A photovoltaic bifacial cell and module

Abstract

The application relates to the technical field of semiconductors, and discloses a photovoltaic double-sided cell and assembly, which comprises a first unit piece and a second unit piece, the first unit piece is superposed with the second unit piece, in a first direction, the first unit piece is provided with a first surface and a second surface, the second unit piece is provided with a third surface and a fourth surface, the second surface is opposite to the third surface and is connected through metallization of a metal layer. The application can increase the light-receiving area of a solar cell, improve the double-sided rate, and improve the utilization rate of photovoltaic installation space.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more particularly to a photovoltaic bifacial cell and module. Background Technology

[0002] Most existing solar cells have grid lines on both sides of the cell (such as Topcon cells and PERC cells), while others have grid lines on only one surface of the cell (such as back contact cells, i.e., BC cells).

[0003] However, the area of ​​these two types of solar cells that can receive light is limited by the grid lines, resulting in limited power and a relatively low bifaciality. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a photovoltaic bifacial cell that increases the light-receiving area of ​​the solar cell, improves the bifaciality, and increases the utilization rate of photovoltaic installation space.

[0005] To solve the above-mentioned technical problems, the present invention provides a photovoltaic bifacial cell, including a first unit cell and a second unit cell, wherein the first unit cell and the second unit cell are stacked together. In a first direction, the first unit cell has a first surface and a second surface, and the second unit cell has a third surface and a fourth surface. The second surface and the third surface are opposite to each other and are connected by metallization through a metal layer.

[0006] As an improvement to the above solution, both the first surface and the fourth surface are textured.

[0007] As an improvement to the above solution, the first unit chip is provided with a first metal grid line protruding towards the second surface, and the metal layer is formed by sintering the first metal grid line at high temperature.

[0008] As an improvement to the above solution, the second unit chip has a second grid groove corresponding to the first metal grid line on the third surface, and in the first direction, the projection of the first metal grid line and the projection of the second grid groove at least partially coincide; and / or

[0009] The first unit chip has a first grid groove on the second surface, and in a first direction, the projection of the first metal grid line at least partially overlaps with the projection of the first grid groove.

[0010] As an improvement to the above solution, the first metal grid line completely covers the first grid line slot, and when the first unit piece and the second unit piece are stacked, the first metal grid line completely covers the second grid line slot.

[0011] As an improvement to the above solution, the shape of the second grid groove is similar to the shape of the first metal grid line, and the shape of the first grid groove is similar to the shape of the first metal grid line.

[0012] As an improvement to the above solution, the first grid groove and the second grid groove are arranged in a mirror symmetrical manner, and in the first direction, the height of the first grid groove is less than 1 / 2 of the height of the first metal grid line.

[0013] As an improvement to the above scheme, the width of the first grid groove and the second grid groove are both 5~30um, and the depth of the first grid groove and the second grid groove in the first direction is both 0.5~2um.

[0014] As an improvement to the above scheme, the first metal gate line includes a first P-region gate line and a first N-region gate line;

[0015] In the first direction, the height of the first unit cell and the second unit cell is 100~150um, the height of the first P-region gate line is 10~20um, and the height of the first N-region gate line is 11~23um.

[0016] As an improvement to the above solution, the first unit sheet is provided with a first metal grid line protruding towards the second surface, and the second unit sheet is provided with a second metal grid line protruding towards the third surface. The metal layer is formed by high-temperature sintering of the first metal grid line and the second metal grid line.

[0017] As an improvement to the above scheme, the first metal gate line includes a first P-region gate line and a first N-region gate line, and the second metal gate line includes a second P-region gate line and a second N-region gate line.

[0018] In the first direction, the height of the first unit cell and the second unit cell are both 100um~150um, the height of the first P-region gate line and the second P-region gate line are both 5~10um, the height of the first N-region gate line and the second N-region gate line are both 6~11um, and the sum of the heights of the first P-region gate line and the second P-region gate line is 10~20um, and the sum of the heights of the first N-region gate line and the second N-region gate line is 12~23um.

[0019] As an improvement to the above scheme, the side of the first P-region gate line that is away from the second surface and the side of the first N-region gate line that is away from the second surface are on the same plane.

[0020] The side of the second P-region gate line that is away from the third surface and the side of the second N-region gate line that is away from the third surface are on the same plane.

[0021] As an improvement to the above solution, the first unit chip has a first grid groove on the second surface that is opposite to the first metal grid line. In the first direction, the projection of the first metal grid line and the projection of the first grid groove at least partially overlap.

[0022] The second unit chip has a second grid groove on the third surface that is opposite to the second metal grid line, and in the first direction, the projection of the second metal grid line and the projection of the second grid groove at least partially overlap.

[0023] As an improvement to the above solution, the first metal grid line completely covers the first grid line slot, and the second metal grid line completely covers the second grid line slot.

[0024] The projections of the first metal grid line and the second metal grid line in the first direction completely coincide, and the shapes of the first metal grid line and the second metal grid line are similar to the shape of the second grid line groove.

