Photovoltaic module cell abnormality detection method

Abstract

The application discloses a photovoltaic module cell abnormality detection method, and belongs to the technical field of photovoltaic module testing. The method mainly comprises the following steps: after the light source irradiance, the ambient temperature and the loop current between the positive and negative electrodes of the to-be-tested photovoltaic module are controlled to make the test conditions reach preset test conditions, the cell pieces forming a cell string in the to-be-tested photovoltaic module are shaded according to a preset shading ratio, the temperature of the cell pieces not shaded in the cell string is detected to obtain the temperature difference between the unshaded cell pieces, and the temperature difference is compared with a preset threshold value to determine whether a cell piece leakage abnormality occurs. By adopting the method, whether the photovoltaic module cell pieces have the abnormality of high leakage current can be quickly and accurately detected.

Description

Technical Field

[0001] This application relates to the field of photovoltaic module testing technology, and specifically to a method for detecting abnormalities in photovoltaic module cells. Background Technology

[0002] In recent years, the global photovoltaic market has flourished, with the installed capacity of photovoltaic power generation systems increasing year by year. Among these, photovoltaic modules are the main products of photovoltaic power generation. Photovoltaic modules need to operate for extended periods in complex and variable outdoor environments, making their safety and reliability particularly important. Among these, the safety of the solar cells that make up the photovoltaic modules is the core of the safety of photovoltaic products.

[0003] Currently, the industry relies on EL (electroluminescence) testing before a solar cell makes up a photovoltaic module to determine if there are any abnormalities. According to the principle of electroluminescence, when a current is applied to the module in the forward direction, the cell emits light under the influence of the current. By capturing images of the cell's light emission with a camera, the surface of the cell can be observed for abnormalities such as microcracks, poor soldering, or broken grids. This testing method can only detect physical defects in the cell, but it cannot detect abnormalities such as excessive leakage current in the cell itself. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this application proposes a method for detecting abnormalities in solar cells, which solves the technical problem of quickly and accurately detecting whether there are abnormalities such as high leakage current in solar cells of photovoltaic modules.

[0005] This application provides a method for detecting abnormalities in photovoltaic module cells, including:

[0006] Step S1: Control the light source irradiance, ambient temperature and loop current between the positive and negative electrodes of the photovoltaic module under test so that the test conditions reach the preset test conditions. The photovoltaic module under test includes at least one battery cell, and the battery cell includes at least one set of battery cells connected in series to form a battery string.

[0007] Step S2: The solar cells forming a battery string in the photovoltaic module under test are shaded according to a preset shading ratio, and the temperature of the unshaded solar cells in the battery string is detected to obtain the temperature difference between the unshaded solar cells.

[0008] Step S3: Compare the temperature difference with a preset threshold to determine whether a cell leakage abnormality has occurred.

[0009] In some technical solutions, step S1 includes: connecting the photovoltaic module under test to the testing device, and controlling the light source irradiance, ambient temperature and loop current between the positive and negative electrodes of the photovoltaic module under test based on the testing device so that the testing conditions reach the preset testing conditions.

[0010] The testing device is a box structure, and a light source, a temperature monitoring device, a current monitoring device, and a connection device are installed inside the box structure.

[0011] The above-mentioned connection of the photovoltaic module under test to the testing device includes: connecting the testing device to the positive and negative terminals of the photovoltaic module under test through the connection device.

[0012] The above-mentioned control of the light source irradiance, ambient temperature, and loop current between the positive and negative electrodes of the photovoltaic module under test based on the testing device to achieve the preset test conditions includes: under the action of the light source, when the temperature monitoring device detects that the light source irradiance and ambient temperature of the battery string of the photovoltaic module under test have reached the standard test conditions, and when the current monitoring device detects that the loop current between the positive and negative electrodes of the photovoltaic module under test has reached the maximum, it indicates that the test conditions have reached the preset test conditions.

