A method for testing the spatial resolution of a photoluminescence defect detector for photovoltaics

Abstract

The application provides a kind of photovoltaic photoluminescence defect detector spatial resolution test method, a series of spatial resolution test boards are used for testing, each test board corresponds to different spatial resolution;Each test board is made of opaque material, the whole is (20-50) mm x (20-50) mm square, is provided with spatial resolution mark, diamond positioning line frame and n hollow rectangle (n>=2);Test position is the center of the required test area of photovoltaic photoluminescence defect detector and four corners;The test method of the application uses the spatial resolution test board of the application to test the spatial resolution of the center of the required test area of photovoltaic photoluminescence defect detector and four corners under different angles, and finally realizes the evaluation of the spatial resolution of photovoltaic photoluminescence defect detector imaging system.

Description

[Technical Field]

[0001] This invention relates to a photoluminescence defect detector for photovoltaic applications, and more specifically, to a method for testing the spatial resolution of the photoluminescence defect detector for photovoltaic applications. [Background Technology]

[0002] Photoluminescence (PL) defect detectors for photovoltaics work by exciting solar cells or silicon wafers with light of a specific wavelength, causing them to emit light of that wavelength. Filters and photosensitive elements capture the light signals emitted by the solar cells or silicon wafers, which are then processed by a computer and displayed on a screen. This allows for the detection of defects in solar cells or silicon wafers that are invisible to the naked eye. A schematic diagram of its principle is shown below. Figure 1 As shown. The imaging system is one of the most critical components of a photoluminescence defect detector for photovoltaics, and currently there are no performance evaluation methods or devices for this type of equipment.

[0003] A similar method is the spatial resolution test method in the international standard ISO 12233 Photography—Electronic still picture imaging—Resolution and spatial frequency responses and CIPA DC-003 Resolution Measurement Methods for Digital Cameras, which uses a test board specifically designed for digital cameras (such as...). Figure 2 As shown), the test board contains a series of wedge-shaped patterns, such as Figure 3 As shown, the pattern consists of five equally spaced black lines of equal width (the spacing is equal to the width of the black lines). The black lines and the spacing decrease from wide to narrow to form a wedge-shaped pattern. When a position where the five black lines cannot be counted is found by visual inspection or a dedicated algorithm, the corresponding spatial resolution is the spatial resolution of the camera.

[0004] Another similar method is the calibration method for the imaging system of the photovoltaic module electroluminescence defect detector, the principle of which is as follows: Figure 4 As shown, the electroluminescence defect detector works by energizing the positive and negative electrodes of a photovoltaic module, causing the module to emit infrared light, which is then captured by a CCD or infrared camera. The light signal is processed by a computer to form an image. It employs a specially designed spatial resolution test board, such as... Figure 5As shown, the test board has a series of six equally spaced, equally sized hollow rectangles arranged at intervals (the interval is equal to the width of the hollow). The spatial resolution test board is pasted on the test position of the photovoltaic module. The light emitted by the electroluminescence of the photovoltaic module is used as the background light. Through the hollow positions in the test board, a series of equally spaced and equally sized line pairs with varying densities are formed. The spatial resolution corresponding to the pattern where five black lines can be counted is found by visual inspection. This spatial resolution is the spatial resolution of the photovoltaic module electroluminescence defect detector at that position.

[0005] However, the above two methods are not suitable for performance evaluation of photoluminescence defect detectors. This is because the maximum test area of ​​current photovoltaic photoluminescence defect detectors is generally 210mm*210mm. The imaging performance of the central area and the surrounding areas of such equipment typically differs (generally, the center is better and the corners are worse). To objectively evaluate the imaging performance of PL equipment, it is necessary to test and evaluate both the center and the surrounding areas. Furthermore, the two methods mentioned above are for digital cameras and photovoltaic module electroluminescence defect detectors, respectively. The spatial resolution test area images (wedge patterns, line-pair images) on their test boards are too large for photovoltaic photoluminescence defect detectors, making it impossible to accurately evaluate the specific location of defects. [Summary of the Invention]

[0006] Therefore, the technical problem to be solved by the present invention is to provide a method for testing the spatial resolution of a photovoltaic photoluminescence defect detector. By reducing the size of the spatial resolution plate and adding positioning lines, the spatial resolution at different angles can be obtained, and finally the spatial resolution of the imaging system of the photovoltaic photoluminescence defect detector can be evaluated.

