Back contact cell, back contact laminated cell and photovoltaic module

Abstract

The invention relates to a back contact battery, a back contact laminated battery and a photovoltaic module, the back contact battery comprises a battery piece, grid lines with different polarities and an edge bonding pad, the edge of the battery piece along a first direction is provided with an edge connecting line, the battery piece comprises an N-type doped region and a P-type doped region, the grid lines with different polarities are respectively arranged on the N-type doped regions and the P-type doped regions corresponding to the grid lines, the edge bonding pads are bonding pads closest to the edge connecting lines in the first direction, the edge bonding pads are electrically connected with the grid lines with the same polarity, and the edge bonding pads are arranged on the N-type doped regions or the P-type doped regions corresponding to the grid lines with the same polarity. In the first direction, the area, between the edge bonding pad and the edge connecting line close to the edge bonding pad, of the battery piece is the first area, the doped areas in the first area are the doped areas with the same polarity, the grid lines arranged in the first area are the grid lines with the same polarity, the risk that the grid lines are prone to shifting to the doped areas with different polarities in the printing process is reduced, and the printing efficiency is improved. The risk of short circuit is reduced, and the safety of the battery piece is improved.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and particularly to a back-contact battery, a back-contact tandem battery, and a photovoltaic module. Background Art

[0002] A back-contact solar cell is a battery in which an emitter, a surface field, and metal electrodes are all disposed on the back surface (non-light-receiving surface) of the battery. There are no metal electrode blockages on the front surface (light-receiving surface) of the battery, enabling the battery to receive more incident light, reducing optical losses, and improving the photoelectric conversion efficiency. Specifically, first grid lines and second grid lines are generally arranged in a cross pattern on the back surface of the back-contact solar cell. The first grid lines and the second grid lines have different polarities. The first grid lines and the second grid lines are used to connect to doping regions of different polarities respectively and collect the current of their corresponding doping regions. Currently, to reduce the loss of current during transmission, the grid lines are usually widened. However, the widened grid lines have a risk of easily shifting to doping regions of different polarities during printing, resulting in a short-circuit problem in the battery. Summary of the Invention

[0003] The present application provides a back-contact battery, a back-contact tandem battery, and a photovoltaic module to solve the problem that widened grid lines have a risk of easily shifting to doping regions of different polarities during printing to reduce the loss of current during transmission, resulting in a short-circuit problem in the battery.

[0004] In a first aspect of the present application, a back-contact battery is provided. The back-contact battery includes: a battery cell, grid lines of different polarities, and edge pads. An edge connection line is provided along an edge of the battery cell in a first direction. The battery cell includes an N-type doping region and a P-type doping region. The grid lines of different polarities are respectively disposed on the corresponding N-type doping region and P-type doping region. The edge pad is the pad closest to the edge connection line along the first direction. The edge pad is electrically connected to the grid lines of the same polarity, and the edge pad is disposed on the N-type doping region or the P-type doping region corresponding to the grid lines of the same polarity; Along the first direction, a region between the edge pad and the edge connection line adjacent thereto on the battery cell is a first region. The doping regions in the first region are doping regions of the same polarity. One end of each of the grid lines disposed in the first region is electrically connected to the edge connection line, and the other end is electrically connected to the edge pad. Moreover, each of the grid lines disposed in the first region is a grid line of the same polarity.

[0005] In this solution, the doped regions in the first region are all set as doped regions of the same polarity, and the gate lines in the first region are all set as gate lines of the same polarity, so that the gate lines of the same polarity in the first region are all used to collect and transmit the current in the doped regions of the same polarity. Therefore, compared with the traditional back-contact battery with doped regions of different polarities distributed alternately, in this application, the gate lines in the first region can be appropriately widened, that is, the size of the gate lines in the first region along the second direction is appropriately increased. During the subsequent printing of the cell, since there is only one type of doped region in the first region and only one type of gate line of the same polarity in the first region, the risk that the gate lines in the first region are easily offset to the doped regions of different polarities can be greatly reduced, thereby reducing the risk of short circuit in the cell and improving the safety of the cell. At the same time, by setting the gate lines in the first region as gate lines of one polarity and appropriately thickening this part of the gate lines, the series resistance can be effectively reduced, the energy loss during current transmission can be reduced, and thus it is beneficial to improve the photoelectric conversion efficiency of the back-contact battery.

