A back contact cell, back contact laminate cell and photovoltaic module

Abstract

The application relates to a back contact battery, a back contact laminated battery and a photovoltaic module. The back contact battery comprises a battery piece, the back surface of the battery piece is provided with an insulating part and a pad, the insulating part is located at least on two sides of the pad in a first direction, the pad is used for being connected with a solder strip, and a conductive body is arranged on the pad; the pad and the insulating parts on the two sides have a containing space, and the ratio of the volume V1 of the conductive body to the volume V2 of the containing space satisfies 0.5<=V1 / V2<=1. In the application, by limiting the volume V1 of the conductive body and the volume V2 of the containing space, the conductive body on the pad is not too much or too little, the conductive body is not easy to overflow to the outside of the pad to cause the disconnection of a fine grid, meanwhile, the conductive body can provide reliable connection for the solder strip and the pad, and the volume of the conductive body is convenient to determine.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a back-contact cell, a back-contact tandem cell, and a photovoltaic module. Background Technology

[0002] Photovoltaic modules can directly convert solar radiation energy into electrical energy, mainly based on the photovoltaic effect of crystalline silicon. When the photons of sunlight are absorbed by the semiconductor crystalline silicon, electron-hole pairs are generated. When these electron-hole pairs reach the pn junction composed of p-type and n-type crystalline silicon, they are separated to both sides of the pn junction by the junction electric field. When an external load is connected, a photocurrent is formed, and electrical energy is output.

[0003] Photovoltaic modules can be formed by connecting back-contact cells. Adjacent back-contact cells are electrically connected by solder strips. The back-contact cells have pads for connecting with the solder strips. Solder paste is applied to the pads. Too much solder paste can easily cause the grid lines on the back-contact cells to break. Too little solder paste can easily lead to poor connection strength between the solder strip and the pads, causing the solder strip to fall off the pads. Currently, there is a problem that it is difficult to determine the amount of solder paste. Utility Model Content

[0004] This application provides a back-contact cell, a back-contact tandem cell, and a photovoltaic module to solve the problem of difficulty in determining the amount of solder paste.

[0005] This application provides a back contact battery, including a battery cell. The back of the battery cell is provided with an insulating portion and a pad. The insulating portion is located at least on both sides of the pad along a first direction. The pad is used to connect with a solder strip. A conductor is provided on the pad. There is a receiving space between the pad and the insulating portion on both sides. The ratio of the volume V1 of the conductor to the volume V2 of the receiving space satisfies: 0.5≤V1 / V2≤1.

[0006] In one possible design, the ratio of the volume V1 of the conductor to the volume V2 of the accommodating space is 0.8.

[0007] In one possible design, along the third direction, the area of ​​the projection of the pad onto the cell is S; along the third direction, the distance between the insulating part and the pad is H; the volume of the accommodating space is V2 = S × H.

[0008] In one possible design, along the first direction, the distance between the two insulating portions on both sides of the pad is L1; along the second direction, the size of the pad is L2; ​​along the third direction, the distance between the insulating portion and the pad is H; and the volume of the accommodating space is V2 = L1 × L2 × H.

[0009] In one possible design, along the first direction, the distance L1 between the two insulating portions on both sides of the pad satisfies: 0.7mm ≤ L1 ≤ 3mm.

[0010] In one possible design, along the second direction, the size L2 of the pad satisfies: 0.5mm ≤ L2 ≤ 2mm.

[0011] In one possible design, the distance H between the insulating part and the pad satisfies: 0.015mm ≤ H ≤ 0.08mm.

[0012] In one possible design, the pad has a bearing surface, the conductor is disposed on the bearing surface, and along the first direction, from the edge of the bearing surface to the center of the bearing surface, at least a portion of the bearing surface gradually decreases in height along a third direction.

[0013] In one possible design, along a second direction, from the edge of the bearing surface toward the center of the bearing surface, at least a portion of the bearing surface gradually decreases in height along a third direction.

[0014] This application provides a back-contact stacked battery, including a back-contact bottom battery and a perovskite top battery. The perovskite top battery is electrically connected to the front side of the back-contact bottom battery, and the back-contact bottom battery is the back-contact battery described above.

[0015] This application provides a photovoltaic module, including the back-contact cell or the back-contact stacked cell described above.

[0016] In this application, a conductor is provided on the pad, which is generally solder paste. When the solder ribbon is soldered onto the pad, the solder paste melts when heated to form a metal alloy solder joint. On the one hand, the metal alloy solder joint establishes an electrical connection between the solder ribbon and the pad. On the other hand, the metal alloy solder joint provides a reliable connection between the pad and the solder ribbon, making it difficult for the solder ribbon to detach from the pad.

