Silicon-based solar cell and photovoltaic module

Abstract

The utility model discloses a silicon-based solar cell and a photovoltaic assembly. The silicon-based solar cell comprises a silicon substrate, a functional layer stacked on the silicon substrate, first electric connecting pieces, second electric connecting pieces and a conductive film layer, and the first electric connecting pieces and the second electric connecting pieces are alternately arranged in the first direction of the main surface of the functional layer; the conductive film layer is electrically connected with the first electric connecting piece and the second electric connecting piece, and the size of the first electric connecting piece is different from that of the second electric connecting piece. According to the silicon-based solar cell, the cost of the metal electrode of the silicon-based solar cell can be effectively reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of silicon-based solar cell and photovoltaic module. BACKGROUND

[0002] At present, the metal electrode of silicon-based solar cell is generally made by slurry printing process, drying process and high-temperature sintering process, and the metal electrode of the silicon-based solar cell is generally made of one kind of slurry. There is no effective way to control the cost of the metal electrode of the silicon-based solar cell, so the cost of the silicon-based solar cell still has certain room for reduction. SUMMARY

[0003] Therefore, the utility model provides a kind of silicon-based solar cell and photovoltaic module, which can effectively reduce the cost of the metal electrode of the silicon-based solar cell, so as to achieve the purpose of reducing the cost of the silicon-based solar cell.

[0004] To solve the above technical problems, the utility model provides the following technical solutions:

[0005] In the first aspect, the utility model embodiment provides a kind of silicon-based solar cell, comprising: silicon base, function layer, first electric connecting piece, second electric connecting piece and conductive film layer which are stacked on the silicon base, wherein,

[0006] The first electric connecting piece and the second electric connecting piece are arranged alternately in the first direction of the main surface of the function layer;

[0007] The conductive film layer is electrically connected with the first electric connecting piece and the second electric connecting piece;

[0008] The volume of the first electric connecting piece is different from the volume of the second electric connecting piece.

[0009] In the second aspect, the utility model embodiment provides a kind of photovoltaic module, comprising: a plurality of cell pieces are connected into cell string, wherein,

[0010] The cell piece is cut from the silicon-based solar cell of the first aspect embodiment or the cell piece is the silicon-based solar cell of the first aspect embodiment.

[0011] The technical scheme of the first aspect of the above utility model has the following advantages or beneficial effects:

[0012] The technical scheme provided by the embodiment of the utility model discloses a functional layer on the silicon-based solar cell, respectively through the first electric connecting piece and the second electric connecting piece of different volume of the alternate arrangement, and through the conductive film layer laser welding on the first electric connecting piece and the second electric connecting piece of alternate arrangement, form the electrode of silicon-based solar cell, through the introduction first electric connecting piece and the second electric connecting piece of different volume, can effectively reduce the cost of silicon-based solar cell's metal electrode, thereby reach the purpose of reducing the cost of silicon-based solar cell. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 It is the cross section structure schematic diagram of silicon-based solar cell according to the embodiment of the utility model,

[0014] Figure 2 It is the main flow schematic diagram of preparation method of silicon-based solar cell according to the embodiment provided by the utility model,

[0015] Figure 3 It is the structure schematic diagram of first slurry screen plate according to the embodiment provided by the utility model,

[0016] Figure 4 It is the structure schematic diagram of second slurry screen plate according to the embodiment provided by the utility model,

[0017] Figure 5 It is the structure schematic diagram of the first conductive slurry that silicon is printed out on the functional layer of silicon-based solar cell according to the embodiment of the utility model through the first slurry screen plate,

[0018] Figure 6 It is the relative position relation schematic diagram of printed first conductive slurry and second conductive slurry according to the embodiment provided by the utility model,

[0019] Figure 7 It is the first relative position relation of first electric connecting piece 31 and second electric connecting piece 32 according to the embodiment of the utility model,

[0020] Figure 8 It is the second relative position relation of first electric connecting piece 31 and second electric connecting piece 32 according to the embodiment of the utility model,

[0021] Figure 9 It is the third relative position relation of first electric connecting piece 31 and second electric connecting piece 32 according to the embodiment of the utility model.

[0022] Reference signs:

[0023] 001 - first printed plate; 002 - second printed plate; 10 - silicon substrate; 20 - functional layer; 21 - tunneling oxide layer; 22 - doped polysilicon layer; 23 - passivation anti-reflection layer; 31 - first electrical connecting member; 31 '- first conductive paste; 32 - second electrical connecting member; 32 '- second conductive paste; 33 - conductive film layer; 34 - electrical connecting area. DETAILED DESCRIPTION

[0024] The existing high-efficiency silicon-based solar cells such as Topcon, BC, etc. all need to use high-temperature paste to prepare conductive metal electrodes after sintering. The composition of the general high-temperature sintering type conductive paste is complex: it contains not only organic substances to make the paste have good screen printing performance, but also glass frits to corrode the surface dielectric film layer of the cell to make the paste have relatively firm adhesion, and also contains metal particles with electrical conductivity. For crystalline silicon photovoltaic cells, the paste needs to be dried and rapidly sintered after printing to complete the preparation of the electrode. After sintering, most of the organic substances disappear due to volatilization and oxidation, and most of the glass and metal particles remain to form a conductive metal electrode.

[0025] The solid content in the conductive paste plays an important role in the performance of the metal electrode formed by it. On the one hand, a higher solid content makes the electrode have better adhesion, which can ensure the tensile strength requirement of the electrode; on the other hand, a higher solid content can also ensure that the electrode has good electrical conductivity. However, the conductive metal particles such as silver particles in the conductive paste are precious metals with high cost, and the rare metal elements in the glass also belong to materials with high cost; thus, the conductive paste with high solid content has high cost, which is not conducive to reducing the price of crystalline silicon solar cell production.

