Back contact solar cell, photovoltaic module and photovoltaic system

Abstract

The invention is suitable for the technical field of solar cells, and provides a back contact solar cell, comprising: a silicon wafer, the back of which is provided with an edge main grid and a middle main grid adjacent to the edge main grid; the first fine grid lines are arranged on the edge main grids; the second fine grid lines are arranged on the middle main grid; each first fine grid line comprises a first edge fine grid and a second edge fine grid, one of the first edge fine grid and the second edge fine grid is an unequal-width section, the other one of the first edge fine grid and the second edge fine grid is an equal-width section, the width of the equal-width section is larger than or equal to that of the second fine grid line, and the average width of the unequal-width sections is larger than that of the equal-width section. According to the invention, the width of the first fine grid line is set to be greater than the width of the second fine grid line, so that the carrier collection capability of the first fine grid line is improved, the contact resistance or series resistance of the metal grid line and the silicon wafer is reduced, the binding force of the metal grid line and the silicon wafer is improved, and the working efficiency of the cell is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular, to a back-contact solar cell, a photovoltaic module, and a photovoltaic system. Background Art

[0002] The grid lines of a solar cell are responsible for leading the photo-generated current in the cell body to the outside of the cell. The purpose of optimizing the grid line design is to minimize the series resistance of the cell, thereby reducing power loss and improving the working efficiency of the cell.

[0003] In some current solar cells, the width of the edge grid lines is the same as that of the center grid lines. However, there are often phenomena such as uneven or incomplete passivation film layers, uneven doping concentrations, or uneven edge morphologies at the edges of the cells, resulting in more edge defects. The same width of the center grid lines and the edge grid lines makes the edge carrier collection ability lower, which is not conducive to improving the working efficiency of the cell.

[0004] Therefore, there are defects in the prior art and improvements are needed. Summary of the Invention

[0005] The present invention provides a back-contact solar cell to solve the problem that in some current solar cells, the width of the edge grid lines is the same as that of the center grid lines. However, there are often phenomena such as uneven or incomplete passivation film layers, uneven doping concentrations, or uneven edge morphologies at the edges of the cells, resulting in more edge defects. The same width of the center grid lines and the edge grid lines makes the edge carrier collection ability lower, which is not conducive to improving the working efficiency of the cell.

[0006] In a first aspect, the present invention provides a back-contact solar cell, comprising:

[0007] a silicon wafer, on the back surface of which an edge main grid and an intermediate main grid adjacent to the edge main grid are provided;

[0008] a first fine grid line disposed on the edge main grid;

[0009] a second fine grid line disposed on the intermediate main grid;

[0010] The first fine grid line includes a first edge fine grid and a second edge fine grid. One of the first edge fine grid and the second edge fine grid is an unequal-width section, and the other is an equal-width section. The width of the equal-width section is greater than or equal to that of the second fine grid line, and the average width of the unequal-width section is greater than the width of the equal-width section.

[0011] In the embodiment of the present invention, by setting the width of the first fine grid line as a whole to be greater than the width of the second fine grid line, the carrier collection ability of the first fine grid line is improved, the contact resistance or series resistance between the metal grid line and the silicon wafer is reduced, the bonding force between the two is enhanced, the working efficiency of the battery is improved, and at the same time, the bonding force and mechanical strength between the edge metal and the silicon wafer are increased, the manufacturing defect rate of the battery chip is reduced, and the reliability of the battery chip is improved; the width of the equal-width section is greater than or equal to that of the second fine grid line, and the average width of the non-equal-width section is greater than the width of the equal-width section, so that the average width of the first fine grid line is greater than that of the second fine grid line. And because the first fine grid line is designed to include an equal-width section and a non-equal-width section, compared with the case where all are designed as non-equal-width sections, such a design makes it not all dimensions are greater than the second fine grid line, saving part of the material cost of the first fine grid line while increasing the width and carrier collection ability.

[0012] Preferably, the first edge fine grid is a non-equal-width section, the second edge fine grid is an equal-width section, and the first edge fine grid is respectively connected to the edge main grid and the second edge fine grid.

[0013] In the embodiment of the present invention, by designing the first edge fine grid as a non-equal-width section and the second edge fine grid as an equal-width section, compared with the case where the first fine grid line is all designed as an equal-width section, the non-equal-width section can be used to improve the carrier collection ability and better balance the resistance of the battery.

[0014] Preferably, the overall area of the first fine grid line is greater than 0.108 cm 2 .

[0015] In the embodiment of the present invention, by designing the overall area of the first fine grid line to be greater than 0.108 cm2, the overall area of the first fine grid line is larger, greater than the case where the first fine grid line is all of equal width, and the carrier collection ability is improved.

[0016] Preferably, the first edge fine grid is a width-gradual change section, and the width gradually decreases from the width at the end close to the edge main grid to the width at the end of the second edge fine grid until it is consistent with the width of the second edge fine grid.

[0017] In the embodiment of the present invention, by designing the first edge fine grid as a width-gradual change section, and the width gradually decreases from the width at the end close to the edge main grid to the width at the end of the second edge fine grid until it is consistent with the width of the second edge fine grid, the carrier collection ability of the first fine grid line is greater than that of the second fine grid line, which is beneficial to improving the working efficiency of the battery.

[0018] Preferably, the first edge fine grid is an equal-width section, the second edge fine grid is a non-equal-width section, and the first edge fine grid is respectively connected to the edge main grid and the second edge fine grid.

[0019] In the embodiment of the present invention, by designing the first edge fine grid as an equal-width section and the second edge fine grid as a non-equal-width section, compared with the case where all the first fine grid lines are designed as equal-width sections, the non-equal-width section can be used to improve the carrier collection ability and better balance the resistance of the battery.

[0020] Preferably, the overall area of the first fine grid line is greater than 0.108 cm 2 .

[0021] In the embodiment of the present invention, by designing the overall area of the first fine grid line to be greater than 0.108 cm 2 , the overall area of the first fine grid line is relatively large, larger than the case where all the first fine grid lines are equal-width sections, thus improving the carrier collection ability.

