Back contact solar cell, photovoltaic module and photovoltaic system

Abstract

The invention provides a back contact solar cell, a photovoltaic module and a photovoltaic system, and relates to the technical field of photovoltaics. The battery comprises a battery body and an electrode structure located on the back side of the battery body. According to the electrode structure, first electrode disc columns and second electrode disc columns extend in the second direction and are alternately distributed in the first direction; the first electrode disc row comprises a plurality of first electrode discs which are arranged in rows in the second direction, and the first electrode discs are electrically connected with the N-type grid lines; the second electrode disc row comprises a plurality of second electrode discs which are arranged in rows in the second direction, and the second electrode discs are electrically connected with the P-type grid lines; in the second direction, the battery body comprises a plurality of areas, and the area of the second electrode disc in the same area is larger than that of the first electrode disc. According to the invention, the bonding area of the second electrode disc and the interconnector is increased, and the bonding force of the second electrode disc and the interconnector is further enhanced, so that the second electrode disc and the interconnector are firmly bonded, the risk of pulling-off basically does not exist, and the electrical connection is more reliable.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and particularly to a back-contact solar cell, a photovoltaic module, and a photovoltaic system. Background Art

[0002] The electrode structures of back-contact solar cells are all located on the back side of the cell, and there is no electrode shielding on the front side. Therefore, back-contact solar cells have higher short-circuit current and photoelectric conversion efficiency, and are one of the technical directions for realizing high-efficiency crystalline silicon cells at present.

[0003] In a photovoltaic module, the pad in a back-contact solar cell is an important component for conducting the fine grid and the solder strip to collect current. In the prior art, the pad is prone to problems such as pulling off and separating from the solder strip. Summary of the Invention

[0004] The present invention provides a back-contact solar cell, a photovoltaic module, and a photovoltaic system, aiming to solve the problem of poor connection reliability between the pad and the solder strip.

[0005] In the first aspect of the present invention, a back-contact solar cell is provided, including: a cell body and an electrode structure located on the back side of the cell body;

[0006] The electrode structure includes: an N-type grid line, a P-type grid line, a first electrode pad row, and a second electrode pad row;

[0007] Both the N-type grid line and the P-type grid line extend along a first direction and are alternately distributed along a second direction; the first direction is different from the second direction;

[0008] Both the first electrode pad row and the second electrode pad row extend along the second direction and are alternately distributed along the first direction; the first electrode pad row includes: a plurality of first electrode pads arranged in a column along the second direction, and the first electrode pad is electrically connected to the N-type grid line; the second electrode pad row includes: a plurality of second electrode pads arranged in a column along the second direction, and the second electrode pad is electrically connected to the P-type grid line;

[0009] Along the second direction, the cell body includes a plurality of regions, and in the same region, the area of the second electrode pad is larger than the area of the first electrode pad.

[0010] In practical applications, it is found that there is an easy risk of pulling-off between the electrode plate and the interconnecting member. The main reason is that there is a first doping layer at the position corresponding to the N-type grid line and the first electrode plate on the battery body, and there is a second doping layer at the position corresponding to the P-type grid line and the second electrode plate on the battery body. The difference between the doping materials and doping concentrations of the first doping layer and the second doping layer makes the position of the second electrode plate easier to pull off and separate compared to the first electrode plate. In the present application, along the second direction, in the same area, the area of the second electrode plate is designed to be larger than the area of the first electrode plate; in the same area, through the larger area of the second electrode plate, the bonding area between the second electrode plate, the interconnecting member and the battery body is increased, thereby enhancing the bonding force between the second electrode plate, the interconnecting member and the battery body, so as to reduce the risk of solder strip pulling-off caused by the unbalanced bonding force between the first and second electrode plates.

[0011] In a second aspect of the present invention, there is provided a photovoltaic module, comprising: a plurality of any one of the aforementioned back-contact solar cells, and an interconnecting member connecting adjacent back-contact solar cells, the interconnecting member being fixed to the previous battery body through the first electrode plate, and the interconnecting member being fixed to the subsequent battery body through the second electrode plate;

[0012] On one interconnecting member, the total area of the first electrode plates fixed thereto is smaller than the total area of the second electrode plates fixed thereto.

[0013] In a third aspect of the present invention, there is provided a photovoltaic system, comprising: a plurality of any one of the aforementioned photovoltaic modules.

[0014] The above-mentioned photovoltaic module and photovoltaic system have the same or similar beneficial effects. To avoid repetition, they will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0016] Figures 1 to 6 FIG. shows partial structural schematic diagrams of several back-contact solar cells in the embodiments of the present invention;

[0017] Figure 7 FIG. shows a partial structural schematic diagram of a photovoltaic module in the embodiments of the present invention.

[0018] Description of the reference numerals in the drawings:

[0019] 1 - Battery body, 11 - N - type grid line, 12 - P - type grid line, 13 - First electrode plate, 131 - Edge first electrode plate, 132 - Intermediate first electrode plate, 133 - Transition first electrode plate, 14 - Second electrode plate, 141 - Edge second electrode plate, 142 - Intermediate second electrode plate, 143 - Transition second electrode plate, 15 - N - type doped region, 16 - P - type doped region, 17 - Interface dielectric layer, 18 - Isolation region, 19 - Substrate, 22 - Interconnecting member, 221 - First part, 222 - Second part, 23 - Insulating member. Detailed implementation manner

