Back contact battery and photovoltaic module

Abstract

The invention is applicable to the field of photovoltaic technology, and provides a back contact battery and a photovoltaic module, the back contact battery comprises a silicon substrate and a plurality of auxiliary grids, and the auxiliary grids comprise first auxiliary grids and second auxiliary grids with different polarities; the first auxiliary grids and the second auxiliary grids are arranged on the back face of the silicon substrate, extend in the first direction and are alternately arranged at equal intervals in the second direction, and 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 and are used for arranging welding strips; the serial connection region extends along the second direction and is crossed with the plurality of secondary grids; the welding strip arranged in one series connection area is electrically connected with the auxiliary grid with one polarity, and the polarities of the auxiliary grids connected with the welding strips arranged in two adjacent series connection areas are different; a bonding pad is arranged at the joint of the serial connection region and the auxiliary grid with the corresponding polarity; the length of the solder paste printed on the bonding pad does not exceed the length of the bonding pad. According to the back contact battery and the photovoltaic module provided by the invention, the solder paste is prevented from corroding the grid line at the corresponding position of the bonding pad, and the reliability of the module can be improved.

Description

Technical Field

[0001] The present invention belongs to the field of photovoltaic technology, and in particular relates to a back contact cell and a photovoltaic module. Background Art

[0002] In the related art, in a main grid-free back contact solar cell, a pad for distributing solder paste is provided at the position where each secondary grid is connected to the solder ribbon. The existing solder pad is in the shape of a long strip, and the solder paste can be printed on the solder pad. The solder paste is crucial to ensure the quality of welding. Insufficient or excessive solder paste may lead to insufficient strength of the welding point, making the solar cell prone to welding failure during subsequent use, affecting the reliability of the solar cell. Summary of the invention

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

[0004] The present invention provides a back contact battery, comprising:

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

[0006] The first auxiliary gate and the second auxiliary gate are arranged on the back side of the silicon substrate, extending along a first direction and alternately arranged at equal intervals along a second direction, and the first direction is perpendicular to the second direction;

[0007] The back side of the silicon substrate is provided with a plurality of series connection areas, and the series connection areas are used to set welding strips; the series connection areas are arranged at intervals along the first direction, and extend along the second direction, and intersect with the plurality of auxiliary grids; the welding strip arranged in one series connection area is electrically connected to an auxiliary grid of one polarity, and the auxiliary grids electrically connected to the welding strips arranged in two adjacent series connection areas have different polarities;

[0008] A pad is provided at the connection between the series connection area and the auxiliary grid of the corresponding polarity, the pad extends along the first direction, and the width of the pad does not exceed the width of the series connection area; the pad is used to weld at least a part of the welding strip to the silicon substrate;

[0009] The solder paste printed on the pad does not exceed the area corresponding to the pad.

[0010] In some embodiments, the solder paste includes 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 pad includes at least two sections of the pad, there is a gap between the at least two sections of the pad, and the number of sections of the 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 solder paste are printed on the at least two segments of the solder pad in a one-to-one correspondence.

[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 solder paste are printed sequentially on the solder pads with corresponding numbers of segments.

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

[0015] In some embodiments, the pad is triangular, rectangular, trapezoidal, circular or elliptical in shape.

[0016] In some embodiments, the at least two sections of the pads have different sizes.

[0017] In some embodiments, when the number of segments of the at least two sections of the solder pads is twice the number of segments of the at least two sections of the solder paste, the at least two sections of the solder paste are spaced apart on the at least two sections of the solder pads.

[0018] The present invention also provides a photovoltaic module, comprising: a back contact cell as described in any one of the above items.

[0019] The back contact cell and photovoltaic module provided by the present invention limit the printing area of ​​the solder paste to the area corresponding to the pad, which can prevent the solder paste from reacting with the secondary grid connected to the corresponding position of the pad and then corroding the secondary grid, thereby avoiding broken grid or cold solder joints, and greatly improving the reliability of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of the overall structure of a back contact battery provided by an embodiment of the present invention;

[0021] Figure 2 This is one of the schematic diagrams of the pad structure of the back contact battery provided by an embodiment of the present invention;

[0022] Figure 3 This is the third schematic diagram of the pad structure of the back contact battery provided by the embodiment of the present invention;

[0023] Figure 4 This is the fourth schematic diagram of the pad structure of the back contact battery provided by the embodiment of the present invention;

[0024] Figure 5 This is the fifth schematic diagram of the pad structure of the back contact battery provided by the embodiment of the present invention;

[0025] Figure 6 This is the sixth schematic diagram of the pad structure of the back contact battery provided by the embodiment of the present invention;

[0026] Figure 7 This is the seventh schematic diagram of the pad structure of the back contact battery provided by the embodiment of the present invention;

