Solar cell

Abstract

The invention relates to the technical field of solar cells, and provides a solar cell, which comprises a silicon wafer and a plurality of current collection units, the current collection units are distributed on the silicon wafer in M rows and N columns and are electrically connected with the silicon wafer, M is greater than 2, N is greater than 2, and two adjacent current collection units are electrically connected. Each current collection unit comprises a plurality of groups of current lead-out grid lines, each group of current lead-out grid lines are connected end to end in sequence to form a Kairou pentagon structure, and the Kairou pentagon structures are spliced with one another. The current collection unit further comprises current collection electrodes, the current collection electrodes are electrically connected with the current lead-out grid lines, and one current collection electrode is designed between at least one group of two connected current lead-out grid lines. The solar cell provided by the invention can effectively reduce the shielding of the current lead-out grid lines to sunlight, and increases the effective light absorption surface of the surface of the solar cell, thereby effectively improving the photoelectric conversion efficiency of the solar cell.

Description

Technical Field

[0001] This application relates to the field of solar energy technology, and particularly to a solar cell. Background Art

[0002] A solar cell, also known as a photovoltaic cell, is a device that directly converts sunlight into electrical energy. The working principle of a solar cell mainly relies on the photovoltaic effect. When photons in sunlight irradiate a solar cell, semiconductor silicon excites photoelectrons, thereby generating an electric current.

[0003] Generally, metal grid lines are provided on a silicon wafer. The metal grid lines can be used to conduct current to conduct the current to a current collection electrode, thereby achieving current collection. Currently, the metal grid lines are usually distributed on the silicon wafer in a straight line or matrix grid form. However, in the above distribution methods, as the number of metal grid lines increases, the metal grid lines will block the silicon wafer, reducing the effective irradiation area of sunlight on the silicon wafer, greatly reducing the effective light-absorbing surface on the surface of the solar cell, and thus reducing the photoelectric conversion efficiency of the solar cell. Summary of the Invention

[0004] This application provides a solar cell that can effectively reduce the blockage of sunlight by current extraction grid lines, increase the effective light-absorbing surface on the surface of the solar cell, and thus effectively improve the photoelectric conversion efficiency of the solar cell.

[0005] This application provides a solar cell, including:

[0006] A silicon wafer;

[0007] A plurality of current collection units, the current collection units are distributed on the silicon wafer in an M-row and N-column manner and are electrically connected to the silicon wafer, where M is greater than 2, N is greater than 2, and two adjacent current collection units are electrically connected;

[0008] Each current collection unit includes:

[0009] Multiple groups of current extraction grid lines, each group of current extraction grid lines are connected end to end in sequence to enclose a Cairo pentagon structure, and the Cairo pentagon structures are spliced with each other;

[0010] A current collection electrode, the current collection electrode is electrically connected to the current extraction grid lines, and there is one current collection electrode between at least one group of two adjacent current extraction grid lines.

[0011] By surrounding and forming a Cairo pentagon structure with current extraction grid lines, the current extraction grid lines can extend along different directions, creating gaps between the current extraction grid lines to facilitate sunlight to shine on the silicon wafer through the gaps. In this way, without reducing the current collection amount, the shading of sunlight by the current extraction grid lines can be effectively reduced, increasing the effective light-absorbing area on the surface of the solar cell, thereby effectively improving the photoelectric conversion efficiency of the solar cell.

[0012] In a possible implementation manner, two adjacent Cairo pentagon structures share the same current extraction grid line.

[0013] In a possible implementation manner, two adjacent current collection units share the same current extraction grid line.

[0014] In a possible implementation manner, two adjacent current collection units are electrically connected through the current collection electrode, and share the current collection electrode at this part.

[0015] In a possible implementation manner, each current collection unit includes four Cairo pentagon structures, and two adjacent Cairo pentagon structures share the same current extraction grid line.

[0016] In a possible implementation manner, the Cairo pentagon includes four long sides and one short side connected end to end in sequence, and the ratio of the length of the long side to the short side is

[0017] In a possible implementation manner, the four long sides are respectively the first long side, the second long side, the third long side, and the fourth long side. The first long side, the second long side, the third long side, and the fourth long side are connected end to end in sequence. The two ends of the short side are respectively connected to the first long side and the fourth long side to form a closed Cairo pentagon structure;

[0018] The angle between the first long side and the second long side is the first angle, the angle between the second long side and the third long side is the second angle, the angle between the third long side and the fourth long side is the third angle, the angle between the fourth long side and the short side is the fourth angle, and the angle between the short side and the first long side is the fifth angle;

[0019] The first angle is equal to the third angle, and the second angle, the fourth angle, and the fifth angle are equal.