[0007] To achieve the aforementioned objectives, this invention provides a method for testing the spatial resolution of a photovoltaic photoluminescence defect detector. The method employs a series of spatial resolution test boards, each corresponding to a different spatial resolution. Each test board is made of an opaque material and is a square measuring (20-50) mm × (20-50) mm. Each test board has a spatial resolution mark, a rhombus positioning frame, and n hollow rectangles, where n ≥ 2. The spatial resolution mark is located at one corner of the square. The rhombus positioning frame is inscribed in the midpoints of each side of the square. Each hollow rectangle has the same length and width, and the distance between two adjacent rectangles is equal to the width of the rectangle. The width and spacing of each hollow rectangle are determined by the spatial resolution corresponding to the test board, satisfying the relationship Rs = 1 / 2d, where Rs is the spatial resolution and d is the rectangle spacing and width.

[0008] The method for testing spatial resolution includes the following steps:

[0009] S1. Determine the test location as the center and four corners of the required test area for the photovoltaic photoluminescence defect detector;

[0010] S2. Place the spatial resolution test board with the minimum spatial resolution in different test positions in sequence; set the spatial resolution test board as the first test angle, place solar cells or silicon wafers under the spatial resolution test board, and use the image spatial resolution test method to determine the spatial resolution corresponding to different test positions at the first test angle.

[0011] S3. Rotate the spatial resolution test board to the second test angle and place it in different test positions in sequence. Place solar cells or silicon wafers under the spatial resolution test board and use the image spatial resolution test method to determine the spatial resolution corresponding to the different test positions at the second test angle.

[0012] S4. Rotate the spatial resolution test board to the third test angle and place it in different test positions in sequence. Place solar cells or silicon wafers under the spatial resolution test board and use the image spatial resolution test method to determine the spatial resolution corresponding to each test position at the third test angle.

[0013] S5. Rotate the spatial resolution test board to the fourth test angle and place it in different test positions in sequence. Place solar cells or silicon wafers under the spatial resolution test board and use the image spatial resolution test method to determine the spatial resolution corresponding to each test position at the fourth test angle.

[0014] S6. After obtaining the spatial resolution at different tilt angles at all test positions, the lowest spatial resolution value among all test positions at the same test angle is the spatial resolution of the photovoltaic photoluminescence defect detector under test at that test angle.

[0015] The image spatial resolution test method determines the spatial resolution of the test position at the corresponding test angle as follows: First, use a spatial resolution test board with the lowest spatial resolution and take an image with a photovoltaic photoluminescence defect detector. The image is a striped image with alternating bright and dark lines. By visual inspection, if n-1 black lines can be counted (n is the number of hollow rectangles on the spatial resolution test board), then replace it with a test board with a higher spatial resolution. Continue until n-1 black lines cannot be counted on the image. The spatial resolution corresponding to the previous spatial resolution test board is the spatial resolution of the test position at the corresponding test angle.

[0016] The advantages of this invention are as follows: By setting up a series of spatial resolution test boards, each corresponding to a different spatial resolution, the size of the spatial resolution test boards is reduced, facilitating testing at different test positions such as the center and four corners of the required test area. Simultaneously, positioning lines are added to the spatial resolution test boards to facilitate positioning at 45° and -45° test angles, thereby obtaining spatial resolution at different angles. In terms of testing method, tests are performed separately at the center and four corners of the required test area for the photovoltaic photoluminescence defect detector, and each test position is tested at a different test angle. This allows for the measurement of the spatial resolution of the photovoltaic photoluminescence defect detector at different positions and angles. Ultimately, this enables the evaluation of the spatial resolution of the photovoltaic photoluminescence defect detector imaging system, filling the gap in existing technologies that cannot accurately evaluate the specific location of the photovoltaic photoluminescence defect detector. [Attached Image Description]

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] Figure 1 This is a schematic diagram of the existing photovoltaic photoluminescence measurement principle.