[0006] In this solution, the cell further includes a second region other than the first region. Along the second direction, the N-type doped region and the P-type doped region are alternately arranged in the second region; The sum of the sizes of all the doped regions in the first region along the second direction is W1, and the size of one N-type doped region and / or one P-type doped region in the second region along the second direction is W2, satisfying: 2 ≤ W1 / W2 ≤ 5.

[0007] In this solution, 0.4 mm ≤ W1 ≤ 1 mm is satisfied.

[0008] In this solution, the size D1 of the gate line in the first region along the second direction is greater than the size D2 of the gate line in the second region along the second direction.

[0009] In this solution, when there are three gate lines in the first region, it satisfies: 5 ≤ D1 / D2 ≤ 35; and / or, It satisfies: 0.03 mm ≤ D1 ≤ 0.35 mm.

[0010] In this solution, when there are two gate lines in the first region, it satisfies: 10 ≤ D1 / D2 ≤ 20; and / or, It satisfies: 0.1 mm ≤ D1 ≤ 0.2 mm.

[0011] In this solution, along the second direction, the distance between the two gate lines in the first region is L1, and the distance between the adjacent gate lines in the second region is L2, satisfying: 1 ≤ L1 / L2 ≤ 2.

[0012] In this solution, along the second direction, there is no isolation region between the doped regions located in the first region.

[0013] The second aspect of this application also provides a back-contact stacked cell, which includes a perovskite cell and the back-contact cell described above.

[0014] The third aspect of this application also provides a photovoltaic module, which includes the back-contact cell described above.

[0015] It should be understood that the above general description and the following detailed description are only exemplary and do not limit this application. Description of the Drawings

[0016] Figure 1 It is a schematic diagram of a partial structure of a back-contact cell in the prior art; Figure 2 It is a schematic diagram of a partial structure of the back-contact cell provided by this application in a specific embodiment; Figure 3 It is a schematic diagram of a partial structure of the back-contact cell provided by this application in a specific embodiment; Figure 4 It is Figure 2 A cross-sectional view of a partial structure in a specific embodiment; Figure 5 It is a schematic diagram of a partial structure of the back-contact cell provided by this application in another specific embodiment; Figure 6 It is a schematic diagram of a partial structure of the back-contact cell provided by this application in another specific embodiment; Figure 7 It is Figure 6 A cross-sectional view of a partial structure in a specific embodiment; Figure 8 It is a schematic diagram of the structure of the back-contact stacked cell provided by the embodiment of this application; Figure 9 It is a schematic diagram of the structure of the photovoltaic module provided by the embodiment of this application in an embodiment; Figure 10 It is a schematic diagram of the structure of the photovoltaic module provided by the embodiment of this application in another embodiment.

[0017] Description of the Reference Numerals: 10 - Negative electrode grid line; 20 - Positive electrode grid line; 30 - Pad; 40; Edge connection line; 1 - Back-contact cell; 11 - Cell; 111 - N-type doped region; 112 - P-type doped region; 113 - Substrate; 12 - Edge pad; 13 - Gate line; 131 - First gate line; 132 - Second gate line; 14 - Edge connection line; 15 - Isolation region; 2 - Back - contact stacked cell; 21 - Perovskite cell; 3 - Solder ribbon; 4 - Front plate; 5 - Front encapsulation layer; 6 - Back encapsulation layer; 7 - Backplane.

[0018] The accompanying drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application. Detailed implementation manners

[0019] For a better understanding of the technical solutions of the present application, the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0020] In a specific embodiment, the present application will be further described in detail below through specific embodiments and with reference to the accompanying drawings.

[0021] It should be clear that the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts belong to the scope of protection of the present application.

[0022] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms of "a", "the" and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0023] It should be understood that the term " / " used herein is only a description of the associated relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0024] It should be noted that the orientation terms such as "upper", "lower", "left", and "right" described in the embodiments of the present application are described from the angles shown in the drawings, and should not be construed as limitations on the embodiments of the present application. In addition, in the context, it should also be understood that when it is mentioned that an element is connected "above" or "below" another element, it can not only be directly connected "above" or "below" another element, but also be indirectly connected "above" or "below" another element through an intermediate element.