[0020] In a possible implementation manner, the angles of the first angle and the third angle are 90°, and the angles of the second angle, the fourth angle, and the fifth angle are 120°.

[0021] In a possible implementation, the current collection electrode is circular, and the diameter of the current collection electrode is 0.060 mm - 0.160 mm.

[0022] In a possible implementation, the width of the current extraction grid line is 0.015 mm - 0.040 mm, and the height is 0.015 mm - 0.040 mm.

[0023] In a possible implementation, let the length of the silicon wafer be A, the width be B, the long side of the Cairo pentagon structure be x, and the short side be The M satisfies the following relational expression:

[0024]

[0025] The N satisfies the following relational expression:

[0026] BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0028] Figure 1 It is a schematic structural diagram of a solar cell provided by an embodiment of the present application;

[0029] Figure 2 It is a schematic structural diagram of a current collection unit provided by an embodiment of the present application;

[0030] Figure 3 It is a schematic diagram of a Cairo pentagon structure provided by an embodiment of the present application;

[0031] Figure 4 It is the simulation result of the solar cell provided by Embodiment 1 of the present application;

[0032] Figure 5 It is the simulation result of the solar cell provided by Embodiment 2 of the present application;

[0033] Figure 6 It is the simulation result of the solar cell provided by Embodiment 3 of the present application.

[0034] REFERENCE NUMERALS:

[0035] 10 - solar cell;

[0036] 100 - Silicon wafer;

[0037] 200 - Current collection unit;

[0038] 210 - Current extraction grid line; 211 - Cairo pentagon structure;

[0039] 211a - First long side; 211b - Second long side; 211c - Third long side;

[0040] 211d - Fourth long side; 211e - Short side;

[0041] 220 - Current collection electrode. Detailed implementation manner

[0042] 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 some, but not all, of the embodiments of the present invention. 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.

[0043] As described in the background art above, generally, metal grid lines are provided on the silicon wafer in a solar cell. The metal grid lines can be used to conduct current to conduct the current to the current collection electrode, thereby achieving current collection. Currently, the metal grid lines are usually distributed on the silicon wafer in a straight line or matrix grid form. Specifically, usually, multiple straight metal grid lines are distributed in parallel. At the end of the metal grid lines, a main return bar is provided, and the metal grid lines are electrically connected to the main return bar. The main bus bar is used to collect and conduct current to collect the current.

[0044] However, in the above distribution method, the metal grid lines are distributed in the same direction, and their distribution form is single, and the overall structural strength of the metal grid lines is weak. Under the action of external mechanical force, stress concentration is likely to occur, resulting in the grid lines breaking or failing, reducing the service life of the solar cell.

[0045] Moreover, as the number of metal grid lines increases, the metal grid lines will block the silicon wafer, reducing the effective irradiation area of sunlight on the silicon wafer, greatly reducing the effective light absorption surface on the surface of the solar cell, and thus reducing the photoelectric conversion efficiency of the solar cell.

[0046] In addition, in the structure of the straight-line distributed metal grid lines, the current transmission paths on the silicon wafer to the metal grid lines are uneven, making some current transmission paths longer, increasing the series resistance of the solar cell, and thus increasing the power loss of the cell.

[0047] To solve the above problems, an embodiment of the present application provides a solar cell. By forming a Cairo pentagon structure with the current extraction grid lines, the current extraction grid lines extend along different directions, and gaps can be formed between the current extraction grid lines, facilitating sunlight to irradiate the silicon wafer through the gaps. In this way, without reducing the current collection amount, the shielding of sunlight by the current extraction grid lines can be effectively reduced, the effective light absorption area on the surface of the solar cell is increased, and thus the photoelectric conversion efficiency of the solar cell is effectively improved.

[0048] Moreover, the current extraction grid lines extend along different directions, thus having relatively high structural strength. This structure enables the current extraction grid lines to resist external mechanical forces, avoid stress concentration, effectively reduce or avoid risks such as the current extraction grid lines breaking or failing, thereby prolonging the service life of the current grid lines, and further improving the overall service life of the solar cell.