[0013] Furthermore, a variable resistor is also provided inside the aforementioned housing structure, the variable resistor being connected between the positive and negative terminals of the photovoltaic module under test; correspondingly, step S1 further includes: maximizing the loop current between the positive and negative terminals of the photovoltaic module under test by short-circuiting the positive and negative terminals, or maximizing the loop current between the positive and negative terminals of the photovoltaic module under test by adjusting the variable resistor.

[0014] In some technical solutions, the photovoltaic module includes n sets of battery strings, where n ≥ 1, and step S2 specifically includes:

[0015] The area occupied by at least half of the battery cells in each of the n battery strings is defined as the light-shielding area, and the area occupied by the remaining battery cells is defined as the non-light-shielding area. After the light-shielding area is blocked from light for a preset time, the temperature of at least half of the battery cells in the n battery strings is detected, and the temperature difference between the individual battery cells is obtained based on the detected temperature of each battery cell.

[0016] The shaded area and the non-shaded area are interchanged to detect the temperature of the remaining number of battery cells in the n sets of battery strings, and the temperature difference between the individual battery cells is obtained based on the detected temperature of each battery cell.

[0017] In some technical solutions, the photovoltaic module includes 2n sets of cell strings, where n≥1, and step S2 specifically includes:

[0018] Two battery strings are selected from the 2n battery strings each time to perform the following steps S21 and S22 until all battery strings have been detected.

[0019] Step S21: The area occupied by at least half of the battery cells in the two sets of battery strings is determined as the light-shielding area, and the area occupied by the remaining battery cells is determined as the non-light-shielding area. After the light-shielding area is blocked for a preset time, the temperature of at least half of the battery cells in the two sets of battery strings is detected, and the temperature difference between the individual battery cells is obtained based on the detected temperature of each battery cell.

[0020] Step S22: For each of the two sets of battery strings selected, the shaded area and the non-shaded area are interchanged to detect the temperature of the remaining number of battery cells in the two sets of battery strings, and the temperature difference between the individual battery cells is obtained based on the detected temperature of each battery cell.

[0021] Furthermore, the preset duration ranges from 5 to 10 minutes.

[0022] The above-mentioned light blocking of the light-blocking area specifically includes using a light-blocking device to block the light in the light-blocking area.

[0023] Before exchanging the light-shielding area and the non-light-shielding area, the process includes: removing the light-shielding device from the light-shielding area and waiting for 10 minutes before using the light-shielding device to block light from the newly determined light-shielding area.

[0024] The above-described technical solutions of this application have at least one or more of the following beneficial effects: After controlling the light source irradiance, ambient temperature, and loop current between the positive and negative electrodes of the photovoltaic module under test to achieve preset test conditions, the solar cells forming a battery string in the photovoltaic module under test are shaded according to a preset shading ratio. Temperature detection is performed on the unshaded cells in the battery string to obtain the temperature difference between the unshaded cells. The temperature difference is compared with a preset threshold to determine whether a cell leakage abnormality has occurred. The photovoltaic module cell anomaly detection method provided in this application is applicable to both laboratory testing and outdoor photovoltaic module testing. This method can quickly and accurately detect whether photovoltaic module cells have abnormally high leakage current and effectively detect cells that may have hot spot risks, which can greatly meet the safety testing requirements of photovoltaic modules. Attached Figure Description

[0025] The disclosure of this application will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. Furthermore, similar numbers in the drawings are used to denote similar components, wherein:

[0026] Figure 1 This is a schematic flowchart of the main steps of a photovoltaic module cell anomaly detection method according to an embodiment of this application;

[0027] Figure 2 This is a schematic flowchart of the main steps of another photovoltaic module cell anomaly detection method according to an embodiment of this application;

[0028] Figure 3 This is a schematic diagram of the composition structure of a testing device according to an embodiment of this application;

[0029] Figure 4 This is a schematic diagram of the composition structure of another testing device according to an embodiment of this application;

[0030] Figure 5 This is a schematic diagram of an application scenario for anomaly detection of photovoltaic module cells based on a testing device, provided in an embodiment of this application.

