A method and system for detecting color difference of thin-film solar cells

Abstract

The present invention discloses a method and system for detecting color difference of thin-film solar cells, the method comprising: collecting an RGB color image of the surface of a thin-film solar cell; converting the RGB color image into a CIE LAB color space image; setting a number of sampling points on the CIE LAB color space image, and calculating the Lab difference between each sampling point and a standard color; using the Lab difference of a sampling point of a certain thin-film solar cell to grade the color difference level of the thin-film solar cell; or / and, using the Lab difference of a sampling point of a certain thin-film solar cell to determine whether the thin-film solar cell has intra-chip color difference. The present invention determines whether a thin-film solar cell has color difference by using the CIE LAB color space, which is more in line with the perception habits of the human eye.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and in particular relates to a method and system for detecting color difference of thin-film solar cells. Background Art

[0002] With the promotion and development of photovoltaic building integration, photovoltaic modules are currently developing from centralized large-scale power stations to distributed forms such as building roofs and facades. Traditional crystalline silicon modules are not as beautiful as thin-film solar modules in building integration applications. In order to make photovoltaic buildings more beautiful, harmonious and practical, thin-film solar cells and modules need to have a higher aesthetics while maintaining a certain power generation efficiency. Color difference is one of the biggest influencing factors, so it is necessary to detect and classify the color difference of photovoltaic modules in order to facilitate the color difference consistency management of photovoltaic modules in the same project and achieve the best project appearance effect.

[0003] like Figure 1 As shown, thin-film solar cells are generally composed of a multilayer film of glass, front electrode (TCO), semiconductor layer (power generation layer), and back electrode (metal film layer / transparent conductive layer). During the production process, they need to go through multiple deposition / coating methods. Large-area coating has the problem of coating uniformity. After the film layers are uniformly stacked, there will be color difference problems on the light-receiving surface of the battery, such as intra-chip color difference and inter-chip color difference.

[0004] Therefore, in the detection stage, a colorimeter or manual visual method is generally used. Similar existing patent applications such as CN219810829U, CN201820959410.2 and CN115931735A all use a colorimeter for detection. However, the colorimeter can only detect one point at a time, and its detection point is small, generally 8-10mm spot. If multiple points are to be detected, the time required will increase exponentially. In addition, the use and maintenance costs of the colorimeter are high, and it cannot perform comprehensive color difference detection on thin-film solar cells and components, and it cannot classify products with different color differences. Its detection efficiency is low and the cost of use remains high.

[0005] Chinese patent application CN201910999565.8 discloses a method for color difference sorting of solar cells, comprising the steps of: S11, taking a sample solar cell and collecting its color image; S12, graying the color image to obtain the gray histogram and average gray value of the three channels of R, G, and B respectively; S13, weighted summing the average gray values ​​of the three channels of R, G, and B to obtain the bin value; S14, repeating steps S11-S13 to obtain the color difference of multiple sample solar cells. data; S15, determine the number of bins of the solar cell and the bin value range corresponding to each bin; S16, find the standard solar cell and the standard histogram in each bin; S21, take the solar cell to be sorted and collect its color image; S22, grayscale the color image to obtain the grayscale histogram of the three channels R, G, and B respectively; S23, compare the grayscale histogram with the standard histogram for similarity, and classify the solar cell into the bin corresponding to the standard histogram with the highest similarity.

[0006] The above-mentioned prior art uses RGB color space for color analysis, which is based on the principle of the three primary colors of light, but is not completely consistent with the way the human eye perceives color. Therefore, it may not be accurate enough when representing color differences and cannot well reflect the human eye's perception of color differences. Summary of the invention

[0007] In view of this, the present invention provides a method and system for detecting color difference of thin-film solar cells, which determines whether there is color difference in thin-film solar cells through CIELAB color space, which is more in line with the perception habits of human eyes. In order to solve the above technical problems, the technical solution of the present invention is to adopt a method for detecting color difference of thin-film solar cells, comprising: Collect RGB color images of the surface of thin-film solar cells; Converting the RGB color image into a CIE LAB color space image; Setting a number of sampling points on the CIE LAB color space image, and calculating the Lab difference between each sampling point and standard white; The color difference level of a thin-film solar cell is graded using the Lab difference of the sampling points of the thin-film solar cell; Or / and, using the Lab difference of the sampling points of a certain thin-film solar cell to determine whether the thin-film solar cell has intra-chip chromatic aberration.