[0017] The number of conductors on the pads should be neither too many nor too few. If there are too many conductors on the pads, when the solder ribbon is soldered onto the pads, the solder ribbon will contact the conductors, compressing them. This causes the conductors to decrease in size along the thickness direction of the cell (Z-direction) and increase in size along the perpendicular Z-direction. In other words, the conductors are prone to overflowing from the pads and contacting the first or second grid. Alternatively, if the solder ribbon deviates from the preset placement position, it can easily carry the conductors onto the first or second grid. Due to the significant temperature changes of the cell during soldering, the conductors undergo thermal expansion and contraction, which can easily cause the first or second grid that is in contact with them to break. The collection of photogenerated current by the first or second fine grid affects the photoelectric conversion efficiency of the back contact cell. If there is too little conductivity on the pad, the size of the metal alloy solder joint formed between the solder ribbon and the pad after heating will be small when the solder ribbon is soldered to the pad. This results in a large resistance at the connection between the solder ribbon and the pad, and a large loss of photogenerated current during the process of being led to the cell. In addition, the metal alloy solder joint cannot provide a reliable connection between the solder ribbon and the pad, making it easy for the solder ribbon to fall off the pad. As a result, the current collected by the first or second fine grid at the point where the solder ribbon falls off cannot be led out, thus affecting the photoelectric conversion efficiency of the back contact cell.

[0018] Therefore, the amount of conductor on the pad should be set within a reasonable range, that is, the ratio of the volume of the conductor V1 to the volume of the accommodating space V2 should satisfy: 0.5≤V1 / V2≤1, so that the conductor is not likely to overflow outside the pad and cause the first or second fine gate to break, while providing a reliable connection between the solder strip and the pad, and making it easy to determine the size of the conductor.

[0019] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0020] Figure 1 This is a partial structural diagram of the back contact battery provided in this application in a specific embodiment;

[0021] Figure 2 for Figure 1 A partial cross-sectional view of the back contact battery in one embodiment;

[0022] Figure 3 for Figure 1 A partial cross-sectional view of the back contact battery in another embodiment;

[0023] Figure 4 for Figure 3 A schematic diagram of the structure of the pads in the diagram;

[0024] Figure 5 for Figure 1 A cross-sectional view of the back contact battery in another embodiment;

[0025] Figure 6 This is a partial structural schematic diagram of a specific embodiment of the back-contact stacked battery provided in this application;

[0026] Figure 7 This is a schematic diagram of the structure of the photovoltaic module provided in this application, wherein the cell string is composed of back-contact cells;

[0027] Figure 8 This is a schematic diagram of the structure of the photovoltaic module provided in this application, wherein the battery string consists of... Figure 6 It consists of back-contact stacked cells.

[0028] Figure label:

[0029] 1- Battery string;

[0030] 10-cell battery;

[0031] 10A top battery;

[0032] 10b-bottom battery;

[0033] 11-First fine grid;

[0034] 12-Second fine grid;

[0035] 13-Insulation part;

[0036] 14 - Pads;

[0037] 141 - Bearing surface;

[0038] 142-groove;

[0039] 15- Conductor;

[0040] 2-Welding strip;

[0041] 3-Front-side packaging structure;

[0042] 4-Front-side film layer;

[0043] 5-Backside film layer;

[0044] 6- Rear packaging structure.

[0045] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. Detailed Implementation

[0046] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0047] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0048] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0049] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0050] It should be noted that the directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when it is mentioned that an element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.

[0051] This application provides a back contact battery, which can be one of the following: interdigitated back contact (IBC), heterojunction back contact (HBC), or tunnel oxide back contact (TBC).

[0052] For an IBC cell, along its thickness direction, it sequentially includes a silicon nitride inversion layer, an N+ front surface field, an N-type substrate silicon layer, a P+ emitter, an N+ back field, an aluminum oxide passivation layer, a silicon nitride antireflection layer, and a silver electrode. IBC cells utilize ion implantation technology to obtain P- and N-regions with good uniformity and precisely controllable junction depth. The absence of grid lines on the front side eliminates light-blocking current loss from the metal electrodes, maximizing the utilization of incident photons and improving short-circuit current by approximately 7% compared to conventional solar cells. Due to its back-contact structure, grid line shading is not a concern, allowing for a wider grid line ratio, thus reducing series resistance and achieving a high fill factor. Optimized design of surface passivation and light-trapping structures can be achieved, resulting in lower front surface recombination rates and surface reflection.