[0025] Back Contact (BC) solar cells have the emitter, surface field, and metal electrodes all arranged on the back of the cell, with a cross-indicated distribution. The front of the cell uses a SiNx / SiOx double-layer antireflection passivation film, so that there is no metal electrode obstruction on the front of the cell, enabling the cell to receive more incident light, reducing optical losses, and improving the photoelectric conversion efficiency. Specifically, as Figure 1 shown, existing back contact solar cells are provided with alternately distributed P-type doping regions and N-type doping regions, and the back contact solar cells are provided with alternately distributed positive grid lines 20 and negative grid lines 10. The positive grid lines 20 are correspondingly connected to the P-type doping regions, and the negative grid lines 10 are correspondingly connected to the N-type doping regions. The back contact solar cells also include edge connection lines 40 and pads 30, and different polarity grid lines are respectively connected to different pads 30. When sunlight shines on the surface of the back contact solar cell, the photon energy is absorbed by the semiconductor material, generating electron-hole pairs near or on both sides of the p-n junction. Electrons are driven towards the N-type doping region, and holes are driven towards the P-type doping region. Carriers (electrons and holes) can then be collected through the grid lines of their respective different polarities and form a current. Subsequently, the grid lines of different polarities transmit the collected current through the edge connection lines 40 and pads 30 to an external circuit to complete the output of electrical energy. However, currently, in order to reduce the loss of current during transmission, the grid lines are usually widened, but there is often a risk that the widened grid lines are likely to shift to doping regions of different polarities during subsequent printing, resulting in a risk of short circuit in the cell.

[0026] To solve the above problems, the present application provides a back contact cell 1, as Figure 2As shown in the figure, the back contact battery 1 includes a battery cell 11, grid lines 13 of different polarities, and an edge pad 12. An edge connection line 14 is provided along the edge of the battery cell 11 in the first direction X. The battery cell 11 includes a substrate 113, and the substrate 113 is provided with an N-type doping region 111 and a P-type doping region 112. Among them, the grid lines 13 of different polarities are respectively provided on the corresponding N-type doping region 111 and P-type doping region 112. The edge pad 12 is the pad closest to the edge connection line 14 along the first direction X. The edge pad 12 is electrically connected to the grid lines 13 of the same polarity, and the edge pad 12 is provided on the N-type doping region 111 or P-type doping region 112 corresponding to the grid lines 13 of the same polarity.

[0027] Along the first direction X, the region between the edge pad 12 of the battery cell 11 and the edge connection line 14 close to it is the first region. The doping regions in the first region are doping regions of the same polarity. One end of each grid line 13 provided in the first region is electrically connected to the edge connection line 14, and the other end is electrically connected to the edge pad 12. And each grid line 13 provided in the first region is a grid line 13 of the same polarity.

[0028] It should be noted that the first direction X and the second direction Y mentioned in this article can refer to Figure 2 the embodiment shown in the figure. The first direction X intersects with the second direction Y. One of the first direction X and the second direction Y can be the length direction of the back contact battery 1, and the other can be the width direction of the back contact battery 1.

[0029] In this embodiment, by setting the doping regions in the first region to doping regions of the same polarity, and setting the grid lines 13 in the first region to grid lines 13 of the same polarity, so that the grid lines 13 of the same polarity in the first region are all used to collect and transmit the current in the doping regions of the same polarity. Therefore, compared with the traditional back contact battery with alternately distributed doping regions of different polarities, in this application, the grid lines 13 in the first region can be appropriately widened, that is, the size of the grid lines 13 in the first region along the second direction Y is appropriately increased. When the battery cell 11 is printed later, since there is only one type of doped region in the first region and there is also only one type of grid line 13 in the first region, the risk that the grid lines 13 in the first region are easily offset to the doped regions of different polarities can be greatly reduced, thereby reducing the risk of short circuit of the battery cell 11 and improving the safety of the battery cell 11. At the same time, by setting the grid lines 13 in the first region to grid lines 13 of one polarity and appropriately thickening this part of the grid lines 13, the series resistance can be effectively reduced, the energy loss during current transmission can be reduced, and thus it is beneficial to improve the photoelectric conversion efficiency of the back contact battery 1.