[0008] As an improvement, the steps of collecting the RGB color image of the surface of the thin-film solar cell include: The thin-film solar cells and the surface of the modules are illuminated with a full-spectrum white light source, and the camera forms an image within the threshold angle range. As a further improvement, the wavelength of the full-spectrum white light source is 400nm-700nm, and the threshold angle range is 0°~45°. As another further improvement, the number of sampling points on each film solar cell is 16 and is evenly distributed in a 4×4 pattern.

[0009] As an improvement, the steps of grading the color difference level of a thin-film solar cell by using the Lab difference of the sampling points of the thin-film solar cell include: Calculate the standard deviation of the Lab difference of all sampling points in a thin-film solar cell; Weighting each sampling point in the thin film solar cell based on the standard deviation to obtain a weighted Lab difference; Calculate the chromatic aberration coefficient of the thin film solar cell based on the weighted Lab difference value of each sampling point; When the color difference coefficient of the thin film solar cell is within a certain color difference level, the thin film solar cell is determined to be at the color difference level.

[0010] As an improvement, using the formula σ

[0011] Calculate the standard deviation of the Lab difference of all sampling points in the thin-film solar cell; where σ is the standard deviation, μ is the mean of the Lab difference of each sampling point in the thin-film solar cell, and x i is the Lab difference of sampling point i, n is the number of sampling points; Using the formula S i =x i +aσ Calculate the weighted Lab difference; where S i is the weighted Lab difference of sampling point i, σ is the standard deviation, and a is the weighting coefficient; the weighting coefficient a is 2.5~3.5; Using the formula

[0012] Calculate the color difference coefficient; where, is the color difference coefficient, S i is the weighted Lab difference of sampling point i, and n is the number of sampling points.

[0013] As an improvement, when the color difference coefficient of a certain thin-film solar cell is ≤0, the color difference level of the thin-film solar cell is 0; When the color difference coefficient of a thin film solar cell is in the interval (-0, 0.6], the color difference level of the thin film solar cell is 1; When the color difference coefficient of a certain thin-film solar cell is in the interval (0.6, 1.2], the color difference level of the thin-film solar cell is 2; When the color difference coefficient of a certain thin-film solar cell is in the interval (1.2, 1.8], the color difference level of the thin-film solar cell is 3; When the color difference coefficient of a certain thin-film solar cell is in the interval (1.8, 2.4], the color difference level of the thin-film solar cell is 4; When the color difference coefficient of a certain thin-film solar cell is in the interval (2.4, 3], the color difference level of the thin-film solar cell is 5; When the color difference coefficient of a certain thin-film solar cell is in the interval (3, 3.6], the color difference level of the thin-film solar cell is 6; When the color difference coefficient of a certain thin-film solar cell is greater than 3.6, the color difference level of the thin-film solar cell is 7.

[0014] As an improvement, the step of using the Lab difference of the sampling points of a thin-film solar cell to determine whether the thin-film solar cell has intra-chip chromatic aberration includes: If there are Lab differences of sampling points with opposite signs on a certain thin-film solar cell, it is determined that the thin-film solar cell has intra-chip chromatic aberration; When the Lab difference values ​​of all sampling points of a certain thin-film solar cell are ≥0 or ≤0, the variance of the Lab difference values ​​of all sampling points of the thin-film solar cell is calculated. If the variance is greater than a preset value, it is determined that the certain thin-film solar cell has intra-chip chromatic aberration.

[0015] As an improvement, using the formula -

[0016] Calculate the variance of the Lab difference of all sampling points of the thin-film solar cell; where, is the variance, x i is the Lab difference of sampling point i, μ is the mean of the Lab difference of each sampling point in the thin film solar cell, and n is the number of sampling points.