[0027] Figure 8 This is the eighth schematic diagram of the pad structure of the back contact battery provided by the embodiment of the present invention;

[0028] Fig. 9 This is the ninth schematic diagram of the pad structure of the back contact battery provided by the embodiment of the present invention;

[0029] Fig.10 This is the tenth schematic diagram of the pad structure of the back contact battery provided by the embodiment of the present invention;

[0030] Fig.11 This is the eleventh schematic diagram of the pad structure of the back contact battery provided by the embodiment of the present invention;

[0031] Fig.12 This is the twelfth schematic diagram of the pad structure of the back contact battery provided in an embodiment of the present invention;

[0032] Fig.13 It is a schematic diagram of the structure of a photovoltaic module provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] Reference to "embodiments" or "implementations" in the present invention means that the specific features, components, or characteristics described in conjunction with the embodiments or implementations may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0035] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0036] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] Combine the following Figures 1 to 13 , the back contact cell and photovoltaic module provided by the embodiments of the present invention are described in detail through specific embodiments and their application scenarios.

[0038] Figure 1 FIG. 1 is one of the structural schematic diagrams of the back contact battery provided by the embodiment of the present invention. Figure 1 As shown, the present invention provides a back contact battery, comprising: a silicon substrate 10 and a plurality of sub-grids, wherein the sub-grids include a first sub-grid 20 and a second sub-grid 30 with different polarities;

[0039] The first sub-gate 20 and the second sub-gate 30 are disposed on the back side of the silicon substrate 10, extending along a first direction and alternately arranged at equal intervals along a second direction, wherein the first direction is perpendicular to the second direction;

[0040] A plurality of series connection areas 40 are provided on the back of the silicon substrate 10, and the series connection areas 40 are used to set welding strips; the series connection areas 40 are arranged at intervals along the first direction, and extend along the second direction, crossing with a plurality of sub-grids; a welding strip arranged in one series connection area 40 is electrically connected to a sub-grid of one polarity, and the welding strips arranged in two adjacent series connection areas 40 are electrically connected to sub-grids of different polarities;

[0041] A pad 50 is provided at the connection between the series connection area 40 and the secondary grid of the corresponding polarity. The pad 50 extends along the first direction. The width of the pad 50 does not exceed the width of the series connection area 40. The pad 50 is used to weld at least a part of the welding strip to the silicon substrate 10.

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

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

[0044] Furthermore, the silicon substrate 10 includes a front side and a back side, the front side faces the sun and mainly receives direct sunlight, and the back side faces the mounting surface of the photovoltaic module and mainly receives sunlight reflected by the mounting surface, such as the ground, the roof, etc. In other words, the back side of the silicon substrate 10 is the side provided with the auxiliary grid. In addition, the silicon substrate 10 is provided with a doping layer and a passivation layer arranged in a stacked manner, and the doping layer can be connected to the auxiliary grid to establish an ohmic contact.

[0045] A plurality of sub-grids are arranged on the back of the silicon substrate 10, including first sub-grids 20 or second sub-grids 30 with different polarities, and the plurality of first sub-grids 20 or second sub-grids 30 are all extended along a first direction and arranged alternately and equidistantly along a second direction, and the second direction intersects the first direction. The first direction may be the length direction of the sub-grid, i.e. Figure 1 and Figure 2 The second direction may be specifically the width direction of the secondary grid, that is, Figure 1 and Figure 2 Of course, in other embodiments, the first direction and the second direction may also be other directions, such as diagonal directions, etc., which are not specifically limited here.

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

[0047] like Figure 1 As shown, there are a plurality of series connection regions 40 on the back side of the silicon substrate 10, and the plurality of series connection regions 40 include a first series connection region 401 and a second series connection region 402 for collecting currents of sub-gates of different polarities. The plurality of series connection regions 40 extend along the second direction and intersect with all the first sub-gates 20 and the second sub-gates 30, and the first series connection regions 401 and the second series connection regions 402 are alternately arranged in parallel along the first direction.

[0048] It is understandable that each series connection area 40 collects the current on the sub-gate of a single polarity. Therefore, when the series connection area 40 collects the current of the first sub-gate 20, a pad 50 is provided at the intersection of the series connection area 40 and the first sub-gate 20, and no pad 50 is provided at the intersection of the series connection area 40 and the second sub-gate 30.

[0049] When the series connection region 40 collects the current of the second sub-gate 30 , a pad 50 is disposed at the intersection of the series connection region 40 and the second sub-gate 30 , and no pad 50 is disposed at the intersection of the series connection region 40 and the first sub-gate 20 .

