic module according to one embodiment of the present method.

[0098] Fig. 22 After the robot moves forward Fig.21 Example top view of a photovoltaic module.

[0099] Fig.23 is an exemplary top view of a photovoltaic module according to one embodiment of the present method.

[0100] Fig.24 is an exemplary top view of a photovoltaic module according to one embodiment of the present method.

[0101] Fig.25 is an exemplary top view of a photovoltaic module according to one embodiment of the present method.

[0102] Fig.26 A schematic perspective view of an example of an apparatus for carrying out the method according to the invention in the form of an embodiment of a cleaning robot.

[0103] Fig. 27 It is to deploy the occlusion system Fig.26 A perspective schematic diagram of the device in FIG. DETAILED DESCRIPTION

[0104] Reference Figure 1 In this figure, a photovoltaic module 1 is schematically shown in a top view, which comprises two cell strings 2, each cell string 2 comprising a plurality of photovoltaic cells 3, and in this example each cell string 2 comprises eighteen cells 3. The cells 3 are connected to each other in series. Figure 1 The battery string 2 shown contains a shaded battery 3a. Each battery string 2 is associated with a bypass diode 4, so that when one or more batteries 3 of the battery string 2 are shaded, the current no longer flows through the battery 3 of the battery string 2, but flows through the diode 4. The diode 4 is thus activated and becomes conductive. A bypass is established.

[0105] In this example, module 1 is connected to microinverter 8. When battery string 2 is not shaded, Figure 2 As shown in the curves C0 and C1 , the micro inverter 8 selects the maximum power point P1 of one battery string 2 and the maximum power point P2 of the adjacent battery string.

[0106] On the other hand, Figures 3 to 5 As shown in FIG. 1 , if part of the battery string 2 is shaded by the shade system 5, the power will be as follows: Figure 2 The decrease shown by the curve C2 to C4 in FIG. Figure 3 As shown, P2* represents the maximum power point obtained when 25% of the surface area of ​​the battery 3 of a battery string 2 is shaded. Figure 4 As shown, P2** represents the maximum power point obtained when 50% of the surface area of ​​the battery 3 of a battery string 2 is shaded. Figure 5 As shown, P2*** represents the maximum power point obtained when 75% of the surface area of ​​the battery 3 of one battery string 2 is shaded.

[0107] Figure 6 and Figure 7 The curves shown in Figure 5 The I / V curves and Figure 5 The power (watts) and voltage (volts) curves for the same module in Figure 2.

[0108] The micro inverter 8 is programmed to trigger switching to bypass mode, ie, activate the bypass diode 4 when P1>P2, where P2 can be P2, P2*, P2** or P2*** according to the shading condition of the battery string 2.

[0109] The method of the present invention utilizes these characteristics to detect defective diodes.

[0110] In fact, the method of the present invention is a method for testing at least one bypass diode 4 in a photovoltaic system 100 comprising at least one operating photovoltaic module 1, the photovoltaic module 1 being at least one cell string 2 comprising photovoltaic cells 3, in one case three cell strings 2, each comprising twenty photovoltaic cells 3, each cell string 2 being connected to its dedicated bypass diode 4.

[0111] like Figure 8 As shown, the method comprises a step of shielding at least some of the cells 3 of the battery string 2 using a shielding system 5, in this case comprising two opaque shutters 9, until this causes a switch to bypass mode via a dedicated diode 4 of the battery string 2. If the diode 4 is in an operational state, the switch causes an increase in the temperature of the diode 4. This bypass switch can be triggered by the microinverter 8. The method also comprises a step of measuring at least one temperature of the diode 4 using a thermal sensor 11, and a step of comparing the measured temperature with a threshold value using a processing circuit 20 to infer the state of the diode 4, i.e. whether the diode 4 is in an operational state or is defective.

[0112] like Fig. 9 As shown, in this example, the diode 4 is located on the back side 7 of the photovoltaic module 1. Figure 8 Visible in the figure is the front side 6.

[0113] The microinverter 8 performs module-by-module optimization so that the diode 4 is triggered when the maximum power generated by the shaded cell string 2 is lower than the maximum power generated by the adjacent cell string 2 of the same module 1 or an adjacent module 1 connected in series.

