BC solar cell and electrode structure thereof

Abstract

The invention relates to a BC solar cell and an electrode structure thereof. The electrode structure comprises main grids arranged at intervals in the transverse direction, auxiliary grids arranged on the main grids at intervals in the longitudinal direction and bonding pads arranged on the intersection points of the main grids and the auxiliary grids, the main grids comprise positive electrode main grids and negative electrode main grids which are arranged alternately, the negative electrode main grids are silver main grids, and the auxiliary grids are silver main grids. The positive electrode main grid comprises a silver main grid and an aluminum main grid, bonding pads on the silver main grid are silver bonding pads, and the aluminum main grid comprises a silver bonding pad and an aluminum bonding pad. According to the electrode of the BC solar cell, slurry corrosion is effectively reduced, the metal composite area is reduced, the current conduction performance is improved, meanwhile, the welding tension is guaranteed, and the welding reliability is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a BC solar cell and an electrode structure thereof. Background Art

[0002] The front of the BC (back contact) solar cell is not covered by metal, and the positive and negative electrodes are on the back. The silver / aluminum main grid and silver / aluminum auxiliary grid are attached to the back for electrical conduction, so the PN junction and poly structure of the BC solar cell are also on the back. Since there is no metal grid line covering the front, the BC solar cell can maximize the light recombination area, improve the short-circuit current Isc, and the front passivation layer does not need laser grooving and metal corrosion, and has excellent field passivation and anti-reflection effects. At the same time, the back is covered with two kinds of metal grid lines, silver and aluminum, which increases the metal auxiliary grid area while reducing the series resistance, and greatly improves the current density and fill factor.

[0003] Usually, in order to ensure the welding tension on the back of BC solar cells, a larger area of ​​pads is printed on the electrode main grid. However, the slurry used for printing the pads is corrosive to a certain extent. During sintering, the slurry will penetrate the passivation layer and contact the silicon substrate, resulting in excessive metal recombination and affecting the electrical performance.

[0004] Therefore, there is an urgent need for a BC solar cell electrode structure that can ensure welding tension while reducing the metal composite area. Summary of the invention

[0005] Based on this, it is necessary to provide a BC solar cell and its electrode structure to address the above problems. The BC solar cell electrode provided by the present invention can effectively reduce slurry corrosion, reduce metal composite area, improve current conduction performance, and at the same time ensure welding tension and improve welding reliability.

[0006] The present invention provides an electrode of a BC solar cell, comprising a main grid arranged at intervals in a lateral direction, a secondary grid arranged at intervals in a longitudinal direction on the main grid, and a welding pad arranged at the intersection of the main grid and the secondary grid, wherein the main grid comprises a positive main grid and a negative main grid arranged alternately,

[0007] Among them, the negative electrode main grid is a silver main grid, the positive electrode main grid includes a silver main grid and an aluminum main grid, the pads on the silver main grid are all silver pads, and the aluminum main grid includes a silver pad and an aluminum pad.

[0008] In one of the embodiments, the aluminum main grid includes 10% to 70% silver pads and 30% to 90% aluminum pads.

[0009] In one of the embodiments, on the aluminum main grid, the number of the silver pads is greater than the number of the aluminum pads.

[0010] In one of the embodiments, on the aluminum main grid, the pads near both ends in the longitudinal direction are all aluminum pads, and the number of the pads accounts for 20% to 40% of the total number of pads on the aluminum main grid.

[0011] In one embodiment, the minimum distance between the aluminum pad on the aluminum main grid and the two ends of the gate of the aluminum main grid is H1, and the minimum distance between the silver pad on the silver main grid and the two ends of the gate of the silver main grid is H2, and H1≤H2.

[0012] In one of the embodiments, on the main grid, the ratio of the number of the pads to the number of the secondary grids is less than or equal to 1:10.

[0013] In one of the embodiments, in the positive electrode main grid, the proportion of the aluminum main grid is less than or equal to 40%.

