Method and device for evaluating composite defects of photovoltaic modules under outdoor long-term working conditions

Abstract

This application provides a method and apparatus for evaluating composite defects in photovoltaic modules under long-term outdoor operating conditions, relating to the field of photovoltaic module testing technology. The method includes: performing imaging inspection on photovoltaic modules after outdoor aging to identify the defect types and severity levels of defective cells; classifying the cells into single-defect cells and composite-defect cells, and further grouping them according to defect type and severity level; calculating the single-defect power loss of each single-defect cell subgroup and the composite-defect power loss of each composite-defect cell subgroup; calculating the standard coupling coefficient for each defect combination; calculating the actual coupling coefficient based on the standard coupling coefficient and environmental parameters under actual outdoor operating conditions; and determining the corresponding cell processing strategy based on the actual coupling coefficient. This application can quantitatively assess the coupling amplification effect between composite defects and accurately reflect the performance degradation of the module under real operating conditions.

Description

Technical Field

[0001] This application relates to the field of photovoltaic module testing technology, and in particular to a method and apparatus for evaluating composite defects in photovoltaic modules under long-term outdoor operating conditions. Background Technology

[0002] During long-term outdoor operation, photovoltaic modules are subjected to a combination of environmental factors, including temperature cycling, ultraviolet radiation, mechanical stress, and humidity corrosion, inevitably leading to various types of defects such as microcracks, hot spots, grid breaks, and potential-induced degradation. These defects cause photovoltaic modules to experience power degradation, affecting power generation efficiency and lifespan.

[0003] Currently, imaging inspection technology has been widely used in the defect identification and evaluation of photovoltaic modules. For example, electroluminescence (EL) imaging technology can be used to detect defects such as microcracks, broken grids, and potential-induced decay, while infrared thermal imaging technology can be used to detect hot spot defects.

[0004] However, most existing defect assessment methods analyze single types of defects independently under standard test conditions. In actual outdoor aging processes, photovoltaic modules often exhibit multiple defects simultaneously, forming composite defects. These defects may interact, leading to a coupling amplification effect, resulting in power loss far exceeding the sum of the losses from individual defects. Furthermore, the degree of coupling is significantly affected by actual operating conditions such as ambient temperature, irradiance, humidity, and wind speed. Therefore, existing methods cannot quantify the coupling effect between composite defects, nor can they accurately reflect the performance degradation of modules under real-world conditions. Summary of the Invention

[0005] This application aims to address the technical problem that existing defect assessment methods cannot quantify the coupling effect between complex defects, nor can they accurately reflect the performance degradation of components under real-world operating conditions.

[0006] To solve the above-mentioned technical problems, the embodiments of this application are implemented through the following aspects.

[0007] In a first aspect, this application provides a method for evaluating composite defects in photovoltaic modules under long-term outdoor operating conditions, comprising: performing imaging detection on photovoltaic modules after outdoor aging to identify the defect type and severity level of defective cells; dividing the cells into single-defect cells and composite-defect cells, and further grouping them according to the defect type and severity level to obtain multiple single-defect cell subgroups and multiple composite-defect cell subgroups; calculating the single-defect power loss of each single-defect cell subgroup and the composite-defect power loss of each composite-defect cell subgroup; calculating the standard coupling coefficient for each defect combination based on the single-defect power loss and the composite-defect power loss; calculating the actual coupling coefficient based on the standard coupling coefficient and environmental parameters of the actual outdoor operating conditions; and determining the processing strategy for the corresponding cells based on the actual coupling coefficient.

[0008] Furthermore, the defect types include at least two of the following: microcracks, hot spots, broken grids, and potential-induced decay; the severity levels include three levels: slight, moderate, and severe.

[0009] Furthermore, each single-defect battery cell group corresponds to a defect type and a severity level, and each single-defect battery cell group includes multiple battery cells; each composite-defect battery cell group corresponds to two defect types and the severity levels corresponding to the two defect types, and each composite-defect battery cell group includes multiple battery cells.

[0010] Furthermore, the formula for calculating the standard coupling coefficient is as follows: ,in, The standard coupling coefficient is... The power loss is defined as the power loss due to the composite defect, and k is the defect type number in the composite defect cell. is the sum of the power losses of each defect type in the composite defect cell, and j is the defect type number in the single defect cell.

[0011] Further, the step of calculating the single-defect power loss of each of the single-defect cell groups and the composite-defect power loss of each of the composite-defect cell groups includes: measuring the IV curves of the cells in each of the single-defect cell groups and each of the composite-defect cell groups under standard test conditions, and calculating the single-defect power loss and the composite-defect power loss based on the IV curves.

