Strip cell, solar cell, photovoltaic module and manufacturing method thereof

Abstract

The present invention discloses a strip-shaped cell, a solar cell, a photovoltaic module and a manufacturing method thereof, wherein the strip-shaped cell has a long side and a short side, and the front of the strip-shaped cell has a front main grid arranged along the edge of the short side. The short sides of the long strip-shaped cell can be overlapped and connected, the welding part can be greatly shortened, and the cell efficiency can be improved.

Description

Technical Field

[0001] The invention relates to a strip-shaped battery sheet, a solar battery sheet, and a photovoltaic module connected by the strip-shaped battery sheets. The invention also relates to a method for manufacturing the photovoltaic module, and belongs to the technical field of solar power generation. Background Art

[0002] Traditional solar cells are connected by bus bars. The use of a large number of bus bars will increase the internal consumption of solar panels and reduce the conversion efficiency of solar panels.

[0003] In order to improve the conversion efficiency of solar panels, shingling technology has emerged. In layman's terms, shingling technology is to cut the cells into small pieces, overlap the edges of the cut pieces and connect them to make photovoltaic modules, and then press the photovoltaic modules into modules after series and parallel layout. The reasonable application of shingling technology can place more cells within the wired range, while reducing the line loss of solar panels and greatly improving the output power of the modules.

[0004] Take the example of a five-cell solar cell. Figure 1 The front electrode of the cell 99 includes a main grid 97 and a plurality of auxiliary grid lines 95. The main grid 97 is at the edge of the cell 99 and serves as a welding point for connecting the cell 99 with another cell. Figure 2 The back electrode of the battery cell 99 includes a back electrode main grid 93 and a back secondary electrode 91 . The back electrode main grid 93 corresponds to the front main grid 97 and is arranged at the edge of the battery. A plurality of back secondary electrodes 91 are distributed at intervals on the back of the battery cell 99 .

[0005] The front and back electrodes are used together. When the assembly is welded, the main grid 97 of the front electrode of one battery cell 99 is connected to the main grid 93 of the back electrode of another battery cell through conductive glue. The back secondary electrode 91 is used as a connection point with the assembly bus bar and is only used in the first battery cell 99 and the last battery cell 99 in a string of batteries.

[0006] Since the main grid of the front electrode of the existing solar cell is designed at the edge of the long side of the cell, multiple main grids need to be set on the front of the cell before cutting. Since the main grid serves as the welding point with another cell, it must be ensured to have sufficient width, which will cause the shading area of ​​the cell to increase sharply and the amount of silver paste used will also increase. Summary of the invention

[0007] The object of the present invention is to provide a strip-shaped battery cell that can improve efficiency.

[0008] To achieve the above-mentioned object of the invention, the present invention provides a strip-shaped battery sheet, wherein the strip-shaped battery sheet has a long side and a short side, and the front side of the strip-shaped battery sheet has a front main grid arranged along the edge of the short side.

[0009] As a further improvement of an embodiment of the present invention, the line width of the front main grid is 0.5 mm to 3 mm.

[0010] As a further improvement of an embodiment of the present invention, the front side of the strip-shaped solar cell is further provided with a plurality of secondary grid lines for collecting current and auxiliary grid lines connecting the secondary grid lines and the front main grid.

[0011] As a further improvement of an embodiment of the present invention, the length of the auxiliary grid line is N times the length of the front main grid, and N is an integer not less than 4.

[0012] As a further improvement of an embodiment of the present invention, the line width of the auxiliary grid line is smaller than the line width of the front main grid, and the line width of the auxiliary grid line is 0.3 mm to 2 mm.

[0013] As a further improvement of an embodiment of the present invention, the secondary grid lines are arranged parallel to the front main grid, and the auxiliary grid lines vertically connect the secondary grid lines and the front main grid.

[0014] As a further improvement of an embodiment of the present invention, there is one auxiliary grid line, and it is located in the middle of the strip-shaped battery cell in the extending direction of the short side.

[0015] As a further improvement of an embodiment of the present invention, at least two auxiliary grid lines are arranged at intervals in the extension direction of the short side of the strip-shaped battery cell, and at least two auxiliary grid lines are connected in series with all the secondary grid lines in the extension direction of the long side of the strip-shaped battery cell.

