A method of testing a solar cell unit

Abstract

This invention provides a testing method for solar cell units, belonging to the field of photovoltaic technology. The testing method solves problems such as probe array shading and distorted efficiency calculations that occur when testing solar cells using traditional pressure testing methods, reducing the difficulty of cell testing. The method also avoids the problem of differences in actual power generation performance among cells in the same module due to welding and other processes after cell grading, ensuring that the electrical performance of each unit is more similar and effectively reducing the risk of module mismatch. Furthermore, the testing method enables the screening of solar cell unit structures and comprehensive monitoring of cell welding conditions, possessing significant application value.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic technology, specifically relating to a testing method for solar cell units. Background Technology

[0002] Silicon wafers undergo a series of processes such as texturing and diffusion to obtain finished cells. The inherent differences in silicon wafers and unstable factors in the manufacturing process may lead to greater differences in the electrical performance of cells in the same batch. Therefore, it is necessary to test the cells and classify them according to their actual conversion efficiency to meet the needs of subsequent module manufacturing and sales requirements.

[0003] Currently, commonly used solar cells mainly include MBB cells, gridless cells, special structure cells including shingled cells, and novel cells with grooved metal paste. However, traditional solar cell testing generally involves pressure testing of the main grid to collect the photocurrent. The probe array's shading prevents its number from increasing arbitrarily with the number of main grids. During MBB cell testing and sorting, the photocurrent is conducted from the fine grid to at least several main grids pressed by the probes, resulting in a longer photocurrent transmission path, increased line loss, and consequently, distorted electrical performance data. Gridless cells lack main grids and cannot be tested and sorted using conventional grid pressure testing methods. The probe array contacting the cell's fine grid may increase testing instability, leading to larger fluctuations in flyback distance (FF) and series resistance, making direct testing and sorting of cells difficult. Non-contact testing methods are limited by sensor accuracy and cannot currently achieve effective sorting and testing of gridless cells. Furthermore, traditional testing methods cannot guarantee the consistency of electrical performance among multiple small pieces of shingled cells after cutting, increasing the risk of module mismatch.

[0004] Furthermore, while traditional module manufacturing processes can reduce power loss caused by module mismatch due to mixed cell types, abnormalities such as slight exposed areas, incomplete soldering, varying degrees of shading, and flux crystallization during cell welding and other processes can exacerbate the differences in actual power generation performance after these processes, thereby further increasing the power loss caused by module mismatch.

[0005] Therefore, it is necessary to develop a testing method for solar cell units to address the shortcomings of existing technologies. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a testing method for solar cell units. This method solves problems such as probe array shading and distorted efficiency calculations that occur when testing solar cells using traditional pressure testing methods, thus reducing the difficulty of cell testing. Furthermore, this method avoids the problem of differences in actual power generation performance among cells in the same module due to welding and other processes after cell grading, ensuring that the electrical performance of each unit is more similar and effectively reducing the risk of module mismatch. The method also enables the screening of solar cell unit structures and comprehensive monitoring of cell welding conditions, demonstrating significant application value.

[0007] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0008] This invention provides a testing method for solar cell units, comprising: using the metal wires or busbars of the solar cell unit as power extraction points, collecting the photocurrent generated by the solar cell unit from the power extraction points, then conducting it through four wires to a data acquisition unit, and then calculating the various electrical performance data of the cell unit through a software control system.

[0009] Preferably, the steps of the testing method are as follows:

[0010] The solar cell unit is placed in the loading box of the upper unit. The upper robot transfers the solar cell unit to the conveyor mechanism, which then transports it to the test position of the test system unit. After the solar cell unit arrives at the designated test position, the upper and lower power collection units move from the standby point to the clamping point, forming good contact with the surface of the metal wires or busbars of the solar cell unit. Then, the photocurrent generated by the solar cell unit is collected from the power collection point and conducted through four wires to the data acquisition unit. The software control system then calculates the various electrical performance data of the cell unit.

[0011] After the test is completed, the upper and lower power supply units return to their standby positions. The solar cell units are then transported to the sorting unit by the transmission mechanism. The cell loading robot sorts the cell units into different boxes according to the gear settings of the control system, thus completing the test.

