Battery string and photovoltaic module

Abstract

The utility model relates to a cell string and a photovoltaic assembly, comprising a plurality of cell sheets and a solder strip connecting adjacent cell sheets in series, the solder strip has a bottom and two opposite side portions, the two opposite side portions of the solder strip and the surfaces of the cell sheets are fixed through adhesive glue, and the bottom of the solder strip is provided with a bottom surface. The bottom and the surface of the battery piece are attached in a surface contact mode or a line contact mode, and no adhesive is arranged between the bottom and the surface of the battery piece. According to the fixing mode between the welding strip and the battery piece of the battery string, the bonding glue is arranged between the two side parts of the welding strip and the battery piece, and the welding strip is fixed on the battery piece from the side surface, so that the problem of insufficient welding caused by the fact that the bonding glue enters the bottom of the welding strip can be avoided.

Description

Technical Field

[0001] This utility model relates to the field of photovoltaic module technology, and in particular to a battery string and a photovoltaic module containing the battery string. Background Technology

[0002] Conventional photovoltaic (PV) modules have numerous fine grid lines printed on their cells to collect the current generated when the cells are exposed to sunlight. They also have multiple main grid lines printed on the fine grid lines to collect the current from these main grid lines. Both the fine and main grid lines are obtained using silver paste printing. Therefore, silver paste accounts for a significant portion of the non-silicon costs in conventional PV modules. Given the current surge in silver prices, finer grid lines are more advantageous in reducing silver paste usage, thus lowering costs, while also reducing shading of the cells and improving power generation efficiency. This has led to the development of gridless solar cell technology.

[0003] Gridless solar cells are a design that eliminates the main grid lines from conventional solar cells, using only fine grid lines. Current is conducted through solder ribbons in the module stage. Depending on the interconnection method between the solder ribbons and the solar cells, gridless solar cells can be categorized into four main types of string bonding: SmartWire, film coating, welding + dispensing, and dispensing.

[0004] In this process, adhesive dispensing involves applying adhesive dots to the solar cell, then pre-fixing the solder ribbon to the cell using these dots, and finally alloying the solder ribbon and cell through lamination. It's clear that dispensing simply uses adhesive to connect the solder ribbon and cell. While this method promises to reduce steps and costs, existing dispensing technologies commonly suffer from problems such as insulating adhesive seeping into the bottom of the solder ribbon, leading to poor adhesion between the ribbon and cell. Furthermore, during module lamination, the high fluidity of the adhesive film can cause it to seep into the space between the solder ribbon and the cell, ultimately resulting in issues like poor solder joints and black spots on the electroluminescent substrate (EL). Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a battery string that can prevent the problem of incomplete soldering caused by adhesive entering the bottom of the solder strip.

[0006] The second aspect of this invention is to provide a photovoltaic module that can improve the problem of EL blackening caused by the large flow of the adhesive film during lamination, which leads to the adhesive film penetrating between the solar cell and the solder ribbon.

[0007] To solve the above technical problems, the present invention adopts the following technical solution:

[0008] A battery string includes a plurality of battery cells and a solder strip connecting adjacent battery cells in series. The solder strip has a bottom and opposite side portions. The opposite side portions of the solder strip are fixed to the surface of the battery cells by adhesive. The bottom is in surface contact or line contact with the surface of the battery cells. When the bottom is in line contact with the surface of the battery cells, the distance between the adhesive strips on opposite sides of the solder strip is 0.6DD, where D refers to the width of the solder strip. When the bottom is in surface contact with the surface of the battery cells, the side portions are respectively in close contact with the adhesive strips on their corresponding sides. No adhesive strip is provided between the bottom and the surface of the battery cells.

[0009] By adopting the above technical solution, the problem of EL blackening caused by the large flow of the encapsulant film during photovoltaic module lamination and its penetration into the space between the cell and the solder ribbon can be improved.

[0010] In this invention, the “width” of the solder strip refers to the lateral dimension of the solder strip in the forward projection on the battery cell, and the lateral dimension is perpendicular to the length direction of the solder strip.

[0011] In this invention, the distance between the adhesives on opposite sides of the solder strip is 0.6DD, which means that the distance between the adhesives on opposite sides of the solder strip is greater than or equal to 0.6D and less than or equal to D.

[0012] In some embodiments, the cross-sectional shape of the welding strip is circular, square, or irregular.

[0013] The term "irregular shape" refers to a cross-sectional shape of the welding strip other than a circle or a square. Other shapes include regular or irregular shapes, such as oval, triangle, etc.