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0021] The present invention provides a back - contact solar cell and a photovoltaic module. The photovoltaic module includes a plurality of back - contact solar cells provided in this application, and the number of back - contact solar cells in the photovoltaic module is not limited. The photovoltaic module may further include encapsulation adhesive films on opposite sides of the back - contact solar cells, etc., and other structures in the photovoltaic module are not specifically limited. Refer to Figures 1 to 7 , the back - contact solar cell includes: a battery body 1 and an electrode structure located on the back side of the battery body 1. The electrode structure is used to collect and conduct current. The battery body contains a PN junction, which can separate carriers. During the normal operation of the back - contact solar cell, the side of the battery body that mainly receives light is the light - facing side, and the back - light side is opposite to the light - facing side. Figures 1 to 7The middle part mainly shows the structure on the back side of the battery body 1. The electrode structure includes: an N-type grid line 11, a P-type grid line 12, a first electrode disk column, and a second electrode disk column; the N-type grid line 11 refers to an N-type current collecting grid line, and the P-type grid line 12 refers to a P-type current collecting grid line for collecting carriers or current in the battery body. The N-type grid line 11 and the P-type grid line 12 extend along the first direction L1 and are alternately distributed along the second direction L2. For example, in the second direction L2, one N-type grid line 11 is followed by one P-type grid line 12, and then one N-type grid line 11 is distributed like this. The first electrode disk column and the second electrode disk column extend along the second direction L2 and are alternately distributed along the first direction L1. For example, in the first direction L1, one first electrode disk column is followed by one second electrode disk column, and then one first electrode disk column is distributed like this. The first direction L1 is different from the second direction L2, and the angle between the first direction L1 and the second direction L2 is not specifically limited. For example, they can be perpendicular to each other. The first electrode disk column includes a plurality of first electrode disks 13 arranged in columns along the second direction L2. The number of first electrode disks 13 in the first electrode disk column is not limited. The first electrode disk 13 is electrically connected to the N-type grid line 11 to realize the collection and conduction of current or carriers. The second electrode disk column includes a plurality of second electrode disks 14 arranged in columns along the second direction L2. The number of second electrode disks 14 in the second electrode disk column is not limited. The second electrode disk 14 is electrically connected to the P-type grid line 12 to realize the collection and conduction of current or carriers. Along the second direction L2, the battery body includes multiple regions. Each region covers the total size of the battery body in the first direction L1. Or rather, the sizes of the respective regions in the first direction L1 are equal. The relative sizes of the respective regions are not limited, mainly the sizes covered by the respective regions in the second direction L2 are not limited, and the number of regions included in a battery body is not limited. The area of the second electrode disk in the same region refers to the area of one second electrode disk 14 in the same region. The area of the first electrode disk in the same region refers to the area of one first electrode disk 13 in that region. The area of the first electrode disk and the area of the second electrode disk mentioned in this application both refer to the area of the surface of the electrode disk facing away from the battery body.

[0022] Due to the different doping types of the N-type doping region and the P-type doping region, as well as possible differences in thickness, doping concentration, width, etc., the first electrode pad 13 and the second electrode pad 14 exhibit different bonding forces during the conductive interconnection of the photovoltaic module. Through big data aggregation, it is found that the bonding force of the first electrode pad 13 is mainly higher and the bonding force of the second electrode pad 14 is lower, which is likely to cause an imbalance in the bonding force between the first and second electrode pads, and risks such as pulling off are likely to occur at the position of the second electrode pad 14. Therefore, to address the above problems, in this application, the area of the second electrode pad in the same region is larger than the area of the first electrode pad. The area of the electrode pad here is the area of the surface of the electrode pad facing away from the battery body, and this area is approximately the area where the electrode pad is connected to the battery body and electrically connected to the interconnecting member. By setting the second electrode pad to have a larger area in the same region, the attachment area between the second electrode pad and the battery body and the bonding area with the interconnecting member can be increased, thereby enhancing the bonding force between the solar cell and the interconnecting member, making the connection between the two firm, and basically eliminating the risk of pulling off, and the electrical connection is more reliable.

[0023] It should be noted that the electrode pad here can be a solder pad, etc., and the interconnecting member here can be a solder ribbon, a conductive backplane, etc. For example, if the electrode pad is a solder pad and the interconnecting member is a solder ribbon, then by the larger area of the second electrode pad in the same region, the bonding area between the second electrode pad and the solder ribbon and the battery body is increased, thereby enhancing the welding force between the second electrode pad and the interconnecting member, making the connection between the two firm, and basically eliminating the risk of pulling off, and the electrical connection is more reliable.

[0024] The total area of the second electrode pads 14 in the second electrode pad column is the sum of the areas of the surfaces of all the second electrode pads 14 in the second electrode pad column facing away from the battery body. The total area of all the first electrode pads 13 in the first electrode pad column is the sum of the areas of the surfaces of all the first electrode pads 13 in the first electrode pad column facing away from the battery body. In some embodiments, the total area of the second electrode pads in the second electrode pad column is larger than the total area of the first electrode pads in the first electrode pad column. By the larger total area of the second electrode pads in the second electrode pad column, the overall bonding area and bonding force between an interconnecting member and the battery body can be increased, thereby making the connection between the two firm, and basically eliminating the risk of pulling off, and the electrical connection is more reliable.

[0025] For example, referring to Figure 1 , along the first direction L1, the left side is the first electrode pad column, the middle is the second electrode pad column, and the right side is the first electrode pad column. The total area of the second electrode pads 14 in the middle second electrode pad column is larger than the total area of the first electrode pads 13 in the left first electrode pad column. The total area of the second electrode pads 14 in the middle second electrode pad column is also larger than the total area of the first electrode pads 13 in the right first electrode pad column.

[0026] It should be noted that the total area of the second electrode disks in the second electrode disk column in this application can be the total area of the second electrode disks in any second electrode disk column in a back-contact solar cell. The determination method of the total area of the first electrode disks in the first electrode disk column in this application is the same, and to avoid repetition, it will not be elaborated here. In this application, for the determination method of the total area, those not specifically described are similar or the same, and to avoid repetition, it will not be elaborated later.