[0114] exist Figure 8 In the example shown in FIG. 1 , the system 100 includes a photovoltaic module 1 .

[0115] In this example, the ambient light intensity is greater than 200 W / m, and the method is implemented at a light intensity less than 1000 W / m 2 Such conditions ensure that the photovoltaic module 1 is in operating condition. The ambient temperature during the implementation of the method is preferably less than or equal to 40°C.

[0116] If the diode 4 is in operation, its activation will result in local heating, which will be detected by temperature measurement and characterized by comparison with a threshold value.

[0117] If the diode is not in operation, no temperature changes will be detected there.

[0118] If the temperature of diode 4 is measured at the moment before switching to bypass mode, i.e. at the moment when it becomes conductive, and if this temperature constitutes a threshold value substantially equal to the ambient temperature and no temperature change of diode 4 is detected after switching, it can be concluded that diode 4 is defective and is stuck in open circuit mode.

[0119] If the temperature of diode 4 measured after switching to bypass mode is compared with a threshold value corresponding to the temperature of diode 4 measured before switching, and if the threshold value constituted by this temperature is higher than the ambient temperature and no temperature change of the diode is detected after switching, then it can be concluded that the diode is defective and stuck in short-circuit mode.

[0120] Detection of one or more defective diodes 4 can help prevent potential safety hazards and / or improve the power production of a system comprising a plurality of photovoltaic modules, such as a solar power plant. In addition, other relevant defects, such as one or more defective photovoltaic cells, can also be detected using the method of the present invention, in particular by temperature measurement.

[0121] The method can be implemented using an automated or remotely controlled piece of equipment that is configured to be integrated with the photovoltaic system 100 and to move or be moved relative to the module 1. The piece of equipment can be a robot, in this case a cleaning robot 10 for the photovoltaic module 1, Fig.10 An example is given in FIG. Such a cleaning robot 10, which is known per se, is used for regular cleaning such as Fig.10 The photovoltaic module 1 of the photovoltaic system 100 comprising a plurality of photovoltaic modules 1. The cleaning robot 10 can be advantageously used to implement the method of the present invention. This can avoid a significant increase in maintenance costs, since the cleaning robot 10 is already used for regular maintenance of the photovoltaic module 1.

[0122] exist Figures 11 to 16 In the example shown, the photovoltaic system 100 comprises a plurality of photovoltaic modules 1 arranged side by side, from bottom to top and in a transverse arrangement. The robot 10 covers the surface of the system 100, from bottom to top. The robot 10 moves in the advancing direction A indicated by the arrow in these figures. A shielding system 5 is arranged at the rear of the cleaning robot 10 and fixed thereon, for implementing the step of shielding at least part of the cells 3 of one or more cell strings 2 with the aid of the shielding system 5, until the dedicated diode 4 of this or these cell strings 2 is triggered to switch to the bypass mode. The cleaning robot 10 is also equipped with a thermal sensor, in this case a thermal imager 11, which is only used when Fig.11 Schematically shown in Figures 11 to 16 exists in all embodiments of .

[0123] Such a thermal imager 11 can implement a step of measuring at least one temperature of the diode 4. The robot 10 is also configured to compare the measured temperature with a threshold value in order to infer the state of the diode or diodes 4, i.e. whether the diode 4 is in a functional state or defective. Alternatively, the robot 10 is connected to a processing circuit that allows comparing the measured temperature with a threshold value in order to infer the state of the diode or diodes 4.

[0124] More specifically, in Fig.11 In the embodiment shown, the system 100 comprises three photovoltaic modules 1 in a direction perpendicular to the advancing direction A. Each photovoltaic module 1 comprises three cell strings 2, each string having twenty cells 3, and each string further comprising a bypass diode 4. The robot 10 comprises a shielding system 5, which comprises three baffles 9, each comprising an opaque portion 12 and a transparent portion 13, the opaque portion 12 being divided into two parts, one on each side of the transparent portion 13. In this example, the shielding formed by the opaque portion 12 is symmetrical, which can allow more precise control of the activation of the diode. Each baffle 9 covers the central cell string 2c of the photovoltaic module 1, wherein the opaque portion 12 shields a portion of the central cell string 2c until a switch to bypass mode is triggered, thereby activating the dedicated diode 4c of the central cell string 2c. The speed of the robot 10 is adjusted to allow such a switch, for example, stopping at the position shown in the figure for more than 10 seconds, for example more than 20 seconds, and less than 80 seconds. This can activate the three diodes 4c of these central cell strings 2c of the module 1.

