Solar cells and solar cell modules

Abstract

The present invention provides a solar cell and a solar cell module. The solar cell comprises a silicon wafer and an electrode arranged on the silicon wafer. The electrode comprises a fine grid line arranged on the front of the silicon wafer. The fine grid line is arranged in a polygonal grid shape and is evenly distributed on the front of the silicon wafer. The electrode also comprises at least two front main grids arranged on the front of the silicon wafer and connected to the fine grid line, and a single front main grid is composed of a plurality of point-shaped welding electrodes. The solar cell and the solar cell module of the present invention can not only ensure power output, but also have low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power generation, and in particular to a solar cell sheet and a solar cell assembly. Background Art

[0002] At present, the industrialization technology of crystalline silicon solar cells is very mature. However, compared with conventional energy sources, lower power generation efficiency and relatively high costs restrict its development. Among the factors that affect power generation efficiency, the grid lines used to collect current on the cell are one of the key factors. Grid lines are usually divided into fine grid lines and front main grid lines. The fine grid lines are mainly used to collect current, while the front main grid lines collect current. However, because the grid lines are usually made of silver paste printing, printing defects such as virtual printing and broken grids are prone to occur, which will significantly affect the power of the cell. In addition, the main grid on the traditional cell is set in a single way, and the welding operation is more troublesome.

[0003] Therefore, it is necessary to provide an improved solar cell and solar cell assembly to solve the above problems. Summary of the invention

[0004] The object of the present invention is to provide a solar cell sheet and a solar cell assembly which can ensure power output and have low cost.

[0005] To achieve the above-mentioned purpose of the invention, the present invention provides a solar cell, including a silicon wafer and an electrode arranged on the silicon wafer, the electrode including fine grid lines arranged on the front side of the silicon wafer, the fine grid lines are arranged in a polygonal grid shape and are evenly distributed on the front side of the silicon wafer, the electrode also includes at least two front main grids arranged on the front side of the silicon wafer and connected to the fine grid lines, and a single front main grid is composed of a plurality of point-shaped welding electrodes.

[0006] As a further improvement of the present invention, the front main grid includes a first main grid and a second main grid extending along the silicon wafer in the horizontal and longitudinal directions respectively, the first main grid and the second main grid are both composed of a plurality of point-shaped welding electrodes, and the distance between two adjacent welding electrodes in the first main grid or the second main grid is smaller than the distance between two adjacent first main grids or two adjacent second main grids.

[0007] As a further improvement of the present invention, the number of the first bus bars extending transversely and the second bus bars extending longitudinally are the same and cross each other perpendicularly, and the number of spot welding electrodes on a single first bus bar is greater than the number of second bus bars intersecting perpendicularly with the first bus bars.

[0008] As a further improvement of the present invention, the solar cell also includes an aluminum back field and a back main grid arranged on the back of the silicon wafer. The distribution of the back main grid is the same as that of the front main grid, that is, it also includes the first main grid and the second main grid extending horizontally and vertically along the silicon wafer respectively.

[0009] As a further improvement of the present invention, the fine grid lines are arranged in a grid shape by connecting a plurality of quadrilaterals with common edges, and the welding electrodes are arranged at the intersections of four adjacent quadrilaterals in the fine grid lines.

[0010] As a further improvement of the present invention, the fine grid lines are arranged in a grid shape by connecting a plurality of hexagons with common edges, and the welding electrodes are arranged at the intersections of three adjacent hexagons in the fine grid lines.

[0011] As a further improvement of the present invention, the fine grid line includes a first fine grid formed by connecting a plurality of octagons and quadrilaterals to form a grid, and the welding electrode is printed in the quadrilateral in the first fine grid and connected to the first fine grid.

[0012] As a further improvement of the present invention, the welding electrode is square and arranged in the middle position of the quadrilateral in the first fine grid, and the length of each side of the welding electrode is smaller than the corresponding length of the quadrilateral in the first fine grid. The fine grid line also includes a second fine grid connecting the four corners of the welding electrode and the four corners of the quadrilateral in the first fine grid.