[0022] Preferably, the second edge fine grid is a width-gradual change section, and the width of the second edge fine grid gradually decreases from the width near one end of the second fine grid line to the width near one end of the first edge fine grid until it is consistent with the width of the first edge fine grid.

[0023] In the embodiment of the present invention, by designing the second edge fine grid as a width-gradual change section, and the width of the second edge fine grid gradually decreases from the width near one end of the second fine grid line to the width near one end of the first edge fine grid until it is consistent with the width of the first edge fine grid, the carrier collection ability of the first fine grid line is greater than that of the second fine grid line, which is beneficial to improving the working efficiency of the battery.

[0024] Preferably, the shape of the top view of the first edge fine grid or the second edge fine grid is one of a trapezoid and an irregular quadrilateral.

[0025] In the embodiment of the present invention, by designing the shape of the top view of the first edge fine grid or the second edge fine grid to be one of a trapezoid and an irregular quadrilateral, when one of the first edge fine grid and the second edge fine grid is a non-equal-width section, the shape of the top view is a trapezoid or an irregular quadrilateral. Designing the non-equal-width section as a trapezoid or an irregular quadrilateral is beneficial to improving the carrier collection ability and reducing the resistance of the battery.

[0026] Preferably, when the shape of the top view of the first edge fine grid is a trapezoid, the base angle of the trapezoid is set to 20 degrees to 90 degrees; or

[0027] When the shape of the top view of the second edge fine grid is a trapezoid, the base angle of the trapezoid is set to 20 degrees to 90 degrees.

[0028] Preferably, when the shape of the top view of the first edge fine grid is a trapezoid, the length of the upper base of the trapezoid is greater than or equal to 10 microns, and the length of the lower base of the trapezoid is less than or equal to 250 microns; or

[0029] When the top view of the second edge fine grid is trapezoidal, the length of the upper base of the trapezoid is greater than or equal to 10 microns, and the length of the lower base of the trapezoid is less than or equal to 250 microns.

[0030] By reasonably setting the base angle of the trapezoid, the length of the upper base and the length of the lower base, the embodiments of the present invention are beneficial to improving the carrier collection ability and reducing the resistance of the battery.

[0031] Preferably, when the first edge fine grid is a non-uniform width section, the two side lines in its extending direction are straight lines, broken lines, curves or a combination of straight lines and curves; or

[0032] When the second edge fine grid is a non-uniform width section, the two side lines in its extending direction are straight lines, broken lines, curves or a combination of straight lines and curves.

[0033] By designing the two side lines of the non-uniform width section in its extending direction as straight lines, broken lines, curves or a combination of straight lines and curves, and by designing the two side lines of the non-uniform width section as various lines, the present invention embodiments can change the area ratio of the non-uniform width section, make the area ratio of the non-uniform width section better meet the actual requirements, balance the carrier collection ability, and reduce leakage.

[0034] Preferably, when the first edge fine grid is a non-uniform width section and the second edge fine grid is a uniform width section, the length ratio of the first edge fine grid to the second edge fine grid is 0.02 - 10; or

[0035] When the first edge fine grid is a uniform width section and the second edge fine grid is a non-uniform width section, the length ratio of the second edge fine grid to the first edge fine grid is 0.02 - 10.

[0036] By setting the length ratio of the non-uniform width section to the uniform width section to 0.02 - 10, the embodiments of the present invention can reduce battery leakage, improve the carrier collection ability within a reasonable range of the lengths of the non-uniform width and uniform width sections, and avoid frequent battery leakage and poor carrier collection ability caused by unreasonable length design of the two.

[0037] Preferably, when the first edge fine grid or the second edge fine grid is a non-uniform width section, the grid line width range is 10 - 250 microns.

[0038] Preferably, when the first edge fine grid or the second edge fine grid is a uniform width section, the grid line width range is 10 - 250 microns.

[0039] Preferably, when the first edge fine grid is a non-uniform width section and the second edge fine grid is a uniform width section, the ratio of the width of the first edge fine grid near the edge main grid to the width of the first edge fine grid near the second edge fine grid is greater than or equal to 1.2 times; or

[0040] When the first edge fine grid is a uniform width section and the second edge fine grid is a non-uniform width section, the ratio of the width of the second edge fine grid near the middle main grid to the width of the second edge fine grid near the first edge fine grid is greater than or equal to 1.2 times.

[0041] In the embodiment of the present invention, by designing the width ratio of the non-uniform width section and the uniform width section to be greater than or equal to 1.2 times, when the non-uniform width section is located in the edge region of the battery, the carrier collection ability of the edge region can be improved, the battery resistance can be reduced, and the working efficiency of the battery can be improved. When the non-uniform width section is located in the middle region of the battery, the carrier collection ability of the middle region can be improved, the battery resistance can be reduced, and the working efficiency of the battery can be improved.

[0042] Preferably, the height ratio of the first fine grid line and the second fine grid line is greater than or equal to 0.8 times.

[0043] In the embodiment of the present invention, by setting the height ratio of the first fine grid line and the second fine grid line to be greater than or equal to 0.8 times, the cross-sectional area of the first fine grid line is larger than that of the second fine grid line. Since the higher the height of the grid line, the larger the cross-sectional area of the grid line, the smaller the resistance of the grid line, and the smaller the series resistance, the higher the fill factor and the output power. Therefore, by reasonably setting the height ratio of the first fine grid line and the second fine grid line, the resistance of the grid line can be reduced, and the carrier collection ability and the output power of the battery can be improved.

[0044] Preferably, the length ratio of the first fine grid line and the second fine grid line is 1.2 - 2.0.

[0045] In the embodiment of the present invention, by setting the length ratio of the first fine grid line and the second fine grid line to be 1.2 - 2.0, the carrier collection ability and the resistance of the grid line can be better balanced.

[0046] Preferably, a plurality of pad points are provided on the edge main grid and the middle main grid, and the plurality of pad points are arranged at intervals along the length direction of the edge main grid and the middle main grid.

[0047] Preferably, the widths of the edge main grid and the middle main grid gradually decrease from the position near the pad points along the position away from the pad points.