[0053] HBC cells effectively combine the advantages of IBC and heterojunction cells. Their front surface passivation layer uses hydrogenated amorphous silicon, while N-type and P-type amorphous silicon films are deposited on the back side to form a heterojunction. HBC cells fully utilize the superior surface passivation properties of amorphous silicon, and the heterojunction structure formed on the back side exhibits excellent passivation, enabling the simultaneous achievement of higher short-circuit current and open-circuit voltage, thereby improving photoelectric conversion efficiency.

[0054] For TBC cells, the advantages of both Topcon's tunneling oxide layer technology and IBC back-side electrode arrangement are combined, resulting in significantly improved passivation and open-circuit voltage, achieving higher cell conversion efficiency while maintaining economic viability. The complete TBC cell production process mainly includes depositing the tunneling oxide layer and P+ polycrystalline silicon, depositing the passivation film, and printing electrodes on the back of the silicon wafer. Building upon the TOPCon production process, TBC cells require additional back-side electrode processes such as masking, laser grooving, PN region fabrication, and etching. Masking is primarily performed using APCVD or PECVD, PN region fabrication is mainly done using PECVD, etching primarily employs traditional wet processing equipment, and grooving is performed using laser equipment.

[0055] Specifically, the back-contact battery includes a battery cell 10, which has a front side and a back side. The front side of the battery cell 10 refers to the light-receiving surface, and the back side refers to the light-receiving surface. For example... Figure 1 As shown, the back of the solar cell 10 is provided with a first fine grid 11 and a second fine grid 12 of different polarities. One of the first fine grids 11 and the other fine grid 12 is a positive electrode grid, and the other is a negative electrode grid. Both the first fine grid 11 and the second fine grid 12 extend along a first direction X, and are arranged intersecting and spaced apart along a second direction Y. The first direction X intersects the second direction Y to collect the photocurrent generated by the solar cell. (See attached instruction manual) Figure 1The red line in the diagram shows the first fine grid 11, and the blue line shows the second fine grid 12.

[0056] In one embodiment, the back of the solar cell 10 is provided with a first main grid and a second main grid with different polarities. The polarity of the first main grid is the same as that of the first fine grid 11, and the polarity of the second main grid is the same as that of the second fine grid 12. Both the first and second main grids extend along a second direction Y, and are spaced apart and staggered along a first direction X, such that the first main grid is connected to the first fine grid 11 to collect the photocurrent collected by the first fine grid 11, and the second main grid is connected to the second fine grid to collect the photocurrent collected by the second fine grid 12. At the same time, the second fine grid 12 is disconnected at the first main grid to avoid short circuit due to contact between the second fine grid 12 and the first fine grid 11, and the first fine grid 11 is disconnected at the second main grid to avoid short circuit due to contact between the first fine grid 11 and the second main grid. A first pad is provided on the first main gate, and a first solder strip is connected to the first main gate through the first pad. A second pad is provided on the second main gate, and a second solder strip is connected to the second main gate through the second pad. That is, the first solder strip and the second solder strip also extend along the second direction Y to conduct the current collected by the first main gate and the second main gate. It can be understood that the first pad and the second pad can be located at the position in contact with the fine gate (i.e., the first fine gate 11 and the second fine gate 12), or they can be located between two adjacent fine gates.

[0057] In another embodiment, the back of the solar cell 10 does not have a first main grid and a second main grid. A first solder strip extending along the second direction Y is directly connected to the first fine grid 11 to collect and discharge the photocurrent collected by the first fine grid 11. A second solder strip extending along the second direction Y is directly connected to the second fine grid 12 to collect and discharge the photocurrent collected by the second fine grid 12. Similarly, the second fine grid 12 is disconnected at the first solder strip to avoid short circuit due to contact between the second fine grid 12 and the first solder strip, and the first fine grid 11 is disconnected at the second solder strip to avoid short circuit due to contact between the first fine grid 11 and the second solder strip. A first pad is provided at the connection between the first fine grid 11 and the first solder strip to ensure reliable connection between the first fine grid 11 and the first solder strip, and a second pad is provided at the connection between the second fine grid 12 and the second solder strip to ensure reliable connection between the second fine grid 12 and the second solder strip.

[0058] Specifically, a first insulating portion is provided at the end of the first fine gate 11 that is disconnected at the second solder strip. The first insulating portion is located at least on both sides of the second solder pad, thereby further preventing the first fine gate 11 from contacting the second solder strip and short-circuiting. A second insulating portion is provided on the outer periphery of the portion of the second fine gate 12 that is disconnected at the first solder strip. The second insulating portion is located at least on both sides of the first solder pad, thereby further preventing the second fine gate 12 from contacting the first solder strip and short-circuiting.

