Solar cells, solar strings and photovoltaic modules

Abstract

The present invention provides a cell, a cell string and a photovoltaic module. The cell comprises a first doping region and a second doping region arranged on a surface of a substrate. The first doping region and the second doping region both comprise a main body arranged along a first direction and a finger-shaped portion connected to the main body. The finger-shaped portions of the first doping region and the second doping region are arranged in a forked finger shape along the first direction. An insulating layer is arranged at a position of the first finger-shaped portion of the first doping region close to the second main body of the second doping region; wherein the insulating layer at least covers the end of the first finger-shaped portion close to the second main body, and extends to the interval between the first finger-shaped portion and the second main body. The cell string comprises a cell and an electrical connector, and the electrical connector is bonded to at least two cell cells through a bonding layer. The photovoltaic module comprises at least one cell string.

Description

Technical Field

[0001] At least one embodiment of the present invention relates to the field of photovoltaic technology, and in particular to a battery cell, a battery string and a photovoltaic module. Background Art

[0002] In a back-contact cell, electrodes are arranged on different doped regions on the back side of the cell to form a positive electrode and a negative electrode.

[0003] The doped region includes a main body and a finger-shaped portion connected to the main body, wherein the main body is suitable for configuring a main gate, and the finger-shaped portion is suitable for configuring a secondary gate connected to the main gate. In order to prevent the main gate and the secondary gate of different polarities on different doped regions from being electrically connected, an insulating layer needs to be set on the secondary gate of different polarity adjacent to the main gate.

[0004] At present, the insulating layer only covers the end of the auxiliary grid, and there is a gap between the end of the insulating layer close to the main body of another doping region and the main body. The insulating layer in the gap is exposed to a strong electric field, which causes leakage and reduces the conversion efficiency of the battery cell. Summary of the invention

[0005] In order to solve at least one of the above-mentioned and other technical problems in the prior art, the present invention provides a battery cell, a battery string and a photovoltaic module, by covering the spacing area between the first finger-shaped portion and the second main body with an insulating layer so that there is no gap between the spacing area and the main body to prevent leakage.

[0006] An embodiment of the present invention provides a battery cell, comprising a first doping region and a second doping region arranged on a surface of a substrate, wherein the first doping region and the second doping region both comprise a main body portion arranged along a first direction and a finger portion connected to the main body portion, the finger portions of the first doping region and the second doping region are arranged in a forked finger shape along the first direction, and an insulating layer is arranged at a position of the first finger portion of the first doping region close to the second main body portion of the second doping region; wherein the insulating layer at least covers an end portion of the first finger portion close to the second main body portion, and extends to the spacing area between the first finger portion and the second main body portion.

[0007] According to an embodiment of the present invention, the second main body portion protrudes from the surface of the substrate, and the first finger-shaped portion is either located within the substrate; the first finger-shaped portion protrudes from the surface of the substrate or is located within the substrate; and, in the orthographic projection along the thickness direction of the substrate, the spacing area is formed between the end of the second main body portion close to the first finger-shaped portion and the end of the first finger-shaped portion close to the second main body portion.

[0008] According to an embodiment of the present invention, the cell further comprises a first sub-grid disposed on the first finger portion and electrically connected to the first finger portion, and the insulating layer covers an end portion of the first sub-grid close to the second main body portion.

[0009] According to an embodiment of the present invention, the insulating layer extends from the spacing area to the second main body portion.

[0010] According to an embodiment of the present invention, a thickness of a portion of the insulating layer located in the spacing region is greater than a thickness of a portion of the insulating layer located on the second main body portion.

[0011] According to an embodiment of the present invention, the first doping region and the second doping region protrude from the surface of the substrate, and the first doping region and the second doping region have different heights.

[0012] According to an embodiment of the present invention, the battery cell further includes a passivation layer, the passivation layer covers the spacer area, and the insulating layer covers the passivation layer in the spacer area.

[0013] According to an embodiment of the present invention, the first doping region and / or the second doping region comprises at least one of an in-situ doping region, polycrystalline silicon, amorphous silicon, and microcrystalline silicon.

[0014] According to an embodiment of the present invention, one of the first doping region and the second doping region is an N-type doping region, and the other is a P-type doping region.

