CN118039521B - Device and method for testing insulation property of thin grid of battery piece and preparation method of back contact assembly - Google Patents

Abstract

The present application discloses a cell fine grid insulation test device, method and back contact assembly preparation method, belonging to the technical field of insulation performance testing. The present application designs a test board suitable for back contact cell fine grid insulation performance testing, by pressing the test board down onto the back contact cell after printing the insulation glue, energizing the test board and taking the EL image of a single cell, quickly detecting the fine grid insulation performance of the cell to be tested; in the preparation process of the back contact assembly, after the cell is printed with the insulation glue and before the string welding step, a separate fine grid insulation test is added, and the fine grid insulation performance of the cell to be tested is quickly detected by combining the insulation test board with the EL test, and the position of the grid line with insufficient insulation performance can be located for subsequent repair, thereby ensuring the production efficiency and production yield in the assembly manufacturing process.

Description

A cell fine grid insulation test device, method and back contact assembly preparation method

Technical Field

The present application relates to the technical field of insulation performance testing, and more specifically, to a device and method for testing the insulation performance of a cell fine grid and a method for preparing a back contact assembly.

Background technique

In solar energy applications, photovoltaic power generation is an important application mode, which has gradually been widely used due to its advantages such as no noise, maintenance-free and emission-free. At present, thanks to the abundant reserves of silicon materials in the earth's crust, relatively mature photovoltaic power generation technology and low cost, crystalline silicon solar cells dominate the field of photovoltaic power generation. Compared with other types of commercial cells, crystalline silicon solar cells have higher conversion efficiency. At present, high-conversion-efficiency back-contact cells and back-contact modules are the main development trend of crystalline silicon photovoltaic modules.

The structural feature of the back-contact battery is that there is no grid line on the front side, and the positive and negative grid lines are printed on the back side at the same time, and the positive and negative grid lines are arranged in a forked finger shape. Since the battery cell will be short-circuited when the positive and negative grid lines are in contact through the conductor, this forked finger arrangement will require that the probes be set on the same side of the battery cell when testing the back-contact battery, and the test probes on adjacent main grids cannot be electrically connected to each other, which brings difficulties to the structural design of the back-contact battery cell test board.

On the other hand, during the production of back-contact modules, the welding strips need to be welded to the positive and negative main grids of the cells respectively, and connected to other cells to form a battery string. Since the positive and negative grids are in a forked shape, the welding strips are very likely to overlap with the adjacent thin grids with opposite electrical properties when welded to the main grid, thus causing a local short circuit and affecting the power output of the module.

To solve the problem of local short circuit, some technicians proposed to print insulating glue near the main grid before string welding, so as to isolate the adjacent fine grids from the welding strips. However, in the actual production process, due to the limited yield, the insulating glue is sometimes not printed completely, which may lead to the possibility of short circuit between the fine grid and the welding strip.

The current production method is to directly weld the cells with printed insulating glue into a cell string, and then perform EL testing on the cell string, using the electroluminescent recombination of minority carriers to collect the fluorescence emitted by the photovoltaic module when biased, take the EL image of the cell string, and detect the welding effect of the cell and the printing effect of the insulating glue at the same time, so as to reversely infer whether there is a problem with the printing of the insulating glue. This judgment method improves the efficiency of performance testing of the cell string, but it is difficult to locate and improve the process problem points, and the production efficiency and production yield of the cell string are not high.

After searching, the patent application number is 202310669067.3, the application publication date is August 25, 2023, and the patent name is: A method for testing the performance of an IBC solar cell. The application covers a high-transmittance glass plate on the IBC battery to be tested, and the grid line printing side of the IBC battery to be tested is set downward; a cross-arranged flexible copper foil is laid on the bottom plate to abut against the main grid of the IBC battery to be tested; the busbars are welded at both ends of the flexible copper foil and the positive and negative electrodes are led out; the high-transmittance glass plate is fixedly connected to the bottom plate so that the positive and negative electrodes are connected to an external battery tester to complete the battery electrical performance test. This application realizes that the IBC battery uses a full-surface flexible crimping method to simulate the connection status in the component to test the battery efficiency. It can detect the overall performance of a single-chip battery, and can also detect the problem of poor printing of its insulating glue in advance during the test, eliminating the risk of subsequent repairs. However, this application is intended to test the electrical performance parameters of the IBC battery, and can only be reversed from the tested battery electrical parameters to indirectly determine whether the battery cell has poor printing. This method of judging whether a cell is poorly printed has two defects. First, the electrical performance parameters of a cell are determined by multiple factors. It is impossible to judge whether the defect is caused by poor printing based on the electrical performance parameters alone. It is also possible that the cell is short-circuited due to electrode burn-through, contamination, etc. In these cases, the electrical performance parameters are consistent with poor printing. Second, even if it is determined that the cause of the electrical performance abnormality is poor cell printing, it is impossible to determine the location where the short circuit occurs in the cell. In this way, it is impossible to accurately locate the location of the poor printing, which is not conducive to the repair of the cell.