[0059] In both embodiments described above, since the first pad and the second pad have the same structure, the first solder strip and the second solder strip have the same structure, and the first insulating portion and the second insulating portion have the same structure, for ease of description, the first pad and the second pad are collectively referred to as pad 14, the first solder strip and the second solder strip are collectively referred to as solder strip 2, and the first insulating portion and the second insulating portion are collectively referred to as insulating portion 13. The insulating portion 13 can cover the end of the second fine gate 12 or can be disposed around the end of the second fine gate 12, as long as it can prevent short circuits between fine gates of different polarities and the main gate, or between fine gates of different polarities.

[0060] A conductor 15 is provided on the pad 14. The conductor 15 is generally solder paste. When the solder ribbon 2 is soldered onto the pad 14, the solder paste melts when heated to form a metal alloy solder joint. On the one hand, the metal alloy solder joint establishes an electrical connection between the solder ribbon 2 and the pad 14. On the other hand, the metal alloy solder joint provides a reliable connection between the pad 14 and the solder ribbon 2, making it difficult for the solder ribbon 2 to detach from the pad 14.

[0061] There is a space between the pad 14 and the insulating portions 13 on both sides, and the ratio of the volume V1 of the conductor 15 to the volume V2 of the space satisfies: 0.5 ≤ V1 / V2 ≤ 1. For example, the ratio of the volume V1 of the conductor 15 to the volume V2 of the space can be: 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.58, 0.59, 0.6, 0.62, 0.64, 0.65, 0.68, 0.69, 0.7, 0.72, 0.74, 0.75, 0.78, 0.79, 0.8, 0.82, 0.84, 0.85, 0.88, 0.89, 0.9, 0.92, 0.94, 0.95, 0.97, 0.99, 1, etc.

[0062] The number of conductors 15 on the pad 14 should not be too many or too few. If there are too many conductors 15 on the pad 14 (e.g., V1 / V2 is greater than 1), when the solder ribbon 2 is soldered onto the pad 14, the solder ribbon 2 will contact the conductors 15, compressing them. This will cause the conductors 15 to decrease in size along the thickness direction (third direction Z) of the cell 10 and increase in size along the perpendicular third direction Z. In other words, the conductors 15 are likely to overflow from the pad 14 and contact the first fine grid 11 or the second fine grid 12. Alternatively, if the solder ribbon 2 deviates from the preset placement position, it may carry the conductors 15 onto the first fine grid 11 or the second fine grid 12. Due to the large temperature change of the cell 10 during soldering, the conductors 15 will expand and contract, easily causing the first fine grid 11 or the second fine grid 12 in contact with them to expand and contract. If a grid break occurs, it will affect the collection of photocurrent by the first fine grid 11 or the second fine grid 12, thereby affecting the photoelectric conversion efficiency of the back contact cell. If there are too few conductors 15 on the pad 14 (e.g., V1 / V2 is less than 0.5), when the solder ribbon 2 is soldered to the pad 14, the size of the metal alloy solder joint formed between the solder ribbon 2 and the pad 14 after heating will be small. This will result in a large resistance at the connection between the solder ribbon 2 and the pad 14, and a large loss of photocurrent during the process of being led to the cell 10. Furthermore, the metal alloy solder joint cannot provide a reliable connection between the solder ribbon 2 and the pad 14, making it easy for the solder ribbon 2 to fall off the pad 14. As a result, the current collected by the first fine grid 11 or the second fine grid 12 at the point where the solder ribbon 2 falls off cannot be led out, thus affecting the photoelectric conversion efficiency of the back contact cell.

[0063] Therefore, the amount of conductor 15 on pad 14 should be set within a reasonable range so that the conductor 15 does not easily overflow outside the pad 14 and cause the first fine gate 11 or the second fine gate 12 to break, while providing a reliable connection between the solder ribbon 2 and the pad 14. In addition, by comparing the volume V1 of the conductor 15 with the volume V2 of the accommodating space, it is easy to determine the amount of conductor 15.

[0064] Furthermore, such as Figure 1 As shown, there is a gap between the pad 14 and the insulating portion 13 along the first direction X. When the pad 14 is located between adjacent fine gates and the conductor 15 is pressed by the solder strip 2 and overflows outside the pad 14, the gap between the pad 14 and the insulating portion 13 can prevent the conductor 15 from contacting the first fine gate 11 or the second fine gate 12 surrounded by the insulating portion 13 to a certain extent, thereby preventing the conductor 15 overflowing outside the pad 14 from causing the first fine gate 11 or the second fine gate 12 to break.

[0065] In addition, the insulating portion 13 located on both sides of the pad 14 along the first direction X can also prevent the conductor 15 from contacting the first fine gate 11 or the second fine gate 12 surrounded by the insulating portion 13 to a certain extent, thereby preventing the conductor 15 overflowing outside the pad 14 from causing the first fine gate 11 or the second fine gate 12 to break.