[0013] As a further improvement of the present invention, the welding electrode is arranged in a square shape, and the side length is set to 0.6-1.5 mm.

[0014] As a further improvement of the present invention, the welding electrodes are printed on the silicon wafer using silver paste, and a plurality of dot-shaped depressions are formed on each of the welding electrodes.

[0015] As a further improvement of the present invention, the point-shaped depressions are evenly arranged on the welding electrode, and the side length of the point-shaped depressions is set to 0.01-0.06 mm.

[0016] As a further improvement of the present invention, the printing height of the main body parts of the welding electrode except the dot-shaped recessed parts is 10-15 um, and the height of the dot-shaped recessed parts compared to the surface of the silicon wafer is 0-8 um.

[0017] As a further improvement of the present invention, the width of the fine gate line is 25um to 45um.

[0018] To achieve the above-mentioned purpose, the present invention also provides a solar cell assembly, comprising at least two battery strings and panels and back panels encapsulated on both sides of the battery strings with encapsulation films, each of the battery strings comprising at least one of the above-mentioned solar cells.

[0019] As a further improvement of the present invention, the battery strings extend in a straight line, and the solar cells are located at the beginning and / or the end of each battery string.

[0020] As a further improvement of the present invention, the solar cells in the same battery string are connected by a longitudinally extending welding strip; two adjacent battery strings are connected by a transversely extending welding strip, and one end of the transversely extending welding strip is welded to the light-receiving side of one battery string, and the other end is welded to the backlight side of an adjacent battery string.

[0021] As a further improvement of the present invention, each solar cell of each battery string is arranged as the solar cell described above, and two adjacent solar cells in each battery string are respectively connected in series with a second main grid located on the front and back sides of the silicon wafer by a welding ribbon, and two adjacent battery strings are connected in series with a first main grid located on the front and back sides of two adjacent solar cells located at the corresponding ends by a welding ribbon.

[0022] The beneficial effects of the present invention are as follows: on the one hand, the fine grid lines are arranged in a polygonal grid shape and evenly distributed on the front side of the silicon wafer, so that current can be collected to a greater extent. At the same time, the polygonal grid-shaped mutual conduction arrangement can ensure that even if the grid lines are printed in a virtual manner or the lines are broken, it will basically not affect the power of the battery cell; on the other hand, the welding electrodes arranged in a dot-like interval can effectively reduce the shading area of ​​the solar cell, and at the same time can also reduce the stress when connected to the welding tape and reduce the risk of cracking; and the loss of printed silver paste can be saved to the greatest extent, thereby reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a top view of a preferred embodiment of the solar cell of the present invention.

[0024] Figure 2 yes Figure 1 Bottom view of the solar cell shown.

[0025] Figure 3 yes Figure 1 Magnified view of the circled area.

[0026] Figure 4 yes Figure 1 An enlarged view of a welded electrode on a solar cell is shown.

[0027] Figure 5 It is a top view of another preferred embodiment of the solar cell of the present invention.

[0028] Figure 6 It is a partial structural schematic diagram of another preferred embodiment of the solar cell of the present invention.

[0029] Figure 7It is a partial connection diagram of a preferred embodiment of a battery string in a solar cell assembly of the present invention. Specific embodiments

[0030] The present invention will be described in detail below in conjunction with the embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural or functional changes made by a person skilled in the art based on these embodiments are all within the protection scope of the present invention.

[0031] Please refer to Figures 1 to 4 FIG. 1 is a preferred embodiment of a solar cell 100 of the present invention.

[0032] like Figure 1 and Figure 2 As shown, the solar cell 100 of the present invention comprises a silicon wafer 1 and an electrode disposed on the silicon wafer 1. The electrode comprises a fine grid line 2 disposed on the front of the silicon wafer 1 and at least two front main grids 3 connected to the fine grid line 2. The solar cell 100 further comprises an aluminum back field 4 and a back main grid 5 disposed on the back of the silicon wafer 1. The width of the fine grid line 2 is 25um to 45um.