[0048] In the embodiment of the present invention, the widths of the edge main grid and the middle main grid gradually decrease from the position close to the pad point along the position away from the pad point, and the stability of the connection between the edge main grid and the middle main grid and the pad point can be ensured. Moreover, since the width of the main grid gradually decreases, it is beneficial to reduce costs. For the TBC solar cell, the poly layer directly below the tapered main grid can be correspondingly designed with a tapered width to reduce the area of the poly layer occupying the silicon wafer, reduce the parasitic absorption of sunlight by the poly layer, increase the light absorption and utilization rate of the back cell, thereby improving the efficiency of the battery and the module and the power generation capacity of the back of the battery.

[0049] Preferably, the width range of the edge main grid is 25 - 1200 microns.

[0050] Preferably, the width range of the middle main grid is 25 - 1200 microns.

[0051] Preferably, the shape of the pad point is at least one of a rectangle, a polygon, and a circle.

[0052] Optionally, the width of the edge main grid is at least greater than the width of one of the pad points.

[0053] In the embodiment of the present invention, designing the width of the edge main grid to be at least greater than the width of one of the pad points is beneficial to reducing the resistance of the battery and improving the carrier collection ability.

[0054] Optionally, cross-shaped short and thin grid lines are provided at the position of the pad point close to the edge main grid.

[0055] In the embodiment of the present invention, providing cross-shaped short and thin grid lines at the position of the pad point close to the edge main grid is beneficial to current conduction.

[0056] Optionally, at least one of the ratio of the average width of the first thin grid line to the average width of the second thin grid line and the ratio of the average width of the edge main grid to the average width of the middle main grid is greater than 1.2.

[0057] Optionally, at least one of the ratio of the maximum width of the first thin grid line to the maximum width of the second thin grid line and the ratio of the maximum width of the edge main grid to the maximum width of the middle main grid is greater than 1.2.

[0058] In the embodiment of the present invention, by designing the ratio of the average width or the maximum width of the first thin grid line and the second thin grid line or the ratio of the average width or the maximum width of the edge main grid and the middle main grid to be greater than or equal to 1.2 times, the carrier collection ability of the first thin grid line and the edge main grid is stronger than that of the second thin grid line and the middle main grid.

[0059] Optionally, the area ratio of the first fine grid line to the second fine grid line is greater than 1.2.

[0060] Optionally, the area ratio range of the first fine grid line to the second fine grid line is 1.3 - 2.5.

[0061] Optionally, the overall area range of the second fine grid line is 0.09 - 15 cm 2 。

[0062] In the embodiment of the present invention, by designing the area ratio of the first fine grid line to the second fine grid line within a reasonable range, the overall area of the first fine grid line is larger than that of the second fine grid line, improving the carrier collection ability, enhancing the bonding ability between the first fine grid and the silicon wafer, and improving the reliability of the solar cell.

[0063] In a second aspect, the present invention provides a photovoltaic module, including the solar cell according to any one of the first aspects above.

[0064] In a third aspect, the present invention provides a photovoltaic system, including the photovoltaic module according to any one of the second aspects above. Description of the Drawings

[0065] The drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present invention and, together with the specification, are used to explain the principles of the present invention.

[0066] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0067] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements, unless otherwise stated, and the drawings in the figures do not constitute a proportional limitation.

[0068] Figure 1 It is a schematic plan view of a back-contact solar cell provided by an embodiment of the present invention.

[0069] Figure 2 For Figure 1 The enlarged sketch at A in

[0070] Figure 3 It is a schematic plan view of a first fine grid line provided by an embodiment of the present invention.

[0071] Figure 4Schematic diagram of the planar structure of the edge main grid provided by the embodiment of the present invention.

[0072] Description of the reference numerals in the drawings:

[0073] 1. silicon wafer; 2. edge main grid; 3. intermediate main grid; 4. first fine grid line; 5. second fine grid line; 6. first edge fine grid; 7. second edge fine grid; 8. pad point; 9. short fine grid line. Detailed implementation manners

[0074] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0075] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or letters in different examples. This repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0076] For ease of description, spatially relative relationship terms may be used in the text to describe the relative position relationship or movement of one element or feature shown in the figure relative to another element or feature. These relative relationship terms such as "inside", "outside", "inner side", "outer side", "below", "beneath", "above", "upper", "front", "rear", etc. This spatially relative relationship term is intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figure. For example, if the device in the figure undergoes a position flip or attitude change or movement state change, then these directional indications will change accordingly. For example, an element described as "below other elements or features" or "beneath other elements or features" will then be oriented as "above other elements or features" or "on other elements or features". Therefore, the example term "below..." may include the orientations of above and below. The device may be oriented otherwise (rotated 90 degrees or in other directions) and the spatially relative relationship descriptors used in the text are interpreted accordingly.

[0077] To solve the technical problems in the prior art, in the present invention, the width of the first fine grid line 4 is integrally set to be greater than the width of the second fine grid line 5, which improves the carrier collection ability of the first fine grid line 4, reduces the contact resistance or series resistance between the metal grid line and the silicon wafer, enhances the bonding force between the two, improves the working efficiency of the battery, and at the same time improves the bonding ability between the first fine grid line 4 and the silicon wafer to ensure the reliability of the battery cell; the width of the equal-width section is greater than or equal to that of the second fine grid line 5, and the average width of the non-equal-width section is greater than the width of the equal-width section, so that the average width of the first fine grid line 4 is greater than that of the second fine grid line 5. And since the first fine grid line 4 is provided with an equal-width section and a non-equal-width section, compared with the design of all non-equal-width sections, such a design makes it so that not all dimensions are greater than those of the second fine grid line 5, saving part of the material cost of the first fine grid line 4 while increasing the width and carrier collection ability.

[0078] Figures 1-4 A back-contact solar cell provided by an embodiment of the present invention includes:

[0079] A silicon wafer 1, on the back surface of the silicon wafer 1, an edge main grid 2 and an intermediate main grid 3 adjacent to the edge main grid 2 are provided;

[0080] A first fine grid line 4 disposed on the edge main grid 2;

[0081] A second fine grid line 5 disposed on the intermediate main grid 3;

[0082] Wherein, the first fine grid line 4 includes a first edge fine grid 6 and a second edge fine grid 7, one of the first edge fine grid 6 and the second edge fine grid 7 is a non-equal-width section, and the other is an equal-width section, the width of the equal-width section is greater than or equal to that of the second fine grid line 5, and the average width of the non-equal-width section is greater than the width of the equal-width section.

