EL detection structure for series welding production of photovoltaic cells

Abstract

The invention relates to the technical field of photovoltaic modules, and discloses an EL detection structure for series welding production of photovoltaic cells. A pressing head; the contact layer covers one side, close to the pressure head, of the electrode block, and the contact layer is made of a flexible conductive material; the welding strip is arranged on the contact layer, and the section of the welding strip is circular; the pressing head moves in the direction close to the electrode block, and the welding strip is pressed between the pressing head and the electrode block; the contact layer is extruded, the part, in contact with the welding strip, of the contact layer deforms, and the contact layer wraps part of the peripheral surface of the welding strip; according to the EL detection structure for series welding production of the photovoltaic cells, the contact layer made of the flexible conductive material is arranged between the electrode block and the pressure head, and when the pressure head presses the welding strip, the contact layer can deform and wrap a part of the peripheral surface of the welding strip, so that the contact area and the contact tightness of the welding strip and the electrode block are greatly increased, and the detection efficiency is improved. And the contact layer is simple and convenient to arrange, and can be widely applied to series welding production of various photovoltaic cells.

Description

Technical Field

[0001] The invention relates to the technical field of photovoltaic components, and in particular to an EL detection structure used in the production of photovoltaic cell series welding. Background Art

[0002] EL stands for Electro Luminescence, which can also be called electronic luminescence detection. EL detection is mainly used to detect internal defects of photovoltaic cell components. It applies reverse voltage to the photovoltaic cell components to excite the electrons inside them to produce fluorescence, thereby detecting defects inside the components.

[0003] HJT stands for Heterojunction Technology, which is a hybrid solar cell made of crystalline silicon as a substrate and amorphous silicon thin film. It has many advantages such as high efficiency, low light attenuation, high bifaciality and strong stability.

[0004] HJT cells are manufactured based on 120-micron-thick crystalline silicon wafers, and low-temperature ultra-thin film technology is used to make HJT cells. Multiple cells are then connected in series using a series welding process to form a cell string. The series welding process uses welding ribbons and main grids to weld multiple cells together. After series welding, the cell string needs to be subjected to EL testing to confirm the quality of the cell string.

[0005] In the prior art, when a battery string is subjected to EL detection, the bottom of the soldering ribbon contacts the copper electrode, and a soft pressure head above the soldering ribbon presses the soldering ribbon against the copper electrode. Both ends of the battery string contact the copper electrodes to provide voltage for EL detection.

[0006] However, in the above-mentioned EL detection process, on the one hand, the bottom of the soldering ribbon needs to be in close contact with the copper electrode to ensure that the current can pass smoothly. However, due to factors such as the material and shape of the soldering ribbon, the degree of contact between the soldering ribbon and the copper electrode often depends on the clamping setting of the pressure head. If the clamping force of the pressure head is insufficient or unevenly distributed, poor contact may occur between the soldering ribbon and the copper electrode. On the other hand, the soldering ribbon is easily affected by environmental factors during long-term storage or transportation, resulting in local oxidation on its surface. When the oxidized portion contacts the copper electrode, due to the presence of the oxide layer, an effective conductive connection cannot be formed, resulting in poor contact.

[0007] Furthermore, when the soldering ribbon is in poor contact with the copper electrode, the battery cells at both ends of the battery string cannot obtain sufficient voltage during the EL detection process, resulting in detection abnormalities. This abnormality is manifested as the appearance of black film in some parts of the battery cells, that is, this part of the battery cell appears as a black or dark area on the EL image, which cannot accurately reflect the actual situation inside it, resulting in a decrease in the accuracy of EL detection and an inability to accurately identify defects inside the battery cell.

[0008] To address the above defects, the contact performance between the soldering ribbon and the copper electrode is often improved by improving parameters such as the shape, material or pressing force distribution of the pressure head during production. However, this method requires a high R&D cost to design the pressure head, which is time-consuming and labor-intensive. Alternatively, during the production or storage of the soldering ribbon, the surface protection and treatment are strengthened to reduce the oxidation of the soldering ribbon. However, this method has limited treatment effects and cannot completely eliminate oxidation, and it will also affect the conductive properties of the soldering ribbon. Summary of the invention

[0009] In view of this, the present invention provides an EL detection structure for photovoltaic cell string welding production to solve the problem that the welding strip and the copper electrode are prone to poor contact during EL detection, while the existing production solutions are costly, time-consuming and labor-intensive, or will affect the conductive properties of the welding strip.