[0066] It is understandable that the amount of conductor 15 on pad 14 is relative to the size of the space between pad 14 and the insulating portions 13 on both sides.

[0067] In one embodiment, such as Figure 2 As shown, along the third direction Z, the area of ​​the projection of the pad 14 onto the cell 10 is S; along the third direction Z, the distance between the insulating part 13 and the pad 14 is H, and the volume of the accommodating space is V2 = S × H.

[0068] The accommodating space is defined by the area S of the projection of the pad 14 onto the cell 10 and the distance H between the insulating part 13 and the pad 14. That is, the accommodating space is the space above the pad 14 that is lower than the height of the insulating part 13, so that the ratio of the volume V1 of the conductor 15 to the volume V2 of the accommodating space can more intuitively reflect the amount of the conductor 15.

[0069] Specifically, when the volume V1 of the conductor 15 on the pad 14 is equal to the volume V2 of the accommodating space (i.e., V1 / V2 = 1), the conductor 15 can just fill the space above the pad 14 that is lower than the height of the insulating portion 13. When the solder ribbon 2 is soldered onto the pad 14, the solder ribbon 2 presses down on the conductor 15, causing the dimension of the conductor 15 to decrease along the third direction Z and increase along the perpendicular third direction Z. At this time, the conductor 15 will overflow outside the pad 14. However, due to the gap between the pad 14 and the insulating portion 13 and the insulating portion 13 itself, the conductor 15 can further prevent the first fine gate 11 or the second fine gate 12 surrounding the insulating portion 13 from contacting the first fine gate 11 or the second fine gate 12. This prevents the conductor 15 overflowing outside the pad 14 from causing the first fine gate 11 or the second fine gate 12 to break.

[0070] When the ratio of the volume V1 of the conductor 15 on the pad 14 to the volume V2 of the accommodating space is 0.5, when the solder ribbon 2 is soldered onto the pad 14, the solder ribbon 2 presses the conductor 15, causing the dimension of the conductor 15 to decrease along the third direction Z and increase along the perpendicular third direction Z. At this time, along the third direction Z, the conductor 15 covers most of the upper surface of the pad 14, thereby providing reliable support for the solder ribbon 2 and the pad 14.

[0071] In another embodiment, such as Figure 1 and Figure 2As shown, along the first direction X, the distance between the two insulating portions 13 on both sides of the pad 14 is L1; along the second direction Y, the size of the pad 14 is L2; ​​along the third direction Z, the distance between the insulating portion 13 and the pad 14 is H, and the volume of the accommodating space is V2 = L1 × L2 × H.

[0072] That is, by defining the accommodating space by the distance L1 between the two insulating portions 13 on both sides of the pad 14 and the dimension of the pad 14 along the second direction Y, the maximum volume V1 that the conductor 15 can be set in this embodiment is greater than the maximum volume V1 that the conductor 15 can be set in the previous embodiment, so that the volume range that the conductor 15 can be set in this embodiment is larger, and the volume accuracy requirements of the conductor 15 are reduced.

[0073] Specifically, when the volume V1 of the conductor 15 on the pad 14 is equal to the volume V2 of the accommodating space (i.e., V1 / V2 = 1), and the solder ribbon 2 is not placed on the cell 10, the conductor 15 is entirely located on the pad 14. Along the third direction Z, the height of the conductor 15 is generally higher than the height of the insulating part 13. When the solder ribbon 2 is soldered onto the pad 14, the solder ribbon 2 compresses the conductor 15, causing the dimension of the conductor 15 to decrease along the third direction Z and increase along the perpendicular third direction Z. The conductor 15 will overflow outside the pad 14. At this time, the insulating part 13 itself can prevent the conductor 15 from contacting the first fine grid 11 or the second fine grid 12 surrounding the insulating part 13, so that the conductor 15 overflowing outside the pad 14 will not cause the first fine grid 11 or the second fine grid 12 to break.

[0074] Optionally, along the first direction X, the distance L1 between the two insulating portions 13 on both sides of the pad 14 satisfies: 0.7mm ≤ L1 ≤ 3mm. For example, the specific distance L1 between the two insulating portions 13 on both sides of the pad 14 can be: 0.7mm, 0.71mm, 0.72mm, 0.75mm, 0.77mm, 0.79mm, 0.8mm, 0.82mm, 0.85mm, 0.88mm, 0.9mm, 0.92mm, 0.95mm, 0.98mm, 1mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm, 1.25mm, 1.3mm, 1.35mm, 1.4mm. m, 1.45mm, 1.5mm, 1.55mm, 1.6mm, 1.65mm, 1.7mm, 1.75mm, 1.8mm, 1.85mm, 1.9mm, 1.95mm, 2mm, 2.05mm, 2.1m m, 2.15mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 2.92mm, 2.95mm, 2.98mm, 2.99mm, 3mm, etc.

