Back contact cell and photovoltaic module

Abstract

The application discloses a back contact cell and a photovoltaic module. The back contact cell comprises a cell body, a first surface and a second surface oppositely arranged, the first surface comprises a first area close to a first edge, a plurality of first fine grids and a plurality of second fine grids are arranged on the first surface and are alternately distributed along a first direction and extend along a second direction, a first end conductive member is arranged on the first area and extends along the first direction and is connected with at least two first fine grids, and the second fine grids are interrupted at the first end conductive member. At least one first end conductive member has a first voltage test point. In the IV or EL test process, a test probe used in the IV or EL test is electrically connected with the first voltage test point, the first voltage test point can stably contact with the test probe, a stable electrical connection is formed between the test probe and the first voltage test point, and therefore, the test difficulty is reduced, and the reliability and stability of the IV or EL test are improved.

Description

TECHNICAL FIELD

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

[0002] The back contact cell refers to a solar cell in which no electrode is arranged on the light-receiving surface of a cell, and the positive and negative electrodes are arranged on the back surface of the cell, so that the shading of the electrodes on the cell can be reduced, the short-circuit current of the cell can be increased, and the energy conversion efficiency of the cell can be improved.

[0003] In order to reduce the use of paste and reduce the risk of short circuit, some back contact solar cells adopt a design without main grids. However, on the one hand, in such a technical solution, the difficulty of performing IV, EL (Electro Luminescence) and other performance tests on the back contact solar cell is greatly increased, the back contact solar cell and the test probe cannot be stably contacted, the test is difficult, and the reliability and stability are poor. SUMMARY

[0004] The purpose of the present application is to provide a back contact cell and a photovoltaic module to reduce the test difficulty and improve the reliability and stability of the test.

[0005] In order to achieve the above purpose, the present application provides the following technical solution:

[0006] A back contact cell comprises:

[0007] A cell body comprising a first surface and a second surface arranged oppositely, the first surface comprising a first edge and a second edge arranged oppositely along a first direction and a third edge and a fourth edge arranged oppositely along a second direction; the first surface further comprising a first region close to the first edge;

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

[0009] A first end conductive member is arranged on the first region and extends along the first direction, and is connected to at least two first fine grids, and the second fine grids are interrupted at the first end conductive member;

[0010] The first end conductive member has a first voltage test point.

[0011] The back contact battery provided in the application has a first voltage test point on at least one first end conductive member. The first voltage test point can be any component matched with a test probe or a region matched with a test probe. For example, the first voltage test point can be an open voltage needle. In the IV or EL test process, the test probe used in the IV or EL test is electrically connected with the first voltage test point. The first voltage test point can stably contact with the test probe, so that a stable electrical connection is formed between the test probe and the first voltage test point, thereby reducing the test difficulty and improving the reliability and stability of the IV or EL test.

[0012] In an implementation manner, the width of the first voltage test point along the second direction is greater than the width of the first end conductive member along the second direction. In this way, the width of the first voltage test point along the second direction is widened, which is beneficial to providing the contact area of the first voltage test point with the test probe and further ensuring that a stable electrical connection is formed between the test probe and the first voltage test point.

[0013] In an implementation manner, the first voltage test point is arranged at the intersection position of the first fine grid and the first end conductive member. In this way, along the second direction, the first voltage test point is arranged in alignment with one first fine grid, and the current of the first fine grid can flow to the first voltage test point along the shortest distance, thereby shortening the current flow distance and reducing the current loss, and further improving the reliability and stability of the test.

[0014] In an implementation manner, the first end conductive member includes a first end portion away from the first side;

[0015] The distance between the first voltage test point and the first end portion is S1, the length of the first end conductive member along the first direction is L1, and S1 / L1 is less than or equal to 0.5. In this way, the extension distance of the first voltage test point along the first direction can be prevented from being too long, so that the transmission resistance of the first voltage test point is not too large, and the accuracy of the test is affected. At the same time, when string welding, the end of the electrical connector (welding strip) can also reach the first voltage test point due to errors, and the fine grid can be protected from being broken by welding, so the first voltage test point needs to be slightly close to the first pad.

[0016] In an implementation manner, the first end conductive member includes a first end portion away from the first side; the back contact battery further includes a first pad arranged at the first region, the first pad is electrically connected with the first end portion of the first end conductive member, and the first pad is connected with at least one first fine grid. In this way, the current of the first fine grid connected with the first pad can directly flow to the first pad, so that the current of the first fine grid connected with the first pad can flow to the first pad along the shortest distance, thereby shortening the current flow distance and reducing the current loss, and further improving the reliability and stability of the test.

[0017] In an implementation manner, the first voltage test point has the same width as the first pad in the second direction. With the technical solution, the first voltage test point can be arranged in alignment with the first pad, the first fine grid aligned with the first voltage test point and the first fine grid connected with the first pad have the same length, the current distribution is more uniform, and thus the current loss is reduced.

[0018] In an implementation manner, in the first region, the battery body includes a plurality of stacked portions, the plurality of stacked portions are arranged in sequence in the first direction, and each stacked portion includes a first doped layer and a second doped layer arranged in sequence, and the first voltage test point is arranged on one of the stacked portions. Since the height of the stacked portion is high, the first voltage test point is arranged on the stacked portion, the first voltage test point is more easily identified in the testing process, and the testing efficiency is improved.

