A back contact cell and photovoltaic module

Abstract

The application discloses a back contact cell and a photovoltaic module. The back contact cell comprises a substrate, a plurality of first current collecting grid lines and a plurality of second current collecting grid lines, which are alternately arranged along a first direction and extend along a second direction, a plurality of groups of electrically combined unit groups, which are equidistantly arranged along the second direction, each group of electrically combined unit groups comprising first electrically combined units and second electrically combined units which extend along the first direction and are sequentially and equidistantly arranged along the second direction and are connected with the first current collecting grid lines and the second current collecting grid lines respectively, in the second direction, the distance between the first electrically combined units and the second electrically combined units in one group of electrically combined unit groups is less than the distance between the first electrically combined units in the group of electrically combined unit groups and the second electrically combined units in an adjacent group of electrically combined unit groups, the width of the first electrically combined units is M1, the width of the second electrically combined units is M2, and the distance between the extension center lines of the first electrically combined units and the second electrically combined units in each group of electrically combined unit groups is D1.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to a back contact cell and a photovoltaic module. BACKGROUND

[0002] The back contact cell is a cell in which the emitter and base contact electrodes are both placed on the back (non-light-receiving surface or non-front surface) of the cell, and the light-receiving surface or front surface of the cell is not blocked by any metal electrode, thereby effectively increasing the short-circuit current of the cell, and the back surface can accommodate a wider metal grid to reduce the series resistance and thereby improve the fill factor.

[0003] For the back contact cell, the electrode structure is the core technology of the cell, and a reasonable electrode pattern can better bring out the advantages of the back contact cell technology. The existing back contact cell collects photo-generated current through the fine grid of the back PN area in a forked manner and collects the current collected through the back PN main grid. How to optimize the electrode arrangement and improve the current collection efficiency has become a problem to be solved by those skilled in the art. SUMMARY

[0004] The purpose of the present application is to provide a back contact cell and a photovoltaic module to optimize the electrode arrangement and improve the current collection efficiency.

[0005] In a first aspect, the present application provides a back contact cell, comprising:

[0006] a substrate having opposite first and second surfaces;

[0007] a plurality of first and second current collecting grid lines, the first and second current collecting grid lines being alternately arranged on the first surface along a first direction, the first and second current collecting grid lines extending along a second direction, the first and second current collecting grid lines having opposite polarities, the first and second directions intersecting each other;

[0008] a plurality of groups of electrical junction units arranged equidistantly on the first surface along the second direction, each group of electrical junction units comprising first and second electrical junction units arranged equidistantly along the second direction, the first and second electrical junction units extending along the first direction, the first electrical junction units being connected to the first current collecting grid lines, and the second electrical junction units being connected to the second current collecting grid lines;

[0009] In the second direction, the distance between the first and second electrical combination units in each group of electrical combination units is less than the distance between the first electrical combination unit in the group and the second electrical combination unit in the adjacent group, the width of the first electrical combination unit is M1, the width of the second electrical combination unit is M2, and the distance between the extension center line of the first electrical combination unit and the extension center line of the second electrical combination unit in each group of electrical combination units is D1,

[0010]

[0011] In the above technical solution, the first surface of the back contact cell is provided with first and second current collection grid lines with opposite polarities arranged alternately in the first direction and first and second electrical combination units arranged alternately in the second direction, the first electrical combination unit is connected with the first current collection grid line, the second electrical combination unit is connected with the second current collection grid line, the current of the back contact cell is collected through the first and second current collection grid lines, the current of the first current collection grid line is collected through the first electrical combination unit and is led out to the interconnection, the current of the second current collection grid line is collected through the second electrical combination unit and is led out to the interconnection, one first electrical combination unit and one second electrical combination unit form a group of electrical combination units, and multiple groups of electrical combination units are arranged at equal intervals in the second direction. Since the first and second electrical combination units have widths, and considering the insulation distance between the first and second electrical combination units with opposite polarities, the distance D1 between the extension center line of the first electrical combination unit and the extension center line of the second electrical combination unit in each group of electrical combination units needs to be reduced by half the width of the first electrical combination unit and then by half the width of the second electrical combination unit, and is greater than 10 μm, so as to ensure that the first and second electrical combination units in each group of electrical combination units are as close as possible while there is no contact and the insulation distance is ensured, and the first and second electrical combination units are arranged as close as possible, so as to change the distribution of the positive and negative carrier collection areas and better collect the current and improve the current collection efficiency.

[0012] In some possible implementation manners, Further considering that the first and second electrical combination units may be offset during printing, D1 needs to be greater than 150 μm and less than 600 μm after being reduced by half the width of the first electrical combination unit and then by half the width of the second electrical combination unit, so as to prevent the distance between the first and second electrical combination units from being too large and being not conducive to current collection.