[0014] In some embodiments, the adhesive is continuously disposed along the length of the solder strip, which can further improve the EL blackening problem of photovoltaic modules.

[0015] In some embodiments, the adhesive is an insulating adhesive.

[0016] In some specific embodiments, the insulating adhesive includes, but is not limited to, hot melt adhesive, thermosetting adhesive, or UV-curing adhesive, all of which are commercially available.

[0017] In some embodiments, the solder strip is a low-temperature solder strip.

[0018] The welding temperature of room temperature soldering strips is generally around 260℃, while the welding temperature of low temperature soldering strips is much lower, only around 150℃ is needed. Low temperature soldering strips have a low welding temperature, save energy, and produce stable and reliable welds.

[0019] In some embodiments, the solar cell is a gridless solar cell.

[0020] In some embodiments, the solar cell is a tunnel oxide passivated contact solar cell, a heterojunction solar cell, or a back contact solar cell.

[0021] The second technical solution adopted by this utility model is: a photovoltaic module, comprising a film, a battery string and a backsheet stacked in sequence, wherein the battery string is the battery string described above.

[0022] In some embodiments, the back sheet includes, but is not limited to, a glass back sheet or a polymer film back sheet.

[0023] Due to the application of the above technical solution, this utility model has the following advantages compared with the prior art:

[0024] The present invention uses an adhesive to fix the welding strip and the battery cell in the battery string by placing adhesive between the two sides of the welding strip and the battery cell, thereby fixing the welding strip to the battery cell from the side. This can avoid the problem of poor welding caused by the adhesive entering the bottom of the welding strip. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings.

[0026] Figure 1 This is a front view of the battery string structure of Embodiment 1 of this utility model (without solder strips laid);

[0027] Figure 2 for Figure 1 Enlarged view of point A;

[0028] Figure 3 This is a front view schematic diagram of the battery string structure in Example 1 (with solder strips laid);

[0029] Figure 4 for Figure 3 Enlarged view of point B in the middle;

[0030] Figure 5 This is a schematic diagram of the cross-sectional structure of the battery string in Example 1;

[0031] Figure 6 This is a schematic diagram of the cross-sectional structure of the solder strip in the battery string of Example 1;

[0032] Figure 7 This is a schematic diagram of the cross-sectional structure of the battery string in Example 2;

[0033] Figure 8This is a schematic diagram of the cross-sectional structure of the battery string in Example 3;

[0034] Figure 9 This is a schematic diagram of the cross-sectional structure of the solder strip in the battery string of Example 3;

[0035] Figure 10 This is a schematic diagram of the cross-sectional structure of the battery string in Example 4;

[0036] Figure 11 This is a schematic diagram of the cross-sectional structure of the solder strip in the battery string of Example 4;

[0037] Figure label:

[0038] 1. Battery cell; 2. Welding strip; 21. Bottom; 22. Side; 3. Adhesive. Detailed Implementation

[0039] To enable those skilled in the art to better understand the technical solutions in the embodiments of this utility model, the technical solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art should fall within the protection scope of this utility model.

[0040] Example 1

[0041] See Figures 1-5 The battery string in this embodiment includes a plurality of battery cells 1 and a solder strip 2 connecting adjacent battery cells 1 in series. The solder strip 2 has a bottom 21 and opposing side portions 22. In this invention, the bottom 21 of the solder strip 2 refers to the portion of the solder strip 2 facing the battery cell 1 and closest to the battery cell 1 (see [reference]). Figure 6 , Figure 9 and Figure 11 ), and this part can contact and adhere to the surface of the battery cell 1; the side 22 of the solder strip 2 refers to the parts on opposite sides of the bottom 21 of the solder strip 2 (see Figure 6 , Figure 9 and Figure 11 ), and the opposite two sides are respectively connected to the two sides of the bottom 21.

[0042] See also Figure 3 Multiple solder strips 2 are sequentially spaced on each solar cell 1, see [reference]. Figure 5The opposite sides 22 of the welding ribbon 2 are fixed to the surface of the battery cell 1 by adhesive 3. The bottom 21 of the welding ribbon 2 is attached to the surface of the battery cell 1, and no adhesive 3 is provided between the bottom 21 of the welding ribbon 2 and the surface of the battery cell 1. The adhesive 3 can be an insulating adhesive such as hot melt adhesive, thermosetting adhesive, or UV curing adhesive, which can be cured by heat or light to fix the welding ribbon 2 to the battery cell 1.

[0043] Adhesive 3 is commercially available.