[0016] As a further improvement of an embodiment of the present invention, the line width of the auxiliary grid line gradually decreases from an end connected to the front main grid toward an end away from the front main grid.

[0017] As a further improvement of an embodiment of the present invention, the line width of the auxiliary grid line at one end connected to the front main grid is 0.5 mm to 3 mm, and the line width of the end away from the front main grid is 0.01 to 0.2 mm.

[0018] As a further improvement of an embodiment of the present invention, a back main grid is provided on the side edge opposite to the back side of the strip-shaped battery cell and the front main grid.

[0019] As a further improvement of an embodiment of the present invention, a back side welding pad is further provided on the back side of the strip-shaped battery cell. The back side welding pad is perpendicular to the back side main grid and is provided in the middle position of the strip-shaped battery cell.

[0020] As a further improvement of an embodiment of the present invention, the line width of the back side welding pad is 0.5 mm to 3 mm, and the line length is 3 mm to 30 mm.

[0021] Compared with the prior art, the beneficial effect of the present invention is that since the front side of the strip-shaped battery cell has a front main grid arranged along the edge of the short side, the short side overlapping connection of the long strip-shaped battery cell can be achieved, the welding part can be greatly shortened, and the battery efficiency can be improved.

[0022] Another object of the present invention is to provide a solar cell sheet, the solar cell sheet comprising a plurality of strip-shaped solar cells that are integrally connected and not separated, the strip-shaped solar cells being arranged as described in any one of the above items.

[0023] Compared with the prior art, the beneficial effects of the present invention are: it can realize the overlapping connection of the short sides of the long strip battery sheets, can greatly shorten the welding part, and improve the battery efficiency.

[0024] Another object of the present invention is to provide a photovoltaic module, including a plurality of battery strings, each of which includes a plurality of strip-shaped battery cells stacked and connected at the edges by conductive glue, the strip-shaped battery cells are arranged as described in any of the above items, and two adjacent strip-shaped battery cells are connected by stacking the short sides.

[0025] As a further improvement of an embodiment of the present invention, the length of the long side of the strip-shaped battery sheet is N times the length of the short side. In the plurality of battery strings, each N battery strings are connected in parallel via a bus bar, and N is an integer not less than 4.

[0026] Compared with the prior art, the beneficial effects of the present invention are: it can realize the overlapping connection of the short sides of the long strip battery sheets, can greatly shorten the welding part, and improve the battery efficiency.

[0027] Another object of the present invention is to provide a method for manufacturing a photovoltaic module, comprising the following steps:

[0028] S1: providing a silicon wafer, and setting a front main grid on one edge of the front side of the silicon wafer;

[0029] S2: cutting a groove on the silicon wafer in a direction perpendicular to the front main grid, wherein the cutting groove extends from the edge of the silicon wafer where the front main grid is located to the edge of the silicon wafer on the other side parallel to it;

[0030] S3: performing a splitting process on the silicon wafer, so that the silicon wafer is split along the cutting groove to obtain a plurality of strip-shaped battery cells, and the short side edges of the strip-shaped battery cells have the front main grid;

[0031] S4: Overlapping and connecting the short edges of the strip-shaped battery sheets to form a battery series, and manufacturing a photovoltaic module.

[0032] As a further improvement of an embodiment of the present invention, before the splitting process, a conductive glue is pre-set on the front or back side of the silicon wafer, and the conductive glue is distributed on one side edge of the silicon wafer in a direction parallel to the front main grid.

[0033] As a further improvement of an embodiment of the present invention, the conductive glue is printed onto the front main grid on the front side of the silicon wafer by printing.

[0034] As a further improvement of an embodiment of the present invention, after the splitting process, a conductive glue is provided on the short side edge of each battery strip.

[0035] Compared with the prior art, the beneficial effect of the present invention is that the manufacturing method can realize the overlapping connection of the short sides of the long strip battery sheets, which can greatly shorten the welding part and improve the battery efficiency.

