Back contact cells and photovoltaic modules

Abstract

The application is suitable for the photovoltaic technical field, and provides a back contact cell and a photovoltaic module, the back contact cell comprising: a silicon substrate and a plurality of auxiliary grids, the auxiliary grids comprising first auxiliary grids and second auxiliary grids with different polarities; the first auxiliary grids and the second auxiliary grids are arranged on the back surface of the silicon substrate, extend along a first direction and are alternately arranged at equal intervals along a second direction, the first direction is perpendicular to the second direction; a plurality of series connection areas are arranged on the back surface of the silicon substrate, the series connection areas are used for arranging solder strips; the series connection areas extend along the second direction and cross the plurality of auxiliary grids; the solder strips arranged in one series connection area are electrically connected with the auxiliary grids of one kind of polarity, the solder strips arranged in adjacent two series connection areas are electrically connected with the auxiliary grids of different polarities; a bonding pad is arranged at the connection position of the series connection area and the auxiliary grid of the corresponding polarity; and the length of the solder paste printed on the bonding pad is not more than the length of the bonding pad. The back contact cell and the photovoltaic module provided by the application can avoid the corrosion of the solder paste on the corresponding position of the grid line, and can improve the reliability of the module.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of photovoltaic, and particularly relates to a back contact cell and a photovoltaic module. BACKGROUND

[0002] In the related art, in the main grid-free back contact solar cell, a solder pad for distributing solder paste is arranged at a position where each sub-grid is connected with a solder strip. The existing solder pad is in a long strip shape, and the solder paste can be printed on the solder pad. The solder paste is crucial for ensuring the welding quality, and insufficient or excessive solder paste can cause insufficient welding point strength, so that the solar cell is prone to welding failure in the subsequent use process, affecting the reliability of the solar cell. SUMMARY

[0003] The present application provides a back contact cell and a photovoltaic module, aiming to solve the problem that improper control of the amount of solder paste can affect the reliability of the cell.

[0004] The present application provides a back contact cell, comprising:

[0005] a silicon substrate and a plurality of sub-grids, the sub-grids comprising first sub-grids and second sub-grids with different polarities;

[0006] The first sub-grids and the second sub-grids are arranged on the back surface of the silicon substrate, extend along a first direction and are alternately arranged at equal intervals along a second direction, and the first direction is perpendicular to the second direction;

[0007] The back surface of the silicon substrate is provided with a plurality of stringing areas for arranging solder strips; the stringing areas are arranged at intervals along the first direction and extend along the second direction, and cross the plurality of sub-grids; the solder strips arranged in one stringing area are electrically connected with the sub-grids of one polarity, and the solder strips arranged in adjacent two stringing areas are electrically connected with the sub-grids of different polarities;

[0008] The stringing area and the sub-grid of the corresponding polarity are provided with a solder pad at the connection position, the solder pad extends along the first direction, and the width of the solder pad is not more than the width of the stringing area; the solder pad is used for welding at least part of the area of the solder strip on the silicon substrate;

[0009] The amount of solder paste printed on the solder pad is not more than the corresponding area of the solder pad.

[0010] In some embodiments, the solder paste comprises at least two sections of solder paste, and there is a gap between the at least two sections of solder paste.

[0011] In some embodiments, the solder pad comprises at least two sections of solder pad, and there is a gap between the at least two sections of solder pad, and the number of sections of the solder pad is greater than or equal to the number of sections of the solder paste.

[0012] In some embodiments, when the number of segments of the solder pad is equal to the number of segments of the solder paste, the at least two segments of the solder paste are printed on the at least two segments of the solder pad one by one.

[0013] In some embodiments, when the number of segments of the solder pad is greater than the number of segments of the solder paste, the at least two segments of the solder paste are printed on the corresponding number of segments of the solder pad in sequence.

[0014] In some embodiments, the length of the solder pad in the first direction is greater than the length of the solder paste in the first direction by 2 mm.

[0015] In some embodiments, the solder pad is triangular, rectangular, trapezoidal, circular, or oval.

[0016] In some embodiments, the at least two segments of the solder pad are different in size.

[0017] In some embodiments, when the number of segments of the at least two segments of the solder pad is twice the number of segments of the at least two segments of the solder paste, the at least two segments of the solder paste are arranged at intervals on the at least two segments of the solder pad.

[0018] The present application also provides a back contact cell, comprising the back contact cell according to any one of the above.