[0027] In some embodiments, in the second direction L2, the battery body includes: two relatively distributed edge regions, and an intermediate region located between the two edge regions. The relative sizes of the edge regions and the intermediate region are not limited here. In the second direction L2, the battery body includes: two relatively distributed edges. Here, the edge regions can refer to the regions close to the above-mentioned edges. For example, Figure 1 in, the two edges here refer to the upper edge and the lower edge of the battery body. The first electrode disks in the first electrode disk column located in the edge regions are the edge first electrode disks 131, and the first electrode disks located in the intermediate region are the intermediate first electrode disks 132. The area of the edge first electrode disks 131 is larger than the area of the intermediate first electrode disks 132. Specifically, in the edge regions in the second direction L2, it is the position where the back-contact solar cell starts to be electrically connected to the interconnecting member. The connection reliability of the above-mentioned edge regions has a greater impact on the connection effect. In this application, the area of the edge first electrode disks 131 in the first electrode disk column located in the edge regions is larger. By increasing the contact area to improve the bonding force in the edge regions, reliable connection in the edge regions can be ensured; in addition, the intermediate region is the central position where the back-contact solar cell is electrically connected to the interconnecting member. The connection reliability of the intermediate region has a relatively smaller impact on the connection effect. In this application, by appropriately reducing the area of the intermediate first electrode disks 132 in the first electrode disk column located in the intermediate region, not only can the bonding force in the intermediate region still be ensured, but also material waste can be avoided and the cost can be reduced.

[0028] In some embodiments, the second electrode disks in the second electrode disk column located in the edge regions are the edge second electrode disks 141, and the second electrode disks located in the intermediate region are the intermediate second electrode disks 142. The area of the edge second electrode disks 141 is larger than the area of the intermediate second electrode disks 142. Similarly, the area of the edge second electrode disks 141 in the second electrode disk column located in the edge regions is larger. By increasing the contact area to improve the bonding force in the edge regions, reliable connection in the edge regions can be ensured, and material waste can also be avoided and the cost can be reduced.

[0029] It should be noted that in this application, the area of the first edge electrode disk 131 can be the area of the surface of any first edge electrode disk 131 facing away from the battery body in the back-contact solar cell. In this application, the determination methods of the areas of the intermediate first electrode disk 132, the edge second electrode disk 141, and the intermediate second electrode disk 142 are similar or the same as this, and for the sake of avoiding repetition, they will not be elaborated here. In this application, for the determination methods of areas, those without special instructions are similar or the same as this, and for the sake of avoiding repetition, they will not be elaborated hereinafter.

[0030] In some embodiments, in the edge region, the total area of the second electrode disks in a second electrode disk row is greater than the total area of the first electrode disks in a first electrode disk row. It can be understood that the total area of all the edge second electrode disks 141 in a second electrode disk row is greater than the total area of all the edge first electrode disks 131 in a first electrode disk row. By increasing the total area of the edge second electrode disks 141 in the second electrode disk row, in the edge region, the contact area between the edge second electrode disks 141 and the interconnecting member and the battery body is increased, thereby improving the bonding force difference between the edge second electrode disks 141 and the edge first electrode disks in the edge region and enhancing the connection reliability of the interconnecting member. The total area of all the edge second electrode disks 141 in the second electrode disk row refers to the sum of the areas of the surfaces of all the edge second electrode disks 141 facing away from the battery body in a second electrode disk row; the total area of all the edge first electrode disks 131 in the first electrode disk row is similar to this, and for the sake of avoiding repetition, it will not be elaborated here.

[0031] In some embodiments, the area of the edge second electrode disk 141 is greater than the area of the edge first electrode disk 131. In the edge region, the contact area between the edge second electrode disks 141 and the interconnecting member and the battery body is increased, thereby enhancing the bonding force between the edge second electrode disks 141 and the interconnecting member and the battery body in the edge region and improving the bonding force difference between the edge second electrode disks and the edge first electrode disks.

[0032] In some embodiments, in the intermediate region, the total area of the second electrode disks in a second electrode disk row is greater than the total area of the first electrode disks in a first electrode disk row. It can be understood that the total area of all the intermediate second electrode disks 142 in a second electrode disk row is greater than the total area of all the intermediate first electrode disks 132 in a first electrode disk row. In the intermediate region, by increasing the total area of all the intermediate second electrode disks 142 in the second electrode disk row, the contact area between the intermediate second electrode disks 142 and the interconnecting member and the battery body in the intermediate region is increased, thereby improving the bonding force difference between the intermediate second electrode disks 142 and the intermediate first electrode disks in the intermediate region and enhancing the connection reliability of the interconnecting member.

[0033] In some embodiments, the ratio of the length to the width of the edge second electrode pad 141 is C, and the ratio of the length to the width of the middle second electrode pad 142 is D; the number of the middle second electrode pads 142 is more than 9 times that of the edge second electrode pads 141, C is less than D, and D is greater than 3C. That is to say, the ratio C of the length to the width of the edge second electrode pad 141 is smaller, and the edge second electrode pad 141 is more likely to have a length and width that are approximately equal. The ratio D of the length to the width of the middle second electrode pad 142 is larger, and the shape of the middle second electrode pad 142 is more likely to be elongated, and D is greater than 3C. In the edge region in the second direction L2, it is the position where the interconnecting member makes an initial electrical connection with the back-contact solar cell. The reliability of the connection in the above-mentioned edge region has a greater impact on the connection effect. The middle region is the central position where the interconnecting member is electrically connected to the back-contact solar cell, and the requirement for the current transmission function is greater than the requirement for connection reliability. The ratio C of the length to the width of the edge second electrode pad 141 is smaller, and the edge second electrode pad 141 has a larger combined area with the interconnecting member in all directions, and the connection in the edge region is more reliable. At the same time, when D is less than or equal to 3C, it may cause the width of the middle second electrode pad 142 to be too large. In the middle region, the combined area of the interconnecting member and the second electrode pad is too large, which may result in waste, higher cost, and more shading. When D is greater than 3C, the width of the middle second electrode pad 142 is appropriate. In the middle region, the combined area of the interconnecting member and the second electrode pad is more appropriate, and the bonding force between the middle second electrode pad 142 and the interconnecting member is more appropriate, and it can play a better role in current transmission at the same time. The number of the middle second electrode pads is more than 9 times that of the edge second electrode pads. In the middle region, there are more bonding points between the interconnecting member and the second electrode pads, and more current convergence points, which can improve the current transmission efficiency.