[0012] Further, the step of calculating the single-defect power loss of each of the single-defect battery cell groups and the composite-defect power loss of each of the composite-defect battery cell groups includes: estimating the single-defect power loss and the composite-defect power loss based on the imaging detection image feature parameters of the battery cells in each of the single-defect battery cell groups and each of the composite-defect battery cell groups.

[0013] Further, the step of calculating the actual coupling coefficient based on the standard coupling coefficient and environmental parameters under actual outdoor conditions includes: obtaining environmental parameters under actual outdoor conditions, wherein the environmental parameters include the average ambient temperature, average irradiance, average humidity, and average wind speed within a preset statistical period in the region where the photovoltaic module is located; and calculating a temperature correction factor based on the average ambient temperature. The irradiance correction factor is calculated based on the average irradiance. Calculate the humidity correction factor based on the average humidity. Calculate the wind speed correction factor based on the average wind speed. ; Calculate environmental correction factors .

[0014] According to the formula Calculate the actual coupling coefficient, where The actual coupling coefficient The standard coupling coefficient is denoted as .

[0015] Furthermore, the step of determining the processing strategy for the corresponding solar cell based on the actual coupling coefficient includes: When the actual coupling coefficient is greater than the first preset threshold, it is determined to be strong coupling amplification, and an immediate replacement processing strategy is determined; when the actual coupling coefficient is greater than the upper limit of the preset tolerance range of the second preset threshold and less than or equal to the first preset threshold, it is determined to be weak coupling amplification, and a planned replacement or enhanced monitoring processing strategy is determined; when the actual coupling coefficient is within the preset tolerance range of the second preset threshold, it is determined to be no coupling, and a periodic inspection processing strategy is determined; when the actual coupling coefficient is less than the lower limit of the preset tolerance range of the second preset threshold, it is determined to be a suppression effect, and a routine monitoring processing strategy is determined; wherein, the first preset threshold is greater than the second preset threshold, and the second preset threshold is set to 1.0.

[0016] Furthermore, after determining the processing strategy for the corresponding battery cell based on the actual coupling coefficient, the method further includes: constructing a coupling coefficient lookup table, which records the actual coupling coefficient of each defect combination under each severity level combination; and sorting the actual coupling coefficients in the coupling coefficient lookup table from high to low to select the most dangerous defect combination.

[0017] Secondly, this application provides a photovoltaic module composite defect evaluation device under long-term outdoor operating conditions, comprising: an imaging detection module for imaging detection of photovoltaic modules after outdoor aging, identifying the defect type and severity level of defective cells; a grouping module for dividing the cells into single-defect cells and composite-defect cells, and further grouping them according to the defect type and severity level to obtain multiple single-defect cell subgroups and multiple composite-defect cell subgroups; a power loss calculation module for calculating the single-defect power loss of each single-defect cell subgroup and the composite-defect power loss of each composite-defect cell subgroup; a standard coupling coefficient calculation module for calculating the standard coupling coefficient for each defect combination based on the single-defect power loss and the composite-defect power loss; an actual coupling coefficient calculation module for calculating the actual coupling coefficient based on the standard coupling coefficient and environmental parameters of the actual outdoor operating conditions; and a processing strategy determination module for determining the processing strategy for the corresponding cells based on the actual coupling coefficient.

[0018] The technical advantages of this application are as follows: This application classifies defective solar cells into single-defect solar cells and compound-defect solar cells according to the number of defects, and further groups them according to defect type and severity level. It calculates the power loss of single defects and the power loss of compound defects separately, thereby constructing a standard coupling coefficient, which can quantitatively assess the coupling amplification effect between compound defects. Simultaneously, by obtaining environmental parameters from actual outdoor operating conditions, the actual coupling coefficient is calculated, correcting the coupling coefficient under standard test conditions to the coupling coefficient under real operating conditions. This fully considers the influence of factors such as ambient temperature, irradiance, humidity, and wind speed on the defect coupling effect, enabling the evaluation results to accurately reflect the performance degradation of photovoltaic modules under actual operating conditions. Furthermore, by determining the processing strategy for solar cells based on the actual coupling coefficient, it can provide a decision-making basis for differentiated operation and maintenance of photovoltaic modules, achieving reasonable allocation of operation and maintenance resources. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the method for evaluating composite defects of photovoltaic modules under long-term outdoor operating conditions, as provided in an embodiment of this application.

[0020] Figure 2 This is a schematic diagram of the structure of the outdoor long-term working condition photovoltaic module composite defect evaluation device provided in the embodiments of this application. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0023] The following description, in conjunction with the accompanying drawings, details the method and apparatus for evaluating composite defects of photovoltaic modules under long-term outdoor operating conditions provided in this application through specific embodiments and application scenarios.