[0026] In order to solve the problem that the existing silicon-based solar cell consumes a relatively high amount of high-solid-content conductive paste, the embodiments of the present application provide a novel silicon-based solar cell.

[0027] Among them, Figure 1 A cross-sectional structure schematic diagram of the silicon-based solar cell provided by the embodiments of the present application is shown. As shown in the figure, Figure 1 The silicon-based solar cell can include: a silicon substrate 10, a functional layer 20 stacked on the silicon substrate 10, a first electrical connecting member 31, a second electrical connecting member 32, and a conductive film layer 33, wherein,

[0028] The first electrical connecting member 31 and the second electrical connecting member 32 are alternately arranged in a first direction of a main surface of the functional layer 20; the conductive film layer 33 is electrically connected with the first electrical connecting member 31 and the second electrical connecting member 32; wherein the volume of the first electrical connecting member 31 is different from the volume of the second electrical connecting member 32.

[0029] The silicon-based solar cell can be any one of a TOPCon cell, a BC cell, an HJT cell, etc. Specifically, the silicon-based solar cell comprises a silicon substrate 10 and a functional layer 20 arranged on one or both main surfaces of the silicon substrate 10. The functional layer 20 can be a single-layer structure or a stacked structure. For the single-layer structure, the functional layer 20 generally refers to a doped layer containing N-type or P-type doping elements formed on the main surface of the silicon substrate 10 (the doped layer can be formed by diffusing doping elements on the main surface of the silicon substrate 10). For the stacked structure, the functional layer 20 can be a plurality of doped layers stacked on the main surface of the silicon substrate 10 (each doped layer contains the same doping elements such as N-type or P-type doping elements). In addition, the functional layer 20 of the stacked structure can also be a general term of a plurality of functional film layers stacked together. For example, as shown in FIG. 1, the functional layer 20 of the stacked structure can be a general term of a tunneling oxide layer 21, a doped polysilicon layer 22, and a passivation anti-reflection layer 23 stacked in order from inside to outside on the main surface of the silicon substrate 10. For another example, the functional layer 20 of the stacked structure can also be a general term of an intrinsic silicon-containing film layer, a doping element-containing silicon-containing film layer, a passivation layer, and an anti-reflection layer stacked in order from inside to outside on the main surface of the silicon substrate 10. For another example, the functional layer 20 of the stacked structure can also be a general term of an intrinsic amorphous silicon passivation layer, a doped amorphous silicon layer, and a transparent conductive film layer (which can be an ITO conductive film layer or an FTO conductive film layer) stacked in order from inside to outside on the main surface of the silicon substrate 10. The ITO (Indium Tin Oxide) mainly contains indium oxide (In2O3) and tin oxide (SnO2), and the FTO (Fluorine-doped Tin Oxide) is a material in which fluorine elements are doped in tin oxide (SnO2) to enhance the conductivity. The functional layer 20 can be a functional layer 20 on the light-receiving surface and / or the back surface of the silicon-based solar cell. Preferably, the functional layer 20 is a functional layer 20 on the back surface of the silicon-based solar cell. Figure 1

[0030] More specifically, for the silicon-based solar cell being a TOPCon cell, the functional layer 20 is a stacked structure composed of a tunneling oxide layer 21, a doped polysilicon layer 22, and a passivation anti-reflection layer 23 arranged in order on the back surface of the silicon substrate 10.

[0031] ​In addition, the back surface of the silicon substrate 10 is provided with n-type regions and p-type regions which are spaced and alternately distributed, the functional layer 20 located in the n-type region is a laminated structure composed of a first tunneling oxide layer, an n-type doped silicon layer and a first passivation layer which are sequentially arranged on the back surface of the silicon substrate 10, and the functional layer 20 located in the p-type region is a laminated structure composed of a second tunneling oxide layer, a p-type doped silicon layer and a second passivation layer which are sequentially arranged on the back surface of the silicon substrate 10.

[0032] It can be understood that the first electric connection 31 and the second electric connection 32 with different volumes can be formed by selecting conductive pastes with different solid contents. That is, in the case of printing the same volume, the electric connection formed by sintering the conductive paste with different solid contents has different volumes. The higher the solid content of the conductive paste, the larger the volume of the electric connection formed by sintering. Taking the case of printing and sintering the first conductive paste 31' to form the first electric connection 31 and printing and sintering the second conductive paste 32' to form the second electric connection 32 (the solid content of the first conductive paste 31' is different from that of the second conductive paste 32') as an example, in the case of the same volume of the printed first conductive paste 31' and the second conductive paste 32', the first electric connection 31 and the second electric connection 32 formed by the first conductive paste 31' and the second conductive paste 32' with different solid contents have different volumes. In the case that the solid content of the first conductive paste 31' is greater than that of the second conductive paste 32' and the printing amount of the first conductive paste 31' is the same as that of the second conductive paste 32', the volume of the first electric connection 31 formed by sintering the first conductive paste 31' is greater than that of the second electric connection 32 formed by sintering the second conductive paste 32'.

[0033] By the different volumes of the first electric connection 31 and the second electric connection 32, the material usage of the electric connection can be reduced, thereby effectively reducing the cost of the silicon-based solar cell.

[0034] In addition, the performance and cost of the conductive pastes with different solid contents are different. Generally speaking, the higher the solid content, the better the conductive performance of the conductive paste, but the higher the cost. Based on this, the technical scheme provided in the embodiments of the present application can effectively reduce the cost of the solar cell by selecting the first conductive paste 31' and the second conductive paste 32' with different solid contents. In order to overcome the problem of the performance difference between the first electric connection 31 and the second electric connection 32 formed by the conductive pastes with different solid contents, the silicon-based solar cell provided in the embodiments of the present application can effectively balance the difference between the performance of the first electric connection 31 and the performance of the second electric connection 32 by introducing the low-cost conductive film layer 33, thereby ensuring that the silicon-based solar cell can stably and evenly lead out the current.