[0019] In an implementation manner, the battery body further includes a second region adjacent to the first region and away from the first region, a plurality of second pads are arranged on the second region, the plurality of second pads are electrically connected with the first fine grids in the second region and arranged in sequence in the first direction.

[0020] In the second direction, the width of the first voltage test point, the width of the first pad, and the width of the second pad are equal, so that the lengths of the first fine grids connected with the first voltage test point, the first fine grids connected with the first pad, and the first fine grids connected with the second pad are equal, the current distribution is more uniform, and thus the current loss is reduced.

[0021] In the first direction, the extension distance of the first voltage test point and the extension distance of the second pad are both less than the extension distance of the first pad. In the technical solution, the extension distance of the first pad in the first direction is greater than the extension distance of the second pad and the first voltage test point in the first direction, so that the conductive volume of the first pad is increased, the transmission resistance of the first pad is reduced, the current loss is reduced, and the power generation efficiency of the back contact battery is improved.

[0022] In an implementation manner, the battery body further includes a second end conductive member arranged in the first region and extending in the first direction, the second end conductive member and the first end conductive member are arranged in sequence and alternately in the second direction, at least one second end conductive member is provided with a second voltage test point, and the second voltage test point and the first voltage test point on the adjacent second end conductive member and the first end conductive member are arranged staggered in the first direction. With the technical solution, in the first direction, the first voltage test point can be aligned with the first fine grid, and the second voltage test point can be aligned with the second fine grid, so that the current in the first fine grid aligned with the first voltage test point and the second fine grid aligned with the second voltage test point can flow to the voltage test point through the shortest distance, and the current loss is further reduced.

[0023] In an implementation, the first region is evenly divided into two parts along the second direction, and at least one first end conductive member and at least one second end conductive member in each part have voltage test points thereon; and / or,

[0024] The back surface of the back contact cell includes two first regions and a second region between the two first regions, any first region is evenly divided into two parts along the second direction, and at least one first end conductive member and at least one second end conductive member in each part have voltage test points thereon. With this technical solution, the first voltage test points and the second voltage test points are more evenly distributed in the first region, avoiding test errors caused by uneven regions, and further improving the accuracy of back contact cell testing.

[0025] In an implementation, among the first end conductive member and the second end conductive member adjacent along the second direction, the first voltage test point on the first end conductive member is electrically connected to a first fine grid, and the second voltage test point on the second end conductive member is electrically connected to a second fine grid, and the first fine grid electrically connected to the first voltage test point and the second fine grid electrically connected to the second voltage test point are arranged adjacent along the first direction. In this way, the distance between the first voltage test point and the second voltage test point on the adjacent first end conductive member and second end conductive member is smaller, and the test accuracy is higher.

[0026] In an implementation, along the first direction, the difference between the extension distances of the first end conductive member and the second end conductive member is the spacing between the adjacent first fine grid and the second fine grid. In this way, the arrangement positions of the first end conductive member and the second end conductive member along the first direction are roughly aligned, the current flowing through the first end conductive member and the second end conductive member is roughly the same, the situation of local current being too large and temperature being too high is avoided, and the stability of the performance of the entire back contact cell is ensured.

[0027] In an implementation, the first end conductive member is electrically connected to at least 5 first fine grids. In the case of electrically conductive connection between the electrical connecting member and the first end conductive member, the electrical connecting member does not have to extend to the vicinity of the first edge, the distance between the end of the electrical connecting member and the first edge is larger, and the situation of the electrical connecting member extending to the vicinity of the first edge easily shaking and mispositioning, leading to electric leakage, is avoided.

[0028] In an implementation, the first end conductive member gradually decreases in width along the second direction in a direction close to the first side. It can be understood that the current flowing through the first end conductive member or the second end conductive member gradually increases along the direction close to the second region, and therefore the width of the first end conductive member or the second end conductive member gradually increases along the direction close to the second region in the technical solution, so as to gradually reduce the transmission resistance of the first end conductive member or the second end conductive member, and the transmission resistance of the first end conductive member or the second end conductive member is adapted to the current flowing through the first end conductive member or the second end conductive member, thereby further reducing the current loss and improving the efficiency of the solar cell.

[0029] A photovoltaic module comprising the back contact cell and the electrical connector according to any one of the above embodiments.

[0030] Compared with the prior art, the photovoltaic module provided in the present application has the same beneficial effects as the back contact cell described above, which will not be repeated here.

[0031] In an implementation, the first end conductive member comprises a first end portion away from the first side; the back contact cell further comprises a first pad arranged at the first region, the first pad being electrically connected to the first end portion of the first end conductive member and arranged close to the boundary between the first region and the second region.

[0032] In the first direction, the end portion of the electrical connector is located between the first pad and the first voltage test point. In this way, the electrical connector can be ensured to be in good electrical connection with the first pad, and the electrical connector can also be prevented from affecting the cooperation between the first voltage test point and the test probe. BRIEF DESCRIPTION OF DRAWINGS

[0033] The accompanying drawings, which are included to provide a further understanding of the present application and constitute a part of this application, illustrate embodiments of the present application and together with the description serve to explain the present application. In the drawings:

[0034] Figure 1 A schematic diagram of the back contact cell according to an embodiment of the present application;

[0035] Figure 2 A schematic diagram of the back contact cell according to another embodiment of the present application;

[0036] Figure 3 A schematic diagram of the back contact cell according to another embodiment of the present application.