[0015] According to an embodiment of the present invention, the finger portion is formed on one side of the main body portion and extends along a second direction intersecting with the first direction.

[0016] According to an embodiment of the present invention, the finger portions are formed on both sides of the main body portion and extend along a second direction intersecting with the first direction.

[0017] An embodiment of the present invention further provides a battery string, comprising the above-mentioned battery cells and an electrical connector, wherein the above-mentioned electrical connector is bonded to at least two of the above-mentioned battery cells through a bonding layer.

[0018] According to an embodiment of the present invention, the bonding layer is disposed on the second main body portion of the battery cell, and the bonding layer overlaps the insulating layer.

[0019] An embodiment of the present invention further provides a photovoltaic assembly, comprising at least one battery string.

[0020] According to the battery cell, battery string and photovoltaic module provided by the present invention, the isolation area between the first finger-shaped portion and the second main body portion is covered by an insulating layer, which is suitable for preventing the bonding layer used for welding from entering the isolation area to prevent leakage caused by a large electric field strength between the bonding layer in the isolation area and the electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic diagram of a partial top view of a battery cell according to an exemplary embodiment of the present invention;

[0022] Figure 2 yes Figure 1 a partial enlarged view of the first finger portion of the illustrated exemplary embodiment;

[0023] Figure 3 yes Figure 2 a partial cross-sectional view of the portion A1-A2 of the illustrated exemplary embodiment showing an implementation of a hybrid back contact cell; and

[0024] Figure 4 is a partial cross-sectional view of a battery cell of another exemplary embodiment, showing an implementation of a TBC battery.

[0025] In the drawings, the meanings of the reference numerals are as follows:

[0026] 1. Insulation layer;

[0027] 2. The first main grid;

[0028] 3. The first secondary grid;

[0029] 4. Second main grid;

[0030] 5. Second auxiliary grid;

[0031] 6. a first doped region;

[0032] 601, first main body;

[0033] 602, first finger-shaped portion;

[0034] 7. a second doping region;

[0035] 701, second main body;

[0036] 702, second finger-like portion;

[0037] 8. Substrate;

[0038] 9. Passivation layer;

[0039] 10. Interface layer. DETAILED DESCRIPTION

[0040] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0041] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0042] All terms used herein, including technical and scientific terms, have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0043] When using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted as the meaning of the expression generally understood by those skilled in the art. For example, "a system having at least one of A, B, and C" should include but not be limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc. When using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted as the meaning of the expression generally understood by those skilled in the art. For example, "a system having at least one of A, B, or C" should include but not be limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.

[0044] The back of the back contact battery (i.e., BC battery) is provided with a first doping region and a second doping region, each of which includes a main body and a finger-shaped portion, wherein the main body is suitable for providing a main grid electrically connected to the main body, and the finger-shaped portion is suitable for providing a secondary grid electrically connected to the main grid of the same polarity, so as to form a positive electrode and a negative electrode respectively on different doping regions. In order to insulate the main grid from the secondary grid of the opposite polarity, an insulating layer needs to be provided at the end of the secondary grid of the opposite polarity adjacent to the main grid, so as to avoid the occurrence of a short circuit problem caused by the connection between the main grid and the secondary grid of the opposite polarity.

[0045] At present, the insulating layer provided only covers the end of the auxiliary grid, but does not cover the spacer between the first finger-shaped portion of the first doping region and the second main body portion of the second doping region, and there is a gap between the end of the insulating layer close to the second main body portion and the second main body portion in the spacer. During the manufacturing process of the battery cell, the bonding layer (such as solder, including but not limited to solder) is easy to spread and embed into the above gap, so that a large electric field strength is formed between the bonding layer and the auxiliary grid after welding is completed. The excessive electric field strength will cause the charge to leak from the weak area (such as the thinner part) of the insulating layer, causing leakage, thereby affecting the conversion efficiency of the battery cell.

[0046] In view of this, how to provide a battery cell, battery string and photovoltaic module that can effectively improve the insulation performance of the insulation layer and prevent leakage has become a technical problem that needs to be solved urgently.

[0047] Figure 1 It is a schematic diagram of a partial top view of a battery cell according to an illustrative embodiment of the present invention.