[0035] As described above, the first electric connecting member 31 is generally formed by a first conductive paste 31', and the second electric connecting member 32 is generally formed by a second conductive paste 32', wherein the solid content of the first conductive paste 31' is different from the solid content of the second conductive paste 32'. Exemplarily, the solid content of the first conductive paste 31' is greater than the solid content of the second conductive paste 32'. Generally, the solid content of the conductive paste refers to the ratio of the mass of the materials (such as glass, conductive metal particles and inorganic additives, etc.) remaining after the organic substances in the conductive paste are volatilized after sintering to the mass of the entire paste. The glass in the conductive paste not only firmly bonds to the surface of the silicon wafer, but also firmly binds the metal particles in the electrode.

[0036] Specifically, the percentage of the solid mass of the first conductive paste 31' used to form the first electric connecting member 31 to the mass of the entire paste (i.e. the solid content of the first conductive paste 31') is generally 91% to 97%. For example, the solid content of the first conductive paste 31' can be 91%, 92%, 93%, 94%, 95%, 96% or 97%, etc. The percentage of the solid mass of the second conductive paste 32' used to form the second electric connecting member 32 to the mass of the entire paste (i.e. the solid content of the second conductive paste 32') is generally 60% to 90%. For example, the solid content of the second conductive paste 32' can be 60%, 65%, 68%, 70%, 75%, 80%, 85% or 90%, etc. Preferably, the solid content of the second conductive paste 32' is 60% to 80%. For example, the solid content of the second conductive paste 32' is preferably 60%, 65%, 68%, 70%, 75% or 80%, etc. More preferably, the solid content of the second conductive paste 32' is 60% to 70%. For example, the solid content of the second conductive paste 32' is more preferably 60%, 65%, 68% or 70%, etc.

[0037] As shown in FIG. 1, the first electric connecting member 31 and the second electric connecting member 32 are arranged alternately on the surface of the silicon wafer 10. In other words, the first electric connecting member 31 and the second electric connecting member 32 are arranged in a staggered manner on the surface of the silicon wafer 10. Figures 7 to 9 As shown in FIG. 1, the first electric connecting member 31 and the second electric connecting member 32 are arranged alternately on the surface of the silicon wafer 10. In other words, the first electric connecting member 31 and the second electric connecting member 32 are arranged in a staggered manner on the surface of the silicon wafer 10.

[0038] In addition, the conductive film layer 33 can be a single layer film layer or a laminated composite film layer composed of at least one metal, and specifically, the metal forming the conductive film layer 33 can be any one or more of aluminum, copper, silver, etc., and preferably, the conductive film layer 33 is an aluminum film layer, a copper film layer, or an aluminum-copper alloy film layer. The conductive film layer 33 can be consistent with the shape of the first electrical connecting member 31 and the second electrical connecting member 32. The conductive film layer 33 is generally welded to the first electrical connecting member 31 and the second electrical connecting member 32 by laser. The conductive film layer 33 and the first electrical connecting member 31 and the second electrical connecting member 32 are alternately arranged to balance the carrier transport capacity of each region of the silicon-based solar cell and avoid carrier transport imbalance.

[0039] Further, as shown in FIG. 1, the first electrical connecting member 31 and the second electrical connecting member 32 are alternately arranged in a first direction D1 to form an electrical connecting region 34, and the functional layer 20 has a plurality of electrical connecting regions 34 arranged at intervals in a second direction D2 perpendicular to the first direction D1. Figures 7 to 9 Figures 7 to 9

[0040] Specifically, the first electrical connecting member 31 and the second electrical connecting member 32 of the plurality of electrical connecting regions 34 are electrically connected to the same conductive film layer 33, or each electrical connecting region 34 is connected to a conductive film layer 33, and any two rows of electrical connecting regions 34 are connected to different conductive film layers 33. That is, the electrical connecting region 34 corresponds to the conductive film layer 33 one by one.

[0041] Further, as shown in FIG. 1, the first electrical connecting member 31 and the second electrical connecting member 32 are alternately arranged in a first direction D1 to form an electrical connecting region 34, and the functional layer 20 has a plurality of electrical connecting regions 34 arranged at intervals in a second direction D2 perpendicular to the first direction D1. Figure 1

[0042] ​​​Further, the utility model embodiment further provides a photovoltaic module, the photovoltaval module includes a plurality of cell piece string connection battery string, wherein, cell piece is cut from the silicon based solar cell provided by above -mentioned embodiment or cell piece is the silicon based solar cell provided by above -mentioned embodiment. Specifically, every two adjacent cell piece is connected by the connection between the conductive film layer 33 contained in cell piece. More specifically, for every two adjacent cell piece in battery string, the conductive film layer 33 of one cell piece extending out cell piece is overlapped on the conductive film layer 33 of another cell piece, after the placement of each cell piece on one battery string is completed, the lap position is welded by laser, and the battery string is obtained. The whole process does not need to introduce the welding strip, and the welding strip alignment and laying process is also omitted, which reduces the production cost of photovoltaic module, and improves the production efficiency of photovoltaic module.

[0043] For the silicon based solar cell provided by the above embodiment, as shown in Figure 2 The utility model embodiment provides the preparation method for the above silicon based solar cell can include the following steps:

[0044] Step S201: printing first conductive paste 31' and second conductive paste 32' on the functional layer 20 of the silicon based solar cell, respectively, wherein the solid content of the first conductive paste 31' and the second conductive paste 32' is different and arranged alternately in the first direction of the main surface of the functional layer 20.