[0017] The present invention also provides a color difference detection system for thin-film solar cells, which is characterized by comprising: An image acquisition module, used to acquire RGB color images of the surface of thin-film solar cells; A conversion module, used for converting the RGB color image into a CIE LAB color space image; A Lab difference calculation module, used for setting a number of sampling points on the CIE LAB color space image, and calculating the Lab difference between each sampling point and the standard white; A color difference determination module is used to classify the color difference level of a thin-film solar cell by using the Lab difference of the sampling points of the thin-film solar cell; Or / and, using the Lab difference of the sampling points of a certain thin-film solar cell to determine whether the thin-film solar cell has intra-chip chromatic aberration.

[0018] The present invention is beneficial in that: The present invention collects an RGB color image of the surface of a thin-film solar cell, and then converts the RGB color image into a CIE LAB color space image; sets a number of sampling points on the CIE LAB color space image, and calculates the Lab difference between each sampling point and a standard color; finally, uses the Lab difference of the sampling point of a certain thin-film solar cell to grade the color difference level of the thin-film solar cell; or / and, uses the Lab difference of the sampling point of a certain thin-film solar cell to determine whether the thin-film solar cell has intra-chip color difference.

[0019] In the present invention, a full-spectrum white light source is used to illuminate the thin-film solar cell and the surface of the module, and the camera forms an image within a threshold angle range. The wavelength of the full-spectrum white light source is 400nm-700nm, and the threshold angle range is 0°~45°, which is closest to the product color difference state under the natural perception of the human eye.

[0020] In the present invention, CIE LAB color space is used to replace RGB color space for color difference determination. CIE LAB color space is closer to the perception mode of human eyes, can better reflect the color difference, and helps to improve the accuracy of color difference sorting.

[0021] In addition, the present invention can not only classify the color difference of thin-film solar cells and reflect the color difference between thin-film solar cells, but also characterize the color difference within a thin-film solar cell, thereby providing a basis for determining the color difference of a single thin-film solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the structure of a thin-film solar cell.

[0023] Figure 2 This is a flow chart of Example 1 of the present invention.

[0024] Figure 3 Schematic diagram of the distribution of sampling points.

[0025] Figure 4 This is a structural diagram of embodiment 2 of the present invention. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with specific implementation methods.

[0027] Example 1 like Figure 2 As shown, the present invention provides a method for detecting color difference of thin-film solar cells, which uses the CIE LAB color space to determine whether there is intra-chip color difference in thin-film solar cells and to classify the color difference of thin-film solar cells, so as to facilitate subsequent classification and use. The specific steps include: S1 collects RGB color images of the surface of thin-film solar cells.

[0028] In this embodiment, a full-spectrum white light source is used to illuminate the thin-film solar cell and the surface of the module, and the camera forms an image within the threshold angle range. More specifically, the wavelength of the full-spectrum white light source is 400nm-700nm, and the threshold angle range is 0°~45°. After testing, this light source is closest to the color difference state of the product under the natural perception of the human eye.

[0029] S2 converts the RGB color image into a CIE LAB color space image.

[0030] The RGB color space is based on the three basic colors of red (R), green (G), and blue (B), which are superimposed to varying degrees to produce rich and wide-ranging colors.

[0031] The RGB color space can be viewed as a three-dimensional rectangular coordinate system, in which R, G, and B are located on three coordinate axes, black is located at the origin, and white is located at the diagonal point farthest from the origin.

[0032] In the RGB color space, each color can be represented by the coordinates of the three color components red, green, and blue, such as (0,0,0) represents black, (255,255,255) represents white, and so on.

[0033] CIE LAB color space, also known as CIELAB or Lab* color space, is a device-independent color space defined by the International Commission on Illumination (CIE) in 1976. It aims to simulate the human eye's perception of color and provide a unified color description system to facilitate color comparison and conversion in different devices and environments.