[0010] The present invention provides an EL detection structure for photovoltaic cell string welding production, comprising: an electrode block; a pressure head, located relatively above the electrode block; a contact layer, covering a side of the electrode block close to the pressure head, the contact layer being made of a flexible conductive material; a welding strip, placed at the contact layer, the cross-sectional shape of the welding strip being circular; wherein the pressure head is suitable for moving toward the electrode block so that the welding strip is pressed between the pressure head and the electrode block; wherein the contact layer is suitable for being squeezed by the pressure head, and a portion in contact with the welding strip is deformed, so that the contact layer is arranged to wrap around a portion of the outer circumference of the welding strip.

[0011] In an optional embodiment, it further includes a battery terminal connected to a side of the electrode block facing away from the pressure head.

[0012] In an optional embodiment, the pressure head includes a pressure rod, a pressure block and a pressure layer; the pressure rod is connected to the pressure block, the pressure layer is arranged on a side of the pressure block close to the electrode block, and the pressure layer is suitable for contacting the welding strip.

[0013] In an optional embodiment, the pressurizing layer is made of a flexible material.

[0014] In an optional embodiment, a plurality of the welding strips are compressed and arranged between the pressurizing layer and the contact layer.

[0015] In an optional implementation, the contact layer is a conductive tape.

[0016] In an optional embodiment, the pressurized layer is a silicone layer.

[0017] In an optional embodiment, at least two of the battery terminals are connected to the electrode block.

[0018] Beneficial effect: By setting a contact layer made of flexible conductive material between the electrode block and the pressure head, when the pressure head presses the welding strip, the contact layer can be deformed and wrap part of the outer circumference of the welding strip, thereby greatly increasing the contact area and contact tightness between the welding strip and the electrode block; compared with the existing point contact or line contact, the surface contact method can significantly improve the conductivity and contact stability between the welding strip and the electrode block.

[0019] Beneficial effects: Compared with the traditional method of improving contact performance by improving parameters such as the shape, material or clamping force distribution of the pressure head, there is no need for complex design and adjustment of the pressure head. Only a layer of conductive tape needs to be pasted on the electrode block, which greatly reduces the R&D cost and production cycle, and is easier to implement and promote.

[0020] Beneficial effect: The contact layer can wrap part of the outer circumference of the solder strip. Even if the solder strip is partially oxidized at the contact surface, it will not affect the contact performance between the solder strip as a whole and the electrode block. This solves the problem of poor contact caused by solder strip oxidation in the prior art, and there is no need for additional surface treatment or protection of the solder strip.

[0021] Beneficial effects: The contact layer is simple to set up and easy to operate, and can be quickly applied to the production line without large-scale transformation or adjustment of the production line, which helps to improve production efficiency and reduce downtime and labor costs in the production process.

[0022] Beneficial effect: The contact layer is made of flexible conductive material, and the setting of the contact layer will not affect the conductive performance of the welding strip itself, ensuring that the battery string can obtain sufficient voltage during the EL detection process, thereby accurately reflecting the real situation inside the battery cell.

[0023] Beneficial effects: The material and thickness of the contact layer can be selected according to actual production needs to adapt to different specifications and types of welding strips and electrode blocks. It has flexibility and scalability and can be widely used in various photovoltaic cell string welding production scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 It is a schematic diagram of the EL detection structure used in the photovoltaic cell string welding production of the present invention.

[0026] Description of reference numerals:

[0027] 1. Electrode block; 2. Press head; 21. Press rod; 22. Press block; 23. Pressurization layer; 3. Contact layer; 4. Welding strip; 5. Battery terminal. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0029] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] Combine the following Figure 1 , describing an embodiment of the present invention.

[0033] According to an embodiment of the present invention, there is provided an EL detection structure for the production of photovoltaic cell series welding, comprising: an electrode block 1; a pressure head 2, located relatively above the electrode block 1; a contact layer 3, covering a side of the electrode block 1 close to the pressure head 2, the contact layer 3 being made of a flexible conductive material; a welding strip 4, disposed at the contact layer 3, the cross-sectional shape of the welding strip 4 being circular; wherein the pressure head 2 is suitable for moving toward the direction close to the electrode block 1, so that the welding strip 4 is pressed tightly between the pressure head 2 and the electrode block 1; wherein the contact layer 3 is suitable for being squeezed by the pressure head 2, and the portion in contact with the welding strip 4 is deformed, so that the contact layer 3 is arranged to wrap a portion of the outer circumference of the welding strip 4.