[0036] Another object of the present invention is to provide a method for manufacturing a photovoltaic module, comprising the following steps:

[0037] S1: providing a silicon wafer, wherein a front main grid and a plurality of secondary grid lines parallel to the front main grid are provided on the front side of the silicon wafer, and only one side edge of two oppositely disposed sides of the front side of the silicon wafer is provided with the front main grid;

[0038] S2: splitting the silicon wafer into equal pieces to obtain a plurality of strip-shaped solar cells, and dividing the front main grid into a plurality of equal pieces and respectively setting them on the short side edges of each strip-shaped solar cell.

[0039] S3: Connecting the strip-shaped solar cells in series to produce a photovoltaic module.

[0040] As a further improvement of an embodiment of the present invention, the equal splitting processing includes:

[0041] Use laser to carve several equally spaced cutting grooves on the silicon wafer in a direction perpendicular to the front main grid;

[0042] External force is applied to the silicon wafer to cause the silicon wafer to split along the cutting grooves to form a plurality of strip-shaped battery cells.

[0043] As a further improvement of an embodiment of the present invention, the cutting groove is formed on the back side of the battery cell.

[0044] As a further improvement of one embodiment of the present invention, a back main grid and a plurality of mutually parallel back welding pads are provided on the back side of the silicon wafer, and the back main grid is arranged on the edge of the silicon wafer on the other side opposite to the edge of the silicon wafer where the front main grid is located; the laser uses the back welding pad to locate the center line position between two adjacent back welding pads, and carves a cutting groove at this position.

[0045] Compared with the prior art, the beneficial effect of the present invention is that the manufacturing method can realize the overlapping connection of the short sides of the long strip battery sheets, which can greatly shorten the welding part and improve the battery efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is a schematic diagram of a front electrode of a solar cell in the prior art;

[0047] Figure 2 yes Figure 1 Schematic diagram of the back electrode of the solar cell shown;

[0048] Figure 3 is a schematic diagram of a front electrode of a solar cell provided in a first embodiment of the present invention;

[0049] Figure 4 is a schematic diagram of a front electrode of a sliced ​​battery provided in another embodiment of the present invention;

[0050] Figure 5 yes Figure 3 Schematic diagram of the back electrode of the solar cell shown;

[0051] Figure 6 This is a schematic diagram of a structure in which the short sides of sliced ​​batteries are overlapped and connected according to an embodiment of the present invention;

[0052] Figure 7 is a schematic diagram of a front electrode of a solar cell provided in a second embodiment of the present invention;

[0053] Figure 8 yes Figure 7 The schematic diagram of the structure of the short side overlapping connection of the solar cell shown

[0054] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same or similar components or parts are indicated by the same reference numerals in the accompanying drawings. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. For example, for the convenience of illustration, some dimensions of structures or parts may be appropriately exaggerated relative to other structures or parts. Therefore, the drawings are only used to illustrate the basic structure of the subject matter of the present application. DETAILED DESCRIPTION

[0055] The present invention will be described in detail below in conjunction with the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional changes made by a person skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0056] It should be understood that in the description of the present invention, the terms "first", "second", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include one or more of the features.

[0057] In the present invention, unless otherwise clearly stipulated and limited, a first feature being “on” or “under” a second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through another feature between them.

[0058] Figure 3 and Figure 4 Several strip-shaped battery cells 100 of the first embodiment of the present invention are shown, which are obtained by cutting and splitting the original solar cell 1000 into five equal parts. The original solar cell 1000 is laser-scribed to form several cutting grooves 152, so that the final split is separated to obtain five strip-shaped battery cells 100. The five strip-shaped battery cells 100 have the same structure. Since the strip-shaped battery cells 100 obtained by the equal-cutting are long strips, for the convenience of description, the name of the strip-shaped battery cell 100 is used in some paragraphs below to help understanding. The following description takes one of the strip-shaped battery cells 100 as an example.

[0059] It should be noted that before the solar cell 1000 is cut, it includes a plurality of strip-shaped solar cells 100 that are integrally connected and not separated. In other words, before the solar cell 1000 is cut, there is no gap on the surface, and the cutting groove 152 cannot be seen. Figure 3 In the figure, only five strip-shaped battery sheets 100 are put together, so there appears to be a gap.