[0034] The CIE LAB color space consists of three components: L, a, and b: L (brightness) value: Indicates the lightness or darkness of a color.

[0035] The value range is from 0 to 100, where 0 is completely black and 100 is completely white.

[0036] a (red-green axis) value: Indicates the position of the color between red and green.

[0037] Positive values ​​represent red, negative values ​​represent green.

[0038] The value range is usually -128 to 127 (different software and standards may vary slightly).

[0039] b (yellow-blue axis) value: Indicates the color's position between yellow and blue.

[0040] Positive values ​​represent yellow, negative values ​​represent blue.

[0041] The value range is usually -128 to 127.

[0042] Converting RGB color space to CIE LAB color space usually requires the following steps: 1. Linearize RGB values: First, you need to convert nonlinear RGB values ​​to linear light RGB values. This is because the output of most display devices is nonlinear (i.e. gamma correction), and linear light values ​​need to be used in color space conversion.

[0043] 2. Convert to CIE XYZ color space: Using the linearized RGB values, convert them to CIE XYZ color space through a set of conversion matrices.

[0044] 3. Convert to CIE LAB color space: Finally, use the CIE XYZ values ​​to convert to CIE LAB values.

[0045] Since the conversion of RGB color space into CIE LAB color space is a prior art, it will not be described in detail in the present invention.

[0046] S3 sets a number of sampling points on the CIE LAB color space image, and calculates the Lab difference between each sampling point and the standard color.

[0047] In this embodiment, the number of sampling points can be set according to the size of the surface area of ​​the thin-film solar cell. It can be understood that the more sampling points there are, the more accurate the calculation is, but also consumes more system resources. Therefore, in this embodiment, the number of sampling points on each thin-film solar cell is 16, and they are evenly distributed in a 4×4 format, such as Figure 3 As shown, the red boxes are schematic diagrams of sampling points.

[0048] In order to reflect the difference in color of each sampling point, a standard color needs to be set, and then each sampling point is compared with the standard color to obtain the LAB difference, so that the color difference can be quantified.

[0049] The standard color selected in this embodiment is standard white (ie, the color that a thin-film solar cell should have without color difference), and the LAB value of standard white is L=100, a=0, and b=0.

[0050] In actual application, it is not necessary to calculate the difference of all three values. For example, in the existing process, thin-film solar cells only have red and green color casts, so only the a value is needed.

[0051] The sampling point can be a pixel or a number of pixels. When the sampling point is composed of several pixels, the average of the a values ​​of all pixels can be used to represent the a value of the sampling point. Since the a value of standard white is 0, the LAB difference of the sampling point is actually the a value of the sampling point.

[0052] S4 uses the Lab difference of the sampling points to determine and grade the color difference within the chip.

[0053] In this embodiment, the Lab difference of the sampling points can be used to determine whether there is intra-chip color difference in the thin-film solar cell, and to classify the color difference.

[0054] The so-called intra-chip color difference refers to the color difference between different areas within the same solar cell. Due to the complex manufacturing process of thin-film solar cells, which involves multiple deposition and processing processes, slight changes in these processes may cause uneven colors at different locations on the cell. This unevenness not only affects the appearance of the cell, but may also reflect the inconsistency of the cell performance, because the color difference may be related to factors such as the thickness of the film, the composition of the material, or the crystal quality.

[0055] The color difference between cells refers to the color difference between different cells. This may be due to changes in manufacturing conditions between batches, such as fluctuations in parameters such as temperature, pressure, gas flow, or differences in raw material batches. The existence of color difference between cells will affect the overall appearance uniformity of the component. For some application scenarios with high requirements for aesthetics, such as building-integrated photovoltaics (BIPV), color difference between cells is an important consideration.

[0056] After grading the color difference, the color difference between chips can be quantified, and solar cells with different color difference levels can be used for different scenes.

[0057] Specifically, the steps of grading the color difference level of a thin-film solar cell by using the Lab difference of the sampling points of the thin-film solar cell include: S411 calculates the standard deviation of the Lab differences of all sampling points in a thin film solar cell.

