Sintering method of solar cell and solar cell obtained thereby

Abstract

The invention provides a solar cell sintering method and a solar cell obtained through the solar cell sintering method, and relates to the technical field of solar cells. The sintering method of the solar cell comprises the following steps of: printing P fine grid slurry on a cell piece, and sintering for the first time; printing N fine grid slurry, and sintering for the second time; and finally printing the main grid slurry, and performing third sintering to obtain the solar cell. According to the sintering method, a step-by-step sintering mode is adopted, the contact effect of metal of the P region, the N region and the main grid region and the silicon wafer is improved, and the efficiency and the process yield of the solar cell can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a sintering method for solar cells and a solar cell obtained thereby, and in particular to a sintering method for TBC cells and a solar cell obtained thereby. Background Art

[0002] TBC cells are back-contact crystalline silicon solar cells with high-quality interdigitated P and N regions on the back of the cell. TBC cells are characterized by the PN junction and metal contact being located on the back of the cell, leaving the front (i.e., the light-receiving side) free from any metal grid obstruction. This results in higher short-circuit current. The back of the cell also allows for wider metal grid lines, reducing series resistance and improving fill factor.

[0003] The main function of the electrode busbar is to collect the current generated by the photovoltaic effect of the cell and conduct it to the external circuit for storage or use. Currently, the preparation of the electrode busbar mainly relies on a burn-through slurry. Through high-temperature sintering or laser-assisted sintering, the slurry etches the passivation film structure on the surface of the cell, contacting the doped polysilicon layer below, collecting the current and converging it to the electrode busbar.

[0004] In the prior art, the electrode grid lines of TBC batteries are mainly prepared by printing conductive paste. Figure 1 The process (shown in Figure 1) includes sequentially printing busbar paste, drying, printing N-fine grid paste, drying, printing P-fine grid paste, and sintering. The existing TBC cell sintering process is characterized by significant differences in the sintering temperatures required for the busbar, N-fine grid, and P-fine grid pastes. Currently, all three pastes are printed and then sintered simultaneously. This sintering temperature makes it difficult to achieve optimal sintering for all three pastes. Furthermore, the metal-to-silicon contact in the P, N, and busbar regions is poor, increasing cell recombination and reducing the cell's photovoltaic conversion efficiency.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The object of the present invention is to provide a sintering method for a solar cell and a solar cell obtained thereby, wherein the sintering method improves the metal-silicon contact effect in the P region, N region and main grid region of the solar cell, thereby significantly improving the efficiency of the solar cell.

[0007] In order to achieve the above objectives, the following technical solutions are proposed:

[0008] In a first aspect, the present invention provides a sintering method for a solar cell, comprising:

[0009] First, the P fine grid paste is printed on the battery sheet, and the first sintering is performed; then the N fine grid paste is printed, and the second sintering is performed; finally, the main grid paste is printed, and the third sintering is performed, to obtain a solar cell.

[0010] Further, the first sintering, the second sintering and the third sintering adopt a gradient cooling sintering mode, and the temperature difference between each adjacent sintering is 50-250℃.

[0011] Further, the temperature range of the first sintering, the second sintering and the third sintering is 1050-350℃.

[0012] Further, the peak temperature of the first sintering is 550-1050℃; and the time of the first sintering is 1-300s.

[0013] Further, the peak temperature of the second sintering is 450-950℃; and the time of the second sintering is 1-300s.

[0014] Further, the peak temperature of the third sintering is 350-850℃; and the time of the second sintering is 1-300s.

[0015] Further, the line width of the P fine grid formed by the first sintering is 5-50μm; the line height of the P fine grid is 1-20μm; and the interval between two adjacent P fine grids is 200-4000μm.

[0016] Further, the line width of the N fine grid formed by the second sintering is 5-50μm; the line height of the N fine grid is 1-20μm; and the interval between two adjacent N fine grids is 200-4000μm.

[0017] Further, the line width of the main grid formed by the third sintering is 20-200μm; and the line height of the main grid is 1-20μm.

[0018] Further, the P fine grid paste, the N fine grid paste and the main grid paste are selected from any one or a combination of at least two of silver paste, aluminum paste, nickel paste or copper paste.

