PERC solar cell

Abstract

The utility model provides a PERC solar cell. The PERC solar cell comprises a silicon substrate, a back electrode structure is arranged on the back face of the silicon substrate, the back electrode structure comprises a grid line electrode and a back silver electrode, the grid line electrode comprises a plurality of aluminum auxiliary grids arranged in the first direction and a plurality of aluminum main grids perpendicular to the aluminum auxiliary grids, and each aluminum main grid comprises a thick grid part; the back silver electrode is arranged on the thick grid part, the back silver electrode comprises a silver antenna, the back silver electrode is electrically connected with the aluminum main grid through the silver antenna, and a hollow part is arranged on the back silver electrode. According to the utility model, the hollow structure is arranged on the back silver electrode, so that the consumption of silver paste is reduced, the sintering area of the silver paste is reduced, defects formed on a silicon wafer are reduced, the conversion efficiency of the solar cell is improved, and the cost of the solar cell is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of solar cells, in particular to a PERC solar cell. Background Art

[0002] Solar cells are a clean, green and safe energy source, playing an increasingly important role in replacing traditional fossil energy. In the prior art, PERC (Passivated Emitter and Rear Contact Cell) solar cells have become the main product of solar cells due to their high conversion efficiency and low process cost. PERC solar cells use back passivation and local contact structure, and have very low back recombination on the back of the cell substrate, so they have high open circuit voltage. At the same time, their back has good infrared reflection performance, which can increase short circuit current.

[0003] Figure 1 and Figure 2 FIG. 4 shows the back structure of a PERC solar cell in the prior art. Figure 1 As shown, the back side of the PERC solar cell includes a plurality of aluminum auxiliary grids 1' arranged along a first direction and a plurality of aluminum main grids 2' arranged along a second direction, and the first direction is perpendicular to the second direction. Figure 2 As shown, the back of the PERC solar cell also includes a back silver electrode 3', which is connected to the aluminum main grid 2' by surface overlap. The aluminum main grid 2' and the aluminum auxiliary grid 1' mainly collect carriers on the back of the cell, and then conduct current through the back silver electrode 3'.

[0004] The aluminum main grid 2' and the back silver electrode 3' are prepared by screen printing paste technology. Due to the difference in paste between the back silver electrode 3' and the aluminum main grid 2', the resistivity of this area after sintering is 2 to 5 times that of the pure aluminum electrode, causing the silicon wafer surface to recombine, thereby affecting the conversion efficiency of the solar cell. At the same time, the aluminum paste diffuses into the silver electrode area, affecting the welding and conductivity of the silver electrode; and the silver paste is highly corrosive and can directly burn through the silicon wafer, thereby causing the opening pressure and filling loss of the cell, affecting the cell efficiency. Utility Model Content

[0005] In view of the problems in the prior art, the purpose of the utility model is to provide a PERC solar cell to reduce the sintering area of ​​silver paste, reduce the formation of defects on silicon wafers, and improve the conversion efficiency of the solar cell.

[0006] The utility model provides a PERC solar cell, comprising: a silicon substrate; a back electrode structure is provided on the back of the silicon substrate, and the back electrode structure comprises a grid line electrode and a back silver electrode; wherein:

[0007] A gate line electrode, the gate line electrode comprising a plurality of aluminum sub-grids arranged along a first direction, and a plurality of aluminum main grids arranged perpendicular to the aluminum sub-grids, each of the aluminum main grids comprising a coarse grid portion;

[0008] A back silver electrode is disposed on the rough grid portion, the back silver electrode comprises a silver antenna, the back silver electrode is electrically connected to the aluminum main grid via the silver antenna, and a hollow portion is provided on the back silver electrode.

[0009] In some embodiments, the length of the hollow portion is 1.5 mm to 1.8 mm, and the width of the hollow portion is 0.8 mm to 1.2 mm.

[0010] In some embodiments, the length of the back silver electrode is 2 mm to 2.2 mm, and the width of the back silver electrode is 1 mm to 1.5 mm.

[0011] In some embodiments, the length of the silver antenna is 0.1 mm to 0.15 mm.

[0012] In some embodiments, the length of the structure where the aluminum main grid contacts the back silver electrode is 0.1 mm to 0.15 mm.

[0013] In some embodiments, each of the aluminum main grids includes two sub-main grids that are spaced apart from each other.