[0025] As an improvement to the above solution, the second surface and the third surface are provided with matching limiting protrusions and limiting grooves, and the limiting protrusions are provided on the outer edge of the second surface or the third surface.

[0026] As an improvement to the above solution, the first metal grid line includes a main grid line extending along a second direction, and a first sub-grid line and a second sub-grid line extending along a third direction. The first sub-grid line and the second sub-grid line are respectively disposed on both sides of the main grid line and connected to the main grid line. The first direction, the second direction, and the third direction are arranged to intersect each other.

[0027] As an improvement to the above scheme, the width of the main gate line in the third direction is 200~500um, and the width of the first sub-gate line and the second sub-gate line in the second direction is 18~28um.

[0028] As an improvement to the above scheme, in the second direction, the first sub-gate line of the main gate line is adjacent to and alternately arranged with the second sub-gate line on the adjacent main gate line, and the second sub-gate line of the main gate line is adjacent to and alternately arranged with the first sub-gate line on the adjacent main gate line.

[0029] As an improvement to the above scheme, the projection portion of the second sub-grid line adjacent to the first sub-grid line in the second direction coincides with the projection portion of the first sub-grid line in the second direction.

[0030] As an improvement to the above scheme, the projections of the first and second sub-grid lines of the same main grid line in a third direction are staggered.

[0031] As an improvement to the above solution, in the third aspect, the main grid line, the first sub-grid line, and the second sub-grid line are all provided with a preset distance from the groove wall of the first grid line groove.

[0032] As an improvement to the above solution, in the second direction, the main grid line is in contact with the groove wall of the first grid line groove, and the first auxiliary grid line and the second auxiliary grid line are both provided with a preset distance from the groove wall of the first grid line groove.

[0033] In addition, the present invention also provides a photovoltaic bifacial cell module, which includes the above-mentioned photovoltaic bifacial cell, wherein the first unit cell is provided with a first conductive path, the second unit cell is provided with a second conductive path, and both the first conductive path and the second conductive path are connected to the metal layer.

[0034] The first conductive path of the photovoltaic bifacial cell is connected to the second conductive path of the adjacent photovoltaic bifacial cell.

[0035] As an improvement to the above scheme, the first conductive path and the second conductive path are respectively located at the two ends of the photovoltaic bifacial cell in the second direction, and the photovoltaic bifacial cell is mounted on the adjacent photovoltaic bifacial cell so that the first conductive path of the photovoltaic bifacial cell is connected to the second conductive path of the adjacent photovoltaic bifacial cell.

[0036] As an improvement to the above solution, the first surface is provided with a first conductive groove, the first conductive groove is provided with a preset distance from the second surface, the first conductive path is a first conductive element provided in the first conductive groove, the first conductive element is connected to the first metal grid line, and the fourth surface is provided with a second conductive groove, the second conductive groove is connected to the second grid line groove.

[0037] In addition, the present invention also provides another photovoltaic bifacial cell module, which includes the above-mentioned photovoltaic bifacial cell, wherein the first unit cell is provided with a first conductive path, the second unit cell is provided with a second conductive path, the first conductive path is connected to the first metal grid line, and the second conductive path is connected to the second metal grid line.

[0038] As an improvement to the above solution, the first surface is provided with a first conductive groove, the first conductive groove is provided with a preset distance from the second surface, the first conductive path is a conductive element provided in the first conductive groove, the conductive element is connected to the first metal grid line, the fourth surface is provided with a second conductive groove, the second conductive groove is provided with a preset distance from the third surface, the second conductive path is a second conductive element provided in the second conductive groove, the second conductive element is connected to the second metal grid line.

[0039] Implementing this invention has the following beneficial effects:

[0040] This invention discloses a bifacial photovoltaic cell, which is composed of a first unit cell and a second unit cell stacked together. Specifically, the second surface of the first unit cell is aligned with the third surface of the second unit cell, and the second and third surfaces of the first and second unit cells are connected by a metal layer to form a complete bifacial photovoltaic cell. The metal layer of the bifacial photovoltaic cell is equivalent to a metal electrode and is hidden between the first and second unit cells, that is, inside the bifacial photovoltaic cell. The first surface of the first unit cell and the fourth surface of the second unit cell serve as the outer surface of the entire bifacial photovoltaic cell and also as the light-receiving surface. Neither of them has metal electrodes (grid lines). The overall light-receiving area of ​​the bifacial photovoltaic cell is increased, improving the utilization rate of photovoltaic installation space. Moreover, the power generation of the first and fourth surfaces is close, and the bifaciality is improved compared with back contact cells. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the structure of an embodiment of a photovoltaic bifacial cell according to the present invention;

[0042] Figure 2 yes Figure 1 A schematic diagram of the structure of a first embodiment of a photovoltaic bifacial cell before the metallized interconnected metal layers are formed by high-temperature sintering;

[0043] Figure 3 yes Figure 2 A schematic diagram of the structure of the second unit piece;

[0044] Figure 4 yes Figure 3 Side view;

[0045] Figure 5 yes Figure 2 A schematic diagram of the structure of the first unit piece;

[0046] Figure 6 yes Figure 5 A magnified structural diagram of part A;