[0019] In the second aspect, the present application provides a solar cell prepared by the sintering method of the solar cell as described in the first aspect.

[0020] Further, the solar cell includes any one of a TBC cell, a TOPCon cell or a PERC cell.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] The present application improves the contact effect of the metal and the silicon wafer in the P region, the N region and the main grid region by using different sintering temperatures in different printing areas, and the efficiency of the solar cell is significantly improved after the metallization process. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the specific embodiments or the prior art, the drawings needed to be used in the specific embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0024] Figure 1 The flow chart of the traditional sintering method of the solar cell provided in the prior art.

[0025] Figure 2 The flow chart of the sintering method of the solar cell provided in the present application. DETAILED DESCRIPTION

[0026] Unless otherwise defined herein, scientific and technical terms used in connection with the present application shall have the meanings that are commonly understood by those of ordinary skill in the art. Clear indications to the contrary are necessary to overcome the plain and ordinary meaning of the term when used in the following written specification and accompanying drawings. In this application, the use of "or" means "and / or" unless specifically stated otherwise, for example, a condition is A or B means A or B or both A and B. Also, the use of "comprise", "comprises", "comprising", "containing", "contains", "contain" or any other variation thereof, are intended to refer to a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises, contains or contains elements or steps who does not include other non-recited elements or steps does not exclude the other non-recited elements or steps. Notwithstanding, nothing in this specification should be construed as indicating any non-fungible patentable subject matter.

[0027] It should be noted that specific details are set forth in the following description in order to provide a thorough understanding of the application. However, the present application can be practiced in a variety of ways beyond those described herein, which will be apparent to those skilled in the art. It is therefore intended that the present application not be limited to the specifically described embodiments and should be construed to encompass all alternatives falling within the scope of the present application.

[0028] The technical solutions of the present application will be described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort are within the scope of protection of the present application.

[0029] In a first aspect, the present application provides a sintering method of a solar cell, as shown in Figure 2 The sintering method of the solar cell comprises:

[0030] First, print P fine grid paste on the battery piece, and perform first sintering; then print N fine grid paste, and perform second sintering; finally, print main grid paste, and perform third sintering, to obtain a solar cell.

[0031] In the present application, the step-by-step sintering method is adopted, the paste parameters can be adjusted, the contact performance and passivation effect are improved, and the thermal shock of single high temperature on the substrate (such as silicon wafer) and passivation layer (such as SiN x / AlO x ) can be reduced, and warping or cracking can be avoided. And sintering P fine grid and N fine grid first can fix their geometric shape (such as aspect ratio), prevent fine grid collapse and disconnection caused by pressure or solvent erosion during subsequent main grid printing. At the same time, step-by-step sintering ensures full alloying of each layer of paste (such as the formation of Ag-Si contact), reduces contact resistance; the last sintering of the main grid can optimize the ohmic connection with the fine grid and reduce the overall resistance. In addition, it can also effectively improve the process yield, for example, after each sintering, defects can be located by electrical or optical detection, and defective products can be repaired or rejected in time to avoid problem accumulation after final sintering; if all pastes are sintered at one time, the whole cell is scrapped due to problems such as detachment and bulging; step-by-step sintering can adjust the process locally, avoiding the risk of one-time failure and reducing losses.

[0032] As an optional implementation, the first sintering, the second sintering and the third sintering adopt gradient cooling sintering, and the temperature difference between each adjacent sintering is 50-250℃, for example, it can be 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, etc.

[0033] As an optional implementation, the temperature range of the first sintering, the second sintering and the third sintering is 1050-350℃, for example, it can be 1050℃, 1000℃, 950℃, 900℃, 850℃, 800℃, 750℃, 700℃, 650℃, 600℃, 550℃, 500℃, 450℃, 400℃, 350℃, etc.

[0034] As an optional implementation, the peak temperature of the first sintering is 550-1050℃, for example, it can be 550℃, 570℃, 590℃, 610℃, 630℃, 650℃, 670℃, 690℃, 710℃, 730℃, 750℃, 770℃, 790℃, 810℃, 830℃, 850℃, 870℃, 890℃, 910℃, 930℃, 950℃, 970℃, 990℃, 1010℃, 1030℃, 1050℃, etc.

