TOPCon solar cell and cell assembly

Abstract

The utility model relates to a TOPCon solar cell and a cell assembly, the back surface of a silicon substrate of the solar cell is provided with a plurality of removal parts and non-removal parts at intervals, and the non-removal parts are provided with back metal electrodes; the back metal electrode comprises a plurality of main grids which extend along the second direction on the back passivation layer and are arranged along the first direction; the distance M between the two adjacent main grids and the proportion P of the width of the non-removal part in the first direction to the distance between the two adjacent main grids meet the condition that P is larger than 5E-07M + 0.0127 and smaller than-5.6 E-06M + 0.1343. According to the utility model, the poly layer is removed by thinning the back part area which is not in contact with the metal electrode, and the proportion of the width of the N + area along the first direction to the distance between the main grids is limited, so that the light absorption problem caused by the over-thick poly layer can be reduced, and the excellent electrical performance of the cell can be ensured.

Description

Technical Field

[0001] This utility model relates to the field of solar cell technology, specifically to a TOPCon solar cell and battery module with good electrical performance. Background Technology

[0002] Tunnel oxide passivating contacts (TOPCon) solar cells are a type of solar cell that uses an ultrathin oxide layer as a passivation layer. In N-type TOPCon cells, the substrate is N-type Si. A P+ doped layer is obtained on the front side through boron diffusion, and an AlOx / SiNx passivation dielectric film is deposited on the front side using ALD or PECVD. On the back side, a tunnel oxide layer and polycrystalline silicon are deposited using LPCVD, and an N+ doped layer is obtained through in-situ p-doping or intrinsic p-diffusion. The metal electrodes on both sides are typically fabricated using screen printing.

[0003] However, current mainstream TOPCon solar cell fabrication technologies, in pursuit of high efficiency, generally employ the method of constructing a thicker poly layer. While a thicker poly layer helps improve cell performance to some extent, it also introduces problems such as excessively high optical parasitic absorption and current loss. Furthermore, the arrangement of the grid lines also affects cell performance. Utility Model Content

[0004] To address the aforementioned technical problems, this utility model provides a TOPCon solar cell and a battery module. The technical solution adopted by this utility model is as follows:

[0005] A TOPCon solar cell includes a silicon substrate, on the front side of the silicon substrate along a direction away from the silicon substrate, a boron doped layer, a front passivation layer, and a front metal electrode, the front metal electrode being in ohmic contact with the boron doped layer;

[0006] The back side of the silicon substrate is provided with a plurality of removal portions and non-removable portions at intervals along a first direction. The removal portions are provided with a back passivation layer. The non-removable portions are provided with a tunneling oxide layer, a conductive passivation layer, a back passivation layer, and a back metal electrode along a direction away from the silicon substrate. The back metal electrode is in ohmic contact with the conductive passivation layer.

[0007] The back metal electrode includes a plurality of main gates extending along a second direction and arranged along a first direction on the back passivation layer;

[0008] The TOPCon solar cell satisfies:

[0009] 5E-07M + 0.0127<P<-5.6E-06M + 0.1343;

[0010] Where M is the distance between two adjacent main gates, in μm;

[0011] P is the ratio of the width of the non-removed portion along the first direction to the distance between two adjacent main gates.

[0012] Furthermore, the distance M between two adjacent main gates and the ratio P of the width of the non-removed portion along the first direction to the distance between the two adjacent main gates satisfy the following: -5E-07M + 0.03299 < P < -4.6E-06M + 0.1140.

[0013] Furthermore, the width of the non-removed portion along the first direction is 1.8 to 7.8% of the distance between two adjacent main gates.

[0014] Furthermore, the width of the non-removed portion along the first direction is 3.2 to 6.7% of the distance between two adjacent main gates.

[0015] Furthermore, the distance M between two adjacent main gates is 7090~16800μm, and the width N of the non-removed portion along the first direction is 160~800μm.

[0016] Furthermore, the conductive passivation layer is a phosphorus-doped polycrystalline silicon layer or a phosphorus-doped stacked polycrystalline silicon layer containing a silicon oxide layer; the stacked polycrystalline silicon layer containing silicon oxide can be a polycrystalline silicon layer + silicon oxide layer + polycrystalline silicon layer structure.

[0017] On the other hand, the present invention also provides a battery assembly, including the aforementioned TOPCon solar cell.