[0014] In one embodiment, the minimum distance between the end point of the positive electrode sub-grid and the adjacent negative electrode main grid in the lateral direction is 0.2 mm to 1 mm.

[0015] In one of the embodiments, the minimum distance between the end point of the negative electrode sub-grid and the adjacent positive electrode main grid in the lateral direction is 0.2 mm to 1 mm.

[0016] In the electrode structure of the above-mentioned BC solar cell, the positive aluminum main grid includes a silver pad and an aluminum pad, which effectively reduces the corrosion of the slurry on the passivation layer, avoids excessive contact between the slurry and the silicon substrate, thereby reducing the metal composite area and improving the current conduction performance. At the same time, it can ensure the welding tension, improve the adhesion of the welding strip on the aluminum main grid, prevent the welding strip from falling off, and thus improve the welding reliability.

[0017] The present invention also provides a BC solar cell, wherein the BC solar cell comprises the electrode as described above.

[0018] The above-mentioned BC solar cell has excellent welding reliability and high cell conversion efficiency and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 Schematic diagram of the electrode structure of a BC solar cell in one embodiment of the present invention.

[0021] Figure numerals: 1-silver main grid; 2-aluminum main grid; 3-silver secondary grid; 4-aluminum secondary grid; 5-silver pad; 6-aluminum pad. DETAILED DESCRIPTION

[0022] For ease of understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific implementation methods or embodiments, and are not intended to limit the present invention. The optional scope of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of related listed items, and the combinations include any two related listed items, any more related listed items, or all related listed items.

[0024] like Figure 1 FIG. 1 is a schematic diagram of an electrode structure of a BC solar cell in one embodiment of the present invention, comprising:

[0025] A main grid arranged at intervals in the transverse direction, a secondary grid arranged at intervals in the longitudinal direction on the main grid, and a pad arranged at the intersection of the main grid and the secondary grid, wherein the main grid extends in the longitudinal direction, the secondary grid extends in the transverse direction, and the pad is arranged at the intersection of the main grid and the secondary grid;

[0026] Furthermore, the main grid includes a positive main grid and a negative main grid alternately arranged, the negative main grid is a silver main grid 1, the positive main grid includes a silver main grid 1 and an aluminum main grid 2, the pads on the silver main grid 1 are all silver pads 5, and the aluminum main grid 2 includes a silver pad 5 and an aluminum pad 6.

[0027] In the electrode structure of the above-mentioned BC solar cell, the positive aluminum main grid includes a silver pad and an aluminum pad, which effectively reduces the corrosion of the slurry on the passivation layer, avoids excessive contact between the slurry and the silicon substrate, thereby reducing the metal composite area and improving the current conduction performance. At the same time, it can ensure the welding tension, improve the adhesion of the welding strip on the aluminum main grid, prevent the welding strip from falling off, and thus improve the welding reliability.

[0028] It should be noted that the main grid includes a plurality of positive main grids and negative main grids that are alternately arranged at intervals. Each main grid includes a plurality of auxiliary grids arranged at intervals. The present invention has no special restrictions on the number of the main grids and the auxiliary grids. The number of auxiliary grids on each main grid can be the same or different. The pads on the main grid are used to realize the welding of the welding tape and the battery series connection. The present invention has no special restrictions on the shape of the pads.

[0029] In one embodiment, in the positive main grid, the proportion of the number of the aluminum main grids 2 is less than or equal to 40%, that is, in the positive main grid, if the proportion of the number of the aluminum main grids 2 to the total number of the positive main grids is a, then 0 < a ≤ 40%, including but not limited to any point value or the range value between any two of 1%, 2%, 5%, 10%, 15%, 20%, 30%, 40%.

[0030] It should be noted that the present invention has no special restrictions on the transverse arrangement positions of the silver main grids 1 and the aluminum main grids 2 in the positive main grid. For example, as Figure 1 shown, in one embodiment of the present invention, the two positive main grids adjacent to the silver main grid 1 in the positive main grid can both be silver main grids 1, or can be one silver main grid 1 and one aluminum main grid 2; in another embodiment, the two positive main grids adjacent to the silver main grid 1 in the positive main grid can also both be aluminum main grids 2.