[0034] For example, the ratio of the length to the width of the edge second electrode pad 141 is C, and the ratio of the length to the width of the middle second electrode pad 142 is D; C is less than D, and D can be 3.1C, 3.3C, 3.5C, 3.8C, 3.9C, 4C, 4.1C, 4.2C, 4.4C, 4.5C, 4.7C, 4.8C, 5C, 5.5C, 6C; for example, the number of the middle second electrode pads 142 is 9 times, 9.5 times, 10 times, 10.5 times, 11 times, 11.5 times, 12 times that of the edge second electrode pads 141.

[0035] In some embodiments, the battery body further includes a transition region located between the edge region and the middle region, that is, in the second direction L2, the transition region is located between the edge region and the middle region; the first electrode disk in the first electrode disk column located in the transition region is the transition first electrode disk 133, and the area of the transition first electrode disk 133 is between the area of the edge first electrode disk 131 and the area of the middle first electrode disk 132. That is to say, the area of one transition first electrode disk 133 is smaller than the area of one edge first electrode disk 131 and larger than the area of one middle first electrode disk 132. In this application, by providing the transition first electrode disk 133 with an area between the area of the edge first electrode disk 131 and the area of the middle first electrode disk 132 in the transition region between the middle region and the edge region, it is possible to ensure a gradual transition of the first electrode disk bonding force, increase the flexibility of the interconnection design, and provide an effective current collection ability.

[0036] The length and width of the electrode disk refer to the length and width of the surface of the electrode disk facing away from the battery body. The length can be greater than or equal to the width, where the length is parallel to the first direction L1 and the width is parallel to the second direction L2. The dimensions of the electrode disk mentioned in this application are the same as the definitions here unless otherwise specified, and will not be repeated to avoid redundancy.

[0037] There is no limitation on the dimensions of the first electrode disk 13 and the second electrode disk 14. For example, along the second direction L2, the widths of the first electrode disk 13 and the second electrode disk 14 can be selected from 130μm, 150μm, 180μm, 190μm, 200μm, 210μm, 220μm, 230μm, 240μm, 250μm, 270μm, 300μm, and along the first direction L1, the lengths of the first electrode disk 13 and the second electrode disk 14 can be selected from 500μm, 600μm, 800μm, 900μm, 1000μm, 1050μm, 1100μm, 1200μm, 1300μm, 1400μm, 1500μm.

[0038] In the second direction L2, the dimensions of the intervals between adjacent first electrode disks 13 and between adjacent second electrode disks 14 can be 800μm, 810μm, 830μm, 850μm, 860μm, 900μm, 910μm, 940μm, 950μm, 990μm, 1000μm, 1000μm, 1100μm, 1200μm, 1300μm, 1400μm, 1500μm.

[0039] In some embodiments, the second electrode disk in the second electrode disk column located in the transition region is the transition second electrode disk 143( Figures 1 to 3As shown by the red wireframe, the area of the transitional second electrode disk 143 is between the area of the edge second electrode disk 141 and the area of the middle second electrode disk 142, which can also ensure a reasonable and slow transition of the bonding force between the second electrode disk, the interconnecting member, and the battery body, increase the elasticity of the interconnect design, and provide an effective current collection ability.

[0040] In some embodiments, the length of a transitional first electrode disk 133 can be 0.8 to 1.2 mm, such as 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, 1 mm, 1.05 mm, 1.1 mm, 1.15 mm, 1.2 mm, and the width of a transitional first electrode disk 133 can be selected from 0.2 mm to 0.3 mm, such as 0.2 mm, 0.22 mm, 0.24 mm, 0.25 mm, 0.26 mm, 0.27 mm, 0.3 mm, where the length is parallel to the first direction L1 and the width is parallel to the second direction L2. For example, the dimensions of a transitional first electrode disk 133 include at least one of the following five: 1 mm × 0.25 mm, 0.9 mm × 0.21 mm, 1 mm × 0.21 mm, 1 mm × 0.3 mm, 0.9 mm × 0.21 mm. The transitional first electrode disk 133 with the above dimensions has a good electrical connection effect and is easy to fabricate.

[0041] In some embodiments, in the transitional region: the total area of the second electrode disks in a second electrode disk row is greater than the total area of the first electrode disks in a first electrode disk row. It can be understood that: in the transitional region, the total area of the respective transitional second electrode disks 143 in a second electrode disk row is greater than the total area of the respective transitional first electrode disks 133 in a first electrode disk row. In the transitional region, the contact area between the transitional second electrode disks 143 and the interconnecting member and the battery body is increased, thereby improving the bonding force of the transitional second electrode disks 143 in the transitional region, improving the bonding force difference between the transitional second electrode disks 143 and the first electrode disks in the transitional region, and improving the overall bonding force difference between the P region and the N region, thus improving the connection reliability of the interconnecting member on the battery chip.

[0042] It should be noted that in a first electrode disk row, the respective quantities of the edge first electrode disk 131, the transitional first electrode disk 133, and the middle first electrode disk 132 are not specifically limited, and the magnitude relationship between the quantities is not specifically limited either.

[0043] In some embodiments, in a first electrode pad column, the number of transitional first electrode pads 133 is between the number of edge first electrode pads 131 and the number of middle first electrode pads 132, and the number of middle first electrode pads 132 is greater than the number of edge first electrode pads 131. The number of middle first electrode pads 132 with the smallest area is the largest, which can save materials and reduce costs. At the same time, through the transition of an appropriate number of transitional first electrode pads 133, the bonding force can be further ensured to be uniform, and the flexibility of the interconnection design can be increased and the effective current collection ability can be provided.

[0044] For example, Figures 1 to 3 in, in a first electrode pad column, the number of edge first electrode pads 131 is 2, the number of transitional first electrode pads 133 is 8, and the number of middle first electrode pads 132 is 11.