[0034] The EL detection structure for photovoltaic cell string welding production also includes a battery terminal 5 connected to a side of the electrode block 1 away from the pressure head 2 .

[0035] The specific usage of the EL detection structure for the production of photovoltaic cell string welding includes, on the one hand, optimizing and improving the electrode block 1: the contact layer 3 can be a conductive tape, which has the advantage of being a common and easy-to-obtain material. Among them, a conductive tape with a certain thickness, good conductivity and soft material can be selected, and then the conductive tape is adhered to the surface of one side of the electrode block 1 close to the pressure head 2, or the conductive tape can be completely covered on the outside of the electrode block 1. The covering range can be selected according to actual production to ensure that the conductive tape covers the pressure-applied part of the pressure head 2 at the electrode block 1.

[0036] On the other hand, the battery string after welding is subjected to EL detection: the welding strip 4 is placed between the pressure head 2 and the electrode block 1, the cross-sectional shape of the welding strip 4 is circular, the circumferential surface below the welding strip 4 is in contact with the contact layer 3, and the ends of the battery string, i.e., the battery terminals 5, are connected to the electrode block 1; the pressure head 2 starts to press down to press the welding strip 4 tightly against the electrode block 1 for EL detection; wherein, the pressure head 2 presses the welding strip 4 so that the welding strip 4 presses the contact layer 3, and the contact layer 3 is a soft and flexible material, so that the layer body at the contact part between the contact layer 3 and the pressure head 2 is deformed, and the partial circumferential surface below the welding strip 4 is in contact with the contact layer 3, and the contact layer 3 wraps the partial circumferential surface, and the contact type between the welding strip 4 and the contact layer 3 is surface contact, which is compared with the existing Some methods directly extrude the welding strip 4 to make it contact with the electrode block 1. The provision of the contact layer 3 greatly increases the contact amount between the welding strip 4 and the electrode block 1, thereby achieving the purpose of improving the contact performance between the welding strip 4 and the electrode block 1. At the same time, the material of the contact layer 3 is easy to obtain and the operation is simple. It can effectively replace the improved method of designing the pressure head 2 in the existing production, and has an excellent effect on promoting the contact performance of the welding strip 4. Since the contact layer 3 wraps the partial circumference below the welding strip 4, when the welding strip 4 is locally oxidized at the contact surface, since the contact part between the welding strip 4 and the contact layer 3 is a complete arc surface, it does not affect the contact performance of the welding strip 4 as a whole with the electrode block 1, replaces the existing method of surface treatment of the welding strip 4 in production, and does not affect the conductive performance of the welding strip 4 itself.

[0037] Optionally, the electrode block 1 is a copper electrode.

[0038] The EL detection structure provided in this embodiment is characterized in that a contact layer 3 made of a flexible conductive material is arranged between the electrode block 1 and the pressure head 2. When the pressure head 2 presses the soldering strip 4, the contact layer 3 can be deformed and wrap a part of the outer circumference of the soldering strip 4, thereby greatly increasing the contact area and contact tightness between the soldering strip 4 and the electrode block 1. Compared with the existing point contact or line contact, the surface contact method can significantly improve the conductive performance and contact stability between the soldering strip 4 and the electrode block 1.

[0039] Compared with the traditional method of improving contact performance by improving parameters such as the shape, material or pressing force distribution of the pressure head 2, the EL detection structure provided in this embodiment does not require complicated design and adjustment of the pressure head 2. It only needs to stick a layer of conductive tape on the electrode block 1, which greatly reduces the R&D cost and production cycle and is easier to implement and promote.

[0040] In the EL detection structure provided in this embodiment, the contact layer 3 can wrap part of the outer peripheral surface of the soldering strip 4. Even if the soldering strip 4 is locally oxidized at the contact surface, it will not affect the contact performance between the soldering strip 4 and the electrode block 1 as a whole, thereby solving the problem of poor contact caused by oxidation of the soldering strip 4 in the prior art, and there is no need for additional surface treatment or protection of the soldering strip 4.