[0030] Specifically, as Figure 2As shown, the back contact battery 1 may include a first grid line 131 and a second grid line 132. The polarities of the first grid line 131 and the second grid line 132 are different. The doping region in the first area of the cell 11 may be an N-type doping region 111. The grid line 13 in the first area may be the first grid line 131. The first grid line 131 is disposed on the N-type doping region 111, and the polarity of the first grid line 131 is the same as that of the N-type doping region 111.

[0031] In some other embodiments, as Figure 5 shown, the doping region in the first area of the cell 11 may be a P-type doping region 112. Correspondingly, the grid line 13 in the first area may be the second grid line 132. The polarity of the second grid line 132 is the same as that of the P-type doping region 112.

[0032] The following will be described in detail with the doping region in the first area being the N-type doping region 111 and the grid line 13 in the first area being the first grid line 131.

[0033] When sunlight irradiates the surface of the back contact solar cell, the first grid line 131 collects the current of the N-type doping region 111. The first grid line 131 transmits the current collected by the N-type doping region 111 to the edge connection line 14, and then transmits it from the edge connection line 14 to the pad, and further can output the current to the outside.

[0034] In a possible embodiment, the first grid line 131 in the first area is connected to the edge pad 12 and the edge connection line 14. The first grid line 131 in the first area can be used to collect and transmit the current in the N-type doping region 111 in the first area, and the first grid line 131 in the first area can also transmit the current collected on the other first grid lines 131 that are not connected to the edge pad 12 to the edge pad 12 through the edge connection line 14, so as to achieve output.

[0035] In a possible implementation manner, as Figure 2 and Figure 3 shown, the cell 11 further includes a second area other than the first area. Along the second direction Y, N-type doping regions 111 and P-type doping regions 112 are alternately arranged in the second area.

[0036] Wherein, in a possible implementation, the pads and grid lines 13 arranged and distributed in the second area are the same as those arranged and distributed in the existing back contact battery 1.

[0037] The sum of the sizes of all doping regions in the first area along the second direction Y is W1, and the size of one N-type doping region 111 and / or one P-type doping region 112 in the second area along the second direction Y is W2, satisfying: 2 ≤ W1 / W2 ≤ 5.

[0038] In some embodiments, W1 / W2 can be 2, 2.2, 2.4, 2.5, 2.6, 2.8, 3, 3.2, 3.4, 3.5, 3.6, 3.8, 4, 4.2, 4.4, 4.5, 4.6, 4.8, 5, etc.

[0039] Among them, in one embodiment, as Figure 2 shown, W2 can be the dimension of a P-type doped region 112 in the second region along the second direction Y. In another embodiment, as Figure 3 shown, W2 can be the dimension of an N-type doped region 111 in the second region along the second direction Y. In still another embodiment, when the dimensions of the first gate line 131 and the second gate line 132 in the second region along the second direction Y are the same, W2 can be the dimensions of an N-type doped region 111 and a P-type doped region 112 in the second region along the second direction Y.

[0040] In this embodiment, since the present application appropriately widens the dimension of the first gate line 131 in the first region, that is, along the second direction Y, the dimension of the first gate line 131 in the first region is greater than the dimension of any gate line 13 in the second region, therefore, 2≤W1 / W2≤5 is satisfied, so that the sum of the dimensions of the doped regions in the first region is moderate compared to the dimension of a doped region in the second region. During the subsequent printing process of the battery cell 11, it allows the first gate line 131 located in the first region to have a certain offset error space. Even if there is a slight deviation during the printing process of the first gate line 131, it will not cause the risk of short circuit in the battery, which is beneficial to improving the production qualification rate of the back contact battery 1. At the same time, the sum of the dimensions of the doped regions in the first region is not too small compared to the dimension of a doped region in the second region, so that the number of the first gate lines 131 in the first region is moderate, reducing the risk of limited current output caused by insufficient electrode coverage, improving the effective collection performance of carriers, increasing the current density, and at the same time enabling the battery cell 11 to have good structural strength, reducing the risk of hidden cracks, and improving the service life.

[0041] In a possible implementation manner, as Figure 2 shown, 0.4mm≤W1≤1mm is satisfied. In some embodiments, W1 can be 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, etc.