[0019] The back contact cell and the photovoltaic module provided by the present application limit the printing area of the solder paste to the area corresponding to the solder pad, which can avoid the solder paste reacting with the sub-grid connected to the corresponding position of the solder pad, and thus corroding the sub-grid, thereby avoiding broken grids or false welding, and greatly improving the reliability of the solar cell. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a schematic diagram of the overall structure of the back contact cell provided by the embodiments of the present application;

[0021] Figure 2 is one of the schematic diagrams of the solder pad structure of the back contact cell provided by the embodiments of the present application;

[0022] Figure 3 is the third schematic diagram of the solder pad structure of the back contact cell provided by the embodiments of the present application;

[0023] Figure 4 is the fourth schematic diagram of the solder pad structure of the back contact cell provided by the embodiments of the present application;

[0024] Figure 5 is the fifth schematic diagram of the solder pad structure of the back contact cell provided by the embodiments of the present application;

[0025] Figure 6 is the sixth schematic diagram of the solder pad structure of the back contact cell provided by the embodiments of the present application;

[0026] Figure 7 Figure 7 is a schematic diagram of a back contact cell pad structure according to an embodiment of the application;

[0027] Figure 8 Figure 8 is a schematic diagram of a back contact cell pad structure according to an embodiment of the application;

[0028] Figure 9 Figure 9 is a schematic diagram of a back contact cell pad structure according to an embodiment of the application;

[0029] Figure 10 Figure 10 is a schematic diagram of a back contact cell pad structure according to an embodiment of the application;

[0030] Figure 11 Figure 11 is a schematic diagram of a back contact cell pad structure according to an embodiment of the application;

[0031] Figure 12 Figure 12 is a schematic diagram of a back contact cell pad structure according to an embodiment of the application;

[0032] Figure 13 Figure 13 is a schematic diagram of a photovoltaic module according to an embodiment of the application. DETAILED DESCRIPTION

[0033] In order to make the objectives, technical solutions, and advantages of the present application clearer, the present application will be described in further detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are intended to explain the present application only and are not intended to limit the present application.

[0034] Reference to "an embodiment" or "the embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. The appearances of the phrase "in one embodiment" or "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all directed to the same embodiment, or to a single alternative embodiment. It is explicitly contemplated that embodiments described herein can be combined.

[0035] In the description of the present application, it is to be understood by those skilled in the art that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features referred to. Therefore, the features defined as "first", "second" can be explicitly or implicitly included one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0036] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection or can communicate with each other; it can be directly connected, or indirectly connected through intermediate medium, it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0037] The back contact battery and photovoltaic module provided by the embodiments of the present application will be described in detail below in combination with specific examples and application scenarios. Figures 1 to 13

[0038] Figure 1 is one of the structural schematic diagrams of the back contact battery provided by the embodiments of the present application. As shown in Figure 1 The present application provides a back contact battery, comprising: a silicon substrate 10 and a plurality of auxiliary grids, the auxiliary grids comprising first auxiliary grids 20 and second auxiliary grids 30 with different polarities;

[0039] The first auxiliary grid 20 and the second auxiliary grid 30 are arranged on the back surface of the silicon substrate 10, extend along a first direction and are alternately arranged at equal intervals along a second direction, and the first direction is perpendicular to the second direction;

[0040] The back surface of the silicon substrate 10 is provided with a plurality of series connection areas 40, and the series connection areas 40 are used for arranging solder strips; the series connection areas 40 are arranged at intervals along the first direction and extend along the second direction, and cross the plurality of auxiliary grids; the solder strip arranged in one series connection area 40 is electrically connected with the auxiliary grid of one kind of polarity, and the solder strips arranged in the adjacent two series connection areas 40 are electrically connected with the auxiliary grids of different polarities;

[0041] ​The connection of the stringing area 40 and the sub-grid of the corresponding polarity is provided with a solder pad 50, the solder pad 50 extends along the first direction, the width of the solder pad 50 does not exceed the width of the stringing area 40; the solder pad 50 is used for welding at least a partial area of the solder strip on the silicon substrate 10;

[0042] As shown in the first direction, the length of the tin paste 60 printed on the solder pad 50 does not exceed the length of the solder pad 50. Figure 2

[0043] In the embodiment of the present application, the back contact battery is a main grid-free back contact battery. The main grid-free back contact battery can be a whole battery piece, or a half piece, a third piece or other proportion of battery piece divided from the whole battery piece. It should be noted that the drawings provided by the present application are schematic diagrams, and do not limit the specific form of the back contact battery.