[0019] Figure 2 This is a schematic diagram of the structure of an existing digital camera-specific test board.

[0020] Figure 3 This is a schematic diagram of a wedge-shaped pattern on an existing digital camera-specific test board.

[0021] Figure 4 This is a schematic diagram of the measurement principle of an existing electroluminescence defect detector.

[0022] Figure 5 This is a schematic diagram of the structure of an existing spatial resolution test panel.

[0023] Figure 6 This is a schematic diagram of the spatial resolution test board of the present invention.

[0024] Figure 7 This is a schematic diagram showing the distribution of test positions in the required test area of ​​the photovoltaic photoluminescence defect detector of the present invention.

[0025] Figure 8 This is a flowchart of the spatial resolution testing method of the photovoltaic photoluminescence defect detector of the present invention.

Detailed Implementation Methods

[0026] This invention provides a method for testing the spatial resolution of a photovoltaic photoluminescence defect detector. By reducing the size of the spatial resolution board and adding positioning lines, spatial resolution at different angles can be obtained, ultimately achieving an evaluation of the spatial resolution of the photovoltaic photoluminescence defect detector imaging system.

[0027] The technical solution in this invention aims to solve the aforementioned problems. The overall approach is as follows: By setting up a series of spatial resolution test boards, each corresponding to a different spatial resolution, the size of the test boards is reduced. This facilitates testing at different test positions, such as the center and four corners of the required test area. Simultaneously, positioning lines are added to the spatial resolution test boards to facilitate positioning at 45° and -45° tilt test angles, thus obtaining spatial resolution at different angles. Furthermore, in terms of testing method, tests are performed separately at the center and four corners of the required test area for the photovoltaic photoluminescence defect detector, with each test position tested at a different angle. This allows for the measurement of the spatial resolution of the photovoltaic photoluminescence defect detector at different positions and angles. Ultimately, this achieves the evaluation of the spatial resolution of the photovoltaic photoluminescence defect detector imaging system, filling the gap in the prior art where precise evaluation of the specific location of the photovoltaic photoluminescence defect detector is impossible.

[0028] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0029] Please see Figure 6 As shown, this embodiment provides a spatial resolution test board for a photovoltaic photoluminescence defect detector, comprising a series of test boards, each of which corresponds to a different spatial resolution;

[0030] Each test plate is made of an opaque material and is a square of (20-50)mm × (20-50)mm with a thickness of less than 0.1mm. This thickness ensures both opacity and ease of operation.

[0031] Each of the test boards is provided with a spatial resolution mark, a rhombus positioning frame and n hollow rectangles (n≥2); the spatial resolution mark is located at one corner of the square; the rhombus positioning frame is inscribed in the midpoint of each side of the square; each hollow rectangle has the same length and width, and the distance between two adjacent rectangles is equal to the width of the rectangle;

[0032] The width and spacing of each of the hollow rectangles are determined by the spatial resolution of the test board, and the two satisfy the relationship Rs = 1 / 2d, where Rs is the spatial resolution (also the value marked on the spatial resolution) and d is the rectangle spacing and width.

[0033] Each test board is marked with a spatial resolution label, such as "0.71 lp / mm", to indicate the spatial resolution of that test card. The unit of spatial resolution is lp / mm (line pairs / millimeter), and the value on the front of different test boards is different. In this embodiment, among the series of test boards, the minimum spatial resolution is 0.25 lp / mm, and the spatial resolution of each subsequent test board is 10 times that of the previous test board's line pairs. 0.05 Times, and so on.

[0034] The diamond-shaped positioning frame is used because this device needs to measure the spatial resolution at four different test angles: horizontal, vertical, 45° tilt, and -45° tilt. Figure 6 The position shown is the vertical test angle. Rotating it 90° gives the horizontal test angle. Rotating it 45° clockwise gives the 45° tilt test angle. Rotating it -45° clockwise gives the -45° tilt test angle. The diamond positioning frame is used for positioning when rotating to the 45° and -45° tilt test angles. Positioning is completed when any line of the diamond positioning frame is rotated to the horizontal or vertical position.