Summary of the invention

1. Technical problems to be solved

In response to the problems existing in the above-mentioned prior art, the present application provides a device and method for testing the fine grid insulation of a battery cell and a method for preparing a back-contact component. The present application designs a test board suitable for testing the fine grid insulation performance of a back-contact battery cell. Combined with the EL test, the fine grid insulation performance of the battery cell to be tested can be quickly detected after the battery cell is printed with insulating glue and before the string welding step. The position of the grid line with insufficient insulation performance can be located for subsequent repair, thereby ensuring the production efficiency and production yield in the component manufacturing process.

2. Technical solution

The content of this application is used to introduce the concepts in a brief form, and these concepts will be described in detail in the detailed implementation section below. The content of this application is not intended to identify the key features or essential features of the technical solution claimed for protection, nor is it intended to limit the scope of the technical solution claimed for protection. The technical solution provided by this application is:

As a first aspect of the present application, the present application provides a battery cell fine grid insulation test device, including a test board, wherein the test board includes a positive test probe, a negative test probe, a positive conductive plate, a negative conductive plate and an insulating plate, the test probe and the conductive plate are both arranged on the insulating plate, the positive test probe is electrically connected to the positive conductive plate, and the negative test probe is electrically connected to the negative conductive plate; the positive test probe and the negative test probe, and the positive conductive plate and the negative conductive plate are insulated from each other.

Furthermore, the positive conductive plate and the negative conductive plate of the test board are electrically connected to the EL test probes respectively; and an infrared image of the battery cell after power-on is captured by an infrared camera.

Furthermore, the number and relative positions of the positive electrode test probes and the negative electrode test probes are consistent with the number and positions of welding strips to be welded to the corresponding battery cell to be tested.

Furthermore, the width of the positive electrode test probe and the negative electrode test probe is greater than the width of the main grid on the battery cell.

Furthermore, the test probe and the conductive plate are both made of conductive materials, including metallic conductive materials and non-metallic conductive materials.

Furthermore, the metal conductive material is one of gold, silver, copper, and aluminum-copper alloy; and the non-metal conductive material is graphite.

Furthermore, the test probe and the conductive plate are connected to the insulating plate by adhesive.

As the second aspect of the present application, the present application provides a method for testing the insulation of fine grids of a battery cell, wherein a test board is pressed onto a battery cell on which insulating glue is printed, the center of the test probe of the test board is aligned with the main grid of the battery cell, and the test probe simultaneously presses the main grid and the fine grid part on which insulating glue is printed around the main grid; then, the EL test probe is electrically connected to the positive conductive plate and the negative conductive plate respectively, and an infrared image of the battery cell is taken after power is turned on. If a large area of the fine grid part between the two main grids in the image is black, it is determined that the insulating glue printing in this area is poor.

As the third aspect of the present application, the present application provides a method for preparing a back contact assembly. After printing the insulating glue on the battery cell and before the string welding step, the fine grid insulation performance of the battery cell is detected by using the device and the test method. After confirming that there is no printing defect, the back contact assembly is further prepared.

Furthermore, the preparation method of the present application specifically comprises the following steps:

Step 1: Place the battery cell into the screen printer and print the insulating glue at the preset printing position;

Step 2: Use the insulation testing device and method to test the back contact cell after printing the insulation glue to determine whether there is a bad printing; if the image is bright and there is no obvious defect, the cell is used for the next step of string welding;

Step 3: Weld the solder strips on the battery cells to interconnect the battery cells to obtain battery strings, and use EL to detect the welding effect; remove the battery strings with poor welding and rework them, and use the remaining battery strings for the next step;

Step 4: Lay EVA film and welded battery strings on the glass in sequence, weld the battery strings to the busbars to interconnect the battery strings, and then lay EVA film and back sheet in sequence to form a laminate;

Step 5: Test the EL image of the laminate. If the image is bright and has no obvious defects, it means that the installation is correct.