[0058] In this step, we use the formula σ

[0059] Calculate the standard deviation of the Lab difference of all sampling points in the thin-film solar cell; where σ is the standard deviation, μ is the mean of the Lab difference of each sampling point in the thin-film solar cell, and x i is the Lab difference of sampling point i, and n is the number of sampling points.

[0060] S412 weights each sampling point in the thin-film solar cell based on the standard deviation to obtain a weighted Lab difference.

[0061] The color difference between the sampling points is not too large. If the Lab difference is used directly, it is difficult to reflect the color difference between the two sampling points. Therefore, the present invention performs weighted processing on the Lab difference so that the color difference between the sampling points is amplified, thereby facilitating the judgment of the subsequent steps. Specifically, the formula is used in this step S i =x i +aσ Calculate the weighted Lab difference; where S i is the weighted Lab difference of sampling point i, σ is the standard deviation, and a is the weighting coefficient; the weighting coefficient a is 2.5~3.5, which is obtained based on the experience of the technicians.

[0062] S413 calculates the color difference coefficient of the thin film solar cell based on the weighted Lab difference value of each sampling point.

[0063] In this step, we use the formula

[0064] Calculate the color difference coefficient; where, is the color difference coefficient, S i is the weighted Lab difference of sampling point i, and n is the number of sampling points.

[0065] The color difference coefficient is used to quantify the color difference of each thin-film solar cell, so as to facilitate its classification in the subsequent steps. It can be foreseen that the smaller the color difference coefficient, the smaller the color difference of the thin-film solar cell; the larger the color difference coefficient, the greater the color difference of the thin-film solar cell.

[0066] S414: When the color difference coefficient of the thin-film solar cell is at a certain color difference level, the thin-film solar cell is determined to be at the color difference level.

[0067] The color difference levels set in the present invention are shown in Table 1.

[0068] Table 1 Color difference grading table

[0069] Based on Table 1, the classification in this implementation is as follows: When the color difference coefficient of a certain thin-film solar cell is ≤0, the color difference level of the thin-film solar cell is 0; When the color difference coefficient of a thin film solar cell is in the interval (-0, 0.6], the color difference level of the thin film solar cell is 1; When the color difference coefficient of a certain thin-film solar cell is in the interval (0.6, 1.2], the color difference level of the thin-film solar cell is 2; When the color difference coefficient of a certain thin-film solar cell is in the interval (1.2, 1.8], the color difference level of the thin-film solar cell is 3; When the color difference coefficient of a certain thin-film solar cell is in the interval (1.8, 2.4], the color difference level of the thin-film solar cell is 4; When the color difference coefficient of a certain thin-film solar cell is in the interval (2.4, 3], the color difference level of the thin-film solar cell is 5; When the color difference coefficient of a certain thin-film solar cell is in the interval (3, 3.6], the color difference level of the thin-film solar cell is 6; When the color difference coefficient of a certain thin-film solar cell is greater than 3.6, the color difference level of the thin-film solar cell is 7.

[0070] In addition, the steps of setting the color difference grading threshold in this embodiment are: 1. Sample preparation: Randomly select products as test samples. To ensure data accuracy, the number of samples should be ≥ 20. Use a colorimeter to test the color difference of the samples. The number of test points for each sample should be ≥ 9 to obtain the color difference between and within the product.

[0071] 2. Calculate the color difference coefficient of each sample piece using the color difference detection method provided by the present invention.

[0072] 3. The batch of samples is visually observed by human eyes and tested again with a colorimeter. The results of the colorimeter detection equipment, the secondary detection results of the colorimeter, and the visual results of the human eye are compared to determine the range of the color difference coefficient that is difficult for the human eye to distinguish, and the color difference classification / grading standard is obtained, that is, the inter-piece color difference classification threshold range of the color difference detection method of the present invention is obtained.

[0073] In addition, when the coating process changes, resulting in a change in product color, the above operations must be repeated for confirmation and the threshold value must be reset.