[0024] Example 1 like Figure 1 As shown in Example 1, the method for evaluating composite defects of photovoltaic modules under long-term outdoor operating conditions specifically includes the following steps.

[0025] S1: Perform imaging inspection on outdoor aged photovoltaic modules to identify the defect types and severity levels of defective cells.

[0026] In this embodiment, imaging detection technology can be used to inspect photovoltaic modules and identify the types of defects in the solar cells. Electroluminescence (EL) imaging technology can be used to detect defects such as microcracks, broken grids, and potential-induced degradation (PID), while infrared thermal imaging technology can be used to detect hot spot defects. In this embodiment, the defect types include four types: microcracks, hot spots, broken grids, and PID.

[0027] For each defect type, it is classified into three levels according to its severity: minor, moderate, and severe. Specifically, microcracks can be classified based on crack length, width, and number, or based on the proportion of the area of ​​the crack's dark line region to the total area of ​​the single cell in the EL image; hot spots can be classified based on the temperature difference between the hot spot area and the normal area and the area of ​​the hot spot, or based on the proportion of the hot spot area to the total area of ​​the single cell; broken grids can be classified based on the number of broken grids and the proportion of the broken grid area to the total area of ​​the grid lines; and PID (Potential Injury Point) can be classified based on the attenuation rate of grayscale values ​​relative to normal cells in the EL image and the affected area.

[0028] Specifically, in this embodiment, microcracks are classified according to the proportion of the area of ​​the dark crack line region in the EL image to the total area of ​​a single solar cell. A proportion less than 5% is considered minor, 5%-15% is moderate, and greater than 15% is severe. Hot spots are classified based on the temperature difference between the hot spot area and the normal area, as well as the hot spot area. A temperature difference less than 10℃ and a hot spot area less than 10% of the solar cell area is considered minor; a temperature difference of 10℃-25℃ or a hot spot area of ​​10%-30% of the solar cell area is considered moderate; and a temperature difference greater than 25℃ or a hot spot area greater than 30% of the solar cell area is considered severe. Gate breaks are classified according to the proportion of the dark area of ​​the gate line in the EL image to the total area of ​​the gate line. A proportion less than 10% is considered minor, 10%-25% is moderate, and greater than 25% is severe. PID (Potential Ingress / Degradation) is classified based on the attenuation rate of the grayscale value relative to a normal solar cell in the EL image. An attenuation rate less than 15% is considered minor, 15%-30% is moderate, and greater than 30% is severe.

[0029] The above threshold values ​​are all exemplary values, and can be adjusted according to testing standards and engineering experience in actual applications.

[0030] Through the above steps, accurate identification and classification of photovoltaic module defect types and severity were achieved, providing reliable basic data for subsequent defect grouping and power loss calculation.

[0031] S2: Divide the solar cells into single-defect solar cells and compound-defect solar cells, and further group them according to the defect type and severity level to obtain multiple single-defect solar cell subgroups and multiple compound-defect solar cell subgroups.

[0032] Based on the cell defect information recorded in step S1, the number of defect types present in each defective cell is counted. If a cell has only one defect type, it is classified as a single-defect cell; if a cell has two or more defect types, it is classified as a composite-defect cell. Considering that in actual working conditions, it is relatively common for a cell to have two defect types simultaneously, while it is rare for it to have three or more defect types simultaneously, in this embodiment, a composite-defect cell is defined as a cell that contains two defect types simultaneously.

[0033] For a single defective solar cell, it is further grouped according to its defect type and severity level to obtain multiple single defective solar cell subgroups. Each single defective solar cell subgroup corresponds to a combination of a defect type and a severity level, and each subgroup includes multiple solar cells. For example, when the defect types include four types—microcracks, hot spots, broken grids, and potential-induced degradation—and the severity levels include three levels—slight, moderate, and severe—a maximum of 12 single defective solar cell subgroups can be formed, as shown in Table 1.

[0034] Table 1 List of Cell Groups with Single Defects

[0035] For composite defect solar cells, they are further grouped according to the two defect types they contain and the severity levels corresponding to each defect type, resulting in multiple composite defect cell subgroups. Each composite defect cell subgroup corresponds to a combination of two defect types and the severity levels corresponding to each defect type, and each subgroup includes multiple solar cells. For example, when there are four defect types and three severity levels, there are a total of [number missing] ways to combine the two types of defects. There are 54 composite defect cell groups, with each combination corresponding to 3×3=9 severity level combinations, as shown in Table 2.