[0035] With n hollowed-out rectangles, when light passes through them, a line pair image is formed on the screen of the photovoltaic photoluminescence defect detector, and the spatial resolution of the device can be determined based on the image.

[0036] Please see Figures 6 to 8 As shown, the spatial resolution testing method includes the following steps:

[0037] S1. Determine the test location as the center and four corners of the required test area for the photovoltaic photoluminescence defect detector;

[0038] S2. Place the spatial resolution test board with the minimum spatial resolution in different test positions in sequence; set the spatial resolution test board as the first test angle, place a solar cell or silicon wafer under the spatial resolution test board, and use the image spatial resolution test method to determine the spatial resolution corresponding to the test position at the first test angle.

[0039] S3. Rotate the spatial resolution test board to the second test angle and place it in different test positions in sequence. Place a solar cell or silicon wafer under the spatial resolution test board and use the image spatial resolution test method to determine the spatial resolution corresponding to the test position at the second test angle.

[0040] S4. Rotate the spatial resolution test board to the third test angle and place it in different test positions in sequence. Place a solar cell or silicon wafer under the spatial resolution test board and use the image spatial resolution test method to determine the spatial resolution corresponding to the test position at the third test angle.

[0041] S5. Rotate the spatial resolution test board to the fourth test angle and place it in different test positions in sequence. Place solar cells or silicon wafers under the spatial resolution test board and use the image spatial resolution test method to determine the spatial resolution corresponding to each test position at the fourth test angle.

[0042] S6. After obtaining the spatial resolution at different tilt angles at all positions, the lowest spatial resolution value among all test positions at the same test angle is the spatial resolution of the photovoltaic photoluminescence defect detector under test at that test angle.

[0043] The image spatial resolution test method determines the spatial resolution of a test position at the corresponding test angle as follows: First, use a spatial resolution test board with the lowest spatial resolution. Take an image with a photovoltaic photoluminescence defect detector. The image is a striped image with alternating bright and dark lines. By visual inspection, if n-1 black lines can be counted (n is the number of hollow rectangles on the spatial resolution test board), then replace it with the next spatial resolution test board. Continue until n-1 black lines cannot be counted on the image. The spatial resolution corresponding to the previous spatial resolution test board is the spatial resolution of each test position at the corresponding test angle.

[0044] The first test angle is a vertical test angle, which is the angle at which the long side of the spatial resolution test board rectangle is perpendicular to the horizontal line in the captured image. The second test angle is a horizontal test angle, which is the test angle corresponding to a 90° rotation of the vertical test angle. The third test angle is a 45° tilt, which is the test angle corresponding to a 45° clockwise rotation of the vertical test angle. The fourth test angle is a -45° tilt, which is the test angle corresponding to a -45° clockwise rotation of the vertical test angle.

[0045] In steps S4 and S5, when the spatial resolution test board is rotated to the third and fourth test angles, positioning is performed by the rhombus positioning frame in the spatial resolution test board. Positioning is completed when any line of the rhombus positioning frame is rotated to horizontal or vertical.

[0046] In steps S2, S3, S4, and S5, when the spatial resolution test board is placed sequentially at different test positions, it is necessary to ensure that the n hollow rectangles fall completely within the detection range of the photovoltaic photoluminescence defect detector, and also to ensure that the n hollow rectangles fall completely on the solar cell or silicon wafer.

[0047] The advantages of this invention are as follows: By setting up a series of spatial resolution test boards, each corresponding to a different spatial resolution, the size of the spatial resolution test boards is reduced, facilitating testing at different test positions such as the center and four corners of the required test area. Simultaneously, positioning lines are added to the spatial resolution test boards to facilitate positioning at 45° and -45° test angles, obtaining spatial resolution at different angles. Furthermore, in terms of testing method, tests are performed separately at the center and four corners of the required test area for the photovoltaic photoluminescence defect detector, with each test position tested at a different angle. This allows for the measurement of the spatial resolution of the photovoltaic photoluminescence defect detector at different positions and angles. Ultimately, this enables the evaluation of the spatial resolution of the photovoltaic photoluminescence defect detector imaging system, filling the gap in existing technologies that cannot accurately evaluate the specific location of the photovoltaic photoluminescence defect detector.