[0125] Fig.12 The implementation method and Fig.11 The difference is that the transparent part 13 comprises an opening 14 formed between two transparent arms 16 connecting the two opaque parts 12. The opening 14 can facilitate the detection of the heating of the diode 4c.

[0126] exist Fig.13 In the example of , the number of photovoltaic modules 1 of the system 100 in a direction perpendicular to the advancing direction A is equal to four. In addition, the shielding system 5 comprises two baffles 9, each comprising an opaque portion 12 and a transparent portion 13, the opaque portion 12 being divided into two parts, one on each side of the transparent portion 13. Each opaque portion 12 covers two parts of adjacent cell strings 2 belonging to two different and adjacent modules 1. Therefore, the two baffles 9 allow four diodes 4 belonging to four different modules 1 to be activated simultaneously. In this example, the shielding formed by the opaque portions 12 is symmetrical, which can allow more precise control of the activation of the diodes 4.

[0127] Fig.14 The implementation method and Fig.13The difference is that the transparent part 13 comprises two openings 14 formed between two transparent arms 16 connecting the two opaque parts 12. The openings 14 can help to detect the heating of the associated diode 4.

[0128] exist Fig.15 In the embodiment of Fig.13 In the system 100 of 14, the shielding system 5 includes three baffles 9, each partially covering two adjacent cell strings 2. Two baffles 9 each cover two adjacent cell strings 2 of the same module 1, causing two diodes 4 of the same module 1 to switch to bypass mode, while the middle baffle 9 covers two adjacent cell strings 2 of two different modules 1, causing one diode 4 of each module 1 to switch to bypass mode.

[0129] Fig.16 The implementation method and Fig.15 100 in that it comprises a shielding system 5 covering the entire width of the robot 10 and the system 100, this width being perpendicular to the direction of advancement A. The shielding system 5 comprises a baffle 9 comprising opaque parts 12 symmetrically surrounding a central transparent part 13. Thus, all diodes 4 of all modules 1 of the system 100 arranged from bottom to top are activated simultaneously and can be tested simultaneously.

[0130] In such Figures 17 to 22 In the illustrated embodiment, the system 100 comprises a series of photovoltaic modules 1 arranged side by side along the advancing direction A of the robot 10. Each module 1 comprises three battery strings 2, and each battery string comprises twenty batteries 3. Figures 11 to 16 In the embodiment of the present invention, the battery strings 2 extend in parallel along the advancing direction A. Figures 17 to 22 In the embodiment of FIG. 1 , the battery string 2 extends perpendicular to the advancing direction A.

[0131] About these Figures 17 to 22 In the example of the robot 10 itself is the shielding system 5, which is not deployed externally to the robot 10, but is part of the robot. In addition, the cleaning robot 10 comprises a lighting system 15 to illuminate the shielded battery part and participate in triggering the diode 4. The lighting system 15 can be used to compensate for insufficient light. In this case, it is used to compensate for the shielding formed by the robot 10 on the area of ​​the battery string 2 to activate the diode 4.

[0132] exist Fig.17 In the example shown, the shielding system 5 comprises two opaque baffles 9, arranged symmetrically around the diode 4 of one string 2 of the module 1. The part of the string 2 not intended to be shielded is illuminated by the lighting system 15 to ensure activation of the dedicated diode 4 of the string 2.

[0133] Fig.18 Shown Fig.17 The robot 10 moves to the next battery string 2 of the adjacent module 1 to switch the bypass mode through the dedicated diode 4 of this battery string 2 so that its status can be checked.

[0134] exist Fig.19 and 20 In the embodiment of the invention, two adjacent strings 2 of the module 1 are the object of implementation of the method of the invention, the robot 10 forms a shielding system 5 that symmetrically covers two parts of the two strings 2, which are located on both sides of the central part of these strings 2, which is illuminated by the lighting system 15. Thus, the two dedicated diodes 4 of the two strings 2 can be tested.