[0060] Please combine Figure 3 and Figure 4 The strip-shaped battery cell 100 provided in the embodiment of the present invention includes a substrate, which is rectangular and includes a long side and a short side. The length of the long side of the strip-shaped battery cell is N times the length of the short side, and N is an integer not less than 4. The strip-shaped battery cell 100 has a first short side edge and a second short side edge.

[0061] The substrate includes a front surface 110 and a back surface 120, wherein a front electrode is disposed on the front surface 110 and a back electrode is disposed on the back surface 120. The front electrode includes a plurality of secondary grid lines 136 for collecting current, a front main grid 132 connected to the secondary grid lines 136, and the front main grid 132 is connected to the back electrode on another strip-shaped battery cell 100. In this embodiment, the front electrode further includes an auxiliary grid line 131, and the front main grid 132 is connected to the secondary grid line 136 through the auxiliary grid line 131.

[0062] Therefore, in the strip-shaped battery cell 100 of this embodiment, the auxiliary grid lines 136 collect the photogenerated current on the surface of the substrate, the auxiliary grid lines 131 are connected to the auxiliary grid lines 136 and collect the current on all the auxiliary grid lines 136, and the front main grid 132 connects the current on the auxiliary grid lines 131 to another strip-shaped battery cell 100. Under normal circumstances, the front main grid 132 is electrically connected to the back electrode of another strip-shaped battery cell 100 to achieve current connectivity, thereby realizing current collection and transmission.

[0063] In this embodiment, the substrate is a silicon wafer. If possible, the substrate can also be made of other materials. The material of the substrate is not the focus of the present invention. All solutions that are the same or similar to this embodiment are included in the protection scope of the present invention.

[0064] See also Figure 3 In this embodiment, preferably, a plurality of secondary grid lines 136 are arranged in parallel and spaced apart on the front surface 110 and are set at equal intervals.

[0065] Specifically, a plurality of auxiliary grid lines 136 extend from one long side of the substrate to the other long side, and the width of the plurality of auxiliary grid lines 136 is substantially equal to the width of the substrate. The plurality of auxiliary grid lines 136 are arranged in parallel and spaced apart along the length direction of the substrate. Preferably, the plurality of auxiliary grid lines 136 are arranged in parallel and spaced apart at equal distances, so as to better collect the photocurrent on the substrate.

[0066] In this embodiment, the auxiliary gate line 131 is preferably perpendicular to the secondary gate line 136 .

[0067] Therefore, since several auxiliary gate lines 136 are parallel, the auxiliary gate line 131 is perpendicular to the auxiliary gate line 136, that is, the auxiliary gate line 131 is perpendicular to all the auxiliary gate lines 136. Therefore, one auxiliary gate line 131 can be vertically connected to the auxiliary gate line 136, and one auxiliary gate line 131 can collect the current of all the auxiliary gate lines 136. The structural design is very clever.

[0068] In this embodiment, the number of auxiliary grid line 131 is one, and it is located in the middle of the strip-shaped battery cell 100 in the short side extension direction. One end of the auxiliary grid line 131 is connected to the front main grid 132 on the first short side edge, and the other end extends to the second short side edge.

[0069] Since the auxiliary grid line 131 is located in the middle of the strip-shaped battery cell 100 , the auxiliary grid line 131 can collect the current on the secondary grid lines 136 on both sides thereof at the same time, thereby greatly reducing resistance loss and improving collection efficiency.

[0070] See also Figure 4In another embodiment of the present invention, the number of auxiliary grid lines 131 is two, and the two auxiliary grid lines 131 are connected in series with the auxiliary grid lines 136 along the long edges on both sides of the front surface 110. The two auxiliary grid lines 131 can better prevent grid breakage. Those skilled in the art can imagine that the auxiliary grid lines 131 are arranged at intervals of at least two in the direction of the short side extension of the strip-shaped battery sheet 100, and at least two auxiliary grid lines 131 are connected in series with all the auxiliary grid lines 136 in the direction of the long side extension of the strip-shaped battery sheet 100.

[0071] In this embodiment, the length of the auxiliary gate line 131 is N times the length of the front main gate 132 , where N is an integer not less than 4.

[0072] In this embodiment, the width of the auxiliary gate line 131 is between 0.3 mm and 2 mm. This value is only exemplary and does not constitute a limitation to the present invention. Any solution that is the same or similar to this embodiment is included in the protection scope of the present invention.