[0033] Among them, Figure 1 As shown, the fine grid lines 2 in the present invention are arranged in a polygonal grid shape and are evenly distributed on the front side of the silicon wafer 1, thereby being able to collect current to a greater extent. At the same time, the polygonal grid shape is used for mutual conduction, so that even if the grid lines are printed in a virtual manner or broken, it will basically not affect the power of the battery cell.

[0034] A single front main grid 3 is composed of a plurality of dot-shaped welding electrodes 30, and the plurality of welding electrodes 30 are arranged at intervals in the extension direction of the front main grid 3. The front main grid 3 includes a plurality of first main grids 31 and a plurality of second main grids 32 extending transversely and longitudinally along the silicon wafer 1, respectively, and the number of the transversely extending first main grids 31 and the longitudinally extending second main grids 32 is the same and intersects each other perpendicularly; in this embodiment, four main grids are respectively arranged, and of course, they can also be adjusted according to needs. The distribution of the back main grid 5 is the same as that of the front main grid 3, that is, it also includes a plurality of the first main grids 31 and a plurality of the second main grids 32 extending transversely and longitudinally along the silicon wafer 1, respectively. Such an arrangement can greatly facilitate welding, and the solar cell 100 can realize bidirectional welding, and there is no need to deliberately adjust the placement direction of the solar cell 100 during the string welding process.

[0035] Each of the first main grid 31 and the second main grid 32 is composed of a plurality of dot-shaped welding electrodes 30; with this arrangement, on the one hand, bidirectional welding of the solar cell 100 of the present invention can be achieved; on the other hand, the dot-shaped welding electrodes 30 arranged at intervals can effectively reduce the shading area of ​​the solar cell 100; on the other hand, the dot-shaped welding electrodes 30 replace the existing linear main grid, and can also reduce the stress when connected to the welding strip and reduce the risk of cracking; on the other hand, it can also save the loss of printed silver paste to the greatest extent and reduce costs.

[0036] Furthermore, in the present invention, the distribution arrangement of the plurality of first main grids 31 in the transverse direction of the silicon wafer 1 is the same as the distribution arrangement of the plurality of second main grids 32 in the longitudinal direction of the silicon wafer 1, so that the solar cell 100 of the present invention can be welded arbitrarily without distinguishing directions during welding, thereby reducing the workload of testing and sorting of solar cell cells and assembly welding.

[0037] In the present invention, the distance between two adjacent welding electrodes 30 in the first main grid 31 or the second main grid 32 is smaller than the distance between two adjacent first main grids 31 or two adjacent second main grids 32, and the number of point welding electrodes 30 on a single first main grid 31 is greater than the number of second main grids 32 perpendicularly intersecting the first main grid 31; that is, the welding electrodes 30 on each first main grid 31 and the second main grid 32 are distributed more to collect current to a greater extent and ensure welding with the welding strip. In addition, the number of first main grids 31 and second main grids 32 is relatively small to ensure the light receiving area.

[0038] Furthermore, combined with Figure 1 and Figure 3 As shown, in this embodiment, the fine gate line 2 includes a first fine gate 21 that is arranged in a grid shape by connecting a plurality of octagons and quadrilaterals with common edges; specifically, in the horizontal and vertical directions of the silicon wafer 1, the octagons and quadrilaterals are arranged in an alternating and common-edge-connected manner, so that the four sides of each quadrilateral are connected with the four surrounding octagons with common edges.

[0039] The welding electrode 30 is printed and arranged in the quadrilateral in the aforementioned first fine grid 21, and is connected to the first fine grid 21. Specifically, the welding electrode 30 is arranged in a square shape in the middle of the quadrilateral in the first fine grid 21, and the length of each side of the welding electrode 30 is smaller than the corresponding length of the quadrilateral in the first fine grid 21. The fine grid line 2 also includes a second fine grid 22 connecting the four corners of the welding electrode 30 and the four corners of the quadrilateral in the first fine grid 21, thereby facilitating the collection of current to the greatest extent and with the least risk.