[0035] It should be noted that the first sintering peak temperature is high because the P region has a low doping concentration and a large sheet resistance, and high temperature sintering is required to form a good ohmic contact.

[0036] As an optional embodiment, the time of the first sintering is 1-300s, for example, it can be 1s, 20s, 40s, 60s, 80s, 100s, 120s, 140s, 160s, 180s, 200s, 220s, 240s, 260s, 280s, 300s, etc.

[0037] As an optional embodiment, the peak temperature of the second sintering is 450-950℃, for example, it can be 450℃, 470℃, 490℃, 510℃, 530℃, 550℃, 570℃, 590℃, 610℃, 630℃, 650℃, 670℃, 690℃, 710℃, 730℃, 750℃, 770℃, 790℃, 810℃, 830℃, 850℃, 870℃, 890℃, 910℃, 930℃, 950℃, etc.

[0038] It should be noted that the second sintering peak temperature is lower because the N region has a high doping concentration, and a slightly lower sintering temperature can achieve a good ohmic contact.

[0039] As an optional embodiment, the time of the second sintering is 1-300s, for example, it can be 1s, 20s, 40s, 60s, 80s, 100s, 120s, 140s, 160s, 180s, 200s, 220s, 240s, 260s, 280s, 300s, etc.

[0040] As an optional embodiment, the peak temperature of the third sintering is 350-850℃, for example, it can be 350℃, 370℃, 390℃, 410℃, 430℃, 450℃, 470℃, 490℃, 510℃, 530℃, 550℃, 570℃, 590℃, 610℃, 630℃, 650℃, 670℃, 690℃, 710℃, 730℃, 750℃, 770℃, 790℃, 810℃, 830℃, 850℃, etc.

[0041] It should be noted that the third sintering temperature is relatively low because the main grid is used to collect current and does not need to be in contact with the silicon wafer, and high sintering temperature will affect the metal and semiconductor composite.

[0042] As an optional implementation, the second sintering time is 1-300s, for example, 1s, 20s, 40s, 60s, 80s, 100s, 120s, 140s, 160s, 180s, 200s, 220s, 240s, 260s, 280s, 300s, etc.

[0043] It should be noted that the peak temperature mentioned above is the actual measured temperature value of the furnace temperature instrument, not the display value of the sintering machine.

[0044] As an optional implementation, the line width of the P fine gate formed by the first sintering is 5-50μm, for example, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, etc.; the line height of the P fine gate is 1-20μm, for example, 1μm, 3μm, 5μm, 7μm, 9μm, 10μm, 11μm, 13μm, 15μm, 17μm, 19μm, 20μm, etc.; the spacing between two adjacent P fine gates is 200-4000μm, for example, 200μm, 400μm, 600μm, 800μm, 1000μm, 1200μm, 1400μm, 1600μm, 1800μm, 2000μm, 2200μm, 2400μm, 2600μm, 2800μm, 3000μm, 3200μm, 3400μm, 3600μm, 3800μm, 4000μm, etc.

[0045] As an optional implementation, the line width of the N fine gate formed by the second sintering is 5-50μm, for example, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, etc.; the line height of the N fine gate is 1-20μm, for example, 1μm, 3μm, 5μm, 7μm, 9μm, 10μm, 11μm, 13μm, 15μm, 17μm, 19μm, 20μm, etc.; the spacing between two adjacent N fine gates is 200-4000μm, for example, 200μm, 400μm, 600μm, 800μm, 1000μm, 1200μm, 1400μm, 1600μm, 1800μm, 2000μm, 2200μm, 2400μm, 2600μm, 2800μm, 3000μm, 3200μm, 3400μm, 3600μm, 3800μm, 4000μm, etc.

[0046] As an optional embodiment, the line width of the main grid formed by the third sintering is 20-200 μm, for example, it can be 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, 200 μm, etc., and the line height of the main grid is 1-20 μm, for example, it can be 1 μm, 3 μm, 5 μm, 7 μm, 9 μm, 10 μm, 11 μm, 13 μm, 15 μm, 17 μm, 19 μm, 20 μm, etc.

[0047] As an optional embodiment, the P-fine grid paste, N-fine grid paste and main grid paste are selected from any one or a combination of at least two of silver paste, aluminum paste, nickel paste or copper paste.