Step 6: Use edge tape to seal the edges of the laminated piece, and then send it to the laminator for lamination;

Step 7: Take out the laminated component after lamination, tear off the edge tape, install the middle bus bar on the junction box, and then use silicone glue to install the photovoltaic frame around the laminated component. Wait for the insulating glue in the frame to cure to obtain the finished back-contact photovoltaic module.

3. Beneficial effects

Compared with the existing known technologies, the technical solution provided by this application has the following significant effects:

(1) The present application designs a test board suitable for testing the fine grid insulation performance of back-contacted solar cells. By pressing the test board down onto the back-contacted solar cell printed with insulating glue, the test board is powered on and an EL image of a single solar cell is taken to quickly detect the fine grid insulation performance of the solar cell to be tested, and the position of the grid line with insufficient insulation performance can be located;

(2) This application adds a separate fine grid insulation test after printing the insulating glue on the battery cell and before the string soldering step. Through the insulation test board combined with the EL test, the fine grid insulation performance of the battery cell to be tested can be quickly detected, and the position of the grid line with insufficient insulation performance can be located for subsequent repair, thereby ensuring the production efficiency and production yield in the component manufacturing process.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings constituting a part of this application are used to provide a further understanding of this application, so that other features, purposes and advantages of this application become more obvious. The drawings and descriptions of the exemplary embodiments of this application are used to explain this application and do not constitute an improper limitation on this application.

In addition, throughout the drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and that the components and elements are not necessarily drawn to scale.

In the attached picture:

FIG1 is a process flow diagram of a back contact assembly according to an embodiment of the present application;

FIG2 is a schematic diagram of an exploded structure of a fine-grid insulation test board for a back contact assembly according to an embodiment of the present application;

FIG3 is a schematic diagram of the combined structure of a back contact assembly fine gate insulation test board according to an embodiment of the present application;

4 and 5 are schematic diagrams of a fine gate insulation test of a back contact assembly according to an embodiment of the present application.

Explanation of the symbols in the schematic diagram:

11. Positive electrode test probe; 12. Negative electrode test probe; 21. Positive electrode conductive plate; 22. Negative electrode conductive plate; 3. Insulating plate; 4. Battery cell; 41. Main grid.

Detailed ways

In order to further understand the content of the present application, the present application is described in detail with reference to the accompanying drawings and embodiments.

Embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms, and should not be construed as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided to provide a more thorough and complete understanding of the present application. It should be understood that the drawings and embodiments of the present application are only for exemplary purposes and are not intended to limit the scope of protection of the present application.

It should also be noted that, for ease of description, only the parts related to the invention are shown in the drawings. In the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other.

It should be noted that the modifications of "one" and "plurality" mentioned in the present application are illustrative rather than restrictive, and those skilled in the art should understand that unless otherwise clearly indicated in the context, it should be understood as "one or more".

The present application will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

The back contact battery is a new type of battery technology. In the current production process, R&D personnel usually focus on taking various means to test the IV characteristics of the battery cells, and use the IV characteristics to indirectly reflect the insulation quality. And because of the unique interdigitated grid line structure of the back contact battery, if you want to test its fine grid insulation, each main grid on the battery cell needs to be covered with a test probe, and the probes on adjacent main grids are insulated from each other and cannot be electrically connected, which makes the specific implementation of the test more difficult. Therefore, the current technical solution is to directly weld the battery cells printed with insulating glue into a battery string, and then take the EL image of the battery string, and at the same time detect the welding effect of the battery cells and the printing effect of the insulating glue, so as to reversely infer whether there is a problem with the printing of the insulating glue. It can be said that using EL testing to observe the welding effect during the production process of back contact battery components, and indirectly observing and judging the fine grid insulation performance while testing the welding effect, has become a conventional method in the industry.

However, the inventor believes through analysis that this judgment method has two significant defects: First, the observed short circuit of the battery cell is not necessarily caused by poor printing of the insulating glue, but may also be caused by excessive deviation of the solder strip during the string welding process, poor soldering of the solder strip, etc. Further manual judgment may be required to determine whether the observed short circuit is caused by poor printing or poor string welding, which makes it difficult to locate and improve process problem points, resulting in reduced production efficiency. Second, even if it can be determined that the short circuit is caused by poor printing of the insulating glue, a single short-circuited battery cell has been interconnected with other normal battery cells to form a battery string, and the workload of rework is large or even impossible to rework, and the entire string can only be downgraded or abandoned, resulting in a decrease in production yield.