[0036] Table 2 List of Cell Groups with Composite Defects

[0037] In Table 2, "Defect 1" and "Defect 2" correspond to the first and second defects in the defect combination, respectively. For example, in the "microcrack + hot spot" combination, defect 1 is a microcrack and defect 2 is a hot spot.

[0038] Through the above steps, a refined classification of defective solar cells is achieved. Defective solar cells are systematically grouped according to the number, type, and severity of defects, so that the subsequent calculation of coupling coefficients can be performed separately for different defect combinations, thereby improving the pertinence and accuracy of the evaluation.

[0039] S3: Calculate the single-defect power loss of each single-defect cell group and the combined-defect power loss of each combined-defect cell group.

[0040] In this embodiment, the step involves measuring the current-voltage (IV) curves of the cells in each of the single-defect cell groups and each of the composite-defect cell groups under standard test conditions, and calculating the single-defect power loss and composite-defect power loss based on the IV curves.

[0041] Specifically, power loss is defined as the difference between the reference power of a defect-free solar cell and the maximum power point power of a defective solar cell. The reference power is obtained by acquiring the factory average power data of solar cells of the same model as the one under test, which is used as the reference power.

[0042] Under standard test conditions (STC: irradiance 1000 W / m²) 2 (Battery temperature 25℃, atmospheric quality AM1.5) The IV curve of each cell in each single defect cell group and each composite defect cell group was measured using an IV curve tester to obtain the maximum power point power of each cell.

[0043] For each subgroup of cells with a single defect, first calculate the power loss of the i-th cell in that subgroup:

[0044] in, Let i be the power loss of the i-th cell in a single defective cell group. For reference power, This is the maximum power point power of the solar cell.

[0045] Then, the average power loss of each cell in the subgroup is calculated as the single-defect power loss of the subgroup:

[0046] in, For the single-defect power loss of the j-th group of single-defect solar cells, The number of solar cells in this subgroup is j, which is taken from the group number in Table 1, i.e., S1-1 to S4-3.

[0047] For each subgroup of cells with composite defects, first calculate the power loss of the i-th cell in that subgroup:

[0048] in, The power loss of the i-th cell in the composite defect cell group is given by the following formula. For reference power, This is the maximum power point power of the solar cell.

[0049] Then, the average power loss of each cell in the subgroup is calculated as the composite defect power loss of the subgroup:

[0050] in, The power loss due to composite defects in the k-th group of solar cells is given by [the power loss due to composite defects]. The number of solar cells in this subgroup is k, which is the group number in Table 2, i.e., D1-1 to D6-9.

[0051] Through the above steps, the power loss of a single defect in each subgroup of individually defective solar cells and the power loss of a composite defect in each subgroup of composite defective solar cells were obtained, providing necessary data support for the subsequent calculation of the standard coupling coefficient. Using the average power loss of multiple solar cells within a subgroup effectively reduces the impact of individual cell measurement errors on the results and improves the reliability of the power loss data.

[0052] S4: Calculate the standard coupling coefficient for each defect combination based on the power loss of a single defect and the power loss of a composite defect.

[0053] Specifically, for each defect combination, the standard coupling coefficient is calculated based on its corresponding single defect power loss and composite defect power loss.

[0054] The formula for calculating the standard coupling coefficient is:

[0055] in, The standard coupling coefficient is... The power loss is defined as the power loss due to the composite defect, and k is the defect type group number in the composite defect cell. is the sum of the power losses of each defect type in the composite defect cell, and j is the defect type group number in the single defect cell.

[0056] When composite defect solar cells contain only two types of defects...

[0057] in, and These represent the power loss of a single defect for each of the two defect types in the composite defect.

[0058] For example, for the defect combination of microcrack-slight + hot spot-moderate, the standard coupling coefficient is:

[0059] in, Composite defect power loss in battery cell arrays. For single-defect power loss in a (microcrack-minor) single-defect solar cell array, Single-defect power loss in a single-defect cell array.

[0060] Standard Coupling Coefficient The physical meaning is as follows: when When the value is greater than 1, it indicates that there is a coupling amplification effect between the two defects, and the power loss caused by the composite defect is greater than the sum of the power losses of the two single defects. when When =1, it means that there is no coupling effect between the two defects, and the power loss caused by the composite defect is equal to the sum of the power losses of the two single defects; when When <1, it indicates that there is a suppressive effect between the two defects, and the power loss caused by the composite defect is less than the sum of the power losses of the two single defects.

[0061] Through the above steps, a standard coupling coefficient was constructed, enabling a quantitative assessment of the coupling effect between composite defects. The standard coupling coefficient intuitively reflects the degree to which the interaction between the two defects amplifies or suppresses power loss, thus overcoming the technical limitation of existing methods that cannot quantitatively characterize the coupling effect of composite defects.