[0018] Furthermore, the back metal electrode also includes a plurality of fine grids extending along a first direction and arranged along a second direction, wherein the intersections of the fine grids and the main grid are connected along the second direction by interconnecting strips.

[0019] Furthermore, the fine grid includes a first fine grid and a second fine grid that are disconnected along the first direction, and the main grid is distributed at intervals along the second direction, with the first fine grid and the second fine grid connected through the main grid.

[0020] Furthermore, the main gate includes a middle region and an end region, the first fine gate and the second fine gate are respectively connected to the two end regions of the main gate, and the width of the middle region along the second direction is greater than the width of the end regions.

[0021] The TOPCon solar cell of this invention removes the poly layer by thinning the back portion that is not in contact with the metal electrode, while limiting the ratio of the width of the non-removed portion (N+ region) in contact with the metal electrode along the first direction to the distance between two adjacent main grids. This controls the extent of poly layer thinning, which can improve the light transmittance of the solar cell, reduce the light absorption problem caused by excessive poly layer thickness, and ensure that the cell has excellent electrical performance. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the TOPCon solar cell structure of this utility model;

[0024] Figure 2 This is a partial structural diagram of the back of the TOPCon solar cell of this utility model (without interconnecting strips).

[0025] Figure 3 This is a partial structural diagram of the back of the TOPCon solar cell of this utility model (without interconnecting strips).

[0026] Figure 4 This is a partial structural diagram of the back of the battery module of this utility model (connecting interconnect strips);

[0027] Figure 5 This is a partial structural diagram of the back of the TOPCon solar cell of this utility model (without interconnecting strips).

[0028] In the figure: 1-Silicon substrate, 2-Boron doped layer, 3-Front passivation layer, 4-Front metal electrode, 5-Removed portion, 6-Non-removed portion, 7-Back passivation layer, 8-Tunneling oxide layer, 9-Conductive passivation layer, 10-Back metal electrode, 11-Main gate, 12-Fine gate, 13-First fine gate, 14-Second fine gate, 15-Intermediate region, 16-End region, 17-Interconnect strip. Detailed Implementation

[0029] The technical solutions of this utility model will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0030] In the expression of this invention, E represents the exponent in scientific notation, and the number following E represents a power of 10. For example, 5E-07 represents 0.0000005.

[0031] A type of TOPCon solar cell, such as Figure 1-2 As shown, it includes a silicon substrate 1, and a boron doped layer 2, a front passivation layer 3, and a front metal electrode 4 are disposed on the front side of the silicon substrate along the direction away from the silicon substrate. The front metal electrode 4 is in ohmic contact with the boron doped layer 2.

[0032] The back side of the silicon substrate 1 is provided with a plurality of removal portions 5 and non-removable portions 6 at intervals along the second direction. The removal portions 5 are provided with a back passivation layer 7. The non-removable portions 6 are provided with a tunneling oxide layer 8, a conductive passivation layer 9, a back passivation layer 7, and a back metal electrode 10 along the direction away from the silicon substrate 1. The back metal electrode 10 is in ohmic contact with the conductive passivation layer 9.

[0033] The back metal electrode 10 includes a plurality of main gates 11 extending along a second direction and arranged along a first direction on the back passivation layer 7;

[0034] The TOPCon solar cell satisfies:

[0035] 5E-07M + 0.0127<P<-5.6E-06M + 0.1343;

[0036] Where M is the distance between two adjacent main gates, in μm;

[0037] P is the ratio of the width of the non-removed portion along the first direction to the distance between two adjacent main gates.

[0038] This invention relates to a TOPCon solar cell. By thinning and removing the poly layer in the back portion that is not in contact with the metal electrode, and simultaneously limiting the ratio of the width of the non-removed portion (N+ region) in contact with the metal electrode along the first direction to the distance between adjacent main grids, this invention improves the light transmittance of the solar cell, reduces light absorption problems caused by excessive poly layer thickness, and ensures excellent electrical performance, thereby improving the cell's Jsc (Joint Score). Furthermore, the passivation film layer on the back has a higher passivation effect than the tunneling oxide layer + conductive passivation layer. Thinning and removing the poly layer in the back portion can improve the cell's Voc (Volume Occurrence), but to form a good PN junction, the non-removed portion cannot be too narrow, otherwise it will reduce electrical performance such as FF (Fast Forward). Excessively narrowing the width of the non-removed portion can also make the grid line area more prone to misalignment, making the cell more susceptible to leakage and increasing the defect rate in mass production. This invention, by limiting the width of the non-removed portion, optimizes cell performance while ensuring a high yield rate.

