A double-sided crystalline silicon solar cell

Abstract

The invention discloses a double-sided crystalline silicon solar cell, comprising a silicon substrate, a back passivation film and a back electrode, wherein the back passivation film is stacked on the back of the silicon substrate, the back passivation film is a blue film with a thickness of 60-90 nm, the back electrode comprises a back silver electrode in contact with the silicon substrate, a back aluminum main grid and a plurality of back aluminum sub-grids formed on the back passivation film, the back aluminum sub-grids intersect with the back aluminum main grid, the back silver electrode is nested in the back aluminum main grid, and the short-circuit current and conversion efficiency of the back of the solar cell can be improved.

Description

Technical Field

[0001] The invention belongs to the field of solar cells, and in particular relates to a double-sided crystalline silicon solar cell sheet. Background Art

[0002] P-type PERC bifacial cells have attracted widespread attention due to their simple preparation process, low cost, and bifacial power generation. According to the ITRPV forecast released by Semi in 2017, the share of bifacial monocrystalline cells in the future photovoltaic market will increase year by year, and the market share of bifacial cells will reach about 30% by 2027. Compared with the conventional PERC process, bifacial cells only use the back-printed aluminum grid line to replace the all-aluminum back field structure of conventional PERC cells on the basis of the original process. While maintaining the high conversion efficiency of the front side of the PERC cell, the back side can also generate electricity. However, the current cell efficiency of PERC cells is relatively low. Summary of the invention

[0003] In view of the above technical problems, the present invention aims to provide a double-sided crystalline silicon solar cell, which can improve the short-circuit current and conversion efficiency on the back side of the cell.

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A double-sided crystalline silicon solar cell comprises a silicon substrate, a back passivation film and a back electrode, wherein the back passivation film is stacked on the back of the silicon substrate, the back passivation film is a blue film with a thickness of 60-90 nm, the back electrode comprises a back silver electrode in contact with the silicon substrate, a back aluminum main grid and a plurality of back aluminum sub-grids formed on the back passivation film, the back aluminum sub-grids intersect with the back aluminum main grid, and the back silver electrode is embedded in the back aluminum main grid.

[0006] Furthermore, the back aluminum main grid includes a plurality of first main grid portions and a plurality of second main grid portions, the first main grid portions and the second main grid portions are staggered and arranged sequentially along the length direction of the back aluminum main grid, the width of the first main grid portion is greater than the width of the second main grid portion, and the back silver electrode is nested in the first main grid portion.

[0007] Furthermore, a gap is formed between the back silver electrode and the first main grid portion.

[0008] Furthermore, a window is provided on the first main grid portion to expose the back silver electrode.

[0009] Furthermore, the width of the window is smaller than the width of the back silver electrode.

[0010] Specifically, the width of the back silver electrode is 1.6-2.0 mm, and the width of the window is 1.5-1.8 mm.

[0011] Specifically, the width of the second main gate portion is 0.1-1.5 mm.

[0012] Furthermore, a laser positioning hole is provided on the solar cell sheet.

[0013] Furthermore, a plurality of the back aluminum main grids are arranged in parallel, and there is a laser positioning hole at each of the two ends of two back aluminum main grids located at the edge of the solar cell.

[0014] Furthermore, the back passivation film is aluminum oxide and silicon nitride film.

[0015] The present invention adopts the above solution, which has the following advantages compared with the prior art:

[0016] By using a blue film with a thickness of only 60~90nm as the back passivation film, the light trapping effect is increased, the conversion efficiency of the back side of the battery is improved, and it has a better appearance; at the same time, the back electrode pattern adopts a back aluminum main grid and back aluminum sub-grid design to reduce aluminum paste consumption and shading area, thereby increasing the short-circuit current on the back of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solution of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0018] Figure 1 A schematic diagram of a back electrode of a solar cell according to the present invention;

[0019] Figure 2 for Figure 1 A partial enlarged view of

[0020] Figure 3 for Figure 2 Sectional view along AA direction.

[0021] Among them, 1. back electrode; 11. back aluminum main grid; 111. first main grid; 1110. window; 112. second main grid; 113. laser positioning hole; 12. back aluminum sub-grid; 13. back silver electrode; 130. gap; 2. back passivation film; 3. silicon substrate. DETAILED DESCRIPTION

[0022] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0023] Reference Figure 1-3 As shown, the bifacial crystalline silicon solar cell according to the present invention comprises a silicon substrate 3, a back passivation film 2 and a back electrode 1, wherein the back passivation film 2 is stacked on the back of the silicon substrate 3, and the back electrode 1 is arranged on the back passivation film 2. In addition, the front side of the silicon substrate 3 also has a front structure for forming a battery, which is not the focus of the present invention and will not be described in detail here.

[0024] The back passivation film 2 is a blue film with a thickness of 60-90 nm, specifically a silicon nitride film. On the one hand, it increases the light trapping effect on the back of the solar cell and improves the back conversion efficiency of the cell; on the other hand, the back electrode 1 is formed on the blue film, which beautifies the appearance and has a better viewing effect.

[0025] The back electrode 1 includes a back silver electrode 13 in contact with the silicon substrate 3, a back aluminum main grid 11 formed on the back passivation film 2, and a plurality of back aluminum sub-grids 12, wherein the plurality of back aluminum sub-grids 12 and the plurality of back aluminum main grids 11 intersect to form a grid-like pattern, and the back silver electrode 13 is nested in the back aluminum main grid 11. Specifically, the preparation process of the back electrode 1 is as follows: firstly, a silver paste is screen-printed on the back passivation film 2, and then an aluminum paste is screen-printed around the silver paste, and then sintered, wherein the silver paste penetrates downwardly through the back passivation film 2 and forms contact with the silicon substrate 3 to form the back silver electrode 13, and the aluminum paste surrounding the silver paste forms the back aluminum main grid 11 located on the back passivation film 2, and the back silver electrode 13 formed after sintering is nested in the back aluminum main grid 11.