[0031] Figure 6 This is a schematic diagram of another application scenario for anomaly detection of photovoltaic module cells based on a testing device, provided in an embodiment of this application. Detailed Implementation

[0032] Some embodiments of this application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of this application and are not intended to limit the scope of protection of this application.

[0033] In the description of this application, the term "A and / or B" means all possible combinations of A and B, such as only A, only B, or A and B. The terms "at least one A or B" or "at least one of A and B" have a similar meaning to "A and / or B" and may include only A, only B, or A and B. The singular terms "a" or "this" may also include plural forms.

[0034] The embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the embodiments described herein are for illustration and explanation only and are not intended to limit this application. Furthermore, the embodiments and features in the embodiments of this application can be combined with each other without conflict.

[0035] Practical applications show that photovoltaic (PV) modules with excessively high leakage current experience increased power consumption and higher temperatures when hot spots occur. Under long-term outdoor operation, the lifespan of these cells is significantly shortened, posing a substantial safety hazard to the PV module and the entire PV system. Therefore, detecting leakage current abnormalities in PV module cells is crucial for PV module safety testing. To address this, this application proposes a method for detecting abnormalities in PV module cells, enabling rapid and accurate detection of excessively high leakage current.

[0036] See appendix Figure 1 , Figure 1 This is a schematic flowchart illustrating the main steps of a photovoltaic module cell anomaly detection method according to an embodiment of this application. The method of this embodiment can quickly and accurately determine whether there is leakage anomaly in the cells of a photovoltaic module. Figure 1 As shown, the photovoltaic module cell anomaly detection method in this application embodiment mainly includes the following steps S1 to S3.

[0037] Step S1: Control the light source irradiance, ambient temperature, and loop current between the positive and negative electrodes of the photovoltaic module under test so that the test conditions meet the preset test conditions.

[0038] The photovoltaic module under test described in this embodiment includes at least one battery cell, and the battery cell includes at least one set of battery cells connected in series to form a battery string.

[0039] The preset test conditions in this embodiment can be defined in conjunction with the requirements of the actual application environment or the actual test standard. For example, the preset test conditions may specifically include: the test conditions meet the STC test conditions and the loop current between the positive and negative electrodes reaches its maximum. It should be understood that the full name of STC test conditions is Standard Test Conditions, which refers to the test conditions used by photovoltaic module manufacturers to rate and certify photovoltaic modules.

[0040] Step S2: The solar cells forming a battery string in the photovoltaic module under test are shaded according to a preset shading ratio, and the temperature of the unshaded solar cells in the battery string is detected to obtain the temperature difference between the unshaded solar cells.

[0041] In this embodiment, the preset shading ratio specifically refers to the ratio formed by the number of solar cells that need to be shaded and the number of solar cells that do not need to be shaded. In practical applications, this ratio can be determined first based on the number of cell strings or the number of solar cells forming the cell strings in the photovoltaic module under test. Then, the shading area is determined by combining the area occupied by the corresponding number of solar cells, and then the shading process is performed. For example, if the number of cell strings in the photovoltaic module is 6, and each cell string contains 8 solar cells, the preset shading ratio can be defined as 1 / 2, that is, the number of solar cells that need to be shaded each time is 24. Accordingly, this step can be specifically as follows: by shading 24 solar cells in the photovoltaic module under test, and by performing temperature detection on the remaining 24 unshaded solar cells to obtain the temperature difference between the 24 unshaded solar cells, the shading areas can be interchanged and the shading and detection can be performed in the same way to obtain the detection results of the temperature difference of all solar cells. It should be understood that, after each detection of the temperature difference between 24 battery cells, the temperature difference can be directly compared with a preset threshold to determine whether any two battery cells corresponding to the temperature difference have leakage abnormalities. If the temperature difference between two battery cells is greater than the preset threshold, the battery cell with the higher temperature is identified as the battery cell with leakage abnormalities. Alternatively, step S3 can be executed to determine the abnormality after the temperature difference between all battery cells has been detected.

[0042] Step S3: Compare the temperature difference with a preset threshold to determine whether a cell leakage abnormality has occurred.