[0012] Preferably, the feeding box includes a solar cell testing box, a partitioned box, or other structural boxes.

[0013] Preferably, the loading robot transfers the battery cells to the conveying mechanism by vacuum adsorption or gripping.

[0014] Preferably, when there is a busbar on the front side of the solar cell unit, the upper power collection unit includes an upper power collection unit probe array and an upper power collection unit probe array bracket connected thereto.

[0015] The lower power extraction unit includes a conductive metal plate with multiple vacuum suction holes at the top. An insulating pad is provided at the top edge of the conductive metal plate, and a vacuum valve interface is provided on the side of the conductive metal plate. An insulating sealing layer is provided below the conductive metal plate, and a bottom support is provided below the insulating sealing layer.

[0016] Preferably, during testing, the upper power-taking unit probe array of the upper power-taking unit contacts the busbar of the solar cell unit, and the busbar is located above the insulating pad of the lower power-taking unit.

[0017] Preferably, when there are busbars on both sides of the solar cell unit, the upper power collection unit includes an upper power collection unit bracket, and upper power collection unit probe array and upper power collection unit insulating pressure block are respectively provided on both sides of the upper power collection unit bracket;

[0018] The lower power supply unit includes a lower power supply unit bracket, and a lower power supply unit probe array and a lower power supply unit insulating block are respectively provided on both sides of the lower power supply unit bracket. A lower power supply unit battery support platform is provided between the lower power supply unit probe array and the lower power supply unit insulating block.

[0019] The position of the probe array of the lower power-taking unit corresponds to the insulating pressure block of the upper power-taking unit, and the position of the probe array of the upper power-taking unit corresponds to the insulating pressure block of the lower power-taking unit.

[0020] Preferably, during solar cell unit testing, when the upper power-taking unit probe array and the lower power-taking unit insulating block are in the clamping position, the upper busbar is clamped in the middle, and when the lower power-taking unit probe array and the upper power-taking unit insulating block are in the clamping position, the lower busbar is clamped in the middle.

[0021] Preferably, the structure of the solar cell includes: a structure having a fine grid structure distributed throughout the cell area and a current collection structure perpendicular to the fine grid structure at the cell edge or outside.

[0022] Preferably, the fine grid structure is made of metal paste or metal wire.

[0023] Preferably, the current collecting structure is made of metal paste or metal wire.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] The testing method for solar cell units described in this invention is applicable to cells or cell units that have a fine grid structure distributed throughout the cell area on both the front and both sides, and that have a current collection perpendicular to the fine grid structure at the cell edge or outside. The cell type of the cell unit can be freely selected from various types of cells such as PERC, TopCon, HJT, and IBC. It also includes single / double-sided cells that utilize gridless, multi-grid, or shingled patterns, making it widely applicable.

[0026] The testing method described in this invention can test novel solar cell units formed by combining solar cells and metal wires. Unlike conventional battery testing, the power sampling point of this method is not on the silver grid on the surface of the cell, but on the metal wires connected to the cell. This method directly samples the electrical performance data from the current collection structure at the edge or outside of the cell, avoiding interference from the sampling device to the light intensity in standard light intensity testing, resulting in more accurate test results.

[0027] The testing method described in this invention directly tests solar cell units, enabling comprehensive testing and sorting of both cell characteristics and welding conditions, thus simplifying the module manufacturing process. This method also prevents significant differences in actual power generation performance caused by various process anomalies during welding and other processes, resulting in more similar electrical performance between different power generation units within the module and reducing the risk of module mismatch. Attached Figure Description

[0028] Figure 1 The diagram shows the structure of a solar cell unit. In the diagram, a~b are single-sided solar cell units with only one busbar; c~d are double-sided solar cell units with only one busbar.

[0029] Figure 2 The three views of the bottom-feed unit used to test a solar cell unit structure with only one busbar are shown in the figure. a is the top view, b is the front view, and c is the left view.

[0030] Figure 3 A schematic diagram of the top-feed unit used to test a solar cell unit structure with only one busbar.

[0031] Figure 4 This is a schematic diagram of a single-sided solar cell unit under test with only one busbar.

[0032] Figure 5 This is a bifacial solar cell unit with two busbars.

