A solar cell and a method for metallizing the same, a cell module, and a photovoltaic system

Abstract

This invention relates to the field of solar cell technology, specifically disclosing a solar cell and its metallization method, a cell module, and a photovoltaic system. The cell includes: a cell body; fine grid lines disposed on the cell body, with a plurality of fine grid lines arranged along a first direction and extending along a second direction; a main grid, including a main grid base metal layer and a main grid noble metal base layer; the main grid base metal layer is disposed on the side of the fine grid lines facing away from the cell body, extending along the first direction, with a plurality of main grid base metal layers arranged along the second direction, and the main grid base metal layer includes a plurality of overlapping portions, which are stacked with the fine grid lines of the same polarity and electrically connected; the main grid noble metal base layer is at least partially disposed at the overlapping portion and the layer of the fine grid lines, and in the thickness direction of the cell body, the main grid noble metal base layer is disposed between the overlapping portion and the cell body. This invention can significantly reduce production costs while effectively improving the problems of cell conversion efficiency degradation and reduced lifespan caused by base metals, enabling the manufactured cell module to have low production costs, high conversion efficiency, and long service life.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a solar cell wafer and its metallization method, a battery module and a photovoltaic system. Background Technology

[0002] In existing technologies, the grid lines on solar cells are typically sintered using precious metals such as silver paste. However, the high price of precious metals leads to high metallization costs, hindering the widespread application of photovoltaic products. In some products, base metals such as copper and aluminum, which are cheaper than precious metals, are used to reduce metallization costs. However, due to the unique properties of base metal pastes, they easily diffuse into the silicon wafer during high-temperature sintering, forming severe recombination and affecting the cell's conversion efficiency and lifespan. Summary of the Invention

[0003] The purpose of this invention is to provide a solar cell, a metallization method thereof, a battery module, and a photovoltaic system, in light of the existing technology.

[0004] This invention can significantly reduce production costs while effectively improving the problems of battery conversion efficiency degradation and reduced lifespan caused by base metals, so that the battery components produced have low production costs, high conversion efficiency and long service life.

[0005] First, the present invention provides a solar cell, comprising: Battery body; Fine grid lines are disposed on the battery body, and a plurality of fine grid lines are arranged along a first direction and the fine grid lines extend along a second direction, with the first direction and the second direction intersecting each other. The main gate includes a base metal layer and a noble metal base layer. The main grid base metal layer is disposed on the side of the fine grid line facing away from the battery body. The main grid base metal layer extends along the first direction. A plurality of main grid base metal layers are arranged along the second direction. The main grid base metal layer includes a plurality of overlapping portions. The overlapping portions are stacked with the fine grid lines of the same polarity and are electrically connected. The main grid precious metal base layer is at least partially disposed at the overlap between the overlapping portion and the fine grid lines, and in the thickness direction of the battery body, the main grid precious metal base layer is disposed between the overlapping portion and the battery body.

[0006] In some embodiments, in the thickness direction of the battery body, the main grid noble metal base layer is disposed between the overlapping portion and the fine grid lines; or... In the thickness direction of the battery body, the main grid noble metal base layer is disposed between the fine grid lines and the battery body.

[0007] In some embodiments, the main gate noble metal base layer is continuously or intermittently arranged along the first direction.

[0008] In some embodiments, the main grid noble metal base layer includes a plurality of blocking segments spaced apart along the first direction, the blocking segments being at least partially disposed at the overlap between the overlapping portion and the fine grid lines.

[0009] In some embodiments, the width W1 of the blocking segment in the first direction is greater than or equal to the width W2 of the fine grid line in the first direction.

[0010] In some embodiments, the ratio between the width W2 of the fine grid line in the first direction and the width W1 of the blocking segment in the first direction is 1:1 to 35.

[0011] In some embodiments, the length L1 of the blocking segment in the second direction is greater than or equal to the width L2 of the overlapping portion in the second direction.

[0012] In some embodiments, the ratio between the width L2 of the overlapping portion in the second direction and the length L1 of the blocking segment in the second direction is 1:1 to 6.

[0013] In some embodiments, the fine gate lines include a first fine gate and a second fine gate arranged alternately along the first direction and having opposite polarities. The blocking segment includes a first blocking segment and a second blocking segment arranged alternately along the first direction. The first blocking segment is electrically connected to the first fine gate, and the second blocking segment is electrically connected to the second fine gate. The width W of the first blocking segment in the first direction is... 11 Smaller than the spacing W between adjacent second fine gates 31 The width W of the second blocking segment in the first direction 12 Smaller than the spacing W between adjacent first fine gates 32 .

[0014] In some embodiments, in the thickness direction of the battery body, the orthographic projection outline of the blocking segment on the battery body is any one of the following: rectangular, circular, elliptical, waist-shaped, trapezoidal, parallelogram, or polygon with more than 4 sides.

[0015] In some embodiments, the main gate noble metal base layer includes noble metal contact gate lines, which are continuously extended along the first direction.

[0016] In some embodiments, the width L3 of the noble metal contact gate line in the second direction is smaller than the width L4 of the base metal layer of the main gate in the second direction.

[0017] In some embodiments, the ratio between the width L3 of the noble metal contact gate line in the second direction and the width L4 of the base metal layer of the main gate in the second direction is 1:1 to 30.