[0042] In this embodiment, 0.4 mm ≤ W1 ≤ 1 mm is satisfied, so that the sum of the sizes of the doped regions in the first region is moderate, so that the distance for the photo-generated carriers generated by the N-type doped region 111 in the first region to reach the electrode is moderate, so that the transmission distance is moderate, reducing the risk of excessive recombination loss. At the same time, the spacing size between adjacent gate lines 13 in the first region is moderate, so that the lateral resistance is moderate, reducing energy loss, which is beneficial to improving the open-circuit voltage and fill factor of the back-contact battery 1 and improving the photoelectric conversion efficiency.

[0043] In a possible implementation manner, as Figures 2 - 4 、 Figure 6 and Figure 7 shown, the size D1 of the gate line 13 in the first region along the second direction Y is greater than the size D2 of the gate line 13 in the second region along the second direction Y.

[0044] In this embodiment, the size D1 of the first gate line 131 in the first region along the second direction Y is greater than the size D2 of the first gate line 131 and / or the second gate line 132 in the second region along the second direction Y. That is, the size of the first gate line 131 in the first region along the second direction Y can be appropriately increased, which can effectively reduce the series resistance in the first region, reduce the energy loss during current transmission in the first region, improve the current collection efficiency, and thus is beneficial to improving the photoelectric conversion efficiency of the back-contact battery 1. At the same time, the first gate line 131 in the first region is electrically connected to the edge pad 12, and the edge pad 12 is subsequently welded to the solder tape 3, so that the width size of the first gate line 131 in the first region can be appropriately increased, which is beneficial to improving the structural strength of the first gate line 131 in this region, beneficial to improving the welding strength between the subsequent cell 11 and the solder tape 3, improving the welding reliability and stability, and improving the working reliability and stability of the back-contact battery 1.

[0045] In a possible implementation manner, as Figure 2 and Figure 4 shown, when there are three gate lines 13 in the first region, 5 ≤ D1 / D2 ≤ 35 is satisfied. In some embodiments, D1 / D2 can be 5, 6, 8, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, 32, 34, 35, etc.

[0046] Therefore, the condition: 5≤D1 / D2≤35 is satisfied, so that the size of the first gate line 131 in the first region relative to the gate line 13 in the second region along the second direction Y is moderate, the size of the first gate line 131 in the first region along the second direction Y is not too large, the area of the gate line 13 in the first region blocking the incident light is not too large, so that the battery cell 11 still has a good effective light absorption area, and at the same time, the size of the first gate line 131 in the first region along the second direction Y is not too small. Since the gate line 13 in the first region is connected to the edge pad 12, appropriately widening the width of the gate line 13 in this region can be beneficial to dispersing the current density, so that the current density transmitted in the first region is moderate, and the local temperature in the first region is not too high, thereby reducing the risk of forming a hot spot effect and improving the service life of the back contact battery 1.

[0047] In a possible implementation, Figure 4 As shown, when three gate lines 13 are arranged in the first region, 0.03 mm ≤ D1 ≤ 0.35 mm is satisfied. In some embodiments, D1 may be 0.03 mm, 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, etc.

[0048] Therefore, when three grid lines 13 are arranged in the first area, the following is satisfied: 0.03mm≤D1≤0.35mm, so that the size of the grid lines 13 in the first area along the second direction Y is moderate, effectively balancing the effective area and conductivity of the battery absorbing light, and at the same time making the structural strength of the first grid lines 131 in the area moderate, reducing the risk of hidden cracks or breakage of the grid lines 13 during subsequent assembly.

[0049] In summary, when there are three gate lines 13 in the first region, the following conditions are satisfied: 5≤D1 / D2≤35, and / or 5≤D1 / D2≤35, which effectively balances the effective area and conductivity of the cell for absorbing light, improves the photoelectric conversion efficiency of the back-contact cell 1, and facilitates subsequent assembly and production. At the same time, three gate lines 13 are arranged in the first region, and three gate lines 13 are also distributed along the second direction Y on the side of the edge pad 12 that is away from the first region along the first direction X, which is conducive to balancing the current density distribution, so that the local current density distribution of the back-contact cell 1 will not be too high.

[0050] In another possible implementation, Figure 6 and Figure 7As shown, when two gate lines 13 are provided in the first region, the following conditions are satisfied: 10 ≤ D1 / D2 ≤ 20. Among them, D1 / D2 can be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, etc.; and / or, the following condition is satisfied: 0.1 mm ≤ D1 ≤ 0.2 mm, where D1 can be 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, etc.