[0039] This utility model has a plurality of removal portions and non-removal portions spaced apart along a second direction, and also a plurality of removal portions and non-removal portions spaced apart along a first direction, wherein the non-removal portions along the first direction and the non-removal portions along the second direction intersect. The width of the non-removal portion along the first direction, as referred to in this utility model, is the width of the portion in the first direction that does not intersect with the non-removal portion along the second direction, i.e. Figure 1 In the figure, N represents the width; the width of the non-removed portion along the second direction refers to the width of the portion in the second direction that does not intersect with the non-removed portion along the first direction, i.e. Figure 1 The width is represented by Z.

[0040] Specifically, in some embodiments of this utility model, the distance M between two adjacent main gates and the ratio P of the width of the non-removed portion along the first direction to the distance between the two adjacent main gates satisfy the following: -5E-07M +0.03299 < P < -4.6E-06M + 0.1140.

[0041] Specifically, in some embodiments of this invention, the distance M between two adjacent main gates is 7090 μm to 16800 μm, the width of the non-removed portion along the first direction accounts for 1.8% to 7.8% of the distance between the two adjacent main gates, and the width of the non-removed portion along the first direction is 160 to 800 μm. Preferably, the width of the non-removed portion along the first direction accounts for 3.2% to 6.7% of the distance between the two adjacent main gates, and the width of the non-removed portion along the first direction is 260 to 650 μm.

[0042] Preferably, the distance M between two adjacent main gates is 9090μm or 10800μm.

[0043] When the distance M between two adjacent main gates is 9090 μm, the proportion P of the width of the non-removed portion along the first direction to the distance between the two adjacent main gates is 1.8 to 8.8%; the proportion P of the width of the non-removed portion along the first direction to the distance between the two adjacent main gates is 1.8%, 2.3%, 2.9%, 3.4%, 4.0%, 4.5.0%, 5.1%, 5.6%, 6.2%, 6.7%, 7.3%, 7.8% or any combination thereof; preferably, the proportion P of the width of the non-removed portion along the first direction to the distance between the two adjacent main gates is 2.9 to 6.7%.

[0044] When the distance M between two adjacent main gates is 10800 μm, the proportion P of the width of the non-removed portion along the first direction to the distance between the two adjacent main gates is 1.9% to 7.4%; specifically, the proportion P of the width of the non-removed portion along the first direction to the distance between the two adjacent main gates is 1.9%, 2.3%, 2.8%, 3.2%, 3.7%, 4.2%, 4.6%, 5.1%, 5.6%, 6.0%, 6.5%, 6.9%, 7.4%, or any combination of both; preferably, the proportion P of the width of the non-removed portion along the first direction to the distance between the two adjacent main gates is 2.8% to 6.0%.

[0045] Specifically, in some embodiments of this utility model, the back metal electrode further includes a plurality of fine grids extending along a first direction and arranged along a second direction, and the intersection positions of the fine grids and the main grid are connected along the second direction by interconnecting strips.

[0046] Specifically, in some embodiments of this invention, the distance X between two adjacent fine gates is 500 μm to 1300 μm, the proportion Y of the width of the non-removed portion along the second direction to the distance between two adjacent fine gates is 14.1% to 74.7%, and the width of the non-removed portion along the second direction is 130 to 720 μm. Preferably, the proportion Y of the width of the non-removed portion along the second direction to the distance between two adjacent fine gates is 27.8% to 58.2%, and the width of the non-removed portion along the second direction is 280 to 600 μm.

[0047] Specifically, in some embodiments of this utility model, such as Figure 3-4As shown, the fine grid 12 includes a first fine grid 13 and a second fine grid 14 that are disconnected along the first direction. The main grid is spaced apart along the second direction. The first fine grid 13 and the second fine grid 14 are connected through the main grid 11. The distance c between the first fine grid 13 and the second fine grid 14 is less than the width b of the interconnecting strip 17 at the contact position with the first fine grid and the second fine grid. By disconnecting the main grid along the second direction and the fine grid along the first direction, the amount of grid wire paste is reduced while ensuring transmission effect, which helps to reduce costs.

[0048] Specifically, in some embodiments of this utility model, such as Figure 5 As shown, the main grid 11 includes a middle region 15 and an end region 16. The first fine grid 13 and the second fine grid 14 are respectively connected to the two end regions 16 of the main grid 11. The width of the middle region 15 along the second direction is greater than the width of the end regions 16. By dividing the end and middle regions of the main grid into different widths, sufficient contact with the interconnecting strip can be achieved, while reducing the consumption of grid line paste.