[0045] Wherein, the silicon based solar cell can be any kind of solar cell, such as TOPCon cell, BC cell, HJT cell, etc.

[0046] Wherein, the silicon based solar cell generally includes a silicon substrate 10 and a functional layer 20 arranged on one main surface or both main surfaces of the silicon substrate 10. The functional layer 20 can be a single layer structure or a laminated structure. Specifically, for the single layer structure of the functional layer 20, the functional layer 20 generally refers to the doped layer containing N-type or P-type doping elements formed on the main surface of the silicon substrate 10 (the doped layer can be formed by diffusing doping elements on the main surface of the silicon substrate 10). For the laminated structure of the functional layer 20, the functional layer 20 can be a plurality of doped layers (each doped layer contains the same doping element such as N-type or P-type doping element) formed by layering on the main surface of the silicon substrate 10. In addition, the functional layer 20 of the laminated structure can also be a general term for a plurality of functional film layers formed by layering. For example, Figure 9As shown, the functional layer 20 of the laminated structure can be a general term of a tunneling oxide layer 21, a doped polysilicon layer 22 and a passivation anti-reflection layer 23 which are sequentially laminated from inside to outside on the main surface of the silicon substrate 10. For another example, the functional layer 20 of the laminated structure can also be a general term of an intrinsic silicon-containing thin film layer, a doped element-containing silicon-containing thin film layer, a passivation layer and an anti-reflection layer which are sequentially laminated from inside to outside on the main surface of the silicon substrate 10. For still another example, the functional layer 20 of the laminated structure can also be a general term of an intrinsic amorphous silicon passivation layer, a doped amorphous silicon layer and a transparent conductive film layer (which can be an ITO conductive film layer or an FTO conductive film layer) which are sequentially laminated from inside to outside on the main surface of the silicon substrate 10. The ITO (Indium Tin Oxide) is mainly composed of indium oxide (In2O3) and tin oxide (SnO2), and the FTO (Fluorine-doped Tin Oxide) is a material in which fluorine is doped in tin oxide (SnO2) to enhance the conductivity. The functional layer 20 can be a functional layer 20 of a light-receiving surface and / or a back surface of a silicon-based solar cell. Preferably, the functional layer 20 is a functional layer 20 of a back surface of a silicon-based solar cell.

[0047] It is worth noting that the printing of the conductive paste on the functional layer 2 in the embodiments of the present application refers to that the conductive paste is printed on the side of the functional layer 2 away from the silicon substrate 10 (which is the substrate of the silicon-based solar cell), and does not specifically refer to that the electrically connected member formed by the conductive paste during the use of the silicon-based solar cell is located above the functional layer 2. For example, for the above-mentioned functional layer 20 which is a functional layer 20 of a back surface of a silicon-based solar cell, during the printing process, if the functional layer 20 of the back surface of the silicon-based solar cell faces upwards, the first conductive paste 31' and the second conductive paste 32' are located above the functional layer 20 of the back surface of the silicon-based solar cell, and if the functional layer 20 of the back surface of the silicon-based solar cell faces downwards, the first conductive paste 31' and the second conductive paste 32' are located below the functional layer 20 of the back surface of the silicon-based solar cell. For the above-mentioned functional layer 20 which is a functional layer 20 of a light-receiving surface of a silicon-based solar cell, during the printing process, if the functional layer 20 of the light-receiving surface of the silicon-based solar cell faces upwards, the first conductive paste 31' and the second conductive paste 32' are located above the functional layer 20 of the light-receiving surface of the silicon-based solar cell, and if the functional layer 20 of the light-receiving surface of the silicon-based solar cell faces downwards, the first conductive paste 31' and the second conductive paste 32' are located below the functional layer 20 of the light-receiving surface of the silicon-based solar cell.

[0048] Generally speaking, the solid content of the conductive paste refers to the ratio of the material (such as glass body, conductive metal particles and inorganic additives, etc.) remaining after the organic matter in the conductive paste is volatilized after sintering to the mass of the entire paste. Among them, the glass body in the conductive paste not only firmly adheres to the surface of the silicon wafer, but also firmly combines the metal particles in the electrode.

[0049] The performance and cost of conductive pastes with different solid contents are different. Generally speaking, the higher the solid content, the better the conductive performance of the conductive paste, but the higher the cost. Based on this, the technical scheme provided by the embodiments of the present application can effectively reduce the cost of solar cells by selecting first conductive paste 31' and second conductive paste 32' with different solid contents. In order to overcome the problem of performance difference of conductive pastes with different solid contents, the technical scheme provided by the embodiments of the present application introduces a low-cost conductive film layer 33 in the subsequent step, which can effectively balance the difference between the performance of the first electric connecting piece 31 formed by the first conductive paste 31' and the performance of the second electric connecting piece 32 formed by the second conductive paste 32', thereby ensuring that the silicon-based solar cell can stably and evenly lead out current.

[0050] The solid content of the first conductive paste 31' can be higher than that of the second conductive paste 32' or lower than that of the second conductive paste 32'.

[0051] The solid content of the first conductive paste 31' is higher than that of the second conductive paste 32' as an example. That is, the high solid content conductive paste involved in the following technical scheme is the first conductive paste 31', and the low solid content conductive paste involved in the following technical scheme is the second conductive paste 32'. It is worth noting that the high solid content and low solid content involved in the following technical scheme are relative, that is, the solid content of the first conductive paste 31' is greater than that of the second conductive paste 32'.