[0083] In the embodiment of the present invention, the silicon wafer 1 can be a P-type silicon wafer 1 or an N-type silicon wafer 1. The silicon wafer 1 can be a single-crystalline silicon wafer, which is a single crystal formed by slowly cooling molten silicon raw materials. The crystal structure is closely ordered, with high conductivity, conversion efficiency, stability and lifespan. It can also be a polycrystalline silicon wafer, which is a form of elemental silicon. When molten elemental silicon solidifies under supercooled conditions, silicon atoms are arranged in a diamond lattice form to form many crystal nuclei. If these crystal nuclei grow into grains with different crystal plane orientations, then these grains combine to form polycrystalline silicon. The surface of the silicon wafer 1 can be a polished surface or a textured surface, without limitation. There is no limitation in the present invention; preferably, the first fine grid line 4 and the second fine grid line 5 can be silver grid lines, aluminum grid lines, silver-aluminum grid lines, silver-coated copper grid lines, electroplated copper-tin grid lines or copper grid lines. The grid line composition can be one or more of nickel, copper, aluminum, tin, indium, cerium, and titanium. Among them, the number of the first fine grid line 4 can be one or more, and the number of the second fine grid line 5 can be one or more.

[0084] In the embodiment of the present invention, the width range of the edge main grid 2 in the X-axis direction is 25 - 1200 microns, and the width range of the middle main grid 3 in the X-axis direction is 10 - 1200 microns. Setting the width size ranges of the edge main grid 2 and the middle main grid 3 to be larger can be suitable for different widths of the edge main grid 2 and the middle main grid 3. In some embodiments, the width of the middle main grid 3 can be set to 600 microns, and the width of the edge main grid 2 can be set to 750 - 800 microns, such as 750 microns, 780 microns, 800 microns, which can ensure the optimal performance of the battery cell; when the first edge fine grid 6 is a non-uniform width section and the second edge fine grid 7 is a uniform width section, or when the second edge fine grid 7 is a non-uniform width section and the first edge fine grid 6 is a uniform width section, the overall area of the first fine grid line 4 is greater than 0.108 cm2. In some embodiments, the overall area of the first fine grid line 4 can be designed to be 0.108 cm 2 -17 cm 2 , for example, it can be 0.108 cm 2 , 0.2 cm 2 , 0.3 cm 2 , 5 cm 2 , 10 cm 2 , 15 cm 2 , 17 cm 2 etc. The present invention does not limit this. The overall area range of the second fine grid line 5 is 0.09 - 15 cm 2 , for example, it can be 0.09 cm 2 , 0.2 cm 2 , 0.3 cm 2 , 5 cm 2 , 10 cm 2 , 15 cm 2 etc. The present invention does not limit this.

[0085] In some embodiments, the first edge fine grid 6 is a non-uniform width section, the second edge fine grid 7 is a uniform width section, and the first edge fine grid 6 is respectively connected to the edge main grid 2 and the second edge fine grid 7; by designing the first edge fine grid 6 as a non-uniform width section and the second edge fine grid 7 as a uniform width section, compared with designing the entire first fine grid line 6 as a uniform width section, the non-uniform width section can be used to improve the carrier collection ability, reduce the grid line resistance and resistance loss, and better disperse the stress of the edge solder strip, improve the bonding force between the electrode and the silicon wafer 1, and improve the reliability of the battery cell.

[0086] Moreover, the overall width of the first fine grid line 4 is greater than that of the second fine grid line 5. In this way, it is beneficial to improve the carrier collection ability of the first fine grid line 4, enhance the bonding ability between the electrode and the silicon wafer, and is conducive to improving the working efficiency and reliability of the battery. The width of the equal-width section is greater than or equal to that of the second fine grid line 5, and the average width of the non-equal-width section is greater than that of the equal-width section. When the average width of the first fine grid line 4 is greater than that of the second fine grid line 5, not all dimensions of the first fine grid line 4 are greater than those of the second fine grid line 5. While increasing the width and carrier collection ability, part of the material cost of the first fine grid line 4 is saved. Compared with the case where the width of each dimension of the first fine grid line 4 is greater than that of the second fine grid line 5, the width of the equal-width section in this embodiment can be the same as that of the second fine grid line 5, and the first fine grid line 4 in this embodiment is not prone to leakage.

[0087] In addition, since the width of the grid line determines the cross-sectional area of the grid line, which affects the resistance and light-shielding loss of the grid line. The smaller the width of the grid line, the smaller the cross-sectional area of the grid line, the greater its resistance, and the lower the fill factor and output power. Therefore, in the embodiment of the present invention, controlling the widths of the first fine grid line 4 and the second fine grid line 5 within a reasonable range is beneficial to reducing the battery resistance and increasing the fill factor and output power.

[0088] As an embodiment of the present invention, when the first edge fine grid 6 is a non-equal-width section and the second edge fine grid 7 is an equal-width section, the ratio of the width of the first edge fine grid 6 near the edge main grid 2 to the width of the first edge fine grid 6 near the second edge fine grid 7 is greater than or equal to 1.2 times.

[0089] Among them, the ratio of the width of the first edge fine grid 6 near the edge main grid 2 to the width of the first edge fine grid 6 near the second edge fine grid 7 can be 1.2 times, 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times or greater, and can be specifically determined in combination with the size of the silicon wafer 1 and the actual number of the first fine grid lines 4 provided. In some specific embodiments, when the ratio of the width of the first edge fine grid 6 near the edge main grid 2 to the width of the first edge fine grid 6 near the second edge fine grid 7 is 1.4 times, the effect is the best in terms of carrier collection ability and saving the material cost of the first fine grid line 4.

[0090] In some embodiments, the first edge fine grid 6 is an equal-width section and the second edge fine grid 7 is a non-equal-width section. The first edge fine grid 6 is respectively connected to the edge main grid 2 and the second edge fine grid 7. By designing the first edge fine grid 6 as an equal-width section and the second edge fine grid 7 as a non-equal-width section, compared with designing all the first fine grid lines 4 as equal-width sections, the non-equal-width section can be used to improve the carrier collection ability and better balance the resistance of the battery.