[0048] According to the battery cell provided by the present invention, Figure 1 As shown, it includes a first doping region 6 and a second doping region 7 arranged on a surface of a substrate 8, and the first doping region 6 and the second doping region 7 both include a main body portion arranged along a first direction and a finger portion connected to the main body portion. The finger portions of the first doping region 6 and the second doping region 7 are arranged in a forked finger shape along the first direction, and an insulating layer 1 is provided at a position of the first finger portion 602 of the first doping region 6 close to the second main body portion 701 of the second doping region 7. The insulating layer 1 at least covers the end of the first finger portion 602 close to the second main body portion 701 (such as the right end of the first finger portion 602 covered by A1, and the left end of the first finger portion covered by A2), and extends to the spacing area between the first finger portion 602 and the second main body portion 701. In an illustrative embodiment, as Figure 1 As shown, one surface of the substrate 8 (eg Figure 1 The substrate is shielded by the first doping region 6 and the second doping region 7 (not shown). The first doping region 6 and the second doping region 7 are provided. In detail, the first doping region 6 includes a first main body 601 and a first finger portion 602, and the second doping region 7 includes a second main body 701 and a second finger portion 702, wherein the first main body 601 and the second main body 701 are both along the first direction (such as Figure 1 The first finger-shaped portion 602 and the second finger-shaped portion 702 extend from the main body (ie, the first main body 601 or the second main body 701) along the second direction (eg, Figure 1 X direction as shown) to the side away from the main body (as shown Figure 1Further, the first finger portion 602 of the first doping region 6 and the second finger portion 702 of the second doping region 7 are arranged in a first direction (eg, Figure 1 The concave-convex structures are arranged alternately in sequence along the first direction.

[0049] A first main gate 2 and a first sub-gate 3 are disposed on the first doping region 6, wherein the first main gate 2 is disposed along a first direction (eg Figure 1 The first auxiliary grid 3 is arranged on the first main body 601 along the second direction (as shown in the upper and lower directions). Figure 1 The first finger-shaped portion 602 is provided with a first auxiliary gate 3 (in the left and right directions shown in the figure), and the first auxiliary gate 3 is physically and electrically in contact with the first main gate 2. In addition, the first main gate 2 is connected to multiple first auxiliary gates 3, and the first main gate 2 is used to collect the current collected by multiple first auxiliary gates 3 (i.e., fine gates). In addition, a joint (e.g., a pad) may be provided on the first doped region 6, and at least two first auxiliary gates 3 are connected to one side of the joint. The joint may be connected to the first main gate 2, or may not be connected to the first main gate 2.

[0050] A second main gate 4 and a second auxiliary gate 5 are disposed on the second doping region 7, wherein the second main gate 4 is disposed along the first direction (eg Figure 1 The second main body 701 is arranged in the up-down direction as shown, and the second auxiliary grid 5 is arranged along the second direction (such as Figure 1 The second finger-shaped portion 702 is provided with a second sub-gate 5 in the left and right directions shown in the figure, and the second sub-gate 5 is physically and electrically in contact with the second main gate 4. In addition, the second main gate 4 is connected to a plurality of second sub-gates 5, and the second main gate 4 is used to collect the current collected by the plurality of second sub-gates 5 (i.e., fine gates). In addition, a joint (e.g., a pad) may be provided on the second doped region 4, and at least two second sub-gates 5 are connected to one side of the joint. The joint may be connected to the second main gate 4, or may not be connected to the second main gate 4.

[0051] When the electrical connector (such as welding strip, not shown) is arranged along the main grid, the electrical connector is easy to deviate and overlap with the opposite-sex auxiliary grid to cause a short circuit. Therefore, it is necessary to arrange an insulating layer 1 at the end of the opposite-sex auxiliary grid close to the same-sex fine grid to prevent short circuit. Figure 1 As shown, the insulating layer 1 is arranged at the end of the first sub-gate 3 close to the second main gate 4, and there are insulating blocks A1 and A2 in the figure. The figure only shows two insulating blocks schematically. It should be understood that the insulating layer 1 should be set at the end of each first sub-gate 3 close to the second main gate 4.

