Back contact battery and photovoltaic module

Abstract

The invention discloses a back contact battery and a photovoltaic module, and relates to the field of photovoltaic technology. The back contact battery comprises a battery body which comprises a first surface and a second surface which are oppositely arranged, and the first surface is provided with a first edge and a second edge which are oppositely arranged along a first direction; the first fine grids and the second fine grids are arranged on the first surface, extend in the first direction and are alternately distributed in the second direction, the first direction intersects with the second direction, and the first fine grids and the second fine grids are different in grid polarity; the first bent connecting line is arranged on the first surface and extends in a wave shape in the second direction, the first end portion of the first bent connecting line is electrically connected with the end portion area, close to the first edge, of the first fine grid, and the first bent connecting line and the first fine grid are of an integrated structure. When the magnitude of current collected by the doped semiconductor layer is large, the first bent connecting line plays a role in current shunting, so that the transmission efficiency of current can be improved, and the photoelectric conversion efficiency of the back contact cell is further improved.

Description

Technical Field

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

[0002] A back-contact cell refers to a solar cell in which the light-facing side of the cell has no electrode, and the positive and negative electrodes are arranged on the backlight side of the cell. This can reduce the shading of the electrode to the cell, increase the short-circuit current of the cell, and improve the energy conversion efficiency of the cell.

[0003] However, due to process requirements, the large pads near the corners of the back-contact battery define a larger area of ​​the same polarity, which interrupts some of the opposite-polarity fine grids. Here, the horizontal like-polarity fine grids need to be connected by vertical connecting wires for convergence. When the connecting wires overlap with the like-polarity fine grids, they need to extend the longitudinal distance of the like-polarity fine grids, which creates the risk of short circuit. Summary of the invention

[0004] The purpose of the present application is to provide a back-contact cell and a photovoltaic module to improve the connection reliability between the horizontal isotropic fine grid and the vertical connecting line and the photoelectric conversion efficiency of the back-contact cell.

[0005] In order to achieve the above objectives, this application provides the following technical solutions:

[0006] A back contact battery, comprising:

[0007] The battery body comprises a first surface and a second surface arranged opposite to each other, wherein the first surface has a first side and a second side arranged opposite to each other along a first direction;

[0008] A plurality of first fine grids and a plurality of second fine grids are arranged on the first surface, and extend along the first direction and are alternately distributed along the second direction, the first direction intersects the second direction, and the first fine grids and the second fine grids have different properties;

[0009] The first curved connecting line is disposed on the first surface and extends in a wavy shape along the second direction. The first end of the first curved connecting line is electrically connected to the end region of the first fine grid close to the first edge, and the first curved connecting line and the first fine grid are an integral structure.

[0010] By adopting the above technical solution, the current collected by the first fine grid in the larger area of ​​the doped semiconductor layer is transmitted to the first curved connecting line, and then transmitted to other components through the first curved connecting line. When the amount of current collected by the doped semiconductor layer is large, the first curved connecting line plays the role of current shunting, which can improve the current transmission efficiency and thus improve the photoelectric conversion efficiency of the back contact battery. In addition, the first curved connecting line extends along the second direction, which is roughly perpendicular to the extension direction of the first fine grid. If the connecting line extends along a straight line, it is easy to cause breakage during the manufacturing process, affecting the current transmission; based on this, the first curved connecting line in the present application is wavy, and during the manufacturing process, the first curved connecting line is smoother as a whole and has a higher quality; for example, when the first curved connecting line is screen-printed, the wavy first curved connecting line can bypass the grid intersection, thereby improving the yield of the first curved connecting line.

[0011] In one implementation, the back contact cell further includes a first pad disposed on the first surface and proximate to the first edge;

[0012] The second end of the first curved connecting line is electrically connected to the first pad. In this way, the current collected by the first fine grid can be transmitted to the first pad through the first curved connecting line, and then transmitted to the outside of the back contact battery.

[0013] In one implementation, the second end of the first curved connecting wire is overlapped on the side of the first pad away from the battery body. In this way, after lamination, the second end of the first curved connecting wire is directly pressed on the first pad, which can prevent the second end of the first curved connecting wire from separating from the first pad, thereby improving the stability of the electrical contact between the second end of the first curved connecting wire and the first pad.

[0014] In one implementation, the first pad has a protrusion protruding toward one side of the first curved connecting line, and the second end of the first curved connecting line is electrically connected to the protrusion. With this technical solution, during the manufacturing process, the second end of the first curved connecting line can be directly formed on the side of the protrusion away from the battery body, which is conducive to the processing and positioning of the first curved connecting line.

[0015] In one implementation, at least one first fine grid is provided between the first end and the second end of the first curved connecting line, and the first fine grid between the first end and the second end of the first curved connecting line is electrically connected to the middle of the first curved connecting line. With this technical solution, the current collected by the plurality of first fine grids can be transmitted to the first pad through the first curved connecting line, further improving the current transmission efficiency.

[0016] In one implementation, an edge bus grid extending along the second direction between the first pad and the first edge is further included, and the edge bus grid is connected to the first pad via at least one second curved connection line extending along the first direction, so as to transmit the current collected by the plurality of first fine grids to the first pad by the edge bus grid. Since the edge bus grid needs to collect the current of the plurality of first fine grids, the width of the edge bus grid can be set wider to improve the current transmission efficiency.