[0091] As an embodiment of the present invention, when the first edge fine grid 6 is an equal-width section and the second edge fine grid 7 is a non-equal-width section, the ratio of the width of the second edge fine grid 7 near the middle main grid 3 to the width of the second edge fine grid 7 near the first edge fine grid 6 is greater than or equal to 1.2 times.

[0092] Among them, the ratio of the width of the second edge fine grid 7 near the middle main grid 3 to the width of the second edge fine grid 7 near the first edge fine grid 6 can be 1.2 times, 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times or greater. Specifically, it can be determined in combination with the size of the silicon wafer 1 and the actual number of the first fine grid lines 4 set. In some specific embodiments, when the ratio of the width of the second edge fine grid 7 near the middle main grid 3 to the width of the second edge fine grid 7 near the first edge fine grid 6 is 1.4 times, the effect is the best in terms of carrier collection ability and saving the material cost of the first fine grid lines 4.

[0093] As an embodiment of the present invention, the ratio of the length of the first fine grid line 4 to the length of the second fine grid line 5 is greater than or equal to 1.2 times and less than or equal to 2.0 times. By increasing the length of the first fine grid line 4 proportionally with respect to the length of the second fine grid line 5, in the case of more edge defects, the carrier collection ability of the first fine grid line 4 is increased, which is beneficial to improving the working efficiency of the battery and can better balance the carrier collection ability and the cost of the grid lines.

[0094] Among them, the ratio of the length of the first fine grid line 4 to the length of the second fine grid line 5 can be any value among 1.2 times, 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, 2.0 times. Specifically, it can be determined in combination with the size of the silicon wafer 1. In some specific embodiments, when the ratio of the length of the first fine grid line 4 to the length of the second fine grid line 5 is 1.3 times, the effect is the best in terms of carrier collection ability and saving the material cost of the first fine grid lines 4.

[0095] As an embodiment of the present invention, the height of the first fine grid line 4 is greater than or equal to 0.8 times that of the second fine grid line 5. Among them, the height of the first fine grid line 4 is the dimension in the direction perpendicular to the XY axis. For example, the height of the first fine grid line 4 can be 0.8 times, 0.9 times, 1.0 times, 1.1 times, 1.2 times or higher of the second fine grid line 5, and there is no limitation here. In the embodiment of the present invention, by setting the height ratio of the first fine grid line 4 and the second fine grid line 5 to be greater than or equal to 0.8 times, the cross-sectional area of the first fine grid line 4 is larger than that of the second fine grid line 5. Since the higher the height of the grid line, the larger the cross-sectional area of the grid line, the smaller the resistance of the grid line, and the smaller the series resistance, and the higher the fill factor and output power. Therefore, by reasonably setting the height ratio of the first fine grid line 4 and the second fine grid line 5, the resistance of the grid line can be reduced, and the carrier collection ability and the output power of the battery can be improved.

[0096] As an embodiment of the present invention, the grid line width range of the first edge fine grid 6 and the second edge fine grid 7 is 10 - 250 microns, and the specific dimensions can be determined according to the size of the silicon wafer 1 and the number of the first fine grid lines 4 provided. When the first edge fine grid 6 or the second edge fine grid 7 is a non-uniform width section or a uniform width section, the grid line width range is 10 - 250 microns. For example, it can be set to 10 microns, 20 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 90 microns, 150 microns, 250 microns, etc. In some embodiments, when the first edge fine grid 6 or the second edge fine grid 7 is a non-uniform width section, the widest part can be set to 220 microns, and when the first edge fine grid 6 or the second edge fine grid 7 is a uniform width section, the width can be set to 180 microns. The width range of the second fine grid line 5 can be set to 170 microns to optimize the performance of the battery cell.

[0097] Preferably, when the first edge fine grid 6 is a non-uniform width section and the second edge fine grid 7 is a uniform width section, the ratio of the length of the first edge fine grid 6 to the length of the second edge fine grid 7 is 0.02 - 10, that is, the length of the first edge fine grid 6 is limited to 0.02 - 10 times the length of the second edge fine grid 7. By increasing this ratio, the carrier collection ability of the first fine grid line 4 can be increased. And making the lengths of the non-uniform width and uniform width sections within a reasonable range can reduce battery leakage, improve the carrier collection ability, and avoid frequent battery leakage and poor carrier collection ability caused by unreasonable design of the lengths of both.

[0098] For example, the ratio of the length of the first edge fine grid 6 to the length of the second edge fine grid 7 can be any value among 0.02, 0.1, 0.5, 1, 2, 4, 8, 10. In some specific embodiments, when the ratio of the length of the first edge fine grid 6 to the length of the second edge fine grid 7 is 0.5, the effect is the best in terms of enhancing the carrier collection ability of the first fine grid line 4 and saving some materials.

[0099] When the second edge fine grid 7 is a uniform width section and the first edge fine grid 6 is a non-uniform width section, the ratio of the length of the second edge fine grid 7 to the length of the first edge fine grid 6 is 0.02 - 10, that is, the length of the second edge fine grid 7 is limited to 0.02 - 10 times the length of the first edge fine grid 6. By increasing this ratio, the carrier collection ability of the first fine grid line 4 can be increased. And making the lengths of the non-uniform width and uniform width sections within a reasonable range can reduce battery leakage, improve the carrier collection ability, and avoid frequent battery leakage and poor carrier collection ability caused by unreasonable design of the lengths of both.

[0100] For example, the ratio of the length of the second edge fine grid 7 to the length of the first edge fine grid 6 can be any value among 0.02, 0.1, 0.5, 1, 2, 4, 8, and 10. In some specific embodiments, when the ratio of the length of the second edge fine grid 7 to the length of the first edge fine grid 6 is 0.5, the effect is optimal in terms of enhancing the carrier collection ability of the first fine grid line 4 and saving some material settings.