[0048] In a second aspect, the present application provides a solar cell prepared by the sintering method of the solar cell as described in the first aspect.

[0049] As an optional embodiment, the solar cell includes a TBC cell, a TOPCon cell, a PERC cell and other cells requiring high-temperature sintering.

[0050] As a preferred embodiment, the solar cell is a TBC cell.

[0051] As an optional embodiment, the cell piece to be printed in the present application is a semi-finished cell prepared by a previous process; wherein the previous process of the TBC cell includes: sequentially performing alkali etching, back surface deposition of a first tunneling oxide layer and a first intrinsic amorphous silicon layer, boron doping (the intrinsic amorphous silicon layer is converted into a polycrystalline silicon layer and forms a BSG layer), first patterning, cleaning, back surface deposition of a second tunneling oxide layer and a second intrinsic amorphous silicon layer, phosphorus doping (the intrinsic amorphous silicon layer is converted into a polycrystalline silicon layer and forms a PSG layer), second patterning, cleaning, texturing, back surface deposition of an AlO x layer, and double-sided deposition of a SiN x layer on the silicon wafer.

[0052] The present application will be further described below through specific examples and comparative examples, but it should be understood that these examples are only for more detailed description and should not be understood as limiting the present application in any form.

[0053] P-fine grid paste: supplier: Diko, model DK73K.

[0054] N-fine grid paste: supplier: Diko, model DK95H.

[0055] Main grid paste: supplier: Diko, model DK82B.

[0056] Example 1

[0057] The embodiment provides a TBC battery prepared by the following sintering method.

[0058] (a) printing P fine grid paste on a semi-finished battery piece by using a screen printing process, and performing first sintering; wherein the peak temperature of the first sintering is 800 DEG C; the time of the first sintering is 150 s; the line width of the P fine grid formed by the first sintering is 25 μm; the line height of the P fine grid is 10 μm; and the interval between two adjacent P fine grids is 2000 μm.

[0059] (b) printing N fine grid paste on the battery piece sintered in step (a) by using a screen printing process, and performing second sintering; wherein the peak temperature of the second sintering is 700 DEG C; the time of the second sintering is 150 s; the line width of the N fine grid formed by the second sintering is 25 μm; the line height of the N fine grid is 10 μm; and the interval between two adjacent N fine grids is 2000 μm.

[0060] (c) printing main grid paste on the battery piece sintered in step (b) by using a screen printing process, and performing third sintering; wherein the peak temperature of the third sintering is 600 DEG C; the time of the third sintering is 150 s; the line width of the main grid formed by the third sintering is 100 μm; and the line height of the main grid is 10 μm.

[0061] Embodiment 2

[0062] The embodiment provides a TBC battery prepared by the following sintering method.

[0063] (a) printing P fine grid paste on a semi-finished battery piece by using a screen printing process, and performing first sintering; wherein the peak temperature of the first sintering is 800 DEG C; the time of the first sintering is 10 s; the line width of the P fine grid formed by the first sintering is 5 μm; the line height of the P fine grid is 1 μm; and the interval between two adjacent P fine grids is 200 μm.

[0064] (b) printing N fine grid paste on the battery piece sintered in step (a) by using a screen printing process, and performing second sintering; wherein the peak temperature of the second sintering is 750 DEG C; the time of the second sintering is 10 s; the line width of the N fine grid formed by the second sintering is 5 μm; the line height of the N fine grid is 1 μm; and the interval between two adjacent N fine grids is 200 μm.

[0065] (c) printing main grid paste on the battery piece sintered in step (b) by using screen printing process, and performing third sintering; wherein the peak temperature of the third sintering is 700 ℃; the time of the third sintering is 10 s; the line width of the main grid formed by the third sintering is 20 μm; and the line height of the main grid is 1 μm.

[0066] Example 3

[0067] The embodiment provides a TBC battery prepared by the following sintering method.

[0068] (a) printing P fine grid paste on the semi-finished battery piece by using screen printing process, and performing first sintering; wherein the peak temperature of the first sintering is 1000 ℃; the time of the first sintering is 300 s; the line width of the P fine grid formed by the first sintering is 50 μm; the line height of the P fine grid is 20 μm; and the interval between two adjacent P fine grids is 4000 μm.