[0017] In one implementation, the first end of the second curved connection line is overlapped on the side of the edge busbar away from the battery body; and / or the second end of the second curved connection line is overlapped on the side of the first pad away from the battery body. After lamination, the electrical contact stability of the two ends of the second curved connection line is better.

[0018] In one implementation, the width of the first curved connecting line is greater than the width of the second curved connecting line to ensure normal transmission of current, while adapting the width of the curved connecting line to its internal current to avoid waste of raw materials, and also allowing the first curved connecting line to be more reliably joined to the first fine gate; and / or, the width of the first curved connecting line is W1, 30μm≤W1≤70μm; using this technical solution, the width of the first curved connecting line is W1 set within a reasonable range, which can prevent the first curved connecting line from being too narrow to affect the current transmission efficiency, and prevent the first curved connecting line from being too wide to avoid waste of raw materials.

[0019] And / or, the width of the second curved connection line is W2, 20μm≤W2≤50μm. Setting the width of the second curved connection line W2 within a reasonable range can prevent the second curved connection line from being too narrow to affect current transmission efficiency, and prevent the second curved connection line from being too wide to avoid waste of raw materials.

[0020] In one implementation, the second curved connection line extends in a wave shape;

[0021] The wavelength of the first curved connecting line is L1, and the wavelength of the second curved connecting line is L2, │L1-L2│≤5μm; in this way, the wavelength L1 of the first curved connecting line is nearly equal to the wavelength L2 of the second curved connecting line, thereby ensuring that the current flowing through the first curved connecting line and the second curved connecting line is more uniform and preventing excessive concentration of local current. And / or, 200μm≤L1≤300μm; and / or, 200μm≤L2≤300μm. While ensuring the normal transmission of current, the current transmission path of the first curved connecting line and the second curved connecting line is prevented from being too long, thereby reducing the current transmission resistance.

[0022] In one implementation, there are multiple first curved connecting lines;

[0023] Along the first direction, the crests of the plurality of first curved connecting wires are aligned and the troughs of the plurality of first curved connecting wires are aligned. This arrangement makes the current on the upper side and the lower side of the first pad more uniform, preventing the current from being excessively concentrated locally.

[0024] In one implementation, at least one second fine gate has a bending section at its end near the first edge, and the bending section is at least partially located between the first curved connecting line and the first edge. With this arrangement, the bending section of the second fine gate and the first fine gate are simultaneously used to derive the current in the area between the first edge and the first curved connecting line, which can not only alleviate the problem of excessive concentration of current collection, but also help to reduce the current difference of doped semiconductor layers with opposite polarities.

[0025] The bending section includes a third connecting line and at least one sub-fine grid, the third connecting line extends along the second direction, the sub-fine grid extends along the first direction and one end thereof is electrically connected to the third connecting line.

[0026] In one implementation, the third connection line extends in a wavy shape. During the manufacturing process, the third connection line is smoother as a whole and has a higher quality. For example, when the third connection line is screen-printed, the wavy third connection line can bypass the grid intersection, thereby improving the yield of the third connection line.

[0027] A photovoltaic module comprises a back contact cell as described above and an electrical connector, wherein the electrical connector is electrically connected to a plurality of first fine grids. Compared with the prior art, the beneficial effects of the photovoltaic module provided by the embodiment of the present application are the same as those of the solar cell described above, and will not be elaborated here.

[0028] In one implementation, the end of the electrical connector overlaps at least a portion of the first curved connection line, so as to increase the contact area between the electrical connector and the first pad and the first curved connection line, thereby reducing contact resistance and improving current transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0030] Figure 1 A top view of a back contact battery provided in an embodiment of the present application;

[0031] Figure 2 A partial cross-sectional view of a back-contact battery provided by an embodiment of the present application along a direction parallel to the first surface;

[0032] Figure 3 for Figure 2 A partial enlarged view of the area in the middle dashed box;

[0033] Figure 4 A partial cross-sectional view of a back-contact battery provided in another embodiment of the present application along a direction parallel to the first surface;

[0034] Figure 5 A partial cross-sectional view of a back-contact battery provided in another embodiment of the present application along a direction parallel to the first surface;

[0035] Figure 6 A partial cross-sectional view of a back-contact battery provided in another embodiment of the present application along a direction parallel to the first surface;

[0036] Figure 7 A schematic diagram of a first curved connecting line provided in an embodiment of the present application;

[0037] Figure 8 A schematic diagram of a second curved connecting line provided in an embodiment of the present application;

[0038] Fig. 9 Another partial cross-sectional view of the back-contact battery provided in an embodiment of the present application along a direction parallel to the first surface.

[0039] Reference numerals:

[0040] 1-second fine grid, 2-first fine grid, 3-edge bus grid, 4-first side, 5-first curved connecting line, 6-first pad, 61-raised portion, 7-second side, 8-first doped semiconductor layer, 9-second doped semiconductor layer, 10-isolation region, 11-second curved connecting line, 12-bending section, 121-third connecting line, 13-second pad. DETAILED DESCRIPTION

[0041] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application 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 application and are not used to limit the present application.

[0042] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0043] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "multiple" means two or more, unless otherwise clearly and specifically defined. "Several" means one or more, unless otherwise clearly and specifically defined.

[0044] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", etc., indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0045] In the description of this application, 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 or an electrical connection; 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 this application can be understood according to specific circumstances.

