Solar cell el detection method

Abstract

The application discloses a solar cell EL detection method, comprising: acquiring a cell EL image; identifying whether the cell EL image has a concentric circle; analyzing the concentric circle of the cell EL image; classifying the cell EL image; verifying whether there is a hot spot after a photovoltaic module is prepared by using the cell classified by the concentric circle; determining that the concentric circle type of the photovoltaic module without the hot spot is a first type of concentric circle, and the corresponding cell is a qualified cell; and determining that the concentric circle type of the photovoltaic module with the hot spot is a second type of concentric circle, and the corresponding cell is an unqualified cell. Through detailed classification of the concentric circle, whether there is a hot spot is verified according to the cell classified by the concentric circle, a concentric circle classification standard is formulated according to the classification method and actual verification effect, and the problem of excessive quality caused by excessively strict concentric circle determination standard is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of single crystal silicon cell production, and more particularly to a solar cell EL detection method. BACKGROUND

[0002] In the production process of a straight pull silicon rod, the crystal directional solidification time is shortened, the melt latent heat release is mismatched with the thermal field temperature gradient, the crystal growth rate is accelerated, and excessive thermal stress can cause dislocation defects in the silicon wafer, which can easily produce black heart cell pieces. Based on the principle of electroluminescence (EL), the method of near-infrared detection can detect hidden defects in crystalline silicon solar cells and modules. In the EL imaging of the black heart cell piece, concentric circles gradually brightening from the center of the cell piece to the edge can be clearly seen, so that the part of the defect shows weak or no light emission in the EL test process, thereby forming a composite dense area, and the cell piece center presents a black area under the condition of power-on.

[0003] Currently, the equipment can automatically determine whether the EL image has concentric circles, but the types of concentric circles are not classified, so that some slight concentric circles are also determined as harmful concentric circles. In actual use, some slight concentric circles do not affect the use efficiency and reliability, and there is a problem of excessive quality caused by too strict determination standard.

[0004] Therefore, it is urgent to provide a solar cell EL detection method capable of classifying concentric circles in a cell EL image. SUMMARY

[0005] Therefore, the present application provides a solar cell EL detection method, which comprises the following steps:

[0006] obtaining an EL image of a cell piece;

[0007] identifying whether the EL image of the cell piece has concentric circles, when the EL image of the cell piece includes at least one concentric circle, the EL image of the cell piece includes a concentric circle region and a first region other than the concentric circle region;

[0008] analyzing the concentric circles in the EL image of the cell piece, including: extracting the diameter of the concentric circles in the EL image of the cell piece, calculating the area ratio of the concentric circles, and obtaining the ratio of the gray value of the concentric circle region to the gray value of the first region;

[0009] classifying the EL image of the cell piece, including: classifying the concentric circles according to the diameter of the concentric circles in the EL image of the cell piece, the area ratio of the concentric circles, and the ratio of the gray value of the concentric circle region to the gray value of the first region, respectively;

[0010] Verify whether there is hot spot after the battery piece classified by concentric circles is made into a photovoltaic module;

[0011] Determine the concentric circle type of the photovoltaic module without hot spot as a first type of concentric circle, and the corresponding battery piece as a qualified battery piece, and determine the concentric circle type of the photovoltaic module with hot spot as a second type of concentric circle, and the corresponding battery piece as an unqualified battery piece.

[0012] Optionally, the concentric circles in the battery piece EL image have a width along the diameter direction, and the inner diameter and the outer diameter of the concentric circles in the battery piece EL image are extracted in pixel value units.

[0013] Optionally, the area ratio of the concentric circles in the battery piece EL image includes: extracting the area of the concentric circle region in pixel value units, the area of the concentric circle region being the sum of the areas of at least one concentric circle, extracting the total area of the battery piece, and dividing the extracted area of the concentric circle region by the total area of the battery piece to obtain the area ratio of the concentric circles in the battery piece EL image.

[0014] Optionally, the concentric circles in the battery piece EL image have a width along the diameter direction, and the concentric circles include an inner diameter and an outer diameter, and the area of any concentric circle in the battery piece EL image is the area of the circle with the outer diameter of the concentric circle minus the area of the circle with the inner diameter of the concentric circle.