[0043] In this embodiment, when the temperature difference is greater than the preset threshold, it is determined that a battery cell leakage abnormality has occurred, and the battery cell with the higher temperature among the two battery cells with temperature differences is determined to be the battery cell with leakage abnormality.

[0044] Based on the photovoltaic module cell anomaly detection method provided in steps S1 to S3 above, when applied to outdoor photovoltaic module testing, when the photovoltaic module under test is not connected to the grid, the positive and negative terminals of the module can be directly short-circuited via an extension cable. When the outdoor solar light source is relatively stable, this is equivalent to meeting the preset test conditions. Then, using the aforementioned light shading method, the cell temperature is monitored using equipment such as an infrared temperature measuring camera to determine cell anomalies. When the photovoltaic module under test is connected to the grid, when the outdoor solar light source is relatively stable, this is equivalent to meeting the preset test conditions. The aforementioned light shading method can be directly used, and the cell temperature is monitored using equipment such as an infrared temperature measuring camera to determine cell anomalies.

[0045] Based on the photovoltaic module cell anomaly detection method provided in steps S1 to S3 above, when applied to laboratory testing, anomaly detection of photovoltaic module cells can be achieved using a single testing device. (See Appendix) Figure 2 , Figure 2 This is a schematic flowchart illustrating the main steps of an anomaly detection method for photovoltaic module cells based on a testing device, as provided in an embodiment of this application. Figure 2 As shown, the photovoltaic module cell anomaly detection method of this application embodiment mainly includes the following steps S101 to S104.

[0046] Step S101: Connect the photovoltaic module under test to the testing device;

[0047] The photovoltaic module under test includes at least one battery cell, and the battery cell includes at least one set of battery cells connected in series to form a battery string.

[0048] In one embodiment, the structure and composition of the testing device can be as follows: the testing device can be a box structure, and its components are arranged inside the box structure. Specifically, a light source, a temperature monitoring device, a current monitoring device, and a connection device can be arranged inside the box structure. In practical applications, the light source, the temperature monitoring device, the current monitoring device, and the connection device are all readily available in the prior art. For example, the light source is usually a simulated steady-state light source, the temperature monitoring device and the current monitoring device are usually implemented using sensors, and the connection device usually includes a photovoltaic connector and a junction box. Specifically, in this step, the testing device connects to the positive and negative terminals of the photovoltaic module under test through the photovoltaic connector. It should be understood that the junction box usually includes a positive junction box connected to the positive output terminal of the photovoltaic module, a negative junction box connected to the negative output terminal of the photovoltaic module, and an intermediate junction box connected between the positive and negative junction boxes. Each junction box contains a bypass diode connected in parallel across the two ends of the battery cell to protect the battery cell from damage caused by hot spot effects due to excessive leakage current.

[0049] For example, such as Figure 3 The diagram shown is a schematic representation of the structural composition of a testing device provided in this embodiment. Figure 3As shown, the testing device is a box structure used to provide a sealed testing space, namely the test box shown in the figure. The test box contains a simulated steady-state light source, a temperature monitoring device, a current monitoring device, and a connection device. The testing device connects to the positive and negative terminals of the photovoltaic module under test via the connection device. It should be understood that the figure only exemplarily shows that the connection device contains a bypass diode and a photovoltaic connector (i.e., the circles shown in the figure that connect to the positive output terminal "+" and the negative output terminal "-" of the photovoltaic module under test, respectively). The photovoltaic module under test shown in the figure includes cell unit 1, cell unit 2, and cell unit 3. Each cell unit contains two cell strings, where each cell string consists of eight cells connected in series. That is, cell unit 1 contains cell string 1 and cell string 2, cell unit 2 contains cell string 3 and cell string 4, and cell unit 3 contains cell string 5 and cell string 6.

[0050] Step S102: Based on the testing device, control the light source irradiance, ambient temperature and loop current between the positive and negative electrodes of the photovoltaic module under test so that the test conditions meet the preset test conditions.

[0051] The preset test conditions described in this embodiment may specifically include: the test conditions meet the STC test conditions and the loop current between the positive and negative terminals reaches its maximum.