[0073] Please return Figure 3 In this preferred embodiment, the front main grid 132 is perpendicular to the auxiliary grid line 131, and the two form a T-shape.

[0074] The front main grid 132 is perpendicular to the auxiliary grid line 131 . Compared with other angles between the front main grid 132 and the auxiliary grid line 131 , not only the structure is regular and the volume of the substrate is reduced, but also the efficiency of the strip-shaped battery cell 100 can be improved.

[0075] In this embodiment, preferably, the midpoint of the front main grid 132 is connected to the end point of the auxiliary grid line 131 .

[0076] Thus, the current on the auxiliary grid line 131 can flow to the front main grid 132 , thereby improving the efficiency of the strip-shaped battery cell 100 .

[0077] As mentioned above, the substrate is rectangular in shape as a whole. In this embodiment, the front main grid 132 is disposed close to the short side edge of the rectangular substrate. Specifically, the front main grid 132 is disposed close to the first short side edge on the front side 110 of the rectangular substrate.

[0078] In this embodiment, the width of the front main grid 132 is between 0.5 mm and 3 mm. This value is merely exemplary and does not constitute a limitation to the present invention. Any solution that is the same or similar to this embodiment is included in the protection scope of the present invention.

[0079] See also Figure 5 In this embodiment, the back electrode on the back side 120 includes a back main grid 141 and a back welding pad 142. The back main grid 141 is connected to the front main grid 132 of another strip-shaped battery cell 100, and the back welding pad 142 is connected to the welding strip.

[0080] When the strip-shaped battery sheet 100 of this embodiment is used, the back main grid 141 is connected to the front main grid 132 of another strip-shaped battery sheet 100 by conductive adhesive. Of course, the two can also be connected and conductive in other ways, and all solutions that are the same or similar to this embodiment are covered within the protection scope of the present invention.

[0081] Those skilled in the art can imagine that when strip-shaped battery cells form a battery string, the back side of the strip-shaped battery cell in the middle of the battery string may not need to be provided with a back main grid. In this case, the back side is an all-aluminum back field, and the front main grid and the edge of the aluminum back field are connected by stacking with conductive glue, which can also achieve the purpose of the present invention.

[0082] See also Figure 6 Specifically, in this embodiment, the front main grid 132 is located on the front of the strip battery cell 100 and is arranged near the first short side edge, the back side 120 is rectangular, and the back main grid 141 is located on the back side 120 of the strip battery cell 100 and is arranged near the second short side edge. The front main grid 132 and the back main grid 141 connecting the strip battery cells 100 are respectively located on the two short side edges of the substrate, and the front main grid 132 on the first short side edge of the front side 110 of a strip battery cell 100 is connected to the back main grid 141 on the second short side edge of the back side 120 of the next strip battery cell 100... Repeatedly, the short sides of the long strip battery cells can be overlapped and connected to form a battery series, which can greatly shorten the welding parts and improve the battery efficiency.

[0083] The shape of the back busbar 141 is consistent with the shape and area of ​​the front busbar 132 , so that the back busbar 141 of one strip-shaped battery cell 100 can be connected to the front busbar 132 of another strip-shaped battery cell 100 in a regular manner.

[0084] Please return Figure 5 In this embodiment, the length extension direction of the back welding pad 142 is perpendicular to the length extension direction of the back main grid 141. Preferably, the back welding pad 142 is arranged at the center position of the back side 120, that is, the back welding pad 142 is located on the center line of the first short side edge and the second short side edge. Of course, those skilled in the art can arrange the back welding pad 142 at other positions of the back side 120 as needed, and all solutions that are the same or similar to this embodiment are covered within the protection scope of the present invention.

[0085] The back welding pad 142 has a length of 3 mm to 30 mm and a width of 0.5 mm to 3 mm. These values ​​are merely exemplary and do not constitute a limitation of the present invention. Any solution that is the same or similar to the present embodiment is within the protection scope of the present invention.

[0086] Therefore, this embodiment also provides a photovoltaic module, including a plurality of battery strings, each battery string includes a plurality of strip-shaped battery cells 100 connected at the edges by stacking with conductive adhesive, and two adjacent strip-shaped battery cells 100 are connected by stacking the short sides.