[0101] As an embodiment of the present invention, when the first edge fine grid 6 is a non-uniform width section and the second edge fine grid 7 is a uniform width section, the two side lines of the first edge fine grid 6 in the extending direction are straight lines, broken lines, curves, or a combination of straight lines and curves; when the second edge fine grid 7 is a non-uniform width section and the first edge fine grid 6 is a uniform width section, the two side lines of the second edge fine grid 7 in the extending direction are straight lines, broken lines, curves, or a combination of straight lines and curves. There is no specific limitation on the shapes of the two side lines of the non-uniform width section. In practice, the shapes that are convenient for design, installation, and maintenance and satisfy that the average width is greater than the width of the uniform width section are given priority. In the embodiments of the present invention, by designing the two side lines of the non-uniform width section in the extending direction as straight lines, broken lines, curves, or a combination of straight lines and curves, and by designing the two side lines of the non-uniform width section as various lines, the area ratio of the non-uniform width section can be changed, so that the area ratio of the non-uniform width section can better meet the actual needs, balance the carrier collection ability, and reduce leakage.

[0102] As an embodiment of the present invention, when the first edge fine grid 6 is a non-uniform width section and a width-gradual section, its width from the end close to the edge main grid 2 to the end close to the second edge fine grid 7 gradually decreases to be the same as the width of the second edge fine grid 7. That is, in the X-axis direction in the figure, the width of the first edge fine grid 6 gradually decreases from one end of the edge main grid 2 to one end of the second edge fine grid 7, and the minimum width is the same as the width of the connection end with the second edge fine grid 7. At the same time, the width of the second edge fine grid 7 is greater than or equal to the width of the second fine grid line 5, that is, the overall width of the first fine grid line 4 is greater than the overall width of the second fine grid line 5.

[0103] In this way, it is beneficial to improve the carrier collection ability of the first fine grid line 4 and beneficial to improve the working efficiency of the battery; at the same time, when the width of the first fine grid line 4 at the second edge fine grid 7 is equal to the width of the second fine grid line 5, not all dimensions of the first fine grid line 4 are greater than those of the second fine grid line 5, so that while increasing the width and carrier collection ability, the material cost of some of the first fine grid line 4 is also saved; in the embodiments of the present invention, by designing the first edge fine grid 6 as a uniform width section and the second edge fine grid 7 as a non-uniform width section, compared with designing the entire first fine grid line 4 as a uniform width section, the non-uniform width section can be used to improve the carrier collection ability and better balance the resistance of the battery.

[0104] As another embodiment of the present invention, when the second edge fine grid 7 has a non-uniform width section and is a width-gradual section, the width of the second edge fine grid 7 gradually decreases from the width at the end close to the second fine grid line 5 to the width at the end close to the first edge fine grid 6 until it is the same as the width of the first edge fine grid 6. That is, in the X-axis direction in the figure, the width of the second edge fine grid 7 gradually decreases from one end of the middle main grid 3 to one end of the first edge fine grid 6, and the minimum width is the same as the width at the connection end with the first edge fine grid 6. At the same time, the width of the first edge fine grid 6 is greater than or equal to the width of the second fine grid line 5, that is, the overall width of the first fine grid line 4 is greater than the overall width of the second fine grid line 5. In this way, it is beneficial to improve the carrier collection ability of the first fine grid line 4 and improve the working efficiency of the battery; at the same time, when the width of the first fine grid line 4 at the first edge fine grid is equal to the width of the second fine grid line 5, not all dimensions of the first fine grid line 4 are greater than the second fine grid line 5, which saves part of the material cost of the first fine grid line 4 while increasing the width and carrier collection ability.

[0105] Preferably, the shape of the non-uniform width section in the top view, that is, on the plane where the XY axes are located, is one of a trapezoid and an irregular quadrilateral. When the first edge fine grid 6 has a non-uniform width section and its shape on the plane where the XY axes are located is a trapezoid, the base angle is set to 20 - 90°, and the length of its upper base is greater than or equal to 10 microns, and the length of its lower base is less than or equal to 250 microns; when the second edge fine grid 7 has a non-uniform width section and its shape on the plane where the XY axes are located is a trapezoid, the base angle is set to 20 - 90°, and the length of its upper base is greater than or equal to 10 microns, and the length of its lower base is less than or equal to 250 microns.

[0106] By reasonably setting the base angle, the length of the upper base and the length of the lower base of the trapezoid in the embodiments of the present invention, it is beneficial to improve the carrier collection ability and reduce the resistance of the battery.

[0107] As an embodiment of the present invention, at least one of the ratio of the average width of the first fine grid line 4 to the average width of the second fine grid line 5 and the ratio of the average width of the edge main grid 2 to the average width of the middle main grid 3 is greater than 1.2. For example, the ratio can be 1.2, 1.3, 1.4, 1.5, 1.6, 1.7 or higher, which is beneficial to improving the carrier collection ability of the edge grid lines.

[0108] As another embodiment of the present invention, at least one of the ratio of the maximum width of the first fine grid line 4 to the maximum width of the second fine grid line 5 and the ratio of the maximum width of the edge main grid 2 to the maximum width of the middle main grid 3 is greater than 1.2. For example, the ratio can be 1.2, 1.3, 1.4, 1.5, 1.6, 1.7 or higher, which is beneficial to improving the carrier collection ability of the edge grid lines. For example, when the first fine grid line 4 includes an equal-width section and a non-equal-width section, since the width of the non-equal-width section is gradually changing or unevenly changing, the maximum width of the non-equal-width section and the equal-width section is selected for comparison with the second fine grid line 5 at this time. The coverage area of the grid line at the maximum width is greater than that of the second fine value, and at least one of the ratio of the maximum width of the edge main grid 2 to the maximum width of the middle main grid 3 is greater than 1.2. For example, the ratio can be 1.2, 1.3, 1.4, 1.5, 1.6, 1.7 or higher, making the carrier collection ability of the first fine grid line 4 and the edge main grid 2 stronger than that of the second fine grid line 5 and the middle main grid 3.

[0109] As an embodiment of the present invention, the area ratio of the first fine grid line 4 and the second fine grid line 5 is greater than 1.2, specifically greater than 1.3 and less than 2.5. For example, the area ratio of the first fine grid line 4 and the second fine grid line 5 can be 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 to 2.5, and can be specifically designed according to the actual size ratio. In some specific embodiments, when the area ratio of the first fine grid line 4 and the second fine grid line 5 is 1.4, the effect is the best in terms of carrier collection ability and the overall layout of the fine grid lines.