[0014] In some embodiments, the distance between the two sub-busbars in the same aluminum busbar is 1.3 mm to 1.5 mm.

[0015] In some embodiments, the number of the aluminum main grids is 9 to 12.

[0016] In some embodiments, the number of the back silver electrodes disposed on each of the aluminum main grids is 4 to 7.

[0017] In some embodiments, a passivation layer is further provided on the back side of the silicon substrate and is disposed on the side of the back electrode structure close to the silicon substrate; a doping layer, an anti-reflection film and a positive electrode are sequentially stacked on the front side of the silicon substrate.

[0018] The PERC solar cell provided by the utility model has the following advantages:

[0019] The PERC solar cell provided by the utility model comprises a silicon substrate, a back electrode structure is provided on the back of the silicon substrate, the back electrode structure comprises a grid line electrode and a back silver electrode, the grid line electrode comprises a plurality of aluminum sub-grids arranged along a first direction, and a plurality of aluminum main grids arranged perpendicularly to the aluminum sub-grids, each of the aluminum main grids comprises a coarse grid portion; the back silver electrode is placed on the coarse grid portion, the back silver electrode comprises a silver antenna, the back silver electrode is electrically connected to the aluminum main grid through the silver antenna, and a hollow portion is provided on the back silver electrode. The utility model reduces the amount of silver paste used, reduces the cost of the solar cell, reduces the sintering area of ​​the silver paste, thereby reducing the defects formed on the silicon wafer, and improves the conversion efficiency of the solar cell by arranging a hollow structure on the back silver electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Other features, objectives and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings.

[0021] Figure 1 It is a schematic diagram of a grid line electrode of a back electrode structure of a PERC solar cell in the prior art;

[0022] Figure 2 It is a schematic diagram of the connection between the aluminum main grid and the back silver electrode of a PERC solar cell in the prior art;

[0023] Figure 3 This is a schematic diagram of the connection between the aluminum main grid and the back silver electrode of a PERC solar cell according to an embodiment of the utility model;

[0024] Figure 4 It is an enlarged schematic diagram of the back silver electrode of an embodiment of the utility model.

[0025] Reference numerals:

[0026] 1' Length of the hollow portion of the aluminum auxiliary grid a1 in the prior art

[0027] 2' Width of the hollow portion of the aluminum main grid a2 in the prior art

[0028] 2 Aluminum main grid b1 Length of back silver electrode

[0029] 21 Sub-busbar b2 Width of back silver electrode

[0030] 2a The length of the back silver antenna of the rough gate c1

[0031] 3 Back silver electrode d The distance between two sub-busbars

[0032] 31 Silver Tentacles

[0033] 32 Hollow DETAILED DESCRIPTION

[0034] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the present invention will be comprehensive and complete and fully convey the concepts of the example embodiments to those skilled in the art. In the figures, the same reference numerals represent the same or similar structures, and thus their repeated description will be omitted. "or" and "or" in the specification may both mean "and" or "or".

[0035] In the representations of the present application, the representations with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics represented in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. Moreover, the represented specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples represented in the present application and the features of the different embodiments or examples, unless they contradict each other.

[0036] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the representation of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0037] In order to solve the problem in the prior art that the large silver paste sintering area in the back electrode structure of PERC solar cells leads to increased cell defects, thereby affecting the photoelectric conversion efficiency of the solar cell, an embodiment of the present application provides a PERC solar cell.

[0038] Figure 3 A schematic diagram showing the connection between the grid line electrode and the back silver electrode of a PERC solar cell according to an embodiment of the utility model is shown; Figure 4 An enlarged view of the back silver electrode of a PERC solar cell according to an embodiment of the utility model is shown; Figure 1 The schematic diagram of the grid line electrode of the back electrode structure of the prior art PERC solar cell shown in FIG. 1 can be used in this embodiment. Figure 1 , Figure 3 and Figure 4It can be seen that the PERC solar cell includes a silicon substrate, and a back electrode structure is provided on the back of the silicon substrate, and the back electrode structure includes a grid line electrode and a back silver electrode 3, and the grid line electrode includes a plurality of aluminum sub-grids arranged along a first direction and a plurality of aluminum main grids 2 arranged perpendicular to the aluminum sub-grids, and each of the aluminum main grids 2 includes a rough grid portion 2a; the back silver electrode 3 is placed on the rough grid portion 2a, and the back silver electrode 3 includes a silver antenna 31, and the back silver electrode 3 is electrically connected to the aluminum main grid 2 through the silver antenna 31, and a hollow portion 32 is provided on the back silver electrode 3. It should be noted that the first direction here is the left-right direction along the paper surface. The back side here is relative to the direction toward the sunlight, and the side facing away from the sunlight is called the back side.