[0013] In some possible implementations, the distance from the extension center line of the first electrical junction unit located at the outermost side of the back contact battery to the end of the adjacent first current collecting grid line is greater than Alternatively, the distance from the extension center line of the second electrical junction unit located at the outermost side of the back contact battery to the end of the adjacent second current collecting grid line is greater than Since the first electrical junction unit and the second electrical junction unit each have a width, considering that the first electrical junction unit located at the edge cannot exceed the end of the first current collecting grid line, and the second electrical junction unit located at the edge cannot exceed the end of the second current collecting grid line, in order to facilitate the connection of the first electrical junction unit and the second electrical junction unit with the interconnect, and avoid the risk of fragmentation of the edge of the back contact battery due to the connection of the interconnect, D2 and D2' are greater than D3 and D6 are greater than

[0014] In some possible implementations, the distance D2 from the extension center line of the first electrical junction unit located at the outermost side of the back contact battery to the end of the adjacent first current collecting grid line satisfies: 1300 μm < D1 ≤ D2. Since the minimum width of the first electrical junction unit and the second electrical junction unit is 1000 μm, considering that the insulating isolation distance between the first electrical junction unit and the second electrical junction unit with opposite polarity is 200 μm, and considering that the first electrical junction unit and the second electrical junction unit may each have an offset during printing, the offset distance is 50 μm, D1 needs to be greater than the sum of half the width of the first electrical junction unit, half the width of the second electrical junction unit, the offset distance of the first electrical junction unit and the second electrical junction unit, and the insulating isolation distance between the first electrical junction unit and the second electrical junction unit, that is, D1 > 1300 μm, and D1 cannot exceed D2, so as to avoid the distance D6 from the extension center line of the second electrical junction unit located at the outermost side of the back contact battery to the end of the adjacent second current collecting grid line being zero, and the second electrical junction unit being too close to the edge of the back contact battery, which is not conducive to the arrangement of the edge second electrical junction unit, and causes the risk of fragmentation of the edge of the back contact battery.

[0015] In some possible implementations, the distance between the extension center lines of two adjacent first electrical junction units is D4, and the distance D2 from the extension center line of the first electrical junction unit located at the outermost side of the back contact battery to the end of the adjacent first current collecting grid line satisfies: 1300 μm < D2 ≤ D4-D1, or 2600 μm < D2+D1 ≤ D4. In this way, by reasonably setting the distance D4 between the extension center lines of two adjacent first electrical junction units, the distance D2 from the extension center line of the first electrical junction unit located at the outermost side of the back contact battery to the end of the adjacent first current collecting grid line, and the distance D1 between the first electrical junction unit and the second electrical junction unit in each group of electrical junction units, the current collection efficiency can be improved, the risk of short circuit can be avoided, and the risk of fragmentation of the edge of the back contact battery can be reduced.

[0016] In some possible implementation manners, the distance from the extension center line of each of the two first electrically combined units located at the outermost side to the end of the adjacent first current collecting grid line is D2, the distance between the extension center lines of the two adjacent first electrically combined units is D4, and the ratio of D2 to D4 satisfies:

[0017] wherein X is the length of the back contact battery in the second direction, and Y is the number of the first electrically combined units.

[0018] In the case of adopting the technical scheme, the relationship between the distance D2 from the extension center line of the first electrically combined unit located at the outermost side to the end of the adjacent first current collecting grid line and the distance D4 between the extension center lines of the two adjacent first electrically combined units is determined according to the length of the back contact battery and the number of the first electrically combined units, so that the arrangement of the first electrically combined units on the back contact battery is reasonable, and the current collection efficiency can be improved, short circuit can be avoided, and the risk of fragmentation of the edge of the back contact battery can be reduced.

[0019] In some possible implementation manners, in the second direction, the ends of the first current collecting grid lines and the second current collecting grid lines are flush;

[0020] The distance from the extension center line of each of the two first electrically combined units located at the outermost side to the end of the adjacent first current collecting grid line is D2;

[0021] The distance between the extension center lines of the two adjacent first electrically combined units is D4;

[0022] The distance between the extension center lines of the two adjacent second electrically combined units is D5, and D4=D5;

[0023] The distance from the extension center line of the second electrically combined unit located at the outermost side to the end of the adjacent second current collecting grid line is D3;

[0024] The distance from the extension center line of the other second electrically combined unit located at the outermost side to the end of the adjacent second current collecting grid line is D6, and D3>D6;

[0025] The ratio of D3 to D5 satisfies:

[0026] Wherein, X is the length of the back contact battery in the second direction, and Y is the number of the second electrical junction units. In the case of adopting the technical scheme, the relationship between the distance D6 from the extension center line of the second electrical junction unit located at the outermost side to the end of the adjacent second current collection grid line and the distance D5 between the extension center lines of the adjacent two second electrical junction units is determined according to the length of the back contact battery and the number of the second electrical junction units, so that the arrangement of the second electrical junction unit on the back contact battery is reasonable, and the current collection efficiency is improved, short circuit is avoided, and the risk of chipping of the edge of the back contact battery is reduced.