[0075] Along the first direction X, the distance L1 between the two insulating portions 13 on both sides of the pad 14 should not be too large or too small. If the distance L1 between the two insulating portions 13 on both sides of the pad 14 is too large (for example, L1 is greater than 3.0 mm), the distance between the insulating portion 13 and the surrounding first fine gate 11 or second fine gate 12 will be too small. When the insulating portion 13 is printed off its preset position, the surrounding first fine gate 11 or second fine gate 12 may extend beyond the insulating portion 13, causing the insulating portion 13 to be ineffective. If the fine gate and the main gate of opposite polarity (and the solder ribbon 2 connected to the main gate of opposite polarity) are not effectively isolated, or if the fine gate and the solder ribbon 2 connected to the fine gate of opposite polarity cannot be effectively isolated, a short circuit will occur. If the distance L1 between the two insulating portions 13 on both sides of the pad 14 is too small (for example, L1 is less than 0.7 mm), the distance between the insulating portion 13 and the pad 14 will be too small. When the insulating portion 13 is printed off its preset position, the insulating portion 13 may extend onto the pad 14, affecting the connection reliability between the solder ribbon 2 and the pad 14. At the same time, a small distance between the insulating portion 13 and the first fine gate 11 or the second fine gate 12 it surrounds, and a small distance between the insulating portion 13 and the pad 14, will increase the accuracy required for printing the insulating portion 13, thus increasing the cost of printing the insulating portion 13.

[0076] Therefore, along the first direction X, the distance L1 between the two insulating portions 13 on both sides of the pad 14 should be set within a reasonable range so that the distance between the insulating portion 13 and the first fine gate 11 or the second fine gate 12 it surrounds is not too small, and the distance between the insulating portion 13 and the pad 14 is not too small.

[0077] Optionally, pad 14 can be square, rectangular, circular, oval, etc., as shown in the instruction manual. Figure 1 A pad 14 with a positive orientation and chamfered edges is shown. (Example) Figure 1 As shown, along the second direction Y, the dimension L2 of pad 14 satisfies: 0.5mm ≤ L2 ≤ 2mm. For example, the dimension L2 of pad 14 can specifically be: 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 1.95mm, 1.98mm, 2mm, etc.

[0078] Along the second direction Y, the size L2 of the pad 14 should not be too large or too small. If the size L2 of the pad 14 is too large (for example, L2 is greater than 2mm), it will increase the cost of forming the pad 14 and the production cost of the back contact battery. If the size L2 of the pad 14 is too small (for example, L2 is less than 0.5mm), the area of ​​the pad 14 used to support the conductor 15 is too small. On the one hand, the conductor 15 is easy to overflow outside the pad 14. On the other hand, the maximum connection area between the pad 14 and the solder strip 2 is small, resulting in a low connection strength between the pad 14 and the solder strip 2, and the solder strip 2 is easy to separate from the pad 14.

[0079] Therefore, along the second direction Y, the size L2 of the pad 14 should be set within a reasonable range so that the cost of forming the pad 14 is low, the conductor 15 does not easily overflow outside the pad 14, and the connection strength between the solder strip 2 and the pad 14 is high.

[0080] Optionally, the distance H between the insulating part 13 and the pad 14 satisfies: 0.015mm≤H≤0.08mm. For example, the distance H between the insulating part 13 and the pad 14 can be: 0.015mm, 0.016mm, 0.018mm, 0.019mm, 0.02mm, 0.022mm, 0.025mm, 0.028mm, 0.03mm, 0.032mm, 0.035mm, 0.038mm, 0.04mm, 0.042mm, 0.045mm, 0.048mm, 0.05mm, 0.052mm, 0.055mm, 0.058mm, 0.06mm, 0.062mm, 0.065mm, 0.068mm, 0.07mm, 0.072mm, 0.075mm, 0.078mm, 0.079mm, 0.08mm, etc.

[0081] The distance H between the insulating part 13 and the pad 14 should not be too large or too small. If the distance H between the insulating part 13 and the pad 14 is too large (for example, H is greater than 0.08 mm), the height of the insulating part 13 will be too high, which will increase the cost of forming the insulating part 13 and the production cost of the back contact battery. If the distance H between the insulating part 13 and the pad 14 is too small (for example, H is less than 0.015 mm), the insulating part 13 will have a weaker ability to prevent the conductor 15 overflowing to the pad 14 from contacting the first fine grid 11 or the second fine grid 12 surrounded by the insulating part 13, and the first fine grid 11 or the second fine grid 12 will be prone to breakage.