[0047] Figure 7 yes Figure 5 A schematic diagram of the structure of the first unit piece as observed from the second direction;

[0048] Figure 8 yes Figure 1 A schematic diagram of the second embodiment of a photovoltaic bifacial cell before the metallized interconnected metal layers are formed by high-temperature sintering;

[0049] Figure 9 This is a schematic diagram of an embodiment of a photovoltaic bifacial cell module;

[0050] Figure 10 yes Figure 9 A bottom view;

[0051] Figure 11 yes Figure 9 Side view;

[0052] Figure 12 yes Figure 9 A schematic diagram of the structure of the first unit piece in the diagram;

[0053] Figure 13 yes Figure 12 BB cross-sectional view;

[0054] Figure 14 yes Figure 9 A schematic diagram of the structure of the second unit piece;

[0055] Figure 15 yes Figure 9 A schematic diagram of the connection structure between two adjacent bifacial photovoltaic cells. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0057] like Figures 1 to 7 As shown, the present invention discloses a first embodiment of a photovoltaic bifacial cell, including a first unit sheet 1 and a second unit sheet 2. The first unit sheet 1 and the second unit sheet 2 are stacked together. In a first direction, the first unit sheet 1 is provided with a first surface 11 and a second surface 12. The second unit sheet 2 is provided with a third surface 21 and a fourth surface 22. The second surface 12 is opposite to the third surface 21 and is connected by metallization through a metal layer.

[0058] The photovoltaic bifacial cell in this embodiment is formed by stacking a first unit cell 1 and a second unit cell 2. Specifically, the second surface 12 of the first unit cell 1 and the third surface 21 of the second unit cell 2 are aligned, and the second surface 12 of the first unit cell 1 and the third surface 21 of the second unit cell 2 are connected by a metal layer to form a complete photovoltaic bifacial cell. The metal layer of the photovoltaic bifacial cell is equivalent to a metal electrode and is hidden between the first unit cell 1 and the second unit cell 2, that is, inside the photovoltaic bifacial cell. The first surface 11 of the first unit cell 1 and the fourth surface 22 of the second unit cell 2 serve as the outer surface of the entire photovoltaic bifacial cell and also as the light-receiving surface. There are no metal electrodes (grid lines) in either of them. The overall light-receiving area of ​​the photovoltaic bifacial cell is increased, which improves the utilization rate of photovoltaic installation space. Moreover, the power generation of the first surface 11 and the fourth surface 22 are close, and the bifaciality is improved compared with the back contact cell.

[0059] Preferably, both the first surface 11 and the fourth surface 22 are textured. By using chemical etching, a microscopic pyramidal uneven structure, i.e., a textured surface, can be formed on the outer surface of the photovoltaic bifacial cell to significantly reduce the reflectivity of sunlight, thereby capturing more photons to generate electricity and improving luminous efficiency. By forming textured surfaces on both the first surface 11 and the fourth surface 22, the power generation capabilities of the first surface 11 and the fourth surface 22 of the bifacial cell are made as similar as possible, achieving a bifaciality of nearly 100%.

[0060] In the first embodiment, the structure of the first unit sheet 1 is similar to that of the back contact battery, that is, the first unit sheet 1 has grid lines on one of its surfaces, and the surface with the grid lines faces the light-receiving surface. In this embodiment, the thickness of the first unit sheet 1 can be reduced based on the existing back contact battery structure so that the overall thickness of the photovoltaic bifacial battery formed by stacking the first unit sheet 1 and the second unit sheet 2 is not too large. Preferably, the height of the first unit sheet 1 in the first direction is set to 100~150µm, and the height of the second unit sheet 2 in the first direction is also set to 100~150µm. Preferably, slots can be made at the electrode positions of both the first unit sheet 1 and the second unit sheet 2 to facilitate the formation of a metallized interconnected metal layer along a predetermined path and to reduce the overall thickness of the battery cell.

[0061] Specifically, the first unit chip 1 is provided with a first metal gate line 13 protruding towards the second surface 12. The first metal gate line 13 includes a first P-region gate line and a first N-region gate line. In a first direction, the height of the first P-region gate line is 10~20um, and the height of the first N-region gate line is 11~23um. The metal layer is formed by high-temperature sintering of the first metal gate line 13. After high-temperature sintering, the first metal gate line 13 forms an electrode that is electrically connected to both the semiconductor region of the first unit chip 1 and the semiconductor region of the second unit chip 2.

[0062] The second cell 2 has a second grid groove 211 on its third surface 21, corresponding to the first metal grid line 13. In the first direction, the projection of the first metal grid line 13 and the projection of the second grid groove 211 at least partially overlap. When the first metal grid line 13 is sintered at high temperature, a portion of the metal layer will enter the second grid groove 211, forming a tight connection between the metal layer and the second cell 2, and reducing the overall thickness of the cell.

[0063] More preferably, the first cell 1 has a first grid groove 121 on the second surface 12, and in the first direction, the projection of the first metal grid line 13 at least partially overlaps with the projection of the first grid groove 121. When the first metal grid line 13 is sintered at high temperature, a portion of the metal layer will enter the first grid groove 121 and the second grid groove 211, and the metal layer will form a tight connection with the first cell 1 and the second cell 2, which can further reduce the overall thickness of the cell.