[0018] In some embodiments, the base metal layer of the main gate and the noble metal base layer of the main gate are non-burn-through material layers, and the fine gate lines are burn-through material layers.

[0019] In some embodiments, the base metal layer of the main gate is any one of a non-burn-through silver-clad copper material layer, a non-burn-through copper material layer, or a non-burn-through aluminum material layer, the noble metal base layer of the main gate is a non-burn-through silver material layer, and the fine gate lines are burn-through silver layers.

[0020] In some embodiments, pad points are also included, the pad points being made of the same material as the noble metal base layer of the main gate.

[0021] Second, the present invention provides a method for metallizing solar cells, comprising: Noble metal grid paste and fine grid paste are printed on the battery body and sintered to form a grid noble metal base layer and fine grid lines on the battery body. The grid noble metal base layer is at least partially stacked with the fine grid lines of the same polarity. A base metal grid paste is printed on the sintered battery body and cured at low temperature to form a base metal grid layer on the battery body. The base metal grid layer includes several overlapping portions, which are located at the overlap between the base metal grid layer and the fine grid lines. In the thickness direction of the battery body, the base metal grid layer is located between the overlapping portions and the battery body.

[0022] In some embodiments, the step of printing precious metal main grid paste and fine grid paste on the battery body includes: First, print the precious metal main grid paste, then print the fine grid paste; or, First, print the fine grid paste, then print the precious metal main grid paste.

[0023] In some embodiments, the precious metal main grid paste is a non-burn-through silver paste, and the fine grid paste is a burn-through silver paste.

[0024] In some embodiments, the sintering temperature is 650℃~900℃ and the processing time is 30s~100s.

[0025] In some embodiments, the curing temperature of the low-temperature curing is lower than the sintering temperature.

[0026] In some embodiments, the base metal gate paste is any one of non-burn-through copper paste, non-burn-through silver-coated copper paste, and non-burn-through aluminum paste.

[0027] In some embodiments, the base metal gate paste is a non-burn-through copper paste or a non-burn-through silver-coated copper paste, and the low-temperature curing temperature is 150℃~400℃, with a processing time of 60s~600s; or, The base metal grid paste is a non-burn-through aluminum paste, and the low-temperature curing temperature is 450℃~750℃, with a processing time of 40s~150s.

[0028] Third, the present invention also provides a battery assembly, including the aforementioned solar cell; or, This includes solar cells prepared by one of the aforementioned solar cell metallization methods.

[0029] Fourth, the present invention provides a photovoltaic system including the above-mentioned battery module.

[0030] The beneficial effects of this invention are as follows: 1) In terms of structure, the main gate of this invention adopts a composite structure combining a base metal layer and a noble metal base layer. The noble metal base layer is at least partially located at the overlap (the part where the base metal layer and the fine gate lines are stacked) and the overlap of the fine gate lines. In the thickness direction of the battery body, the noble metal base layer is located between the overlap and the battery body. On the one hand, the main body of the main gate uses a base metal layer with low material cost, which can significantly reduce the amount of precious metals such as silver paste and effectively reduce production costs. On the other hand, the noble metal base layer between the overlap of the base metal layer and the battery body forms an effective isolation barrier at the key electrical contact interface, preventing the base metal from diffusing into the silicon wafer during subsequent processes and battery use, effectively reducing recombination. At the same time, the noble metal base layer ensures excellent ohmic contact between the fine gate lines and the battery body, as well as at the overlap between the main gate and the fine gate lines, ensuring efficient current collection and avoiding current loss due to poor contact or base metal diffusion.

[0031] Therefore, through the above-mentioned metallization structure design, the present invention can significantly reduce production costs while effectively improving the problems of battery conversion efficiency degradation and lifespan reduction caused by base metals, so that the battery components produced have low production costs, high conversion efficiency and long service life.

[0032] 2) In terms of process, this invention first prints noble metal main grid paste and fine grid paste, and then sinters them. Subsequently, base metal main grid paste is printed on the sintered battery body and cured at a low temperature, preventing the base metal main grid paste from diffusing into the substrate during the sintering process. Thus, by printing in batches and curing twice, the noble metal main grid base layer and the fine grid lines can form a stable and excellent ohmic contact and high-quality connection through high-temperature sintering, ensuring efficient current collection. At the same time, the low-temperature curing adapts to the characteristics of base metal materials, preventing base metal from diffusing into the substrate due to high temperatures, effectively reducing recombination.

[0033] Therefore, through the above-mentioned batch printing and secondary curing process design, the present invention can significantly reduce production costs while effectively improving the problems of battery conversion efficiency degradation and lifespan reduction caused by base metals, so that the battery components produced have low production costs, high conversion efficiency and long service life. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of a solar cell according to an embodiment of the present invention.

[0035] Figure 2 for Figure 1 A magnified view of part C.

[0036] Figure 3 for Figure 2 KK-direction cross-section.

[0037] Figure 4 A cross-sectional view of the intersection of the main gate and the fine gate.

[0038] Figure 5 This is a schematic diagram of the structure of a solar cell according to an embodiment of the present invention.

[0039] Figure 6 for Figure 5 A magnified view of part D.

[0040] Figure 7 This is a flowchart of a method for metallizing solar cells according to an embodiment of the present invention.

[0041] Figure 8 This is a flowchart of a method for metallizing solar cells according to an embodiment of the present invention.

[0042] Figure 9 This is a flowchart illustrating the printing of precious metal main grid paste and fine grid paste on the battery body according to an embodiment of the present invention.