[0048] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for testing the spatial resolution of a photovoltaic photoluminescence defect detector, characterized in that: A series of spatial resolution test boards are used for testing, each corresponding to a different spatial resolution. Each test board is made of opaque material and is a square measuring 20-50mm × 20-50mm. Each test board has a spatial resolution mark, a rhombus positioning frame, and n hollow rectangles, where n ≥ 2. The spatial resolution mark is located at one corner of the square. The rhombus positioning frame is inscribed in the midpoint of each side of the square. The length and width of each hollow rectangle are equal, and the distance between two adjacent rectangles is equal to the width of the rectangle. The width and spacing of each hollow rectangle are determined by the spatial resolution corresponding to the test board, and the two satisfy the relationship Rs = 1 / 2d, where Rs is the spatial resolution and d is the rectangle spacing and width. The method for testing spatial resolution includes the following steps: S1. Determine the test location as the center and four corners of the required test area for the photovoltaic photoluminescence defect detector; S2. Place the spatial resolution test board with the minimum spatial resolution in different test positions in sequence; The spatial resolution test board is set as the first test angle, and a solar cell or silicon wafer is placed under the spatial resolution test board. The spatial resolution of each test position at the first test angle is determined by the image spatial resolution test method. S3. Rotate the spatial resolution test board to the second test angle and place it in different test positions in sequence. Place solar cells or silicon wafers under the spatial resolution test board and use the image spatial resolution test method to determine the spatial resolution corresponding to each test position at the second test angle. S4. Rotate the spatial resolution test board to the third test angle and place it in different test positions in sequence. Place solar cells or silicon wafers under the spatial resolution test board and use the image spatial resolution test method to determine the spatial resolution corresponding to each test position at the third test angle. S5. Rotate the spatial resolution test board to the fourth test angle and place it in different test positions in sequence. Place solar cells or silicon wafers under the spatial resolution test board and use the image spatial resolution test method to determine the spatial resolution corresponding to each test position at the fourth test angle. S6. After obtaining the spatial resolution at different tilt angles at all test positions, the lowest spatial resolution value among all test positions at the same test angle is the spatial resolution of the photovoltaic photoluminescence defect detector under test at that test angle. The image spatial resolution test method for determining the spatial resolution of a test location at the corresponding test angle is as follows: First, use a spatial resolution test board with the lowest spatial resolution and take an image with a photovoltaic photoluminescence defect detector. The image is a striped image with alternating bright and dark lines. By visual inspection, if n-1 black lines can be counted, then replace it with a spatial resolution test board with a higher spatial resolution. Continue until n-1 black lines cannot be counted in the image. The spatial resolution corresponding to the previous spatial resolution test board is the spatial resolution of the test location at the corresponding test angle.

2. The method for testing the spatial resolution of a photovoltaic photoluminescence defect detector as described in claim 1, characterized in that: The first test angle is a vertical test angle, the second test angle is a horizontal test angle, the third test angle is a 45° tilt, and the fourth test angle is a -45° tilt.

3. The method for testing the spatial resolution of a photovoltaic photoluminescence defect detector as described in claim 1, characterized in that: In steps S4 and S5, when the spatial resolution test board is rotated to the third or fourth test angle, it is positioned by the diamond-shaped positioning frame in the spatial resolution test board. Positioning is completed when any line of the diamond-shaped positioning frame is rotated to horizontal or vertical.

4. The method for testing the spatial resolution of a photovoltaic photoluminescence defect detector as described in claim 1, characterized in that: In steps S2, S3, S4, and S5, when the spatial resolution test board is placed sequentially at different test positions, it is necessary to ensure that the n hollow rectangles fall completely within the detection range of the photovoltaic photoluminescence defect detector, and also to ensure that the n hollow rectangles fall completely on the solar cell or silicon wafer.

5. The method for testing the spatial resolution of a photovoltaic photoluminescence defect detector as described in claim 1, characterized in that: In the series of test boards, the minimum spatial resolution is 0.25 lp / mm, and the spatial resolution of each subsequent test board is 10 times that of the previous test board. 0.05 Times, and so on.

Images