[0049] In addition, the distribution form of the current extraction grid lines in the Cairo pentagon structure can effectively improve the uniformity of the distribution of the current extraction grid lines on the silicon wafer, reduce the distance for the current on the silicon wafer to be transmitted between the current extraction grid lines, effectively reduce the series resistance of the solar cell, and further reduce the power loss of the solar cell.

[0050] The following will describe in detail a snap device provided by an embodiment of the present application with reference to the accompanying drawings.

[0051] Figure 1 It is a schematic structural diagram of a solar cell provided by an embodiment of the present application. Figure 2 It is a schematic structural diagram of a current collection unit provided by an embodiment of the present application.

[0052] An embodiment of the present application provides a solar cell 10. As shown in Figure 1 , the solar cell 10 may include a silicon wafer 100 and a plurality of current collection units 200. The plurality of current collection units 200 are distributed on the silicon wafer 100 in an M-row and N-column manner and are electrically connected to the silicon wafer 100. Among them, M is greater than 2, and N is greater than 2. And, two adjacent current collection units 200 are electrically connected.

[0053] For example, the current collection unit 200 can be plated on the silicon wafer 100 by electroplating or other means to achieve electrical connection with the silicon wafer 100. And two adjacent current collection units 200 can be in contact with each other so that two adjacent current collection units 200 can be electrically connected to achieve current transmission.

[0054] Combined with Figure 2As shown in the figure, each current collection unit 200 includes multiple groups of current extraction grid lines 210. Each group of current extraction grid lines 210 can be connected end to end in sequence to enclose a Cairo pentagon structure 211, and multiple Cairo pentagon structures 211 are spliced together. For example, the current extraction grid lines 210 can be thin metal grid lines. For example, the material of the current extraction grid lines 210 can be copper. The photoelectrons on the silicon wafer 100 can be transmitted to the current extraction grid lines 210 to be extracted through the current extraction grid lines 210.

[0055] The current collection unit 200 may further include a current collection electrode 220, and the current collection electrode 220 is electrically connected to the current extraction grid lines 210. Among them, a current collection electrode 220 is provided between at least one group of two connected current extraction grid lines 210 to realize the electrical connection of the two current extraction grid lines 210 through the current collection electrode 220. For example, as shown in the figure, a current collection electrode 220 is provided at the intersection position of two current extraction grid lines 210 to realize the electrical connection of the current collection electrode 220 and the two current extraction grid lines 210.

[0056] During the operation of the solar cell, sunlight irradiates on the silicon wafer 100, and photo-generated carriers (i.e., photo-generated electron-hole pairs) can be excited. The electrons among them can be transmitted to the current extraction grid lines 210 and transmitted along the current extraction grid lines 210 to the current collection electrode 220 to realize the collection of current.

[0057] Among them, the current extraction grid lines 210 enclose a Cairo pentagon structure 211. The Cairo pentagon structure 211 is a special pentagon, different from the traditional equilateral pentagon, and it has good tiling performance and can be arranged repeatedly on a plane without leaving gaps or overlaps. Such a structure can make more current extraction grid lines 210 distributed under the same area, thereby improving the current collection efficiency. At the same time, the current extraction grid lines 210 can extend along different directions, which can effectively improve the uniformity of the distribution of the current extraction grid lines 210 and enhance the structural strength of the current extraction grid lines 210.

[0058] In the embodiment of the present application, by making the current extraction grid lines 210 enclose a Cairo pentagon structure 211 and the current extraction grid lines 210 extend along different directions, gaps can be formed between the current extraction grid lines 210, facilitating sunlight to irradiate on the silicon wafer 100 through the gaps. This enables the current extraction grid lines 210 to effectively reduce the occlusion of the circuit extraction grid lines and sunlight without reducing the current collection amount, and can effectively increase the effective light absorption area on the surface of the solar cell 10, thereby effectively improving the photoelectric conversion efficiency of the solar cell 10.

[0059] Moreover, the current extraction grid lines 210 extend along different directions, which can make the overall structure strength of the current extraction grid lines 210 relatively high. The current extraction grid lines 210 can resist external mechanical forces, reduce stress concentration under external mechanical forces, and effectively reduce or avoid the occurrence of risk situations such as fracture or failure of the current extraction grid lines 210, thereby effectively improving the service life of the current grid lines and prolonging the overall service life of the solar cell.