[0043] Figure 10 This is a flowchart illustrating the printing of precious metal main grid paste and fine grid paste on the battery body according to an embodiment of the present invention.

[0044] In the picture: Battery body 1, fine grid line 2, first fine grid 2A, second fine grid 2B, main grid 3, first main grid 3A, second main grid 3B, main grid base metal layer 31, overlapping part 311, main grid precious metal base layer 32, blocking segment 32A, precious metal contact grid line 32B, pad point 4. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the invention, and should not be construed as limiting the invention. Furthermore, it should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0046] In the description of this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" or "a number" means two or more, unless otherwise explicitly specified.

[0047] In the description of this invention, unless otherwise expressly specified and limited, the term "above" or "below" the second feature may include direct contact between the first and second features, or contact between the first and second features not in direct contact but through another feature between them.

[0048] This invention can significantly reduce production costs while effectively improving the problems of battery conversion efficiency degradation and reduced lifespan caused by base metals, so that the battery components produced have low production costs, high conversion efficiency and long service life.

[0049] Example 1 See Figure 1 , Figure 2 , Figure 5 and Figure 6 As shown, this embodiment discloses a solar cell, comprising: Battery body 1; Fine grid lines 2 are disposed on the battery body 1. A plurality of fine grid lines 2 are arranged along a first direction and extend along a second direction. The first direction and the second direction are intersecting each other. The main gate 3 includes a main gate base metal layer 31 and a main gate noble metal base layer 32; The main grid base metal layer 31 is disposed on the side of the fine grid line 2 facing away from the battery body 1. The main grid base metal layer 31 extends along the first direction, and a plurality of main grid base metal layers 31 are arranged along the second direction. The main grid base metal layer 31 includes a plurality of overlapping portions 311. The overlapping portions 311 are stacked with the fine grid line 2 of the same polarity and are electrically connected. The main grid precious metal base layer 32 is at least partially disposed at the overlap of the overlap portion 311 and the fine grid line 2, and in the thickness direction of the battery body 1, the main grid precious metal base layer 32 is disposed between the overlap portion 311 and the battery body 1.

[0050] In this invention, the main grid 3 adopts a composite structure combining a base metal layer 31 and a noble metal base layer 32. The noble metal base layer 32 is at least partially disposed at the overlap between the overlap portion 311 (the portion where the base metal layer 31 and the fine grid lines 2 overlap) and the fine grid lines 2. Furthermore, in the thickness direction of the battery body 1, the noble metal base layer 32 is disposed between the overlap portion 311 and the battery body 1. On the one hand, the main body of the main grid 3 uses the inexpensive base metal layer 31, which can significantly reduce the amount of precious metals such as silver paste used, effectively reducing production costs. On the one hand, production costs are reduced; on the other hand, by forming an effective isolation barrier at the critical electrical contact interface through the main gate noble metal base layer 32 between the overlap portion 311 of the main gate base metal layer 31 and the battery body 1, the base metal is prevented from diffusing into the silicon wafer during subsequent processes and battery use, effectively reducing recombination; at the same time, the main gate noble metal base layer 32 can ensure that excellent ohmic contact is formed between the fine gate line 2 and the battery body 1, and at the overlap between the main gate 3 and the fine gate line 2, ensuring efficient current collection and avoiding current loss caused by poor contact or base metal diffusion.

[0051] Therefore, through the above-mentioned metallization structure design, the present invention can significantly reduce production costs while effectively improving the problems of battery conversion efficiency degradation and lifespan reduction caused by base metals, so that the battery components produced have low production costs, high conversion efficiency and long service life.

[0052] Experiments have shown that, taking a back-contact battery as an example, compared to existing battery structures where both the main grid and the fine grid use silver paste, the metallization material cost of the battery module of this invention can be reduced. 10%~50% .

[0053] It is understood that the battery body 1 may include a substrate and a doped layer, passivation layer, antireflection layer, etc. disposed on at least one end face of the substrate, but is not limited thereto.

[0054] In practical applications, the embodiments of the present invention do not specifically limit the material and conductivity type of the substrate. For example, the substrate can be a silicon substrate, such as monocrystalline silicon, microcrystalline silicon, polycrystalline silicon, or amorphous silicon, or a germanium-silicon substrate, a germanium substrate, or a gallium arsenide substrate, but is not limited thereto. Its conductivity type can be N-type or P-type. Preferably, the substrate is a silicon substrate.

[0055] The doped layer includes a first doped layer and a second doped layer with opposite polarities. In terms of conductivity type, the polarity of the first doped layer or the second doped layer can be the same as or opposite to the polarity of the substrate, as long as the polarity of the first doped layer is opposite to that of the second doped layer. The material of either the first doped layer or the second doped layer is monocrystalline silicon, microcrystalline silicon, polycrystalline silicon, or amorphous silicon doped with p-type dopants (such as group III elements such as B, Ga, or In), and the material of the other is monocrystalline silicon, microcrystalline silicon, polycrystalline silicon, or amorphous silicon doped with n-type dopants (such as group V elements such as P, As, or Sb).

[0056] In some embodiments, see Figure 1 and Figure 3 As shown, in the thickness direction of the battery body 1, the main grid noble metal base layer 32 is disposed between the overlapping portion 311 and the fine grid line 2; or, See Figure 1 and Figure 4 As shown, in the thickness direction of the battery body 1, the main grid noble metal base layer 32 is disposed between the fine grid line 2 and the battery body 1.