[0015] Optionally, the ratio of the gray value of the concentric circle region to the gray value of the first area in the battery piece EL image includes extracting the gray value of the concentric circle region, extracting the gray value of the first area, and dividing the extracted gray value of the concentric circle region by the gray value of the first area to obtain the ratio of the gray value of the concentric circle region to the gray value of the first area in the battery piece EL image.

[0016] Optionally, the concentric circles classified according to the diameter of the concentric circles in the battery piece EL image, the area ratio of the concentric circles, and the ratio of the gray value of the concentric circle region to the gray value of the first area include slight concentric circles and severe concentric circles.

[0017] Optionally, in the slight concentric circles, the diameter of the concentric circle with the largest outer diameter is greater than 0 and less than 20px, the area ratio of the concentric circle is greater than 0 and less than 5%, and the ratio of the gray value of the concentric circle region to the gray value of the first area is greater than 95% and less than 100%.

[0018] Optionally, in the severe concentric circles, the diameter of the concentric circle with the smallest inner diameter is not less than 20px, the area ratio of the concentric circle is not less than 5%, and the ratio of the gray value of the concentric circle region to the gray value of the first area is not greater than 95%.

[0019] Optionally, when the battery piece EL image does not have concentric circles, the corresponding battery piece is a qualified battery piece.

[0020] Optionally, when the battery piece EL image does not have the concentric circle, the diameter of the concentric circle in the battery piece EL image is 0px, the area ratio of the concentric circle is 0, and the ratio of the gray value of the concentric circle region to the gray value of the first region is 100%.

[0021] Compared with the prior art, the solar cell piece EL detection method provided by the application at least achieves the following beneficial effects:

[0022] The application provides a solar cell piece EL detection method, which comprises the following steps: acquiring an EL image of a battery piece; identifying whether the EL image of the battery piece has a concentric circle; when the EL image of the battery piece comprises at least one concentric circle, the EL image of the battery piece comprises a concentric circle region and a first region except the concentric circle region; analyzing the concentric circle of the EL image of the battery piece, comprising: extracting the diameter of the concentric circle in the EL image of the battery piece, calculating the area ratio of the concentric circle, and obtaining the ratio of the gray value of the concentric circle region to the gray value of the first region; classifying the EL image of the battery piece, comprising: classifying the concentric circle according to the diameter of the concentric circle in the EL image of the battery piece, the area ratio of the concentric circle and the ratio of the gray value of the concentric circle region to the gray value of the first region, respectively; verifying whether there is a hot spot after a photovoltaic module is prepared from the battery piece classified according to the concentric circle; determining that the concentric circle type of the photovoltaic module without a hot spot is a type I concentric circle, and the corresponding battery piece is a qualified battery piece; and determining that the concentric circle type of the photovoltaic module with a hot spot is a type II concentric circle, and the corresponding battery piece is an unqualified battery piece. The concentric circle is classified based on the diameter of the concentric circle in the EL image of the battery piece, the area ratio of the concentric circle and the ratio of the gray value of the concentric circle region to the gray value of the first region, it is verified whether the module prepared from the battery piece classified according to the concentric circle has a hot spot, the concentric circle classification standard is formulated according to the verification effect and the classification method, and in the production process of monocrystalline silicon battery pieces, the type I concentric circle type battery piece which does not affect the efficiency of the module can be separated, and the problem of excessive quality caused by excessively strict concentric circle determination standard is solved.

[0023] Of course, implementing any product of the present application does not necessarily need to achieve all the technical effects described above at the same time.

[0024] Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments thereof, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings incorporated in and forming a part of the specification, illustrate embodiments of the present application and, together with the description, serve to explain the principles of the application.

[0026] Figure 1is a flow chart of a solar cell EL detection method provided by the present application;

[0027] Figure 2 is a solar cell EL image schematic diagram with concentric circles;

[0028] Figure 3 is a solar cell EL image schematic diagram without concentric circles;

[0029] 1-concentric circle area, 2-first area, d-inner diameter, D-outer diameter. DETAILED DESCRIPTION

[0030] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of the components and steps set forth in the examples, numerical expressions, and numerical values, unless specifically stated otherwise, do not limit the scope of the present application.

[0031] The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the scope of the application its application or uses.

[0032] Techniques, methods, and devices known to those of ordinary skill in the relevant art can not be discussed in detail herein. However, where appropriate, such techniques, methods, and devices can be considered part of the specification.