[0033] Figure 6 A schematic diagram of the upper and lower power extraction unit structure used for testing the upper and lower busbars.

[0034] Figure 7 This is a schematic diagram of the structure of a bifacial solar cell unit with two busbars during testing.

[0035] Figure label:

[0036] 1-Solar cell; 2-Front-side metal wire; 3-Back-side metal wire; 4-Busbar; 5-Vacuum suction hole; 6-Conductive metal plate; 7-Bottom bracket; 8-Vacuum valve interface; 9-Insulating sealing layer; 10-Insulating pad; 11-Upper power take-up unit probe array; 12-Upper power take-up unit probe array bracket; 13-Upper power take-up unit insulating block; 14-Upper power take-up unit bracket; 15-Lower power take-up unit insulating block; 16-Lower power take-up unit probe array; 17-Lower power take-up unit bracket; 18-Lower power take-up unit battery support platform. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto. Example 1:

[0038] This invention provides a method for testing solar cell units, comprising: placing the solar cell unit in the loading box of the upper unit; transferring the solar cell unit to a conveying mechanism via an upper robot; conveying the solar cell unit to a test position in the testing system unit via the conveying mechanism; after the solar cell unit is delivered to the designated test position, the upper and lower power-taking units move from the standby point to the clamping point, forming good contact with the surface of the metal wire or busbar 4 of the solar cell unit; the photocurrent generated by the solar cell unit is collected from the power-taking point and conducted through four wires to the data acquisition unit; the software control system then calculates the various electrical performance data of the cell unit; after the test is completed, the upper and lower power-taking units return to the standby point position; the solar cell unit is conveyed to the sorting unit by the conveying mechanism; and the loading robot sorts the cell units into different boxes according to the control system's setting, completing the test. In specific implementation, the loading box includes a solar cell testing box, a partitioned box, or other structural box; the upper robot transfers the cell unit to the conveying mechanism by vacuum adsorption or gripping.

[0039] like Figures 1-4 As shown, when the solar cell unit only has a busbar 4 on its front side, the upper power-taking unit includes an upper power-taking unit probe array 11 and an upper power-taking unit probe array bracket 12 connected to it; the lower power-taking unit includes a conductive metal plate 6, with multiple vacuum suction holes 5 at the top of the conductive metal plate 6, an insulating pad 10 at the top edge of the conductive metal plate 6, and a vacuum valve interface 8 on the side of the conductive metal plate 6; an insulating sealing layer 9 is provided below the conductive metal plate 6, and a bottom bracket 7 is provided below the insulating sealing layer 9. During testing, the upper power-taking unit probe array 11 of the upper power-taking unit contacts the busbar 4 of the solar cell unit, and the busbar 4 is located above the insulating pad 10 of the lower power-taking unit.

[0040] In practical implementation, since the upper power-taking unit probe array 11 is not used to test the main grid of the solar cell, but rather to contact the metal wire / busbar 4 of the solar cell unit, the requirements for the probe surface coating can be appropriately reduced, and the contact resistance only needs to meet the test requirements. Furthermore, since there is only one upper power-taking unit probe array 11, the shading is significantly improved compared to conventional cell testing. When the cell unit structure has the busbar arranged outside the cell area, the upper power-taking unit probe array 11 is also located outside the cell area, without obstructing the cell itself. Therefore, compared to traditional solar cell testing, which requires calculating the large shading area of ​​the probe array and then converting the shading to obtain the actual cell efficiency, this testing method has a smaller impact on the potential distortion of electrical performance data.

[0041] In practical implementation, the lower power-taking unit is designed as a conductive metal plate capable of vacuum suction. The metal material that directly contacts the back electrode / back metal wire of the battery cell requires good conductivity and low contact resistance (e.g., copper). A certain number of vacuum suction holes 5 are opened on the upper surface of the conductive metal plate 6 to attract the battery cell at the moment of testing, ensuring good contact between the battery cell's back electrode / back metal wire and the conductive metal plate 6. The size, number, and distribution of the vacuum suction holes 5 are determined by the flow rate required to attract different sizes of battery cells. The bottom support 7 is required to be insulated and assembled on the same support as the upper power-taking unit. Since the upper power-taking unit only presses on the battery area of ​​a single busbar 4, or even not at all, the vacuum suction must be achieved under conditions of low or no pressure to ensure sufficient contact between the back of the battery and the lower power-taking unit.