[0064] Furthermore, the first metal grid line 13 completely covers the first grid line slot 121, and when the first unit cell 1 and the second unit cell 2 are stacked, the first metal grid line 13 completely covers the second grid line slot 211. That is, compared with the first metal grid line 13, the first grid line slot 121 and the second grid line slot 211 are smaller in width. On the one hand, this can minimize the damage to the battery cell caused by slotting and reduce power loss. On the other hand, it is more convenient to manufacture the grid line and avoids the problem of excessive resistance caused by the grid line being too thin, which reduces the battery power.

[0065] Preferably, in the first direction, the groove depth of the first grid groove 121 is less than 1 / 2 of the height of the first metal grid line 13, which reduces damage to the battery cell. At the same time, it makes the projected area of ​​the metal layer formed by the first metal grid line 13 on the second and third surfaces larger. In addition to filling the first grid groove 121 and the second grid groove 211, the metal layer formed by the first metal grid line 13 can also be tightly connected with the second surface 12 and the third surface 21, further enhancing the overall stability of the battery cell.

[0066] Preferably, the shape of the second grid groove 211 is similar to the shape of the first metal grid line 13, and the shape of the first grid groove 121 is similar to the shape of the first metal grid line 13, so that the metal layer is evenly distributed around the first grid groove 121 and the second grid groove 211, and the first unit sheet 1 and the second unit sheet 2 are more firmly connected through the metal layer. The first metal grid line 13 is uniformly metallized and connected to the first unit sheet 1 and the second unit sheet 2, forming a bifacial cell with a thickness comparable to that of existing photovoltaic cells.

[0067] In this embodiment, the first grid groove 121 on the first unit plate 1 and the second grid groove 211 on the second unit plate 2 are preferably arranged in a mirror symmetrical manner, so that the area of ​​the metal layer formed by the high-temperature sintering of the first metal grid line 13 and the first unit plate 1 and the second unit plate 2 are consistent, and the structure of the entire photovoltaic bifacial cell is stable.

[0068] When the first unit sheet 1 and the second unit sheet 2 are pressed together, and the first metal grid line 13 is sintered at high temperature, the first metal grid line 13 will form a metal layer along the first grid line groove 121 and the second grid line groove 211, and the first metal grid line 13 will metallize and connect the first unit sheet 1 and the second unit sheet 2 according to a predetermined path.

[0069] To facilitate the positioning between the first unit piece 1 and the second unit piece 2, this embodiment provides matching limiting protrusions and limiting grooves on the second surface 12 and the third surface 21. The limiting protrusions are located on the outer edge of the second surface 12 or the third surface 21.

[0070] In this embodiment, the first metal gate line includes a first P-region gate line and a first N-region gate line. In the first direction, the height of the first P-region gate line is 10~20um, and the height of the first N-region gate line is 11~23um.

[0071] The first P-region gate line and the first N-region gate line of the first metal gate line 13 each specifically include a main gate line 131 extending along a second direction, and a first sub-gate line 132 and a second sub-gate line 133 extending along a third direction. The first sub-gate line 132 and the second sub-gate line 133 are respectively disposed on both sides of the main gate line 131 and connected to the main gate line 131. The width of the main gate line in the third direction is 200~500um, and the width of the first sub-gate line and the second sub-gate line in the second direction is 18~28um. The first direction, the second direction, and the third direction are arranged intersecting each other. The main gate line 131 is responsible for converging the current collected by the first sub-gate line 132 and the second sub-gate line 133.

[0072] Preferably, in the second direction, the first sub-gate line 132 of the main gate line 131 is adjacent to and alternately arranged with the second sub-gate line 133 on the adjacent main gate line 131, and the second sub-gate line 133 of the main gate line 131 is adjacent to and alternately arranged with the first sub-gate line 132 on the adjacent main gate line 131; in addition, the projection portions of the adjacent second sub-gate lines 133 and the first sub-gate lines 132 in the second direction coincide, so as to increase the arrangement density of the first metal gate line 13 per unit area.

[0073] The first sub-grid line 132 and the second sub-grid line 133 of the same main grid line 131 are staggered in the projection of the third direction. On the basis of increasing the arrangement density of the first metal grid line 13 per unit area, the first metal grid line 13 can be arranged along the third direction, the first grid line groove 121 can also be arranged along the third direction, and similarly, the second grid line groove 211 can also be arranged along the third direction, which facilitates processing.

[0074] The width of both the first and second gate slots is 5-30 μm, and the depth of both in the first direction is 0.5-2 μm. Since the shapes of the first gate slot 121 and the second gate slot 211 are similar to the shape of the first metal gate wire 13, each of the first and second gate slots includes a main slot corresponding to the main gate wire 131, a first secondary slot corresponding to the first secondary gate wire 132, and a second secondary slot corresponding to the second secondary gate wire 133. The width of the first and second gate slots refers to the fact that the numerical range of the width of the main slot, the first secondary slot, and the second secondary slot all fall within 5-30 μm.