[0045] It should be noted that in a second electrode pad column, the numbers of the edge second electrode pads 141, the transitional second electrode pads 143, and the middle second electrode pads 142 are not specifically limited, and the magnitude relationships between the numbers are not specifically limited either.

[0046] In some embodiments, in a second electrode pad column, the number of transitional second electrode pads 143 is between the number of edge second electrode pads 141 and the number of middle second electrode pads 142, and the number of middle second electrode pads 142 is greater than the number of edge second electrode pads 141. Similarly, materials can be saved and costs can be reduced. At the same time, through the transition of an appropriate number of transitional second electrode pads 143, the bonding force can be further ensured to be uniform, and the flexibility of the interconnection design can be increased and the effective current collection ability can be provided.

[0047] When the sizes of the second electrode pads in the three regions of the edge region, the middle region, and the transitional region are all larger than those of the first electrode pads, the bonding force of the interconnection components corresponding to the entire P region can be improved as a whole, the difference in the bonding force between the P section and the N section on the interconnection components can be reduced, and the reliability of the interconnection components of the entire assembly can be improved.

[0048] In some embodiments, referring to Figures 1 to 3 , a first electrode pad column is an axisymmetric figure, and the direction where the axis of symmetry is located is parallel to the second direction. Then, in the first direction, the distances from the currents or carriers at each position to the first electrode pads 13 in the first electrode pad column are approximately equal, the transmission loss is small, and the collection effect on the currents or carriers at each position is relatively balanced.

[0049] The second electrode pad column is an axisymmetric figure, and the direction where the axis of symmetry is located is parallel to the second direction. Similarly, the transmission loss is small, and the collection effect on the currents or carriers at each position is relatively balanced.

[0050] In some embodiments, referring to Figures 1 to 3 , among the multiple intermediate first electrode pads 132 in the first electrode pad column, there are included: at least one first repeating unit ( Figure 1 shown by the left blue wireframe in Figure 2 shown by the left blue wireframe and the black dashed wireframe in , and each first repeating unit is repeated at least 2 times. A first repeating unit may include: one intermediate first electrode pad 132. In one first electrode pad column, the manufacturing processes of the respective first repeating units may be compatible, and the production cost is relatively low. For example, Figure 1 , among the intermediate first electrode pads 132 in the leftmost first electrode pad column, there are included: 11 repeating and continuously distributed first repeating units a, and the areas of the respective first repeating units a are the same. For another example, Figure 2 , among the intermediate first electrode pads 132 in the leftmost first electrode pad column, there are included: the first repeating unit b in the blue frame, the first repeating unit c in the black frame, and the first repeating unit d.

[0051] In some embodiments, referring to Figures 1 to 3 , among the multiple intermediate second electrode pads 142 in the second electrode pad column, there are included: at least one second repeating unit ( Figure 1 shown by the middle blue wireframe in Figure 2 shown by the upper and lower two middle blue wireframes and the black dashed wireframe in , and each second repeating unit is repeated at least 2 times. Each second repeating unit may include: one intermediate second electrode pad 142. In one second electrode pad column, the manufacturing processes of the respective second repeating units may be compatible, and the production cost is relatively low.

[0052] For example, Figure 1 , among the intermediate second electrode pads 142 in the middle second electrode pad column, there are included: 10 repeating and continuously distributed second repeating units E ( Figure 1 shown by the middle blue wireframe in , and the 10 second repeating units E are 10 intermediate second electrode pads 142. For another example, Figure 2 , among the intermediate second electrode pads 142 in the second electrode pad column located in the middle part, there are included: 3 second repeating units ( Figure 2 shown by the upper and lower two middle blue wireframes and the middle black dashed wireframe in , wherein, the second repeating unit F in the blue wireframe is repeated 4 times; the second repeating unit G and the second repeating unit H in the black wireframe are each repeated 3 times.

[0053] In some embodiments, the area of one second repeating electrical unit is greater than the area of one first repeating electrical unit, which can enhance the welding tensile force of the second electrode pad and reduce the bonding force difference between different doping regions.

[0054] In some embodiments, the ratio of the length to the width of an electrode pad is between 3 and 8. At this time, the length of the electrode pad is relatively large, and the entire width range of the interconnecting member can be fixed. At the same time, the width of the electrode pad is not too small relative to the length, and the interconnecting member can be fixed as large as possible in terms of length.

[0055] For example, the ratio of the length to the width of an electrode pad can be: 3, 3.2, 3.5, 3.8, 4, 4.1, 4.5, 4.8, 5, 5.2, 5.5, 5.9, 6, 6.3, 6.5, 6.9, 7, 7.2, 7.5, 7.8, 8.

[0056] Figure 4 is Figure 3 The partial enlarged schematic diagram of the part outlined by the black dotted box in the figure. The photovoltaic module further includes an interconnecting member connecting adjacent back-contact solar cells. The interconnecting member is fixed to the previous cell body through the first electrode pad, and the interconnecting member is fixed to the next cell body through the second electrode pad. In some embodiments, Figures 2 to 4 , the first electrode pad 13 and the second electrode pad 14 include: a main connection section and auxiliary connection sections located at both ends of the main connection section. Among them, the width of the auxiliary connection section is smaller than the width of the main connection section, and the direction where the width is located is parallel to the second direction L2. The length of the main connection section is 0.9 - 1.1 times the width of the interconnecting member, and the length of one auxiliary connection section is 0.4 - 0.6 times the width of the interconnecting member. This design is more conducive to reducing current loss compared to rectangles and squares. For example, the shapes of the middle second electrode pad 142 and the middle first electrode pad 132 include: spindle shapes.