[0037] Reference Signs:

[0038] 1 - first voltage test point, 2 - first end conductive member, 3 - first pad, 4 - second end conductive member, 5 - second fine grid, 6 - first fine grid, 7 - second voltage test point, 8 - second pad, 9 - first interface layer, 10 - first doped layer, 11 - second doped layer, 12 - second interface layer, 13 - semiconductor substrate;

[0039] A - first region, B - second region. DETAILED DESCRIPTION

[0040] In order to make the technical problems to be solved, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, and not to limit the present application.

[0041] It should be noted that when an element is referred to as being "fixed to" or "set 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.

[0042] In addition, the terms "first", "second" are only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. 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 specified. The meaning of "several" is one or more, unless otherwise explicitly specified.

[0043] 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 shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0044] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" 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.

[0045] As described in the background, the front side of the back contact solar cell has no grid lines, completely avoiding the efficiency loss caused by the shading effect of the grid lines; however, since the P / N junction is on the back side, compared with the conventional cell, it needs to set double the number of main grids on the back side for current collection, and in order to reduce the risk of short circuit, the main grid needs to be broken by a fine grid with opposite polarity. Therefore, the existence of the main grid limits the space for cost reduction and efficiency improvement.

[0046] In order to balance efficiency and cost, some manufacturers cancel the main grid design of the back contact cell, and only keep the welding pad point at the fixed position of the fine grid, and the P / N fine grid is designed as a completely penetrating type of plug-in design, so as to achieve better cost and performance. However, when performing IV and EL tests in the past, the test probe is often electrically connected with the main grid for testing. The IV test is responsible for collecting cell performance data, mainly by using the current needle and voltage needle to collect the corresponding IV data after the cell is excited by irradiation, and calculating the performance; the EL test is responsible for testing the defects of the cell, mainly by using the current needle to excite the fluorescent effect of the cell to collect the performance picture of the cell. After the main grid design of the back contact cell is cancelled, the test probe cannot stably contact with the fine grid, and the test is difficult, and the reliability and stability are poor.

[0047] In view of the above situation, the back contact cell provided by the present application is provided to facilitate the electrical connection between the test probe and the fine grid, and to reduce the test difficulty.

[0048] Please refer to Figure 1 The back contact cell provided by the embodiment of the present application includes a cell body, a first fine grid 6, a second fine grid 5, a first end conductive member 2, and a first voltage test point 1. The cell body includes a first surface and a second surface arranged opposite to each other. Specifically, the first surface and the second surface are arranged opposite to each other along the thickness direction of the cell body. The first surface has a first edge and a second edge arranged opposite to each other along a first direction, i.e., the first edge and the second edge are arranged in sequence along the first direction, and the first edge and the second edge can be arranged perpendicular to the first direction. The first surface has a third edge and a fourth edge arranged opposite to each other along a second direction, i.e., the third edge and the fourth edge are arranged in sequence along the second direction, and the third edge and the fourth edge can be arranged perpendicular to the second direction. The two ends of the first edge are connected with the third edge and the fourth edge respectively, and the two ends of the second edge are connected with the third edge and the fourth edge respectively.

[0049] The first surface further includes a first area A close to the first edge, i.e., the first area A is arranged close to the first edge.

[0050] Specifically, the battery body includes a semiconductor substrate 13, a first doped layer 10, and a second doped layer 11. The first doped layer 10 and the second doped layer 11 are oppositely doped to collect and extract electrons and holes, respectively, to facilitate the formation of photocurrent. The first doped layer 10 and the second doped layer 11 are arranged on the first surface of the semiconductor substrate 13 and are alternately distributed along the first direction. Specifically, the first doped layer 10 and the second doped layer 11 can be alternately and spacedly distributed in a strip shape or in an interdigital shape. The first doped layer 10 and the second doped layer 11 have an isolation region therebetween to reduce the carrier recombination rate at the lateral junction of the first doped layer 10 and the second doped layer 11, thereby facilitating the improvement of the photoelectric conversion efficiency of the back contact battery.

[0051] The number of the first fine grids 6 and the second fine grids 5 is multiple. The multiple first fine grids 6 and the multiple second fine grids 5 are arranged on the first surface and are alternately distributed along the first direction. The multiple first fine grids 6 and the multiple second fine grids 5 extend along the second direction. The first fine grids 6 and the second fine grids 5 are of different polarities. Specifically, the first fine grids 6 are arranged on the first doped layer 10 to extract the carriers collected by the first doped layer 10 by using the first fine grids 6. The second fine grids 5 are arranged on the second doped layer 11 to extract the carriers collected by the second doped layer 11 by using the second fine grids 5.

[0052] The first direction intersects the second direction, i.e., the first direction is different from the second direction. The included angle between the first direction and the second direction can be an acute angle or a right angle. For example, the first direction is arranged parallel to the third edge and the fourth edge, and the second direction is arranged parallel to the first edge and the second edge.