[0033] In all of the examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments can have different values.

[0034] It should be noted that like reference numerals and letters refer to like items in the following drawings, and thus, once an item is defined in one drawing, it need not be discussed further in subsequent drawings.

[0035] Referring to the drawings Figure 1 , Figure 2 The present application provides a solar cell EL detection method, comprising the steps of:

[0036] S1 obtaining an EL image of a solar cell;

[0037] S2 identifying whether the EL image of the solar cell has concentric circles, when the EL image of the solar cell includes at least one concentric circle, the EL image of the solar cell includes a concentric circle area 1 and a first area 2 other than the concentric circle area 1;

[0038] S3 analyzing the concentric circles of the EL image of the solar cell, comprising: extracting the diameter of the concentric circles in the EL image of the solar cell, calculating the area ratio of the concentric circles, and obtaining the ratio of the gray value of the concentric circle area 1 to the gray value of the first area 2;

[0039] S4 classifies the battery piece EL image, including: classifying the concentric circles according to the diameter of the concentric circles in the battery piece EL image, the area proportion of the concentric circles, and the ratio of the gray value of the concentric circle region 1 to the gray value of the first region 2, respectively;

[0040] S5 verifies whether there is a hot spot in the photovoltaic module prepared by the battery piece after the concentric circle classification;

[0041] S6 determines that the concentric circle type without a hot spot in the photovoltaic module is a first type of concentric circle, and the corresponding battery piece is a qualified battery piece, and determines that the concentric circle type with a hot spot in the photovoltaic module is a second type of concentric circle, and the corresponding battery piece is an unqualified battery piece.

[0042] It should be noted that after S1 obtains the battery piece EL image, S2 identifies whether the battery piece EL image has concentric circles based on the computer vision system. When the battery piece EL image does not have concentric circles, the corresponding battery piece is a qualified battery piece. When the battery piece EL image has concentric circles, S3 continues to analyze the concentric circles: extracts the diameter of the concentric circles in the battery piece EL image, calculates the area proportion of the concentric circles, and obtains the ratio of the gray value of the concentric circle region 1 to the gray value of the first region 2. S4 classifies the concentric circles according to the above three indexes. S5 verifies whether there is a hot spot in the module prepared by the battery piece according to the concentric circle classification. Because when there is a defective area in the series branch of the power generation state photovoltaic module, the area is treated as a load, consumes the energy generated by other areas, causes local overheating, and the photovoltaic module will have a hot spot, which reduces the output power of the module to a certain extent and even causes local burning and permanent damage of the photovoltaic module, which is an important factor affecting the output power and service life of the photovoltaic module. According to the verification effect and the classification method, a concentric circle classification standard is formulated. S6 determines that the concentric circle type without a hot spot in the photovoltaic module is a first type of concentric circle, and the corresponding battery piece is a qualified battery piece, and determines that the concentric circle type with a hot spot in the photovoltaic module is a second type of concentric circle, and the corresponding battery piece is an unqualified battery piece.

[0043] It can be understood that in the production process of monocrystalline silicon battery pieces, according to the new concentric circle classification standard, specifically, the battery pieces can be divided into: no concentric circle battery piece, first type of concentric circle battery piece, and second type of concentric circle battery piece. The no concentric circle battery piece and the first type of concentric circle battery piece are both qualified battery pieces, and the second type of concentric circle battery piece is an unqualified battery piece. The new classification method can separate the first type of concentric circle battery piece which does not affect the efficiency of the module, and avoid classifying the first type of concentric circle battery piece and the second type of concentric circle battery piece as harmful concentric circle battery pieces, and solve the problem of excessive quality caused by the current too strict concentric circle determination standard.

[0044] In some optional embodiments, continuing to refer to the accompanying drawings Figure 2, the concentric circle in the battery piece EL image has a width along the diameter direction, and the inner diameter d and the outer diameter D of the concentric circle in the battery piece EL image are extracted in pixel value units.

[0045] Since the EL image is a dot matrix in the computer-generated digital image, the pixel is the basic unit of the dot matrix, and it is more convenient to extract the inner diameter d and the outer diameter D of the concentric circle in the battery piece EL image in pixel value units rather than in centimeters based on the computer vision system. The inner diameter d and the outer diameter D of the concentric circle in the battery piece EL image are further used to calculate the area of the concentric circle and as one of the indicators for classifying the concentric circle.