[0027] In some possible implementation manners, the first electrical junction unit comprises a plurality of first electrical junction parts arranged at intervals in the first direction, and the first electrical junction part is connected with the first current collection grid line.

[0028] And / or, the second electrical junction unit comprises a plurality of second electrical junction parts arranged at intervals in the first direction, and the second electrical junction part is connected with the second current collection grid line.

[0029] In the case of adopting the technical scheme, the first electrical junction unit comprises a plurality of first electrical junction parts arranged at intervals, and the first current collection grid line is connected with the interconnector through the first electrical junction part. The second electrical junction unit comprises a plurality of second electrical junction parts arranged at intervals, and the second current collection grid line is connected with the interconnector through the second electrical junction part. Since the first electrical junction unit and the second electrical junction unit are both free of main grids, the electrode cost is reduced without affecting the current transmission efficiency.

[0030] In some possible implementation manners, the first electrical junction unit further comprises a first busbar line extending in the first direction, and the first busbar line is connected with the first electrical junction part.

[0031] And / or, the second electrical junction unit further comprises a second busbar line extending in the first direction, and the second busbar line is connected with the second electrical junction part.

[0032] In the case of adopting the technical scheme, the first electrical junction unit and the second electrical junction unit further comprise main grids, the current transmission path between the current collection grid lines is shortened through the main grids, the current transmission efficiency is further improved, and the carriers in the corresponding region of the back contact battery can be further collected through the main grids, and the photoelectric conversion efficiency of the battery is improved.

[0033] In a second aspect, the present application further provides a photovoltaic module, comprising:

[0034] A battery string formed by electrically connecting a plurality of back contact batteries as described in any one of the above;

[0035] An interconnector connected with the electrical junction unit group of the back contact battery;

[0036] And a packaging layer covering the surface of the battery string.

[0037] The beneficial effects of the photovoltaic module of the second aspect can be analyzed with reference to the beneficial effects of the first aspect and various implementation manners thereof, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0038] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

[0039] Figure 1 A schematic diagram of electrode arrangement of a back contact cell is provided for the embodiments of the present application;

[0040] Figure 2 A schematic diagram of partial electrode arrangement structure of a back contact cell is provided for the embodiments of the present application.

[0041] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings: DETAILED DESCRIPTION

[0042] In order to make the technical problems to be solved by the present application, technical solutions and beneficial effects more clearly understood, the following will be further described in detail in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and not to limit the present application.

[0043] It should be noted that when an element is referred to as being "fixed" 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.

[0044] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited. The meaning of "several" is one or more, unless otherwise explicitly and specifically limited.

[0045] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0046] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0047] For back contact cells, electrode structure is the core technology of the cell, and reasonable electrode pattern can better play the advantages of back contact cell technology. The existing back contact cell collects photo-generated current through the back PN area interdigital fine grid, and collects the current collected through the back PN main grid. How to optimize the electrode arrangement and improve the current collection efficiency has become a problem to be solved by those skilled in the art.

[0048] In a first aspect, as Figure 1 and Figure 2As shown, an embodiment of the present invention provides a back-contact battery, including a substrate, a plurality of first collecting grid lines 2, a plurality of second collecting grid lines 3 and a plurality of electrically coupled unit groups 1; wherein the substrate has a first surface and a second surface relative to each other, the first surface can be the backlight surface of the substrate, and the second surface can be the light-receiving surface (front surface) of the substrate; the first collecting grid lines 2 and the second collecting grid lines 3 are alternately arranged on the first surface along a first direction, the first collecting grid lines 2 and the second collecting grid lines 3 extend along a second direction, the polarities of the first collecting grid lines 2 and the second collecting grid lines 3 are opposite, the first collecting grid lines 2 and the second collecting grid lines 3 are used to collect the current generated by the photovoltaic of the back-contact battery, the first direction and the second direction intersect, and specifically can be Perpendicular to each other; multiple groups of electrical combination unit groups 1 are arranged at equal intervals on the first surface along the second direction, and each group of electrical combination unit groups 1 includes a first electrical combination unit 11 and a second electrical combination unit 12 arranged in sequence along the second direction. The first electrical combination unit 11 and the second electrical combination unit 12 both extend along the first direction, the first electrical combination unit 11 is connected to the first collecting grid line 2, and the second electrical combination unit 12 is connected to the second collecting grid line 3. The first electrical combination unit 11 is used to collect the current collected by the first collecting grid line 2, and the second electrical combination unit 12 is used to collect the current collected by the second collecting grid line 3. The first electrical combination unit 11 and the second electrical combination unit 12 are used to connect to the interconnection member to derive the current.