[0044] Further, the silicon substrate 10 includes a front surface and a back surface, the front surface faces the sun and mainly receives direct sunlight, and the back surface faces the mounting surface of the photovoltaic module and mainly receives sunlight reflected by the mounting surface, for example, the ground, the roof and the like. Alternatively, the back surface of the silicon substrate 10 is the surface provided with the sub-grid. Moreover, the silicon substrate 10 is provided with a doped layer and a passivation layer arranged in a stack, and the doped layer can be connected with the sub-grid to establish an ohmic contact.

[0045] The back surface of the silicon substrate 10 is provided with a plurality of sub-grids, including first sub-grids 20 or second sub-grids 30 of different polarities, the plurality of first sub-grids 20 or second sub-grids 30 are arranged alternately and equidistantly along a second direction intersecting the first direction. The first direction can be the length direction of the sub-grid, i.e. the horizontal direction in Figure 1 and Figure 2 The second direction can be the width direction of the sub-grid, i.e. the vertical direction in Figure 1 and Figure 2 Of course, in other embodiments, the first direction and the second direction can also be other directions, for example, diagonal directions, etc., which are not limited here.

[0046] The plurality of sub-grids can be positive sub-grids or negative sub-grids, which are not limited here. For example, the first sub-grid 20 is a positive sub-grid, and the second sub-grid 30 is a negative sub-grid; the second sub-grid 30 is a positive sub-grid, and the first sub-grid 20 is a negative sub-grid.

[0047] As shown in the first direction, the length of the tin paste 60 printed on the solder pad 50 does not exceed the length of the solder pad 50. Figure 1 As shown, the back surface of the silicon substrate 10 also has a plurality of stringing areas 40, the plurality of stringing areas 40 include first stringing areas 401 and second stringing areas 402 for collecting currents of sub-grids of different polarities. The plurality of stringing areas 40 extend along the second direction and intersect all the first sub-grids 20 and the second sub-grids 30, and the first stringing areas 401 and the second stringing areas 402 are arranged alternately and parallelly along the first direction.​

[0048] It can be understood that each stringing area 40 collects the current on the sub-gate of a single polarity. Therefore, in the case of collecting the current of the first sub-gate 20 at the stringing area 40, the solder pad 50 is arranged at the intersection position of the stringing area 40 and the first sub-gate 20, and no solder pad 50 is arranged at the intersection position of the stringing area 40 and the second sub-gate 30.

[0049] In the case of collecting the current of the second sub-gate 30 at the stringing area 40, the solder pad 50 is arranged at the intersection position of the stringing area 40 and the second sub-gate 30, and no solder pad 50 is arranged at the intersection position of the stringing area 40 and the first sub-gate 20.

[0050] As shown in Figure 2 , the solder pad 50 is used to place the solder paste 60, and the solder paste 60 can form a good solder connection with the solder strip after melting. The solder pad 50 extends in the first direction, and the length of the solder pad 50 in the first direction is greater than the length of the solder paste 60 printed in the first direction. The width of the solder pad 50 in the second direction can be approximately equal to the width of the solder paste 60 in the second direction.

[0051] If the length of the solder paste 60 in the first direction exceeds the length of the solder pad 50 in the first direction, the area without the solder pad 50, and the solder paste 60 is corrosive, the solder paste 60 can react with the sub-gate in the area without the solder pad 50, causing the sub-gate to appear broken or false welding, thereby affecting the reliability of the battery.

[0052] It can be understood that the longer the length of the solder pad 50, the greater the soldering tension of the solder strip. The width of the solder pad 50 is determined based on the distance between the first sub-gate 20 and the second sub-gate 30 and the width of the first sub-gate 20 or the second sub-gate 30, for example, the width of the solder pad 50 can be equal to or slightly greater than the width of the first sub-gate 20 or the second sub-gate 30.

[0053] In the embodiment of the present application, referring to Figure 1 , the first stringing area 401 is used to collect the current of the first sub-gate 20; and the second stringing area 402 is used to collect the current of the second sub-gate 30. Therefore, the first stringing area 401 and the second stringing area 402 correspond to areas of different polarities.