[0062] S5: Calculate the actual coupling coefficient based on the standard coupling coefficient and the environmental parameters of the actual outdoor working conditions.

[0063] This step specifically includes the following sub-steps: S5.1: Obtain environmental parameters under actual outdoor working conditions.

[0064] Environmental parameters include the average ambient temperature, average irradiance, average humidity, and average wind speed of the region where the photovoltaic modules are located within a preset statistical period. The preset statistical period can be set according to actual needs, ranging from 1 to 5 years; in this embodiment, it can be set to the past 3 years.

[0065] S5.2: Calculate the corresponding correction factor based on each environmental parameter.

[0066] Temperature correction factor:

[0067] in, This is a temperature correction factor. The average ambient temperature, For reference temperature, This is the temperature correction factor.

[0068] Irradiation correction factor:

[0069] in, For the irradiation correction factor, The average irradiance, For reference irradiance, This is the irradiation correction factor.

[0070] Humidity correction factor:

[0071] in, Humidity correction factor The average humidity. For reference humidity, This is the humidity correction factor.

[0072] Wind speed correction factor:

[0073] in, For wind speed correction factor, The average wind speed, For reference wind speed, This is the wind speed correction factor.

[0074] In this embodiment, the reference temperature The battery temperature can be set to 25°C under standard test conditions (STC), with reference irradiance. An irradiance of 1000 W / m² under STC can be taken. 2 Reference humidity 0% RH (based on dry conditions) can be used, with reference to wind speed. 0 m / s can be taken as the reference (based on windless conditions); temperature correction factor The exemplary value range is 0.003~0.005 / ℃ (based on the power temperature coefficient of crystalline silicon cells), and the irradiation correction coefficient is... The exemplary value range is 0.0001~0.001 / (W / m 2 Humidity correction factor The exemplary value range is 0.001 to 0.005 / %RH, wind speed correction factor. The exemplary value range is 0.005 to 0.02 / (m / s). The above reference values ​​and coefficient ranges are exemplary values, and can be adjusted according to the component type and local climate conditions in actual applications.

[0075] S5.3: Calculate the environmental correction factor :

[0076] S5.4: Calculate the actual coupling coefficient :

[0077] in, The actual coupling coefficient, The standard coupling coefficient.

[0078] Through the above steps, the standard coupling coefficient under standard test conditions is corrected to the actual coupling coefficient under actual outdoor conditions. This fully considers the influence of factors such as ambient temperature, irradiance, humidity, and wind speed on the defect coupling effect, so that the evaluation results can accurately reflect the performance degradation of photovoltaic modules under real operating conditions and improve the engineering practical value of the evaluation results.

[0079] S6: Determine the processing strategy for the corresponding solar cell based on the actual coupling coefficient.

[0080] Specifically, based on the comparison between the actual coupling coefficient and the first and second preset thresholds, a processing strategy for the corresponding defect combination is determined. The first preset threshold is greater than the second preset threshold. The second preset threshold is exemplarily set to 1.0, and the first preset threshold is exemplarily set to 1.5; the specific values ​​are set based on actual engineering experience and operational requirements.

[0081] When the actual coupling coefficient exceeds the first preset threshold of 1.5, it is determined to be a strong coupling amplification effect, indicating that the interaction between the two defects significantly exacerbates the power loss. The coupling effect causes the power loss of the composite defect to exceed 50% of the sum of the power losses of each individual defect, and an immediate replacement strategy is determined. The immediate replacement strategy includes adding the battery cell corresponding to the defect combination to the emergency replacement list and completing the replacement within the next maintenance cycle.

[0082] When the actual coupling coefficient is greater than the upper limit of the preset tolerance range of 1.05 but less than or equal to the first preset threshold of 1.5, it is determined to be a weak coupling amplification effect, indicating that the interaction between the two defects exacerbates the power loss to a certain extent, and a treatment strategy of planned replacement or enhanced monitoring is determined. The treatment strategy of planned replacement includes: adding the battery cell corresponding to the defect combination to the planned replacement list and arranging replacement in subsequent maintenance cycles; the treatment strategy of enhanced monitoring includes: shortening the detection cycle of the battery cell and increasing the detection frequency.

[0083] When the actual coupling coefficient is within the preset tolerance range of the second preset threshold of 1.0, it is determined that there is no coupling effect, indicating that the interaction between the two defects has no significant impact on power loss. The power loss of the composite defect is approximately equal to the sum of the power losses of each individual defect, thus determining the processing strategy for periodic inspection. The processing strategy for periodic inspection includes: performing periodic inspections on the solar cell according to the regular inspection cycle. The preset tolerance range can be set to ±0.01 to ±0.1, and in this embodiment, it can be set to ±0.05.

