Solar cell and solar cell module

Abstract

According to the solar cell piece and the solar cell assembly provided by the utility model, the length of the bonding pad in the bonding pad group along the second direction is designed to be greater than or equal to the length of the bonding pad along the first direction, so that the bonding pad is changed into a long and narrow structure from an original flat structure, and the bonding pad can be stably connected under the condition that the unit consumption of electrode silver paste of a photovoltaic cell is not increased. Meanwhile, the long and narrow bonding pad can provide more brazing filler metal transmission paths, the tin melting amount on the electrode welding spot is increased, and the welding tension of the welding spot is enhanced. Besides, the bonding pad group can comprise a plurality of bonding pads, in the process of welding the welding strip, if one bonding pad in the bonding pad group is not completely or partially covered by the welding strip, the other bonding pads in the bonding pad group can also be covered by the welding strip, so that the coverage rate of the welding strip is improved, and the reliability of the welding strip is improved. The structure can avoid the quality problems of dislocation and pseudo soldering between the welding strip and the bonding pad group, and ensures that all the fine grid lines can be connected with the welding strip to conduct a circuit.

Description

Technical Field

[0001] The utility model relates to the technical field of solar cell design, in particular to a solar cell sheet and a solar cell assembly. Background Art

[0002] Please refer to Figure 1 Traditional photovoltaic cells use a wide (approximately 1mm) and short (<0.5mm) local solder pad, superimposed with a busbar auxiliary wire electrode design to achieve interconnection between the electrode and the solder ribbon. The length B of the solder pad along the first direction is less than the length A of the solder ribbon along the second direction. Due to the presence of the busbar auxiliary wire, at the interconnection process temperature (above the melting point of the solder on the surface of the solder ribbon), the solder on the surface of the solder ribbon melts into liquid metal, which then flows along the busbar wire and transfers to the solder pad in the electrode. Sufficient solder spreads on the solder pad, and when the soldering interconnection process is complete, a large, protruding solder joint is formed on the pad, making the solder pad effectively secure the solder ribbon.

[0003] The above design presents the following technical issues: First, the solder bumps typically cause localized bulging of approximately 50µm. This means the solder protruding from the top of the ribbon is approximately 50µm thick. This requires thickening the external packaging material to mitigate potential cracking at the solder joints caused by localized stress concentration during the lamination process and in outdoor environments. However, this increased packaging material increases module cost by approximately 1¢ / W. Second, the presence of large solder pads creates shading issues at the solder joints, which can reduce module power by over 2W. Utility Model Content

[0004] The utility model provides a solar cell sheet and a solar cell assembly, which reduce the height of the top of the soldering pad and the light-shielding area of ​​the soldering pad.

[0005] The utility model provides a solar cell, comprising:

[0006] A battery cell body, wherein a plurality of solder pad groups and a plurality of solder ribbons are provided on one surface of the battery cell body, and the plurality of solder ribbons are arranged in parallel along a first direction;

[0007] The pad group includes a pad, and the length of the pad along the second direction is greater than or equal to the length of the pad along the first direction; the solder strip fully or partially covers at least one pad in the pad group; wherein the first direction and the second direction are perpendicular to each other.

[0008] Furthermore, the pads in the pad group are arranged in parallel and equidistantly in the first direction.

[0009] Furthermore, a plurality of fine grid lines are provided on the surface of the battery cell body;

[0010] A plurality of the fine gate lines are arranged in parallel along the second direction, and each of the pads in the pad group is connected to the fine gate line.

[0011] Furthermore, at least one pad in the pad group is connected to a plurality of the fine gate lines.

[0012] Furthermore, a ratio of a length of at least one of the pads in the pad group along the second direction to a length of the pad along the first direction is ≥1 / 5.

[0013] Furthermore, the remaining pads in the pad group are arranged on both sides of the pad with the largest volume in the pad group.

[0014] Furthermore, the shape of the pad is a regular pattern

[0015] Furthermore, the shape of the pad is irregular.

[0016] Furthermore, the number of pads in the pad group is greater than or equal to 4.

[0017] Furthermore, the height of the solder joint protruding from the top of the solder strip is less than or equal to 20 μm.