[0049] In the second direction, the distance between the extended center line of the first electrical combination unit 11 and the extended center line of the second electrical combination unit 12 in one electrical combination unit group 1 is less than the distance between the extended center line of the first electrical combination unit 11 in the electrical combination unit group 1 and the extended center line of the second electrical combination unit 12 in the adjacent electrical combination unit group 1, the width of the first electrical combination unit 11 is M1, the width of the second electrical combination unit 12 is M2, and the extended center line of the first electrical combination unit 11 in each electrical combination unit group 1 ( Figure 1 The extended center line of the second electrical combination unit 12 ( Figure 1 The distance between the two dotted lines is D1, and the relationship between D1, M1 and M1 is:

[0050] It should be noted that the multiple groups of electrical combination units 1 are arranged at equal intervals along the second direction. It can be understood that the multiple first electrical combination units 11 are arranged at equal intervals along the second direction, and the multiple second electrical combination units 12 are arranged at equal intervals along the second direction. The spacing between two adjacent first electrical combination units 11 is equal to the spacing between two adjacent second electrical combination units 12, and the first electrical junction units 11 and the second electrical combination units 12 are arranged alternately along the second direction.

[0051] In the technical solution, the first surface of the back contact cell is provided with first and second current collection grid lines 2 and 3 with opposite polarities arranged alternately in the first direction, and first and second electrical junction units 11 and 12 arranged alternately in the second direction, the first electrical junction unit 11 is connected with the first current collection grid line 2, and the second electrical junction unit 12 is connected with the second current collection grid line 3, wherein one first electrical junction unit 11 and one second electrical junction unit 12 adjacent and close to each other form a group of electrical junction unit groups 1, and a plurality of groups of electrical junction unit groups 1 are arranged at equal intervals in the second direction. Since the first and second electrical junction units 11 and 12 have a width, and considering the insulating isolation distance between the first and second electrical junction units 11 and 12 with opposite polarities, the distance D1 between the extension center line of the first electrical junction unit 11 and the extension center line of the second electrical junction unit 12 in each group of electrical junction unit groups 1 needs to be reduced by half of the width of the first electrical junction unit 11, and then by half of the width of the second electrical junction unit 12, and is greater than 10 μm, Specifically, it can be 11 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, 210 μm, 220 μm, 230 μm, 240 μm, 250 μm, 260 μm, 270 μm, 280 μm, 290 μm, 300 μm, 310 μm, 320 μm, 330 μm, 340 μm, 350 μm, 360 μm, 370 μm, 380 μm, 390 μm, 400 μm, 410 μm, 420 μm, 430 μm, 440 μm, 450 μm, 460 μm, 470 μm, 480 μm, 490 μm, 500 μm, 510 μm, 520 μm, 530 μm, 540 μm, 550 μm, 560 μm, 570 μm, 580 μm, 590 μm, 600 μm, etc., so as to ensure that the first and second electrical junction units 11 and 12 in each group of electrical junction unit groups 1 are as close as possible without contact and ensuring the insulation distance, and the first and second electrical junction units 11 and 12 are arranged as close as possible, so as to optimize the distribution of the positive and negative carrier collection areas corresponding to the first and second electrical junction units 11 and 12, and better collect current and improve current collection efficiency.

[0052] In some embodiments, the distance D1 between the extension center line of the first electrical junction unit 11 and the extension center line of the second electrical junction unit 12 in each group of electrical junction unit groups 1 needs to meet the following conditions, Since not only the insulating isolation distance between the first and second electrically combined units 11 and 12 with opposite polarities needs to be considered, but also the possible offset of the first and second electrically combined units 11 and 12 during printing needs to be considered, D1 needs to be reduced by half the width of the first electrically combined unit 11, and then reduced by half the width of the second electrically combined unit 12, and is greater than 150 μm and less than or equal to 600 μm, Specifically, it can be 151 μm, 155 μm, 160 μm, 165 μm, 170 μm, 175 μm, 180 μm, 185 μm, 190 μm, 195 μm, 200 μm, 205 μm, 210 μm, 215 μm, 220 μm, 225 μm, 230 μm, 240 μm, 250 μm, 260 μm, 270 μm, 280 μm, 290 μm, 295 μm, 300 μm, 310 μm, 320 μm, 330 μm, 340 μm, 350 μm, 360 μm, 370 μm, 380 μm, 390 μm, 400 μm, 410 μm, 420 μm, 430 μm, 440 μm, 450 μm, 460 μm, 470 μm, 480 μm, 490 μm, 500 μm, 510 μm, 520 μm, 530 μm, 540 μm, 550 μm, 560 μm, 570 μm, 580 μm, 590 μm, 600 μm, etc. A sufficient distance is reserved to ensure that the first and second electrically combined units 11 and 12 in each group of electrically combined unit groups 1 are as close as possible without contacting each other and to ensure the insulating distance. Moreover, it is not more than 600 μm, so as to avoid that the spacing between the first and second electrically combined units 11 and 12 is too large, which is not conducive to the collection of current.