[0053] The first end conductive member 2 is arranged on the first region A and extends along the first direction, i.e., the length direction of the first end conductive member 2 extends along the first direction. The first end conductive member 2 is connected to at least two first fine grids 6. Specifically, the multiple first fine grids 6 adjacent along the first direction are all electrically connected to the first end conductive member 2, so that the current of the multiple first fine grids 6 adjacent to each other is converged by using the first end conductive member 2. Further, the multiple first fine grids 6 adjacent to each other and close to the first edge are all electrically connected to the first end conductive member 2, i.e., along the direction from the first edge to the second edge, the current of the multiple first fine grids 6 adjacent to each other and close to the first edge is extracted to the electrical connecting member (which can be a solder strip or a main grid) by the first end conductive member 2. In this way, the electrical connecting member is electrically connected to the first end conductive member 2, and the electrical connecting member does not have to extend to the vicinity of the first edge, thereby avoiding the situation that the electrical connecting member extending to the vicinity of the first edge is prone to shaking and mispositioning, resulting in electric leakage. In addition, the second fine grids 5 are interrupted at the first end conductive member 2, preventing the first end conductive member 2 from contacting the second fine grids 5, and avoiding the risk of electric leakage.

[0054] In addition, at least one first end conductive member 2 has a first voltage test point 1. The first voltage test point 1 can be any component that cooperates with the test probe or an area that cooperates with the test probe. For example, the first voltage test point 1 can be an opening pin. In this way, during the IV or EL test, the test probe used in the IV or EL test is electrically connected to the first voltage test point 1, and the first voltage test point 1 and the test probe can make stable contact, so that a stable electrical connection is formed between the test probe and the first voltage test point 1, thereby reducing the test difficulty and improving the reliability and stability of the IV or EL test.

[0055] In some embodiments, such as Figure 1 As shown, the width of the first voltage test point 1 along the second direction is greater than the width of the first end conductive member 2 along the second direction. In other words, along the second direction, the two side edges of the first voltage test point 1 extend beyond the two side edges of the first end conductive member 2. This arrangement widens the width of the first voltage test point 1 along the second direction, which is beneficial for providing the contact area between the first voltage test point 1 and the test probe, further ensuring a stable electrical connection between the test probe and the first voltage test point 1.

[0056] In other embodiments, such as Figure 1 As shown, the first voltage test point 1 is located at the intersection of the first fine grid 6 and the first end conductive element 2. Using this technical solution, along the second direction, the first voltage test point 1 is aligned with one of the first fine grids 6. The current in the first fine grid 6 can flow to the first voltage test point 1 along the shortest distance, shortening the current flow distance, thereby reducing current loss and further improving the reliability and stability of the test.

[0057] In some embodiments, such as Figure 1 As shown, the first end conductive element 2 includes a first end far from the first side, i.e., along the first direction, the two ends of the first end conductive element 2 are the first end and the second end, respectively. The first end is closer to the second side than the second end, and the second end is closer to the first side than the first end. The distance between the first voltage test point 1 and the first end is S1, and the length of the first end conductive element 2 along the first direction is L1, where S1 / L1 is less than or equal to 0.5. This setting can prevent the extension distance of the first voltage test point 1 along the first direction from being too long, which would lead to excessive transmission resistance of the first voltage test point 1 and affect the accuracy of the test. At the same time, during serial soldering, even if the end of the electrical connector (solder strip) extends above the first voltage test point 1 due to error, it can protect the first fine grid 6 from being soldered off. Therefore, the first voltage test point 1 needs to be slightly close to the first pad 3. Optionally, S1 / L1 is less than or equal to 0.4.

[0058] Exemplarily, S1 / L1 can be 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, or 0.05, etc.

[0059] As shown in the drawings, the back contact cell further comprises a first pad 3 disposed in the first region A, the first pad 3 is electrically connected with the first end of the first end conductive member 2, and the first pad 3 is disposed close to the boundary between the first region A and the second region B. Specifically, the first pad 3 is located between the first end and the edge of the first region A. The current flowing into the first end conductive member 2 from the plurality of first fine grids 6 finally flows to the electrical connector through the first pad 3. In this way, it is more convenient for the electrically conductive connection between the first end conductive member 2 and the electrical connector. Figure 1

[0060] Furthermore, the first pad 3 is connected with at least one first fine grid 6. In this way, the current of the first fine grid 6 connected with the first pad 3 can directly flow to the first pad 3, ensuring that the current of the first fine grid 6 connected with the first pad 3 can flow to the first pad 3 along the shortest distance, shortening the current flow distance, thereby reducing current loss and further improving the reliability and stability of the test. Of course, the first fine grid 6 connected with the first pad 3 can be one, two, three or more.

[0061] In some embodiments, the first voltage test point 1 and the first pad 3 have the same width along the second direction. Or, along the second direction, the first voltage test point 1 and the first pad 3 have the same extension distance. With this technical solution, the first voltage test point 1 and the first pad 3 can be arranged in alignment, ensuring that the length of the first fine grid 6 aligned with the first voltage test point 1 and the first fine grid 6 connected with the first pad 3 is equal, and the current distribution is more uniform, thereby reducing current loss.