[0087] Specifically, the photovoltaic module is formed by connecting two or more strip-shaped cells 100 in series. Specifically, the front main grid 132 of the first strip-shaped cell 100 is connected to the back main grid 141 of the second strip-shaped cell 100, and the front main grid 132 of the second strip-shaped cell 100 is connected to the back main grid 141 of the third strip-shaped cell 100. Repeatedly, two or more strip-shaped cells 100 can be connected in series to form a battery string, and the back welding pads 142 of the first strip-shaped cell 100 and the last strip-shaped cell 100 in the battery string are connected to the welding strip. The structure is simple and easy to use.

[0088] The following describes a method for manufacturing a photovoltaic module provided by an embodiment of the present invention, and the manufacturing method comprises the following steps:

[0089] S1: providing a silicon wafer, and setting a front main grid 132 on one edge of the front side of the silicon wafer;

[0090] S2: cutting a cutting groove 152 on the silicon wafer in a direction perpendicular to the front main grid 132, the cutting groove 152 extending from the edge where the front main grid 132 is located to the other side edge parallel to it;

[0091] S3: performing a splitting process on the silicon wafer, so that the silicon wafer is split along the cutting groove 152 to obtain a plurality of strip-shaped battery cells 100, and the short side edges of the strip-shaped battery cells 100 have a front main grid 132;

[0092] S4: overlapping and connecting the short edges of the strip-shaped battery sheets 100 to form battery strings, and manufacturing a photovoltaic module.

[0093] In this embodiment, the silicon wafer in step S1 is a silicon wafer that has been processed by texturing, diffusion, post-cleaning, coating, etc. The cutting groove is the gap mentioned above.

[0094] In this embodiment, in step S2, a laser is usually used to scribe a cutting groove 152 on the back side 120 of the silicon wafer and directly cut off the related gate lines.

[0095] In this embodiment, preferably, before the splitting process, a conductive glue is pre-placed on the front or back side of the silicon wafer, and the conductive glue is distributed on one side edge of the silicon wafer in a direction parallel to the front main grid 132 .

[0096] In this embodiment, the conductive glue is preferably printed onto the front main grid 132 on the front side of the silicon wafer.

[0097] In this embodiment, preferably, after the splitting process, a conductive adhesive is provided on the short side edge of each battery strip 100 .

[0098] The specific embodiment of the present invention also provides a method for manufacturing a photovoltaic module, comprising the following steps:

[0099] S1: A silicon wafer is provided, wherein a front main grid 132 and a plurality of secondary grid lines 136 parallel to the front main grid 132 are provided on the front side of the silicon wafer, and only one side edge of two oppositely disposed sides of the front side of the silicon wafer is provided with the front main grid 132;

[0100] S2: splitting the silicon wafer into equal pieces to obtain a plurality of strip-shaped solar cells, and dividing the front main grid 132 into a plurality of equal pieces and respectively setting them on the short side edge of each strip-shaped solar cell 100 .

[0101] S3: Connect the strip-shaped solar cells in series to produce a photovoltaic module.

[0102] In this embodiment, the equal splitting process includes: using a laser to carve a plurality of equally spaced cutting grooves 152 on the silicon wafer in a direction perpendicular to the front main grid 132, wherein the cutting grooves 152 divide the front main grid 132 into a plurality of equal segments;

[0103] External force is applied to the silicon wafer to cause the silicon wafer to split along the cutting grooves 152 to form a plurality of strip-shaped battery cells 100 .

[0104] In this embodiment, the cutting groove 152 is preferably formed on the back side of the battery cell.

[0105] In the preferred embodiment of the present invention, a back side main grid 141 and a plurality of mutually parallel back side welding pads 142 are provided on the back side 120 of the silicon wafer, and the back side main grid 141 is arranged on the edge of the silicon wafer on the other side opposite to the edge of the silicon wafer where the front side main grid 132 is located; the laser uses the back side welding pad 142 to locate the center line position between two adjacent back side welding pads 142, and carves a cutting groove 152 at this position.

[0106] Figure 7 and Figure 8 A solar cell sheet according to a second embodiment of the present invention is shown.