[0051] Therefore, when two gate lines 13 are provided in the first region, 10 ≤ D1 / D2 ≤ 20 is satisfied, so that the size of the first gate line 131 in the first region relative to the gate line 13 in the second region increasing along the second direction Y is appropriate, the size of the first gate line 131 in the first region along the second direction Y will not be too large, and the first gate line 131 in the first region will not block too much incident light, so that the solar cell 11 still has a good effective light absorption area. At the same time, the risk of heat accumulation is reduced.

[0052] Therefore, when two gate lines 13 are provided in the first region, 0.1 mm ≤ D1 ≤ 0.2 mm, so that the size of the gate line 13 in the first region along the second direction Y is appropriate, which is beneficial to enhancing the current-carrying capacity of the back-contact battery 1. At the same time, the structural strength of the first gate line 131 in this region is appropriate, reducing the risk of breakage during subsequent assembly.

[0053] In summary, when two gate lines 13 are provided in the first region, 10 ≤ D1 / D2 ≤ 20 is satisfied and / or 0.1 mm ≤ D1 ≤ 0.2 mm is satisfied, so that the size of the gate line 13 in the first region along the second direction Y is appropriate, which is beneficial to further reducing the series resistance and enhancing the current-carrying capacity at the same time. In addition, providing two gate lines 13 in the first region facilitates subsequent printing, which is beneficial to improving the production efficiency and delivery qualification rate of the back-contact battery 1.

[0054] In a possible implementation manner, as Figure 6 shown, along the second direction Y, the distance between the two gate lines 13 in the first region is L1, and the distance between adjacent gate lines 13 in the second region is L2, satisfying: 1 ≤ L1 / L2 ≤ 2. In some embodiments, L1 / L2 can be 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, etc.

[0055] In this embodiment, when two gate lines 13 are provided in the first region, the following conditions are satisfied: 1 ≤ L1 / L2 ≤ 2. Since the first gate line 131 in the first region is connected to the edge pad 12, the current density transmitted in the first region is made moderate, reducing the risk of excessive current in the first region, preventing the local temperature in the first region from being too high, reducing the risk of forming a hot spot effect, and increasing the service life of the back contact battery 1. At the same time, satisfying 1 ≤ L1 / L2 ≤ 2 makes the area of the cell 11 not blocked in the first region moderate, effectively balancing the effective area of light absorption by the battery and its conductivity, that is, balancing the light absorption efficiency and the efficiency of the gate line 13 in collecting current in this region, so that the back contact battery 1 operates with good efficiency.

[0056] In a possible implementation manner, as Figure 4 and Figure 7 shown, along the second direction Y, there is no isolation region 15, that is, no GAP region, between the doped regions located in the first region, and an isolation region 15 is provided between the N-type doped regions 111 and P-type doped regions 112 distributed alternately in the second region.

[0057] Compared with the traditional back contact battery where an isolation region is provided between the alternately arranged N-type and P-type doped regions, in this embodiment, there is no isolation region 15 between the doped regions located in the first region, which enables carriers to reach the corresponding electrodes more directly, is beneficial to reducing the transmission distance, improving the current collection efficiency, and can improve the space utilization rate of the cell 11 and the effective area of light absorption, further improving the conversion efficiency. In addition, an isolation region 15 is provided between the N-type doped regions 111 and P-type doped regions 112 distributed alternately in the second region, which is beneficial to reducing the unnecessary recombination of electrons and holes between the N-type doped regions 111 and P-type doped regions 112 and improving the photoelectric conversion efficiency.

[0058] Among them, the doped regions in the first region can be integrally formed, which is convenient for processing and production and improves production efficiency.

[0059] In some embodiments, the type of the back contact battery 1 in the present application can be one of an interdigitated back contact battery (IBC), a heterojunction back contact battery (HBC), and a tunnel oxide back contact battery (TBC).