[0046] In some optional embodiments, continuing to refer to the accompanying Figure 2 , the area ratio of the concentric circle in the battery piece EL image includes: extracting the area of the concentric circle region 1 in pixel value units, the area of the concentric circle region 1 is the sum of the areas of at least one concentric circle, extracting the total area of the battery piece, and dividing the extracted area of the concentric circle region 1 by the total area of the battery piece to obtain the area ratio of the concentric circle in the battery piece EL image.

[0047] According to the area ratio of the concentric circle in the battery piece EL image obtained by dividing the extracted area of the concentric circle region 1 by the total area of the battery piece, the accompanying Figure 2 In the accompanying drawings, only one concentric circle is taken as an example, for example, the pixel value of the battery piece is 1820px, the inner diameter d of the concentric circle is 1400px, the outer diameter D of the concentric circle is 1450px, the area of the concentric circle is 447450, the area of the battery piece is 3312400, and the proportion of the pixel value of the battery piece is 13.508%. Therefore, it can be clearly known that the proportion of the defect area in the battery piece and the defect degree of the battery piece are understood, which is one of the important indicators for classifying the concentric circle.

[0048] In some optional embodiments, continuing to refer to the accompanying Figure 2 , the concentric circle in the battery piece EL image has a width along the diameter direction, and the inner diameter d and the outer diameter D of the concentric circle in the battery piece EL image are extracted in pixel value units.

[0049] The inner diameter d and the outer diameter D of the concentric circle in the battery piece EL image extracted in pixel value units can calculate the area of any concentric circle, and further can calculate the area ratio of the concentric circle in the battery piece EL image.

[0050] In some optional embodiments, continuing to refer to the accompanying Figure 2, the extracting the ratio of the gray value of the concentric circular area 1 to the gray value of the first area 2 in the EL image of the battery piece includes extracting the gray value of the concentric circular area 1, extracting the gray value of the first area 2, and dividing the gray value of the concentric circular area 1 by the gray value of the first area 2 to obtain the ratio of the gray value of the concentric circular area 1 to the gray value of the first area 2 in the EL image of the battery piece.

[0051] It should be noted that the white color and the black color are divided into several levels according to the logarithmic relationship, which is called "gray level", and the range is from 0 to 255, white is 255, and black is 0. For example, the extracted gray value of the concentric circular area 1 is 180, and the extracted gray value of the first area 2 is 230. Then the gray value of the concentric circular area 1 / gray value of the first area 2 = 78.26%, and the smaller the ratio is, the greater the difference between the concentric circular area 1 and the first area 2 is, which is easy to affect the overall power of the prepared component.

[0052] In some optional embodiments, continuing to refer to the accompanying Figure 2 , the concentric circles classified according to the diameter of the concentric circle, the area ratio of the concentric circle, and the ratio of the gray value of the concentric circular area 1 to the gray value of the first area 2 in the EL image of the battery piece include slight concentric circles and serious concentric circles.

[0053] The concentric circles classified according to the diameter of the concentric circle, the area ratio of the concentric circle, and the ratio of the gray value of the concentric circular area 1 to the gray value of the first area 2 in the EL image of the battery piece include slight concentric circles and serious concentric circles. The concentric circles are classified according to the above three indexes instead of being classified as harmful concentric circles, and whether the battery piece prepared by the slight concentric circles and the serious concentric circles has a hot spot is verified, so that the concentric circle type which does not affect the efficiency of the battery piece is separated, and a basis for a new concentric circle classification standard is provided.

[0054] In some optional embodiments, continuing to refer to the accompanying Figure 2 , the diameter of the concentric circle with the largest outer diameter D in the slight concentric circle is greater than 0 and less than 20px, the area ratio of the concentric circle is greater than 0 and less than 5%, and the ratio of the gray value of the concentric circular area 1 to the gray value of the first area 2 is greater than 95% and less than 100%.

[0055] It can be understood that when the diameter of the concentric circle with the largest outer diameter D in the concentric circle is greater than 0 and less than 20px, the diameter of the concentric circle is small, the area ratio of the corresponding concentric circle is greater than 0 and less than 5%, the area occupied by the concentric circle is small, and the ratio of the gray value of the concentric circular area 1 to the gray value of the first area 2 is greater than 95% and less than 100%, it indicates that the difference between the concentric circular area 1 and the first area 2 is small, and such concentric circles are defined as slight concentric circles.