[0052] As an embodiment of the present application, the insulating layer 1 covers the ends of the first sub-gate 3 and the second sub-gate 5, and the insulating layer 1 extends into the spacer, preferably completely filling the spacer. The spacer is an electrically isolated region between the first finger portion 602 and the second main body portion 701, or an electrically isolated region between the second finger portion 702 and the first main body portion 601.

[0053] In an illustrative embodiment, Figure 1 As shown, the insulating layer 1 (for clarity of the diagram, Figure 1 Only two insulating layers 1 are schematically shown in the figure. The insulating layer 1 is disposed in the isolation region (eg, Figure 1 In detail, the insulating layer 1 includes but is not limited to being configured as a rectangular structure, and the insulating layer 1 includes a plurality of block structures, each of which corresponds to the end position of the secondary gate. Further, the insulating layer 1 includes but is not limited to being made of insulating glue (such as green glue).

[0054] In such an embodiment, the isolation area between the first finger portion 602 and the second main body portion 701 is covered by the insulating layer 1. Thus, in the welding process, since the isolation area is covered by the insulating layer 1, the bonding layer used for welding (including but not limited to solder, such as solder) can be effectively prevented from entering the isolation area, so as to prevent the bonding layer from forming an excessively large electric field strength between the bonding layer and the electrode (such as the auxiliary grid) in the spacing area, thereby avoiding the occurrence of leakage, and a thicker insulating layer is also beneficial in preventing the insulating layer from being punctured or broken down.

[0055] According to an embodiment of the present invention, Figure 1 As shown, the finger portion is formed on one side of the main body portion and extends along a second direction intersecting with the first direction.

[0056] In an illustrative embodiment, Figure 1 As shown, the second doping region 7 is arranged at the edge of the substrate (such as arranged as Figure 1 In detail, a second finger portion 702 is provided on one side of the second main portion 701 of the second doping region 7 located at the edge of the substrate close to the first doping region 6 (such as the right side of the first doping region located at the left end of the substrate, and the left side of the first doping region located at the right end). Further, the plurality of second finger portions 702 are arranged along the first direction (such as Figure 1 The Y direction as shown) is arranged with intervals.

[0057] According to an embodiment of the present invention, Figure 1 As shown, the finger portions are formed on both sides of the main body portion and extend along a second direction intersecting with the first direction.

[0058] In an illustrative embodiment, Figure 1As shown, the second doping region 7 is arranged in the middle of the substrate (such as arranged in Figure 1 In detail, the second main body 701 of the second doping region 7 located in the middle of the substrate (such as Figure 1 The second finger-shaped portion 702 is disposed on both the left and right sides of the second main body 701. Further, the second finger-shaped portion 702 located on the second main body 701 is symmetrical along the midline of the second main body 701 (as shown in FIG. Figure 1 In another embodiment, the leftmost portion may be the first doping region 6, and the rightmost portion may be the second doping region 7. From the center line of the cell, the doping regions on both sides are asymmetrical structures.

[0059] According to the cell provided by the present invention, the first doping region 6 and / or the second doping region 7 include but are not limited to at least one of an in-situ doping region, polycrystalline silicon, amorphous silicon, and microcrystalline silicon. Depending on the structure and material of the first doping region 6 and the second doping region 7, the cell may be a back contact cell of TopCON, HJT, PERC, or a hybrid back contact cell of at least two of TopCON, HJT, and PERC.

[0060] According to the cell provided by the present invention, the first doping region 6 and the second doping region 7 are doping regions of opposite types, wherein one of the first doping region 6 and the second doping region 7 is an N-type doping region and the other is a P-type doping region.

[0061] For example, a cell with an n-type silicon substrate as a substrate has a p-type doping region (i.e., the first doping region 6) and an n-type doping region (i.e., the second doping region 7) disposed on its back, wherein the electrode disposed on and connected to the p-type doping region is used as a positive electrode, and the electrode disposed on and connected to the n-type doping region is used as a negative electrode. Similarly, the p-type doping region can also be used as the second doping region 7, and the n-type doping region can also be used as the first doping region 1.

[0062] Figure 2 yes Figure 1 An enlarged partial view of the first finger of the exemplary embodiment is shown.

[0063] According to an embodiment of the present invention, Figure 2 As shown, the cell further includes a first sub-grid 3 disposed on the first finger-shaped portion 602 and electrically connected to the first finger-shaped portion 602. The insulating layer 1 covers the end of the first sub-grid 3 close to the second main body 701.