[0110] As an embodiment of the present invention, a plurality of pad points 8 are provided on the edge main grid 2 and the middle main grid 3, and the plurality of pad points 8 are arranged at intervals along the length direction of the edge main grid 2 and the middle main grid 3; the width of the edge main grid 2, that is, the length in the X-axis direction is at least greater than the width of one pad point 8, and specifically can be 1.0 times, 1.1 times, 1.2 times, 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times or 2.0 times the width of the pad point 8. Preferably, the shape of the pad point 8 is a rectangle, a circle, an ellipse or a polygon with 5 sides or more. In the present invention, the pad point 8 is a rectangle, which has the advantages of being easy to design and install.

[0111] By designing the width of the edge main grid to be at least greater than the width of one pad point in the embodiment of the present invention, it is beneficial to reduce the resistance of the battery, improve the carrier collection ability, and at the same time is beneficial to improving the bonding ability between the edge grid line and the silicon wafer, and improving the reliability of the battery.

[0112] As an embodiment of the present invention, the width of the edge main grid 2 gradually decreases from the position close to the pad point 8 along the position away from the pad point 8. With such a setting, while the width of the edge main grid 2 gradually decreases, the current gradually decreases, which can ensure that the resistance of the edge main grid 2 causes relatively small power loss, and also makes the shielding rate of the edge main grid 2 lower and the usage amount of metal paste reduced; the width of the middle main grid 3 gradually decreases from the position close to the pad point 8 along the position away from the pad point 8. With such a setting, while the width of the middle main grid 3 gradually decreases, the current gradually decreases, which can ensure that the resistance of the middle main grid 3 causes relatively small power loss, and also makes the shielding rate of the middle main grid 3 lower and the usage amount of metal paste reduced. And it can ensure the stability of the connection between the edge main grid 2 and the middle main grid 3 and the pad point, and since the main grid width gradually decreases, it is beneficial to reduce costs.

[0113] As an embodiment of the present invention, at the position of the Pad point 8 close to the edge main grid 2, crossed short and thin grid lines 9 are provided for improving the current extraction at the edge.

[0114] An embodiment of the present invention provides a photovoltaic module. The photovoltaic module includes the above-mentioned back-contact solar cell, and the photovoltaic module may further include a metal frame, a back sheet, photovoltaic glass and an encapsulant film. The encapsulant film can be filled between the front and back of the back-contact solar cell and the photovoltaic glass, the back-contact solar cell, etc. As a filler, it can be a transparent colloid with good light-transmitting performance and anti-aging performance. For example, the encapsulant film can adopt an EVA encapsulant film or a POE encapsulant film, and can be specifically selected according to the actual situation, and is not limited here.

[0115] The photovoltaic glass can cover the encapsulant film on the front of the back-contact solar cell. The photovoltaic glass can be ultra-white glass, which has a high light transmittance, high transparency, and superior physical, mechanical and optical properties. For example, the light transmittance of the ultra-white glass can reach more than 9%, and it can protect the back-contact solar cell as much as possible without affecting the efficiency of the back-contact solar cell. At the same time, the encapsulant film can bond the photovoltaic glass and the back-contact solar cell together, and the presence of the encapsulant film can seal and insulate the back-contact solar cell and prevent water and moisture.

[0116] The backsheet can be attached to the adhesive film on the back of the back-contact solar cell. The backsheet can protect and support the back-contact solar cell, and has reliable insulation, water resistance and aging resistance. There are multiple choices for the backsheet, which can usually be tempered glass, plexiglass, aluminum alloy TPT composite film, etc., and can be specifically set according to specific circumstances, which are not limited here. The whole composed of the backsheet, the back-contact solar cell, the adhesive film and the photovoltaic glass can be arranged on the metal frame. The metal frame is the main external support structure of the whole photovoltaic module, and can stably support and install the photovoltaic module. For example, the photovoltaic module can be installed at the required installation position through the metal frame.

[0117] An embodiment of the present invention provides a photovoltaic system, including the above-mentioned photovoltaic module.

[0118] In this embodiment, the photovoltaic system can be applied in photovoltaic power stations, such as ground power stations, rooftop power stations, water surface power stations, etc., and can also be applied to devices or apparatuses that use solar energy for power generation, such as user solar power supplies, solar street lights, solar cars, solar buildings, and so on. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is to say, the photovoltaic system can be applied in all fields that require solar power generation. Taking the photovoltaic power generation system network as an example, the photovoltaic system can include a photovoltaic array, a combiner box and an inverter. The photovoltaic array can be an array combination of multiple photovoltaic modules. For example, multiple photovoltaic modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, and the combiner box can collect the current generated by the photovoltaic array. After the collected current flows through the inverter and is converted into alternating current required by the commercial power grid, it is connected to the commercial power grid to achieve solar power supply.

[0119] In the above embodiments, the descriptions of each embodiment have their own emphases. For the parts not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0120] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0121] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0122] In the present invention, unless otherwise clearly specified and defined, terms such as "mounted", "connected", "coupled", "fixed", etc. shall be construed in a broad sense. For example, it may be a connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0123] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely means that the horizontal height of the first feature is lower than that of the second feature.

[0124] In the description of this specification, the description with reference to terms such as "an embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0125] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, provided that these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

[0126] As described above, the specific implementation manners of the present invention are provided, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A back contact solar cell, characterized in that: include: A silicon wafer, wherein an edge main grid and an intermediate main grid adjacent to the edge main grid are arranged on the back side of the silicon wafer; A first fine grid line disposed on the edge main grid; A second fine grid line disposed on the middle main grid; The first fine grid line includes a first edge fine grid and a second edge fine grid, one of the first edge fine grid and the second edge fine grid is an unequal width segment, and the other is an equal width segment, the width of the equal width segment is greater than or equal to the second fine grid line, and the average width of the unequal width segment is greater than the width of the equal width segment.

2. The back contact solar cell according to claim 1, characterized in that: The first edge fine grid is a segment of non-uniform width, the second edge fine grid is a segment of uniform width, and the first edge fine grid is connected to the edge main grid and the second edge fine grid respectively.