[0040] Furthermore, the welding electrode 30 is provided in a square entity shape, and the side length is set to 0.6 mm to 1.5 mm, so as to minimize the printing cost on the basis of ensuring welding with the welding strip.

[0041] Combination Figure 1 , Figure 3 and Figure 4 As shown, the welding electrode 30 is printed on the silicon wafer 1 using silver paste, and a plurality of dot-shaped depressions 301 are formed on each welding electrode 30, that is, the welding electrode 30 is designed to be concave-convex, so that when the solar cell 100 of the present invention is welded to the welding ribbon, the contact part between the solder and the welding electrode 30 is not on the same plane, but in a bumpy state, which increases the contact area and contact effect between the two, so that a certain pulling force can still be guaranteed when the area of ​​the welding electrode 30 is small. In this embodiment, the dot-shaped depressions 301 are evenly arranged on the welding electrode 30, and the side length of the dot-shaped depressions 301 is set to 0.01~0.06mm.

[0042] Preferably, the printing height of the main body parts of the welding electrode 30 except the dot-shaped recess 301 is 10-15 um, and the height of the dot-shaped recess 301 compared to the surface of the silicon wafer 1 is 0-8 um.

[0043] See also Figure 5 As shown, as another preferred embodiment of the present invention, the fine grid lines 2 can also be arranged in a grid shape by connecting a number of quadrilaterals with common sides. In this case, the welding electrode 30 is arranged at the intersection of four adjacent quadrilaterals in the fine grid lines 2, and the welding electrode 30 can also be connected to the fine grid lines 2 in a multi-directional manner.

[0044] See also Figure 6 As shown, as another preferred embodiment of the present invention, the fine grid lines 2 are arranged in a grid shape by connecting a number of hexagons with common edges, and the welding electrodes 30 are arranged at the intersections of three adjacent hexagons in the fine grid lines 2, which can also achieve multi-directional conduction and reduce the impact of printing voids, broken wires, etc. on the power of the battery cell.

[0045] See also Figure 7 In combination with the structural design of the solar cell 100, the present invention further provides a solar cell assembly 600, which includes at least two battery strings and panels and back panels encapsulated on both sides of the battery strings by encapsulation films. Each of the battery strings includes at least one solar cell 100.

[0046] The battery string extends in a straight line, and the solar cell 100 is located at the head and / or end of each battery string. Among them, the battery string located at the edge can only be provided with one solar cell 100 at the head or end position where it needs to be connected to the adjacent battery string, while the battery string located in the middle is provided with one solar cell 100 at the head and the end; such a configuration allows the solar cells in the same battery string to be connected through the longitudinally extending welding strip 6, and the two adjacent battery strings can be connected through the transversely extending welding strip 6, and one end of the transversely extending welding strip 6 is welded to the light-receiving side of one battery string, and the other end is welded to the backlight side of the adjacent battery string. In this way, the two adjacent battery strings can be connected directly through the welding strip 6 without the need for additional bus bar connection, which also saves the space required for arranging the bus bar.

[0047] Of course, each solar cell in each of the battery strings can also be arranged as the above-mentioned solar cell 100, in which case two adjacent solar cells 100 in each of the battery strings are respectively connected in series to the second main grid 32 located on the front and back sides of the silicon wafer 1 by using the longitudinally extending welding strip 6, and two adjacent battery strings are connected in series to the first main grid 31 located on the front and back sides of the two adjacent solar cells 100 located at the corresponding ends by using the transversely extending welding strip 6. In this way, of course, the two adjacent battery strings can also be directly connected by the welding strip 6, without the need for additional busbar connection, which also saves the space required for arranging the busbar.

[0048] In addition, when the distribution arrangement of the first main grids 31 in the transverse direction of the silicon wafer 1 is the same as the distribution arrangement of the second main grids 32 in the longitudinal direction of the silicon wafer 1, the solar cell 100 can be arranged arbitrarily, and the first main grids 31 and the second main grids 32 can be arbitrarily connected and arranged through the welding strips 6 according to the arrangement of the solar cell 100, thereby effectively saving operation time and cost.