[0064] In an illustrative embodiment, Figure 1 and Figure 2 As shown, the first main body 601 is provided with a plurality of Figure 1The first finger portion 602 is provided with a first main grid 2 extending in the Y direction (as shown in FIG. 1 ), and the first finger portion 602 is provided with a first auxiliary grid 3 connected to the first main grid 2. Similarly, the second main portion 701 is provided with a first auxiliary grid 3 extending in the first direction (as shown in FIG. 1 ). Figure 1 The second finger-shaped portion 702 is provided with a second main gate 4 extending in the Y direction as shown in FIG. Figure 1 The first auxiliary gate 3 adjacent to the X direction (as shown) and the ... Figure 1 A disconnection portion is formed between the adjacent second auxiliary grids 5 (in the X direction shown in the figure) to accommodate the second main grid 4 or the first main grid 2 of different polarity to pass through.

[0065] In an illustrative embodiment, Figure 2 As shown, the end of the first auxiliary grid 3 covered by the insulating layer 1 is connected to the edge of the insulating layer 1 close to the second main grid 4 (as shown in FIG. Figure 2 The distance between the right edge of the insulating layer 1 on the left side (i.e. Figure 2 The distance d2 shown in FIG. 1 is configured to be larger than the distance between the end of the first auxiliary gate 3 covered by the insulating layer 1 and the second main body 701 (ie, as shown in FIG. 1 ). Figure 2 d1 as shown). Wherein, d2 includes but is not limited to being configured as 0.3 mm to 1.5 mm (i.e., 0.3 mm ≤ d2 ≤ 1.5 mm), and d1 includes but is not limited to being configured as 0.1 mm to 0.5 mm (i.e., 0.1 mm ≤ d1 ≤ 0.5 mm).

[0066] According to an embodiment of the present invention, Figure 2 As shown, the insulating layer 1 extends from the spacing area to the second main body 701 .

[0067] In an illustrative embodiment, Figure 2 As shown, in the orthographic projection along the thickness direction of the substrate 8, the width of the portion of the insulating layer 1 extending to the second main body portion 701 (ie, as shown in FIG. Figure 2 The d3) shown includes but is not limited to 100 microns to 500 microns (ie, 100 μm≤d3≤500 μm).

[0068] In such an embodiment, since d2 is configured to be greater than d1, the insulating layer 1 can be extended to the second main body 701. The insulating layer 1 spans the spacing area and extends to the second main body 701, so that the spacing area between the first finger portion 602 and the second main body 701 can be completely covered. This is also conducive to compensating the accuracy of the equipment for setting the insulating layer 1 (such as the accuracy of the screen for printing the insulating layer 1), so as to leave a design margin and prevent the problem that the insulating layer 1 cannot completely cover the spacing area due to the accuracy of the equipment.

[0069] According to an embodiment of the present invention, the thickness of the portion of the insulating layer 1 located in the spacer region is greater than the thickness of the portion located on the second body portion 701 .

[0070] In an illustrative embodiment, the spacer between the second main body 701 and the first finger-shaped portion 602 forms a recessed portion that is recessed toward the substrate 8 relative to the second main body 701 and the first finger-shaped portion 602. To this end, in the orthographic projection along the thickness direction of the substrate 8, the thickness of the portion of the insulating layer 1 located in the spacer is greater than the thickness of the portion of the insulating layer 1 located on the doping region (i.e., the first doping region 6 and the second doping region 7), and the thickness of the portion closer to the edge of the insulating layer 1 is smaller (i.e., the closer to the edge of the insulating layer, the thinner the insulating layer). In this way, it is helpful to further prevent leakage of this portion of the insulating layer 1, and because this portion is set thicker, it is also helpful to prevent the insulating layer 1 from being pierced by the electrode (such as the first sub-gate 3).

[0071] Figure 3 yes Figure 2 The partial cross-sectional view of the portion A1-A2 of the illustrated exemplary embodiment shows an implementation of a hybrid back contact cell.