[0074] In this step, the step of using the Lab difference of the sampling points of a thin-film solar cell to determine whether the thin-film solar cell has intra-chip chromatic aberration includes: S421 If there are Lab differences of sampling points with opposite signs on a certain thin-film solar cell, it is determined that the thin-film solar cell has intra-chip chromatic aberration.

[0075] That is to say, the Lab difference of the sampling points on a certain thin-film solar cell can be both positive and negative, so it can be directly determined that the thin-film solar cell has intra-chip chromatic aberration.

[0076] S422: when the Lab differences of all sampling points of a thin-film solar cell are ≥0 or ≤0, the variance of the Lab differences of all sampling points of the thin-film solar cell is calculated. If the variance is greater than a preset value, it is determined that the thin-film solar cell has intra-chip chromatic aberration.

[0077] That is to say, if the Lab differences of the sampling points on a certain thin-film solar cell are all ≥0 or ≤0, further judgment is required.

[0078] At this time, using the formula -

[0079] Calculate the variance of the Lab difference of all sampling points of the thin-film solar cell; where, is the variance, x i is the Lab difference of sampling point i, μ is the mean of the Lab difference of each sampling point in the thin film solar cell, and n is the number of sampling points.

[0080] When the variance of the Lab difference values ​​of all sampling points of the thin-film solar cell is greater than a preset value, such as 1, it is determined that the thin-film solar cell has intra-chip chromatic aberration.

[0081] Example 2 like Figure 4 As shown, the present invention also provides a color difference detection system for thin-film solar cells, which is characterized by comprising: An image acquisition module, used to acquire RGB color images of the surface of thin-film solar cells; A conversion module, used for converting the RGB color image into a CIE LAB color space image; A Lab difference calculation module, used for setting a number of sampling points on the CIE LAB color space image, and calculating the Lab difference between each sampling point and the standard white; A color difference determination module is used to classify the color difference level of a thin-film solar cell by using the Lab difference of the sampling points of the thin-film solar cell; Or / and, using the Lab difference of the sampling points of a certain thin-film solar cell to determine whether the thin-film solar cell has intra-chip chromatic aberration.

[0082] In this embodiment, visual inspection is combined with an automated device to automatically complete the detection and classification of the color difference of thin-film solar cells during the transmission process. In the transmission equipment, an image acquisition module including a sensor, a light source, a camera and other devices is set up. When the thin-film solar cell arrives, image acquisition is started, and the image is processed and analyzed using the image acquisition module, the conversion module, the Lab difference calculation module and the color difference judgment module, and the color difference calculation is performed to obtain the color difference data of the battery itself.

[0083] The above are only preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limiting the present invention, and the protection scope of the present invention should be based on the scope defined by the claims. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for detecting color difference of thin-film solar cells, characterized in that include: Collect RGB color images of the surface of thin-film solar cells; Converting the RGB color image into a CIE LAB color space image; Setting a number of sampling points on the CIE LAB color space image, and calculating the Lab difference between each sampling point and the standard color; The color difference level of a thin-film solar cell is graded using the Lab difference of the sampling points of the thin-film solar cell; Or / and, using the Lab difference of the sampling points of a certain thin-film solar cell to determine whether the thin-film solar cell has intra-chip chromatic aberration.

2. A method for detecting color difference of thin-film solar cells according to claim 1, characterized in that The steps of collecting RGB color images of the surface of thin-film solar cells include: The thin-film solar cell and the surface of the component are illuminated with a full-spectrum white light source, and the camera forms an image within a threshold angle range; the wavelength of the full-spectrum white light source is 400nm-700nm, and the threshold angle range is 0°~45°.

3. A method for detecting color difference of thin-film solar cells according to claim 2, characterized in that: The standard color is standard white.

4. The method for detecting color difference of thin-film solar cells according to claim 2, characterized in that: There are 16 sampling points on each film solar cell, and they are evenly distributed in a 4×4 format.