[0052] Specifically, the solid mass percentage of the first conductive paste 31' used in this step S201 accounts for 91%~97% of the mass of the entire paste (i.e. the solid content of the first conductive paste 31'). For example, the solid content of the first conductive paste 31' can be 91%, 92%, 93%, 94%, 95%, 96% or 97%, etc. The solid mass percentage of the second conductive paste 32' used in this step S101 accounts for 60%~90% of the mass of the entire paste (i.e. the solid content of the second conductive paste 32'). For example, the solid content of the second conductive paste 32' can be 60%, 65%, 68%, 70%, 75%, 80%, 85% or 90%, etc. Preferably, the solid content of the second conductive paste 32' is 60%~80%, for example, the solid content of the second conductive paste 32' is preferably 60%, 65%, 68%, 70%, 75% or 80%, etc. More preferably, the solid content of the second conductive paste 32' is 60%~70%, for example, the solid content of the second conductive paste 32' is more preferably 60%, 65%, 68% or 70%, etc.

[0053] The first direction is generally consistent with the extension direction of the length or the extension direction of the width of the silicon-based solar cell. It is worth noting that for a BC cell, the first direction is generally consistent with the extension direction of the N functional region or the extension direction of the P functional region of the BC cell.

[0054] Specifically, the specific embodiment of step S201 can include: printing the first conductive paste 31' with high solid content by using a first paste screen plate 001 with multiple columns and multiple rows of printing holes, wherein the multiple printing holes of each row of the first paste screen plate 001 are arranged in linear intervals, the printing holes of each row of the first paste screen plate 001 extend along the first direction, the printing holes of each column of the first paste screen plate 001 extend along the second direction of the main surface of the functional layer 20, and the first direction is perpendicular to the second direction; printing the second conductive paste 32' with low solid content by using a second paste screen plate 002 with multiple columns and multiple rows of printing holes, wherein the multiple columns and multiple rows of printing holes of the second paste screen plate 002 correspond one-to-one to the multiple columns and multiple rows of the first paste screen plate 001, and the multiple printing holes of the second paste screen plate 002 and the first paste screen plate 001 belonging to the same row are arranged in a staggered manner.

[0055] It is worth mentioning that there is no strict sequence between the printing of the first conductive paste 31' with high solid content by the first paste screen plate 001 with multiple columns and multiple rows of printing holes and the printing of the second conductive paste 32' with low solid content by the second paste screen plate 002 with multiple columns and multiple rows of printing holes. The first conductive paste 31' can be printed first and then the second conductive paste 32' can be printed, or the second conductive paste 32' can be printed first and then the first conductive paste 31' can be printed. In addition, the first conductive paste 31' can be printed by the second paste screen plate 002, and the second conductive paste 32' can be printed by the first printing paste screen plate 001.

[0056] Exemplarily, the structure of the first paste screen plate 001 and the second paste screen plate 002 are shown in Figure 3 and Figure 4 respectively. The first paste screen plate 001 can include 7 columns of A1, A2, A3, A4, A5, A6 and A7 and 7 rows of B1, B2, B3, B4, B5, B6 and B7 printing holes, and the second paste screen plate 002 also includes 7 columns of A1, A2, A3, A4, A5, A6 and A7 and 7 rows of B1, B2, B3, B4, B5, B6 and B7 printing holes. The structure of the first conductive paste 31' printed on the functional layer 20 of the silicon-based solar cell by the first paste screen plate 001 is shown in Figure 5 . On the basis of Figure 5 , the second conductive paste 32' is further printed by the second paste screen plate 002, and the structure shown in Figure 6 is obtained: on each row, the first conductive paste 31' and the second conductive paste 32' are arranged alternately, and on each column, the first conductive paste 31' and the second conductive paste 32' are also arranged alternately. Through this structure, the amount of the first conductive paste 31' with high solid content can be reduced to effectively control the cost of the conductive paste, thereby reducing the cost of the silicon-based solar cell.

[0057] Further, as shown in Figure 3 , for the first paste screen plate 001, the multiple printing holes of every two adjacent rows are staggered. In addition, the multiple printing holes of every two adjacent columns in the first paste screen plate 001 are also staggered. In addition, for the first paste screen plate 001, the multiple printing holes of each column can be arranged in a linear row.

[0058] Further, as shown in Figure 4 , for the second paste screen plate 002, the multiple printing holes of every two adjacent rows are staggered. Further, the multiple printing holes of every two adjacent columns in the second paste screen plate 002 are also staggered. In addition, for the second paste screen plate 002, the multiple printing holes of each column can be arranged in a linear row.

[0059] It is worth mentioning that, for the printing holes Figure 3and Figure 4 The cross section of the printing hole is only exemplarily given as a rectangular shape. The cross section of the printing hole can also be other shapes such as a circular shape, an elliptical shape, a square shape, etc.

[0060] In addition, Figure 6 The relative positional relationship that the first conductive paste 31' with a high solid content and the second conductive paste 32' with a low solid content are separated is only exemplarily given. In addition, the first conductive paste 31' and the second conductive paste 32' can also overlap or contact each other. That is, the adjacent first conductive paste 31' and the second conductive paste 32' printed in this step can overlap or be connected or be separated. In addition, the height, width or length of the first conductive paste 31' and the second conductive paste 32' printed can be the same or different.

[0061] This step ensures that the conductive structure formed can be firmly combined with the functional layer 20 by using the second conductive paste 32' with a low solid content to replace part of the first conductive paste 31' with a high solid content, and the conductive structure formed has relatively strong tensile force, while the preparation cost of the silicon-based solar cell can be reduced.

[0062] Further, in the above-mentioned sequential two printing processes using the first paste screen plate 001 and the second paste screen plate 002, in order to avoid the damage of the paste screen plate (which can be the first paste screen plate 001 or the second paste screen plate 002) used in the second printing to the conductive paste (which can be the first conductive paste 31' or the second conductive paste 32') printed in the first printing, after the first printing is completed, the conductive paste printed in the first printing is dried first, and then the second printing is performed (understandably, after the first conductive paste 31' is printed in the first printing, the second printing is the second conductive paste 32'; after the second conductive paste 32' is printed in the first printing, the second printing is the first conductive paste 31'). In addition, after the second printing is completed, the conductive paste printed in the second printing can also be dried again to preliminarily solidify the conductive paste.