[0075] Combination Figures 9 to 15 Based on the first embodiment of a bifacial photovoltaic cell, the present invention also provides a bifacial photovoltaic cell module, which includes the bifacial photovoltaic cell of the first embodiment. The first unit cell 1 is provided with a first conductive path 14, and the second unit cell 2 is provided with a second conductive path 24. Both the first conductive path 14 and the second conductive path 24 are connected to the metal layer. The first conductive path 14 of the bifacial photovoltaic cell is connected to the second conductive path 24 of an adjacent bifacial photovoltaic cell. The first conductive path 14 of the bifacial photovoltaic cell can be electrically connected to the second conductive path 24 of an adjacent bifacial photovoltaic cell through conductive connectors such as wires.

[0076] Preferably, in this embodiment, the first conductive path 14 and the second conductive path 24 are respectively disposed at the two ends of the photovoltaic bifacial cell in the second direction. The photovoltaic bifacial cell is mounted on an adjacent photovoltaic bifacial cell, so that the first conductive path 14 of the photovoltaic bifacial cell is in contact with the second conductive path 24 of the adjacent photovoltaic bifacial cell for electrical conduction. When the photovoltaic bifacial cell module has multiple photovoltaic bifacial cells, the multiple photovoltaic bifacial cells are arranged in a shingled manner to realize the electrical connection between two adjacent photovoltaic bifacial cells.

[0077] Specifically, in this embodiment, a first conductive groove a is formed on the first surface 11 of the first unit plate 1, the first conductive groove a is provided at a preset distance from the second surface 12, the first conductive passage 14 is a first conductive element disposed in the first conductive groove a, the first conductive element is connected to the first metal grid line 13, and a second conductive groove b is formed on the fourth surface 22 of the second unit plate 2, the second conductive groove b is connected to the second grid line groove 211.

[0078] In addition, such as Figure 8As shown, this invention discloses a second embodiment of a photovoltaic bifacial cell. In this second embodiment, the structure of the first unit sheet 1 and the second unit sheet 2 is similar to that of a back-contact cell; that is, both the first unit sheet 1 and the second unit sheet 2 have grid lines on one of their surfaces, and the surface with the grid lines faces the light-receiving surface. In this embodiment, the thickness of the first unit sheet 1 and the second unit sheet 2 can be reduced based on the existing back-contact cell structure so that the overall thickness of the stacked photovoltaic bifacial cell is not excessive. In the first direction, the height of both the first unit sheet 1 and the second unit sheet 2 is preferably 100µm to 150µm.

[0079] The first unit plate 1 is provided with a first metal grid line 13 protruding towards the second surface 12, and the second unit plate 2 is provided with a second metal grid line 23 protruding towards the third surface 21. The metal layer is formed by high-temperature sintering of the first metal grid line 13 and the second metal grid line 23, that is, the first metal grid line 13 and the second metal grid line 23, the first metal grid line 13 and the first unit plate 1, and the second metal grid line 23 and the second unit plate 2 are mutually metallized.

[0080] The first metal gate line includes a first P-region gate line and a first N-region gate line, and the second metal gate line includes a second P-region gate line and a second N-region gate line. In the first direction, the height of the first P-region gate line and the second P-region gate line is 5~10um, the height of the first N-region gate line and the second N-region gate line is 6~11um, and the sum of the heights of the first P-region gate line and the second P-region gate line is 10~20um, and the sum of the heights of the first N-region gate line and the second N-region gate line is 12~23um.

[0081] For cells where the height of the P-region and the N-region are the same, the heights of the first P-region grid lines and the first N-region grid lines are set to be the same, and the heights of the second P-region grid lines and the second N-region grid lines are also set to be the same. For cells where the heights of the P-region and the N-region are not the same, the heights of the first P-region grid lines and the first N-region grid lines may be inconsistent, as may the heights of the second P-region grid lines and the second N-region grid lines. Preferably, the side of the first P-region grid line facing away from the second surface and the side of the first N-region grid line facing away from the second surface are on the same plane; the side of the second P-region grid line facing away from the third surface and the side of the second N-region grid line facing away from the third surface are also on the same plane. This ensures that when the first unit sheet 1 and the second unit sheet 2 are stacked, the surfaces where the first P-region grid lines and the second P-region grid lines, and the first N-region grid lines and the second N-region grid lines are in contact are all on the same plane. This results in good balance when the first unit sheet 1 and the second unit sheet 2 are stacked, which is beneficial for forming a uniform metal layer.

[0082] Preferably, the first unit cell has a first grid groove 121 on its second surface opposite to the first metal grid line 13, and in a first direction, the projection of the first metal grid line 13 at least partially overlaps with the projection of the first grid groove 121. Furthermore, the second unit cell has a second grid groove 211 on its third surface opposite to the second metal grid line 23, and in a first direction, the projection of the second metal grid line 23 at least partially overlaps with the projection of the second grid groove 211. When the first metal grid line 13 and the second metal grid line 23 are sintered at high temperature, a portion of the metal layer will enter the first grid groove 121 and the second grid groove 211, forming a tight connection between the metal layer and the first unit cell 1 and the second unit cell 2, and further reducing the overall thickness of the battery cell. That is, when the first metal grid line 13 and the second metal grid line 23 are sintered at high temperature to form a metal layer, and the second surface 12 and the third surface 21 are connected by metallization through the metal layer, the metal layer diffuses into the first grid line groove 121 and the second grid line groove 211, so that the second surface 12 and the third surface 21 can be closely attached to form the entire photovoltaic bifacial cell.