[0107] The following focuses on the differences between the solar cell of this embodiment and the solar cell of the first embodiment.

[0108] In the first embodiment, the width of the auxiliary gate line 131 remains unchanged.

[0109] See also Figure 7 In this embodiment, preferably, the width of the auxiliary gate line 231 gradually decreases in a direction away from the front main gate 232 .

[0110] That is to say, the width of the auxiliary grid line 231 is gradual. At a position close to the front main grid 232, the width of the auxiliary grid line 231 is larger, between 0.5-3 mm, and at a position far from the front main grid 232, the width of the auxiliary grid line 231 is smaller, between 0.01-0.2 mm.

[0111] It should be noted that this range of values ​​is merely exemplary and does not constitute a limitation on the present invention. Any solution that is the same or similar to the present embodiment is within the protection scope of the present invention.

[0112] Therefore, on the auxiliary grid line 231, the current is high at the position close to the front main grid 232, and low at the position far from the front main grid 232. Therefore, the gradual change of the width of the auxiliary grid line 231 can match the change of the current, further reducing the series resistance loss on the auxiliary grid line 231, improving the electrical performance of the battery; and also reducing the amount of silver paste used.

[0113] See also Figure 8 , is a partial enlarged view of the photovoltaic module described in the present invention, showing a schematic diagram of 10 columns (strings) of battery strings arranged in parallel. Due to space constraints, only two long strips of battery strips that overlap and connect with each other at the starting position of each column are shown in each battery string. In these two battery strips, the front main grid of the lower battery strip overlaps and connects with the back main grid of the back of the upper battery strip and is therefore blocked, and the front main grid of the upper battery sheet is blocked by a bus bar 235. The bus bar 235 connects the starting ends of the 10 columns of battery strings in series and makes the 10 columns of battery strings form a parallel relationship. Those skilled in the art know that the number of battery strings is not limited to 10, that is, in a number of battery strings, every N columns of battery strings are connected in parallel through the bus bar 235, and N is an integer not less than 4.

[0114] It is worth mentioning that in a preferred embodiment of the present invention, if each battery strip 100 is obtained by cutting the solar cell 1000 into N equal parts, then the bus bar 235 will be connected in parallel with N columns of battery strings. For example, if the solar cell is divided into 5 equal parts, the bus bar will be connected in parallel with 5 battery strings; if the solar cell is divided into 6 equal parts, the bus bar will be connected in parallel with 6 battery strings.

[0115] In this embodiment, when the length of the long side of the battery strip 100 is N times the length of the short side (N is an integer not less than 4), the bus bar 235 will connect N columns of battery strings in parallel.

[0116] It should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation mode may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0117] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods 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 photovoltaic module, comprising a plurality of battery strings, each of which comprises a plurality of strip-shaped battery sheets connected at the edges by means of conductive adhesive, wherein the strip-shaped battery sheets have a long side and a short side, and is characterized in that: The front side of the strip battery cell has a front main grid arranged along the edge of the short side, and the back side of the strip battery cell is provided with a back main grid on the side edge opposite to the front main grid. Two adjacent strip battery cells are connected by overlapping the short sides. Among the two adjacent strip battery cells, the front main grid of one strip battery cell is connected to the back main grid of the other strip battery cell; the front side of the strip battery cell is also provided with a plurality of auxiliary grid lines for collecting current and auxiliary grid lines connecting the auxiliary grid lines and the front main grid; the line width of the auxiliary grid line gradually decreases from the end connected to the front main grid toward the end away from the front main grid.

2. The photovoltaic module according to claim 1, characterized in that: The line width of the front main grid is 0.5 mm to 3 mm.

3. The photovoltaic module according to claim 1, characterized in that: The length of the auxiliary grid line is N times the length of the front main grid, where N is an integer not less than 4.

4. The photovoltaic module according to claim 1, characterized in that: The line width of the auxiliary grid line is smaller than the line width of the front main grid, and the line width of the auxiliary grid line is 0.3 mm to 2 mm.

5. The photovoltaic module according to claim 1, characterized in that: The secondary grid lines are arranged parallel to the front main grid, and the auxiliary grid lines are vertically connected to the secondary grid lines and the front main grid.