[0084] When the actual coupling coefficient is less than the lower limit of the preset tolerance range of 0.95, it is determined to be a suppression effect, indicating that the interaction between the two defects suppresses power loss to a certain extent. The power loss of the composite defect is less than the sum of the power losses of each individual defect, and the processing strategy for routine monitoring is determined. The processing strategy for routine monitoring includes: performing routine monitoring on the solar cell according to the standard monitoring procedure.

[0085] Through the above steps, defect combinations are classified and treated according to the actual coupling coefficient, providing a clear decision-making basis for differentiated operation and maintenance of photovoltaic modules. Defect combinations with significant coupling effects are given priority, while those with weak coupling effects or suppression effects are subject to routine monitoring. This achieves reasonable allocation of operation and maintenance resources and improves operation and maintenance efficiency.

[0086] The following numerical calculation example illustrates the implementation process of the above method. Assume that the reference power (Pref) of the crystalline silicon photovoltaic modules used in an outdoor photovoltaic power station is 5.0W. Through imaging detection and IV curve measurement, the following data were obtained: the average maximum power point power of the microcrack-slightly cracked subgroup (S1-1) is 4.8W, and the power loss per defect is... ΔP single，S1-1 =5.0-4.8=0.2W; The average maximum power point power of the hot spot-medium subgroup (S2-2) is 4.5W, and the power loss per defect is... ΔP single，S2-2 =5.0-4.5=0.5W; The average maximum power point power of the composite defect subgroup (D1-2) of microcrack-slight + hot spot-moderate composite defect is 4.0W, and the power loss of composite defects is 0.5W. ΔP single，D1-2 =5.0 - 4.0 = 1.0W. Standard coupling coefficient C STC =1.0 / (0.2+0.5)=1.43. Assume the average ambient temperature T in this region over the past 3 years is... avg =35℃, average irradiance G avg =800W / m 2 Average humidity H avg =60%RH, average wind speed W avg =3m / s. Take α T =0.004 / ℃, α G =0.0005 / (W / m 2 ), α H =0.003 / %RH α W =0.01 / (m / s), f T =1 + 0.004 × (35 - 25) = 1.04; fG =1 + 0.0005 × (800 - 1000) = 0.90; f H =1+0.003×(60-0)=1.18; f W =1 + 0.01 × (3 - 0) = 1.03. K env =1.04×0.90×1.18×1.03=1.138. C actual =1.43 × 1.138 = 1.628. Since C actual =1.628 > the first preset threshold of 1.5, which is determined to be a strong coupling amplification effect, and the processing strategy of immediate replacement is determined.

[0087] Example 2 This embodiment improves upon step S3 in embodiment 1. In this embodiment, step S3 uses an imaging extrapolation algorithm to calculate the power loss of a single defect and the power loss of a composite defect; the remaining steps are the same as in embodiment 1.

[0088] In this embodiment, step S3 includes: calculating the power loss of a single defect and the power loss of a composite defect based on the imaging detection image feature parameters of the cells in each single defect cell group and each composite defect cell group.

[0089] Specifically, the image feature parameters of the imaging detection are extracted according to different defect types: Hidden cracks: The proportion of the area of ​​the dark crack line region to the total area of ​​a single cell and the average crack width are extracted from the EL image. Fragmentation: Extract the proportion of dark area in the raster lines to the total area of ​​the raster lines from the EL image; Potential-induced decay: Extracting the decay rate of grayscale values ​​relative to normal cells based on EL images; Hot spot: The temperature difference between the hot spot area and the normal area, as well as the proportion of the hot spot area to the total area of ​​a single solar cell, are extracted based on infrared thermal imaging data.

[0090] Based on the preset feature parameter-power loss mapping relationship, the power loss of each battery cell is calculated according to the feature parameters of the imaging detection image. The feature parameter-power loss mapping relationship is pre-established in the following way: Standard sample solar cells with different defect types and severity levels were collected. The actual power loss of each standard sample solar cell was measured under standard test conditions, and imaging detection data was collected simultaneously to extract the defect feature parameters of each standard sample solar cell. The defect feature parameters of each standard sample solar cell were correlated with the corresponding actual power loss to establish a feature parameter-power loss mapping table.

[0091] During the estimation, based on the defect type of the solar cell under test, the corresponding defect feature parameters are extracted, and the standard sample that is closest to its feature parameters is found in the mapping table. The power loss of the standard sample is used as the estimated power loss of the solar cell.

[0092] For each subgroup of cells with a single defect, the corresponding power loss is found in the mapping table based on the defect characteristic parameters of each cell in the subgroup. The average value of the estimated power loss of all cells in the subgroup is then calculated as the single defect power loss of the subgroup.