[0135] Fig. 20 Shows how Fig.19 The cleaning robot 10 moves to the other two battery strings 2 of the adjacent module 1 to switch to the bypass mode through the dedicated diodes 4 of these other two battery strings 2 so that their status can be checked.

[0136] exist Fig.21 and 22 In the embodiment of the invention, three battery strings 2 of the same module 1 are the object of implementation of the method of the invention, and the robot 10 forms a shielding system 5 that symmetrically covers two parts of these three battery strings 2, which are located on both sides of the central part of these battery strings 2, and the central part is illuminated by the lighting system 15. Therefore, three diodes 4 of the module 1 are tested, which diodes 4 are dedicated diodes for these battery strings 2 of the module 1.

[0137] Fig. 22 Shown Fig.21 The robot 10 moves to the other three battery strings 2 of the adjacent module 1 to switch the bypass mode through the dedicated diodes 4 of these other three battery strings 2 of the adjacent module 1 so that their status can be checked.

[0138] exist Fig.23 , 24 In the embodiment shown in Figures 2 and 3, the robot 10 does not extend to the entire width of the module 1 of the system 100 in the width perpendicular to the direction of advancement A. Further, the system 100 comprises a single module 1 in this width, such as Figures 17 to 22 In addition, the shielding system 5 comprises two shielding plates 9 , each comprising only one opaque portion 12 , which are deployed at the rear of the robot 10 to shield a portion of the battery 3 .

[0139] exist Fig.23 In the embodiment of the present invention, part of the cells 3 of the cell string 2 , in particular half thereof, is shielded to trigger the switch to the bypass mode, thereby activating the dedicated diode 4 of the cell string 2 .

[0140] exist Fig.24 In an embodiment, parts of the cells 3 of two adjacent cell strings 2 , in particular half thereof, are shaded to trigger a switch to bypass mode, thereby activating the two diodes 4 associated with these cell strings 2 .

[0141] Finally, in Fig.25 In the embodiment of , parts of the cells 3 of three cell strings 2 , ie all cell strings 2 of the module 1 , in this example, are shaded to trigger the switch to the bypass mode, thereby activating the three diodes 4 of the module 1 .

[0142] Activating the diodes 4 is the first step before measuring the temperature of the diode or diodes 4 in order to be able to compare it / them with a threshold value and to conclude whether the diode 4 is in an operational state.

[0143] The temperature measurement step is preferably performed by a robot 10, which is equipped with at least one thermal sensor, in particular a thermal imager 11. Such a thermal imager 11 is capable of measuring the temperature of the diode 4 or diodes 4, for example before and / or after switching to bypass mode, and / or the module surface, the ambient temperature, etc.

[0144] The step of comparing the measured temperature with a threshold value and deducing the state of the diode 4 may be performed by the robot 10 itself, if it is equipped with a processing circuit, or by an external processing circuit that communicates with the robot 10 to exchange information.

[0145] exist Fig.26 and 27 In the embodiment shown, the cleaning robot 10 comprises a shielding system 5, which consists of a baffle 9 rotatable relative to the body 18 of the robot 10 so as to Fig.26 The folded position shown moves to Fig. 27 In the folded position, the shielding system 5 cannot shield part of the battery 3 , whereas in the unfolded position, when the robot 10 is attached to the photovoltaic system 100 and / or at least one photovoltaic module 1 , the shielding system 5 can cover part of the battery 3 .

[0146] Of course, the invention is not limited to the examples that have just been described.

[0147] Robots can be autonomous or remotely controlled.

[0148] When there are multiple photovoltaic modules 1, their management can be performed by an inverter instead of a microinverter. Multiple modules are thus connected to an inverter. The inverter can optimize all of these modules. In this case, even if the degree of shading is low, the condition that the maximum power produced by a shaded string is less than the maximum power produced by adjacent strings of the same module or adjacent modules connected in series is generally met, because all adjacent modules are operating normally.

[0149] Any robot or piece of equipment, whether autonomous or remotely controlled, other than the cleaning robot 10, whether dedicated or non-dedicated, may be used in the present invention.

[0150] The method may include, before the shielding step, a step of measuring the temperature of the surface 6 of the photovoltaic module 1 at the location of the diode 4 to be tested, to determine the initial temperature, which may be done by a thermal sensor, in particular a thermal imager 11. This temperature may constitute the threshold value.