[0053] In some embodiments, the distance D2 from the extension center line of the first electrically combined unit 11 located at the outermost side of the back contact battery to the end of the adjacent first current collecting grid line 2 is greater than Alternatively, the distance D3 from the extension center line of the second electrically combined unit 12 located at the outermost side of the back contact battery to the end of the adjacent second current collecting grid line 3 is greater than Since the first and second electrically combined units 11 and 12 each have a width, it is considered that the first electrically combined unit 11 located at the edge cannot exceed the end of the first current collecting grid line 2, and the second electrically combined unit 12 located at the edge cannot exceed the end of the second current collecting grid line 3, so as to facilitate the connection of the first and second electrically combined units 11 and 12 with the interconnect, and to avoid the risk of fragmentation of the edge of the back contact battery due to the connection of the interconnect, therefore, D2 is greater than D3 is greater than

[0054] It should be noted that, as Figure 1As shown, the first and second current collecting grid lines 2 and 3 have equal extension length in the second direction, and the end portions are flush. When the distance between the extension center line of the two first electrically combined units 11 located at the outermost side and the end portion of the adjacent first current collecting grid line 2 is D2, i.e. the distances are equal, since the second electrically combined units 12 are arranged staggered with the first electrically combined units 11 in the second direction, the distance between the extension center line of one of the two second electrically combined units 12 located at the outermost side and the end portion of the adjacent second current collecting grid line 3 is D3, and the distance between the extension center line of the other second electrically combined unit 12 located at the outermost side and the end portion of the adjacent second current collecting grid line 3 is D6, D3 and D6 are not equal, and D3 is greater than D6, 2D2=D3+D6. At this time, the smaller distance D6 is also greater than so that the two second electrically combined units 12 located at the outermost side do not exceed the end portion of the adjacent second current collecting grid line 3.

[0055] In addition, when the distance between the extension center line of one of the first electrically combined units 11 located at the outermost side of the back contact battery and the end portion of the adjacent first current collecting grid line 2 is D2, and the distance between the extension center line of the other first electrically combined unit 11 located at the outermost side of the back contact battery and the end portion of the adjacent first current collecting grid line 2 is D2', D2 and D2' can be equal or not equal, and D2' is also greater than In order to facilitate the description of the relationship between the distance between the extension center line of the first electrically combined unit 11 located at the outermost side of the back contact battery and the end portion of the adjacent first current collecting grid line 2 and other distances, the following will be described by taking D2 as an example, but D2' also satisfies the same relationship.

[0056] In some embodiments, the distance D2 between the extension center line of the first electrically combined unit 11 located at the outermost side of the back contact battery and the end portion of the adjacent first current collecting grid line 2 satisfies: 1300 μm < D1 < D2. Considering that the width M1 of the first electrically combined unit 11 can range from 1000 μm to 1200 μm, and the width M2 of the second electrically combined unit 12 can range from 1000 μm to 1200 μm, the minimum width of the first electrically combined unit 11 and the second electrically combined unit 12 is 1000 μm; at the same time, considering that the insulation isolation distance between the first electrically combined unit 11 and the second electrically combined unit 12 with opposite polarity is 0-200 μm, and considering that the first electrically combined unit 11 and the second electrically combined unit 12 can have a shift during printing, the shift distance is 0-50 μm, D1 needs to be greater than half the width of the first electrically combined unit 11, half the width of the second electrically combined unit 12, the shift distance of the first electrically combined unit 11 and the second electrically combined unit 12, and the insulation isolation distance between the first electrically combined unit 11 and the second electrically combined unit 12, i.e. When M1 and M2 are both minimum 1000 μm, then D1 > 1300 μm, and D1 can be 1301 μm, 1310 μm, 1320 μm, 1330 μm, 1340 μm, 1350 μm, 1360 μm, 1370 μm, 1380 μm, 1390 μm, 1400 μm, 1410 μm, 1420 μm, 1430 μm, 1440 μm, 1450 μm, 1460 μm, 1470 μm, 1480 μm, 1490 μm, 1500 μm, 1510 μm, 1520 μm, 1530 μm, 1540 μm, 1550 μm, 1560 μm, 1570 μm, 1580 μm, 1590 μm, 1600 μm, etc.

[0057] In addition, the first and second electrical bonding units 11 and 12 in each group of electrical bonding unit group 1 need to be welded with corresponding interconnects (such as solder strips) respectively, and since the welding precision of the interconnects is ± 600 μm, D1 > 600 + 600, so D1 > 1200 μm, but D1 cannot be too large, D1 cannot exceed D2, otherwise D1-D2=D6, as shown in Figure 1 D6 is less than 0, in order to avoid the distance D6 from the extension center line of the second electrical bonding unit 12 located at the outermost side of the back contact battery to the end of the adjacent second current collecting grid line 3 being zero, the second electrical bonding unit 12 being too close to the edge of the back contact battery, which is not conducive to the setting of the edge second electrical bonding unit 12, and there is a risk of chipping at the edge of the back contact battery. Therefore, in combination with D1 > 1200 μm, D1 > 1300 μm, D1 < D2, it is obtained that 1300 μm < D1 < D2.