[0044] Depend on Figure 2 and Figure 4 As can be seen, the adhesive 3 on the side is continuously arranged along the length of the solder ribbon 2, fixing the solder ribbon 2 to the solar cell 1 from the side. Good fixation of the solder ribbon 2 is achieved through thermosetting or photocuring. Because the solder ribbon 2 is fixed to the solar cell 1 from the side, no adhesive 3 seeps between the bottom 21 of the solder ribbon 2 and the solar cell 1. The bottom 21 of the solder ribbon 2 adheres well to the surface of the solar cell 1, avoiding the problem of incomplete soldering compared to existing dispensing technologies. Furthermore, since adhesive 3 is continuously arranged between the opposite sides 22 of the solder ribbon 2 and the solar cell 1, and the bottom of the solder ribbon 2 is not connected to the outside, even if the adhesive film has high fluidity during subsequent module lamination, it will not penetrate to the bottom of the solder ribbon 2, greatly improving the EL shadow phenomenon during EL testing of photovoltaic modules.

[0045] When selecting solder strip 2, low-temperature solder strip can be used, and the shape is not limited. It can be round, square, irregular, or other shapes. The specific selection should be based on the actual situation.

[0046] Low-temperature solder ribbon refers to solder ribbon with a low welding temperature, below 160℃. The base material of low-temperature solder ribbon can be copper or aluminum, with a coating on the outer wall of the copper base material. The coating includes one or a combination of tin, bismuth, silver, and lead.

[0047] Depend on Figure 5 As can be seen, the solder ribbon 2 selected in this embodiment is circular, that is, the cross-section of the solder ribbon 2 is circular, the bottom 21 of the solder ribbon 2 is tangent to the surface of the battery cell 1 and is in line contact with it, and the distance H1 between the adhesive 3 on both sides of the solder ribbon 2 can be in the range of 0.6DD, where D is the width of the solder ribbon 2. In this example, the width value of the solder ribbon 2 is the diameter of the solder ribbon 2. For example, the distance H1 between the adhesive 3 on both sides in this embodiment is approximately 0.7D.

[0048] In some embodiments, the solar cell 1 may be a gridless solar cell, a tunnel oxide passivated contact solar cell (TOPCon), a heterojunction solar cell (HJT), or a back contact solar cell (XBC), or other types of solar cells may be used.

[0049] The following describes the manufacturing method of the battery string in this embodiment, including the following steps:

[0050] (1) See Figures 1-2 Multiple UV-curable adhesive strips are sequentially and spaced apart on the battery cell 1, leaving a certain space between each two adjacent UV-curable adhesive strips to facilitate the subsequent laying of the solder ribbon 2. The width of the reserved space is related to the specifications and shape of the selected solder ribbon 2. For example, in this embodiment, the solder ribbon 2 is circular, and the width of the reserved space can be between 0.6D and 0.7D. In this embodiment, the width of the reserved space is approximately 0.7D.

[0051] (2) Lay welding strip 2 at the reserved position, such as Figures 3-4 As shown, when laying the welding strip 2, since the UV curing adhesive has not yet cured, a small amount of adhesive may flow towards the bottom of the welding strip 2, but it will not flow to the bottom of the welding strip 2. The welding strip 2 and the battery cell 1 still have excellent adhesion and can still avoid the problem of poor welding.

[0052] (3) UV curing adhesive is cured by ultraviolet light irradiation and the solder strip 2 is fixed to obtain the battery string.

[0053] When the battery strings of this embodiment are applied to photovoltaic modules, the battery strings are arranged in sequence, welded together with busbars, and then an encapsulant film and backsheet are laid, followed by lamination to obtain the photovoltaic module. No EL shadow phenomenon was observed in the photovoltaic module during EL testing.

[0054] The backsheet in a photovoltaic module can be made of glass, polymer film, or other materials.

[0055] In other embodiments, the method for manufacturing the battery string may also employ other methods, such as a method including the following steps:

[0056] (1) Multiple welding strips 2 are laid sequentially and at intervals on the battery cell 1;

[0057] (2) Apply hot melt adhesive to the opposite sides of each welding strip 2. After the hot melt adhesive cools, the welding strip 2 can be fixed to obtain the battery string.

[0058] As can be seen, in the specific preparation of battery strings, the welding ribbon 2 can be laid on the battery cell 1 first, and then adhesive can be applied between the opposite sides 22 of the welding ribbon 2 and the surface of the battery cell 1; or adhesive strips can be printed sequentially and at intervals on the battery cell 1, and a position can be reserved between two adjacent adhesive strips, and then the welding ribbon 2 can be laid at the reserved position so that the opposite sides 22 of the welding ribbon 2 are bonded to the adhesive on the corresponding side.