[0062] In some embodiments, as shown in the drawings, in the first region A, the cell body comprises a plurality of stacked portions, the plurality of stacked portions are arranged at intervals along the first direction, and the stacked portion comprises the first doped layer 10 and the second doped layer 11 arranged in layers. Specifically, along the first direction, the second doped layer 11 extends to the side of part of the first doped layer 10 away from the semiconductor substrate 13 to form a stacked portion. The first voltage test point 1 is arranged on one stacked portion. Since the height of the stacked portion is high, the first voltage test point 1 is arranged on the stacked portion, which is easier to identify the first voltage test point 1 during the test, thereby improving the test efficiency. Figure 3

[0063] ​​The semiconductor substrate 13 can be made of materials such as silicon (Si), germanium (Ge), or gallium arsenide (GaAs). Obviously, in terms of conductivity type, the semiconductor substrate 13 can be an intrinsically conductive substrate, an n-type conductive substrate, or a p-type conductive substrate. Optionally, the semiconductor substrate 13 can be a p-type conductive substrate or an n-type conductive substrate. Compared to an intrinsically conductive substrate, a p-type conductive substrate or an n-type conductive substrate has better conductivity, resulting in a lower bulk resistivity in the final solar cell, thereby improving the efficiency of the solar cell.

[0064] Furthermore, the materials of the first doped layer 10 and the second doped layer 11 can be silicon (Si), germanium (Ge), silicon carbide (SiCx), or gallium arsenide (GaAs), etc. The first doped layer 10 can be additionally formed on the semiconductor substrate 13 by deposition technology, or it can be formed in the semiconductor substrate 13 by diffusion, ion implantation, or other methods.

[0065] Regarding the conductivity type, the first doped layer 10 can be an n-type doped layer and the second doped layer 11 can be a p-type doped layer; or, the first doped layer 10 can be a p-type doped layer and the second doped layer 11 can be an n-type doped layer.

[0066] Furthermore, the materials of the first doped layer 10 and the second doped layer 11 can be silicon (Si), germanium (Ge), silicon carbide (SiCx), or gallium arsenide (GaAs), etc. Taking the case where both the first doped layer 10 and the second doped layer 11 are made of silicon (Si) as an example, the first doped layer 10 can be one or more of doped polycrystalline silicon, doped amorphous silicon, doped microcrystalline silicon, and doped nanocrystalline silicon. The second doped layer 11 can also be one or more of doped polycrystalline silicon, doped amorphous silicon, doped microcrystalline silicon, and doped nanocrystalline silicon.

[0067] like Figure 3 As shown, in some embodiments, the aforementioned back contact battery may further include a first interface layer 9, which is located at least between the first doped layer 10 and the semiconductor substrate 13. In this case, the passivated contact structure composed of the first interface layer 9 and the first doped layer 10 has excellent interface passivation effect and can achieve selective collection of charge carriers, reducing the carrier recombination rate in the region on the first surface of the semiconductor substrate 13 where the first doped layer 10 is formed, and further improving the photoelectric conversion efficiency of the back contact battery. The material and thickness of the first interface layer 9 can be set according to the material of the first doped layer 10 and actual needs, and are not specifically limited here.

[0068] The material of the first interface layer 9 can be determined based on the material of the first doped layer 10. For example, if the first doped layer 10 includes a doped polycrystalline silicon layer, the first interface layer 9 is a tunneling oxide layer. Thus, the first doped layer 10 and the first interface layer 9 form a tunneling oxide passivation contact. The tunneling oxide passivation technology can form a tunneling film between the first electrode and the semiconductor substrate 13, isolating the electrode from the semiconductor substrate 13, reducing contact recombination losses, and ensuring that electrons can tunnel through the film without affecting current transmission. Simultaneously, passivation can bend the surface bandgap, reducing surface recombination losses on the silicon wafer, effectively improving the problem of front-side passivation and metal contact. Another example: if the first doped layer 10 includes a doped amorphous silicon layer, the first interface layer 9 includes an intrinsic amorphous silicon layer. Furthermore, the embodiments of the present invention do not specifically limit the material of the first interface layer 9.

[0069] In some embodiments, the aforementioned back contact battery may further include a second interface layer 12, which is located at least between the second doped layer 11 and the semiconductor substrate 13. The projection of the second interface layer 12 onto the semiconductor substrate 13 may overlap with the projection of the second doped layer 11 onto the semiconductor substrate 13. In this case, the passivated contact structure formed by the second interface layer 12 and the second doped layer 11 can achieve selective collection of charge carriers and reduce the carrier recombination rate in the region where the second doped layer 11 is formed on the first surface of the semiconductor substrate 13. The material and thickness of the second interface layer 12 can be set according to the material of the second doped layer 11 and actual needs, and are not specifically limited here. For example, when the material of the second doped layer 11 includes one or more of doped amorphous silicon, doped microcrystalline silicon, and doped nanocrystalline silicon, the second interface layer 12 includes one or more of intrinsic amorphous silicon, intrinsic microcrystalline silicon, and intrinsic nanocrystalline silicon. As another example, when the material of the second doped layer 11 includes doped polycrystalline silicon, the second interface layer 12 includes a tunneling oxide layer.

[0070] In other embodiments, such as Figure 1 As shown, the back contact battery also includes a second region B. The first region A and the second region B are arranged sequentially along the first direction. There are two first regions A, one of which is set closer to the first side and the other is set closer to the second side. The second region B is set between the two first regions A.

[0071] The back contact battery also includes a plurality of second pads 8 disposed in the second region B. The plurality of second pads 8 are electrically connected to the first fine grid 6 located in the second region B and are arranged at intervals along the first direction. Specifically, the plurality of second pads 8 are arranged at intervals along the second direction, and each second pad 8 is conductively connected to the first fine grid 6 in the second region B, so as to realize the conductive connection between the first fine grid 6 and the electrical connector through the second pads 8, so that the current in the first fine grid 6 on the second region B can flow to the electrical connector along the shortest distance, thereby reducing current loss.