[0060] In addition, the distribution form of the current extraction grid lines 210 of the Cairo pentagon structure 211 can effectively improve the uniformity of the distribution of the current extraction grid lines 210 on the silicon wafer 100, reduce the transmission distance between the current transmissions on the silicon wafer 100 to the current extraction grid lines 210, effectively reduce the series resistance of the solar cell 10, and thus effectively reduce the power loss of the solar cell 10.

[0061] Continue to refer to Figure 1 and Figure 2 As shown, two adjacent Cairo pentagon structures 211 can share a current extraction grid line 210. That is to say, when the Cairo pentagon structures 211 are spliced, two adjacent Cairo pentagon structures 211 can share the same current extraction grid line 210 at the splicing position. In this way, without reducing the current conduction effect, the width of the current extraction grid line 210 at this part can be effectively reduced, and it can reduce or avoid the width of the current extraction grid line 210 being too wide and affecting the irradiation area of sunlight on the silicon wafer 100, which helps to reduce the shading area at this part, further improve the effective light absorption surface on the surface of the solar cell 10, and thus effectively improve the photoelectric conversion efficiency of the solar cell 10.

[0062] Continue to refer to Figure 1 As shown, two adjacent current collection units 200 can share the same current extraction grid line 210. For example, refer to Figure 1 As shown, in the length direction of the silicon wafer 100 (i.e., Figure 1 the x direction in

[0063] ), two adjacent current collection units 200 can share the same current extraction grid line 210 at the contact part.

[0064] Continue to refer to Figure 1 As shown, two adjacent current collection units 200 can also be electrically connected through a current collection electrode 220, and the current collection electrode 220 is shared at this part. For example, refer to Figure 1 As shown, in the width direction of the silicon wafer 100 (i.e., Figure 1 the y direction in

[0065] ), two adjacent current collection units 200 can be electrically connected through a current collection electrode 220. By making two adjacent current collection units 200 share the current collection electrode 220 at the electrical connection part, on the premise of not affecting the current collection effect, the number of current collection electrodes 220 at this part can be reduced, thereby effectively reducing the occlusion of light by the current collection electrode 220, helping to reduce the light-shielding area at this part, increasing the effective light-absorbing area on the surface of the solar cell 10, and further improving the photoelectric conversion efficiency of the solar cell 10.

[0066] Refer to Figure 2 As shown, each current collection unit 200 can include 4 Cairo pentagon structures 211, and two adjacent Cairo pentagon structures 211 can share the same current lead-out grid line 210. For example, refer to Figure 2 As shown, the four Cairo pentagon structures 211 can be spliced in the Figure 2 way in Figure 2 shown, that is, two of them can be spliced vertically first, and then the remaining two are spliced on the left and right sides to form a complete current collection unit 200. The above up, down, left, and right are defined according to the orientation shown in

[0067] The above four Cairo pentagon structures 211 can be spliced into a complete graphic structure, which has no omission or vacancy, nor overlap, and each Cairo pentagon structure 211 fits perfectly. This design can effectively improve the uniformity and regularity of the distribution of the current lead-out grid line 210, can effectively improve the rationality of the distribution of the current lead-out grid line 210 on the silicon wafer 100, thereby effectively improving the current lead-out efficiency of the current lead-out grid line 210, and also helps to improve the structural stability of the overall structure of the current lead-out grid line 210, enhance the structural strength of the current lead-out grid line 210, and thus effectively improve the anti-fracture performance of the overall structure of the current lead-out grid line 210.

[0068] Figure 3 It is a schematic diagram of a Cairo pentagon structure provided by an embodiment of the present application.

[0069] Refer to Figure 3 As shown, the Cairo pentagon structure 211 can include four long sides connected end to end in sequence (i.e., Figure 3211a, 211b, 211c, 211d in) and a short side 211e (i.e., Figure 3 211e in), and the ratio of the length of the long side to the short side 211e is That is, the lengths of the four long sides are equal, and the ratio of the lengths of the four long sides to the length of the short side 211e is Among them, the four long sides can be connected in sequence, and the two ends of the short side 211e can be respectively connected to the first long side and the fourth long side to form a closed Cairo pentagon structure 211.