[0052] In one implementation, based on Figure 3 The testing apparatus shown, in this step S102, can specifically include: under the action of the light source, based on the temperature monitoring device detecting that the light source irradiance and ambient temperature of the battery string of the photovoltaic module under test reach the STC test conditions, and based on the current monitoring device detecting that the loop current between the positive and negative electrodes of the photovoltaic module under test reaches its maximum, indicating that the test conditions have met the preset test conditions; specifically in this embodiment, the positive and negative electrodes of the photovoltaic module under test can be short-circuited to maximize the loop current between the positive and negative electrodes of the photovoltaic module under test. It should be understood that the STC test conditions are specifically an ambient temperature of 25°C and a light source irradiance of 1000W / ㎡.

[0053] For example, such as Figure 4 The diagram shown is a schematic representation of the composition of another testing device provided in this embodiment. Figure 4 Is Figure 3 The test device shown has an added variable resistor in its structure, specifically as follows: Figure 4 As shown, the added variable resistor is connected between the positive and negative terminals of the photovoltaic module under test.

[0054] In one implementation, based on Figure 4The test apparatus shown, in this step S102, may specifically include: under the action of the light source, based on the temperature monitoring device detecting that the light source irradiance and ambient temperature of the battery string of the photovoltaic module under test reach the STC test conditions, and based on the current monitoring device detecting that the loop current between the positive and negative electrodes of the photovoltaic module under test reaches the maximum, indicating that the test conditions have reached the preset test conditions; specifically in this embodiment, the variable resistor can be adjusted to make the loop current between the positive and negative electrodes of the photovoltaic module under test reach the maximum. It should be understood that the resistance value of the variable resistor can be adjusted from 0 to ∞.

[0055] Step S103: The solar cells forming a battery string in the photovoltaic module under test are shaded according to a preset shading ratio, and the temperature of the unshaded solar cells in the battery string is detected to obtain the temperature difference between the unshaded solar cells.

[0056] In one embodiment, the photovoltaic module includes n sets of battery strings, where n ≥ 1. Step S103 may specifically include:

[0057] The area occupied by at least half of the battery cells in each of the n battery strings is defined as the light-shielding area, and the area occupied by the remaining battery cells is defined as the non-light-shielding area. After the light-shielding area is blocked from light for a preset time, the temperature of at least half of the battery cells in the n battery strings is detected, and the temperature difference between the individual battery cells is obtained based on the detected temperature of each battery cell.

[0058] The shaded area and the non-shaded area are interchanged to detect the temperature of the remaining number of battery cells in the n sets of battery strings, and the temperature difference between the individual battery cells is obtained based on the detected temperature of each battery cell.

[0059] In one embodiment, the photovoltaic module includes 2n sets of cell strings, where n ≥ 1, and step S103 specifically includes:

[0060] Two battery strings are selected from the 2n battery strings each time to perform the following steps 1031 and 1032 until the detection of all battery strings is completed.

[0061] Step 1031: Determine the area occupied by at least half of the battery cells in the two sets of battery strings as the light-shielding area, and the area occupied by the remaining battery cells as the non-light-shielding area. After the light-shielding area is blocked for a preset time, the temperature of at least half of the battery cells in the two sets of battery strings is detected, and the temperature difference between the individual battery cells is obtained based on the detected temperature of each battery cell.

[0062] Step 1032: For each of the two sets of battery strings selected, the shaded area and the non-shaded area are interchanged to detect the temperature of the remaining number of battery cells in the two sets of battery strings, and the temperature difference between the individual battery cells is obtained based on the detected temperature of each battery cell.

[0063] In this embodiment, a shading device can be used to block light in the shading area. For example, the shading device can be a zero-transmittance component. Alternatively, the zero-transmittance component can be fixed in the test box in a slidable manner through structural design, so as to achieve the purpose of blocking light in the cell string of the photovoltaic module according to a preset shading ratio.

[0064] Step S104: Compare the temperature difference with a preset threshold to determine whether a cell leakage abnormality has occurred.