[0072] Further, along the second direction, the width of the first voltage test point 1, the width of the first pad 3 and the width of the second pad 8 are equal. Specifically, along the second direction, the first voltage test point 1, the first pad 3 and the second pad 8 can be arranged in alignment, ensuring that the length of the first fine grid 6 connected with the first voltage test point 1, the first fine grid 6 connected with the first pad 3 and the first fine grid 6 connected with the second pad 8 are equal, the current distribution is more uniform, thereby reducing current loss.

[0073] Along the first direction, the extension distance of the first voltage test point 1 and the extension distance of the second pad 8 are both less than the extension distance of the first pad 3. It can be understood that the current in the plurality of first fine grids 6 connected with the first end conductive part 2 and the first fine grid 6 directly connected with the first pad 3 are all conducted to the electrical connector through the first pad 3, so the current flowing through the first pad 3 is greater than the current flowing through the second pad 8 and the first voltage test point 1. In this technical solution, by making the extension distance of the first pad 3 along the first direction greater than the extension distance of the second pad 8 and the first voltage test point 1 along the first direction, the conductive volume of the first pad 3 is increased, the transmission resistance of the first pad 3 is reduced, thereby reducing the current loss and improving the power generation efficiency of the back contact battery.

[0074] Optionally, along the first direction, the extension distance of the first pad 3 is greater than or equal to the distance between adjacent first fine grids 6. In this way, the first pad 3 can be directly electrically connected with two or one adjacent first fine grids 6, while avoiding the case that the extension distance of the first pad 3 along the first direction is too large and eventually contacts the second fine grid 5, reducing the risk of electric leakage.

[0075] As Figure 1 and Figure 2As shown, the back contact cell further comprises a second end conductive member 4, which is arranged in the first region A and extends along the first direction. That is, the length direction of the second end conductive member 4 extends along the first direction. The second end conductive member 4 is connected to at least two second fine grids 5. Specifically, each of the plurality of second fine grids 5 adjacent along the first direction is electrically connected to the second end conductive member 4, so that the current of the plurality of second fine grids 5 adjacent along the first direction is converged by the second end conductive member 4. Further, each of the plurality of second fine grids 5 adjacent along the first direction and arranged near the first side is electrically connected to the second end conductive member 4. That is, along the direction from the first side to the second side, the current of the plurality of second fine grids 5 adjacent along the first direction and arranged near the first side is conducted to the electrical connecting member (which can be a solder strip or a main grid) by the second end conductive member 4. In this way, the electrical connecting member is electrically connected to the second end conductive member 4, and the electrical connecting member does not need to extend to the vicinity of the first side, thereby avoiding the situation that the electrical connecting member extending to the vicinity of the first side is easily shaken and dislocated, resulting in electric leakage. In addition, the first fine grid 6 is interrupted at the second end conductive member 4, so as to prevent the second end conductive member 4 from contacting the first fine grid 6 and avoid the risk of electric leakage.

[0076] The second end conductive member 4 and the first end conductive member 2 are arranged alternately along the second direction. At least one second end conductive member 4 is provided with a second voltage test point 7. The second voltage test point 7 and the first voltage test point 1 on the adjacent second end conductive member 4 and the first end conductive member 2 are arranged staggered along the first direction. It can be understood that, in the actual test process, the first voltage test point 1 and the second voltage test point 7 are respectively connected to the positive electrode and the negative electrode of the test equipment, and therefore the first voltage test point 1 and the second voltage test point 7 are generally arranged in pairs.

[0077] Specifically, among the adjacent second end conductive member 4 and the first end conductive member 2, the second voltage test point 7 on the second end conductive member 4 and the first voltage test point 1 on the first end conductive member 2 are arranged staggered along the first direction. By adopting this technical solution, along the first direction, the first voltage test point 1 can be aligned with the first fine grid 6, and the second voltage test point 7 can be aligned with the second fine grid 5, so that the current in the first fine grid 6 aligned with the first voltage test point 1 and the second fine grid 5 aligned with the second voltage test point 7 can flow to the voltage test point through the shortest distance, thereby further reducing the current loss.

[0078] In some embodiments, as shown in FIG. 1, Figure 2 In some embodiments, as shown in FIG. 1,

[0079] Alternatively, in another embodiment, as shown in FIG. 2, Figure 3As shown, the plurality of first end conductive members 2 and the plurality of second end conductive members 4 of the first region A are spaced apart along the second direction, and the plurality of first end conductive members 2 are equally spaced apart along the second direction, and the plurality of second end conductive members 4 are equally spaced apart along the second direction; along the second direction, the distance between adjacent first end conductive members 2 or the distance between adjacent second end conductive members 4 is greater than the distance between adjacent first end conductive members 2 and second end conductive members 4. In this technical solution, the distance between any adjacent first end conductive members 2 is the same, the distance between any adjacent second end conductive members 4 is the same, and the distance between any adjacent first end conductive members 2 is smaller. Such an arrangement can make the current at the edge more evenly collected by the electrical connectors.

[0080] In some embodiments, the first region A is evenly divided into 2 parts along the second direction, and at least one first end conductive member 2 and at least one second end conductive member 4 in each part have voltage test points. With this technical solution, the first voltage test point 1 and the second voltage test point 7 are more evenly distributed in the first region A, avoiding test errors caused by uneven regions, and further improving the accuracy of the back contact battery test.