[0054] In actual execution, the stringing area 40 can be used to fix the solder strip by placing the solder paste 60 on the solder pad 50. The width of the solder strip does not exceed the width of the stringing area 40. The solder strip extends along the second direction and intersects all sub-gates, and the solder strips of different polarities are arranged alternately in parallel along the first direction.

[0055] Taking the first sub-gate 20 as the positive sub-gate and the second sub-gate 30 as the negative sub-gate as an example, the first series connection area 401 that collects the current of the first sub-gate 20 can be provided with a positive solder strip, and the second series connection area 402 that collects the current of the second sub-gate 30 can be provided with a negative solder strip. Then the positive solder strip is electrically connected to the first sub-gate 20 and insulated from the second sub-gate 30, and the negative solder strip is electrically connected to the second sub-gate 30 and insulated from the first sub-gate 20.

[0056] In actual implementation, since the first sub-gate 20 and the second sub-gate 30 are alternately set, and the series area 40 collects the current of the sub-gate with a single polarity, the pads 50 set in the series area 40 are set at intervals of one sub-gate.

[0057] The back contact battery provided in this embodiment of the invention limits the length of the solder paste in the first direction to the length of the pad in the first direction. This can prevent the solder paste from reacting with the sub-gate connected to the corresponding position of the pad, thereby preventing corrosion of the sub-gate and avoiding grid breakage or poor soldering, thus greatly improving the reliability of the solar cell.

[0058] In some embodiments, solder paste 60 includes at least two sections of solder paste with a gap between them.

[0059] In actual implementation, the solder paste 60 can be a segmented structure, with the solder paste 60 divided into multiple segments on the printed paper pads 50, and there is a gap between two adjacent segments of solder paste 60. The length of each segment of solder paste 60 can be set according to actual needs, and no specific limit is made here.

[0060] like Figure 3 As shown, there are two sections of solder paste 60 on pad 50; Figure 4 As shown, there are three sections of solder paste 60 on pad 50; Figure 5 As shown, there are four sections of solder paste 60 on pad 50.

[0061] Understandably, if only one section of solder paste 60 is used, and that section is obstructed by foreign objects, the solder ribbon will be unable to make an electrical connection with the sub-gate. Therefore, using multiple sections of solder paste 60 can increase the probability of achieving a stable electrical connection between the solder ribbon and the sub-gate.

[0062] The back contact battery provided in this embodiment of the invention uses segmented solder paste, which not only saves solder paste but also achieves dispersed contact between the solder paste and the solder ribbon, thus improving soldering stability.

[0063] In some embodiments, the pad 50 includes at least two segments of the pad 50, with a gap between the at least two segments of the pad 50, and the number of segments of the pad 50 is greater than or equal to the number of segments of the solder paste 60.

[0064] In actual implementation, the soldering pad 50 can also adopt a segmented structure. It should be noted that when the soldering pad 50 adopts a segmented structure, the solder paste 60 must also adopt a segmented structure, that is, the solder paste 60 can only be printed on the segmented soldering pad 50 and cannot adopt a one-segment structure to cover all the soldering pads 50, therefore, the number of segments of the soldering pad 50 can be greater than or equal to the number of segments of the solder paste 60. For example, as shown in FIG. 16, the soldering pad 50 can be divided into four segments, and the solder paste 60 can be divided into two segments, three segments or four segments. Figure 6

[0065] It can be understood that the length of each segment of the soldering pad 50 in the first direction is also greater than the length of the solder paste printed on the segment of the soldering pad 50 in the first direction.

[0066] In some embodiments, when the number of segments of the soldering pad 50 is equal to the number of segments of the solder paste 60, at least two segments of the solder paste 60 are printed on at least two segments of the soldering pad 50 one by one.

[0067] In actual implementation, when the number of segments of the soldering pad 50 is equal to the number of segments of the solder paste 60, each segment of the soldering pad 50 can correspond to one segment of the solder paste 60. For example, as shown in FIG. 16, the soldering pad 50 can be divided into four segments, and the solder paste 60 can also be divided into four segments, that is, the four segments of the soldering pad 50 correspond to the four segments of the solder paste 60 one by one; as shown in FIG. 17, the soldering pad 50 can be divided into two segments, and the solder paste 60 can also be divided into two segments, that is, the two segments of the soldering pad 50 correspond to the two segments of the solder paste 60 one by one. Figure 6 Figure 7

[0068] In some embodiments, when the number of segments of the soldering pad 50 is greater than the number of segments of the solder paste 60, at least two segments of the solder paste 60 are printed on the corresponding number of segments of the soldering pad 50 in sequence.