[0151] The method may include a step of calibrating the shading before the shading. Such a step may include adjusting the shading so that the maximum power of the shaded module 1 coincides with the activation of the diode 4. Such a step may be done using a shading system 5 adapted to the module 1 and the recording of the I / V curve.

[0152] In the method, the temperature of at least one area of ​​the photovoltaic module 1 associated with the diode 4 can be measured, for example as a threshold value in order to have a reference value before activating the diode 4 and / or while measuring the temperature of the diode 4, after the diode has been activated, in order to monitor whether the photovoltaic module 1 itself changes temperature due to changes in the light received during the measurement period.

[0153] The step of measuring the temperature of the diode 4 after shielding can be implemented using a thermal sensor, in particular a thermal imager. The method therefore preferably includes a preceding step of adjusting the thermal sensor, in particular a thermal imager, such as testing the bypass diode 4 before shielding and measuring the temperature of the diode 4.

Claims

1. A method for testing at least one bypass diode (4) in a photovoltaic system (100) comprising at least one operating photovoltaic module (1), wherein the photovoltaic module (1) comprises at least one string (2) of photovoltaic cells (3) connected to a bypass diode (4) dedicated to the string (2), the method comprising: include: a. shielding part of the battery (3) of the string (2), thereby switching to the bypass mode through the diode (4), when the diode (4) is in operation, the switching causes the temperature of the diode (4) to increase; b. measuring at least one temperature of a diode (4); and c. Compare the measured temperature with a threshold value to infer the state of the diode (4).

2. The method according to claim 1, It is characterized in that At least steps a and b are implemented using a robot (10), in particular a photovoltaic module cleaning robot, the robot (10) being configured to shield the portion of cells (3) and comprising a thermal sensor, in particular a thermal imager (11), for measuring at least one temperature of the diode (4).

3. The method according to claim 2, It is characterized in that The robot (10) moves over the photovoltaic system (100) at a speed selected to allow the temperature of the diode (4) to be measured before and after switching to bypass mode, thereby being able to observe the temperature changes of the diode (4) when the diode is in operation.

4. A method according to any preceding claim, It is characterized in that The photovoltaic module (1) is connected to an inverter or a micro-inverter (8), and the switching to bypass mode is caused by the inverter or the micro-inverter (8), in particular when the maximum power generated by the string (2) is less than the maximum power of an adjacent string (2) of the same module (1) or adjacent serially connected modules (1).

5. A method according to any preceding claim, It is characterized in that When implementing steps a and b of the method, the ambient lighting is greater than 200 W / m 2 , and preferably less than 1000W / m 2 , and when implementing steps a and b of the method, the ambient temperature is preferably less than or equal to 40°C.

6. A method according to any preceding claim, It is characterized in that Step b is implemented using a thermal sensor, in particular a thermal imager (11), the method also comprising a preceding step of adjusting the thermal sensor, in particular a thermal imager (11), in particular testing the bypass diode (4) before implementing steps a and b.

7. A method according to any preceding claim, It is characterized in that The threshold value corresponds to the temperature of the diode (4) measured before switching to bypass mode.

8. A method according to any of the preceding claims, the photovoltaic module (1) comprising a plurality of strings (2) of photovoltaic cells (3) connected in series, each string (2) being connected to its dedicated bypass diode (4), wherein steps a and b are implemented on all or part of the plurality of strings (2) of cells (3).

9. An apparatus for implementing the method according to any one of the preceding claims, comprising at least: - An opaque device for shielding a portion of cells (3) of at least one string (2) of at least one photovoltaic module (1) in a photovoltaic system (100), - a thermal sensor for measuring the temperature of the diode (4), and - Processing circuitry is provided for comparing the temperature of the diode (4) with a threshold value and inferring the state of the diode (4) from the comparison.

10. Equipment components of the device according to claim 9, comprising a robot (10), in particular a cleaning robot for photovoltaic modules (1).

11. The device according to claim 10, It is characterized in that The robot (10) comprises at least one thermal imaging camera (11) and at least one shielding system (5) consisting of at least one shielding plate (9) connected to the robot (10) or consisting of the robot (10) itself.

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