[0049] Specifically, in some embodiments of this utility model, the distance between the first fine grid and the second fine grid is 0.1~2mm.

[0050] Specifically, in some embodiments of this utility model, the length of the main grid along the first direction is 150 to 400% of the width of the interconnecting strip.

[0051] Specifically, in some embodiments of this utility model, the width of the main gate along the second direction is 120 to 700% of the width of the fine gate along the second direction.

[0052] Specifically, in some embodiments of this utility model, the conductive passivation layer is a phosphorus-doped polycrystalline silicon layer or a phosphorus-doped stacked polycrystalline silicon layer containing silicon oxide; preferably, the conductive passivation layer is a phosphorus-doped polycrystalline silicon layer.

[0053] The present invention will be further described below with reference to specific embodiments.

[0054] Example 1

[0055] This embodiment provides a TOPCon solar cell and battery module, such as Figure 1-3 As shown, it includes a silicon substrate 1, and a boron doped layer 2, a front passivation layer 3, and a front metal electrode 4 are disposed on the front side of the silicon substrate along the direction away from the silicon substrate. The front metal electrode 4 is in ohmic contact with the boron doped layer 2.

[0056] The back side of the silicon substrate 1 is provided with a plurality of removal portions 5 and non-removal portions 6 at intervals along a first direction. The removal portions 5 are provided with a back passivation layer 7. The non-removal portions 6 are provided with a tunneling oxide layer 8, a doped polysilicon layer 9, a back passivation layer 7, and a back metal electrode 10 along a direction away from the silicon substrate 1. The back metal electrode 10 is in ohmic contact with the doped polysilicon layer 9.

[0057] The back metal electrode 10 includes a plurality of fine gates disposed on the back passivation layer 7 along a first direction and a plurality of main gates 11 arranged perpendicular to the fine gates along a second direction. The intersections of the fine gates and the main gates 11 are connected along the second direction by interconnecting strips 12.

[0058] The distance X between two adjacent fine gates is 1065 μm, the width Z of the non-removable portion along the second direction is 450 μm, and the ratio Y of the width of the non-removable portion along the second direction to the distance between two adjacent fine gates is 42.3%. The distance M between two adjacent main gates is 10800 μm, the width N of the non-removable portion along the first direction is 800 μm, and the ratio P of the width of the non-removable portion along the first direction to the distance between two adjacent main gates is 7.4%.

[0059] Examples 2-25, Comparative Examples 1-5

[0060] Examples 2-25 and Comparative Examples 1-5 differ from Example 1 only in the distance between two adjacent main gates, and the proportion of the width of the non-removed portion along the first direction to the distance between two adjacent main gates, as shown in Table 1. The rest is the same as Example 1, and the test results are shown in Table 1.

[0061] Table 1

[0062] Group Main gate pitch M / μm Non-removable part width N / μm P Voc(mV) <![CDATA[Jsc(mA / cm 2 )]]> FF(%) Eta(%) Example 1 10800 800 7.4% 728.520 41.450 83.621 25.251 Example 2 10800 750 6.9% 728.607 41.450 83.621 25.254 Example 3 10800 700 6.5% 728.695 41.450 83.617 25.256 Example 4 10800 650 6.0% 728.782 41.450 83.615 25.259 Example 5 10800 600 5.6% 728.870 41.450 83.613 25.261 Example 6 10800 550 5.1% 728.957 41.451 83.612 25.264 Example 7 10800 500 4.6% 729.030 41.451 83.610 25.266 Example 8 10800 450 4.2% 729.103 41.451 83.608 25.268 Example 9 10800 400 3.7% 729.176 41.451 83.599 25.268 Example 10 10800 350 3.2% 729.249 41.451 83.582 25.265 Example 11 10800 300 2.8% 729.322 41.451 83.545 25.256 Example 12 10800 250 2.3% 729.395 41.446 83.532 25.252 Example 13 10800 200 1.9% 729.468 41.442 83.520 25.249 Example 14 9090 710 7.8% 729.534 42.043 83.846 25.717 Example 15 9090 660 7.3% 729.644 42.043 83.837 25.718 Example 16 9090 610 6.7% 729.753 42.043 83.829 25.719 Example 17 9090 560 6.2% 729.863 42.043 83.820 25.721 Example 18 9090 510 5.6% 729.972 42.043 83.812 25.722 Example 19 9090 460 5.1% 730.082 42.043 83.804 25.724 Example 20 9090 410 4.5% 730.191 42.043 83.795 25.725 Example 21 9090 360 4.0% 730.301 42.044 83.787 25.726 Example 22 9090 310 3.4% 730.410 42.044 83.770 25.725 Example 23 9090 260 2.9% 730.520 42.044 83.737 25.719 Example 24 9090 210 2.3% 730.629 42.039 83.713 25.713 Example 25 9090 160 1.8% 730.739 42.035 83.688 25.706 Comparative Example 1 10800 150 1.4% 729.030 41.069 82.936 24.832 Comparative Example 2 10800 100 0.9% 728.374 40.741 82.355 24.438 Comparative Example 3 9090 760 8.4% 729.425 42.043 83.846 25.713 Comparative Example 4 9090 110 1.2% 730.301 41.657 83.102 25.281 Comparative Example 5 9090 60 0.7% 729.643 41.324 82.520 24.881