[0046] In the back contact battery structure, generally multiple fine grids are electrically connected to the busbar through a larger pad to conduct current. The area of ​​the doped semiconductor layer with the same polarity as the pad around the larger pad is also larger (the width of the doped semiconductor layer around the pad is about 2.5 to 5 times the width of the doped semiconductor layer at other positions), and the amount of current collected by the doped semiconductor layer in this area is also large. Therefore, how to ensure the current transmission efficiency in the above area has become an urgent problem to be solved.

[0047] In order to improve the current transmission efficiency around the larger pad, the present application provides a back contact battery, see Figure 1 The back contact battery includes a battery body, a plurality of first fine grids 2, a plurality of second fine grids 1, and at least one first curved connecting line 5. In some embodiments, the back contact battery is a busbarless back contact battery, in which there is no busbar connection between the pads, and a portion of the terminal wire can be retained at the end to collect the current of the edge fine grid. In other embodiments, the back contact battery can be a busbar back contact battery, in which the busbar connects each column of pads.

[0048] The battery body includes a first surface and a second surface that are arranged opposite to each other, that is, the two surfaces that are opposite to each other along the thickness direction of the battery body are the first surface and the second surface respectively. The first surface has a first edge 4 and a second edge 7 that are opposite to each other along a first direction, that is, the first edge 4 and the second edge 7 are arranged along the first direction, and the first edge 4 and the second edge 7 both intersect with the first direction. For example, Figure 1 The left side is the first side 4, and the right side is the second side 7. In addition, the first surface may correspond to the backlight surface, and the second surface may correspond to the light-facing surface; or the first surface may correspond to the light-facing surface, and the second surface may correspond to the backlight surface. In this application, the backlight surface corresponding to the first surface is used as an example for explanation.

[0049] The first fine grid 2 and the second fine grid 1 both extend along the first direction, that is, the lengths of the first fine grid 2 and the second fine grid 1 are arranged along the first direction. In addition, a plurality of first fine grids 2 and a plurality of second fine grids 1 are alternately distributed along the second direction. The first fine grid 2 and the second fine grid 1 have different polarities, so that the first fine grid 2 and the second fine grid 1 can be used to derive the current collected by the battery body.

[0050] The second direction intersects the first direction, that is, the first direction is different from the second direction, and the angle between the first direction and the second direction can be an acute angle or a right angle. When the first direction is the length direction of the battery body, the second direction is the width direction of the battery body; when the first direction is the width direction of the battery body, the second direction is the length direction of the battery body.

[0051] like Figure 2 and Figure 3 As shown, the number of the first curved connection line 5 can be one or more, and the first curved connection line 5 is arranged on the first surface. The first curved connection line 5 extends along the second direction in a wavy shape, that is, it is arranged along the second direction from the first end to the second end of the first curved connection line 5, and the first curved connection line 5 is wavy as a whole, or in other words, along the first direction, the edges on both sides of the first curved connection line 5 are wavy lines.

[0052] The first end of the first curved connection line 5 is electrically connected to the end region of the first fine grid 2 close to the first side 4. The end region of the first fine grid 2 close to the first side 4 refers to the portion of the first fine grid 2 closer to the first side 4. The length of the end region of the first fine grid 2 close to the first side 4 may be within 20% of the length of the battery body along the first direction. For example, the length of the end region of the first fine grid 2 close to the first side 4 is 2%, 5%, 8%, 10%, 12%, 15%, 18% or 20% of the width of the battery body along the first direction. The first end of the first curved connection line 5 is electrically connected to any position in the end region of the first fine grid 2 close to the first side 4. In addition, the first curved connection line 5 and the first fine grid 2 are an integral structure, that is, the first curved connection line 5 and the first fine grid 2 can be manufactured together in the same step.

[0053] By adopting the above technical solution, the current collected by the first fine grid 2 in the larger area of ​​the doped semiconductor layer is transmitted to the first curved connecting line 5, and then transmitted to other components through the first curved connecting line 5. When the amount of current collected by the doped semiconductor layer is large, the first curved connecting line 5 plays the role of current shunting, which can improve the current transmission efficiency and thus improve the photoelectric conversion efficiency of the back contact battery. In addition, the first curved connecting line 5 extends along the second direction, which is roughly perpendicular to the extension direction of the first fine grid 2. If the connecting line extends along a straight line, it is easy to cause breakage during the manufacturing process, affecting the current transmission; based on this, the first curved connecting line 5 in the present application is wavy, and during the manufacturing process, the first curved connecting line 5 is smoother as a whole and has a higher quality; for example, when the first curved connecting line 5 is screen-printed, the wavy first curved connecting line 5 can bypass the grid intersection, thereby improving the yield of the first curved connecting line 5.

[0054] In some embodiments, Figure 1 As shown, the back contact battery also includes a first pad 6 disposed on the first surface and close to the first edge 4. Specifically, the back contact battery includes a plurality of columns of pads, and the plurality of columns of pads are spaced apart on the first surface along the first direction. Specifically, along the first direction, the plurality of columns of pads are sequentially arranged on the first surface, and there is a preset spacing between two adjacent columns of pads. Each column of pads includes a plurality of pads arranged along the second direction. The polarities of the plurality of pads in the same column are the same; the polarities of the pads in two adjacent columns are opposite, for example Figure 1 From left to right, the polarities of the first column of pads and the second column of pads are opposite, and the polarities of multiple pads in the first column are the same, and the polarities of multiple pads in the second column are the same. Among them, the column of pads closest to the first side 4 is the first column of pads, for example Figure 1 The leftmost row of pads is the first row of pads; the pads in the first row that are closest to the edge of the battery body along the second direction are the first pads 6, that is, Figure 1 The uppermost and lowermost pads in the first row of pads are first pads 6 .