[0069] (b) printing N fine grid paste on the battery piece sintered in step (a) by using screen printing process, and performing second sintering; wherein the peak temperature of the second sintering is 800 ℃; the time of the second sintering is 300 s; the line width of the N fine grid formed by the second sintering is 50 μm; the line height of the N fine grid is 20 μm; and the interval between two adjacent N fine grids is 4000 μm.

[0070] (c) printing main grid paste on the battery piece sintered in step (b) by using screen printing process, and performing third sintering; wherein the peak temperature of the third sintering is 600 ℃; the time of the third sintering is 300 s; the line width of the main grid formed by the third sintering is 200 μm; and the line height of the main grid is 20 μm.

[0071] Example 4

[0072] The embodiment provides a TBC battery, which is different from the TBC battery in example 1 only in that the peak temperature of the first sintering is 720 ℃, the peak temperature of the second sintering is 700 ℃, and the peak temperature of the third sintering is 680 ℃, and the other steps are completely consistent with those in example 1.

[0073] Example 5

[0074] The embodiment provides a TBC battery, which is different from the TBC battery in example 1 only in that the peak temperature of the first sintering is 1050 ℃, the peak temperature of the second sintering is 750 ℃, and the peak temperature of the third sintering is 450 ℃, and the other steps are completely consistent with those in example 1.

[0075] Comparative Example 1

[0076] The present comparative example provides a TBC battery prepared by the following sintering method:

[0077] (a) The main grid slurry is first printed on the semi-finished battery sheet by using a screen printing process, and dried at 50°C for 200s; the line width of the main grid is 100μm; the line height of the main grid is 10μm.

[0078] (b) The N-fine grid slurry is printed on the battery sheet dried in step (a) by using a screen printing process, and dried at 50°C for 200s; the line width of the N-fine grid is 25μm; the line height of the N-fine grid is 10μm; the distance between two adjacent N-fine grids is 2000μm.

[0079] (c) The P-fine grid slurry is printed on the battery sheet dried in step (b) by using a screen printing process, and sintered at 700°C for 150s; the line width of the P-fine grid is 25μm; the line height of the P-fine grid is 10μm; the distance between two adjacent P-fine grids is 2000μm.

[0080] Comparative Example 2

[0081] The present comparative example provides a TBC battery, which is different from Example 1 in that the gradient sintering method is not used, and the peak temperature of the first sintering, the second sintering and the third sintering is 800°C, and other steps are completely consistent with Example 1.

[0082] Comparative Example 3

[0083] The present comparative example provides a TBC battery, which is different from Example 1 in that the gradient sintering method is not used, and the peak temperature of the first sintering, the second sintering and the third sintering is 700°C, and other steps are completely consistent with Example 1.

[0084] Comparative Example 4

[0085] The present comparative example provides a TBC battery, which is different from Example 1 in that the gradient sintering method is not used, and the peak temperature of the first sintering, the second sintering and the third sintering is 600°C, and other steps are completely consistent with Example 1.

[0086] Comparative Example 5

[0087] The present comparative example provides a TBC battery prepared by the following steps:

[0088] (a) The main grid slurry is first printed on the semi-finished battery sheet by using a screen printing process, and sintered for the first time; wherein the peak temperature of the first sintering is 600°C; the time of the first sintering is 100s; the line width of the main grid formed by the first sintering is 100μm; the line height of the main grid is 10μm.

[0089] (b) printing N fine grid paste on the sintered battery piece of step (a) by using a screen printing process, and performing second sintering; wherein the peak temperature of the second sintering is 700℃; the time of the second sintering is 100s; the line width of the N fine grid formed by the second sintering is 25μm; the line height of the N fine grid is 10μm; and the distance between two adjacent N fine grids is 2000μm.

[0090] (c) printing P fine grid paste on the sintered battery piece of step (a) by using a screen printing process, and performing third sintering; wherein the peak temperature of the third sintering is 800℃; the time of the third sintering is 1-300s; the line width of the P fine grid formed by the third sintering is 25μm; the line height of the P fine grid is 10μm; and the distance between two adjacent P fine grids is 2000μm.