[0018] The utility model also discloses a solar cell assembly, which adopts the above-mentioned solar cell sheets, and the solar cell sheets are connected by the welding strips.

[0019] Compared with the prior art, the present invention has at least the following technical effects:

[0020] In the present invention, the length of the pads in the pad group along the second direction is designed to be greater than or equal to the length of the pads along the first direction, so that the pads are changed from the original flat structure to a narrow and long structure. When the unit consumption of the electrode silver paste of the photovoltaic cell does not increase, the shading problem of the electrode exposed to the welding strip is reduced. At the same time, the narrow and long pads can provide more solder transmission paths, increase the amount of molten tin on the electrode solder joint, and strengthen the welding tension of the solder joint. In addition, the pad group in the present invention can be configured to include multiple pads. During the process of soldering the solder strip, if one of the pads in the pad group is not fully or partially covered by the solder strip, the remaining pads in the pad group can also be covered by the solder strip, thereby improving the coverage rate of the solder strip. This structure can avoid the quality problems of misalignment and cold soldering between the solder strip and the pad group, and ensure that all fine grid lines can conduct the circuit with the solder strip. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the pad in the background technology;

[0022] Figure 2 This is a structural diagram of a welding pad in one embodiment of the present utility model;

[0023] Figure 3 FIG. 2 is another structural diagram of a soldering pad in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The following description of a solar cell and solar cell assembly according to the present invention is combined with schematic diagrams, which illustrate preferred embodiments of the present invention. It should be understood that those skilled in the art may modify the present invention described herein while still achieving the beneficial effects of the present invention. Therefore, the following description should be understood as a general guideline for those skilled in the art and is not intended to limit the present invention.

[0025] The following paragraphs describe the present invention in more detail by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are greatly simplified and not to exact scale, and are intended solely to facilitate and clearly illustrate the embodiments of the present invention.

[0026] Please refer to Figure 2 and Figure 3 This embodiment discloses a solar cell. Specifically, the solar cell includes: a cell body, a plurality of solder pads and a plurality of solder ribbons 2 disposed on one surface of the cell body, the plurality of solder ribbons 2 being arranged in parallel along a first direction; a solder pad group 1 including solder pads, wherein the length of the solder pads along a second direction is greater than or equal to the length of the solder pads along the first direction; the solder ribbon fully or partially covering at least one solder pad within the solder pad group 1; wherein the first direction and the second direction are perpendicular to each other.

[0027] In this embodiment, the first direction is along the length direction of the battery cell body, and the second direction is along the width direction of the battery cell body, that is, the pads in the pad group 1 are arranged in parallel along the length direction of the battery cell body.

[0028] In this embodiment, the length of the pads in the pad group 1 along the second direction is designed to be greater than or equal to the length of the pads along the first direction, so that the pads are changed from the original flat structure to a narrow and long structure. When the unit consumption of the electrode silver paste of the photovoltaic cell does not increase, the shading problem of the electrode exposed to the welding strip 2 is reduced. At the same time, the narrow and long pads can replace the main grid, provide more solder transmission paths, increase the amount of molten tin on the electrode solder joint, and strengthen the welding tension of the solder joint. In addition, the pad group 1 in the present invention can be configured to include multiple pads. During the process of soldering the solder strip 2, if one of the pads is not fully or partially covered by the solder strip 2, the remaining pads in the pad group 1 can also be covered by the solder strip 2. This structure can avoid the quality problems of misalignment and cold soldering between the solder strip 2 and the pad group 1, and ensure that all fine grid lines 3 can conduct the circuit with the solder strip 2.

[0029] In this embodiment, the pads in the pad group 1 are arranged parallel and equidistantly in the first direction, and the distance between the pads can be set according to actual conditions and is not limited here. If the pad group 1 includes multiple pads, that is, when it is a split pad, the pad group 1 has a pad body, which has a larger volume than the remaining pads in the pad group 1, and the remaining small pads are arranged on both sides of the pad body in sequence. The number of pads in the pad group 1 should not be too many. Too many pads may reduce the light blocking rate and increase the string resistance. Therefore, in this embodiment, the number of pads in the pad group 1 is set to be greater than or equal to 4, for example, 3, 2 and 1.