[0057] Specifically, in the first embodiment, the main grid noble metal base layer 32 is disposed between the overlapping portion 311 and the fine grid line 2 in the thickness direction of the battery body 1; in the second embodiment, the main grid noble metal base layer 32 is disposed between the fine grid line 2 and the battery body 1 in the thickness direction of the battery body 1.

[0058] In some embodiments, the base metal layer 31 of the main gate and the noble metal base layer 32 of the main gate are non-burn-through material layers, and the fine gate line 2 is a burn-through material layer.

[0059] Understandably, the non-burn-through material layer is sintered from a non-burn-through slurry. During the sintering process, the non-burn-through slurry does not react with the passivation layer and does not burn through it. The burn-through material layer is sintered from a burn-through slurry. During the sintering process, the burn-through slurry can react with the passivation layer and burn through it.

[0060] On the one hand, the main grid 3 as a whole (including the main grid base metal layer 31 and the main grid noble metal base layer 32 below it) adopts a non-burn-through material layer, which avoids additional damage to the passivation layer on the surface of the battery body 1 during the sintering process, reduces substrate surface recombination, and helps to improve the open-circuit voltage and overall conversion efficiency of the battery. On the other hand, the fine grid adopts a burn-through material layer, whose slurry can accurately burn through the passivation layer on the surface of the battery body 1 during the sintering process, forming a direct and excellent ohmic contact with the underlying substrate, ensuring that photogenerated carriers can be efficiently collected and reducing series resistance losses. As a result, the conversion efficiency of the battery module can be further improved while significantly reducing production costs.

[0061] In some embodiments, the base metal layer 31 of the main gate is any one of a non-burn-through silver-clad copper material layer, a non-burn-through copper material layer, or a non-burn-through aluminum material layer, the noble metal base layer 32 of the main gate is a non-burn-through silver material layer, and the fine gate line 2 is a burn-through silver layer.

[0062] In some embodiments, see Figure 1 and Figure 5 As shown, it also includes pad point 4, which is made of the same material as the main grid precious metal base layer 32.

[0063] In some embodiments, when the battery cell is a back-contact battery, the fine grid lines 2 include a first fine grid 2A and a second fine grid 2B arranged alternately along a first direction and having opposite polarities, and the main grid 3 includes a first main grid 3A and a second main grid 3B arranged alternately along a second direction and having opposite polarities.

[0064] Understandably, the fine grid line 2 can have blank areas where the fine grid paste is not printed at the locations of the main grid 3, pad point 4, and other oppositely polarized conductive components (such as...). Figure 1 As shown in the figure, insulating adhesive (not shown in the figure) can also be printed near this location to electrically isolate it from opposite polarity conductive parts. The above-mentioned electrical isolation structure can be found in the prior art and will not be described in detail here.

[0065] In some embodiments, the main grid noble metal base layer 32 is provided intermittently or continuously along the first direction.

[0066] When an intermittent setting is adopted, the blocking and anti-diffusion effect of local contact can be enhanced; when a continuous extension setting is adopted, the continuity of overall current collection and transmission can be enhanced. Thus, different types of main grid precious metal base layers 32 can be selected based on different actual performance requirements and cost control objectives.

[0067] Example 2 In some embodiments, see Figure 1 As shown, the main grid noble metal base layer 32 is intermittently arranged along the first direction.

[0068] In some embodiments, see Figures 1 to 4 As shown, the main grid precious metal base layer 32 includes a plurality of blocking segments 32A arranged at intervals along the first direction, and the blocking segments 32A are at least partially disposed at the overlap of the overlap portion 311 and the fine grid line 2.

[0069] Understandably, the blocking segment 32A is at least partially disposed at the overlap between the overlapping portion 311 and the fine grid line 2. This can be either the blocking segment 32A being disposed between the overlapping portion 311 and the fine grid line 2 in the thickness direction of the battery body 1, or the blocking segment 32A being disposed between the fine grid line 2 and the battery body 1 in the thickness direction of the battery body 1, with the overlapping portion 311 being disposed on the side of the fine grid line 2 facing away from the battery body 1.

[0070] By setting the blocking segments 32A at intervals, and with the blocking segments 32A at least partially located at the overlap of the overlap portion 311 and the fine grid line 2, an effective isolation barrier can be formed in the critical overlap area, effectively reducing recombination and ensuring efficient current collection. Furthermore, the segmented design of the main grid precious metal base layer 32 can further reduce the overall amount of precious metal used, thereby further reducing production costs.

[0071] In some embodiments, see Figure 2 As shown, the width W1 of the blocking segment 32A in the first direction is greater than or equal to the width W2 of the fine grid line 2 in the first direction.

[0072] That is, W1≥W2. In this case, the blocking segment 32A can fully cover the overlapping area of ​​the overlapping portion 311 and the fine grid line 2, resulting in a better blocking effect and ensuring the stability of the ohmic contact between the fine grid line 2 and the main grid 3, and between the fine grid line 2 and the battery body 1. Preferably, W1>W2. In this case, the blocking segment 32A can more fully cover the overlapping area of ​​the overlapping portion 311 and the fine grid line 2. During the printing process, the blocking segment 32A is allowed to have a certain positional offset relative to the fine grid line 2 in the first direction, reducing the accuracy requirements and reducing the production difficulty. At the same time, since the blocking segment 32A is intermittently set, W1>W2 does not require an additional amount of precious metals. Thus, the optimal balance between electrical performance and cost control can be achieved.