[0057] For example, the length of the main connection section is 0.9 times, 0.92 times, 0.93 times, 0.95 times, 0.96 times, 0.97 times, 0.99 times, 1 time, 1.02 times, 1.05 times, 1.08 times, 1.09 times, 1.1 times the width of the interconnecting member, and the length of one auxiliary connection section is 0.4 times, 0.42 times, 0.45 times, 0.46 times, 0.48 times, 0.49 times, 0.5 times, 0.52 times, 0.53 times, 0.55 times, 0.57 times, 0.58 times, 0.59 times, 0.6 times the width of the interconnecting member.

[0058] For example, the length of the main connection section of an electrode pad can be about 0.9 mm, and the length is parallel to the first direction L1. Refer to Figure 4, in the first direction L1, the middle first electrode disk 132 is narrow at both ends and wide in the middle, and is generally oval in shape. Among them, the length of the main body connection section with a wide middle can be about 0.6 mm, and the length of the narrow auxiliary connection sections at both ends can be about 0.15 mm. Therefore, the length of the middle first electrode disk 132 is about 0.9 mm. Here, the size of the spindle-shaped middle second electrode disk 142 can be the same as this, or slightly larger, and no specific limitation is made on this.

[0059] In some embodiments, referring to Figures 2 to 4 , on an N-type gate line, there are two first electrode disks with the same material and different areas, and on a P-type gate line, there are two second electrode disks with the same material and different areas, which is beneficial to designing P-type and N-type doping regions with relatively balanced areas.

[0060] In some embodiments, referring to Figures 2 to 4 , on an N-type gate line, two first electrode disks with the same material and different areas are arranged adjacent to each other. Referring to Figures 2 to 4 , on a P-type gate line, two second electrode disks with the same material and different areas are arranged adjacent to each other. Designed in this way, as Figure 5 shown, it is beneficial to design P-type and N-type doping regions with relatively balanced areas.

[0061] In some embodiments, along the second direction L2, the battery body includes multiple regions. In the same region of the battery body, along the first direction L1, the total area of the electrode disks in the first electrode disk row at the head and the total area of the electrode disks in the last electrode disk row are both greater than the total area of the electrode disks in the middle electrode disk rows. Here, the first electrode disk row at the head and the last electrode disk row are opposite in the first direction. In the first direction L1, the first electrode disk row at the head and the last electrode disk row, due to being in positions close to the edge, have relatively high requirements for welding reliability. Therefore, the area of the first and last electrode disk rows can be increased to meet the welding quality requirements.

[0062] In some embodiments, the first electrode disk and the second electrode disk are made of the same material, which is convenient for synchronously printing electrode disks of different polarities and improves the process efficiency.

[0063] In some embodiments, the first electrode pad 13 overlaps with the N-type gate line 11, and along the second direction L2, the width ratio of two portions of a first electrode pad 13 on both sides of the N-type gate line 11 is X; the second electrode pad 14 overlaps with the P-type gate line 12, and along the second direction L2, the width ratio of two portions of a second electrode pad 14 on both sides of the P-type gate line 12 is Y; X is not equal to Y. That is, along the second direction L2, the first electrode pad 13 is divided into upper and lower portions by the N-type gate line 11, and along the second direction L2, the second electrode pad 14 is divided into upper and lower portions by the P-type gate line 12, and the division ratios of the two pairs of upper and lower portions are different, which is beneficial to the insulation between electrode pads of different polarities. The magnitude relationship between X and Y here can be that X is greater than Y, or Y is greater than X. The determination of X here can be the ratio of the dimension along the second direction L2 of the upper portion located above the N-type gate line 11 to the dimension along the second direction L2 of the lower portion located below the N-type gate line 11 on the surface of a first electrode pad 13 close to the battery body. The determination of Y is the same as this, and for the sake of avoiding repetition, it will not be elaborated.

[0064] In a photovoltaic module, on an interconnector, the total area of the first electrode pads fixed thereto is smaller than the total area of the second electrode pads fixed thereto. For one interconnector, the total area of the first electrode pads fixed thereto is smaller than the total area of the second electrode pads fixed thereto. By increasing the total area of the second electrode pads fixed thereto, the bonding force between the interconnector and the second electrode pads is increased, so that the bonding forces between the interconnector and the first and second electrode pads are more balanced, and the reliability of the interconnector is improved.

[0065] On an interconnector, the height of a first electrode pad fixed thereto is smaller than the height of a second electrode pad fixed thereto. Furthermore, on an interconnector, the top surface of a first electrode pad fixed thereto is lower than the top surface of a second electrode pad fixed thereto. The top surface of the electrode pad refers to the surface of the electrode pad facing away from the battery body. For one interconnector, the second electrode pad fixed thereto has a higher height and a higher top surface. Under the action of the same magnitude of pressure acting on the interconnector, the distance between the top surface of the second electrode pad fixed thereto and the interconnector is closer, and the two are pressed more firmly, thereby increasing the bonding area between the two, increasing the bonding force between the interconnector and the second electrode pad, making the bonding between the two firm, and there is basically no risk of pulling off, and the electrical connection is more reliable.

[0066] In some embodiments, the photovoltaic module further includes a plurality of cell strings, each cell string including a plurality of back-contact solar cells connected in series; the total area of the second electrode plates in the second electrode plate column of the back-contact solar cell A1 in cell string A is greater than the total area of the first electrode plates in the first electrode plate column of the back-contact solar cell B1 in cell string B. For the second electrode plate columns of different cell strings of the photovoltaic module, the total area is still greater than that of the first electrode plate column, so as to ensure that the overall second electrode plate column in the module is greater than the first electrode plate column, which can improve the series connection reliability of the entire module.

[0067] In some embodiments, the material of the first electrode plate 13 includes a first high-temperature silver paste; the material of the second electrode plate 14 includes a second high-temperature silver paste; the bonding force between the second high-temperature silver paste and the interconnecting member is greater than the bonding force between the first high-temperature silver paste and the interconnecting member. The second high-temperature silver paste with a greater bonding force with the interconnecting member also enhances the bonding tensile force between the second electrode plate and the interconnecting member, such as the welding tensile force, making the connection between the two firm and basically having no risk of pulling off, and the electrical connection is more reliable. For example, the second high-temperature silver paste of the second electrode plate 14 contains a greater mass ratio of glass powder, etc. to improve its bonding force, and no specific limitation is made thereto.