[0070] By making the ratio between the long side of the Cairo pentagon structure 211 and the short side 211e be It is possible to make multiple Cairo pentagon structures 211 have no extra gaps, clearances, and overlaps when splicing, so that multiple Cairo pentagon structures 211 can be spliced into a complete graphic structure. This can effectively improve the uniformity and rationality of the distribution of the current extraction grid line 210 on the silicon wafer 100, contribute to improving the current extraction efficiency of the current extraction grid line 210, and also help to improve the structural stability of the overall structure of the current extraction grid line 210, enhance the structural strength of the current extraction grid line 210, and thus effectively enhance the anti-fracture performance of the overall structure of the current extraction grid line 210.

[0071] Continue to refer to Figure 3 As shown, among them, the four long sides can be respectively the first long side 211a, the second long side 211b, the third long side 211c, and the fourth long side 211d. The first long side 211a, the second long side 211b, the third long side 211c, and the fourth long side 211d can be connected end to end in sequence, and the two ends of the short side 211e can be respectively connected to the first long side 211a and the fourth long side 211d to form a closed Cairo pentagon structure 211.

[0072] It should be noted that the Cairo pentagon structure 211 is formed by enclosing the current extraction grid line 210. Therefore, the long side and the short side 211e of the Cairo pentagon structure 211 are both the current extraction grid line 210. The current extraction grid line 210 is the long side and the short side 211e of the Cairo pentagon structure 211. For example, the current extraction grid line 210 with a longer length constitutes the long side of the Cairo pentagon structure 211, and the current extraction grid line 210 with a shorter length can be the short side 211e of the Cairo pentagon structure 211.

[0073] The included angle between the first long side 211a and the second long side 211b can be the first included angle a, the included angle between the second long side 211b and the third long side 211c can be the second included angle b, the included angle between the third long side 211c and the fourth long side 211d can be the third included angle c, the included angle between the fourth long side 211d and the short side 211e can be the fourth included angle d, and the included angle between the short side 211e and the first long side 211a can be the fifth included angle e.

[0074] Among them, the first included angle a can be equal to the third included angle c, and the second included angle b can be equal to the fourth included angle d and the fifth included angle e. This can make the Cairo pentagon structure 211 formed by the current extraction grid lines 210 a symmetric structure. During the splicing process of the Cairo pentagon structures 211, the splicing between the Cairo pentagon structures 211 can be more fitting, effectively reducing or avoiding defects such as gaps, clearances, overlaps, and protrusions in the spliced graphic structure. It can effectively improve the uniformity of the distribution of the current extraction grid lines 210 on the silicon wafer 100.

[0075] See Figure 3 As shown, the angles of the first included angle a and the third included angle c can be 90°, and the angles of the second included angle b, the fourth included angle d, and the fifth included angle e can be 120°. In this way, a standard Cairo pentagon structure 211 can be formed, making the Cairo pentagon structure 211 a symmetric structure. As shown in the figure, during the splicing process, as Figure 3 shown, the upper and lower Cairo pentagon structures 211 can share a short side 211e for splicing. The other two Cairo pentagon structures 211 can be located on the left and right sides respectively, and are spliced with the long sides of the upper and lower Cairo pentagon structures 211 through the long sides on both sides of the second included angle b to form a complete current collection unit 200.

[0076] This can effectively improve the integrity of the splicing of the Cairo pentagon structure 211, effectively reducing or avoiding defects such as gaps, clearances, overlaps, and protrusions in the spliced graphic structure. It can effectively improve the uniformity of the distribution of the current extraction grid lines 210 on the silicon wafer 100. Moreover, it can effectively improve the overall structural stability of the current collection unit 200, thereby effectively reducing or avoiding the breakage of the current extraction grid lines 210 in the current collection unit 200 under external forces, and effectively improving the service life of the solar cell 10.

[0077] See Figure 2As shown, the current collection electrode 220 can be circular. The circular current collection electrode 220 can be produced by deformation processing. The diameter of the current collection electrode 220 can be 0.060 mm - 0.160 mm. If the diameter of the current collection electrode 220 is too small, it will affect the current collection efficiency of the current collection electrode 220. If the diameter is too large, it will increase the blockage of sunlight by the current collection electrode 220. By making the diameter of the current collection electrode 220 be 0.060 mm - 0.160 mm, it is possible to effectively reduce or avoid the influence on the current collection efficiency due to the too small size of the current collection electrode 220, and it can effectively improve the current collection efficiency of the current collection electrode 220.