[0042] like Figures 5-7 As shown, when there are busbars 4 on both sides of the solar cell unit, the upper power-taking unit includes an upper power-taking unit bracket 14, and upper power-taking unit probe arrays 11 and upper power-taking unit insulating blocks 13 are respectively provided on both sides of the upper power-taking unit bracket 14; the lower power-taking unit includes a lower power-taking unit bracket 17, and lower power-taking unit probe arrays 16 and lower power-taking unit insulating blocks 15 are respectively provided on both sides of the lower power-taking unit bracket 17, and a lower power-taking unit battery support platform 18 is provided between the lower power-taking unit probe arrays 16 and the lower power-taking unit insulating blocks 15; the position of the lower power-taking unit probe arrays 16 corresponds to the position of the upper power-taking unit insulating blocks 13, and the position of the upper power-taking unit probe arrays 11 corresponds to the position of the lower power-taking unit insulating blocks 15. When the solar cell unit is being tested, the upper power-taking unit probe array 11 and the lower power-taking unit insulating block 13 clamp the upper busbar in the middle when they are in the clamping position, and the lower power-taking unit probe array 16 and the upper power-taking unit insulating block 15 clamp the lower busbar in the middle when they are in the clamping position.

[0043] In the specific implementation process, when the upper power-taking unit probe array 11 and the lower power-taking unit insulating block 15 are in the clamping position, they tightly clamp the upper busbar 4 in the middle, so that the charge carriers generated by the battery cell under standard light intensity are conducted to the upper power-taking unit through the busbar 4. When the lower power-taking unit probe array 16 and the upper power-taking unit insulating block 13 are in the clamping position, they tightly clamp the lower busbar 4 in the middle, so that the charge carriers generated by the battery cell under standard light intensity are conducted to the lower power-taking unit through the busbar 4.

[0044] In this embodiment, the structure of the solar cell includes: a fine grid structure distributed throughout the cell area, or a structure with current collection perpendicular to the fine grid structure at the cell edge or outside. The fine grid structure is composed of metal paste or metal wires; the current collection structure is also composed of metal paste or metal wires. Example 2:

[0045] Tests such as Figure 1 When the solar cell unit structures shown in a~d are in operation, after the aforementioned solar cell units reach the designated test position in the test system unit, the upper power-taking unit moves from the standby point to the clamping point, the lower power-taking unit activates vacuum, and the solar simulator begins operation. The upper and lower power-taking units collect the photocurrent from the cell unit by contacting the cell unit's metal wire or busbar 4, transmitting it to the data acquisition unit. The software control system then calculates the various electrical performance data of the cell unit. After obtaining the electrical performance parameters, the upper power-taking unit returns to the standby point, and the lower power-taking unit deactivates vacuum. The cell unit is then conveyed to the next unit by the conveying mechanism. The positions of the standby and clamping points, the degree of vacuum, etc., can be set according to actual needs. When the upper and lower power-taking units are at the clamping point, it is necessary to ensure good contact between the upper power-taking unit and the cell unit's busbar 4, and good contact between the lower power-taking unit and the cell unit's back electrode / back metal wire 3, so that the photocurrent can be transmitted from the cell unit to the power-taking unit. Example 3:

[0046] Tests such as Figure 5 When the solar cell unit structure shown is in place, the cell unit reaches the designated test position in the test system unit. The upper and lower power collection units move from the standby point to the clamping point. The positions of the standby point and the clamping point can be set with parameters as needed. However, when the upper and lower power collection units are in the clamping point position, it is necessary to ensure good contact between the upper and lower power collection units and the busbars 4 on the upper and lower sides of the solar cell unit, so that the photocurrent can be transmitted from the cell unit to the power collection unit for collection. After the upper and lower power collection units are in place, the solar simulator starts working. The upper and lower power collection units collect the photocurrent from the cell unit and transmit it to the data acquisition unit. The software control system calculates the various electrical performance data of the cell unit. After obtaining the electrical performance parameters, the upper and lower power collection units return to the standby point position, and the cell unit is conveyed to the next unit by the conveying mechanism.