[0059] In this embodiment, the battery string uses adhesive 3 on opposite sides of the solder ribbon 2 to fix the solder ribbon 2 and the battery cell 1 from the side, preventing the adhesive 3 from entering the bottom of the solder ribbon 2. This ensures that there is no adhesive 3 between the bottom of the solder ribbon 2 and the battery cell 1, avoiding the problem of poor soldering. At the same time, the adhesive 3 is set on opposite sides of the solder ribbon 2 and is continuously set along the length of the solder ribbon 2. The bottom of the solder ribbon 2 is essentially not connected to the outside. When the battery string is applied to a photovoltaic module, after the adhesive film is laminated, even if the adhesive film has high fluidity, it is difficult for the adhesive film to penetrate to the bottom of the solder ribbon 2 and the battery cell 1. When the photovoltaic module is subjected to EL testing, the problem of blackening of the photovoltaic module is greatly improved.

[0060] Example 2

[0061] The battery string of this embodiment includes a plurality of battery cells 1 and a solder strip 2 connected in series with adjacent battery cells 1. The solder strip 2 has a bottom 21 and opposite side portions 22. Multiple solder strips 2 are arranged sequentially and spaced apart on each battery cell 1. The opposite side portions 22 of the solder strip 2 are fixed to the surface of the battery cell 1 by adhesive 3. The bottom 21 of the solder strip 2 is attached to the surface of the battery cell 1, and no adhesive 3 is provided between the bottom 21 of the solder strip 2 and the surface of the battery cell 1. The adhesive 3 on the side is continuously arranged along the length direction of the solder strip 2.

[0062] Adhesive 3 can be a thermosetting adhesive, which is commercially available.

[0063] See Figure 7 In this embodiment, the solder ribbon 2 is a circular solder ribbon with a circular cross-section. The distance H1 between the adhesive 3 on both sides of each solder ribbon 2 can be approximately the diameter D of the solder ribbon 2. There is no adhesive 3 seeping between the bottom of the solder ribbon 2 and the battery cell 1, resulting in good surface adhesion between the solder ribbon 2 and the battery cell 1, thus avoiding the problem of incomplete soldering.

[0064] Example 3

[0065] The battery string of this embodiment includes a plurality of battery cells 1 and a solder strip 2 connected in series with adjacent battery cells 1. The solder strip 2 has a bottom 21 and opposite side portions 22. Multiple solder strips 2 are arranged sequentially and spaced apart on each battery cell 1. The opposite side portions 22 of the solder strip 2 are fixed to the surface of the battery cell 1 by adhesive 3. The bottom 21 of the solder strip 2 is attached to the surface of the battery cell 1, and no adhesive 3 is provided between the bottom 21 of the solder strip 2 and the surface of the battery cell 1. The adhesive 3 on the side is continuously arranged along the length direction of the solder strip 2.

[0066] Adhesive 3 is a hot melt adhesive, which is commercially available.

[0067] See Figures 8-9In this embodiment, the welding strip 2 is an irregularly shaped welding strip with an irregular cross-sectional shape. The welding strip 2 has a lower end with a gradually decreasing width. The bottom 21 of the irregularly shaped welding strip is flat and the flat surface is in surface contact with the surface of the battery cell 1. The adhesive 3 on both sides of the welding strip 2 is tightly attached to the two sides 22 of the welding strip 2.

[0068] In the actual production of battery strings, a better manufacturing method for the irregularly shaped welding strips of this embodiment is to first lay the welding strips on the battery cells, and then apply adhesive to the opposite sides of the welding strips.

[0069] Example 4

[0070] The battery string of this embodiment includes a plurality of battery cells 1 and a solder strip 2 connected in series with adjacent battery cells 1. The solder strip 2 has a bottom 21 and opposite side portions 22. Multiple solder strips 2 are arranged sequentially and spaced apart on each battery cell 1. The opposite side portions 22 of the solder strip 2 are fixed to the surface of the battery cell 1 by adhesive 3. The bottom 21 of the solder strip 2 is attached to the surface of the battery cell 1, and no adhesive 3 is provided between the bottom 21 of the solder strip 2 and the surface of the battery cell 1. The adhesive 3 on the side is continuously arranged along the length direction of the solder strip 2.

[0071] Adhesive 3 is a UV-curable adhesive, commercially available.