[0058] For example, D2 can be 1301 μm, 1310 μm, 1320 μm, 1330 μm, 1340 μm, 1350 μm, 1360 μm, 1370 μm, 1380 μm, 1390 μm, 1400 μm, 1410 μm, 1420 μm, 1430 μm, 1440 μm, 1450 μm, 1460 μm, 1470 μm, 1480 μm, 1490 μm, 1500 μm, 1510 μm, 1520 μm, 1530 μm, 1540 μm, 1550 μm, 1560 μm, 1570 μm, 1580 μm, 1590 μm, 1600 μm, etc.

[0059] As shown in Figure 1As shown, in some embodiments, the distance between the extension center lines of two adjacent first electrically combined units 11 is D4, and the distance between the extension center line of the first electrically combined unit 11 located at the outermost side of the back contact battery and the end of the adjacent first current collecting grid line 2 is D2, which satisfies: 1300 pm < D2 < D4-D1, or, 2600 pm < D2+D1 < D4. Since it has been clarified in the above embodiments that Since the first electrically combined unit 11 located at the outermost side needs to be welded with the interconnect, the welding precision is ±600 pm, so D2 > 600 pm is required, and since the current transmission effect of the first current collecting grid line 2 is affected by the resistance and transmission distance of the first current collecting grid line 2, so D2 < D4 is required. Combining D2 > 600 pm and D2 < D4, we get 600 < D2 < D4, and then combining 1300 pm < D1 < D2 in the above embodiments, we can get 1300 pm < D2 < D4-D1, or, 2600 pm < D2+D1 < D4.

[0060] In this way, by reasonably setting the distance D4 between the extension center lines of two adjacent first electrically combined units 11 and the distance D2 between the extension center line of the first electrically combined unit 11 located at the outermost side and the end of the adjacent first current collecting grid line 2, as well as the distance D1 between the first electrically combined unit 11 and the second electrically combined unit 12 in each group of electrically combined unit groups 1, the current collection efficiency can be improved, short circuit can be avoided, and the risk of chipping at the edge of the back contact battery can be reduced.

[0061] In some embodiments, the distance between the extension center lines of the two first electrically combined units 11 located at the outermost side and the end of the adjacent first current collecting grid line 2 is D2, the distance between the extension center lines of two adjacent first electrically combined units 11 is D4, and the ratio of D2 to D4 satisfies:

[0062] Wherein, X is the length of the back contact battery in the second direction, and Y is the number of first electrically combined units 11.

[0063] The calculation process of the ratio of D2 to D4 is as follows:

[0064]

[0065] When D2 takes the minimum value and D4 takes the maximum value, the ratio of D2 to D4 is the smallest, and according to 1300 pm < D2 < D4-D1, it is known that the minimum value of D2 is 1300 pm, i.e. 1.3 mm, which is substituted into formula (1) to get the maximum value of D4:

[0066]

[0067] Substituting formula (3) and D2 minimum value of 1.3 mm into formula (2), we get

[0068] For example, the length X of the back contact cell in the second direction can be 156mm-210mm, the number Y of the first electrical combination units can be 12-24, and X and Y are substituted into the formula (4) to obtain the ratio of D2 to D4. For example, when X is 210mm and Y is 12, the ratio of D2 to D4 can be obtained as follows: When X is 210mm and Y is 24, When X is 156mm and Y is 24, When X is 156mm and Y is 12,

[0069] When D2 takes the maximum value and D4 takes the minimum value, the ratio of D2 to D4 is the largest, and according to the above 1300μm<D2≤D4-D1, the maximum value of D2 is D4-D1, so that According to 1300μm<D1<D2, when the minimum value of D1 is 1.3mm, then According to the above, the minimum relationship of the ratio of D2 to D4 can be obtained as follows:

[0070]

[0071] In the case where the length X of the back contact cell in the second direction can be 156mm-210mm and the number Y of the first electrical combination units can be 12-24, the value range of the ratio of D2 to D4 is obtained by substituting the relationship formula (4).

[0072] In the case of the above technical solution, according to the length X of the back contact cell and the number Y of the first electrical combination units 11, the relationship between the distance D2 from the extension center line of the outermost first electrical combination unit 11 to the end of the adjacent first current collecting grid line 2 and the distance D4 between the extension center lines of the adjacent two first electrical combination units 11 is determined, so that the arrangement of the first electrical combination unit 11 on the back contact cell is reasonable, which can improve the current collection efficiency, avoid short circuit and reduce the risk of edge chipping of the back contact cell.