Based on the above analysis, referring to Figures 2 and 3, an embodiment of the present application designs a test board used in the fine grid insulation test. The test board includes a positive test probe 11, a negative test probe 12, a positive conductive plate 21, a negative conductive plate 22 and an insulating plate 3. The test probe and the conductive plate are both connected to the insulating plate 3 by adhesive, and the positive test probe 11 is electrically connected to the positive conductive plate 21, and the negative test probe 12 is electrically connected to the negative conductive plate 22. There is no electrical connection between the positive and negative test probes and the positive and negative conductive plates. The material of the insulating plate 3 includes but is not limited to PET board, PC board, PVC board, and the test probe and the conductive plate are both conductive materials, including metals such as gold, silver, copper, and alloys such as aluminum-copper alloys, and also non-metallic conductive materials such as graphite. The number and relative position of the test probes are consistent with the number and position of the subsequent welding strips of the corresponding battery cell 4 to be tested, and are arranged in a staggered manner. The width of the test probe needs to be slightly wider than the width of the main grid 41, and its specific size can be adjusted according to actual test requirements. The size of the conductive plate should be suitable to meet the size of the external EL test probe.

The method for using the test board of the present application to test the fine grid insulation is as follows: during the test, the test board is pressed onto the battery cell 4 on which the insulating glue is printed, the center of the test probe of the test board is aligned with the main grid 41 of the battery cell, and the test probe is pressed onto the main grid 41 and the fine grid portion on which the insulating glue is printed around the main grid 41 at the same time. Then, the EL test probe is pressed onto the positive and negative conductive plates respectively, and an infrared image of the battery cell is taken after power is turned on. If a large area of the fine grid portion between the two main grids in the image is black, it is determined that the insulating glue printing in this area is poor.

Another specific embodiment of the present application is a test board for testing the fine grid insulation of a 166-10BB half-cell back-contact battery cell. The positive and negative test probes are made of copper, and the number is 5. The width of the test probe is consistent with the width of the battery cell pad point, which is 2.1mm. The length of the test probe is consistent with the main grid length, which is 90mm. The depth of the test probe is 5mm. The conductive plates connected to the test probes are also made of copper, which is 19mm along the length direction of the battery cell, 5mm wide, and 3mm thick. During the test, the side of the battery cell with the grid line is facing up, and the probe on the test board is pressed onto the main grid of the battery cell, as shown in Figures 4 and 5. Then, the probes of the external EL power supply are pressed onto the positive and negative conductive plates respectively. After power is turned on, the EL image of the battery cell can be captured.

The present application quickly detects the fine grid insulation performance of the cell to be tested by pressing the test board down onto the back contact cell after printing the insulating glue, energizing the test board and taking the EL image of a single cell, and can locate the position of the grid line with insufficient insulation performance for subsequent repair, thereby ensuring production efficiency in the component manufacturing process.

In conjunction with FIG. 1 , another specific embodiment of the present application provides a method for preparing a back contact assembly, the steps of which are:

Step 1: Place the battery cell into the screen printer and print the insulating glue at the preset printing position;

Step 2: Use the insulation testing device and method of the previous embodiment of the present application to test the back contact battery after printing the insulation glue to determine whether there is a bad printing; if the image is bright and there is no obvious defect, the battery cell is used for the next step of string welding;

Step 3: Use a stringer to weld the cells with printed insulating glue, weld the welding strips on the cells to interconnect the cells, thereby obtaining a cell string, and use EL to detect the welding effect; remove the cell strings with poor welding and rework them, and use the remaining cell strings for the next step;

Step 4: Lay EVA film and welded battery strings on the glass in sequence, weld the battery strings to the busbars to interconnect the battery strings, and then lay EVA film and back sheet in sequence to form a laminate;

Step 5: Test the EL image of the laminate. If the image is bright and has no obvious defects, it means that the installation is correct.

Step 6: Use edge tape to seal the edges of the laminated piece, and then send it to the laminator for lamination;

Step 7: Take out the laminated component after lamination, tear off the edge tape, install the middle bus bar on the junction box, and then use silicone glue to install the photovoltaic frame around the laminate. Wait for the insulating glue in the frame to cure to obtain the finished back-contact photovoltaic module.