[0060] For an IBC cell, along its thickness direction, the IBC cell sequentially includes a silicon nitride back layer, an N+ front surface field, an N-type substrate silicon layer, a P+ emitter, an N+ back field, an aluminum oxide passivation layer, a silicon nitride antireflection layer, and a metal silver electrode. The IBC cell uses ion implantation technology to obtain P and N regions with good uniformity and precisely controllable junction depth. There are no grid lines blocking on the front side of the cell, which can eliminate the shading current loss of the metal electrode and maximize the utilization of incident photons. The short-circuit current can be increased by about 7% compared with conventional solar cells. Due to the back contact structure, there is no need to consider the problem of grid line blockage, and the grid line ratio can be appropriately widened, thereby reducing the series resistance and having a high fill factor. The surface passivation and surface light trapping structure can be optimized, and a lower front surface recombination rate and surface reflection can be obtained.

[0061] For an HBC cell, the HBC cell combines the advantages of IBC cells and heterojunction cells well. Its front surface passivation layer uses hydrogenated amorphous silicon, and N-type and P-type amorphous silicon thin films are respectively deposited on the back to form a heterojunction. The HBC cell makes full use of the excellent surface passivation performance of amorphous silicon, and the heterojunction structure formed on the back has a good passivation effect, which can simultaneously achieve higher short-circuit current and open-circuit voltage, thereby improving the photoelectric conversion efficiency.

[0062] For a TBC cell, the TBC cell combines the advantages of the tunneling oxide layer technology of Topcon and the back-arranged electrodes of IBC. The passivation effect and open-circuit voltage are significantly improved, and it can be economical while achieving a higher cell conversion efficiency. The complete production process of the TBC cell mainly includes depositing a tunneling oxide layer and P+ polysilicon, depositing a passivation film, printing electrodes on the back of the silicon wafer, etc. The TBC cell needs to add related processes for the back electrodes such as masking, laser grooving, PN region preparation, and etching on the basis of the TOPCon production process. The masking is mainly completed by APCVD or PECVD, the preparation of the PN region is mainly completed by PECVD, the etching mainly uses traditional wet equipment, and the grooving process needs to be completed by a laser device.

[0063] This application also provides a back-contact stacked cell 2, as Figure 8As shown in the figure, the back-contact stacked cell 2 includes a perovskite cell 21 and the back-contact cell 1 in any of the above embodiments. Along the thickness direction Z of the back-contact stacked cell 2, the perovskite cell 21 and the light-facing surface of the back-contact cell 1 are electrically connected. The perovskite cell 21 is a thin-film solar cell with a perovskite material as the photoactive layer. The structure of the perovskite cell 21 mainly consists of the following key components: a transparent conductive substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode. These components work together to enable the perovskite cell 21 to effectively absorb sunlight and convert it into electrical energy. The perovskite material in the perovskite light-absorbing layer has excellent light absorption properties, can absorb a wider spectral range, and effectively convert short-wavelength spectra, making the perovskite cell 21 have a high photoelectric conversion efficiency.

[0064] This application also provides a photovoltaic module, as Figure 9 shown, the photovoltaic module includes the back-contact cell 1 in any of the above embodiments, or, as Figure 10 shown, the photovoltaic module includes the back-contact stacked cell 2 in any of the above embodiments.

[0065] Specifically, a photovoltaic system includes a battery assembly. The battery assembly includes a plurality of battery strings. The battery strings include the back-contact cell 1 or the back-contact stacked cell 2 in any of the above embodiments. The back-contact cells 1 or the back-contact stacked cells 2 in the battery assembly can be sequentially connected in series through welding strips 3 to form a battery string. Each battery string in the battery assembly can be connected in series, in parallel, or in a series-parallel combination through busbars to achieve current collection and output.

[0066] As Figure 9 and Figure 10 shown, the photovoltaic module further includes a front plate 4, a front encapsulation layer 5, a back encapsulation layer 6, and a back plate 7. The front plate 4 and the back plate 7 jointly hold the front encapsulation layer 5, the photovoltaic cell, the welding strip 3, and the back encapsulation layer 6, and form a photovoltaic module through lamination encapsulation. Among them, the front encapsulation layer 5 is used to protect the light-facing surface of the photovoltaic cell, and the back encapsulation layer 6 is used to protect the backlight surface of the photovoltaic cell. At the same time, during the lamination process of the photovoltaic module, the front encapsulation layer 5 and the back encapsulation layer 6 are used to encapsulate and protect the photovoltaic cell and the welding strip 3, prevent the external environment from affecting the performance of the photovoltaic cell and the welding strip 3, and at the same time can bond the front plate 4, the back plate 7, the photovoltaic cell, and the welding strip 3 into a whole. Among them, the photovoltaic cell is the back-contact cell 1 or the back-contact stacked cell 2 in any of the above embodiments.