[0063] In addition, by introducing the second conductive paste 32' with a low solid content, due to the lower mass fraction of silver particles and glass components, the damage to the passivation layer or the passivation anti-reflection layer 23 of the functional layer 20 at the same sintering temperature is reduced, which is beneficial to improve the open circuit voltage of the silicon-based solar cell.

[0064] Step S202: sintering the first conductive paste 31' and the second conductive paste 32', and forming the first electrically connecting member 31 and the second electrically connecting member 32 alternately arranged in the first direction.

[0065] The sintered first conductive paste 31 ′ forms the first electrical connector 31 ; the sintered second conductive paste 32 ′ forms the second electrical connector 32 .

[0066] It can be understood that, while the volumes of the first conductive paste 31' and the second conductive paste 32' printed in step S101 are the same, the different solid contents of the first conductive paste 31' and the second conductive paste 32' result in different volumes of the first electrical connector 31 and the second electrical connector 32 formed by sintering in this step. Specifically, for the same volume of conductive paste, the higher the solid content, the larger the volume of the electrical connector formed after sintering. If the solid content of the first conductive paste 31' is greater than that of the second conductive paste 32', and the printed amount of the first conductive paste 31' and the printed amount of the second conductive paste 32' are the same, the volume of the first electrical connector 31 formed by sintering the first conductive paste 31' is greater than that of the second conductive paste 32'.

[0067] Among them, Figures 7 to 9 As shown in FIG. 3 , the first electrical connectors 31 and the second electrical connectors 32 alternately arranged in the first direction D1 form an electrical connection area 34. Figures 7 to 9 As shown, the first electrical connectors 31 and the second electrical connectors 32 in the same row form an electrical connection area 34. In addition, the electrical connection area 34 may also be formed by multiple rows of first electrical connectors 31 and second electrical connectors 32.

[0068] The relative position relationship between the first electrical connector 31 and the second electrical connector 32 obtained by combining the above steps S201 and S202 is exemplarily shown as follows: Figures 7 to 9 That is, Figures 7 to 9 As shown, the first electrical connector 31 and the second electrical connector 32 are generally arranged alternately in the first direction D1. Figure 7 and Figure 9 As shown, the first electrical connector 31 and the second electrical connector 32 are spaced apart in the first direction D1. Figure 8 As shown, the first electrical connector 31 and the second electrical connector 32 intersect in the first direction D1 (i.e., one end of the adjacent first electrical connector 31 and one end of the second electrical connector 32 in the same row are in contact). In addition, the first electrical connector 31 and the second electrical connector 32 may also partially overlap in the first direction D1.

[0069] Step S203 : laser welding the conductive film layer 33 to the alternately arranged first electrical connectors 31 and second electrical connectors 32 .

[0070] The conductive film layer 33 is arranged alternately with the first electrical connecting member 31 and the second electrical connecting member 32, which can balance the carrier transmission capacity of each area of the silicon-based solar cell and avoid carrier transmission imbalance.

[0071] Specifically, for the case of dividing multiple electrical connecting areas in step S202, step S203 can connect multiple electrical connecting areas 34 to the same conductive film layer 33; or connect each electrical connecting area 34 to one conductive film layer 33, and connect any two electrical connecting areas 34 to different conductive film layers 33. Preferably, each row of alternately arranged first electrical connecting members 31 and second electrical connecting members 32 forms one electrical connecting area 34, and one independent conductive film layer 33 is arranged for one electrical connecting area 34.

[0072] Specifically, the metal forming the conductive film layer 33 can be any one or more of aluminum, copper, silver, etc., and preferably the conductive film layer 33 is an aluminum film layer, a copper film layer, or an aluminum-copper alloy film layer. The conductive film layer 33 can have the same shape as the first electrical connecting member 31 and the second electrical connecting member 32.

[0073] The conductive film layer 33 is welded to the sintered first and second electrical connectors 31 and 32 using a laser welding technique. The laser welding process can be such that the laser is irradiated into the conductive film layer 33 in regions corresponding to the first and second electrical connectors 31 and 32, and the high energy provided by the laser is instantaneously absorbed by the conductive film layer 33 and the first and second electrical connectors 31 and 32, causing the conductive film layer 33 and the surfaces of the first and second electrical connectors 31 and 32 to melt and metallurgically bond, and after cooling, the first and second electrical connectors 31 and 32 are welded to the conductive film layer 33. Alternatively, the laser welding process can be such that the laser is irradiated into the conductive film layer 33 in a region corresponding to either the first or second electrical connector 31 or 32. For the laser irradiation into the region corresponding to the first electrical connector 31, the conductive film layer 33 and the surface of the first electrical connector 31 melt and metallurgically bond, and after cooling, the first electrical connector 31 is welded to the conductive film layer 33, forming a fixed connection between the first electrical connector 31 and the conductive film layer 33. For the laser irradiation into the region corresponding to the second electrical connector 32, the conductive film layer 33 and the surface of the second electrical connector 32 melt and metallurgically bond, and after cooling, the second electrical connector 32 is welded to the conductive film layer 33, forming a fixed connection between the second electrical connector 32 and the conductive film layer 33. Preferably, the laser is simultaneously irradiated into the conductive film layer 33 in regions corresponding to the first and second electrical connectors 31 and 32, causing the conductive film layer 33 to metallurgically bond to the surfaces of the first and second electrical connectors 31 and 32 at the same time.