[0083] The first metal grid line 13 completely covers the first grid line slot 121, and the second metal grid line 23 completely covers the second grid line slot 211. That is, the first grid line slot 121 is narrower than the first metal grid line 13, and the second grid line slot 211 is narrower than the second metal grid line 23. On the one hand, this can minimize the damage to the battery cell caused by slotting and reduce power loss. On the other hand, it is easier to manufacture the grid lines and avoids the problem of excessive resistance caused by overly thin grid lines, which reduces battery power.

[0084] In this embodiment, the first grid groove 121 on the first unit plate 1 and the second grid groove 211 on the second unit plate 2 are preferably arranged in a mirror symmetrical manner, so that the area of ​​the metal layer formed by the high-temperature sintering of the first metal grid line 13 and the first unit plate 1 are combined with the area of ​​the metal layer formed by the high-temperature sintering of the second metal grid line 23 and the second unit plate 2 are more consistent, and the structural stability of the entire photovoltaic bifacial cell is better.

[0085] The projections of the first metal grid line 13 and the second metal grid line 23 in the first direction completely overlap, and the shapes of the first metal grid line 13 and the second metal grid line 23 are similar to the shape of the second grid line groove 211. The metal layer formed by the first metal grid line 13 and the second metal grid line 23 can be uniformly distributed around the first grid line groove 121 and the second grid line groove 211, making the connection between the first unit sheet 1 and the second unit sheet 2 more stable. The first metal grid line 13 and the first unit sheet 1 and the second unit sheet 2 are uniformly metallized and connected, forming a bifacial cell with a thickness comparable to that of existing photovoltaic cells.

[0086] To facilitate the positioning between the first unit piece 1 and the second unit piece 2, this embodiment provides matching limiting protrusions and limiting grooves on the second surface 12 and the third surface 21. The limiting protrusions are located on the outer edge of the second surface 12 or the third surface 21.

[0087] In this embodiment, both the first metal gate line 13 and the second metal gate line 23 include a main gate line 131 extending along a second direction, and a first sub-gate line 132 and a second sub-gate line 133 extending along a third direction. The first sub-gate line 132 and the second sub-gate line 133 are respectively disposed on both sides of the main gate line 131 and connected to the main gate line 131. The width of the main gate line in the third direction is 200~500um, and the width of the first sub-gate line and the second sub-gate line in the second direction is 18~28um. The first direction, the second direction, and the third direction are arranged intersecting each other. The main gate line 131 is responsible for converging the current collected by the first sub-gate line 132 and the second sub-gate line 133.

[0088] Preferably, in the second direction, the first sub-gate line 132 of the main gate line 131 is adjacent to and alternately arranged with the second sub-gate line 133 on the adjacent main gate line 131, and the second sub-gate line 133 of the main gate line 131 is adjacent to and alternately arranged with the first sub-gate line 132 on the adjacent main gate line 131; in addition, the projection portions of the adjacent second sub-gate lines 133 and the first sub-gate lines 132 in the second direction coincide, so as to increase the arrangement density of the first metal gate line 13 per unit area.

[0089] The first sub-grid line 132 and the second sub-grid line 133 of the same main grid line 131 are staggered in the projection of the third direction. On the basis of increasing the arrangement density of the first metal grid line 13 per unit area, the first metal grid line 13 can be arranged along the third direction, the first grid line groove 121 can also be arranged along the third direction, and similarly, the second grid line groove 211 can also be arranged along the third direction, which facilitates processing.

[0090] Based on the second embodiment of the photovoltaic bifacial cell, the present invention also provides another photovoltaic bifacial cell module, which includes the aforementioned photovoltaic bifacial cell. The first unit cell 1 is provided with a first conductive path 14, and the second unit cell 2 is provided with a second conductive path 24. The first conductive path 14 is connected to the first metal grid line 13, and the second conductive path 24 is connected to the second metal grid line 23. The first conductive path 14 of the photovoltaic bifacial cell can be electrically connected to the second conductive path 24 of an adjacent photovoltaic bifacial cell through conductive connectors such as wires.