[0072] According to an embodiment of the present invention, Figures 1 to 3 As shown in FIG. 1 , the second main body 701 protrudes from the surface of the substrate 8, or is located in the first finger-shaped portion 602. The first finger-shaped portion 602 protrudes from the surface of the substrate 8 or is located in the substrate 8; and in the orthographic projection along the thickness direction of the substrate 8, a spacing area is formed between the second main body 701 and the projection of the end of the first finger-shaped portion 602 close to the second main body 701 (i.e., Figure 3 The gap area shown).

[0073] In an illustrative embodiment, Figure 3 As shown, the second main body portion 701 protrudes from the surface of the substrate 8 (i.e., Figure 3 The first finger portion 602 is formed in the substrate 8, and the upper surface of the first finger portion 602 is configured to be substantially flush with the upper surface of the substrate 8. That is, in the thickness direction of the substrate 8 (such as Figure 3 In the vertical direction shown in FIG. 1 , the first doping region 6 (including the first finger portion 602) is lower than the second doping region 7 (including the second main body portion 701). In this way, during the process of printing the insulating layer 1, the insulating material (including insulating glue, such as green glue) still in a liquid state will not excessively extend from the lower first doping region 6 to the upper surface of the second doping region 7, thereby preventing the green glue from covering part of the second main gate 5. It should be understood that the embodiments of the present invention are not limited to this.

[0074] In another exemplary embodiment, not shown in the figure, the first finger portion 602 is configured to protrude from the surface of the substrate 8, and the second main body portion 701 is located in the substrate 8. In detail, the upper surface of the second main body portion 701 is configured to be substantially flush with the upper surface of the substrate 8, and a stepped spacing area is formed between the end of the first finger portion 602 close to the second main body portion 701 and the second main body portion 701. Further, the insulating layer 1 completely covers the spacing area, and extends toward the second main body portion 701 to a position that does not shield the second main gate 5 on the second main body portion 701.

[0075] In an illustrative embodiment, Figure 3 As shown, the second main body 701 of the second doped region 7 protrudes from the upper surface of the substrate 8, and forms a spacer region with a PN junction between the second main body 701 and the first finger portion 602 (ie, Figure 3 In detail, the second doping region 7 (including the first main body 701) includes but is not limited to using N-type polysilicon (i.e., N-POLY). Accordingly, the first doping region 6 (including the second finger-shaped portion 602) is configured as a P-type doping region that forms a PN junction with the N-type polysilicon, and the P-type doping region is an in-situ doping region. Further, the second finger-shaped portion 702 ( Figure 3 The first finger-shaped portion 602 and the second doping region 7 (not shown) form a hybrid back contact cell (i.e., a composite passivated back contact cell) with an interdigitated PN junction on the back of the cell. Similarly, the second doping region 7 may also be made of P-type polysilicon (i.e., P-POLY), and the corresponding first doping region 6 is configured as an N-type doping region.

[0076] According to an embodiment of the present invention, Figure 3 As shown, the cell further includes a passivation layer 9, the passivation layer 9 covers the spacing area, and the insulating layer 1 covers the passivation layer 9 in the spacing area.

[0077] In an illustrative embodiment, Figure 3 As shown, in the cross section along the thickness direction of the substrate 8, the passivation layer 9 of the cell is configured as a "Z-like" cross-sectional structure at the step of the spacer area, which covers the spacer area (i.e., Figure 3 The second doped region 7 and the substrate 8 are provided with an interface layer 10, and the insulating layer 1 covers the passivation layer 9. The passivation layer 9 includes but is not limited to silicon nitride, aluminum oxide or other materials suitable for covering the surface of the doped region and preventing the doped region from being oxidized and / or corroded; the interface layer 10 includes but is not limited to silicon oxide, aluminum oxide or other materials suitable for reducing the interface resistance at the interface formed between the doped region and the substrate and / or reducing the recombination loss of carriers at the interface.

[0078] Figure 4 is a partial cross-sectional view of a battery cell of another exemplary embodiment, showing an implementation of a TBC battery.

[0079] According to an embodiment of the present invention, Figure 3 As shown, the first doping region 6 and the second doping region 7 protrude from the surface of the substrate 8 , and the first doping region 6 and the second doping region 7 have different heights.