6. The photovoltaic module according to claim 5, characterized in that: There is one auxiliary grid line, and the auxiliary grid line is located in the middle of the strip-shaped battery sheet in the extending direction of the short side.

7. The photovoltaic module according to claim 5, characterized in that: At least two auxiliary grid lines are arranged at intervals in the extending direction of the short side of the strip-shaped battery sheet, and at least two auxiliary grid lines are connected in series with all the secondary grid lines in the extending direction of the long side of the strip-shaped battery sheet.

8. The photovoltaic module according to claim 1, characterized in that: The line width of the auxiliary grid line at one end connected to the front main grid is 0.5 mm to 3 mm, and the line width at one end away from the front main grid is 0.01 to 0.2 mm.

9. The photovoltaic module according to claim 1, characterized in that: A back welding pad is also provided on the back of the strip-shaped battery sheet. The back welding pad is perpendicular to the back main grid and is provided in the middle of the strip-shaped battery sheet.

10. The photovoltaic module according to claim 9, characterized in that: The line width of the back welding pad is 0.5 mm to 3 mm, and the line length is 3 mm to 30 mm.

11. The photovoltaic module according to claim 1, characterized in that: The length of the long side of the strip-shaped battery sheet is N times the length of the short side. In the plurality of battery strings, each N battery strings are connected in parallel via a bus bar, and N is an integer not less than 4.

12. A method for manufacturing a photovoltaic module according to any one of claims 1 to 11, comprising the following steps: S1: providing a silicon wafer, and setting a front main grid on one edge of the front side of the silicon wafer; S2: cutting a groove on the silicon wafer in a direction perpendicular to the front main grid, wherein the cutting groove extends from the edge of the silicon wafer where the front main grid is located to the edge of the silicon wafer on the other side parallel to it; S3: performing a splitting process on the silicon wafer, so that the silicon wafer is split along the cutting groove to obtain a plurality of strip-shaped battery cells, and the short side edges of the strip-shaped battery cells have the front main grid; S4: Overlapping and connecting the short edges of the strip-shaped battery sheets to form a battery series, and manufacturing a photovoltaic module.

13. The method for manufacturing a photovoltaic module according to claim 12, wherein: Before the chip splitting process, a conductive glue is pre-placed on the front or back side of the silicon wafer, and the conductive glue is distributed on one side edge of the silicon wafer in a direction parallel to the front main grid.

14. The method for manufacturing a photovoltaic module according to claim 13, wherein: The conductive glue is printed onto the front main grid on the front side of the silicon wafer by printing.

15. The method for manufacturing a photovoltaic module according to claim 12, wherein: After the cleaving process, conductive glue is applied to the short edges of each battery strip.

16. A method for manufacturing a photovoltaic module according to any one of claims 1 to 11, comprising the following steps: S1: providing a silicon wafer, wherein a front main grid and a plurality of secondary grid lines parallel to the front main grid are provided on the front side of the silicon wafer, and only one side edge of two oppositely disposed sides of the front side of the silicon wafer is provided with the front main grid; S2: The silicon wafer is equally split to obtain a plurality of strip-shaped cells, and the front main grid is equally divided into a plurality of segments and respectively arranged on the short side edge of each strip-shaped cell; S3: Connecting the strip-shaped solar cells in series to produce a photovoltaic module.

17. The method for manufacturing a photovoltaic module according to claim 16, wherein: The equal splitting processing includes: Use laser to carve several equally spaced cutting grooves on the silicon wafer in a direction perpendicular to the front main grid; External force is applied to the silicon wafer to cause the silicon wafer to split along the cutting grooves to form a plurality of strip-shaped battery cells.

18. The method for manufacturing a photovoltaic module according to claim 17, characterized in that: The cutting groove is formed on the back side of the battery cell.

19. The method for manufacturing a photovoltaic module according to claim 18, wherein: The back side of the silicon wafer is provided with a back main grid and a plurality of mutually parallel back welding pads, wherein the back main grid is arranged at the edge of the silicon wafer on the other side opposite to the edge of the silicon wafer where the front main grid is located; the laser uses the back welding pad to locate the center line position between two adjacent back welding pads, and carves a cutting groove at this position.

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