[0050] like Figure 2 As shown, solder paste 60 is placed on the pad 50, and solder paste 60 can form a good solder connection with the solder strip after melting. The pad 50 extends along a first direction, and the length of the 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 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 pad 50 in the first direction, and the pad 50 is not set in the exceeding area, the solder paste 60 is corrosive and the solder paste 60 may react with the sub-grid in the area where the pad 50 is not set, causing the sub-grid to break or produce cold solder joints, thereby affecting the reliability of the battery.

[0052] It is understandable that the longer the length of the pad 50 is, the greater the welding tension on the welding strip is. The width of the pad 50 is determined based on the spacing between the first auxiliary grid 20 and the second auxiliary grid 30 and the width of the first auxiliary grid 20 or the second auxiliary grid 30. For example, the width of the pad 50 can be equal to or slightly larger than the width of the first auxiliary grid 20 or the second auxiliary grid 30.

[0053] In the embodiment of the present invention, refer to Figure 1 The first series region 401 is used to collect the current of the first sub-gate 20; the second series region 402 is used to collect the current of the second sub-gate 30. Therefore, the first series region 401 and the second series region 402 correspond to regions with different polarities.

[0054] In actual implementation, the series connection area 40 can be used to fix the solder strip by placing solder paste 60 on the pad 50. The width of the solder strip does not exceed the width of the series connection area 40. The solder strips extend along the second direction and cross all the auxiliary grids, and the solder strips of different polarities are alternately arranged in parallel along the first direction.

[0055] Taking the first sub-grid 20 as the positive sub-grid and the second sub-grid 30 as the negative sub-grid as an example, the first series area 401 for collecting the current of the first sub-grid 20 can be provided with a positive electrode welding strip, and the second series area 402 for collecting the current of the second sub-grid 30 can be provided with a negative electrode welding strip. The positive electrode welding strip is electrically connected to the first sub-grid 20 and insulated from the second sub-grid 30, and the negative electrode welding strip is electrically connected to the second sub-grid 30 and insulated from the first sub-grid 20.

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

[0057] The back-contact battery provided in an embodiment of the present invention limits the length of the solder paste in the first direction to the length of the pad in the first direction, which can prevent the solder paste from reacting with the secondary grid connected to the corresponding position of the pad and then corroding the secondary grid, thereby avoiding broken grid or cold solder joints, and greatly improving the reliability of the solar cell.

[0058] In some embodiments, the solder paste 60 includes at least two sections of solder paste, and there is a gap between the at least two sections of solder paste.

[0059] In actual implementation, the solder paste 60 can be a segmented structure, the solder paste 60 is divided into multiple sections on the printed paper pad 50, and there is a gap between two adjacent sections of solder paste 60. The length of each section of solder paste 60 can be set according to actual needs and is not specifically limited here.

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

[0061] It is understandable that if only one section of solder paste 60 is used, when the section of solder paste 60 is blocked by foreign matter, the solder strip cannot be electrically connected to the auxiliary grid. Therefore, multiple sections of solder paste 60 can increase the probability of achieving stable electrical connection between the solder strip and the auxiliary grid.

[0062] The back contact battery provided by the embodiment of the present invention adopts segmented solder paste, which can not only save solder paste, but also achieve dispersed contact between the solder paste and the solder strip, thereby improving welding stability.

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

[0064] In actual implementation, the pad 50 may also adopt a segmented structure. It should be noted that if the 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 pad 50, and cannot adopt a one-segment structure to cover all the pads 50. Therefore, the number of segments of the pad 50 can be greater than or equal to the number of segments of the solder paste 60. For example: Figure 6 As shown, the pad 50 can be divided into 4 sections, and the solder paste 60 can be divided into 2 sections, 3 sections or 4 sections.

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

[0066] In some embodiments, when the number of segments of the solder 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 the at least two segments of the solder pad 50 in a one-to-one correspondence.

[0067] In actual implementation, if the number of segments of the pad 50 is equal to the number of segments of the solder paste 60, each segment of the pad 50 can be printed with a corresponding segment of the solder paste 60. Figure 6 As shown, the pad 50 can be divided into 4 sections, and the solder paste 60 can also be divided into 4 sections, and the 4 sections of the pad 50 correspond to the 4 sections of the solder paste 60 one by one; Figure 7 As shown, the pad 50 can be divided into two sections, and the solder paste 60 can also be divided into two sections, and the two sections of the pad 50 correspond to the two sections of the solder paste 60 one by one.

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

[0069] In actual implementation, if the number of segments of the 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 number of the pads 50 in the at least two segments, and no specific limitation is made here. Figure 8 As shown, the solder pad 50 can be divided into 4 sections, and the solder paste 60 can be divided into 2 sections, and then the 2 sections of solder paste 60 can be printed on the 2 sections of solder pads 50 in the middle of the 4 sections of solder pads 50 .

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

[0071] In actual implementation, the maximum length of the pad 50 may be 2 mm to 3 mm, and the maximum length of the solder paste 60 may 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 in shape.