[0063] As can be seen from the test results in Table 1, the TOPCon solar cell of this invention can improve the light transmittance of the solar cell, reduce the light absorption problem caused by excessive poly layer thickness, and ensure that the cell has excellent electrical performance by thinning and removing the area on the back of the silicon substrate that is not in contact with the metal electrode, and controlling the main grid spacing and the width of the non-removed part along the first direction.

[0064] The present invention has been further described above with reference to specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the substance and scope of the present invention. Various modifications made by those skilled in the art to the above embodiments after reading this specification are all within the scope of protection of the present invention.

Claims

1. A TOPCon solar cell, comprising a silicon substrate, wherein a boron-doped layer, a front passivation layer, and a front metal electrode are disposed on the front side of the silicon substrate along a direction away from the silicon substrate, and the front metal electrode is in ohmic contact with the boron-doped layer; characterized in that: The back side of the silicon substrate is provided with a plurality of removal portions and non-removable portions at intervals along the second direction. The removal portions are provided with a back passivation layer. The non-removable portions are provided with a tunneling oxide layer, a conductive passivation layer, a back passivation layer, and a back metal electrode along the direction away from the silicon substrate. The back metal electrode is in ohmic contact with the conductive passivation layer. The back metal electrode includes a plurality of main gates extending along a second direction and arranged along a first direction on the back passivation layer; The TOPCon solar cell satisfies: 5E-07M + 0.0127<P<-5.6E-06M + 0.1343; Where M is the distance between two adjacent main gates, in μm; P is the ratio of the width of the non-removed portion along the first direction to the distance between two adjacent main gates.

2. The TOPCon solar cell according to claim 1, characterized in that, The distance M between two adjacent main gates and the ratio P of the width of the non-removed portion along the first direction to the distance between the two adjacent main gates satisfy the following: -5E-07M + 0.03299 < P < -4.6E-06M + 0.1140.

3. The TOPCon solar cell according to claim 1, characterized in that, The width of the non-removed portion along the first direction is 1.8 to 7.8% of the distance between two adjacent main gates.

4. The TOPCon solar cell according to claim 1, characterized in that, The width of the non-removed portion along the first direction is 3.2 to 6.7% of the distance between two adjacent main gates.

5. The TOPCon solar cell according to claim 1, characterized in that, The distance M between two adjacent main gates is 7090~16800μm, and the width N of the non-removed portion along the first direction is 160~800μm.

6. The TOPCon solar cell according to claim 1, characterized in that, The conductive passivation layer is a phosphorus-doped polycrystalline silicon layer.

7. The TOPCon solar cell according to claim 1, characterized in that, The conductive passivation layer is a phosphorus-doped stacked polycrystalline silicon layer containing a silicon oxide layer.

8. A battery assembly, characterized in that, Includes the TOPCon solar cell according to any one of claims 1-7.

9. The battery assembly according to claim 8, characterized in that, The back metal electrode also includes a plurality of fine grids extending along a first direction and arranged along a second direction, wherein the intersections of the fine grids and the main grid are connected along the second direction by interconnecting strips.

10. The battery assembly according to claim 9, characterized in that, The fine grid includes a first fine grid and a second fine grid that are disconnected along a first direction, and the main grid is distributed at intervals along a second direction, with the first fine grid and the second fine grid connected through the main grid.

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