The present application designs a test board suitable for testing the fine grid insulation performance of back-contact solar cells, and combines it with the EL test to add a separate fine grid insulation test after printing the insulating glue on the solar cells and before the string soldering step. This can quickly detect the fine grid insulation performance of the solar cells to be tested and locate the positions of the grid lines with insufficient insulation performance for subsequent repairs, thereby ensuring production efficiency and production yield in the component manufacturing process.

The above description is only some preferred embodiments of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present application is not limited to the technical solutions formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above invention concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the embodiments of the present application to form a technical solution.

Claims (9)

1. A battery cell fine grid insulation test device, characterized in that: it comprises a test board, the test board comprises a positive electrode test probe (11), a negative electrode test probe (12), a positive electrode conductive plate (21), a negative electrode conductive plate (22) and an insulating plate (3), the test probe and the conductive plate are both arranged on the insulating plate (3), the positive electrode test probe (11) is electrically connected to the positive electrode conductive plate (21), and the negative electrode test probe (12) is electrically connected to the negative electrode conductive plate (22); the positive electrode test probe (11) and the negative electrode test probe (12), and the positive electrode conductive plate (21) and the negative electrode conductive plate (22) are insulated from each other; The number and relative positions of the positive electrode test probes (11) and the negative electrode test probes (12) are consistent with the number and positions of the main grids (41) to be welded to the corresponding battery cell (4) to be tested. 2. A cell fine grid insulation test device according to claim 1, characterized in that: the positive conductive plate (21) and the negative conductive plate (22) of the test board are electrically connected to the EL test probe respectively; and an infrared camera is used to capture an infrared image of the cell (4) after power is turned on. 3. A cell thin grid insulation test device according to claim 2, characterized in that the width of the positive electrode test probe (11) and the negative electrode test probe (12) are greater than the width of the main grid (41) on the cell (4). 4. A cell fine grid insulation test device according to claim 3, characterized in that the test probe and the conductive plate are made of metallic conductive material or non-metallic conductive material. 5. A cell fine grid insulation test device according to claim 4, characterized in that: the metal conductive material is one of gold, silver, copper, and aluminum-copper alloy; the non-metallic conductive material is graphite. 6. A cell fine grid insulation test device according to claim 5, characterized in that: the test probe and the conductive plate are connected to the insulating plate (3) by adhesive. 7. A method for testing the insulation of fine grids of a battery cell using the device according to any one of claims 1 to 6, characterized in that: a test board is pressed onto a battery cell (4) on which insulating glue is printed, the center of the test probe of the test board is aligned with the main grid (41) of the battery cell, and the test probe simultaneously presses the main grid (41) and the fine grid portion on which insulating glue is printed around the main grid (41); then, the EL test probe is electrically connected to the positive conductive plate (21) and the negative conductive plate (22) respectively, and an infrared image of the battery cell (4) is taken after power is turned on. If a large area of the fine grid portion between the two main grids (41) in the image is black, it is determined that the insulating glue printing in this area is poor. 8. A method for preparing a back contact assembly, characterized in that: after printing the insulating glue on the battery cell and before the string welding step, the test method described in claim 7 is used to detect the fine grid insulation performance of the battery cell, and after confirming that there is no printing defect, the back contact assembly is further prepared. 9. A method for preparing a back contact assembly according to claim 8, characterized in that it comprises the following steps: Step 1: Place the battery cell into the screen printer and print the insulating glue at the preset printing position; Step 2: Use the insulation testing device and method to test the back contact cell after printing the insulation glue to determine whether there is a bad printing; if the image is bright and there is no obvious defect, the cell is used for the next step of string welding; Step 3: Weld the solder strips on the battery cells to interconnect the battery cells to obtain battery strings, and use EL to detect the welding effect; remove the battery strings with poor welding and rework them, and use the remaining battery strings for the next step; Step 4: Lay EVA film and welded battery strings on the glass in sequence, weld the battery strings to the busbars to interconnect the battery strings, and then lay EVA film and back sheet in sequence to form a laminate; Step 5: Test the EL image of the laminate. If the image is bright and has no obvious defects, it means that the installation is correct. Step 6: Use edge tape to seal the edges of the laminated piece, and then send it to the laminator for lamination; Step 7: Take out the laminated component after lamination, tear off the edge tape, install the middle bus bar on the junction box, and then use silicone glue to install the photovoltaic frame around the laminate. Wait for the insulating glue in the frame to cure to obtain the finished back-contact photovoltaic module.