[0067] Among them, the materials of the front plate 4 and the back plate 7 can be one of rigid materials such as tempered glass, polyethylene terephthalate (PET), polycarbonate (PC), etc. or one of flexible materials such as polyvinyl fluoride (PVF), ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), etc. The front encapsulation and the back encapsulation layer 6 are adhesive films, and the materials of the adhesive films can be one of materials such as ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), polyvinyl butyral (PVB), etc. The front encapsulation layer 5 and the back encapsulation layer 6 can also be EPE adhesive films (EVA-POE-EVA co-extrusion structure) or EP adhesive films (EVA-EP co-extrusion structure).

[0068] The above is only the specific implementation manner of the embodiments of the present application, but the protection scope of the embodiments of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the embodiments of the present application should be covered within the protection scope of the embodiments of the present application. Therefore, the protection scope of the embodiments of the present application should be subject to the protection scope of the claims.

Claims

1. A back-contact battery, characterized in that, The back-contact battery (1) includes: A cell (11), an edge connection line (14) is provided along the edge of the cell (11) in the first direction (X), and the cell (11) includes an N-type doped region (111) and a P-type doped region (112); Grid lines (13) of different polarities, the grid lines (13) of different polarities are respectively provided on the corresponding N-type doped region (111) and the P-type doped region (112); An edge pad (12), the edge pad (12) is the pad closest to the edge connection line (14) along the first direction (X), the edge pad (12) is electrically connected to the grid lines (13) of the same polarity, and the edge pad (12) is provided on the N-type doped region (111) or the P-type doped region (112) corresponding to the grid lines (13) of the same polarity; Along the first direction (X), the region between the edge pad (12) of the cell (11) and the edge connection line (14) close to it is the first region, the doped regions in the first region are doped regions of the same polarity, one end of each of the grid lines (13) provided in the first region is electrically connected to the edge connection line (14), the other end is electrically connected to the edge pad (12), and each of the grid lines (13) provided in the first region is the grid line (13) of the same polarity.

2. The back contact battery according to claim 1, wherein, The cell (11) further includes a second region other than the first region, along the second direction (Y), the N-type doped region (111) and the P-type doped region (112) are alternately provided in the second region; The sum of the sizes of all doped regions in the first region along the second direction (Y) is W1, the size of one N-type doped region (111) and / or one P-type doped region (112) in the second region along the second direction (Y) is W2, and it satisfies: 2 ≤ W1 / W2 ≤ 5.

3. The back-contact battery according to claim 2, wherein It satisfies 0.4mm ≤ W1 ≤ 1mm.

4. The back contact battery according to claim 2, wherein, The size D1 of the grid line (13) in the first region along the second direction (Y) is greater than the size D2 of the grid line (13) in the second region along the second direction (Y).

5. The back-contact battery according to claim 4, characterized in that, When three grid lines (13) are provided in the first region, it satisfies: 5 ≤ D1 / D2 ≤ 35; and / or, It satisfies: 0.03mm ≤ D1 ≤ 0.35mm.

6. The back-contact battery according to claim 4, wherein When two grid lines (13) are provided in the first region, it satisfies: 10 ≤ D1 / D2 ≤ 20; and / or, It satisfies: 0.1mm ≤ D1 ≤ 0.2mm.

7. The back contact battery according to claim 6, characterized in that, Along the second direction (Y), the distance between the two grid lines (13) in the first region is L1, and the distance between adjacent grid lines (13) in the second region is L2, and it satisfies: 1 ≤ L1 / L2 ≤ 2.

8. The back contact battery according to any one of claims 1-7, characterized in that, Along the second direction (Y), there is no isolation region between the doped regions in the first region.

9. A back-contact stacked cell, characterized in that, The back-contact stacked battery (2) includes a perovskite battery (21) and the back-contact battery (1) according to any one of claims 1-8.

10. A photovoltaic module, characterized in that, The photovoltaic module includes the back-contact cell (1) described in any one of claims 1-8, or the photovoltaic module includes the back-contact tandem cell (2) described in claim 9.

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