[0026] Furthermore, the back aluminum main grid 11 includes a plurality of first main grid portions 111 and a plurality of second main grid portions 112, the first main grid portions 111 and the second main grid portions 112 are staggered and arranged in sequence along the length direction of the back aluminum main grid 11, the width of the first main grid portion 111 is greater than the width of the second main grid portion 112, and the back silver electrode 13 is embedded in the first main grid portion 111. Figure 1As shown, multiple back aluminum main grids 11 extend in the up-down direction and are parallel to each other, and are arranged in parallel at equal intervals in the left-right direction. Each back aluminum main grid 11 includes 6 first main grid portions 111 arranged at equal intervals in the up-down direction, and the 6 first main grid portions 111 are connected as a whole through the second main grid portion 112. The back silver electrodes 13 in the first main grid portions 111 of the multiple back aluminum main grids 11 are arranged corresponding to each other and arranged linearly in the left-right direction to facilitate welding of photovoltaic welding strips. The wide and thin back aluminum main grid designs reduce the aluminum paste consumption and the shading area, thereby improving the conversion efficiency of the back of the battery.

[0027] like Figure 2 As shown, a gap 130 is formed between the back silver electrode 13 and the first main grid portion 111. That is, when printing the paste, there is a certain gap between the aluminum paste and the silver paste. The gap 130 is located on both sides of the length direction of the back silver electrode 13. A gap is reserved between the back silver electrode 13 and the back aluminum main grid 11 along the welding strip direction, which is conducive to the welding of the battery and the photovoltaic welding strip, reduces the hidden cracks of the battery, and prevents the virtual welding and the hidden cracks of the silicon wafer due to the height difference.

[0028] like Figure 3 As shown, the outer surface of the first main grid portion 111 protrudes outward relative to the outer surface of the back silver electrode 13, and a window 1110 is provided on the first main grid portion 111 to expose the back silver electrode 13, and the width of the window 1110 is smaller than the width of the back silver electrode 13. The back silver electrode 13 is mainly used for component welding, and the width of the back silver electrode 13 is 1.6~2.0mm, which reduces or eliminates the risk of unqualified component welding tension. The width of the window 1110 is 1.5~1.8mm. The width of the second main grid portion 112 is 0.1~1.5mm.

[0029] In addition, if Figure 1 As shown, a laser positioning hole 113 is provided on the solar cell. Specifically, there is a laser positioning hole 113 at each end of two back aluminum main grids 11 (the two back aluminum main grids 11 on the leftmost and rightmost sides) located at the edge of the solar cell. That is, there are four laser positioning holes 113, which are located at the four corners of the solar cell, respectively, with a diameter of 0.3-0.6 mm, and are mainly used for the alignment of the aluminum back field and the laser slotting line.

[0030] The double-sided crystalline silicon solar cell of the present invention has the following characteristics: by adopting a back passivation film 2 with a smaller thickness, the appearance of the back printing pattern is improved, thereby achieving a better appearance design and improving the back conversion efficiency; the back passivation film 2 (aluminum oxide and silicon nitride film) has a thickness range of 60-90nm, thereby realizing the back blue film design; the back grid line printing adopts a traditional screen printing aluminum back field machine, without adding additional equipment, reducing the manufacturing cost. In addition, it also has the advantages of reducing the shading area and reducing the aluminum paste consumption.

[0031] The above embodiment is only for illustrating the technical concept and features of the present invention, and is a preferred embodiment. Its purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and it cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A double-sided crystalline silicon solar cell, comprising a silicon substrate, a back passivation film and a back electrode, wherein the back passivation film is laminated on the back of the silicon substrate, characterized in that: The back passivation film is a blue film with a thickness of 60-90 nm, the back electrode comprises a back silver electrode in contact with the silicon substrate, a back aluminum main grid and a plurality of back aluminum sub-grids formed on the back passivation film, the back aluminum sub-grids intersect with the back aluminum main grid, and the back silver electrode is embedded in the back aluminum main grid; The back aluminum main grid includes a plurality of first main grid portions and a plurality of second main grid portions, wherein the first main grid portions and the second main grid portions are staggered and sequentially arranged along the length direction of the back aluminum main grid, the width of the first main grid portion is greater than the width of the second main grid portion, and the back silver electrode is nested in the first main grid portion; A gap is formed between the back silver electrode and the first main grid portion; The outer surface of the first main grid portion protrudes outward relative to the outer surface of the back silver electrode. A window is opened on the first main grid portion to expose the back silver electrode. The back silver electrode is used for component welding. The width of the back silver electrode is 1.6~2.0mm, the width of the window is 1.5~1.8mm, and the width of the second main grid portion is 0.1~1.5mm.

2. The double-sided crystalline silicon solar cell according to claim 1, characterized in that: The solar cell sheet is provided with a laser positioning hole.

3. The double-sided crystalline silicon solar cell according to claim 2, characterized in that: A plurality of the back aluminum main grids are arranged in parallel, and a laser positioning hole is respectively provided at the two ends of two back aluminum main grids located at the edge of the solar cell sheet.

4. The double-sided crystalline silicon solar cell according to claim 1, characterized in that: The back passivation film is aluminum oxide and silicon nitride film.

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