[0073] In some embodiments, see Figure 2 As shown, the ratio between the width W2 of the fine grid line 2 in the first direction and the width W1 of the blocking segment 32A in the first direction is 1:1~35.

[0074] W2 / W1 can be 1:1, 1:5, 1:10, 1:12, 1:15, 1:20, 1:25, 1:26, 1:27, 1:28, 1:29, 1:30, 1:31, 1:32, 1:33, 1:34, or 1:35, but is not limited to these.

[0075] Within this range, it can be ensured that the blocking segment 32A can fully cover the overlapping area of ​​the overlap portion 311 and the fine grid line 2, while avoiding the increase of unnecessary precious metal consumption.

[0076] In some embodiments, see Figure 2 As shown, the length L1 of the blocking segment 32A in the second direction is greater than or equal to the width L2 of the overlapping portion 311 in the second direction.

[0077] Because the blocking segments 32A are arranged intermittently, by setting L1>L2, it is possible to ensure that the blocking segments 32A fully cover the overlapping area of ​​the overlapping part 311 and the fine grid line 2 while ensuring that the consumption of precious metals is relatively small. This allows for a certain degree of process deviation between the base metal layer 31 of the main grid and the blocking segments 32A in the second direction during printing, so that the manufactured battery module has both low production cost, high conversion efficiency and long service life.

[0078] In some embodiments, see Figure 2 As shown, the ratio between the width L2 of the overlapping portion 311 in the second direction and the length L1 of the blocking segment 32A in the second direction is 1:1 to 6.

[0079] For example, L2 / L1 can be 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5 or 1:6, but is not limited thereto.

[0080] Within this range, it can be ensured that unnecessary precious metal consumption will not be increased due to the length L1 of the blocking segment 32A in the second direction being too large relative to the width L2 of the overlapping portion 311 in the second direction.

[0081] In some embodiments, see Figure 1 As shown, when the battery cell is a back-contact battery, the fine grid lines 2 include a first fine grid 2A and a second fine grid 2B arranged alternately along a first direction and with opposite polarities. The blocking segment 32A includes a first blocking segment and a second blocking segment arranged alternately along a first direction. The first blocking segment is electrically connected to the first fine grid 2A, and the second blocking segment is electrically connected to the second fine grid 2B. The width W of the first blocking segment in the first direction is... 11 Smaller than the spacing W between adjacent second fine grids 2B 31 The width W of the second blocking segment in the first direction 12Smaller than the spacing W between adjacent first fine grids 2A 32 .

[0082] Through W 11 <W 31 and W 12 <W 32 The setting avoids short circuits caused by contact between adjacent opposite segments 32A and fine grid lines 2.

[0083] Understandably, when the battery cell is a back-contact battery, the main grid 3 includes a first main grid 3A and a second main grid 3B that are alternately arranged along the second direction and have opposite polarities.

[0084] In some embodiments, in the thickness direction of the battery body 1, the orthographic projection outline of the blocking segment 32A on the battery body 1 is any one of the following: rectangular, circular, elliptical, oblong, trapezoidal, parallelogram, or polygon with more than 4 sides. For example... Figure 1 The orthographic projection outline shown is a rectangle.

[0085] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the structure and implementation principle of the solar cell described above can be referred to the corresponding structure and implementation principle in the aforementioned Embodiment 1, and will not be repeated here.

[0086] Example 3 In some embodiments, see Figure 5 As shown, the main grid noble metal base layer 32 extends continuously along the first direction.

[0087] In some embodiments, see Figure 5 and Figure 6 As shown, the main gate noble metal base layer 32 includes noble metal contact gate lines 32B, which are continuously extended along the first direction.

[0088] The continuously extending noble metal contact grid line 32B can form an uninterrupted and stable electrical connection with the intersecting fine grid line 2, reducing contact resistance and thus ensuring that the current is collected from the fine grid line 2 more efficiently and stably by the main grid 3.

[0089] In some embodiments, the width L3 of the noble metal contact gate line 32B in the second direction is equal to the width L4 of the base metal layer 31 of the main gate in the second direction.

[0090] In some embodiments, preferably, see Figure 6 As shown, the width L3 of the noble metal contact gate line 32B in the second direction is smaller than the width L4 of the base metal layer 31 of the main gate in the second direction.

[0091] By using an L3 < L4 design, the battery's conductivity, long-term reliability, and production cost can be effectively balanced, ensuring that less precious metal material is used to provide better ohmic contact and diffusion barrier effects.

[0092] In some embodiments, see Figure 6 As shown, the ratio between the width L3 of the noble metal contact gate line 32B in the second direction and the width L4 of the base metal layer 31 of the main gate in the second direction is 1:1 to 30.

[0093] For example, L3 / L4 can be 1:1, 1:5, 1:10, 1:12, 1:15, 1:20, 1:25, 1:26, 1:27, 1:28, 1:29 or 1:30, but is not limited thereto.

[0094] Within this range, a good balance can be struck between battery conductivity, long-term reliability, and production cost. When L3 is too small relative to L4, conductivity and long-term reliability are poor. When L3 is too large relative to L4, the amount of precious metals used increases significantly, which greatly increases production costs. However, the resulting improvement in conductivity and long-term reliability is limited and cannot match the increased cost, thus reducing the cost-effectiveness.