[0065] For example, the preset threshold can be set to 1.

[0066] This step may specifically include: when the temperature difference between any two battery cells is detected to be greater than 1°C, it is determined that a battery cell leakage abnormality has occurred, and it can be determined that the battery cell with the higher temperature among the two battery cells with a temperature difference greater than 1°C has a leakage abnormality.

[0067] To better understand the implementation of the photovoltaic module cell anomaly detection method proposed in steps S101 to S104 above, the following is in conjunction with the appendix. Figure 5 and 6 The actual application scenarios shown are explained in detail.

[0068] like Figure 5 The figure shows an application scenario of the photovoltaic module cell anomaly detection method according to an embodiment of this application. In the application scenario shown, the photovoltaic module under test includes 6 sets of cell strings, totaling 48 cells. The testing device shown in this application scenario is the test box and the various components arranged inside the test box. When using this testing device to perform cell anomaly detection on the photovoltaic module under test, the light shading, temperature detection, and anomaly judgment according to a preset shading ratio can specifically be as follows: shading, temperature detection, and anomaly judgment are performed on 8 cells out of the 48 cells each time. For example, as shown... Figure 5As shown, using the location of the bypass diode in the connection device as the dividing line, each cell string in the photovoltaic module can be divided into an upper half and a lower half. When determining the shading area, the eight cells to be shaded each time can be selected as the upper or lower half of two sets of cells connected in series. The corresponding upper or lower half of each pair of sets of cells then constitutes the shading area determined each time. For example, if the upper half of cells 1 and 2 (a total of eight cells) is shaded, the shading area is shown as the black area in the figure. The specific implementation method for shading, temperature detection, and anomaly judgment of eight out of 48 cells each time is as follows:

[0069] a1. Connect the testing device to the photovoltaic module under test, where “+” and “-” in the figure refer to the positive and negative output terminals of the photovoltaic module, respectively;

[0070] a2. Control the light source irradiance to 1000W / ㎡ and the ambient temperature to 25℃ according to requirements;

[0071] a3. After turning on the light source and providing stable irradiation, adjust the variable resistor and observe the current with a current monitoring device. When the current loop is at its maximum, stabilize the resistance value of the variable resistor.

[0072] a4. Using a 0 transmittance device, cover the upper half of "battery string 1" and the upper half of "battery string 2". After stabilizing for 5-10 minutes, monitor the temperature of each cell in the lower half of "battery string 1" and the lower half of "battery string 2". If there is no significant temperature difference between the cells (less than 1°C), the cells in the lower half of "battery string 1" and the lower half of "battery string 2" are considered to have no leakage abnormality. If there is a significant temperature difference between the cells (greater than 1°C), the cell with the higher temperature in the lower half of "battery string 1" and the lower half of "battery string 2" is considered to have leakage abnormality.

[0073] After the assessment is completed, remove the obstructions and allow the area to stabilize for 10 minutes before proceeding to the next step.

[0074] a5. Following the testing method in step a4 above, perform the following tests in sequence:

[0075] By blocking the lower half of "battery string 1" and the lower half of "battery string 2", determine whether there are any abnormalities in the battery cells in the upper half of "battery string 1" and the upper half of "battery string 2".

[0076] By blocking the upper half of battery string 3 and the upper half of battery string 4, determine whether there are any abnormalities in the battery cells in the lower half of battery string 3 and the lower half of battery string 4.

[0077] By obscuring the lower half of battery string 3 and the lower half of battery string 4, determine whether there are any abnormalities in the battery cells of the upper half of battery string 3 and the upper half of battery string 4.

[0078] By blocking the upper half of battery string 5 and the upper half of battery string 6, determine whether there are any abnormalities in the battery cells in the lower half of battery string 5 and the lower half of battery string 6.

[0079] By blocking the lower half of battery string 5 and the lower half of battery string 6, determine whether there are any abnormalities in the battery cells in the upper half of battery string 5 and the upper half of battery string 6.