[0069] In actual implementation, when the number of segments of the soldering pad 50 is greater than the number of segments of the solder paste 60, at least two segments of the solder paste 60 can be printed on any of the at least two segments of the soldering pad 50, which is not specifically limited herein. For example, as shown in FIG. 16, the soldering pad 50 can be divided into four segments, and the solder paste 60 can be divided into two segments, that is, the two segments of the solder paste 60 can be printed on the two segments of the soldering pad 50 in the middle of the four segments of the soldering pad 50. Figure 8

[0070] In some embodiments, the length of the soldering pad 50 in the first direction is greater than the length of the solder paste 60 in the first direction by 2 mm.

[0071] In actual implementation, the maximum length of the soldering pad 50 can be 2 mm to 3 mm, and the maximum length of the solder paste 60 can be 1.8 mm to 2.8 mm.

[0072] ​​​​The maximum length of the pad 50 refers to the length between two opposite edges of the pad 50 in the first direction, and the maximum length of the solder paste 60 refers to the length between two opposite edges of the solder paste 60 in the first direction.

[0073] In some embodiments, the pad 50 is triangular, rectangular, trapezoidal, circular, or elliptical.

[0074] like Figures 1 to 8 As shown, pad 50 can be rectangular. Of course, in other embodiments, the shape of pad 50 can be set according to requirements, such as... Figure 9 As shown, pad 50 can also be trapezoidal; or it can be triangular or circular, or as shown in the figure. Figure 10 As shown, it can be elliptical or similar, and no specific limitation is made here.

[0075] In some embodiments, at least two pads 50 are of different sizes.

[0076] It is understandable that the size of pad 50 refers to its length in the first direction, and pad 50 can be segmented into equal or unequal sections. For example... Figure 11 As shown, pad 50 can be divided into two segments of unequal length.

[0077] In some embodiments, where the number of segments of at least two pads 50 is twice the number of segments of at least two solder pastes 60, at least two solder pastes 60 are spaced apart on at least two pads 50.

[0078] In practice, when the number of segments on pad 50 is greater than the number of segments on solder paste 60, at least two segments of solder paste 60 can be spaced apart across multiple pad segments 50. When the number of segments on pad 50 is exactly twice the number of segments on pad 50, a segment of solder paste 60 can be placed every other pad segment 50, resulting in a more uniform distribution of the solder paste 60 and promoting stable soldering. Figure 12 As shown, the number of segments of pad 50 is 4 and the number of segments of solder paste 60 is 2, so the 2 segments of solder paste 60 can be set on the 4 segments of pad 50 at intervals.

[0079] Figure 13 This is a schematic diagram of the structure of a photovoltaic module provided in an embodiment of the present invention. Figure 13 As shown, the present invention also provides a photovoltaic module 100, including the back contact cell 101 in any of the above embodiments.

[0080] The back contact battery 101 has been described in detail in the above embodiments, and will not be repeated here.

[0081] The photovoltaic module provided by the embodiment of the present application limits the printing area of the tin paste to the area corresponding to the solder pad, can avoid the reaction of the tin paste with the sub-grid connected at the position corresponding to the solder pad, and further corrodes the sub-grid, so as to avoid the occurrence of broken grid or false welding, and greatly improves the reliability of the photovoltaic module.

[0082] It can be understood that those skilled in the art can combine various embodiments in various embodiments in the above embodiments to obtain various embodiments of the technical solutions.

[0083] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A back contact cell, characterized in that, The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell.

2. The back contact cell of claim 1, wherein, The application relates to a back contact cell.

3. The back contact cell of claim 2, wherein, The application relates to a back contact cell.

4. The back contact cell of claim 2, wherein, The application relates to a back contact cell.

5. The back contact cell of claim 1, wherein, The application relates to a back contact cell.

6. The back contact cell according to any of claims 1-5, wherein, The application relates to a back contact cell.

7. The back contact cell of claim 1, wherein, The application relates to a back contact cell.

8. The back contact cell of claim 4, wherein, The application relates to a back contact cell.

9. A photovoltaic module, characterized by The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. 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The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a back contact cell. The application relates to a

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