[0039] By setting a hollow portion on the back silver electrode, the sintering area of ​​the silver paste is reduced, the burn-through area is reduced, the formation of solar cell defects is reduced, the recombination of solar cells is reduced, and the conversion efficiency of solar cells is improved; the design of the hollow electrode on the back silver electrode can also reduce the amount of silver paste on the back and reduce the cost of solar cells; the hollow portion is set on the back silver electrode, and only the screen pattern during screen printing needs to be changed, with fewer changing steps and less changes in the process flow, which is conducive to large-scale promotion.

[0040] Specifically, in some embodiments, the length a1 of the hollow portion 32 is 1.5mm to 1.8mm, and may be 1.55mm, 1.6mm, 1.65mm, 1.7mm, 1.75mm, but not limited thereto. The width a2 of the hollow portion is 0.8mm to 1.2mm, and may be 0.9mm, 1.0mm, 1.1mm, but not limited thereto. In this embodiment, a hollow portion 32 is provided on the back silver electrode 3, which can reduce the amount of silver paste on the back electrode structure of the PERC cell. The hollow portion pattern of the back silver electrode 3 is not limited to the hollow structure provided in the present application. In some other embodiments, it may also be a hollow pattern of other structures, such as connected circular hollow patterns, connected square hollow patterns, connected diamond hollow structures, etc., and those skilled in the art may set it according to actual needs.

[0041] In some embodiments, the length b1 of the back silver electrode 3 is 2 mm to 2.2 mm, and may be 2.05 mm, 2.1 mm, or 2.15 mm, but is not limited thereto. The width of the back silver electrode 3 is 1 mm to 1.5 mm, and may be 1.1 mm, 1.2 mm, 1.3 mm, or 1.4 mm, but is not limited thereto.

[0042] In some embodiments, the length c1 of the silver antenna 31 is 0.1 mm to 0.15 mm, and can be 0.11 mm, 0.12 mm, 0.13 mm, or 0.14 mm, but is not limited thereto. The aluminum main grid 2 can realize effective current collection, while increasing the contact area with the solder strip in the later stage and improving the welding tension; the back silver electrode 3 is mainly provided with a connection point with the solder strip in the later stage. Through the aluminum main grid and the back silver electrode, the effects of carrier convergence, current extraction, and stable welding with the solder strip can be achieved. In a preferred embodiment, an aluminum sub-grid located at the top of the back silver electrode 3 and an aluminum sub-grid located at the bottom of the back silver electrode 3 can be set to a disconnected structure to facilitate the welding of the back silver electrode 3 with the component solder strip.

[0043] In some embodiments, the length of the structure where the aluminum main grid 2 contacts the back silver electrode 3 is 0.1 mm to 0.15 mm, and can be 0.11 mm, 0.12 mm, 0.13 mm, or 0.14 mm, but is not limited thereto. The silver feeler 31 is provided on the back silver electrode 3 to overlap the edge of the aluminum main grid 2, mainly to reduce the amount of aluminum paste diffused onto the back silver electrode 3 and improve the welding and conductivity of the back silver electrode 3.

[0044] Please continue reading Figure 3 In this embodiment, each of the aluminum main grids 2 includes two spaced-apart sub-main grids 21. The spacing d between the two sub-main grids 21 in the same aluminum main grid 2 is 1.3 mm to 1.5 mm, and can be 1.32 mm, 1.34 mm, 1.36 mm, 1.38 mm, 1.4 mm, 1.42 mm, 1.44 mm, 1.46 mm, or 1.48 mm, but is not limited thereto.

[0045] In some embodiments, the number of the aluminum main grids 2 is 9 to 12; the number of the back silver electrodes 3 disposed on each of the aluminum main grids 2 is 4 to 7.