[0055] In some embodiments, the area of ​​the first pad 6 is greater than the area of ​​the remaining pads in the same column (except the first and last pads), that is, the orthographic projection area of ​​the first pad 6 on the first surface is greater than the orthographic projection area of ​​the remaining pads in the same column on the first surface. Specifically, along the second direction, the length of the first pad 6 is greater than the length of the remaining pads in the same column; and / or, along the first direction, the width of the first pad 6 is equal to the width of the remaining pads in the same column, and the first pad 6 and the remaining pads in the same column are aligned along the second direction. With this technical solution, the first pad 6 is conductively connected to the plurality of first fine grids 2, so that the current collected by the plurality of first fine grids 2 can be promptly derived by using the first pad 6 with a larger area, thereby further improving the current transmission efficiency.

[0056] The second end of the first curved connecting line 5 is electrically connected to the first pad 6. In this way, the current collected by the first fine grid 2 can be transmitted to the first pad 6 through the first curved connecting line 5 and then to the outside of the back contact battery.

[0057] In some embodiments, the second end of the first curved connecting wire 5 is overlapped on the side of the first pad 6 away from the battery body. In this way, after lamination, the second end of the first curved connecting wire 5 is directly pressed on the first pad 6, which can prevent the second end of the first curved connecting wire 5 from being separated from the first pad 6, thereby improving the stability of the electrical contact between the second end of the first curved connecting wire 5 and the first pad 6.

[0058] In some embodiments, the first end of the first curved connecting line 5 does not overlap the first fine grid 2. Figure 3 In the middle A region, the first end of the first curved connection line 5 only needs to contact the side of the first fine grid 2 close to the first pad 6, and the first end of the first curved connection line 5 does not need to overlap the side of the first fine grid 2 away from the battery body. This arrangement can prevent the distance S between the first end of the first curved connection line 5 and the edge of the doped semiconductor layer of the same polarity from being too small, thereby reducing the risk of leakage.

[0059] In order to facilitate the alignment of the second end of the first curved connecting line 5 with the first pad 6, the first pad 6 has a protrusion 61 protruding toward one side of the first curved connecting line 5, and the second end of the first curved connecting line 5 is electrically connected to the protrusion 61. Optionally, the second end of the first curved connecting line 5 can be overlapped on the side of the protrusion 61 away from the battery body. With this technical solution, during the manufacturing process, the second end of the first curved connecting line 5 can be directly formed on the side of the protrusion 61 away from the battery body, which is conducive to the processing and positioning of the first curved connecting line 5.

[0060] In some embodiments, there is at least one first fine grid 2 between the first end and the second end of the first curved connecting line 5. That is, along the second direction, at least one first fine grid 2 passes between the first end and the second end of the first curved connecting line 5; for example Figure 3 In the embodiment, there is a first fine grid 2 passing through the area between the first end and the second end. Moreover, the first fine grid 2 located between the first end and the second end of the first curved connecting line 5 is electrically connected to the middle of the first curved connecting line 5, that is, all the first fine grids 2 passing between the first end and the second end are connected to the middle of the first curved connecting line 5. It can be understood that the middle of the first curved connecting line 5 can be any position between the first end and the second end. With this technical solution, the current collected by multiple first fine grids 2 can be transmitted to the first pad 6 through the first curved connecting line 5, further improving the current transmission efficiency.

[0061] In some embodiments, Figure 2 and Figure 4 As shown, the back contact battery further includes an edge busbar 3, and along the second direction, the plurality of first fine grids 2 between the first pad 6 and the edge of the battery body are electrically connected to the first pad 6 through the edge busbar 3. Specifically, the edge busbar 3 extends along the second direction, and the ends of the plurality of first fine grids 2 between the first pad 6 and the edge of the battery body are conductively connected to the edge busbar 3, so that the edge busbar 3 is used to transmit the current collected by the plurality of first fine grids 2 to the first pad 6. In view of the fact that the edge busbar 3 needs to collect the current of the plurality of first fine grids 2, the width of the edge busbar 3 can be set wider to improve the current transmission efficiency.

[0062] like Figure 2 As shown, the edge busbar 3 is connected to the first pad 6 via at least one second curved connection line 11 extending along the first direction, so that the current collected by the edge busbar 3 is timely transmitted to the first pad 6 by the second curved connection line 11. The number of the second curved connection lines 11 can be one, two, three or more, for example Figure 4 The number of the second curved connecting line 11 is one. Figure 6 In the embodiment, the number of the second curved connection lines 11 is two. In addition, at least one connection line extending along a straight line may be provided between the edge bus bar 3 and the first pad 6, which is not limited here.

[0063] In some embodiments, the first end of the second curved connecting wire 11 is overlapped on the side of the edge bus bar 3 away from the battery body. In this way, after lamination, the first end of the second curved connecting wire 11 is directly pressed on the edge bus bar 3, which can prevent the first end of the second curved connecting wire 11 from being separated from the edge bus bar 3, thereby improving the stability of the electrical contact between the first end of the second curved connecting wire 11 and the edge bus bar 3.

[0064] In some embodiments, the second end of the second curved connecting wire 11 is overlapped on the side of the first pad 6 away from the battery body. In this way, after lamination, the second end of the second curved connecting wire 11 is directly pressed on the first pad 6, which can prevent the second end of the second curved connecting wire 11 from being separated from the first pad 6, thereby improving the stability of the electrical contact between the second end of the second curved connecting wire 11 and the first pad 6.