[0031] It can be understood that the silver auxiliary grids 3 are arranged at intervals longitudinally on the silver main grid 1, the aluminum auxiliary grids 4 are arranged at intervals longitudinally on the aluminum main grid 2, and the auxiliary grids on two adjacent main grids do not contact each other.

[0032] In one embodiment, the minimum distance between the transverse end points of the positive auxiliary grid and the adjacent negative main grid is 0.2 mm to 1 mm, including but not limited to any point value or the range value between any two of 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm.

[0033] It can be understood that the positive auxiliary grid is the silver auxiliary grid 3.

[0034] In one embodiment, the minimum distance between the transverse end points of the negative auxiliary grid and the adjacent positive main grid is 0.2 mm to 1 mm.

[0035] It can be understood that the distances between the transverse end points of the auxiliary grids on any main grid and the adjacent main grid can be the same or different; the distances between the two transverse end points of any auxiliary grid and the adjacent negative main grid can be the same or different.

[0036] In one embodiment, on the main grid, the ratio of the number of the pads to the number of the sub-grids is less than or equal to 1:10. That is, on any main grid, if the ratio of the number of the solder pads to the number of the sub-grids is b, then 0 < b ≤ 10%, including but not limited to any value among 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or the range values between any two of them, which is beneficial to improving the current conduction performance, and at the same time increasing the light absorption area, thus being beneficial to improving the battery efficiency.

[0037] It should be noted that the number of the sub-grids, the number of the pads, and the ratio of the number of the pads to the number of the sub-grids on each main grid can be the same or different.

[0038] In one embodiment, on the aluminum main grid 2, it includes 10% - 70% silver pads 5 and 30% - 90% aluminum pads 6, which is beneficial to reducing the corrosion of the paste to the passivation layer, improving the current conduction performance, and at the same time ensuring the welding tensile force.

[0039] It should be noted that when the number of the aluminum main grids is greater than or equal to 2, the number of the pads on each aluminum main grid 2 can be the same or different, and the number of the silver pads 5 and the aluminum pads 6 on each aluminum main grid 2 can be the same or different.

[0040] Preferably, on the aluminum main grid 2, the number of the silver pads 5 is greater than the number of the aluminum pads 6. That is, on any aluminum main grid 2, the proportion of the number of the silver pads 5 is greater than 50%, including but not limited to any value among 51%, 53%, 55%, 60%, 65%, 70% or the range values between any two of them, and the proportion of the number of the aluminum pads 6 is less than 50%, including but not limited to any value among 49%, 47%, 45%, 40%, 35%, 30% or the range values between any two of them, which is beneficial to further reducing the corrosion of the paste to the passivation layer, improving the current conduction performance, and at the same time ensuring the welding tensile force.

[0041] More preferably, on the aluminum main grid 2, the pads near the longitudinal two ends are all the aluminum pads 6, and the number accounts for 20% - 40% of the total number of the pads on the aluminum main grid 2, including but not limited to any value among 20%, 22%, 25%, 28%, 30%, 33%, 35%, 38%, 40% or the range values between any two of them. When being prepared, the tensile force received is mainly dispersed at the two ends of the main grid, which is beneficial to further ensuring the welding tensile force, improving the adhesion stability of the solder strip, and then improving the current conduction performance.

[0042] It can be understood that the number of the aluminum pads 6 near the longitudinal two ends on each aluminum main grid 2 can be the same or different; the present invention has no special restrictions on the types and position distributions of the pads other than those near the longitudinal two ends. For example, as Figure 1As shown, in one embodiment of the present invention, on an aluminum main grid 2, except that both longitudinal ends are aluminum pads 6, the two pads adjacent to the silver pad 5 can be both silver pads 5, or one silver pad 5 and one aluminum pad 6; in another embodiment, the two pads adjacent to the silver pad 5 can also be both aluminum pads 6.