[0095] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the structure and implementation principle of the solar cell described above can be referred to the corresponding structure and implementation principle in the aforementioned Embodiment 1, and will not be repeated here.

[0096] Example 4 In some embodiments, the main gate noble metal base layer 32 extends continuously along the first direction.

[0097] In this embodiment, the main gate noble metal base layer 32 includes both noble metal contact gate line 32B and blocking segment 32A.

[0098] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the structure and implementation principle of the solar cell described above can be referred to the corresponding structure and implementation principle in the aforementioned Embodiments 1 to 3, and will not be repeated here.

[0099] Example 5 See Figure 7 As shown, this embodiment discloses a method for metallizing solar cells, including: S100. Print precious metal main grid 3 paste and fine grid paste on the battery body 1 and sinter them to form main grid precious metal base layer 32 and fine grid line 2 on the battery body 1. The main grid precious metal base layer 32 is at least partially stacked with the fine grid line 2 of the same polarity. S200. Print base metal grid paste on the sintered battery body 1 and cure it at low temperature to form a base metal grid layer 31 on the battery body 1. The base metal grid layer 31 includes several overlapping portions 311. The overlapping portions 311 are disposed at the overlap of the base metal grid layer 32 and the fine grid line 2. In the thickness direction of the battery body 1, the base metal grid layer 32 is disposed between the overlapping portions 311 and the battery body 1.

[0100] For details, see Figure 1 , Figure 2 .、 Figure 5 , Figure 6 and Figure 8 As shown, the steps in step S100 above include: S110. Print precious metal main grid paste and fine grid paste on the battery body 1; S120. Sintering is carried out.

[0101] For details, see Figure 8 As shown, the steps in step S200 above include: S210. Print base metal grid paste on the sintered battery body 1; S220. Perform low-temperature curing.

[0102] In terms of process, this invention first prints noble metal main grid paste 3 and fine grid paste, and then sinters them. Subsequently, base metal main grid paste is printed on the sintered battery body 1 and cured at low temperature to prevent the base metal main grid paste from diffusing into the substrate during the sintering process. Thus, by printing in batches and curing twice, the noble metal main grid 3 substrate and the fine grid lines 2 can form a stable and excellent ohmic contact and high-quality connection through high-temperature sintering, ensuring efficient current collection. At the same time, the low-temperature curing adapts to the characteristics of base metal materials, preventing base metal from diffusing into the substrate due to high temperatures, effectively reducing recombination.

[0103] In terms of structure, in this invention, the main grid 3 adopts a composite structure combining a main grid base metal layer 31 and a main grid noble metal base layer 32. The main grid noble metal base layer 32 is at least partially disposed at the overlap portion 311 (the portion where the main grid base metal layer 31 and the fine grid lines 2 overlap) and the overlap portion of the fine grid lines 2. Furthermore, in the thickness direction of the battery body 1, the main grid noble metal base layer 32 is disposed between the overlap portion 311 and the battery body 1. On the one hand, the main body of the main grid 3 uses the inexpensive main grid base metal layer 31, which can significantly reduce the amount of precious metals such as silver paste used, effectively... On the one hand, production costs are reduced; on the other hand, by forming an effective isolation barrier at the critical electrical contact interface through the main gate noble metal base layer 32 between the overlap portion 311 of the main gate base metal layer 31 and the battery body 1, the base metal is prevented from diffusing into the silicon wafer during subsequent processes and battery use, effectively reducing recombination; at the same time, the main gate noble metal base layer 32 can ensure that excellent ohmic contact is formed between the fine gate line 2 and the battery body 1, and at the overlap between the main gate 3 and the fine gate line 2, ensuring efficient current collection and avoiding current loss caused by poor contact or base metal diffusion.

[0104] Therefore, by combining the above-mentioned batch printing and secondary curing process design with the metallization structure design, the present invention can significantly reduce production costs while effectively improving the problems of battery conversion efficiency degradation and lifespan reduction caused by base metals, so that the battery components produced have low production costs, high conversion efficiency and long service life.

[0105] In some embodiments, see Figures 9 to 10 As shown, the step of printing precious metal main grid 3 paste and fine grid paste on the battery body 1 (step S110) includes: First, print the precious metal main grid paste, then print the fine grid paste; or, First, print the fine grid paste, then print the precious metal main grid 3 paste.

[0106] That is, the printing order of the fine grid paste and the precious metal main grid 3 paste can be interchanged and is not restricted by a specific order. When the fine grid paste is printed before the precious metal main grid 3 paste, the sintered precious metal main grid 3 layer is located on the side of the fine grid line 2 facing away from the battery body 1. When the precious metal main grid 3 paste is printed before the fine grid paste, the sintered precious metal main grid 3 layer is located on the side of the fine grid line 2 facing the battery body 1.

[0107] Specifically, in the first specific implementation method, see [link to relevant documentation]. Figure 9 As shown, the step of printing precious metal main grid 3 paste and fine grid paste on the battery body 1 (step S110) includes: S111a. Printing precious metal main grid paste 3; S112a. Print fine grid paste on the battery body 1, which has been printed with precious metal grid paste 3.