[0091] Test Example 1

[0092] Test Method: 1000pcs of semi-finished battery pieces before screen printing were evenly divided into 10 groups, and each group was sintered by using the sintering method defined in corresponding Examples 1-5 and Comparative Examples 1-5, and finally the battery performance was tested.

[0093] The test results are shown in Table 1 below:

[0094] Table 1

[0095]

[0096]

[0097] As shown in Table 1, by using the technical solution of using different sintering temperatures for different printing areas, the contact effect of the metal and the silicon wafer in the P region, the N region and the main grid region is improved, and the solar cell efficiency is significantly improved by the metallization process described in the application.

[0098] As can be known from the comparison of Example 1 and Examples 4-5, the first sintering, the second sintering and the third sintering are performed by using gradient cooling sintering, and the temperature difference between each adjacent sintering is 50-250℃, if the temperature difference is too small or too large, the solar cell efficiency will be reduced.

[0099] As can be known from the comparison of Example 1 and Comparative Example 1, the problem of the TBC battery sintering process provided by Comparative Example 1 is that the sintering temperature required by the main grid paste, the N fine grid paste and the P fine grid paste is greatly different, at present, the three pastes are printed and then sintered uniformly, and it is difficult to ensure that the three pastes can achieve the optimal sintering effect by using the sintering temperature, and the contact effect of the metal and the silicon wafer in the P region, the N region and the main grid region is poor, which increases the recombination of the battery piece and reduces the photoelectric conversion efficiency of the battery piece.

[0100] From the comparison of Example 1 and Comparative Examples 2-4, it can be seen that sintering at a single temperature cannot ensure that all three pastes achieve optimal sintering results, and all will result in a decrease in the efficiency of the TBC battery.

[0101] From the comparison of Example 1 and Comparative Example 5, it can be seen that sintering according to the gradient temperature method of main grid-N fine grid-P fine grid, although it is according to the optimal sintering temperature of the three pastes, the metal and silicon wafer contact effect of the P region, N region and main grid region is poor, resulting in a decrease in the efficiency of the TBC battery.

[0102] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A sintering method for a solar cell, characterized in that: include: First, print the P fine grid paste on the cell and perform the first sintering; Then print the N fine grid slurry and perform the second sintering; Finally, the main grid paste is printed and sintered for the third time to obtain a solar cell.

2. The sintering method of a solar cell according to claim 1, characterized in that: The first sintering, the second sintering and the third sintering adopt a gradient cooling sintering method, and the temperature difference between each adjacent sintering is 50-250°C; Preferably, the temperature range of the first sintering, the second sintering and the third sintering is 1050-350°C.

3. The sintering method of a solar cell according to claim 2, characterized in that: The peak temperature of the first sintering is 550-1050° C.; and the time of the first sintering is 1-300 seconds.

4. The sintering method of a solar cell according to claim 2, characterized in that: The peak temperature of the second sintering is 450-950° C.; and the time of the second sintering is 1-300 seconds.

5. The sintering method of a solar cell according to claim 2, characterized in that: The peak temperature of the third sintering is 350-850° C.; and the time of the third sintering is 1-300 seconds.

6. The sintering method of a solar cell according to claim 1, characterized in that: The line width of the P fine gate formed by the first sintering is 5 to 50 μm; the line height of the P fine gate is 1 to 20 μm; and the distance between two adjacent P fine gates is 200 to 4000 μm.

7. The sintering method of a solar cell according to claim 1, characterized in that: The line width of the N fine grid formed by the second sintering is 5 to 50 μm; the line height of the N fine grid is 1 to 20 μm; and the distance between two adjacent N fine grids is 200 to 4000 μm.

8. The sintering method of a solar cell according to claim 1, characterized in that: The line width of the main grid formed by the third sintering is 20-200 μm, and the line height of the main grid is 1-20 μm.

9. The sintering method of a solar cell according to claim 1, characterized in that: The P fine grid paste, N fine grid paste and main grid paste are selected from any one of silver paste, aluminum paste, nickel paste and copper paste, or a combination of at least two of them.

10. A solar cell, characterized in that: The solar cell is prepared by the sintering method of a solar cell according to any one of claims 1 to 9; And / or, the solar cell includes any one of a TBC cell, a TOPCon cell or a PERC cell.

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