[0080] In an illustrative embodiment, Figure 4 As shown, the second main body portion 701 and the first finger portion 602 are both protruding from the surface of the substrate 8 (ie, Figure 4 The second main body 701 and the end of the first finger 602 close to the second main body 701 form a spacer. In detail, the second doping region 7 (including the first main body 701) includes but is not limited to using N-type polysilicon (i.e., N-POLY), and accordingly, the first doping region 6 (including the second finger 602) is configured as a P-type doping region that forms a PN junction with the N-type polysilicon. It should be understood that the embodiments of the present invention are not limited thereto.

[0081] In another exemplary embodiment, not shown in the figure, the second main body 701 and the first finger-shaped portion 602 are both located in the substrate 8. In detail, the upper surfaces of the second main body 701 and the first finger-shaped portion 602 are substantially flush with the upper surface of the substrate 8, and in the orthographic projection along the thickness direction of the substrate 8, the spacing between the projections of the second main body 701 and the second finger-shaped portion 602 forms a spacing area. Further, the second main gate 5 disposed on the second main body 701 and the first auxiliary gate 3 disposed on the first finger-shaped portion 602 protrude from the surface of the substrate, and the insulating layer 1 covers the end of the first auxiliary gate 3 close to the second main gate 5, completely covers the spacing area, and extends to a position where the second main gate 5 is not shielded.

[0082] In an illustrative embodiment, Figure 4 As shown, an interface layer 10 is provided between the second doping region 7 (including the first main body 701) and the first doping region 6 (including the second finger-shaped portion 602) and the substrate 8. The interface layer 10 can be a tunneling oxide layer to more effectively suppress the recombination of interface carriers. Furthermore, a passivation layer 9 is also provided in the recessed portion above the gap region between the first main body 701 and the second finger-shaped portion 602, and the passivation layer 9 forms a "quasi-concave" cross-sectional structure, with both ends of the passivation layer 9 extending to the first main body 701 and the second finger-shaped portion 602, respectively, that is, the TBC battery (i.e., tunneling back contact battery) is passivated based on the structure of the tunneling layer + Poly layer. The insulating layer 1 covers the passivation layer 9.

[0083] Furthermore, in the thickness direction of the substrate 8 (eg Figure 4 In the vertical direction shown in FIG. 1 ), the first doped region 6 (including the first finger portion 602) is higher than the second doped region 7 (including the second main body portion 701). Figure 3 Similar to the schematic embodiment shown, this is beneficial in that during the process of printing the insulating layer 1, the insulating material (including insulating glue, such as green glue) still in a liquid state can spread from the surface of the higher first doping region 6 to the lower second doping region 7.

[0084] In another embodiment, Figure 4 The structure may be a heterojunction back contact battery, wherein the interface layer 10 is an amorphous / microcrystalline intrinsic silicon layer, and the first doped region 6 (including the first finger portion 602) is higher than the second doped region 7 (including the second main portion 701) and may be an amorphous / microcrystalline doped silicon layer.

[0085] Based on the same inventive concept as the solar cell, the present invention also provides a solar cell string and a photovoltaic module.

[0086] The battery string provided by the present invention, which is not shown in the figure, comprises battery cells and electrical connectors (such as welding strips). The electrical connectors are bonded to at least two battery cells through a bonding layer.

[0087] Since the insulating layer 1 extends from one side of the heterosexual finger-shaped portion to at least the isolation region (or even to the homosexual main body portion), the insulating blocks (e.g. Figure 1 The area through which the welding strip passes defined by A1 and A2) is reduced, and when the bonding layer is disposed on the second main body 701 of the cell, at least one side of the welding strip overlaps the insulating layer 1, for example, overlaps the insulating layer 1 through the bonding layer. The width of the electrical connector is preferably greater than the width of the main grid, for example, it can be 250-600 microns.

[0088] In an exemplary embodiment, not shown in the figure, the bonding layer includes but is not limited to solder, such as solder. In detail, the bonding layer is provided at the bonding portion (such as a pad) formed by the electrical connection member (such as a solder strip) and the electrode of the battery cell. Further, when the bonding layer is welded, the bonding layer in a liquid state includes the insulating layer 1 diffused to one side (for example, diffused to Figure 1 The bonding layer is overlapped on the insulating layer 1 along a direction substantially parallel to the surface of the insulating layer 1. In this way, the portion of the bonding layer facing the insulating layer 1 is relatively flat, and even when laminated, the insulating layer 1 will not be pierced, thereby preventing the main grid and the auxiliary grid of opposite polarity from forming a short circuit.