[0049] The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention. They are not intended to limit the scope of protection of the present invention. All equivalent embodiments or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A solar cell comprising a silicon wafer and an electrode disposed on the silicon wafer, wherein the electrode comprises a fine grid line disposed on the front surface of the silicon wafer, characterized in that: The fine grid lines are arranged in a polygonal grid and are evenly distributed on the front side of the silicon wafer. The electrodes also include at least two front main grids arranged on the front side of the silicon wafer and connected to the fine grid lines. A single front main grid is composed of a number of dot-shaped welding electrodes. The fine grid lines include a first fine grid arranged in a grid shape using a number of octagons and quadrilaterals connected by common sides. The welding electrodes are printed in the quadrilaterals of the aforementioned first fine grids and are connected to the first fine grids. The front main grid only includes four first main grids and four second main grids extending along the silicon wafer in the horizontal and longitudinal directions respectively. The first main grid and the second main grid are both composed of a number of dot-shaped welding electrodes. The distance between two adjacent welding electrodes in the first main grid or the second main grid is smaller than the distance between two adjacent first main grids or two adjacent second main grids. The first main grid and the second main grid cross each other perpendicularly, and the number of dot-shaped welding electrodes on a single first main grid is greater than the number of second main grids that cross the first main grid perpendicularly.

2. The solar cell according to claim 1, characterized in that: The solar cell also includes an aluminum back field and a back main grid arranged on the back of the silicon wafer. The distribution of the back main grid is the same as that of the front main grid, that is, it also includes the first main grid and the second main grid extending horizontally and vertically along the silicon wafer respectively.

3. The solar cell according to claim 1, characterized in that: The welding electrode is square and arranged in the middle of the quadrilateral in the first fine grid, and the length of each side of the welding electrode is smaller than the corresponding side length of the quadrilateral in the first fine grid. The fine grid line also includes a second fine grid connecting the four corners of the welding electrode and the four corners of the quadrilateral in the first fine grid.

4. The solar cell according to claim 1, characterized in that: The welding electrode is arranged in a square shape, and the side length is arranged to be 0.6-1.5 mm.

5. The solar cell according to claim 1, characterized in that: The welding electrodes are printed on the silicon wafer using silver paste, and a plurality of dot-shaped depressions are formed on each of the welding electrodes.

6. The solar cell according to claim 5, characterized in that: The point-shaped depressions are evenly arranged on the welding electrode, and the side length of the point-shaped depressions is set to 0.01-0.06 mm.

7. The solar cell according to claim 5, characterized in that: The printing height of the main body parts of the welding electrode except the dot-shaped concave parts is 10-15 um, and the height of the dot-shaped concave parts compared with the surface of the silicon wafer is 0-8 um.

8. The solar cell according to claim 1, characterized in that: The width of the fine gate line is 25um to 45um.

9. A solar cell assembly, comprising at least two battery strings and panels and back panels encapsulated on both sides of the battery strings by encapsulation films, characterized in that: Each of the battery strings comprises at least one solar cell according to any one of claims 2 to 8.

10. The solar cell assembly according to claim 9, characterized in that: The battery strings extend in a straight line, and the solar cells are located at the beginning and / or the end of each battery string.

11. The solar cell assembly according to claim 10, characterized in that: The solar cells in the same battery string are connected by a longitudinally extending welding strip; two adjacent battery strings are connected by a transversely extending welding strip, and one end of the transversely extending welding strip is welded to the light-receiving side of one battery string, and the other end is welded to the backlight side of the adjacent battery string.

12. The solar cell assembly according to claim 11, characterized in that: Each solar cell of each of the battery strings is arranged as the solar cell as described in any one of claims 2 to 8, and two adjacent solar cells in each of the battery strings are connected in series with a second main grid located on the front and back sides of the silicon wafer respectively by welding ribbons, and two adjacent battery strings are connected in series with a first main grid located on the front and back sides of two adjacent solar cells located at the corresponding ends by welding ribbons.

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