[0065] Considering that the first curved connecting line 5 is mainly used to collect the current collected by multiple first fine grids 2, and the second curved connecting line 11 is mainly used to shunt the current between the edge bus grid 3 and the first pad 6, the current flowing through the first curved connecting line 5 is greater than the current flowing through the second curved connecting line 11. The width of the first curved connecting line 5 can be greater than the width of the second curved connecting line 11 to ensure the normal transmission of current, and at the same time make the width of the curved connecting line adapt to its internal current to avoid waste of raw materials.

[0066] In view of the fact that the first curved connection line 5 needs to collect the current collected by multiple first fine grids 2, the width of the first curved connection line 5 can be set wider to ensure the normal transmission of current. Specifically, the width of the first curved connection line 5 is W1, 30μm≤W1≤70μm. For example, the width of the first curved connection line 5 is 30μm, 32μm, 35μm, 38μm, 40μm, 42μm, 45μm, 48μm, 50μm, 52μm, 55μm, 58μm, 60μm, 62μm, 65μm, 68μm or 70μm, etc. By adopting this technical solution, the width W1 of the first curved connection line 5 is set within a reasonable range, which can prevent the first curved connection line 5 from being too narrow to affect the current transmission efficiency, and prevent the first curved connection line 5 from being too wide to avoid waste of raw materials.

[0067] In some embodiments, the width of the second curved connecting line 11 is W2, 20μm≤W2≤50μm. For example, the width W2 of the second curved connecting line 11 is 20μm, 22μm, 25μm, 28μm, 30μm, 32μm, 35μm, 38μm, 40μm, 42μm, 45μm, 48μm or 50μm, etc. By adopting this technical solution, the width W2 of the second curved connecting line 11 is set within a reasonable range, which can prevent the second curved connecting line 11 from being too narrow to affect the current transmission efficiency, and prevent the second curved connecting line 11 from being too wide to avoid the waste of raw materials.

[0068] The second curved connecting line 11 is wavy and extends along the first direction, that is, it is arranged from one end of the second curved connecting line 11 to the other end along the first direction, and the second curved connecting line 11 is wavy as a whole, or in other words, along the second direction, the two side edges of the first curved connecting line 5 are wavy lines. With this technical solution, the second curved connecting line 11 plays the role of current shunting, which can improve the uniformity and transmission efficiency of the current, thereby improving the photoelectric conversion efficiency of the back contact battery. In addition, the second curved connecting line 11 is wavy, and during the manufacturing process, the first curved connecting line 5 is smoother as a whole, and the quality of the formation is higher.

[0069] In some embodiments, Figure 7 As shown, the wavelength of the bending of the first curved connecting line 5 is L1; Figure 8 As shown, the wavelength of the second curved connecting line 11 is L2. Among them, |L1-L2|≤5μm; in this way, the wavelength L1 of the first curved connecting line 5 and the wavelength L2 of the second curved connecting line 11 are nearly equal, thereby ensuring that the current flowing through the first curved connecting line 5 and the second curved connecting line 11 is more uniform, preventing excessive concentration of local current. Exemplarily, |L1-L2| can be 5μm, 4μm, 3μm, 2μm or 1μm, etc.

[0070] In some embodiments, if the wavelength L1 of the first curved connecting line 5 is too small, the current transmission path is too long, resulting in a high transmission resistance; if the wavelength L1 of the first curved connecting line 5 is too large, it is easy to cause breakage during the manufacturing process, affecting the normal transmission of the current. In view of the above two situations, in this technical solution, 200μm≤L1≤300μm, to ensure the normal transmission of the current while preventing the current transmission path of the first curved connecting line 5 from being too long, thereby reducing the current transmission resistance. Exemplarily, L1 can be 200μm, 210μm, 220μm, 230μm, 240μm, 250μm, 260μm, 270μm, 280μm, 290μm or 300μm, etc.

[0071] In other embodiments, if the wavelength L2 of the second curved connecting line 11 is too small, the current transmission path is too long, resulting in a higher transmission resistance; if the wavelength L2 of the second curved connecting line 11 is too large, it is easy to cause breakage during the manufacturing process, affecting the normal transmission of current. In view of the above two situations, in this technical solution, 200μm≤L2≤300μm, to ensure the normal transmission of current while preventing the current transmission path of the second curved connecting line 11 from being too long, thereby reducing the current transmission resistance. Exemplarily, L2 can be 200μm, 210μm, 220μm, 230μm, 240μm, 250μm, 260μm, 270μm, 280μm, 290μm or 300μm, etc.

[0072] In some embodiments, Figure 2 and 3 As shown, there are multiple first curved connecting wires 5, so that the current collected by the first fine grid 2 is transmitted to the first welding pad 6 by using multiple first curved connecting wires 5, which further improves the current transmission efficiency. When one of the first curved connecting wires 5 fails, the remaining first curved connecting wires 5 can still transmit current normally, thereby improving the stability performance of the back contact battery.

[0073] Specifically, the plurality of first curved connecting wires 5 may be located on the same side of the first pad 6 along the second direction, for example Figure 3 In the embodiment, the plurality of first curved connecting wires 5 are all located on the upper side of the first pad 6. Alternatively, the plurality of first curved connecting wires 5 may be located on both sides of the first pad 6 along the second direction, for example Figure 5 In the embodiment, at least one first curved connection line 5 is located on the upper side of the first pad 6, and at least one first curved connection line 5 is located on the lower side of the first pad 6. With such an arrangement, the current collected by the first fine grid 2 located on the upper side and the lower side of the first pad 6 can be transmitted to the first pad 6 via the first curved connection line 5, further improving the current transmission efficiency.