[0056] In some optional embodiments, continuing to refer to the accompanying Figure 2, the diameter of the concentric circle with the minimum inner diameter d in the serious concentric circle is not less than 20px, the area ratio of the concentric circle is not less than 5%, and the ratio of the gray value of the concentric circle region 1 to the gray value of the first region 2 is not greater than 95%.

[0057] It can be understood that when the diameter of the concentric circle with the maximum outer diameter D is not less than 20px, the diameter of the optional concentric circle is greater than or equal to 20px, the concentric circle has a larger diameter, the area ratio of the corresponding concentric circle is not less than 5%, the area occupied by the concentric circle is larger, and the ratio of the gray value of the concentric circle region 1 to the gray value of the first region 2 is not greater than 95%, which indicates that the difference between the concentric circle region 1 and the first region 2 is large, and such concentric circle is defined as a serious concentric circle.

[0058] In some optional embodiments, referring to the accompanying drawings Figure 3 When the battery piece EL image does not have a concentric circle, the corresponding battery piece is a qualified battery piece.

[0059] It can be understood that the EL detection method can detect the hidden defects in the crystalline silicon solar cell and the assembly. The concentric circles gradually brightening from the center of the battery piece to the edge can be clearly seen in the EL imaging image of the black heart battery piece, so that the part with defects shows weak or no light emission in the EL test process, thereby forming a recombination dense area. Under the condition of power on, the center of the battery piece presents a black area. When the battery piece EL image does not have a concentric circle, it indicates that the battery piece has no defects, and the corresponding battery piece is a qualified battery piece.

[0060] In some optional embodiments, continuing to refer to the accompanying drawings Figure 3 When the battery piece EL image does not have a concentric circle, the diameter of the concentric circle in the battery piece EL image is 0px, the area ratio of the concentric circle is 0, and the ratio of the gray value of the concentric circle region 1 to the gray value of the first region 2 is 100%.

[0061] It can be understood that since the battery piece EL image does not have a concentric circle, the diameter of the extracted concentric circle is 0px, the area ratio of the calculated concentric circle is 0, and the ratio of the gray value of the extracted concentric circle region 1 to the gray value of the first region 2 is 100%.

[0062] It can be understood that since the battery piece EL image does not have a concentric circle, the diameter of the extracted concentric circle is 0px, the area ratio of the calculated concentric circle is 0, and the ratio of the gray value of the extracted concentric circle region 1 to the gray value of the first region 2 is 100%.

[0063] The application provides a solar cell EL detection method, comprising the steps of: acquiring a cell EL image; identifying whether the cell EL image has a concentric circle; when the cell EL image comprises at least one concentric circle, the cell EL image comprises a concentric circle area and a first area other than the concentric circle area; analyzing the concentric circle of the cell EL image, comprising: extracting the diameter of the concentric circle in the cell EL image, calculating the area ratio of the concentric circle, and obtaining the ratio of the gray value of the concentric circle area to the gray value of the first area; classifying the cell EL image, comprising: classifying the concentric circle according to the diameter of the concentric circle in the cell EL image, the area ratio of the concentric circle and the ratio of the gray value of the concentric circle area to the gray value of the first area, respectively; verifying whether there is a hot spot in a photovoltaic module prepared by the cell after the concentric circle classification; determining that the concentric circle type of the photovoltaic module without a hot spot is a type of concentric circle, and the corresponding cell is a qualified cell; and determining that the concentric circle type of the photovoltaic module with a hot spot is a type of concentric circle, and the corresponding cell is an unqualified cell. The application classifies the concentric circle based on the diameter of the concentric circle in the cell EL image, the area ratio of the concentric circle and the ratio of the gray value of the concentric circle area to the gray value of the first area, verifies whether the module prepared by the cell classified according to the concentric circle has a hot spot, formulates a concentric circle classification standard according to the verification effect and the classification method, and separates the type of cell with a slight concentric circle which does not affect the efficiency of the module in the monocrystalline silicon cell production process, thereby solving the problem of excessive quality caused by the excessively strict concentric circle determination standard.