[0078] And on the premise of improving the current collection efficiency, it is possible to reduce or avoid the increase in the blockage of light due to the too large size of the current collection electrode 220, and it can effectively reduce the blockage of sunlight by the current collection electrode 220. This helps to reduce the light-blocking area of this part and increase the effective light-absorbing area on the surface of the solar cell 10, thereby effectively improving the photoelectric conversion efficiency of the solar cell 10.

[0079] Continue to refer to Figure 2 As shown, the width of the current lead-out grid line 210 can be 0.015 mm - 0.040 mm, and the height can be 0.015 mm - 0.040 mm. If the width of the current lead-out grid line 210 is too small, it will increase the resistance of the current lead-out grid line 210. If the width is too wide, it will increase the blockage of light by the current lead-out grid line 210 and affect the illumination of the silicon wafer 100 by sunlight.

[0080] By making the width of the current lead-out grid line 210 be 0.015 mm - 0.040 mm, it is possible to effectively reduce or avoid the increase in its own resistance due to the too small size of the current lead-out grid line 210, and it can effectively reduce the resistance of the current lead-out grid line 210. Moreover, it can also reduce or avoid the increase in the blockage of light due to the too large size of the current lead-out grid line 210, and it can effectively reduce the blockage of sunlight by the current lead-out grid line 210. This helps to reduce the light-blocking area of this part and increase the effective light-absorbing area on the surface of the solar cell 10, thereby effectively improving the photoelectric conversion efficiency of the solar cell 10.

[0081] By making the height of the current lead-out grid line 210 be 0.015 mm - 0.040 mm, on the premise of not increasing the blockage of light by the current lead-out grid line 210, it is possible to effectively improve the structural strength of the current lead-out grid line 210.

[0082] Refer to Figure 1 As shown, where the length of the silicon wafer 100 is A, the width is B, the long side of the Cairo pentagon structure 211 is x, and the short side 211e is M can satisfy the following relational expression:

[0083]

[0084] N satisfies the following relational expression:

[0085]

[0086] Through the above formula, the number of current collection units 200 in the silicon wafer 100 with different lengths and widths can be calculated, and then relevant parameters such as the overall shading area of the current collection units 200 can be deduced.

[0087] Among them, according to the above formula, it can be obtained that on the premise that the length and width of the silicon wafer 100 are determined, the number of current collection units 200 distributed on the silicon wafer 100 is related to the length of the current extraction grid line 210 (that is, the length x of the long side of the Cairo pentagon structure 211). That is, the longer the length of the current extraction grid line 210, the smaller the number of current collection units 200 distributed on the silicon wafer 100, the corresponding smaller shading area of the current collection units 200, the larger the effective light absorption area of the solar cell 10, and thus the higher the photoelectric conversion efficiency. However, increasing the length of the current extraction grid line 210 will cause the current transmission path to become longer, reduce the current collection efficiency, increase the series resistance, and further reduce the fill factor of the solar cell 10, ultimately reducing the photoelectric conversion efficiency of the solar cell 10.

[0088] On the contrary, the shorter the length of the current extraction grid line 210, the more the number of current collection units 200 distributed on the silicon wafer 100. Correspondingly, the shorter the length of the current extraction grid line 210, the shorter the current transmission path will be, reducing the current collection efficiency, reducing the series resistance and thus increasing the fill factor of the solar cell 10, improving the photoelectric conversion efficiency of the solar cell 10. However, the shading area of the current collection units 200 will also increase, and the effective light absorption area of the solar cell 10 will be reduced, thus reducing the photoelectric conversion efficiency.

[0089] Therefore, the length of the current extraction grid line 210 (that is, the length x of the long side of the Cairo pentagon structure 211) is not the longer the better, nor the shorter the better, but within a suitable value range to achieve a relative balance between the shading area of the current extraction grid line 210 and the current collection efficiency, and effectively improve the current collection efficiency on the premise that the shading area of the current extraction grid line 210 in the solar cell 10 is small.

[0090] For example, in the embodiment of the present application, the length of the silicon wafer 100 can be 150 mm - 220 mm, and the width can be 95 mm - 220 mm. For example, the length of the silicon wafer 100 can be 210 mm, 182 mm, 156 mm, and the width of the silicon wafer 100 can be 105 mm, 182 mm, 156 mm, 158 mm, etc.