[0074] In some embodiments, along the first direction, the crests of the plurality of first curved connecting wires 5 are aligned and the troughs of the plurality of first curved connecting wires 5 are aligned. Specifically, the crests of the plurality of first curved connecting wires 5 located on the same side of the first pad 6 are aligned and the troughs of the plurality of first curved connecting wires 5 are aligned, for example, the crests of the plurality of first curved connecting wires 5 located on the upper side or the lower side of the first pad 6 are aligned and the troughs of the plurality of first curved connecting wires 5 are aligned. Such an arrangement makes the current on the upper side and the lower side of the first pad 6 more uniform, preventing the current from being excessively concentrated locally.

[0075] If the first curved connecting line 5 and the first side 4 of the battery body are all set to doped semiconductor layers of the same polarity, it will cause excessive concentration of current collection in this area. In order to further alleviate the problem of excessive concentration of current collection, in this embodiment, at least one second fine grid 1 forms a bending section 12 at the end close to the first side 4, and the bending section 12 is at least partially located between the first curved connecting line 5 and the first side 4. Specifically, the doped semiconductor layer of the same polarity as the second fine grid 1 extends between the first curved connecting line 5 and the first side 4, and the bending section 12 of the second fine grid 1 is used to collect the current of the doped semiconductor layer of the same polarity as the second fine grid 1 between the first curved connecting line 5 and the first side 4. In this way, the bending section 12 of the second fine grid 1 and the first fine grid 2 are used to derive the current in the area between the first side 4 and the first curved connecting line 5, which can not only alleviate the problem of excessive concentration of current collection, but also help to reduce the current difference of doped semiconductor layers with opposite polarities.

[0076] Of course, the end of the second fine grid 1 may not be provided with the bent section 12, and the second fine grid 1 is disconnected at the first bent connecting line 5 to prevent leakage.

[0077] In some embodiments, the bending section 12 includes a third connecting line 121 and at least one sub-fine grid, the third connecting line 121 extends along the second direction, the sub-fine grid extends along the first direction, one end of the sub-fine grid is electrically connected to the third connecting line 121, and one end of the third connecting line 121 is electrically connected to the main body of the second fine grid 1 extending along the first direction. Figure 5 As shown, the number of sub-fine gates can be two; or Figure 6 As shown, the number of sub-fine grids can also be one; of course, the number of sub-fine grids can also be three or more. The second fine grid 1 and its bending section 12 can be integrally formed, which is convenient for manufacturing and processing, and prevents electrical connection failure of the bending section 12.

[0078] like Figure 4As shown, the third connection line 121 can extend in a wavy shape. That is, the third connection line 121 extends in a wavy shape along the second direction, that is, it is arranged from the first end to the second end of the third connection line 121 along the second direction, and the third connection line 121 is wavy as a whole, or in other words, along the first direction, the two side edges of the third connection line 121 are wavy lines. During the manufacturing process, the third connection line 121 is smoother as a whole, and the quality of the formation is higher; for example, when the third connection line 121 is screen-printed, the wavy third connection line 121 can bypass the grid intersection, thereby improving the yield of the third connection line 121.

[0079] In the present application, the first fine grid 2, the second fine grid 1, the first curved connecting line 5 and / or the second curved connecting line 11 can be formed by screen printing, electroplating, sputtering or evaporation. In addition, the first fine grid 2, the second fine grid 1, the first curved connecting line 5 and / or the second curved connecting line 11 can be made of silver, copper, aluminum and alloys thereof.

[0080] In some embodiments, Figure 1 As shown, the row of pads closest to the second side 7 is the last row of pads, for example Figure 1 The pads on the rightmost row are the pads in the last row; the pads in the last row that are closest to the edge of the semiconductor substrate along the second direction are the second pads 13, that is, Figure 1 The uppermost and lowermost pads in the middle and last row of pads are second pads 13. The second pads 13 are electrically connected to at least one second fine grid 1. Specifically, the second pads 13 and the second fine grid 1 can be directly electrically connected without a connecting wire. In addition, the second pads 13 and the edge bus bar 3 near the second side 7 can be electrically connected through a connecting strip extending in a straight line along the first direction.

[0081] In some embodiments, the cell body includes a semiconductor substrate, a first doped semiconductor layer 8 and a second doped semiconductor layer 9 .

[0082] The first doped semiconductor layer 8 and the second doped semiconductor layer 9 are both arranged on the first surface, and the first doped semiconductor layer 8 and the second doped semiconductor layer 9 are alternately spaced and distributed along the second direction. Specifically, the first doped semiconductor layer 8 and the second doped semiconductor layer 9 can be alternately spaced and distributed in strips, or can be alternately spaced and distributed in interdigitated shapes. An isolation region 10 is provided between the first doped semiconductor layer 8 and the second doped semiconductor layer 9 to reduce the carrier recombination rate at the lateral boundary between the first doped semiconductor layer 8 and the second doped semiconductor layer 9, which is beneficial to improving the photoelectric conversion efficiency of the back contact battery. In addition, the doping types of the first doped semiconductor layer 8 and the second doped semiconductor layer 9 are opposite, so as to collect and extract electrons and holes respectively, which is beneficial to form photocurrent.