[0082] Therefore, the distance H between the insulating part 13 and the pad 14 should be set within a reasonable range so that the cost of forming the insulating part 13 is low while the insulating part 13 has a good ability to block the conductor 15 from overflowing to the pad 14.

[0083] Preferably, the ratio of the volume V1 of the conductor 15 to the volume V2 of the accommodating space is 0.8. On the one hand, this ensures that the amount of conductor 15 on the pad 14 is not excessive, and that the conductor 15 is not likely to overflow from the pad 14 when pressed by the solder ribbon 2. Furthermore, the cost of setting the conductor 15 is low. On the other hand, this ensures that the amount of conductor 15 on the pad 14 is not insufficient, and that the conductor 15 can provide a reliable connection between the pad 14 and the solder ribbon 2, making it less likely for the solder ribbon 2 to detach from the pad 14.

[0084] In the above embodiments, such as Figure 2 , Figure 3 and Figure 5 As shown, the pad 14 has a bearing surface 141, and the conductor 15 is disposed on the bearing surface 141.

[0085] In one implementation, such as Figure 2 As shown, the bearing surface 141 is a plane parallel to the first direction X and the second direction Y. At this time, the bearing surface 141 has the advantage of being easy to process and form.

[0086] In another implementation, such as Figure 3 and Figure 4 As shown, along the first direction X, from the edge of the bearing surface 141 to its center, at least a portion of the bearing surface 141 gradually decreases in height along the third direction Z. This allows the conductor 15 to remain at the center of the bearing surface 141 under the influence of gravity when it melts due to heat, preventing it from overflowing out of the pad 14 along the first direction X. Simultaneously, when the solder ribbon 2 is soldered onto the pad 14, it also tends to remain at the center of the bearing surface 141 under the influence of gravity, resulting in better encapsulation of the solder ribbon 2 by the conductor 15 and higher reliability of the connection between the conductor 15 and the solder ribbon 2 and the pad 14. At this time, the projection of the bearing surface 141 along the second direction Y can be arc-shaped.

[0087] Optionally, along the second direction Y, from the edge of the bearing surface 141 to the center of the bearing surface 141, the height of the bearing surface 141 remains unchanged, so as to make the contact area between the solder strip 2 and the conductor 15 larger.

[0088] Optionally, along the second direction Y, from the edge of the bearing surface 141 towards its center, the height of at least a portion of the bearing surface 141 gradually decreases, making it less likely for the conductor 15 to overflow beyond the solder pad 14 when heated and melted. The curvature of the bearing surface 141 in the first direction X is less than the curvature of the bearing surface 141 in the second direction Y, to ensure a larger contact area between the conductor 15 and the solder strip 2. It is understood that the curvature of the bearing surface 141 in the first direction X can also be equal to or greater than the curvature of the bearing surface 141 in the second direction Y.

[0089] Optionally, along the first direction X, from the edge of the bearing surface 141 towards the center of the bearing surface 141, the height of the bearing surface 141 gradually decreases; along the second direction Y, from the edge of the bearing surface 141 towards the center of the bearing surface 141, the height of the bearing surface 141 also gradually decreases; and the curvature of the bearing surface 141 in the first direction X is greater than or less than the curvature of the bearing surface 141 in the second direction Y. Preferably,

[0090] In yet another implementation, such as Figure 5 As shown, a groove 142 is provided on the pad 14, and a conductor 15 is disposed in the groove 142. The groove 142 extends along the third direction Z to the battery cell 10 and penetrates the pad 14 along the second direction Y, so that the conductor 15 is not easy to overflow out of the pad 14 along the first direction X when it is heated and melted.

[0091] This application also provides a back-contact stacked battery, such as... Figure 6 As shown, the back-contact tandem solar cell includes a back-contact bottom cell 10b and a perovskite top cell 10a. The perovskite top cell 10a is electrically connected to the front side of the back-contact bottom cell 10b, which is the back-contact cell described above. The back-contact tandem solar cell also includes an intermediate connecting layer, which connects the back-contact bottom cell 10b and the perovskite top cell 10a. The intermediate connecting layer can be selected from a transparent material with a high refractive index, such as a transparent conductive metal oxide thin film (ITO). An effective intermediate connecting layer needs to have high light transmittance to reduce light reflection and absorption at the interface of the intermediate connecting layer, and good conductivity to reduce the impact of series resistance on device performance.