[0093] For each subgroup of cells with two types of defects, the corresponding power loss is found in the mapping table based on the combination of the two defect characteristic parameters of each cell in the subgroup. The average value of the estimated power loss of all cells in the subgroup is then calculated as the power loss of the composite defects of the subgroup.

[0094] By following the steps above, power loss can be calculated directly from the imaging detection results without disassembling the battery cells for laboratory measurements, thus achieving non-destructive power loss assessment, improving detection efficiency, and reducing detection costs.

[0095] The remaining steps of Example 2 are the same as those of Example 1, and will not be repeated here.

[0096] Example 3 This embodiment is an improvement on embodiment 1. The difference is that after step S6, it also includes: constructing a coupling coefficient comparison table; sorting the actual coupling coefficients in the coupling coefficient comparison table from high to low, and screening the most dangerous defect combination.

[0097] The coupling coefficient comparison table records the actual coupling coefficients of each defect combination under each severity level combination.

[0098] Specifically, a defect combination comparison table is constructed by associating the defect type combination, severity level combination, actual coupling coefficient and corresponding treatment strategy of each composite defect cell group.

[0099] For example, the defect combination comparison table is shown in Table 3.

[0100] Table 3 Defect Combination Comparison Table

[0101] In Table 3, the actual coupling coefficient and processing strategy columns can be filled in according to the actual calculation results. For example, Table 3 gives several actual coupling coefficient values ​​and processing strategies.

[0102] Then, sort the defect combinations in Table 3 from high to low according to their actual coupling coefficients, and select the top N defect combinations with the largest actual coupling coefficients as the defect combinations that need to be prioritized for processing. N is set according to actual engineering experience.

[0103] This embodiment, through the above steps, enables an intuitive display and priority ranking of the coupling risks of various defect combinations, facilitating operations and maintenance personnel to quickly identify the most dangerous defect combinations, rationally allocate operations and maintenance resources, and provide a scientific basis for operations and maintenance decisions.

[0104] Based on the aforementioned method for evaluating composite defects in photovoltaic modules under long-term outdoor operating conditions, this application discloses a device for evaluating composite defects in photovoltaic modules under long-term outdoor operating conditions, such as... Figure 2 As shown, the device mainly includes: The imaging detection module 210 is used to perform imaging detection on outdoor aged photovoltaic modules to identify the defect type and severity level of defective cells. Grouping module 220 is used to divide the defective battery cells into single-defect battery cells and compound-defect battery cells according to the number of defects, and further group them according to the defect type and the severity level to obtain multiple single-defect battery cell subgroups and multiple compound-defect battery cell subgroups. The power loss calculation module 230 is used to calculate the single-defect power loss of each of the single-defect battery cell groups and the composite-defect power loss of each of the composite-defect battery cell groups, respectively. The standard coupling coefficient calculation module 240 is used to calculate the standard coupling coefficient of various defect combinations based on the power loss of the single defect and the power loss of the composite defect, respectively. The actual coupling coefficient calculation module 250 is used to calculate the actual coupling coefficient based on the standard coupling coefficient and the environmental parameters of the actual outdoor working conditions. The processing strategy determination module 260 is used to determine the processing strategy for the corresponding battery cell based on the actual coupling coefficient.

[0105] The above modules are used to implement each step of the above-described photovoltaic module composite defect evaluation method embodiment and can achieve the same technical effect. To avoid repetition, they will not be described again here.

[0106] Finally, it should be noted that: The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for evaluating composite defects in photovoltaic modules under long-term outdoor operating conditions, characterized in that, include: Imaging inspection is performed on outdoor aged photovoltaic modules to identify the defect types and severity levels of defective cells; The solar cells are divided into single-defect solar cells and compound-defect solar cells, and further grouped according to the defect type and the severity level to obtain multiple single-defect solar cell subgroups and multiple compound-defect solar cell subgroups. Calculate the single-defect power loss of each of the single-defect battery cell groups and the composite-defect power loss of each of the composite-defect battery cell groups respectively; Calculate the standard coupling coefficient for each defect combination based on the power loss of the single defect and the power loss of the composite defect; The actual coupling coefficient is calculated based on the standard coupling coefficient and the environmental parameters of the actual outdoor working conditions. The processing strategy for the corresponding battery cell is determined based on the actual coupling coefficient. The formula for calculating the standard coupling coefficient is as follows: in, The standard coupling coefficient is... The power loss is defined as the power loss due to the composite defect, and k is the defect type number in the composite defect cell. is the sum of the power losses of each defect type in the composite defect cell, and j is the defect type number in the single defect cell.