[0083] In actual application, the material of the semiconductor substrate can be selected from materials such as silicon (Si) or germanium (Ge) or materials such as gallium arsenide (GaAs). Obviously, in terms of conductivity type, the semiconductor substrate can be an intrinsic conductive substrate, an n-type conductive substrate or a p-type conductive substrate. Optionally, the semiconductor substrate is a p-type conductive substrate or an n-type conductive substrate. Compared with the intrinsic conductive substrate, the p-type conductive substrate or the n-type conductive substrate has better conductivity, so that the final solar cell has a lower body resistivity, thereby improving the efficiency of the solar cell.

[0084] In addition, the materials of the first doped semiconductor layer 8 and the second doped semiconductor layer 9 may be silicon (Si), germanium (Ge), silicon carbide (SiCx) or gallium arsenide (GaAs), etc. The first doped semiconductor layer 8 may be additionally formed on the semiconductor substrate by a deposition technique, or may be formed in the semiconductor substrate by diffusion, ion implantation, etc.

[0085] In terms of conductivity type, the first doped semiconductor layer 8 may be an n-type doped layer, and the second doped semiconductor layer 9 may be a p-type doped layer; or, the first doped semiconductor layer 8 may be a p-type doped layer, and the second doped semiconductor layer 9 may be an n-type doped layer.

[0086] Multiple first fine gates 2 are respectively arranged on multiple first doped semiconductor layers 8, so that the first fine gates 2 can be used to promptly conduct the current collected by the first doped semiconductor layer 8; multiple second fine gates 1 are respectively arranged on multiple second doped semiconductor layers 9, so that the second fine gates 1 can be used to promptly conduct the current collected by the second doped semiconductor layer 9.

[0087] The pad is electrically connected to the first fine grid 2 or the second fine grid 1, for example Figure 1 In the embodiment, the plurality of pads included in the first column of pads are respectively conductively connected to the plurality of first fine grids 2; the plurality of pads included in the second column of pads are respectively conductively connected to the plurality of second fine grids 1.

[0088] The back contact cell also includes a passivation layer, which is located on the side of the first doped semiconductor layer 8 and the second doped semiconductor layer 9 away from the semiconductor substrate. The passivation layer can passivate the surface of the doped semiconductor layer, reduce its carrier recombination rate, and further improve the photoelectric conversion efficiency of the solar cell. The material of the passivation layer may include one or more of silicon nitride, silicon oxynitride, and silicon oxide. In addition, the passivation layer can be a single-layer structure or a multi-layer structure. As for the thickness of the passivation layer, it only needs to meet the passivation effect and ensure the contact performance of the fine gate and the doped semiconductor layer.

[0089] The first fine gate 2 and the second fine gate 1 are formed on the side of the passivation layer away from the semiconductor substrate. Specifically, the first fine gate 2 passes through the passivation layer to be electrically connected to the first doped semiconductor layer 8, and the second fine gate 1 passes through the passivation layer to be electrically connected to the second doped semiconductor layer 9. The passivation layer may be provided with a first opening corresponding to the first doped semiconductor layer 8 and a second opening corresponding to the second doped semiconductor layer 9, the first fine gate 2 passes through the first opening to be electrically connected to the first doped semiconductor layer 8, and the second fine gate 1 passes through the second opening to be electrically connected to the second doped semiconductor layer 9. Alternatively, the first fine gate 2 passes through the passivation layer to be electrically connected to the first doped semiconductor layer 8 by burning through, and the second fine gate 1 passes through the passivation layer to be electrically connected to the second doped semiconductor layer 9 by burning through.

[0090] In actual application, the first doped semiconductor layer 8 includes one or more of polycrystalline silicon, amorphous silicon, nanocrystalline silicon and microcrystalline silicon. In this case, the doped polycrystalline silicon layer has higher carrier transport characteristics. Therefore, when the first doped semiconductor layer 8 is a doped polycrystalline silicon layer, the carrier transport efficiency is higher, which is conducive to improving the photoelectric conversion efficiency of the back contact battery. Of course, the second doped semiconductor layer 9 can also be one or more of doped amorphous silicon, doped microcrystalline silicon, and doped nanocrystalline silicon.

[0091] In some embodiments, a first interface layer is provided between the first doped semiconductor layer 8 and the semiconductor substrate; and / or a second interface layer is provided between the second doped semiconductor layer 9 and the semiconductor substrate. The passivation contact structure composed of the interface layer and the semiconductor layer has an excellent interface passivation effect, and can realize the selective collection of carriers, reduce the carrier recombination rate in the area where the semiconductor layer is formed on the surface of the semiconductor substrate, and further improve the photoelectric conversion efficiency of the solar cell. The material and thickness of the first interface layer can be set according to the material of the first doped semiconductor layer 8 and actual needs, and the material and thickness of the second interface layer can be set according to the material of the second doped semiconductor layer 9 and actual needs, and are not specifically limited here.

[0092] For example, the first doped semiconductor layer 8 may be a doped polysilicon layer, and the first interface layer may be a tunneling oxide layer. The second doped semiconductor layer 9 may be a doped polysilicon layer, and the second interface layer may be a tunneling oxide layer.