[0030] In this embodiment, the cell body is made of silicon wafers and is used to convert solar energy into electrical energy. The cell body is a rectangular flat plate structure; the solder on the surface of the solder ribbon 2 melts at high temperature and becomes liquid metal to form solder, which transfers the liquid metal along the second direction of one of the solder pads in the solder pad group 1 disclosed in this embodiment and the fine grid line 3. Generally speaking, the surface of the solder pad can be used to carry the flowing solder. The optimal situation is that the position of the solder pad along the second direction of the solder pad body is near the center line of the solder pad itself for carrying the flowing solder. Of course, if the solder ribbon 2 is offset along the first direction during the manufacturing process, the rest of the solder pad can also be used to carry the flowing solder. In addition, the length of the solder ribbon 2 along the first direction is designed for the formation of solder joints to fix the solder ribbon 2. Therefore, the solder pad disclosed in this embodiment can not only assume the function of transmitting solder, but also assume the function of fixing the solder ribbon 2 at the solder joint.

[0031] Further, in the embodiment, the pads in the pad group 1 are arranged in parallel and equidistant in the first direction. The ratio of the length of at least one pad in the pad group 1 in the second direction to the length of the pad in the first direction is greater than or equal to 1 / 5, for example, 1 / 6, 1 / 7, or 1 / 8, etc. The length of the pad in the second direction and the length of the pad in the first direction are not specifically limited here. Preferably, the pad with the largest volume in the pad group 1, i.e., the pad main body, has the above length ratio. (If each pad group 1 includes only one pad, the length ratio of the pad is designed to be the above ratio.) The ratio of the length of the remaining pads in the second direction to the length of the pad in the first direction is not specifically limited here, as long as the length of the pad in the second direction is greater than or equal to the length of the pad in the first direction. Those skilled in the art can make specific choices according to the width of the solder strip 2, the width of the pad, and the process processing conditions, etc.

[0032] It can be understood that, in the optimal case, the pad main body (the ratio of the length of the pad in the second direction to the length of the pad in the first direction is greater than or equal to 1 / 5) is used to carry the flowing solder near the position of the center line of the pad in the second direction. Of course, if the solder strip 2 is offset in the first direction during the manufacturing process, the remaining pads can also be used to carry the flowing solder.

[0033] It can be understood that, during the welding process, the solder on the surface of the solder strip melts at high temperature, and the melted solder covers the pads on the surface of the battery. When the solder covering the pads cools and solidifies, a firm solder joint is formed on the surface of the pad, thereby realizing reliable electrical and mechanical connection of the solder strip and the pad.

[0034] In the embodiment, the pad group 1 having the above structure is used, and the height of the solder joint formed after the solder solidifies protruding from the top of the solder strip is reduced from 50 um to 20 um or less. Furthermore, the pad having the above structure can reduce the light shielding of the pad by 70% or more and reduce the unit consumption of silver paste of the main grid electrode by 50% or more.

[0035] It can be understood that the solar cell also includes a fine grid line 3, which functions as a circuit conductor. The fine grid line 3 is formed on one side of the cell body by printing silver paste. A plurality of the fine grid lines 3 are arranged in parallel in the second direction, and the fine grid line 3 extends in the first direction. The line width of the fine grid line 3 is 20 um-50 um, and specifically, the line width of the fine grid line 3 includes but is not limited to 21 um, 25 um, and 45 um.

[0036] In this embodiment, each of the pads in the pad group 1 is connected to the fine grid lines 3. Depending on the length of the pad along the second direction, the pad can be connected to multiple or one fine grid lines 3. Specifically, please refer to the figure, the pad body is connected to three fine grid lines, and the remaining pads are respectively connected to one fine grid line 3. Of course, those skilled in the art can select the number of fine grid lines 3 connected to each pad in each pad group 1 according to actual conditions, such as three, four, five, or other numbers. The specific selection can be adaptively made based on the length of the pad, the spacing between the fine grid lines 3, the processing technology of the pad, and the like.