[0092] This application also provides a photovoltaic module, which includes the aforementioned back-contact cells or the aforementioned back-contact stacked cells. The back-contact cells or back-contact stacked cells are connected in series via solder strips 2 to form a cell string 1. Multiple cell strings 1 are connected in parallel via busbars to form a cell string group. Multiple cell string groups are connected in series via busbars and jumpers.

[0093] like Figure 6 and Figure 7 As shown, the photovoltaic module includes: a front encapsulation structure 3, a front film layer 4, multiple cell strings, a back film layer 5, and a back encapsulation structure 6. Figure 6 This illustrates a photovoltaic module with a battery string consisting of back-contact cells. Figure 7 This illustrates a photovoltaic module whose battery string consists of back-contact stacked cells.

[0094] Among them, the front encapsulation structure 3, the front film layer 4, the back film layer 5 and the back encapsulation structure 6 encapsulate the battery string to ensure that the photovoltaic module has high mechanical strength, reduce the impact of hail, wind, mechanical vibration and other conditions on the back contact photovoltaic module, improve the sealing performance of the back contact photovoltaic module, and enhance its corrosion resistance and safety.

[0095] Specifically, the front encapsulation structure 3 and the back encapsulation structure 6 can be one of rigid materials such as tempered glass, polyethylene terephthalate (PET), and polycarbonate (PC), or one of flexible materials such as polyvinyl fluoride (PVF), ethylene-tetrafluoroethylene copolymer (ETFE), and polyvinylidene fluoride (PVDF). These materials have high light transmittance, which can improve the photoelectric conversion efficiency of the back-contact photovoltaic module and ensure its power output. The front film layer 4 and the back film layer 5 can be one of the following materials: ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), polyvinyl butyral (PVB), EVA-POE-EVA co-extruded film (EPE), EVA-POE co-extruded film (EP).

[0096] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A back-contact battery, characterized in that, The back contact battery includes a battery cell (10), and an insulating part (13) and a pad (14) are provided on the back side of the battery cell (10). The insulating part (13) is located at least on both sides of the pad (14) along the first direction (X). The pad (14) is used to connect with the solder strip (2). A conductor (15) is provided on the pad (14). There is a receiving space between the pad (14) and the insulating portions (13) on both sides, and the ratio of the volume V1 of the conductor (15) to the volume V2 of the receiving space satisfies: 0.5≤V1 / V2≤1.

2. The back contact battery according to claim 1, characterized in that, The ratio of the volume V1 of the conductor (15) to the volume V2 of the accommodating space is 0.

8.

3. The back contact battery according to claim 1, characterized in that, Along the third direction (Z), the area of ​​the projection of the pad (14) onto the battery cell (10) is S; along the third direction (Z), the distance between the insulating part (13) and the pad (14) is H; The volume of the accommodating space is V2 = S × H.

4. The back contact battery according to claim 1, characterized in that, Along the first direction (X), the distance between the two insulating portions (13) on both sides of the pad (14) is L1; along the second direction (Y), the size of the pad (14) is L2; ​​along the third direction (Z), the distance between the insulating portion (13) and the pad (14) is H; The volume of the accommodating space is V2 = L1 × L2 × H.

5. The back contact battery according to claim 4, characterized in that, Along the first direction (X), the distance L1 between the two insulating portions (13) on both sides of the pad (14) satisfies: 0.7mm≤L1≤3mm.

6. The back contact battery according to claim 4, characterized in that, Along the second direction (Y), the size L2 of the pad (14) satisfies: 0.5mm≤L2≤2mm.

7. The back contact battery according to claim 3 or 4, characterized in that, The distance H between the insulating part (13) and the pad (14) satisfies: 0.015mm≤H≤0.08mm.

8. The back contact battery according to any one of claims 1-6, characterized in that, The pad (14) has a bearing surface (141), and the conductor (15) is disposed on the bearing surface (141). Along the first direction (X), from the edge of the bearing surface (141) to the center of the bearing surface (141), at least a portion of the bearing surface (141) gradually decreases in height along the third direction (Z).

9. The back contact battery according to claim 8, characterized in that, Along the second direction (Y), from the edge of the bearing surface (141) toward the center of the bearing surface (141), at least a portion of the bearing surface (141) gradually decreases in height along the third direction (Z).

10. A back-contact stacked battery, characterized in that, The back-contact stacked battery includes a back-contact bottom battery (10b) and a perovskite top battery (10a), wherein the perovskite top battery (10a) is electrically connected to the front side of the back-contact bottom battery (10b), and the back-contact bottom battery (10b) is the back-contact battery according to any one of claims 1-9.

11. A photovoltaic module, characterized in that, The photovoltaic module includes the back-contact battery as described in any one of claims 1-9 or the back-contact tandem battery as described in claim 10.

Images