5. The method for detecting color difference of thin-film solar cells according to claim 1, characterized in that The steps of grading the color difference level of a thin-film solar cell by using the Lab difference of the sampling points of the thin-film solar cell include: Calculate the standard deviation of the Lab difference of all sampling points in a thin-film solar cell; Weighting each sampling point in the thin film solar cell based on the standard deviation to obtain a weighted Lab difference; Calculate the chromatic aberration coefficient of the thin film solar cell based on the weighted Lab difference value of each sampling point; When the color difference coefficient of the thin film solar cell is within a certain color difference level, the thin film solar cell is determined to be at the color difference level.

6. A method for detecting color difference of thin-film solar cells according to claim 5, characterized in that: Using the formula s Calculate the standard deviation of the Lab difference of all sampling points in the thin-film solar cell; where σ is the standard deviation, μ is the mean of the Lab difference of each sampling point in the thin-film solar cell, and x i is the Lab difference of sampling point i, n is the number of sampling points; Using the formula S i =x i +aσ Calculate the weighted Lab difference; where S i is the weighted Lab difference of sampling point i, σ is the standard deviation, and a is the weighting coefficient; the weighting coefficient a is 2.5~3.5; Using the formula Calculate the color difference coefficient; where, is the color difference coefficient, S i is the weighted Lab difference of sampling point i, and n is the number of sampling points.

7. The method for detecting color difference of thin-film solar cells according to claim 5, characterized in that: When the color difference coefficient of a certain thin-film solar cell is ≤0, the color difference level of the thin-film solar cell is 0; When the color difference coefficient of a thin film solar cell is in the interval (-0, 0.6], the color difference level of the thin film solar cell is 1; When the color difference coefficient of a certain thin-film solar cell is in the interval (0.6, 1.2], the color difference level of the thin-film solar cell is 2; When the color difference coefficient of a certain thin-film solar cell is in the interval (1.2, 1.8], the color difference level of the thin-film solar cell is 3; When the color difference coefficient of a certain thin-film solar cell is in the interval (1.8, 2.4], the color difference level of the thin-film solar cell is 4; When the color difference coefficient of a certain thin-film solar cell is in the interval (2.4, 3], the color difference level of the thin-film solar cell is 5; In a certain thin film solar cell, the chromatic aberration coefficient is in the range (3, 3.6], the color difference level of the thin film solar cell is 6; When the color difference coefficient of a certain thin-film solar cell is greater than 3.6, the color difference level of the thin-film solar cell is 7.

8. The method for detecting color difference of thin-film solar cells according to claim 1, characterized in that The steps of using the Lab difference of the sampling points of a thin-film solar cell to determine whether the thin-film solar cell has intra-chip chromatic aberration include: If there are Lab differences of sampling points with opposite signs on a certain thin-film solar cell, it is determined that the thin-film solar cell has intra-chip chromatic aberration; When the Lab difference values ​​of all sampling points of a certain thin-film solar cell are ≥0 or ≤0, the variance of the Lab difference values ​​of all sampling points of the thin-film solar cell is calculated. If the variance is greater than a preset value, it is determined that the certain thin-film solar cell has intra-chip chromatic aberration.

9. A method for detecting color difference of thin-film solar cells according to claim 8, characterized in that: Using the formula - Calculate the variance of the Lab difference of all sampling points of the thin-film solar cell; where, is the variance, x i is the Lab difference of sampling point i, μ is the mean of the Lab difference of each sampling point in the thin film solar cell, and n is the number of sampling points.

10. A color difference detection system for thin-film solar cells, characterized in that include: An image acquisition module, used to acquire RGB color images of the surface of thin-film solar cells; A conversion module, used for converting the RGB color image into a CIE LAB color space image; A Lab difference calculation module, used for setting a number of sampling points on the CIE LAB color space image, and calculating the Lab difference between each sampling point and the standard white; A color difference determination module is used to classify the color difference level of a thin-film solar cell by using the Lab difference of the sampling points of the thin-film solar cell; Or / and, using the Lab difference of the sampling points of a certain thin-film solar cell to determine whether the thin-film solar cell has intra-chip chromatic aberration.

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