[0081] As shown, Figure 1 The back surface of the back contact battery includes two first regions A and a second region B located between the two first regions A, i.e. along the first direction, the second region B is located between the two first regions A. Any first region A is evenly divided into 2 parts, and at least one first end conductive member 2 and at least one second end conductive member 4 in each part have voltage test points. Thus, taking the center of the first surface as the origin, coordinate axes are formed along the first direction and the second direction, and at least one pair of first voltage test points 1 and second voltage test points 7 are arranged in each of the four quadrants of the first surface, further ensuring the uniformity of the voltage test point distribution and reducing test errors caused by uneven regions.

[0082] For example, if the total number of first end conductive members 2 and second end conductive members 4 is 18, voltage test points can be arranged on only part of the end conductive members, or of course on all the end conductive members. In the case of arranging voltage test points on part of the end conductive members, voltage test points can be arranged on any two adjacent end conductive members among the 3rd to 6th end conductive members along the first direction, and voltage test points can be arranged on any two adjacent end conductive members among the 13th to 16th end conductive members along the first direction. In this way, at least one pair of first voltage test points 1 and second voltage test points 7 can be arranged in each of the four quadrants of the first surface.

[0083] In some embodiments, as shown, Figure 1 and Figure 2As shown in the figure, among the first end conductive member 2 and the second end conductive member 4 adjacent in the second direction, the first voltage test point 1 on the first end conductive member 2 is electrically connected with a first fine grid 6, and the second voltage test point 7 on the second end conductive member 4 is electrically connected with a second fine grid 5. By adopting the technical scheme, the current in the first fine grid 6 connected with the first voltage test point 1 and the second fine grid 5 connected with the second voltage test point 7 can flow to the first voltage test point 1 or the second voltage test point 7 in the shortest distance, further reducing the current loss and improving the accuracy of the test.

[0084] The above technical scheme, as shown in the figure, Figure 1 As shown in the figure, among the first end conductive member 2 and the second end conductive member 4 adjacent in the second direction, the first fine grid 6 electrically connected with the first voltage test point 1 on the first end conductive member 2 and the second fine grid 5 electrically connected with the second voltage test point 7 on the second end conductive member 4 are arranged adjacent in the first direction. By arranging in this way, the distance between the first voltage test point 1 and the second voltage test point 7 on the adjacent first end conductive member 2 and the second end conductive member 4 is smaller, and the accuracy of the test is higher.

[0085] In the first direction, the difference between the extension distances of the first end conductive member 2 and the second end conductive member 4 is the interval between the adjacent first fine grid 6 and the second fine grid 5. By arranging in this way, the arrangement positions of the first end conductive member 2 and the second end conductive member 4 in the first direction are roughly aligned, the current flowing through the first end conductive member 2 and the second end conductive member 4 is roughly the same, the situation of local current being too large and temperature being too high is avoided, and the stability of the performance of the whole back contact battery is ensured.

[0086] In other embodiments, as shown in the figure, Figure 1 The first fine grid 6 connected with the first voltage test point 1 on the first end conductive member 2 and the first pad 3 are spaced apart by at least one first fine grid 6. For example, the first fine grid 6 connected with the first voltage test point 1 on the first end conductive member 2 and the first pad 3 are spaced apart by 1, 2, 3 or more first fine grids 6. By adopting the technical scheme, the distance between the first voltage test point 1 and the first pad 3 is ensured to be far, the test is avoided from being affected by the current collection of the first pad 3, and the accuracy of the test is further improved.

[0087] In some embodiments, as shown in the figure, Figure 1As shown, the first end conductive member 2 is electrically connected with at least 5 first fine grids 6. That is, at least 5 first fine grids 6 closest to the first edge are electrically connected with the first end conductive member 2. The second end conductive member 4 is electrically connected with at least 5 second fine grids 5. That is, at least 5 second fine grids 5 closest to the first edge are electrically connected with the second end conductive member 4. In the case of electrically connecting the electrical connecting member with the first end conductive member 2 or the second end conductive member 4, the electrical connecting member does not necessarily extend to the vicinity of the first edge, and the distance between the end of the electrical connecting member and the first edge is large, which avoids the electrical connecting member extending to the vicinity of the first edge from easily shaking and mispositioning, thus causing the leakage of electricity.

[0088] For example, the first end conductive member 2 is electrically connected with 5, 6, 7 or more first fine grids 6. The second end conductive member 4 is electrically connected with 5, 6, 7 or more second fine grids 5.

[0089] In other embodiments, the width of the first end conductive member 2 along the second direction gradually decreases in the direction from the second region B to the first region A, that is, along the direction close to the first edge. Similarly, the width of the second end conductive member 4 along the second direction gradually decreases in the direction from the second region B to the first region A. It can be understood that the current flowing through the inside of the first end conductive member 2 or the second end conductive member 4 gradually increases along the direction close to the second region B, and therefore the width of the first end conductive member 2 or the second end conductive member 4 gradually increases along the direction close to the second region B in this technical solution, so as to gradually reduce the transmission resistance of the first end conductive member 2 or the second end conductive member 4, and the transmission resistance of the first end conductive member 2 or the second end conductive member 4 is adapted to the current flowing through the inside, which further reduces the current loss, thereby improving the efficiency of the solar cell.