[0074] In particular, the laser parameters (such as wavelength, energy, duration of action, etc.) selected for the laser welding technique can be determined according to the energy required for melting and metallurgically bonding the first and second electrical connectors 31 and 32 and the conductive film layer 33, and the selected laser parameters are not limited herein.

[0075] In general, the laser beam width used in the laser welding of step S203 is not greater than the width of the first electrical connector 31 and the width of the second electrical connector 32. More specifically, in the process of welding the conductive film layer 33 to the first and second electrical connectors 31 and 32 using the laser welding technique, the area of the laser welding (the area of the pattern scanned by the laser) is not greater than the area of the first and second electrical connectors 31 and 32, and the pattern of the laser welding can be designed to be any shape.

[0076] Further, as Figure 1The cross-sectional schematic view of the structure formed after the step is shown, and the length of the conductive film layer 33 in the first direction is greater than the length of the silicon substrate 10 of the silicon-based solar cell in the first direction. Through this design, the conductive film layer 33 replaces the solder strip for series connection of the cell pieces in the photovoltaic module, that is, the solar cell is divided into half-cell pieces, and the conductive film layer of one cell piece is extended to overlap the conductive film layer 33 of the adjacent cell piece, thereby realizing series connection between the cell pieces, reducing the production cost of the photovoltaic module, omitting the solder strip alignment and solder strip welding process in the production process of the photovoltaic module, and improving the production efficiency of the photovoltaic module.

[0077] By printing the first conductive paste 31' and the second conductive paste 32' with different solid contents on the functional layer 20 of the silicon-based solar cell, respectively (for example, the first conductive paste 31' with high solid content and the second conductive paste 32' with low solid content), the first conductive paste 31' and the second conductive paste 32' with different solid contents are sintered to form the first electrically conductive component 31 and the second electrically conductive component 32 arranged alternately, and the conductive film layer 33 is laser welded on the first electrically conductive component 31 and the second electrically conductive component 32 arranged alternately to form the electrode of the silicon-based solar cell. The first conductive paste 31' and the second conductive paste 32' with different solid contents have different costs, and the first conductive paste 31' and the second conductive paste 32' with different solid contents and the low-cost conductive film layer 33 can effectively reduce the cost of the metal electrode of the silicon-based solar cell, thereby achieving the purpose of reducing the cost of the silicon-based solar cell.

[0078] More preferably, the technical scheme provided by the embodiment of the utility model is directed to the preparation of the conductive structure on the back surface of the Topcon cell or the BC cell to replace the electrode on the back surface of the existing Topcon cell or the BC cell, thereby reducing the preparation cost of the high-efficiency cell while maintaining the cell efficiency.

[0079] In addition, in the structure obtained by the above preparation method, the first electrically conductive component 31 formed by the first conductive paste with high solid content has good adhesion, which can ensure firm combination of the conductive paste and the silicon wafer, and also ensure firm combination between the conductive film layer 33 and the welding point of the conductive electrode, thereby ensuring the comprehensive tensile requirement of the electrode. The second electrically conductive component 32 formed by the second conductive paste with low solid content has excellent charge conduction ability, thereby ensuring the conductive ability of the solar cell. In addition, the introduction of the conductive film layer 33 can also balance the flow difference between the first electrically conductive component 31 and the second electrically conductive component 32, thereby ensuring that the silicon-based solar cell can stably transmit current.

[0080] Embodiment one

[0081] Preparation method for Topcon cell:

[0082] A, select the resistivity of 2.5 Ω•cm single crystal N-type silicon wafer.

[0083] B, select the mass fraction of 4% sodium hydroxide solution for silicon wafer anisotropic etching, get the surface of the silicon wafer, its reflectivity is 11.8%.

[0084] C, silicon wafer back surface high temperature boron diffusion preparation PN junction.

[0085] D, using wet single side etching equipment for silicon wafer back boron doped area etching removal, while retaining the front boron silicon glass layer.

[0086] E, using furnace tube thermal oxidation method in silicon wafer back surface growth thickness of 1.8 nm of tunnel oxide layer, and in the furnace tube into SiH4 gas preparation 80 nm of poly silicon layer.

[0087] F, using high temperature furnace tube for back poly silicon layer phosphorus doping, wherein the active phosphorus in poly silicon layer concentration reaches 4E20cm -3 .

[0088] G, using wet equipment to remove the silicon wafer front and back boron silicon glass layer and phosphorus silicon glass layer, while cleaning the front of the silicon wafer around the poly silicon layer.

[0089] H, front deposition of 4 nm aluminum oxide passivation silicon wafer surface.

[0090] I, in the surface of the aluminum oxide film deposition 78 nm silicon nitride film, in the back of the doped poly silicon surface deposition 80 nm silicon nitride film.

[0091] J, in the battery surface using screen printing technology to set up continuous solid content of 93% conductive silver paste and drying.

[0092] K, using screen printing technology in the battery back surface set up intermittent solid content of 93% conductive silver paste and drying, and then using screen printing technology in the battery back surface set up intermittent solid content of 70% conductive silver paste, and high, low solid content of conductive silver paste for alternative arrangement, such as Figure 5 shown. After rapid sintering in high temperature sintering furnace, the preparation of the first and second electrical connection of the back surface of Topcon cell is completed.

[0093] L, provide conductive aluminum film, set the width of the aluminum film close to the width of each row of printed first and second electrical connection, cover the aluminum film on the surface of the first and second electrical connection.

[0094] M, using laser technology to weld the aluminum film to the first and second electrical connection respectively, complete the preparation of Topcon cell.

[0095] Example Two

[0096] The present example provides a method for preparing a BC cell, the steps of which are as follows:

[0097] The BC cell structure before printing the electrode is prepared using existing processes, which will not be described here. Among them, the back surface of the BC cell is composed of separate p and n regions, and the corresponding area surface is covered with at least a dielectric film layer (such as silicon nitride).