[0089] The photovoltaic module provided by the present invention, not shown in the figure, comprises at least one battery string, wherein the at least one battery string is sealed by a front encapsulation layer and a back encapsulation layer, the front encapsulation layer comprises an upper layer of adhesive film near the front of the battery cell and a cover plate, and the back encapsulation layer comprises a lower layer of adhesive film near the back of the battery cell and a back plate.

[0090] It should also be noted that the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "back", "left", "right", etc., are only for reference to the drawings and are not intended to limit the scope of protection of the present invention. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present invention.

[0091] The embodiments of the present invention are described above. However, these embodiments are only for the purpose of illustration, and are not intended to limit the scope of the present invention. Although each embodiment is described above, it does not mean that the measures in each embodiment cannot be used in combination. The scope of the present invention is defined by the attached claims and their equivalents. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A battery cell, characterized in that: The invention comprises a first doping region (6) and a second doping region (7) arranged on a surface of a substrate (8), wherein the first doping region (6) and the second doping region (7) each comprise a main body portion arranged along a first direction and a finger portion connected to the main body portion, the finger portions of the first doping region (6) and the second doping region (7) are arranged in an interdigitated shape along the first direction, and an insulating layer (1) is arranged at a position of the first finger portion (602) of the first doping region (6) close to the second main body portion (701) of the second doping region (7); It also comprises a first auxiliary gate (3) arranged on the first finger-shaped portion (602) and electrically connected to the first finger-shaped portion (602), wherein the insulating layer (1) covers the end of the first auxiliary gate (3) close to the second main body portion (701); The insulating layer (1) at least covers the end of the first finger-shaped portion (602) close to the second main body portion (701), extends to the spacing area between the first finger-shaped portion (602) and the second main body portion (701), and completely fills the spacing area.

2. The battery cell according to claim 1, characterized in that: The second main body portion (701) protrudes from the surface of the substrate (8) or is located inside the substrate (8), and the first finger-shaped portion (602) protrudes from the surface of the substrate (8) or is located inside the substrate (8); and, in an orthographic projection along the thickness direction of the substrate (8), the spacing area is formed between the projection of the second main body portion (701) and the end of the first finger-shaped portion (602) close to the second main body portion (701).

3. The battery cell according to claim 1 or 2, characterized in that: The insulating layer (1) extends from the spacer area to the second main body (701).

4. The battery cell according to claim 3, characterized in that: The thickness of the portion of the insulating layer (1) located in the spacer area is greater than the thickness of the portion located on the second main body portion (701).

5. The battery cell according to claim 1 or 2, characterized in that: The first doping region (6) and the second doping region (7) protrude from the surface of the substrate (8), and the first doping region (6) and the second doping region (7) have different heights.

6. The battery cell according to claim 1 or 2, characterized in that: It also comprises a passivation layer (9), wherein the passivation layer (9) covers the spacer area, and the insulating layer (1) covers the passivation layer (9) in the spacer area.

7. The battery cell according to claim 1 or 2, characterized in that: The first doped region (6) and / or the second doped region (7) comprises at least one of polycrystalline silicon, amorphous silicon and microcrystalline silicon.

8. The battery cell according to claim 1 or 2, characterized in that: One of the first doping region (6) and the second doping region (7) is an N-type doping region, and the other is a P-type doping region.

9. The battery cell according to claim 1 or 2, characterized in that: The finger portion is formed at one side of the main body portion and extends along a second direction intersecting the first direction.

10. The battery cell according to claim 1 or 2, characterized in that: The finger portions are formed on both sides of the main body portion and extend along a second direction intersecting the first direction.

11. A battery string, characterized in that: The invention comprises a battery cell as claimed in any one of claims 1 to 10 and an electrical connector, wherein the electrical connector is bonded to at least two of the battery cells via a bonding layer.

12. The battery string according to claim 11, characterized in that: The bonding layer is arranged on the second main body portion (701) of the battery sheet, and the bonding layer overlaps the insulating layer (1).

13. A photovoltaic module, characterized in that: Comprising at least one battery string as claimed in claim 11 or 12.

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