[0080] like Figure 6 The figure shows an application scenario of the photovoltaic module cell anomaly detection method according to an embodiment of this application. In the application scenario shown, the photovoltaic module under test includes 6 sets of cell strings, totaling 48 cells. The testing device shown in this application scenario is the test box and the various components arranged inside the test box. When using this testing device to perform cell anomaly detection on the photovoltaic module under test, the light shading according to a preset shading ratio specifically involves shading, temperature detection, and anomaly judgment on 24 of the 48 cells. For example, as shown... Figure 6 As shown, using the location of the bypass diode in the connection device as the dividing line, each cell string in the photovoltaic module can be divided into an upper half and a lower half. When determining the shading area, the 24 cells to be shaded each time can be selected as either the upper half or the lower half of all cell strings. The corresponding upper or lower half of all cell strings then becomes the shading area determined each time. For example, if the upper half of cell strings 1-6 (a total of 24 cells) is shaded, the shading area is shown as the black area in the figure. The specific implementation method for shading, temperature detection, and anomaly judgment of 24 cells out of 48 cells each time is as follows:

[0081] b1. Connect the test device to the photovoltaic module under test, where “+” and “-” in the figure refer to the positive and negative output terminals of the photovoltaic module, respectively;

[0082] b2. Control the light source irradiance to 1000W / ㎡ and the ambient temperature to 25℃ according to requirements;

[0083] b3. After turning on the light source and providing stable irradiation, adjust the variable resistor and observe the current with a current monitoring device. When the current loop is at its maximum, stabilize the resistance value of the variable resistor.

[0084] b4. Using a zero-transmittance device, cover the upper half of "battery string 1", "battery string 2", "battery string 3", "battery string 4", "battery string 5", and "battery string 6". After stabilizing for 5-10 minutes, monitor the temperature of each cell in "battery string 1", "battery string 2", "battery string 3", "battery string 4", "battery string 5", and "battery string 6".

[0085] If there is no significant temperature difference between the cells (the difference is less than 1℃), then the cells in the lower half of battery string 1, the lower half of battery string 2, the lower half of battery string 3, the lower half of battery string 4, the lower half of battery string 5, and the lower half of battery string 6 are determined to have no leakage abnormalities.

[0086] If there is a significant temperature difference between the cells (greater than 1°C), the cell with the highest temperature in the "lower half of battery string 1", "lower half of battery string 2", "lower half of battery string 3", "lower half of battery string 4", "lower half of battery string 5", and "lower half of battery string 6" is found to have a leakage abnormality.

[0087] After the assessment is completed, remove the obstructions and allow the area to stabilize for 10 minutes before proceeding to the next step.

[0088] b5. Refer to the testing method in step b4 above;

[0089] Similarly, by blocking the lower half of "battery string 1", "battery string 2", "battery string 3", "battery string 4", "battery string 5", and "battery string 6", we can determine whether there are any abnormalities in the battery cells of "battery string 1", "battery string 2", "battery string 3", "battery string 4", "battery string 5", and "battery string 6".

[0090] It should be noted that although the steps in the above embodiments are described in a specific order, those skilled in the art will understand that in order to achieve the effect of this application, different steps do not necessarily have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders. These adjusted solutions are equivalent to the technical solutions described in this application and therefore will also fall within the protection scope of this application.

[0091] The technical solution of this application has been described above with reference to one embodiment shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of this application.

Claims

1. A method for detecting abnormalities in photovoltaic module cells, characterized in that, The method includes: Step S1: Control the light source irradiance, ambient temperature and loop current between the positive and negative electrodes of the photovoltaic module under test so that the test conditions reach the preset test conditions. The photovoltaic module under test includes at least one battery cell, and the battery cell includes at least one set of battery cells connected in series to form a battery string. Step S2: The solar cells forming a battery string in the photovoltaic module under test are shaded according to a preset shading ratio, and the temperature of the unshaded solar cells in the battery string is detected to obtain the temperature difference between the unshaded solar cells. Step S3: Compare the temperature difference with a preset threshold to determine whether a cell leakage abnormality has occurred.