[0068] In some embodiments, the surfaces of the battery body covered by the first electrode plate and the second electrode plate are both smooth surfaces or polished surfaces, so that the preparation processes of the surfaces of the battery body covered by the first electrode plate and the second electrode plate can be compatible, which can save costs.

[0069] In some embodiments, the overlapping area of the P-type grid line and the second electrode plate is greater than or equal to the overlapping area of the N-type grid line and the first electrode plate. The overlapping area of the P-type grid line and the second electrode plate is larger, and the area of the electrical connection between the P-type grid line and the second electrode plate is larger, which enhances the bonding force between the P-type grid line and the second electrode plate, and indirectly enhances the bonding tensile force between the P-type grid line and the interconnecting member, making the connection between the two firm and basically having no risk of pulling off, and the electrical connection is more reliable.

[0070] Refer to Figure 5 and Figure 6 , the battery body includes: an N-type doped region 15 and a P-type doped region 16, the N-type grid line 11 and the first electrode plate 13 are disposed on the N-type doped region, and the P-type grid line 12 and the second electrode plate 14 are both disposed on the P-type doped region.

[0071] The position of the N-type doped region is roughly adapted to the positions of the N-type grid line 11 and the first electrode plate 13, and the shape of the N-type doped region is roughly adapted to the shapes of the N-type grid line 11 and the first electrode plate. The position of the P-type doped region is roughly adapted to the positions of the P-type grid line 12 and the second electrode plate 14, and the shape of the P-type doped region is roughly adapted to the shapes of the P-type grid line 12 and the second electrode plate 14. As Figure 5As shown, the P-type doped region and the N-type doped region can be designed with unequal widths. Both the P-type doped region and the N-type doped region of the cell body have a first width and a second width, where the first width is greater than the second width. The first width can be correspondingly designed for the electrode pad, and the second width can be correspondingly designed for the grid lines. The grid lines can include the aforementioned N-type grid lines and P-type grid lines, thereby reserving a larger position for the design of the electrode pad. The materials of the N-type doped region and the P-type doped region here are not specifically limited. For example, they can contain at least one of doped polysilicon, doped amorphous silicon, and doped microcrystalline silicon.

[0072] Referring to Figure 6 , the back-contact solar cell may further include an interface dielectric layer 17. The interface dielectric layer 17 can be a tunneling oxide layer or the like, which is not specifically limited. An isolation region 18 is also provided between the adjacent N-type doped region 15 and P-type doped region 16. The isolation region 18 mainly serves to achieve an electrical isolation effect to avoid short circuits. The cell body may further include a substrate 19. The substrate 19 can be a silicon substrate. In some embodiments, the substrate 19 can include an N-type doped substrate, which has advantages such as a high minority carrier lifetime, no light decay, and good low-light performance. In the first direction L1, the width of one P-type doped region 16 can be about 420 μm, the width of one N-type doped region 15 can be about 250 μm, the width of one isolation region 18 can be about 240 μm, the line width of the N-type grid line 11 can be about 25 μm, and the line width of the P-type grid line 12 can be about 35 μm.

[0073] In this application, the electrode structure may not contain bus grid lines, or may contain very few bus grid lines, or may contain a relatively large number of bus grid lines, which is not specifically limited. The first electrode pad 13 can be a part of the N-type grid line 11 or be separately provided. When the first electrode pad 13 is a part of the N-type grid line 11, the width of the first electrode pad 13 is greater than the line width of the remaining part of the N-type grid line 11. The second electrode pad 14 can be a part of the P-type grid line 12 or be separately provided. When the second electrode pad 14 is a part of the P-type grid line 12, the width of the second electrode pad 14 is greater than the line width of the remaining part of the P-type grid line 12.

[0074] Figure 7The figure shows a partial structural schematic diagram of a photovoltaic module according to the present application. The photovoltaic module includes: an interconnecting member 22 and any one of the foregoing back-contact solar cells. The interconnecting member 22 electrically connects each first electrode plate 13 in the first electrode plate row of one back-contact solar cell and each second electrode plate 14 in the second electrode plate row of another adjacent back-contact solar cell. Here, the interconnecting member 22 can play a role of conductive interconnection. For example, the interconnecting member 22 can be a solder strip or a conductive backplane, etc., and no specific limitation is imposed on the interconnecting member. Here, it can be a direct electrical connection or an indirect electrical connection between the interconnecting member and the foregoing electrode, and no limitation is imposed on this.

[0075] In some embodiments, referring to Figure 7 , the interconnecting member 22 includes: a first portion 221 disposed on the first electrode plate row and a second portion 222 disposed on the second electrode plate row; the width of the second portion 222 is greater than the width of the first portion 221. Here, mainly by widening the width of the second portion 222 disposed on the second electrode plate row, the bonding area between the second electrode plate row and the interconnecting member is further increased, thereby enhancing the bonding force between the second electrode plate row and the interconnecting member, making the bonding between the two firm, and there is basically no risk of pulling off, and the electrical connection is more reliable. It should be noted that the direction in which the width of the second portion 222 is located and the direction in which the width of the first portion 221 is located are both parallel to the first direction L1.

[0076] In some embodiments, the width of the electrode plate in the second direction L2 is less than the width of the interconnecting member 22 in the first direction L1. Specifically, it means that the width of the first electrode plate 13 and the width of the second electrode plate 14 in the second direction L2 are both less than the width of the interconnecting member 22 in the first direction L1. This is beneficial to realizing the multi-point design of the electrode plate, so that direct electrical transmission between the grid line and the interconnecting member can be achieved.

[0077] In some embodiments, the length of the electrode plate in the first direction L1 is 1 to 2 times the width of the interconnecting member 22 in the first direction L1. Specifically, it means that the length of the first electrode plate 13 and the length of the second electrode plate 14 in the first direction L1 can both be 1 to 2 times the width of the interconnecting member 22 in the first direction L1, and the full fixation in the width direction of the interconnecting member can be achieved.