[0091] Specifically, the first surface 11 has a first conductive groove a, which is at a predetermined distance from the second surface 12. The first conductive path 14 is a conductive element disposed within the first conductive groove a, and the conductive element is connected to the first metal grid line 13. The fourth surface 22 has a second conductive groove b, which is at a predetermined distance from the third surface 21. The second conductive path 24 is a second conductive element disposed within the second conductive groove b, and the second conductive element is connected to the second metal grid line 23. When a photovoltaic bifacial solar cell module has multiple photovoltaic bifacial cells, the multiple photovoltaic bifacial cells are arranged in a shingled manner to achieve electrical connection between adjacent photovoltaic bifacial cells. The first conductive groove a is at a preset distance from the second surface 12, and the second conductive groove b is at a preset distance from the third surface 21. That is, both the first conductive groove a and the second conductive groove b are slotted to the depth of the grid line without being penetrated. The first conductive groove a and the second conductive groove b are filled with conductive media such as silver paste, copper paste, and highly conductive adhesive (i.e., the first conductive element and the second conductive element) to form the first conductive path 14 and the second conductive path 24. When two adjacent photovoltaic bifacial cells are connected, the photovoltaic bifacial cell module has an exposed conductive groove except for the photovoltaic bifacial cell located at the outermost edge. The other exposed light-receiving surfaces are all textured, resulting in high luminous efficiency, achieving 100% bifaciality, and improving the utilization rate of photovoltaic installation space.

[0092] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A photovoltaic bifacial cell, characterized in that, It includes a first unit sheet and a second unit sheet, the first unit sheet and the second unit sheet are stacked together. In a first direction, the first unit sheet is provided with a first surface and a second surface, the second unit sheet is provided with a third surface and a fourth surface, the second surface and the third surface are opposite to each other and are connected by metallization through a metal layer. The first unit sheet is provided with a first metal grid line protruding towards the second surface, and the first surface of the first unit sheet and the fourth surface of the second unit sheet, which serve as the light-receiving surfaces of the entire photovoltaic bifacial cell, do not have metal grid lines. The metal layer is formed by sintering the first metal grid line at high temperature.

2. The photovoltaic bifacial cell as described in claim 1, characterized in that, Both the first surface and the fourth surface are textured.

3. The photovoltaic bifacial cell as described in claim 1, characterized in that, The second unit chip has a second grid groove corresponding to the first metal grid line on the third surface, and in a first direction, the projection of the first metal grid line and the projection of the second grid groove at least partially coincide; and / or The first unit chip has a first grid groove on the second surface, and in a first direction, the projection of the first metal grid line at least partially overlaps with the projection of the first grid groove.

4. The photovoltaic bifacial cell as described in claim 3, characterized in that, The first metal grid line completely covers the first grid line slot, and when the first unit piece and the second unit piece are stacked, the first metal grid line completely covers the second grid line slot.

5. The photovoltaic bifacial cell as described in claim 4, characterized in that, The shape of the second grid groove is similar to the shape of the first metal grid line, and the shape of the first grid groove is similar to the shape of the first metal grid line.

6. The photovoltaic bifacial cell as described in claim 3, characterized in that, The first grid groove and the second grid groove are arranged in a mirror symmetrical manner. In the first direction, the groove depth of the first grid groove is less than 1 / 2 of the height of the first metal grid line.

7. The photovoltaic bifacial cell as described in claim 3, characterized in that, The width of the first grid groove and the second grid groove are both 5~30um, and the depth of the first grid groove and the second grid groove is both 0.5~2um in the first direction.

8. The photovoltaic bifacial cell as described in claim 1 or 7, characterized in that, The first metal gate line includes a first P-region gate line and a first N-region gate line; In the first direction, the height of the first unit cell and the second unit cell are both 100~150um, the height of the first P-region gate line is 10~20um, and the height of the first N-region gate line is 11~23um.

9. The photovoltaic bifacial cell as described in claim 1, characterized in that, The second surface and the third surface are provided with matching limiting protrusions and limiting grooves, and the limiting protrusions are provided on the outer edge of the second surface or the third surface.

10. The photovoltaic bifacial cell as described in claim 1, characterized in that, The first metal grid line includes a main grid line extending along a second direction, and a first sub-grid line and a second sub-grid line extending along a third direction. The first sub-grid line and the second sub-grid line are respectively disposed on both sides of the main grid line and connected to the main grid line. The first direction, the second direction, and the third direction are arranged to intersect each other.

11. The photovoltaic bifacial cell as described in claim 10, characterized in that, The width of the main gate line in the third direction is 200~500um, and the width of the first sub-gate line and the second sub-gate line in the second direction is 18~28um.

12. The photovoltaic bifacial cell as described in claim 10, characterized in that, In the second direction, the first sub-gate line of the main gate line is adjacent to and alternates with the second sub-gate line of the adjacent main gate line, and the second sub-gate line of the main gate line is adjacent to and alternates with the first sub-gate line of the adjacent main gate line.

13. The photovoltaic bifacial cell as described in claim 10, characterized in that, The second sub-grid line adjacent to the first sub-grid line in the second direction coincides with the projection portion of the first sub-grid line in the second direction.

14. The photovoltaic bifacial cell as described in claim 10, characterized in that, The projections of the first and second sub-grid lines of the same main grid line in a third direction are staggered.