[0072] See Figures 10-11 In this embodiment, the welding strip 2 is an irregularly shaped welding strip with an irregular cross-sectional shape. The opposite two sides of the welding strip 2 are parallel to each other. The bottom 21 of the irregularly shaped welding strip is flat and the flat surface is in surface contact with the surface of the battery cell 1. The adhesive 3 on both sides of the welding strip 2 is tightly attached to the two sides 22 of the welding strip 2.

[0073] In the actual production of battery strings, a better manufacturing method for the irregularly shaped welding strip 2 of this embodiment is to first lay the welding strip on the battery cell, and then apply adhesive to the opposite sides of the welding strip.

[0074] In addition to the solder strip shape described in the above embodiments, other shapes of solder strips can also be used, such as square solder strips with a square cross-section, including but not limited to rectangles and squares; irregularly shaped solder strips with an arc bottom can also be used.

[0075] The battery string of the above embodiment has at least the following advantages compared to the conventional battery string:

[0076] (1) The welding strip 2 of the battery string is fixed to the battery cell 1 only by adhesive bonding 3, which simplifies the manufacturing process, reduces welding steps and time required, and lowers costs.

[0077] (2) Compared with the existing dispensing technology, the welding ribbon 2 and the battery cell 1 of the battery string are bonded and fixed by the side of the welding ribbon 2. This not only avoids the problem of poor welding caused by the adhesive 3 entering the bottom of the welding ribbon 2 and the battery cell 1, but also ensures good surface adhesion between the welding ribbon 2 and the battery cell 1, and the welding ribbon 2 and the battery cell 1 are firmly bonded.

[0078] (3) Furthermore, adhesive 3 is provided between the opposite sides of the solder ribbon 2 and the battery cell 1, and the adhesive 3 is continuously provided along the length of the solder ribbon 2. This not only avoids the problem of poor soldering, but also prevents the bottom of the solder ribbon 2 from being connected to the outside world due to the adhesive 3 on both sides. In the subsequent module lamination process, even if the adhesive film has high fluidity, it will not penetrate to the bottom of the solder ribbon 2, which greatly improves the black shadow phenomenon of the module during EL testing.

[0079] In the description of this utility model, it should be understood that the terms "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0080] In addition, in the description of this utility model, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "connection" should be interpreted broadly. For example, they can refer to mechanical connection or electrical connection, or the internal connection of two components. They can be directly connected or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0081] The above embodiments are only used to illustrate the present utility model, and are not intended to limit the present utility model. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present utility model. Therefore, all equivalent technical solutions also fall within the scope of the present utility model. The patent protection scope of the present utility model should be defined by the claims.

Claims

1. A battery string comprising a number of battery segments (1) and a welding strip (2) connecting adjacent said battery segments (1) in series, characterized in that: The welding strip (2) has a bottom (21) and two opposite sides (22), the two opposite sides (22) of the welding strip (2) are fixed with the surface of the battery piece (1) through the adhesive (3), the bottom (21) is in surface contact or line contact with the surface of the battery piece (1), and when the bottom (21) is in line contact with the surface of the battery piece (1), the distance between the two opposite sides of the adhesive (3) of the welding strip (2) is 0.6D-D, wherein D refers to the width of the welding strip (2); when the bottom (21) is in surface contact with the surface of the battery piece (1), the two sides (22) are respectively in close contact with the adhesive (3) on the corresponding side; no adhesive (3) is arranged between the bottom (21) and the surface of the battery piece (1).

2. The battery string of claim 1, wherein, The cross section of the welding strip (2) is circular, square or special-shaped.

3. The battery string of claim 1, wherein, The adhesive (3) is continuously arranged along the length direction of the welding strip (2).

4. The battery string of claim 1, wherein, The adhesive (3) is insulating glue.

5. The battery string of claim 4, wherein, The insulating glue is hot melt glue, heat curing glue or UV curing glue.

6. The battery string of claim 1, wherein, The welding strip (2) is a low-temperature welding strip.

7. The battery string of claim 1, wherein, The battery piece (1) is a main grid-free battery piece.

8. The battery string of claim 1, wherein, The battery piece (1) is a tunnel oxide passivation contact battery piece, a heterojunction battery piece or a back contact battery piece.

9. A photovoltaic module comprising a glue film, a cell string and a back sheet which are sequentially stacked, characterized in that, The battery string adopts the battery string according to any one of claims 1-8.

10. The photovoltaic module of claim 9, wherein, The back plate is a glass back plate or a polymer film back plate.

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