[0037] By directly connecting the fine grid lines 3 through the pads, compared with the structure of the main fine grid lines and the vertical intersection of the fine grid lines in the prior art, the main fine grid lines are eliminated, which is beneficial to reducing the consumption of silver paste of the fine grid line material and reducing material costs.

[0038] Furthermore, in this embodiment, the shape of the pad can be regular or irregular, for example, circular, triangular or rectangular, preferably rectangular; or other irregular shapes are also possible.

[0039] In summary, the length of the pad along the second direction provided in this embodiment is greater than or equal to the length of the pad along the first direction, so that the pad changes from the original flat structure to a narrow and long structure. When the unit consumption of the electrode silver paste of the photovoltaic cell does not increase, the shading problem of the electrode exposed to the welding strip 2 is reduced. At the same time, the narrow and long pad can provide more solder transmission paths, increase the amount of molten tin on the electrode solder joint, and strengthen the welding tension of the solder joint. In addition, the pad can not only serve as the main grid to transfer solder, but also be used to form solder joints and fix the welding strip 2, eliminating the setting of the main fine grid line, which is conducive to reducing the consumption of silver paste of the fine grid line material and reducing material costs. Furthermore, the pad group 1 in the present invention can be configured to include multiple pads. During the process of welding the welding ribbon 2, if one of the pads is not fully or partially covered by the welding ribbon 2, the remaining pads in the pad group 1 can also be covered by the welding ribbon 2, thereby improving the coverage rate of the welding ribbon 2. This structure can avoid quality problems such as misalignment and cold soldering between the welding ribbon 2 and the pad group 1, and ensure that all fine grid lines 3 can conduct circuits with the welding ribbon 2.

[0040] Example 2

[0041] This embodiment discloses a photovoltaic cell, comprising the solar cell disclosed in the first embodiment, wherein a plurality of the solar cell cells are connected by the welding ribbon 2. The photovoltaic cell disclosed in the first embodiment also has the same technical effects as the photovoltaic cell disclosed in the first embodiment, and will not be described in detail here.

[0042] Specifically, two adjacent solar cell slices are connected by a welding ribbon 2, and the multiple pads in the welding pad group 1 are welded and fixed to the welding ribbon 2. Specifically, each solar cell slice includes multiple welding pad groups 1 and multiple welding ribbons 2. During welding, each welding ribbon 2 is welded and fixed to the multiple welding pad groups 1.

[0043] Obviously, those skilled in the art may make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A solar cell, characterized in that: include: A battery cell body, wherein a plurality of solder pad groups and a plurality of solder strips are provided on one surface of the battery cell body, and the plurality of solder strips are arranged in parallel along a first direction; The pad group includes a pad, and the length of the pad along the second direction is greater than or equal to the length of the pad along the first direction; the solder strip fully or partially covers at least one pad in the pad group; wherein the first direction and the second direction are perpendicular to each other.

2. The solar cell according to claim 1, wherein: The plurality of pads in the pad group are arranged in parallel and equidistantly in a first direction.

3. The solar cell according to claim 1 or 2, wherein: The surface of the battery cell body is also provided with a plurality of fine grid lines; A plurality of the fine gate lines are arranged in parallel along the second direction, and each of the pads in the pad group is connected to the fine gate line.

4. The solar cell according to claim 3, wherein: At least one pad in the pad group is connected to a plurality of the fine gate lines.

5. The solar cell according to claim 1, wherein: The ratio of the length of at least one pad in the pad group along the second direction to the length of the pad along the first direction is ≥ 1 / 5。 6. The solar cell according to claim 1, wherein: The remaining pads in the pad group are respectively arranged on both sides of the pad with the largest volume in the pad group.

7. The solar cell according to claim 1, wherein: The shape of the pad is a regular pattern.

8. The solar cell according to claim 1, wherein: The shape of the pad is an irregular pattern.

9. The solar cell according to claim 1, wherein: The number of pads in the pad group is greater than or equal to 4.

10. The solar cell according to claim 1, wherein: The height of the solder joint protruding from the top of the solder strip is less than or equal to 20 μm.

11. A solar cell module, characterized in that: The solar cell comprises the solar cell according to any one of claims 1 to 10, wherein the solar cell cells are connected by the welding ribbon.

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