[0108] In the second specific implementation, see Figure 10 As shown, the step of printing precious metal main grid 3 paste and fine grid paste on the battery body 1 (step S110) includes: S111b. Printing fine grid paste; S112b. Printing precious metal grid 3 paste on the battery body 1 which has been printed with fine grid paste.

[0109] In some embodiments, the precious metal main grid 3 paste is a non-burn-through silver paste, and the fine grid paste is a burn-through silver paste.

[0110] During the sintering process, the non-burn-through silver paste does not react with the passivation layer and does not burn through the passivation layer; during the sintering process, the burn-through silver paste can react with the passivation layer and burn through the passivation layer, forming excellent ohmic contact with the substrate.

[0111] In some embodiments, the sintering temperature is 650℃~900℃ and the processing time is 30s~100s.

[0112] For example, the sintering temperature may be 650°C, 680°C, 700°C, 720°C, 750°C, 780°C, 800°C, 820°C, 850°C, 880°C or 900°C, but is not limited thereto; the processing time may be 30s, 40s, 50s, 60s, 70s, 80s, 90s or 100s, but is not limited thereto.

[0113] In some embodiments, preferably, the curing temperature of low-temperature curing is lower than that of sintering, which can further prevent base metals from diffusing into the substrate due to high temperature and effectively reduce the composite.

[0114] In some embodiments, the base metal gate paste is any one of non-burn-through copper paste, non-burn-through silver-coated copper paste, and non-burn-through aluminum paste.

[0115] In some embodiments, the base metal gate paste is a non-burn-through copper paste or a non-burn-through silver-coated copper paste, and the curing temperature for low-temperature curing is 150°C to 400°C, and the processing time is 60s to 600s.

[0116] For example, when the base metal gate paste is a non-burn-through copper paste or a non-burn-through silver-coated copper paste, the curing temperature for low-temperature curing is 150℃, 180℃, 200℃, 220℃, 250℃, 280℃, 300℃, 320℃, 350℃, 380℃ or 400℃, but is not limited thereto; the processing time can be 60s, 100s, 120s, 150s, 200s, 250s, 300s, 350s, 400s, 450s, 480s, 500s, 550s or 600s, but is not limited thereto.

[0117] Within this curing temperature range, it is possible to ensure that the base metal paste is fully cured and forms a dense, low-resistance conductive layer, while avoiding excessive curing temperature that could cause the base metal gate paste to diffuse into the substrate and increase the composite.

[0118] In some embodiments, the base metal grid paste is a non-burn-through aluminum paste, and the curing temperature for low-temperature curing is 450°C to 750°C, with a processing time of 40s to 150s.

[0119] For example, when the base metal grid paste is a non-burn-through aluminum paste, the curing temperature for low-temperature curing can be 450℃, 500℃, 550℃, 600℃, 650℃, 700℃, 720℃ or 750℃, but is not limited to these; the processing time can be 40s, 50s, 60s, 70s, 80s, 90s, 100s, 110s, 120s, 130s, 140s or 150s, but is not limited to these.

[0120] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the structure and implementation principle of the solar cell described above can be referred to the corresponding structure and implementation principle in the aforementioned Embodiments 1 to 3, and will not be repeated here.

[0121] Example 6 This embodiment discloses a battery assembly, including the aforementioned solar cell; or... This includes solar cells prepared by one of the aforementioned solar cell metallization methods.

[0122] A battery assembly may include multiple battery cells, which can be connected in series to form a battery string. The battery strings can be connected in series, in parallel, or in a series-parallel combination to achieve current output. For example, the connection between the battery cells can be achieved by welding solder strips, or the connection between the battery strings can be achieved by busbars.

[0123] The battery assembly may also include a metal frame, a backsheet, photovoltaic glass, and an encapsulant film (not shown in the figures).

[0124] This embodiment also provides a photovoltaic system, including the aforementioned battery module.

[0125] In this embodiment, the photovoltaic system can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants. It can also be applied to equipment or devices that utilize solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it is understood that the application scenarios of the photovoltaic system are not limited to these; that is, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking a photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple battery modules; for example, multiple battery modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, which can collect the current generated by the photovoltaic array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to achieve solar power supply.

[0126] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the structure and implementation principle of the solar cell described above can be referred to the corresponding structure and implementation principle in the aforementioned Embodiments 1 to 5, and will not be repeated here.

[0127] In the description of this specification, references to terms such as "some embodiments," "exemplary," "example," "implementation," or "for example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0128] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A solar cell, characterized in that, include: Battery body; Fine grid lines are disposed on the battery body, and a plurality of fine grid lines are arranged along a first direction and the fine grid lines extend along a second direction, with the first direction and the second direction intersecting each other. The main gate includes a base metal layer and a noble metal base layer. The main grid base metal layer is disposed on the side of the fine grid line facing away from the battery body. The main grid base metal layer extends along the first direction. A plurality of main grid base metal layers are arranged along the second direction. The main grid base metal layer includes a plurality of overlapping portions. The overlapping portions are stacked with the fine grid lines of the same polarity and are electrically connected. The main grid precious metal base layer is at least partially disposed at the overlap between the overlapping portion and the fine grid lines, and in the thickness direction of the battery body, the main grid precious metal base layer is disposed between the overlapping portion and the battery body.

2. A solar cell according to claim 1, characterized in that, In the thickness direction of the battery body, the main grid noble metal base layer is disposed between the overlapping portion and the fine grid lines; or, In the thickness direction of the battery body, the main grid noble metal base layer is disposed between the fine grid lines and the battery body.