[0093] Of course, when the first doped semiconductor layer 8 includes one or more of doped amorphous silicon, doped microcrystalline silicon, and doped nanocrystalline silicon, the first interface layer includes one or more of an intrinsic amorphous silicon layer, an intrinsic microcrystalline silicon layer, and an intrinsic nanocrystalline silicon. When the second doped semiconductor layer 9 includes one or more of doped amorphous silicon, doped microcrystalline silicon, and doped nanocrystalline silicon, the second interface layer includes one or more of an intrinsic amorphous silicon layer, an intrinsic microcrystalline silicon layer, and an intrinsic nanocrystalline silicon.

[0094] In some embodiments, along the second direction, the electrode pattern (including the first fine grid 2, the second fine grid 1, the first pad 6, the first curved connection line 5, the second curved connection line 11, the edge bus 3 and / or the bending segment, etc.) is symmetrically arranged along the center line axis.

[0095] The embodiment of the present application also provides a photovoltaic module, which includes an electrical connector and a solar cell provided by any of the above embodiments. The electrical connector can be conductively connected to a plurality of first fine grids 2. Specifically, the electrical connector can extend along the second direction, and each electrical connector is conductively connected to a plurality of first fine grids 2 through a plurality of pads in a column of pads, so as to use the electrical connector to conduct current to the outside of the back contact cell. The electrical connector can be specifically a busbar or a welding strip.

[0096] Compared with the prior art, the beneficial effects of the photovoltaic module provided in the embodiment of the present application are the same as the beneficial effects of the above-mentioned solar cell, which will not be elaborated here.

[0097] In some embodiments, the end of the electrical connector is arranged to overlap at least a portion of the first curved connection line 5. That is, along the second direction, the electrical connector and the first curved connection line 5 at least partially overlap. Such an arrangement can increase the contact area between the electrical connector and the first pad 6 and the first curved connection line 5, thereby reducing the contact resistance and improving the current transmission efficiency. At the same time, in order to prevent the first curved connection line 5 from being welded off by the electrical connector, the width of the first curved connection line 5 needs to be greater than the width of the first fine grid 2 and the second fine grid 1, and greater than the width of the second curved connection line 11.

[0098] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0099] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A back contact battery, characterized in that: include: The battery body comprises a first surface and a second surface arranged opposite to each other, wherein the first surface has a first side and a second side arranged opposite to each other along a first direction; A plurality of first fine grids and a plurality of second fine grids are arranged on the first surface, and extend along a first direction and are alternately distributed along a second direction, the first direction intersects with the second direction, and the first fine grids and the second fine grids have different properties; The first curved connecting line is arranged on the first surface and extends in a wavy shape along the second direction. The first end of the first curved connecting line is electrically connected to the end area of ​​the first fine grid close to the first edge, and the first curved connecting line and the first fine grid are an integral structure.

2. The back contact cell according to claim 1, characterized in that: The back contact cell also includes a first pad disposed on the first surface and close to the first edge; The second end of the first meandering connection line is electrically connected to the first pad.

3. The back contact battery according to claim 2, characterized in that: The second end of the first curved connecting line is overlapped on a side of the first welding pad facing away from the battery body.

4. The back contact cell according to claim 2, characterized in that: The first pad has a protruding portion protruding toward one side of the first meandering connection line, and the second end of the first meandering connection line is electrically connected to the protruding portion.

5. The back contact cell according to claim 1 or 2, characterized in that: At least one first fine grid is disposed between the first end and the second end of the first curved connecting line, and the first fine grid located between the first end and the second end of the first curved connecting line is electrically connected to the middle portion of the first curved connecting line.

6. The back contact cell according to claim 2, characterized in that: The invention also includes an edge bus bar extending between the first pad and the first edge and along the second direction, wherein the edge bus bar is connected to the first pad via at least one second bent connection line extending along the first direction.

7. The back contact cell according to claim 6, characterized in that: The first end of the second curved connection line is overlapped on a side of the edge bus bar away from the battery body; and / or the second end of the second curved connection line is overlapped on a side of the first pad away from the battery body.

8. The back contact cell according to claim 6, characterized in that: The width of the first curved connection line is greater than that of the second curved connection line; and / or the width of the first curved connection line is W1, 30μm≤W1≤70μm; and / or the width of the second curved connection line is W2, 20μm≤W2≤50μm.

9. The back contact battery according to claim 6, characterized in that: The second curved connecting line extends in a wave shape; The wavelength of the bending of the first curved connecting line is L1, and the wavelength of the bending of the second curved connecting line is L2, |L1-L2|≤5μm; and / or, 200μm≤L1≤300μm; and / or, 200μm≤L2≤300μm.

10. The back contact cell according to claim 1, characterized in that: The number of the first curved connecting lines is multiple; Along the first direction, the crests of the plurality of first curved connecting lines are aligned and the troughs of the plurality of first curved connecting lines are aligned.

11. The back contact cell according to claim 1, characterized in that: At least one of the second fine grids has a bent section at its end close to the first edge, and the bent section is at least partially located between the first curved connecting line and the first edge; The bending section includes a third connecting line and at least one sub-fine grid, the third connecting line extends along the second direction, the sub-fine grid extends along the first direction and one end of the sub-fine grid is electrically connected to the third connecting line.

12. The back contact cell according to claim 11, characterized in that: The third connecting line extends in a wave shape.

13. A photovoltaic module, characterized in that: It comprises a back contact cell as claimed in any one of claims 1 to 12 and an electrical connector, wherein the electrical connector is electrically connected to a plurality of the first fine grids.

14. The photovoltaic module according to claim 13, characterized in that: The end of the electrical connector is overlapped with at least a portion of the first curved connecting line.

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