2. The photovoltaic module cell anomaly detection method according to claim 1, characterized in that, Step S1 includes: The photovoltaic module under test is connected to the testing device, and the light source irradiance, ambient temperature and loop current between the positive and negative electrodes of the photovoltaic module under test are controlled by the testing device so that the test conditions reach the preset test conditions. The testing device is a box structure, and a light source, a temperature monitoring device, a current monitoring device, and a connection device are installed inside the box structure.

3. The photovoltaic module cell anomaly detection method according to claim 2, characterized in that, The process of connecting the photovoltaic module under test to the testing device includes: The testing device is connected to the positive and negative terminals of the photovoltaic module under test via the connecting device.

4. The photovoltaic module cell anomaly detection method according to claim 2, characterized in that, The step of controlling the light source irradiance, ambient temperature, and loop current between the positive and negative electrodes of the photovoltaic module under test based on the testing device to ensure that the testing conditions meet the preset testing conditions includes: Under the influence of the light source, the light source irradiance and ambient temperature of the battery string of the photovoltaic module under test are detected by the temperature monitoring device to meet the standard test conditions. When the loop current between the positive and negative electrodes of the photovoltaic module under test is detected by the current monitoring device to reach its maximum, it indicates that the test conditions have met the preset test conditions.

5. The photovoltaic module cell anomaly detection method according to claim 2, characterized in that, The housing structure is also equipped with a variable resistor, which is connected between the positive and negative terminals of the photovoltaic module under test. Step S1 further includes: maximizing the loop current between the positive and negative terminals of the photovoltaic module under test by short-circuiting the positive and negative terminals, or maximizing the loop current between the positive and negative terminals of the photovoltaic module under test by adjusting the variable resistor.

6. The photovoltaic module cell anomaly detection method according to claim 1, characterized in that: The photovoltaic module comprises n sets of battery strings, where n ≥ 1, and step S2 specifically includes: The area occupied by at least half of the battery cells in each of the n battery strings is defined as the light-shielding area, and the area occupied by the remaining battery cells is defined as the non-light-shielding area. After the light-shielding area is blocked from light for a preset time, the temperature of at least half of the battery cells in the n battery strings is detected, and the temperature difference between the individual battery cells is obtained based on the detected temperature of each battery cell. The shaded area and the non-shaded area are interchanged to detect the temperature of the remaining number of battery cells in the n sets of battery strings, and the temperature difference between the individual battery cells is obtained based on the detected temperature of each battery cell.

7. The photovoltaic module cell anomaly detection method according to claim 1, characterized in that: The photovoltaic module comprises 2n sets of cell strings, where n ≥ 1. Step S2 specifically includes: Two battery strings are selected from the 2n battery strings each time to perform the following steps S21 and S22 until all battery strings have been detected. Step S21: The area occupied by at least half of the battery cells in the two sets of battery strings is determined as the light-shielding area, and the area occupied by the remaining battery cells is determined as the non-light-shielding area. After the light-shielding area is blocked for a preset time, the temperature of at least half of the battery cells in the two sets of battery strings is detected, and the temperature difference between the individual battery cells is obtained based on the detected temperature of each battery cell. Step S22: For each of the two sets of battery strings selected, the shaded area and the non-shaded area are interchanged to detect the temperature of the remaining number of battery cells in the two sets of battery strings, and the temperature difference between the individual battery cells is obtained based on the detected temperature of each battery cell.

8. The photovoltaic module cell anomaly detection method according to claim 6 or 7, characterized in that: The preset duration ranges from 5 to 10 minutes.

9. The photovoltaic module cell anomaly detection method according to claim 6 or 7, characterized in that: Specifically, the process of blocking light in the shaded area includes using a light-blocking device to block light in the shaded area.

10. The photovoltaic module cell anomaly detection method according to claim 9, characterized in that: Before exchanging the shaded area and the non-shaded area, the method further includes: removing the shaded device from the shaded area and waiting for 10 minutes before using the shaded device to block light from the newly determined shaded area.

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