3. A solar cell according to claim 1, characterized in that, In the same first direction, the main grid noble metal base layer is continuously extended or intermittently arranged along the first direction.

4. A solar cell according to claim 1, characterized in that, The main grid precious metal base layer includes a plurality of blocking segments arranged at intervals along the first direction, and the blocking segments are at least partially disposed at the overlap between the overlapping portion and the fine grid line.

5. A solar cell according to claim 4, characterized in that, The width W1 of the blocking segment in the first direction is greater than or equal to the width W2 of the fine grid line in the first direction.

6. A solar cell according to claim 4, characterized in that, The ratio between the width W2 of the fine grid line in the first direction and the width W1 of the blocking segment in the first direction is 1:1~35.

7. A solar cell according to claim 4, characterized in that, The length L1 of the blocking segment in the second direction is greater than or equal to the width L2 of the overlapping portion in the second direction.

8. A solar cell according to claim 4, characterized in that, The ratio between the width L2 of the overlapping portion in the second direction and the length L1 of the blocking segment in the second direction is 1:1~6.

9. A solar cell according to claim 4, characterized in that, The fine grid lines include a first fine grid and a second fine grid arranged alternately along the first direction and having opposite polarities. The blocking segment includes a first blocking segment and a second blocking segment arranged alternately along the first direction. The first blocking segment is electrically connected to the first fine grid, and the second blocking segment is electrically connected to the second fine grid. The width W of the first blocking segment in the first direction is... 11 Smaller than the spacing W between adjacent second fine gates 31 The width W of the second blocking segment in the first direction 12 Smaller than the spacing W between adjacent first fine gates 32 .

10. A solar cell according to claim 4, characterized in that, In the thickness direction of the battery body, the orthographic projection outline of the blocking segment on the battery body is any one of the following: rectangular, circular, elliptical, waist-shaped, trapezoidal, parallelogram, or polygon with more than 4 sides.

11. A solar cell according to any one of claims 1 to 10, characterized in that, The main grid precious metal base layer includes precious metal contact grid lines, which are continuously extended along the first direction.

12. A solar cell according to claim 11, characterized in that, The width L3 of the noble metal contact gate line in the second direction is smaller than the width L4 of the base metal layer of the main gate in the second direction.

13. A solar cell according to claim 11, characterized in that, The ratio between the width L3 of the noble metal contact gate line in the second direction and the width L4 of the base metal layer of the main gate in the second direction is 1:1~30.

14. A solar cell according to claim 1, characterized in that, The base metal layer of the main gate and the noble metal base layer of the main gate are non-burn-through material layers, while the fine gate lines are burn-through material layers.

15. A solar cell according to claim 14, characterized in that, The base metal layer of the main gate is any one of a non-burn-through silver-clad copper material layer, a non-burn-through copper material layer, or a non-burn-through aluminum material layer; the noble metal base layer of the main gate is a non-burn-through silver material layer; and the fine gate lines are burn-through silver layers.

16. A solar cell according to claim 1, characterized in that, It also includes pad points, which are made of the same material as the precious metal base layer of the main gate.

17. A method for metallizing solar cells, characterized in that, include: Noble metal grid paste and fine grid paste are printed on the battery body and sintered to form a grid noble metal base layer and fine grid lines on the battery body. The grid noble metal base layer is at least partially stacked with the fine grid lines of the same polarity. A base metal grid paste is printed on the sintered battery body and cured at low temperature to form a base metal grid layer on the battery body. The base metal grid layer includes several overlapping portions, which are located at the overlap between the base metal grid layer and the fine grid lines. In the thickness direction of the battery body, the base metal grid layer is located between the overlapping portions and the battery body.

18. A method for metallizing a solar cell according to claim 17, characterized in that, The steps of printing precious metal main grid paste and fine grid paste on the battery body include: First, print the precious metal main grid paste, then print the fine grid paste; or, First, print the fine grid paste, then print the precious metal main grid paste.

19. A method for metallizing a solar cell according to claim 17, characterized in that, The precious metal grid paste is a non-burn-through silver paste, and the fine grid paste is a burn-through silver paste.

20. A method for metallizing a solar cell according to claim 19, characterized in that, The sintering temperature is 650℃~900℃, and the processing time is 30s~100s.

21. A method for metallizing a solar cell according to claim 17, characterized in that, The curing temperature of the low-temperature curing is lower than the sintering temperature.

22. A method for metallizing a solar cell according to claim 17, characterized in that, The base metal grid paste is any one of the following: non-burn-through copper paste, non-burn-through silver-coated copper paste, and non-burn-through aluminum paste.

23. A method for metallizing a solar cell according to claim 22, characterized in that, The base metal grid paste is a non-burn-through copper paste or a non-burn-through silver-coated copper paste, and the low-temperature curing temperature is 150℃~400℃, with a processing time of 60s~600s; or, The base metal grid paste is a non-burn-through aluminum paste, and the low-temperature curing temperature is 450℃~750℃, with a processing time of 40s~150s.

24. A battery assembly, characterized in that, Including a solar cell according to any one of claims 1 to 16; or, This includes solar cells prepared by a solar cell metallization method according to any one of claims 17 to 23.

25. A photovoltaic system, characterized in that, Includes the battery assembly as described in claim 24.

Images