[0041] The EL detection structure provided in this embodiment has a simple and easy-to-operate contact layer 3, and can be quickly applied to a production line without large-scale transformation or adjustment of the production line, which helps to improve production efficiency and reduce downtime and labor costs in the production process.

[0042] In the EL detection structure provided in this embodiment, the contact layer 3 is made of a flexible conductive material. The setting of the contact layer 3 will not affect the conductive performance of the welding strip 4 itself, ensuring that the battery string can obtain sufficient voltage during the EL detection process, thereby accurately reflecting the actual situation inside the battery cell.

[0043] The EL detection structure provided in this embodiment has a contact layer 3 whose material and thickness can be selected according to actual production requirements to adapt to welding strips 4 and electrode blocks 1 of different specifications and types. It has flexibility and scalability and can be widely used in various photovoltaic cell string welding production scenarios.

[0044] In some embodiments, in combination Figure 1 As shown, the pressure head 2 includes a pressure rod 21, a pressure block 22 and a pressure layer 23; the pressure rod 21 is connected to the pressure block 22, and is used to transmit a clamping force to the pressure block 22. The pressure layer 23 is arranged on a side of the pressure block 22 close to the electrode block 1, and the pressure layer 23 is suitable for contacting the welding strip 4. The pressure layer 23 is made of a soft and flexible material, specifically silicone or rubber, to avoid damaging the surface of the welding strip 4 when pressing the welding strip 4.

[0045] In some embodiments, in combination Figure 1 As shown, the plurality of soldering strips 4 are compressed and arranged between the pressurizing layer 23 and the contact layer 3, and the contact layer 3 is deformed at the contact positions with the plurality of soldering strips 4 to respectively wrap the plurality of soldering strips 4.

[0046] In some embodiments, in combination Figure 1 As shown, at least two of the battery terminals 5 are connected to the electrode block 1. In this embodiment, the connecting ends at the left and right ends of the battery string, namely the battery terminals 5, are connected to the battery block.

[0047] Obviously, the above embodiments are only examples for clear explanation, and are not intended to limit the implementation methods. Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the present invention.

Claims

1. An EL detection structure for photovoltaic cell string welding production, characterized in that: include: Electrode block (1); A pressure head (2) located relatively above the electrode block (1); A contact layer (3) covering a side of the electrode block (1) close to the pressure head (2), wherein the contact layer (3) is made of a flexible conductive material; A welding strip (4) is placed on the contact layer (3), and the cross-sectional shape of the welding strip (4) is circular; The pressing head (2) is suitable for moving in a direction close to the electrode block (1) so that the welding strip (4) is pressed tightly between the pressing head (2) and the electrode block (1); The contact layer (3) is adapted to be squeezed by the pressure head (2), and a portion in contact with the welding strip (4) is deformed, so that the contact layer (3) wraps around a portion of the outer peripheral surface of the welding strip (4).

2. The EL detection structure for photovoltaic cell string welding production according to claim 1, characterized in that: It also includes a battery terminal (5) connected to a side of the electrode block (1) facing away from the pressure head (2).

3. The EL detection structure for photovoltaic cell string welding production according to claim 2, characterized in that: The pressure head (2) comprises a pressure rod (21), a pressure block (22) and a pressure layer (23); The pressure rod (21) is connected to the pressure block (22), the pressure layer (23) is arranged on a side of the pressure block (22) close to the electrode block (1), and the pressure layer (23) is suitable for contacting the welding strip (4).

4. The EL detection structure for photovoltaic cell string welding production according to claim 3, characterized in that: The pressurizing layer (23) is made of flexible material.

5. The EL detection structure for photovoltaic cell string welding production according to claim 4, characterized in that: A plurality of welding strips (4) are compressed and arranged between the pressurizing layer (23) and the contact layer (3).

6. The EL detection structure for photovoltaic cell string welding production according to claim 5, characterized in that: The contact layer (3) is a conductive tape.

7. The EL detection structure for photovoltaic cell string welding production according to claim 6, characterized in that: The pressurizing layer (23) is a silica gel layer.

8. The EL detection structure for photovoltaic cell string welding production according to claim 7, characterized in that: At least two of the battery terminals (5) are connected to the electrode block (1).

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