15. A photovoltaic bifacial cell, characterized in that, It includes a first unit sheet and a second unit sheet, the first unit sheet and the second unit sheet are stacked together. In a first direction, the first unit sheet is provided with a first surface and a second surface, the second unit sheet is provided with a third surface and a fourth surface, the second surface and the third surface are opposite to each other and are connected by metallization through a metal layer. The first unit sheet is provided with a first metal grid line protruding towards the second surface, and the second unit sheet is provided with a second metal grid line protruding towards the third surface. The first surface of the first unit sheet and the fourth surface of the second unit sheet serve as the light-receiving surfaces of the entire photovoltaic bifacial cell, and neither of them has metal grid lines. The metal layer is formed by sintering the first metal grid line and the second metal grid line at high temperature.

16. The photovoltaic bifacial cell as described in claim 15, characterized in that, The first metal gate line includes a first P-region gate line and a first N-region gate line, and the second metal gate line includes a second P-region gate line and a second N-region gate line; In the first direction, the height of the first unit cell and the second unit cell are both 100um~150um, the height of the first P-region gate line and the second P-region gate line are both 5~10um, the height of the first N-region gate line and the second N-region gate line are both 6~11um, and the sum of the heights of the first P-region gate line and the second P-region gate line is 10~20um, and the sum of the heights of the first N-region gate line and the second N-region gate line is 12~23um.

17. The photovoltaic bifacial cell as described in claim 16, characterized in that, The side of the first P-region gate line that is away from the second surface and the side of the first N-region gate line that is away from the second surface are on the same plane; The side of the second P-region gate line that is away from the third surface and the side of the second N-region gate line that is away from the third surface are on the same plane.

18. The photovoltaic bifacial cell as described in claim 15, characterized in that, The first unit chip has a first grid groove on the second surface that is opposite to the first metal grid line. In a first direction, the projection of the first metal grid line and the projection of the first grid groove at least partially overlap. The second unit chip has a second grid groove on the third surface that is opposite to the second metal grid line, and in the first direction, the projection of the second metal grid line and the projection of the second grid groove at least partially overlap.

19. The photovoltaic bifacial cell as described in claim 18, characterized in that, The first metal gate line completely covers the first gate line slot, and the second metal gate line completely covers the second gate line slot; The projections of the first metal grid line and the second metal grid line in the first direction completely coincide, and the shapes of the first metal grid line and the second metal grid line are similar to the shape of the second grid line groove.

20. The photovoltaic bifacial cell as described in claim 15, characterized in that, The second surface and the third surface are provided with matching limiting protrusions and limiting grooves, and the limiting protrusions are provided on the outer edge of the second surface or the third surface.

21. The photovoltaic bifacial cell as described in claim 15, characterized in that, The first metal grid line includes a main grid line extending along a second direction, and a first sub-grid line and a second sub-grid line extending along a third direction. The first sub-grid line and the second sub-grid line are respectively disposed on both sides of the main grid line and connected to the main grid line. The first direction, the second direction, and the third direction are arranged to intersect each other.

22. The photovoltaic bifacial cell as described in claim 21, characterized in that, The width of the main gate line in the third direction is 200~500um, and the width of the first sub-gate line and the second sub-gate line in the second direction is 18~28um.

23. The photovoltaic bifacial cell as described in claim 21, characterized in that, In the second direction, the first sub-gate line of the main gate line is adjacent to and alternates with the second sub-gate line of the adjacent main gate line, and the second sub-gate line of the main gate line is adjacent to and alternates with the first sub-gate line of the adjacent main gate line.

24. The photovoltaic bifacial cell as described in claim 21, characterized in that, The second sub-grid line adjacent to the first sub-grid line in the second direction coincides with the projection portion of the first sub-grid line in the second direction.

25. The photovoltaic bifacial cell as described in claim 21, characterized in that, The projections of the first and second sub-grid lines of the same main grid line in a third direction are staggered.

26. A photovoltaic bifacial cell module, characterized in that, The photovoltaic bifacial cell according to any one of claims 1 to 14 is provided with a first conductive path and a second conductive path, wherein both the first conductive path and the second conductive path are connected to the metal layer. The first conductive path of the photovoltaic bifacial cell is connected to the second conductive path of the adjacent photovoltaic bifacial cell.

27. The photovoltaic bifacial cell module as described in claim 26, characterized in that, The first conductive path and the second conductive path are respectively located at the two ends of the photovoltaic bifacial cell in the second direction. The photovoltaic bifacial cell is mounted on an adjacent photovoltaic bifacial cell so that the first conductive path of the photovoltaic bifacial cell is connected to the second conductive path of the adjacent photovoltaic bifacial cell.

28. A photovoltaic bifacial cell module, characterized in that, The photovoltaic bifacial cell includes any one of claims 15 to 25, wherein the first unit cell is provided with a first conductive path, the second unit cell is provided with a second conductive path, the first conductive path is connected to the first metal grid line, and the second conductive path is connected to the second metal grid line.

29. The photovoltaic bifacial cell module as described in claim 28, characterized in that, The first surface has a first conductive groove, and the first conductive groove is at a preset distance from the second surface. The first conductive path is a conductive element disposed in the first conductive groove, and the conductive element is connected to the first metal grid line. The fourth surface has a second conductive groove, and the second conductive groove is at a preset distance from the third surface. The second conductive path is a second conductive element disposed in the second conductive groove, and the second conductive element is connected to the second metal grid line.

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