[0098] An intermittent conductive silver paste with a solid content of 92% is set on the corresponding area of the back surface of the cell using screen printing technology and dried, and then an intermittent conductive silver paste with a solid content of 68% is set on the back surface of the cell using screen printing technology, and the conductive silver paste with a solid content of 92% and the conductive silver paste with a solid content of 68% are alternately set. After rapid sintering in a high-temperature sintering furnace, the preparation of the first conductive connecting piece and the second conductive connecting piece on the back surface of the BC cell is completed.

[0099] A conductive aluminum film is provided, the width of the aluminum film is close to the width of the first conductive connecting piece and the second conductive connecting piece, the aluminum film is covered on the first conductive connecting piece and the second conductive connecting piece, and the aluminum film is fixed on the first conductive connecting piece and the second conductive connecting piece by laser welding.

[0100] Comparative Example:

[0101] The preparation process of this comparative example is the same as steps A to J provided in Example One. The difference is that in step K, a conductive silver paste with a solid content of 97% in a continuous shape is directly set on the back surface of the cell using screen printing technology, and the preparation of the paste electrode on the back surface of the Topcon cell is completed after rapid sintering in a high-temperature sintering furnace. There is no step L and step M.

[0102] The silicon-based solar cells prepared in the above Example One and Comparative Example are characterized by electrical properties such as I-V characteristic curves using detection equipment. The results are shown in Table 1 below.

[0103] It is worth mentioning that the short-circuit current (Isc), open-circuit voltage (Voc), fill factor (FF), conversion efficiency (Eta) and series resistance (Rs) in the characterization results are calculated based on the detection results of the comparative examples. That is, the short-circuit current (Isc), open-circuit voltage (Voc), fill factor (FF), conversion efficiency (Eta) and series resistance (Rs) of the comparative examples are all taken as the basis, and the Isc, Voc, FF, Eta and Rs of the Topcon cell of Example 1 are calculated. From the results shown in Table 1, it can be seen that the silicon-based solar cell provided by the embodiment of the present application can effectively reduce the cost without significantly affecting the Isc, Voc, FF, Eta and Rs of the solar cell. That is, the technical solution provided by the embodiment of the present application can reduce the cost while basically not affecting the performance of the prepared silicon-based solar cell.

[0104]

[0105] The above steps provide an introduction for helping to understand the method, structure and core idea of the present application. For ordinary skilled persons in the technical field, the present application can be improved and modified without departing from the principles of the present application, and these improvements and modifications also belong to the protection scope of the present application.

Claims

1. A silicon-based solar cell, characterized in that: include: A silicon substrate (10), a functional layer (20) stacked on the silicon substrate (10), a first electrical connector (31), a second electrical connector (32), and a conductive film layer (33), wherein: The first electrical connectors (31) and the second electrical connectors (32) are alternately arranged in a first direction on the main surface of the functional layer (20); The conductive film layer (33) is electrically connected to the first electrical connector (31) and the second electrical connector (32); The volume of the first electrical connector (31) is different from the volume of the second electrical connector (32).

2. The silicon-based solar cell according to claim 1, characterized in that: The first electrical connectors (31) and the second electrical connectors (32) alternately arranged in the first direction form an electrical connection area; A plurality of spaced electrical connection areas (34) are provided in a second direction on the main surface of the functional layer (20), wherein the second direction is perpendicular to the first direction.

3. The silicon-based solar cell according to claim 2, characterized in that: The first electrical connectors (31) and the second electrical connectors (32) of the plurality of electrical connection areas (34) are electrically connected to the same conductive film layer (33); or, Each of the electrical connection areas (34) is connected to one of the conductive film layers (33), and any two of the electrical connection areas are connected to different conductive film layers (33).

4. The silicon-based solar cell according to any one of claims 1 to 3, characterized in that: The length of the conductive film layer (33) in the first direction is greater than the length of the silicon-based solar cell in the first direction.

5. The silicon-based solar cell according to any one of claims 1 to 3, characterized in that: Adjacent first electrical connectors (31) and second electrical connectors (32) are overlapped, connected, or spaced apart.

6. The silicon-based solar cell according to any one of claims 1 to 3, characterized in that: The conductive film layer (33) is an aluminum film layer, a copper film layer, or an aluminum-copper alloy film layer.

7. The silicon-based solar cell according to claim 1, characterized in that: The silicon-based solar cell is a TOPCon cell, and the functional layer (20) is a stacked structure consisting of a tunneling oxide layer (21), a doped polysilicon layer (22), and a passivation anti-reflection layer (23) stacked in sequence on the backlight surface of the silicon substrate (10).

8. The silicon-based solar cell according to claim 1, characterized in that: The silicon-based solar cell is a BC cell, and the backlight surface of the silicon substrate (10) is provided with spaced and alternately distributed n-type regions and p-type regions, the functional layer (20) located in the n-type region is a stacked structure consisting of a first tunneling oxide layer, an n-type doped silicon layer and a first passivation layer stacked in sequence on the backlight surface of the silicon substrate (10), and the functional layer (20) located in the p-type region is a stacked structure consisting of a second tunneling oxide layer, a p-type doped silicon layer and a second passivation layer stacked in sequence on the backlight surface of the silicon substrate (10).

9. A photovoltaic module, characterized in that: include: A battery string is formed by connecting multiple battery cells in series, where: The cell is obtained by cutting the silicon-based solar cell according to any one of claims 1 to 8, or the cell is the silicon-based solar cell according to any one of claims 1 to 8.

10. The photovoltaic module according to claim 9, characterized in that: Every two adjacent battery cells are electrically connected via the connection between the conductive film layers (33) included in the battery cells.

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