[0043] In one embodiment, the minimum distance between the aluminum pad on the aluminum main grid and the two ends of the gate of the aluminum main grid is H1, and the minimum distance between the silver pad on the silver main grid and the two ends of the gate of the silver main grid is H2, H1≤H2, which is conducive to further ensuring the welding tension, improving the adhesion stability of the welding strip, and thus improving the current conduction performance.

[0044] It can be understood that the distance between the aluminum pad 6 closest to the silicon substrate on each aluminum main grid 2 and the silicon substrate is greater than or equal to the distance between the silver pad 5 closest to the silicon substrate on each silver main grid 1 and the silicon substrate.

[0045] In one embodiment, the method for preparing the electrode of the BC solar cell described in the present invention includes the following steps: printing silver paste on the silver main grid 1, the silver sub-grid 3, and the silver pad 5; printing aluminum paste on the aluminum main grid 2, the aluminum sub-grid 4, and the aluminum pad 6; and printing insulating ink after sintering to obtain a positive electrode and a negative electrode.

[0046] Specifically, the silver paste includes 70% to 90% of silver powder, 3% to 7% of glass frit, and the remainder of an organic binder and a solvent.

[0047] In one embodiment, the silver powder has a grain size of 2 μm to 15 μm and a purity of about 99%, which is beneficial to further improve the current transmission performance.

[0048] In one embodiment, the glass material is selected from at least one of PbO, B2O3, SiO2, BiO3, ZnO and TiO2, which is conducive to corrosion penetration of the passivation anti-reflection layer, promotes electrical contact between the silver powder and the silicon emitter region, and is conducive to improving the current transmission performance.

[0049] Preferably, the mass fraction of PbO in the glass material is 1% to 6%, which is beneficial to increase the generation of recrystallized particles and the formation of a tunnel conductive channel at the interface between the silver paste and the battery emitter, thereby reducing contact resistance and further improving current transmission performance.

[0050] The present invention also provides a BC solar cell, wherein the BC solar cell comprises the electrode as described above.

[0051] It can be understood that the BC solar cell can be an IBC solar cell or a TBC solar cell.

[0052] The above-mentioned BC solar cell has excellent welding reliability and high cell conversion efficiency and has broad application prospects.

[0053] The BC solar cell and its electrode structure will be further described below through the following specific examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific conditions are specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are followed. The reagents or instruments used without indicating the manufacturer are all conventional products that can be purchased commercially.

[0054] Example 1

[0055] The BC solar cell includes a silicon substrate, the front side of the silicon substrate includes a passivation anti-reflection layer, the back side of the silicon substrate includes an N region, a P region and an isolation region, the N region includes a tunneling oxide layer, a phosphorus-doped polysilicon layer, a passivation anti-reflection layer and a negative electrode arranged in layers, the P region includes a tunneling oxide layer, a boron-doped polysilicon layer, a passivation anti-reflection layer and a positive electrode arranged in layers, and the isolation region includes a passivation anti-reflection layer; in the electrode structure composed of the positive electrode and the negative electrode, the positive main grid and the negative main grid are arranged alternately in the horizontal direction, wherein each negative main grid is a silver main grid, and in the positive main grid, the number of aluminum main grids and silver main grids accounts for 50% each, and the aluminum main grid in the positive main grid and the silver main grid in the positive main grid are arranged alternately.

[0056] The auxiliary grids on the main grid are arranged in the longitudinal direction, and the distances between the two end points of the auxiliary grid in the transverse direction and the two adjacent main grids are both 0.2 mm. The ratio of the number of pads on each main grid to the number of auxiliary grids is 1:10.

[0057] The welding pads on each silver main grid are all silver welding pads, the ratio of the number of silver welding pads to aluminum welding pads on each aluminum main grid is 1:1, the welding pads close to the two longitudinal end points of the aluminum main grid are all aluminum welding pads, and the proportion of aluminum welding pads close to the two longitudinal end points is 40%, and the proportion of aluminum welding pads at the upper and lower ends is 20% each; and the distance from the aluminum welding pad closest to the silicon substrate on all aluminum main grids to the silicon substrate is greater than the distance from the silver welding pad closest to the silicon substrate on all silver main grids to the silicon substrate.