[0073] For example, the length X of the back contact cell in the second direction can be 156mm-210mm, the number Y of the first electrical combination units can be 12-24, and X and Y are substituted into the formula (4) to obtain the ratio of D2 to D4. Figure 1As shown, in some embodiments, in the second direction, the ends of the first and second current collecting grid lines 2 and 3 are flush; the distance from the extension center line of the two outermost first electrically connecting units 11 to the end of the respective adjacent first current collecting grid line 2 is D2; the distance between the extension center lines of the two adjacent first electrically connecting units 11 is D4; the distance between the extension center lines of the two adjacent second electrically connecting units 12 is D5, D4=D5; the distance from the extension center line of the outermost one of the second electrically connecting units 12 to the end of the adjacent second current collecting grid line 3 is D3; the distance from the extension center line of the other outermost one of the second electrically connecting units 12 to the end of the adjacent second current collecting grid line 3 is D6, D3>D6;

[0074] The ratio of D3 to D5 satisfies:

[0075] Wherein, X is the length of the back contact cell in the second direction, and Y is the number of the second electrically connecting units 12.

[0076] The calculation process of the ratio of D3 to D5 is as follows:

[0077] Referring to Figure 1 As shown,

[0078] D3=D1+D2 (5);

[0079]

[0080] Substituting formula (1) and formula (5) into formula (6), we get

[0081]

[0082] From the above embodiments, 2600 μm < D2+D1≤D4, 1300 μm < D2≤D4-D1. It can be seen that when D2+D1 takes the minimum value of 2600 μm and D2 takes the minimum value of 1300 μm, the ratio of D3 to D5 is the smallest, i.e. In addition, D3 cannot exceed D5, therefore, when the ratio of D3 to D5 is the largest, The ratio of D3 to D5 is

[0083] In the case where the length X of the back contact cell in the second direction can be 156 mm to 210 mm and the number Y of the second electrically connecting units can be 12 to 24, substituting relationship (8) gives the value range of the ratio of D3 to D5.

[0084] For example, when X is 210 mm and Y is 12, When X is 210 mm and Y is 24, When X is 156 mm and Y is 24, When X is 156 mm and Y is 12,

[0085] In the above technical solution, according to the length X of the back contact cell and the number Y of the second current collecting units 12, the relationship between the distance D3 from the extension center line of the second current collecting unit 12 located at the outermost side to the end of the adjacent second current collecting grid line 3 and the distance D5 between the extension center lines of the adjacent two second current collecting units 12 is determined, so that the arrangement of the second current collecting unit 12 on the back contact cell is reasonable, and the current collecting efficiency can be improved, short circuit can be avoided, and the risk of fragmentation of the edge of the back contact cell can be reduced.

[0086] As shown in Figure 2 In some embodiments, the first current collecting unit 11 includes a plurality of first current collecting parts 111 arranged at intervals in the first direction, the first current collecting part 111 is connected with the first current collecting grid line 2, and the first current collecting part 111 can be a pad corresponding to the first current collecting grid line 2, an end line close to both ends of the first current collecting grid line 2, or a thickened segment on the first current collecting grid line 2. The second current collecting unit 12 includes a plurality of second current collecting parts 121 arranged at intervals in the first direction, the second current collecting part 121 is connected with the second current collecting grid line 3, and the second current collecting part 121 can be a pad corresponding to the second current collecting grid line 3, an end line close to both ends of the second current collecting grid line 3, or a thickened segment on the second current collecting grid line 3. The first current collecting part 111 and the second current collecting part 121 can be conductively connected with the interconnector such as a solder strip as long as they can be electrically connected with the current collecting grid line.

[0087] In the above technical solution, the first current collecting unit 11 includes a plurality of first current collecting parts 111 arranged at intervals, the first current collecting grid line 2 is connected with the interconnector through the first current collecting part 111, and the second current collecting unit 12 includes a plurality of second current collecting parts 121 arranged at intervals, the second current collecting grid line 3 is connected with the interconnector through the second current collecting part 121. Since the first current collecting unit 11 and the second current collecting unit 12 are both free of main grid, the main grid material is saved and the electrode cost is reduced without affecting the current transmission efficiency.

[0088] In some embodiments, in addition to including a plurality of first current collecting parts 111, the first current collecting unit 11 also includes a first busbar line extending in the first direction, also known as a first main grid, and the first busbar line is connected with the first current collecting part 111.

[0089] Similarly, in addition to including a plurality of second current collecting parts 121, the second current collecting unit 12 also includes a second busbar line extending in the first direction, also known as a second main grid, and the second busbar line is connected with the second current collecting part 121.

[0090] In the technical solution, the first and second electrical connection units 11 and 12 further comprise a main grid, which shortens the current transmission path between the current collection grid lines, further improves the current transmission efficiency, and further collects the carriers in the corresponding area of the back contact cell, and improves the photoelectric conversion efficiency of the cell.