[0091] The long side length of the Cairo pentagon structure 211 can be 1.5 mm - 4 mm. For example, the long side length of the Cairo pentagon structure 211 can be 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, etc. The above values can make the current extraction grid line 210 have a lower light-shielding area, and can also make the solar cell 10 have a better current collection effect. A better balance is achieved between the shielding area of the current extraction grid line 210 and the current collection efficiency of the solar cell 10.

[0092] The following conducts an experimental analysis on the solar cell 10 provided in the embodiment of the present application in conjunction with the attached drawings.

[0093] Figure 4 It is the simulation result of the solar cell provided in the first embodiment of the present application.

[0094] First Embodiment

[0095] Referring to Table 1, in the first embodiment, a silicon wafer 100 with a length of 210 mm and a width of 105 mm is selected. The current collection unit 200 is drawn on the silicon wafer 100 by electroplating. Among them, the length of the long side x of the Cairo pentagon structure 211 formed by the current extraction grid line 210 in the current collection unit 200 is 2.2 mm, the width is 0.025 mm, the diameter of the current collection electrode 220 is 0.1 mm, the number of the current collection units 200 distributed in the length direction of the silicon wafer 100 (i.e., the value of M) is 27, and the number of the current collection units 200 distributed in the short side 211e direction of the silicon wafer 100 (i.e., the value of N) is 17.

[0096] Table 1

[0097]

[0098] Referring to Figure 4 As shown, based on the structure of the current collection unit 200 of the first embodiment being used on the front and back of the HJT solar cell 10, after simulation by the solar simulation software, as Figure 4 shown, the results are: the conversion efficiency Eta of the solar cell = 25.76%, the open-circuit voltage Uoc = 746 mV, the short-circuit current density Jsc = 42.92 mA / cm 2 , and the fill factor FF = 80.43%.

[0099] Figure 5 It is the simulation result of the solar cell provided in the second embodiment of the present application.

[0100] Second Embodiment

[0101] As shown in Table 2, in Example 3, a silicon wafer 100 with a length of 210 mm and a width of 105 mm is selected. The current collection unit 200 is drawn on the silicon wafer 100 by electroplating. Among them, the length of the long side x of the Cairo pentagon structure 211 formed by the current extraction grid line 210 in the current collection unit 200 is 2.5 mm, the width is 0.035 mm, the diameter of the current collection electrode 220 is 0.14 mm, the number of current collection units 200 distributed in the length direction of the silicon wafer 100 (i.e., the value of M) is 24, and the number of current collection units 200 distributed in the short side 211e direction of the silicon wafer 100 (i.e., the value of N) is 15.

[0102] Table 2

[0103]

[0104] Based on the structure of the current collection unit 200 used on the front and back of the HJT solar cell 10 in this example, after simulation by solar cell simulation software, see Figure 5 shown, the test results are as follows: the conversion efficiency Eta of the solar cell is 25.33%, the open-circuit voltage Uoc is 741 mV, and the short-circuit current density Jsc is 42.75 mA / cm 2 , and the fill factor FF is 79.95%.

[0105] Figure 6 These are the simulation results of the solar cell provided in Example 3 of this application.

[0106] Example 3

[0107] As shown in Table 3, in Example 3, a silicon wafer 100 with a length of 210 mm and a width of 105 mm is selected. The current collection unit 200 is drawn on the silicon wafer 100 by electroplating. Among them, the length of the long side x of the Cairo pentagon structure 211 formed by the current extraction grid line 210 in the current collection unit 200 is 3 mm, the width is 0.045 mm, the diameter of the current collection electrode 220 is 0.18 mm, the number of current collection units 200 distributed in the length direction of the silicon wafer 100 (i.e., the value of M) is 20, and the number of current collection units 200 distributed in the short side 211e direction of the silicon wafer 100 (i.e., the value of N) is 12.

[0108] Table 1

[0109]

[0110] Based on the structure of the current collection unit 200 of this Example 3 used on the front and back of the HJT solar cell 10, after simulation by solar simulation software, see Figure 6As shown, the results are as follows: the conversion efficiency Eta of the solar cell is 23.68%, the open-circuit voltage Uoc is 738 mV, and the short-circuit current density Jsc is 41.88 mA / cm 2 , and the fill factor FF is 76.65%.