[0058] Example 2

[0059] The difference between Example 2 and Example 1 is that, in the electrode structure of the BC solar cell, the positive electrode main grid and the negative electrode main grid are arranged alternately in the horizontal direction, wherein the negative electrode main grids are all silver main grids, and in the positive electrode main grids, the number of aluminum main grids accounts for 40%, and the number of silver main grids accounts for 60%, and the aluminum main grid in the positive electrode main grid and the silver main grid in the positive electrode main grid are arranged alternately.

[0060] The auxiliary grids on the main grid are arranged in the longitudinal direction, and the distances between the two end points of the auxiliary grid in the transverse direction and the two adjacent main grids are both 1 mm, and the ratio of the number of pads on each main grid to the number of auxiliary grids is 1:20.

[0061] The welding pads on each silver main grid are all silver welding pads, the number of silver welding pads on each aluminum main grid accounts for 60%, the number of aluminum welding pads accounts for 40%, the welding pads close to the two longitudinal end points of the aluminum main grid are all aluminum welding pads, and the number of aluminum welding pads close to the two longitudinal end points accounts for 30%, the number of aluminum welding pads on one end close to the silicon substrate accounts for 20%, and the number of aluminum welding pads close to the other end of the main grid accounts for 10%; and the distance from the aluminum welding pad closest to the silicon substrate on all aluminum main grids to the silicon substrate is greater than the distance from the silver welding pad closest to the silicon substrate on all silver main grids to the silicon substrate.

[0062] Example 3

[0063] The difference between Example 3 and Example 1 is that, in the electrode structure of the BC solar cell, the positive main grid and the negative main grid are arranged alternately in the horizontal direction, wherein the negative main grids are all silver main grids, and among the positive main grids, the number of aluminum main grids accounts for 10%, and the number of silver main grids accounts for 90%, and the aluminum main grid is arranged in the middle position of all the positive main grids, and the silver main grids are arranged on both sides of all the positive main grids.

[0064] The auxiliary grids on the main grid are arranged in the longitudinal direction, and the distances between the two end points of the auxiliary grid in the transverse direction and the two adjacent main grids are both 0.5 mm. The ratio of the number of pads on each main grid to the number of auxiliary grids is 1:30.

[0065] The pads on each silver main grid are all silver pads, the number of silver pads on each aluminum main grid accounts for 90% and the number of aluminum pads accounts for 10%, and all aluminum pads are arranged at the two longitudinal ends of the aluminum main grid, and the aluminum pads at the upper and lower ends account for 5% each; and the distance from the aluminum pad closest to the silicon substrate on all aluminum main grids to the silicon substrate is equal to the distance from the silver pad closest to the silicon substrate on all silver main grids to the silicon substrate.

[0066] Comparative Example 1

[0067] The difference between Comparative Example 1 and Example 1 is that, in the electrode structure of the BC solar cell, the positive electrode main grid and the negative electrode main grid are arranged alternately in the horizontal direction, wherein the negative electrode main grids are all silver main grids, and in the positive electrode main grid, the number of aluminum main grids and silver main grids accounts for 50% each, and the aluminum main grid in the positive electrode main grid and the silver main grid in the positive electrode main grid are arranged alternately.

[0068] The auxiliary grids on the main grid are arranged in the longitudinal direction, and the distances between the two end points of the auxiliary grid in the transverse direction and the two adjacent main grids are both 0.2 mm. The ratio of the number of pads on each main grid to the number of auxiliary grids is 1:10.

[0069] The pads on each silver main grid are silver pads, the pads on each aluminum main grid are aluminum pads, and the distance from the aluminum pad closest to the silicon substrate on all aluminum main grids to the silicon substrate is greater than the distance from the silver pad closest to the silicon substrate on all silver main grids to the silicon substrate.