[0090] In addition, the embodiments of the present application also provide a photovoltaic module, which comprises the back contact cell provided by any of the above embodiments and the electrical connecting member. The electrical connecting member is electrically connected with the plurality of first fine grids 6 or the plurality of second fine grids 5, and the electrical connecting member can be a main grid or a solder strip. Compared with the prior art, the photovoltaic module provided by the embodiments of the present application has the same beneficial effects as the back contact cell described above, and will not be described here.

[0091] In a specific embodiment, the back contact cell further comprises a first pad 3 arranged in the first region A, the first pad 3 is electrically connected with the first end of the first end conductive member 2, and the first pad 3 is arranged close to the boundary between the first region A and the second region B. In the first direction, the end of the electrical connecting member is located between the first pad 3 and the first voltage test point 1. In this way, it can be ensured that the electrical connecting member can be well electrically connected with the first pad 3, and it can also prevent the electrical connecting member from affecting the cooperation connection of the first voltage test point 1 and the test probe.

[0092] In the description of the above-mentioned embodiments, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0093] The above description is merely illustrative of the application, and the scope of the application is not limited thereto. Any variations and modifications of the application, which fall within the scope of the application, are to be considered as within the scope of the application. Therefore, the scope of the application should be determined by the scope of the claims.

Claims

1. A back contact cell, characterized in that, The battery body comprises a first surface and a second surface arranged oppositely, the first surface has a first edge and a second edge arranged oppositely along a first direction and a third edge and a fourth edge arranged oppositely along a second direction; the first surface further comprises a first region close to the first edge; a plurality of first fine grids and a plurality of second fine grids are arranged on the first surface and are alternately distributed along the first direction and extend along the second direction, the first direction intersects the second direction, the first fine grids and the second fine grids are different in polarity; a first end conductive member is arranged on the first region and extends along the first direction, and connects at least two first fine grids, and the second fine grids are interrupted at the first end conductive member; at least one of the first end conductive members has a first voltage test point; the first end conductive member comprises a first end portion away from the first edge; the distance between the first voltage test point and the first end portion is S1, and the length of the first end conductive member along the first direction is L1, S1 / L1 is less than or equal to 0.5; the back contact battery further comprises a first pad arranged on the first region, the first pad is electrically connected with the first end portion of the first end conductive member, and the first pad is connected with at least one first fine grid. The width of the first voltage test point along the second direction is greater than the width of the first end conductive member along the second direction.

2. The back contact cell of claim 1, wherein, The first voltage test point is arranged at the intersection position of the first fine grid and the first end conductive member.

3. The back contact cell of claim 1, wherein, The width of the first voltage test point along the second direction is equal to the width of the first pad along the second direction.

4. The back contact cell of claim 1, wherein, In the first region, the battery body comprises a plurality of stacked portions, a plurality of the stacked portions are arranged at intervals along the first direction, and the stacked portion comprises a first doped layer and a second doped layer arranged in layers, and the first voltage test point is arranged on one of the stacked portions.

5. The back contact cell of claim 1, wherein, Further comprising a second region away from the first region and adjacent to the first region, a plurality of second pads are arranged on the second region, a plurality of the second pads are electrically connected with the first fine grids located in the second region and are arranged at intervals along the first direction; 6. The back contact cell of claim 1, wherein along the second direction, the width of the first voltage test point, the width of the first pad and the width of the second pad are equal; and / or, along the first direction, the extension distance of the first voltage test point and the extension distance of the second pad are both less than the extension distance of the first pad. Further comprising a second end conductive member arranged on the first region and extending along the first direction, the second end conductive member and the first end conductive member are arranged alternately at intervals along the second direction, at least one of the second end conductive members is provided with a second voltage test point, and the second voltage test point and the first voltage test point on the adjacent second end conductive member and the first end conductive member are arranged staggered along the first direction.

7. The back contact cell of claim 1, wherein, along the second direction, the first region is equally divided into two parts, and at least one of the first end conductive members and at least one of the second end conductive members in each part have voltage test points; and / or, 8. The back contact cell of claim 7, wherein, ​ The back surface of the back contact cell comprises two first regions and a second region between the two first regions, any of the first regions is divided into two parts averagely, and at least one first end conductive piece and at least one second end conductive piece in each part are provided with voltage test points.

9. The back contact cell of claim 7, wherein, Among the first end conductive pieces and the second end conductive pieces adjacent along the second direction, the first voltage test point on the first end conductive piece is electrically connected with a first fine grid, and the second voltage test point on the second end conductive piece is electrically connected with a second fine grid, and the first fine grid electrically connected with the first voltage test point and the second fine grid electrically connected with the second voltage test point are arranged adjacent along the first direction.

10. The back contact cell of claim 1, wherein, The first end conductive piece is electrically connected with at least 5 first fine grids.

11. The back contact cell of claim 1, wherein, Along the direction close to the first edge, the width of the first end conductive piece along the second direction gradually decreases.

12. A photovoltaic module, characterized by The back contact cell comprises the back contact cell and an electrical connector according to any one of claims 1-11, and the electrical connector is electrically connected with a plurality of first fine grids.

13. The photovoltaic module of claim 12, wherein, The first end conductive piece comprises a first end away from the first edge; the back contact cell further comprises a first pad arranged on the first region, and the first pad is electrically connected with the first end of the first end conductive piece. Along the first direction, the end of the electrical connector is located between the first pad and the first voltage test point.

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