[0047] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A testing method for a solar cell unit, characterized in that, The solar cell unit is a gridless, multi-grid, or shingled structure cell with a fine grid structure distributed throughout the cell area. The method includes: using a metal wire at the edge or outside of the solar cell unit as a power take-off point, or providing a bus bar (4) perpendicular to the fine grid structure at the edge or outside of the cell. Then, the bus bar (4) at the edge or outside of the solar cell unit is used as a power take-off point. The photocurrent generated by the solar cell unit is collected from the power take-off point, and then conducted to the data acquisition unit through four wires. The electrical performance data of the cell unit are then calculated by the software control system. The metal wire or bus bar (4) is arranged outside the cell area. The testing method is as follows: the solar cell unit is placed in the loading box of the upper unit, the upper robot transfers the solar cell unit to the conveying mechanism, and the conveying mechanism transmits the solar cell unit to the test position of the test system unit. After the solar cell unit is delivered to the designated test position, the upper power taking unit and the lower power taking unit move from the standby point to the clamping point and form good contact with the surface of the metal wire or busbar (4) of the solar cell unit. Then the photocurrent generated by the solar cell unit is collected from the power taking point and conducted to the data acquisition unit through four wires. The software control system then calculates the electrical performance data of the battery unit. After the test is completed, the upper power supply unit and the lower power supply unit return to the standby position. The solar cell unit is transported to the sorting unit by the transmission mechanism. The cell placement robot sorts the cell units into different boxes according to the gear setting of the control system to complete the test. When there is a busbar (4) on the front of the solar cell unit, the upper power supply unit includes an upper power supply unit probe array (11) and an upper power supply unit probe array bracket (12) connected thereto. The lower power extraction unit includes a conductive metal plate (6), with multiple vacuum suction holes (5) at the top of the conductive metal plate (6), an insulating pad (10) at the top edge of the conductive metal plate (6), and a vacuum valve interface (8) at the side of the conductive metal plate (6); an insulating sealing layer (9) is provided below the conductive metal plate (6), and a bottom support (7) is provided below the insulating sealing layer (9).

2. The testing method for solar cell units according to claim 1, characterized in that, The loading box includes a solar cell testing box, a partitioned box, or other structural boxes.

3. The testing method for solar cell units according to claim 1, characterized in that, The loading robot transfers the battery cells to the conveying mechanism by vacuum adsorption or gripping.

4. The testing method for solar cell units according to claim 1, characterized in that, During testing, the upper power-taking unit probe array (11) of the upper power-taking unit contacts the busbar (4) of the solar cell unit, which is located above the insulating pad (10) of the lower power-taking unit.

5. The testing method for a solar cell unit according to claim 1, characterized in that, When there is also a busbar (4) on the reverse side of the solar cell unit, the upper power collection unit includes an upper power collection unit bracket (14), and the upper power collection unit probe array (11) and the upper power collection unit insulating block (13) are respectively provided on both sides of the upper power collection unit bracket (14). The lower power supply unit includes a lower power supply unit bracket (17), and a lower power supply unit probe array (16) and a lower power supply unit insulating block (15) are respectively provided on both sides of the lower power supply unit bracket (17). A lower power supply unit battery carrying platform (18) is provided between the lower power supply unit probe array (16) and the lower power supply unit insulating block (15). The position of the lower power-taking unit probe array (16) corresponds to the position of the upper power-taking unit insulating block (13), and the position of the upper power-taking unit probe array (11) corresponds to the position of the lower power-taking unit insulating block (15).

6. The testing method for a solar cell unit according to claim 5, characterized in that, During solar cell unit testing, when the upper power-taking unit probe array (11) and the lower power-taking unit insulating block (15) are in the clamping position, the upper busbar (4) is clamped in the middle, and when the lower power-taking unit probe array (16) and the upper power-taking unit insulating block (13) are in the clamping position, the lower busbar (4) is clamped in the middle.

7. The testing method for a solar cell unit according to claim 1, characterized in that, The fine grid structure is made of metal paste or metal wires; the busbar is made of metal paste or metal wires.

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