[0070] The BC solar cells of Examples 1 to 3 and Comparative Example 1 were subjected to a welding tensile test. Manual welding was performed using a 63-37 (Sn-Pb) solder ribbon commonly used in the industry. A 180° tensile force was used to evaluate the adhesion between the solder ribbon and the slurry and silicon wafer. During the test, the solder ribbon was peeled off at a speed of 5 mm / s, and the value was recorded every 10 mm. After the test was completed, the average value of all the data was taken.

[0071] The BC solar cells of Examples 1 to 3 and Comparative Example 1 were subjected to IV tests to measure conversion efficiency (Eta), short circuit current (Isc), open circuit voltage (Uoc), fill factor (FF) and reverse saturation current (IRev).

[0072] The test results of the aging tensile force and electrical properties of the solder strips of the BC solar cells of Examples 1 to 3 and Comparative Example 1 are shown in Table 1.

[0073] Table 1

[0074]

[0075] According to Table 1, under the same test conditions, the welding tension of the BC solar cells of Examples 1 to 3 is significantly greater than that of the BC solar cells of Comparative Example 1; the BC solar cells of Examples 1 to 3 have higher short-circuit current, open-circuit voltage, fill factor and lower reverse saturation current, so the BC solar cells of Examples 1 to 3 have higher conversion efficiency, while the short-circuit current, open-circuit voltage, fill factor and conversion efficiency of the BC solar cell of Comparative Example 1 are significantly lower, and the reverse saturation current is higher. Therefore, the electrode of the BC solar cell provided by the present invention can effectively reduce slurry corrosion, reduce metal composite area, improve current conduction performance, and at the same time ensure welding tension, improve welding reliability, and thus effectively increase the conversion efficiency of the BC solar cell, and has a broad application prospect.

[0076] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0077] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An electrode of a BC solar cell, comprising a main grid arranged at intervals in a lateral direction, a secondary grid arranged at intervals in a longitudinal direction on the main grid, and a welding pad arranged at the intersection of the main grid and the secondary grid, wherein the main grid comprises a positive main grid and a negative main grid arranged alternately, characterized in that: The negative electrode main grid is a silver main grid, the positive electrode main grid includes a silver main grid and an aluminum main grid, the pads on the silver main grid are all silver pads, and the aluminum main grid includes a silver pad and an aluminum pad.

2. The electrode of the BC solar cell according to claim 1, characterized in that: The aluminum main grid includes 10% to 70% of silver pads and 30% to 90% of aluminum pads.

3. The electrode of the BC solar cell according to claim 1, characterized in that: On the aluminum main grid, the number of the silver pads is greater than the number of the aluminum pads.

4. The electrode of the BC solar cell according to claim 1 or 3, characterized in that: On the aluminum main grid, the pads close to both ends of the grid are all aluminum pads, and the number of pads accounts for 20% to 40% of the total number of pads on the aluminum main grid.

5. The electrode of the BC solar cell according to claim 4, characterized in that: The minimum distance between the aluminum pad on the aluminum main grid and the two ends of the gate of the aluminum main grid is H1, and the minimum distance between the silver pad on the silver main grid and the two ends of the gate of the silver main grid is H2, H1≤H2.

6. The electrode of the BC solar cell according to claim 1, characterized in that: On the main grid, the ratio of the number of the pads to the number of the secondary grids is less than or equal to 1:

10.

7. The electrode of the BC solar cell according to claim 1, characterized in that: In the positive electrode main grid, the proportion of the aluminum main grid is less than or equal to 40%.

8. The electrode of the BC solar cell according to claim 1, characterized in that: The minimum distance between the endpoint of the positive electrode sub-grid and the adjacent negative electrode main grid is 0.2 mm to 1 mm.

9. The electrode of the BC solar cell according to claim 1, characterized in that: The minimum distance between the endpoint of the negative electrode sub-grid and the adjacent positive electrode main grid is 0.2 mm to 1 mm.

10. A BC solar cell, characterized in that: The BC solar cell comprises the electrode according to any one of claims 1 to 9.

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