[0046] The PERC solar cell provided in the embodiment of the present application has a passivation layer on the back side of the silicon substrate, which is disposed on the side of the back electrode structure close to the silicon substrate; the front side of the silicon substrate is stacked with a doping layer, an anti-reflection film and a positive electrode in sequence. The front side here refers to the direction relative to the direction facing the sunlight, and the side facing the sunlight is called the front side.

[0047] In some embodiments, the passivation layer may be a silicon oxide, aluminum oxide film, etc., and may be prepared by magnetron reactive sputtering, chemical vapor deposition, atomic layer deposition, ion beam deposition, etc.

[0048] In some embodiments, it can be a single layer or multilayer silicon nitride film with a high refractive index, which increases the transmission of light, reduces the reflection of sunlight, and reduces light reflection, thereby increasing the photoelectric conversion efficiency of the battery. The anti-reflection layer can be prepared by plasma chemical vapor deposition, atomic layer deposition and other processes.

[0049] The PERC solar cell provided by the utility model has the following advantages:

[0050] The PERC solar cell includes a silicon substrate, a back electrode structure is provided on the back of the silicon substrate, the back electrode structure includes a grid electrode and a back silver electrode, the grid electrode includes a plurality of aluminum sub-grids arranged along a first direction, and a plurality of aluminum main grids arranged perpendicular to the aluminum sub-grids, each of the aluminum main grids includes a coarse grid portion; the back silver electrode is placed in the coarse grid portion, the back silver electrode includes a silver antenna, the back silver electrode is electrically connected to the aluminum main grid through the silver antenna, and a hollow portion is provided on the back silver electrode. The utility model reduces the amount of silver paste used, reduces the sintering area of ​​the silver paste, reduces the defects formed on the silicon wafer, improves the conversion efficiency of the solar cell, and reduces the cost of the solar cell by providing a hollow structure on the back silver electrode; when printing the back silver electrode with a hollow structure, only the pattern of the printing screen needs to be changed, the process change is small, and it is convenient to promote the change of the back silver structure on a large scale.

[0051] The above contents are further detailed descriptions of the present invention in combination with specific preferred implementations, and the specific implementation of the present invention cannot be considered to be limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A PERC solar cell, characterized in that: include: Silicon substrate; The back side of the silicon substrate is provided with a back electrode structure, and the back electrode structure includes a gate line electrode and a back silver electrode; wherein, The gate line electrode comprises a plurality of aluminum auxiliary grids arranged along a first direction, and a plurality of aluminum main grids arranged perpendicular to the aluminum auxiliary grids, and each of the aluminum main grids comprises a coarse grid portion; The back silver electrode is disposed on the rough grid portion, the back silver electrode comprises a silver antenna, the back silver electrode is electrically connected to the aluminum main grid via the silver antenna, and a hollow portion is provided on the back silver electrode.

2. The PERC solar cell according to claim 1, characterized in that: The length of the hollow portion is 1.5 mm to 1.8 mm, and the width of the hollow portion is 0.8 mm to 1.2 mm.

3. The PERC solar cell according to claim 1, characterized in that The length of the back silver electrode is 2 mm to 2.2 mm, and the width of the back silver electrode is 1 mm to 1.5 mm.

4. The PERC solar cell according to claim 1, characterized in that: The length of the silver antenna is 0.1 mm to 0.15 mm.

5. The PERC solar cell according to claim 1, characterized in that: The length of the structure where the aluminum main grid contacts the back silver electrode is 0.1 mm to 0.15 mm.

6. The PERC solar cell according to claim 1, characterized in that: Each of the aluminum main grids includes two sub-main grids that are spaced apart.

7. The PERC solar cell according to claim 6, characterized in that: The distance between two sub-main grids in the same aluminum main grid is 1.3 mm to 1.5 mm.

8. The PERC solar cell according to claim 1, characterized in that: The number of the aluminum main grids is 9 to 12.

9. The PERC solar cell according to claim 1, characterized in that: The number of the back silver electrodes arranged on each of the aluminum main grids is 4 to 7.

10. The PERC solar cell according to claim 1, characterized in that: A passivation layer is also provided on the back side of the silicon substrate and is disposed on the side of the back electrode structure close to the silicon substrate; a doping layer, an anti-reflection film and a positive electrode are sequentially stacked on the front side of the silicon substrate.

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