[0064] Although some specific embodiments of the application have been described in detail above, those skilled in the art should understand that the above examples are only for illustration, and are not intended to limit the scope of the application. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the application. The scope of the application is defined by the appended claims.

Claims

1. A method for detecting the electroluminescence (EL) of a solar cell, characterized in that, Including the following steps: Acquire EL images of the solar cells; Identify whether the EL image of the battery cell has concentric circles. When the EL image of the battery cell includes at least one concentric circle, the EL image of the battery cell includes a concentric circle region and a first region other than the concentric circle region. The analysis of concentric circles in the EL image of the battery cell includes: extracting the diameter of the concentric circles in the EL image of the battery cell, calculating the area ratio of the concentric circles, and obtaining the ratio of the gray value of the concentric circle region to the gray value of the first region. The classification of the battery cell EL image includes: classifying the concentric circles according to the diameter of the concentric circles, the area ratio of the concentric circles, and the ratio of the gray value of the concentric circle region to the gray value of the first region in the battery cell EL image; Verify whether hot spots exist after the solar cells, which have been classified by concentric circles, are used to manufacture photovoltaic modules; The concentric circles of the photovoltaic module without hot spots are classified as Class I concentric circles, and the corresponding solar cells are qualified solar cells. The concentric circles of the photovoltaic module with hot spots are classified as Class II concentric circles, and the corresponding solar cells are unqualified solar cells.

2. The solar cell EL detection method according to claim 1, characterized in that, The concentric circles in the EL image of the battery cell have a width along the diameter direction. The inner and outer diameters of the concentric circles in the EL image of the battery cell are extracted in pixels.

3. The solar cell EL detection method according to claim 1, characterized in that, Extracting the area ratio of concentric circles in the EL image of the battery cell includes: extracting the area of ​​the concentric circle region in units of pixel value, wherein the area of ​​the concentric circle region is the sum of the areas of at least one concentric circle; extracting the total area of ​​the battery cell; and dividing the extracted area of ​​the concentric circle region by the total area of ​​the battery cell to obtain the area ratio of concentric circles in the EL image of the battery cell.

4. The solar cell EL detection method according to claim 3, characterized in that, The concentric circles in the EL image of the battery cell have a width along the diameter direction. The concentric circles include an inner diameter and an outer diameter. The area of ​​any concentric circle in the EL image of the battery cell is the area of ​​the circle containing the outer diameter of the concentric circle minus the area of ​​the circle containing the inner diameter of the concentric circle.

5. The solar cell EL detection method according to claim 1, characterized in that, Extracting the ratio of the gray values ​​of the concentric circle region to the gray values ​​of the first region in the EL image of the battery cell includes extracting the gray values ​​of the concentric circle region, extracting the gray values ​​of the first region, and dividing the extracted gray values ​​of the concentric circle region by the gray values ​​of the first region to obtain the ratio of the gray values ​​of the concentric circle region to the gray values ​​of the first region in the EL image of the battery cell.

6. The solar cell EL detection method according to claim 2, characterized in that, Concentric circles, classified according to the diameter of the concentric circles in the EL image of the battery cell, the area ratio of the concentric circles, and the ratio of the gray value of the concentric circle region to the gray value of the first region, include slightly concentric circles and severely concentric circles.

7. The solar cell EL detection method according to claim 6, characterized in that, The diameter of the concentric circle with the largest outer diameter is greater than 0 and less than 20px; the area ratio of the concentric circle is greater than 0 and less than 5%; and the ratio of the gray value of the concentric circle region to the gray value of the first region is greater than 95% and less than 100%.

8. The solar cell EL detection method according to claim 6, characterized in that, The diameter of the concentric circle with the smallest inner diameter in the severe concentric circles is not less than 20px, the area ratio of the concentric circle is not less than 5%, and the ratio of the gray value of the concentric circle region to the gray value of the first region is not greater than 95%.

9. The solar cell EL detection method according to claim 1, characterized in that, When the EL image of the battery cell does not have concentric circles, the corresponding battery cell is a qualified battery cell.

10. The solar cell EL detection method according to claim 9, characterized in that, When the EL image of the battery cell does not have concentric circles, the diameter of the concentric circles in the EL image of the battery cell is 0px, the area ratio of the concentric circles is 0, and the gray value ratio of the concentric circle region to the gray value ratio of the first region is 100%.

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