[0091] In a second aspect, the embodiments of the present application further provide a photovoltaic module, comprising a cell string, an interconnection and an encapsulation layer, wherein the cell string is formed by electrically connecting a plurality of back contact cells as described in any of the above embodiments; the interconnection is connected with the electrical connection unit group 1 of the back contact cell; and the encapsulation layer covers the surface of the cell string.

[0092] The beneficial effects of the photovoltaic module in the embodiments of the present application can be referred to the beneficial effect analysis in the first aspect and various implementation manners, which will not be described here.

[0093] In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0094] The above description is merely specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A back contact battery, characterized in that: include: a substrate having opposing first and second sides; a plurality of first collector grid lines and a plurality of second collector grid lines, wherein the first collector grid lines and the second collector grid lines are alternately arranged on the first surface along a first direction, the first collector grid lines and the second collector grid lines extend along a second direction, the first collector grid lines and the second collector grid lines have opposite polarities, and the first direction and the second direction intersect; a plurality of electrical combination unit groups arranged at equal intervals on the first surface along the second direction, each of the electrical combination unit groups including a first electrical combination unit and a second electrical combination unit sequentially arranged at intervals along the second direction, the first electrical combination unit and the second electrical combination unit both extending along the first direction, the first electrical combination unit connected to the first collector grid line, and the second electrical combination unit connected to the second collector grid line; Wherein, in the second direction, the distance between the extended center line of the first electrically combined unit and the extended center line of the second electrically combined unit in a group of the electrically combined unit groups is smaller than the distance between the extended center line of the first electrically combined unit in the group of the electrically combined unit groups and the extended center line of the second electrically combined unit in the adjacent group of the electrically combined unit groups, the width of the first electrically combined unit is M1, the width of the second electrically combined unit is M2, and the distance between the extended center line of the first electrically combined unit and the extended center line of the second electrically combined unit in each group of the electrically combined unit groups is D1.

2. The back contact battery according to claim 1, characterized in that 3. The back contact battery according to claim 1, characterized in that The distance between the extended center line of the first electrical connection unit located at the outermost side of the back contact battery and the end of the adjacent first collector grid line is greater than Alternatively, the distance from the extended center line of the second electrical connection unit located at the outermost side of the back contact battery to the end of the adjacent second collector grid line is greater than 4. The back contact battery according to claim 1, characterized in that A distance D2 from an extended center line of the first electrical connection unit located at the outermost side of the back contact cell to an adjacent end of the first collector grid line satisfies: 1300 μm<D1≤D2.

5. The back contact battery according to claim 1, characterized in that The distance between the extended center lines of two adjacent first electrical combination units is D4, and the distance D2 from the extended center line of the first electrical combination unit located at the outermost side of the back contact battery to the end of the adjacent first collector grid line satisfies: 1300μm<D2≤D4-D1, or, 2600μm<D2+D1≤D4.

6. The back contact battery according to claim 1, characterized in that The distances from the extended center lines of the two outermost first electrical combination units to the ends of the respective adjacent first collector grid lines are both D2, and the distance between the extended center lines of two adjacent first electrical combination units is D4. The ratio of D2 to D4 satisfies: Wherein, X is the length of the back contact battery in the second direction, and Y is the number of the first electrical connection units.

7. The back contact battery according to claim 1, characterized in that In the second direction, ends of the first collector grid line and the second collector grid line are flush; The distances between the extended center lines of the two outermost first electrical combining units and the ends of the first collector grid lines adjacent to each other are both D2; The distance between the extended center lines of two adjacent first electrical combination units is D4; The distance between the extended center lines of two adjacent second electrical combination units is D5, and D4=D5; The distance between the extended center line of the outermost second electrical combination unit and the end of the adjacent second collector grid line is D3; The distance between the extended center line of the other second electrical combination unit located on the outermost side and the end of the adjacent second collector grid line is D6, and D3>D6; The ratio of D3 to D5 satisfies: Wherein, X is the length of the back contact battery in the second direction, and Y is the number of the second electrical combination units.

8. The back contact battery according to claim 1, characterized in that The first electrical connection unit includes a plurality of first electrical connection portions spaced apart along the first direction, wherein the first electrical connection portions are connected to the first collector grid line; And / or, the second electrical combining unit includes a plurality of second electrical combining portions spaced apart along the first direction, and the second electrical combining portions are connected to the second collector grid lines.

9. The back contact battery according to claim 8, characterized in that The first electrical connection unit further includes a first bus bar extending along the first direction, wherein the first bus bar is connected to the first electrical connection portion; And / or, the second electrical combining unit further includes a second bus bar extending along the first direction, and the second bus bar is connected to the second electrical combining portion.

10. A photovoltaic module, characterized in that: include: A battery string, wherein the battery string is formed by electrically connecting a plurality of back-contact batteries according to any one of claims 1 to 9; an interconnection member connected to the electrically coupled unit group of the back contact battery; and an encapsulation layer covering the surface of the battery string.

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