[0078] For example, the length of the electrode plate in the first direction L1 is 1 time, 1.1 times, 1.2 times, 1.25 times, 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.65 times, 1.7 times, 1.8 times, 1.9 times, 2 times the width of the interconnecting member 22 in the first direction L1.

[0079] It should be noted that, at the intersection of the interconnection element and the heterogeneous gate line, the heterogeneous gate line can be interrupted or continuous (without interruption), and an insulating element 23 is provided between the heterogeneous gate line and the interconnection element.

[0080] The present application also provides a photovoltaic system, which includes: a plurality of any of the above-mentioned photovoltaic modules. In the photovoltaic system, the photovoltaic modules can be distributed in an array, and the photovoltaic system can be set on a building or in a wild environment, which is not limited.

[0081] It should be noted that in the present application, the related points between the photovoltaic components and the photovoltaic system can be referenced to each other, and in order to avoid repetition, they will not be described again here.

[0082] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0083] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A back-contact solar cell, characterized in that, Comprising: A battery body and an electrode structure located on the back side of the battery body; The electrode structure includes: an N-type grid line, a P-type grid line, a first electrode disk array, and a second electrode disk array; The N-type grid line and the P-type grid line extend along a first direction and are alternately distributed along a second direction; the first direction is different from the second direction; Both the first electrode disk array and the second electrode disk array extend along the second direction and are alternately distributed along the first direction; the first electrode disk array includes: a plurality of first electrode disks arranged in columns along the second direction, and the first electrode disks are electrically connected to the N-type grid line;; the second electrode disk array includes: a plurality of second electrode disks arranged in columns along the second direction, and the second electrode disks are electrically connected to the P-type grid line; Along the second direction, the battery body includes multiple regions, and in the same region, the area of the second electrode disk is larger than the area of the first electrode disk.

2. The back-contact solar cell according to claim 1, characterized in that, The total area of the second electrode disks in the second electrode disk array is larger than the total area of the first electrode disks in the first electrode disk array.

3. The back-contact solar cell according to claim 1, wherein In the second direction, the battery body includes: two edge regions distributed relatively, and an intermediate region located between the two edge regions; In the edge region, the total area of the second electrode disks in one second electrode disk array is larger than the total area of the first electrode disks in one first electrode disk array; And / or, in the intermediate region, the total area of the second electrode disks in one second electrode disk array is larger than the total area of the first electrode disks in one first electrode disk array.

4. The back-contact solar cell according to claim 3, wherein The battery body further includes: a transition region located between the edge region and the intermediate region; In the transition region: the total area of the second electrode disks in one second electrode disk array is larger than the total area of the first electrode disks in one first electrode disk array.

5. The back contact solar cell according to claim 1, characterized in that, In the same region of the battery body, along the first direction, the total area of the electrode disks in the first electrode disk array at the head and the total area of the electrode disks in the first electrode disk array at the tail are both larger than the total area of the electrode disks in the intermediate electrode disk arrays.

6. The back-contact solar cell according to claim 1, wherein On one N-type grid line, there are two first electrode disks with the same material and different areas; On one P-type grid line, there are two second electrode disks with the same material and different areas.

7. The back-contact solar cell according to claim 1, wherein, The first electrode disk and the second electrode disk have the same material; and / or, The first electrode disk overlaps with the N-type grid line, and the width ratio of the two parts of one first electrode disk on both sides of the N-type grid line is X; the second electrode disk overlaps with the P-type grid line, and the width ratio of the two parts of one second electrode disk on both sides of the P-type grid line is Y; X is not equal to Y.

8. The back contact solar cell according to claim 3, characterized in that, In the edge region, the ratio of the length to the width of the second electrode disk is C; in the intermediate region, the ratio of the length to the width of the second electrode disk is D; The number of second electrode disks located in the intermediate region is more than 9 times the number of second electrode disks located in the edge region, and D is greater than 3C.

9. The back contact solar cell according to any one of claims 1 to 8, characterized in that The battery body includes an N-type doped substrate, and / or, the surfaces of the battery body covered by the first electrode disk and the second electrode disk are both smooth surfaces; And / or, both the P-type doped region and the N-type doped region of the battery body have a first width and a second width, and the first width is greater than the second width.

10. The back contact solar cell according to any one of claims 1 to 8, characterized in that, The overlapping area of the P-type gate line and the second electrode pad is greater than the overlapping area of the N-type gate line and the first electrode pad.

11. A photovoltaic module, characterized in that, Comprising: A plurality of back-contact solar cells according to any one of claims 1 to 10, and an interconnect for connecting adjacent back-contact solar cells, the interconnect being fixed to the previous battery body through the first electrode pad, and the interconnect being fixed to the subsequent battery body through the second electrode pad; On an interconnect, the total area of the first electrode pads fixed thereto is smaller than the total area of the second electrode pads fixed thereto.

12. The photovoltaic module according to claim 11, characterized in that, The photovoltaic module includes a plurality of cell strings, and the cell strings include a plurality of back-contact solar cells connected in series; the total area of the second electrode pads in the second electrode pad column of the back-contact solar cell A1 in the cell string A is greater than the total area of the first electrode pads in the first electrode pad column of the back-contact solar cell B1 in the cell string B.

13. The photovoltaic module according to claim 11, characterized in that, The ratio of the length to the width of an electrode pad is between 3 and 8; and / or, The electrode pad includes a main connection section and auxiliary connection sections located at both ends of the main connection section; the length of the main connection section is 0.9 to 1.1 times the width of the interconnect, and the length of one of the auxiliary connection sections is 0.4 to 0.6 times the width of the interconnect; the width of the auxiliary connection section is smaller than the width of the main connection section.

14. A photovoltaic system, comprising: A photovoltaic module according to any one of claims 11 to 13.

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