3. The back contact solar cell according to claim 2, characterized in that: The overall area of ​​the first fine gate lines is greater than 0.108 cm2.

4. The back contact solar cell according to claim 2, characterized in that: The first edge fine grid is a width gradient section, and the width gradually decreases from the width close to one end of the edge main grid to the width of one end of the second edge fine grid until it is consistent with the width of the second edge fine grid.

5. The back contact solar cell according to claim 1, characterized in that: The first edge fine grid is a segment of equal width, the second edge fine grid is a segment of unequal width, and the first edge fine grid is connected to the edge main grid and the second edge fine grid respectively.

6. The back contact solar cell according to claim 5, characterized in that: The overall area of ​​the first fine gate lines is greater than 0.108 cm2.

7. The back contact solar cell according to claim 5, characterized in that The second edge fine grid is a width gradient section, and the second edge fine grid gradually decreases from the width close to one end of the second fine grid line to the width close to one end of the first edge fine grid until it is consistent with the width of the first edge fine grid.

8. The back contact solar cell according to claim 1, characterized in that: The shape of the first edge grating or the second edge grating in a top view is one of a trapezoid and an irregular trapezoid.

9. The back contact solar cell according to claim 8, characterized in that: When the top view of the first edge grating is in the shape of a trapezoid, the bottom angle of the trapezoid is set to 20 degrees to 90 degrees; or When the top view of the second edge fine grid is in the shape of a trapezoid, the bottom angle of the trapezoid is set to be 20 degrees to 90 degrees.

10. The back contact solar cell according to claim 8, characterized in that: When the shape of the top view of the first edge fine grid is a trapezoid, the length of the upper base of the trapezoid is greater than or equal to 10 micrometers, and the length of the lower base of the trapezoid is less than or equal to 250 micrometers; or When the shape of the top view of the second edge fine grid is a trapezoid, the length of the upper base of the trapezoid is greater than or equal to 10 micrometers, and the length of the lower base of the trapezoid is less than or equal to 250 micrometers.

11. The back contact solar cell according to claim 1, characterized in that: When the first edge fine grid is a segment of non-uniform width, two side lines in the extension direction thereof are straight lines, broken lines, curves, or a combination of straight lines and curves; or When the second edge fine grid is a segment of non-uniform width, two side lines in the extension direction thereof are straight lines, broken lines, curves or a combination of straight lines and curves.

12. The back contact solar cell according to claim 1, characterized in that: When the first edge thin grid is a segment of non-uniform width and the second edge thin grid is a segment of uniform width, the length ratio of the first edge thin grid to the second edge thin grid is 0.02-10; or When the first edge thin grid is a segment of equal width and the second edge thin grid is a segment of unequal width, a length ratio of the second edge thin grid to the first edge thin grid is 0.02-10.

13. The back contact solar cell according to claim 1, characterized in that: When the first edge fine grid or the second edge fine grid is a segment of non-uniform width, the gate line width ranges from 10 to 250 micrometers.

14. The back contact solar cell according to claim 1, characterized in that: When the first edge fine grid or the second edge fine grid is a segment of equal width, the gate line width ranges from 10 to 250 micrometers.

15. The back contact solar cell according to claim 1, characterized in that: When the first edge fine grid is a non-uniform width segment and the second edge fine grid is an equal width segment, the ratio of the width of the first edge fine grid close to the edge main grid to the width of the first edge fine grid close to the second edge fine grid is greater than or equal to 1.2 times; or When the first edge thin gate is a segment of equal width and the second edge thin gate is a segment of unequal width, the ratio of the width of the second edge thin gate close to the middle main gate to the width of the second edge thin gate close to the first edge thin gate is greater than or equal to 1.2 times.

16. The back contact solar cell according to claim 1, characterized in that: A height ratio of the first thin gate line to the second thin gate line is greater than or equal to 0.8 times.

17. The back contact solar cell according to claim 1, characterized in that: The length ratio of the first thin gate line to the second thin gate line is 1.2-2.

0.

18. The back contact solar cell according to claim 1, characterized in that: A plurality of pad points are arranged on the edge main grid and the middle main grid, and the plurality of pad points are arranged at intervals along the length direction of the edge main grid and the middle main grid.

19. The back contact solar cell according to claim 18, characterized in that: The widths of the edge main grid and the middle main grid gradually decrease from a position close to the pad point to a position away from the pad point.

20. The back contact solar cell according to claim 1, characterized in that: The width of the edge main grid ranges from 25 to 1200 microns.

21. The back contact solar cell according to claim 1, characterized in that: The width of the intermediate main grid is in the range of 10-1200 microns.

22. The back contact solar cell according to claim 18, characterized in that The shape of the pad point is at least one of a rectangle, a polygon, and a circle.

23. The back contact solar cell according to claim 18, characterized in that The width of the edge main gate is at least greater than the width of one of the pad points.

24. The back contact solar cell according to claim 18, characterized in that A cross-shaped short fine grid line is arranged at a position close to the pad point of the edge main grid.

25. The back contact solar cell according to claim 1, characterized in that: At least one of a ratio of an average width of the first thin gate lines to an average width of the second thin gate lines and a ratio of an average width of the edge main gate to an average width of the middle main gate is greater than 1.

2.

26. The back contact solar cell according to claim 1, characterized in that: At least one of a ratio of a maximum width of the first thin gate line to a maximum width of the second thin gate line and a ratio of a maximum width of the edge main gate to a maximum width of the middle main gate is greater than 1.

2.

27. The back contact solar cell according to claim 1, characterized in that An area ratio of the first thin gate line to the second thin gate line is greater than 1.

2.

28. The back contact solar cell according to claim 27, characterized in that The area ratio of the first thin gate line to the second thin gate line is in a range of 1.3-2.

5.

29. The back contact solar cell according to claim 1, characterized in that The overall area of ​​the second thin grid line is in the range of 0.09-15 cm 2 .

30. A photovoltaic module, characterized in that: Comprising the solar cell according to any one of claims 1 to 29.

31. A photovoltaic system, characterized in that: Comprising the photovoltaic module as claimed in claim 30.

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