2. The method for evaluating composite defects in photovoltaic modules according to claim 1, characterized in that, The defect types include at least two of the following: microcracks, hot spots, broken grids, and potential-induced decay; the severity levels include three levels: slight, moderate, and severe.

3. The method for evaluating composite defects in photovoltaic modules according to claim 1, characterized in that, Each single-defect cell group corresponds to a defect type and a severity level, and each single-defect cell group includes multiple cells; each composite-defect cell group corresponds to two defect types and the severity levels corresponding to the two defect types, and each composite-defect cell group includes multiple cells.

4. The method for evaluating composite defects in photovoltaic modules according to claim 1, characterized in that, The calculation of the single-defect power loss of each of the single-defect cell groups and the combined-defect power loss of each of the combined-defect cell groups includes: Under standard test conditions, the IV curves of the cells in each of the single-defect cell groups and each of the composite-defect cell groups are measured, and the power loss of the single defect and the power loss of the composite defect are calculated based on the IV curves.

5. The method for evaluating composite defects in photovoltaic modules according to claim 1, characterized in that, The calculation of the single-defect power loss of each of the single-defect cell groups and the combined-defect power loss of each of the combined-defect cell groups includes: Based on the imaging detection image feature parameters of the cells in each of the single-defect battery cell groups and each of the composite-defect battery cell groups, the power loss of the single defect and the power loss of the composite defect are calculated.

6. The method for evaluating composite defects in photovoltaic modules according to claim 1, characterized in that, The calculation of the actual coupling coefficient based on the standard coupling coefficient and environmental parameters of the actual outdoor working conditions includes: Obtain environmental parameters under actual outdoor working conditions, including the average ambient temperature, average irradiance, average humidity, and average wind speed in the region where the photovoltaic module is located within a preset statistical period; Calculate the temperature correction factor based on the average ambient temperature. The irradiance correction factor is calculated based on the average irradiance. Calculate the humidity correction factor based on the average humidity. Calculate the wind speed correction factor based on the average wind speed. ; Calculate the environmental correction factor ; According to the formula Calculate the actual coupling coefficient, where The actual coupling coefficient is... The standard coupling coefficient is denoted as .

7. The method for evaluating composite defects in photovoltaic modules according to claim 1, characterized in that, The process of determining the corresponding solar cell based on the actual coupling coefficient includes: When the actual coupling coefficient is greater than the first preset threshold, it is determined to be a strong coupling amplification, and an immediate replacement processing strategy is determined. When the actual coupling coefficient is greater than the upper limit of the preset tolerance range of the second preset threshold and less than or equal to the first preset threshold, it is determined to be a weak coupling amplification, and a processing strategy of planning to replace or strengthen monitoring is determined. When the actual coupling coefficient is within the preset tolerance range of the second preset threshold, it is determined that there is no coupling, and a periodic inspection processing strategy is determined. When the actual coupling coefficient is less than the lower limit of the preset tolerance range of the second preset threshold, it is determined to be a suppression effect, and the processing strategy for conventional monitoring is determined. Wherein, the first preset threshold is greater than the second preset threshold, and the second preset threshold is set to 1.

0.

8. The method for evaluating composite defects in photovoltaic modules according to claim 1, characterized in that, After determining the processing strategy for the corresponding solar cell based on the actual coupling coefficient, the method further includes: Construct a coupling coefficient lookup table, which records the actual coupling coefficient of each defect combination under each severity level combination; Based on the actual coupling coefficients in the coupling coefficient reference table, sort them from high to low, and select the most dangerous defect combinations.

9. A photovoltaic module composite defect evaluation device under long-term outdoor operating conditions, used to perform the photovoltaic module composite defect evaluation method according to any one of claims 1 to 8, characterized in that, include: The imaging inspection module is used to perform imaging inspection on outdoor aged photovoltaic modules to identify the defect types and severity levels of defective cells. The grouping module is used to divide the battery cells into single-defect battery cells and compound-defect battery cells, and further group them according to the defect type and the severity level to obtain multiple single-defect battery cell subgroups and multiple compound-defect battery cell subgroups. The power loss calculation module is used to calculate the single-defect power loss of each of the single-defect battery cell groups and the composite-defect power loss of each of the composite-defect battery cell groups, respectively. The standard coupling coefficient calculation module is used to calculate the standard coupling coefficient for each defect combination based on the power loss of the single defect and the power loss of the composite defect, respectively. The actual coupling coefficient calculation module is used to calculate the actual coupling coefficient based on the standard coupling coefficient and environmental parameters of the actual outdoor working conditions. The processing strategy determination module is used to determine the processing strategy for the corresponding battery cell based on the actual coupling coefficient.

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