[0074] like Figure 1-Figure 8 As shown, the pad 50 may be rectangular. Of course, in other embodiments, the shape of the pad 50 may be set as required, such as Fig. 9 As shown, the pad 50 may also be a trapezoid; or may be a triangle or a circle, or as shown in FIG. Fig.10 As shown, it can be an elliptical shape, which is not specifically limited here.

[0075] In some embodiments, at least two sections of the pad 50 have different sizes.

[0076] It can be understood that the size of the pad 50 refers to the length in the first direction, and the pad 50 can be divided into sections in an equal or unequal manner. Fig.11 As shown, the pad 50 can be divided into two sections of unequal lengths.

[0077] In some embodiments, when the number of segments of the at least two segments of the solder pad 50 is twice the number of segments of the at least two segments of the solder paste 60 , the at least two segments of the solder paste 60 are disposed at intervals on the at least two segments of the solder pad 50 .

[0078] In actual implementation, when the number of segments of the 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 arranged at intervals in the multi-segment pad 50. When the number of segments of the pad 50 is exactly twice the number of segments of the pad 50, a segment of solder paste 60 can be arranged every interval of a pad 50, so that the distribution of the solder paste 60 is more uniform, which is conducive to achieving stable welding. Fig.12 As shown, the number of segments of the solder pad 50 is 4, and the number of segments of the solder paste 60 is 2, so two segments of the solder paste 60 can be arranged on the four segments of the solder pad 50 at intervals.

[0079] Fig.13 Schematic diagram of the structure of the photovoltaic module provided by the embodiment of the present invention. Fig.13 As shown, the present invention further provides a photovoltaic module 100, comprising the back contact cell 101 in any of the above embodiments.

[0080] The back contact cell 101 has been described in detail in the above embodiment and will not be described again here.

[0081] The photovoltaic module provided by the embodiment of the present invention limits the printing area of ​​the solder paste to the area corresponding to the pad, which can prevent the solder paste from reacting with the auxiliary grid connected to the corresponding position of the pad and then corroding the auxiliary grid, thereby avoiding broken grid or cold solder joints, and greatly improving the reliability of the photovoltaic module.

[0082] It is understandable that those skilled in the art can, under the guidance of the above embodiments, combine various implementation methods in the above embodiments to obtain technical solutions of multiple implementation methods.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A back contact battery, characterized in that: include: A silicon substrate and a plurality of sub-grids, wherein the sub-grids include a first sub-grid and a second sub-grid with different polarities; The first auxiliary gate and the second auxiliary gate are arranged on the back side of the silicon substrate, extending along a first direction and alternately arranged at equal intervals along a second direction, and the first direction is perpendicular to the second direction; The back side of the silicon substrate is provided with a plurality of series connection areas, and the series connection areas are used to set welding strips; the series connection areas are arranged at intervals along the first direction, and extend along the second direction, and intersect with the plurality of auxiliary grids; the welding strip arranged in one series connection area is electrically connected to an auxiliary grid of one polarity, and the auxiliary grids electrically connected to the welding strips arranged in two adjacent series connection areas have different polarities; A pad is provided at the connection between the series connection area and the auxiliary grid of the corresponding polarity, the pad extends along the first direction, and the width of the pad does not exceed the width of the series connection area; the pad is used to weld at least a part of the welding strip to the silicon substrate; In the first direction, the length of the solder paste printed on the pad does not exceed the length of the pad.

2. The back contact cell according to claim 1, characterized in that: The solder paste includes at least two sections of solder paste, and there is a gap between the at least two sections of solder paste.

3. The back contact battery according to claim 2, characterized in that: The pad includes at least two sections of the pad, there is a gap between the at least two sections of the pad, and the number of sections of the pad is greater than or equal to the number of sections of the solder paste.

4. The back contact cell according to claim 3, characterized in that: In a case where 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 solder paste are printed on the at least two segments of the solder pad in a one-to-one correspondence.

5. The back contact battery according to claim 3, characterized in that: In the case that 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 sequentially on the solder pads with corresponding numbers of segments.

6. The back contact cell according to claim 1, characterized in that: The length of the pad in the first direction is 2 mm greater than the length of the solder paste in the first direction.

7. The back contact cell according to any one of claims 1 to 6, characterized in that: The pad is in the shape of a triangle, a rectangle, a trapezoid, a circle or an ellipse.

8. The back contact battery according to claim 2, characterized in that: The at least two sections of pads have different sizes.

9. The back contact cell according to claim 5, characterized in that: In a case where the number of segments of the at least two sections of the solder pads is twice the number of segments of the at least two sections of the solder paste, the at least two sections of the solder paste are spaced apart on the at least two sections of the solder pads.

10. A photovoltaic module, characterized in that: include: A back contact battery according to any one of claims 1 to 9.

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