[0111] Comparing Example 2 and Example 3, the difference in the proportion of the shaded area is 0.05%, which is not significant. However, the current collection unit 200 in Example 2 is 24×15, which is more in number than that in Example 3. The size of the current collection unit 200 is reduced, and the corresponding battery performance is improved to a relatively high level, with the efficiency increased by 1.65%. Continuing to reduce the side length of the Cairo pentagon structure 211 and the width of the current extraction grid line 210 (i.e., Example 1), the number of the current collection units 200 continues to increase to 24×17, and the size of the current collection unit 200 continues to decrease. The corresponding battery performance is further improved, and the battery efficiency reaches 25.76%, which is also greatly improved compared with the traditional straight grid lines.

[0112] 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", 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.

[0113] In the description of the present invention, it should be understood that the terms "comprising" and "having" used herein and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0114] Unless otherwise clearly defined and limited, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be directly connected, or indirectly connected through an intermediate medium, and can be the internal connection of 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. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A solar cell, characterized in that: include: Silicon wafer (100); A plurality of current collecting units (200), the current collecting units (200) being distributed on the silicon wafer (100) in a manner of M rows and N columns and electrically connected to the silicon wafer (100), the M being greater than 2, the N being greater than 2, and two adjacent current collecting units (200) being electrically connected; Each of the current collecting units (200) comprises: A plurality of groups of current extraction grid lines (210), each group of current extraction grid lines (210) being connected end to end in sequence to form a Cairo pentagonal structure (211), and the Cairo pentagonal structures (211) being spliced ​​with each other; A current collecting electrode (220) is electrically connected to the current extracting grid lines (210), and one current collecting electrode (220) is provided between at least one group of two connected current extracting grid lines (210).

2. The solar cell according to claim 1, characterized in that: Two adjacent Cairo pentagonal structures (211) share the same current extraction gate line (210).

3. The solar cell according to claim 1 or 2, characterized in that: Two adjacent current collection units (200) share the same current derivation grid line (210).

4. The solar cell according to claim 3, characterized in that: Two adjacent current collecting units (200) are electrically connected via the current collecting electrode (220), and share the current collecting electrode (220) at this location.

5. The solar cell according to claim 1 or 2, characterized in that: Each of the current collection units (200) comprises four Cairo pentagonal structures (211), and two adjacent Cairo pentagonal structures (211) share the same current extraction gate line (210).

6. The solar cell according to claim 5, characterized in that: The Cairo pentagonal structure (211) includes four long sides and one short side (211e) connected end to end in sequence, and the ratio of the length of the long side to the length of the short side (211e) is 7. The solar cell according to claim 6, characterized in that: The four long sides are respectively a first long side (211a), a second long side (211b), a third long side (211c) and a fourth long side (211d); the first long side (211a), the second long side (211b), the third long side (211c) and the fourth long side (211d) are connected end to end in sequence; and both ends of the short side (211e) are respectively connected to the first long side (211a) and the fourth long side (211d) to form a closed Cairo pentagon structure (211); The angle between the first long side (211a) and the second long side (211b) is a first angle, the angle between the second long side (211b) and the third long side (211c) is a second angle, the angle between the third long side (211c) and the fourth long side (211d) is a third angle, the angle between the fourth long side (211d) and the short side (211e) is a fourth angle, and the angle between the short side (211e) and the first long side (211a) is a fifth angle; The first angle is equal to the third angle, and the second angle is equal to the fourth angle and the fifth angle.

8. The solar cell according to claim 7, characterized in that: The angle between the first angle and the third angle is 90°, and the angle between the second angle, the fourth angle and the fifth angle is 120°.

9. The solar cell according to claim 1 or 2, characterized in that: The current collecting electrode (220) is circular, and the diameter of the current collecting electrode (220) is 0.060 mm-0.160 mm.

10. The solar cell according to claim 1 or 2, characterized in that: The current extraction grid line (210) has a width of 0.015 mm to 0.040 mm and a height of 0.015 mm to 0.040 mm.

11. The solar cell according to claim 6, characterized in that The length of the silicon wafer (100) is A, the width is B, the long side of the Cairo pentagonal structure (211) is x, and the short side (211e) is The M satisfies the following relationship: The N satisfies the following relationship:

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