Back contact cell, back contact cell string and solar cell module

Abstract

The invention discloses a back contact cell, a back contact cell string and a solar cell module, the back contact cell comprises first doped regions, second doped regions and isolation regions, the first doped regions, the second doped regions and the isolation regions are arranged on a backlight surface of a semiconductor substrate, and the first doped regions and the second doped regions are alternately arranged along a first direction; the isolation region is arranged between the first doped region and the second doped region, and the doping types of the first doped region and the second doped region are opposite; the first side wall, close to the isolation region, of the first doping region protrudes towards the isolation region to form a first protruding region, and the first protruding region comprises a plurality of first protruding units arranged in the second direction; the second side wall, close to the isolation region, of the second doped region protrudes towards the isolation region to form a second protruding region, and the second protruding region comprises a plurality of second protruding units arranged in the second direction. According to the invention, carrier migration between the first doped region and the second doped region can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a back contact cell, a back contact cell string and a solar cell module. Background Art

[0002] Interdigitated Back Contact (IBC) is a high-efficiency solar cell technology. The positive and negative metal electrodes of the IBC cell are arranged in a cross-finger pattern on the backlight side of the cell. This design allows the front surface of the cell to be shielded by no metal grid lines, thereby maximizing the illuminated area and reducing optical losses, improving short-circuit current and overall photoelectric conversion efficiency. In order to prevent carriers from directly contacting the N-type doped region and the P-type doped region, resulting in the inability to effectively collect carriers, an isolation region needs to be set at the junction of the P-type doped region and the N-type doped region. The morphological characteristics of the isolation region will affect the performance of the IBC cell. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a back contact cell, a back contact cell string and a solar cell module to promote carrier migration between a first doping region and a second doping region.

[0004] In order to solve the above problems, the present invention discloses a back contact battery, comprising a first doping region, a second doping region and an isolation region arranged on the backlight surface of a semiconductor substrate, wherein the first doping region and the second doping region are alternately arranged along a first direction, the isolation region is arranged between the first doping region and the second doping region, and the first doping region and the second doping region have opposite doping types;

[0005] The first doped region is close to the first side wall of the isolation region and protrudes toward the isolation region to form a first protruding region, wherein the first protruding region includes a plurality of first protruding units arranged along the second direction;

[0006] The second doping region is close to the second side wall of the isolation region and protrudes toward the isolation region to form a second protruding region, and the second protruding region includes a plurality of second protruding units arranged along the second direction.

[0007] As an improvement of the above technical solution, the shape of the first protrusion unit is different from the shape of the second protrusion unit.

[0008] As an improvement of the above technical solution, the first protrusion unit and the second protrusion unit have different widths in the first direction;

[0009] And / or, the first protrusion unit and the second protrusion unit have different lengths in the second direction.

[0010] As an improvement of the above technical solution, the first raised area includes periodically repeated first raised units, the first raised units protrude toward the isolation area to form a first raised portion, and the first raised portion includes a straight line portion; the second raised area includes periodically repeated second raised units, the second raised units protrude toward the isolation area to form a second raised portion, and the second raised unit includes an arc portion.

[0011] As an improvement of the above technical solution, the width of the first protrusion unit in the first direction is H1, and H1 is 5 μm to 195 μm.

[0012] As an improvement of the above technical solution, the width of the second protrusion unit in the first direction is H2, and H2≥H1.

[0013] As an improvement of the above technical solution, the H2 is 5 μm to 195 μm.

[0014] As an improvement of the above technical solution, the length of the first protrusion unit in the second direction is D1, and D1 is 40 μm to 500 μm.

[0015] As an improvement of the above technical solution, the length of the second protrusion unit in the second direction is D2, and D2≤D1.

[0016] As an improvement of the above technical solution, the D2 is 40 μm to 500 μm.

[0017] As an improvement of the above technical solution, the first protruding area includes periodically repeated first protruding units, the first protruding units protrude toward the first doping area to form a first protruding portion, and the first protruding portion includes a first straight line portion and a second straight line portion connected in sequence.

[0018] As an improvement of the above technical solution, the first protruding area includes periodically repeated first protruding units, the first protruding units protrude toward the first doping area to form a first protruding portion, and the first protruding portion includes a first arc portion, a first straight portion and a second straight portion connected in sequence.

[0019] As an improvement of the above technical solution, a preset angle α1 is formed between the first straight portion and the second direction, and a preset angle α2 is formed between the second straight portion and the second direction, and α1≥α2.

[0020] As an improvement of the above technical solution, the α1 is 30° to 87°, and the α2 is 3° to 42°.

[0021] As an improvement of the above technical solution, the second protruding area includes periodically repeated second protruding units, the second protruding units protrude toward the second doping area to form a second protruding portion, and the second protruding portion includes a second arc-shaped portion and a third arc-shaped portion.

[0022] As an improvement of the above technical solution, the two ends of the second arc portion are respectively the first endpoint and the second endpoint, the second arc portion is recessed toward the second doping region, and a preset angle α3 is formed between a line connecting the first endpoint and the second endpoint and the second direction; the two ends of the third arc portion are respectively the third endpoint and the fourth endpoint, the third arc portion is recessed toward the second doping region, and a preset angle α4 is formed between a line connecting the third endpoint and the fourth endpoint and the second direction, α3≤α4.

[0023] As an improvement of the above technical solution, the second protruding area includes periodically repeated second protruding units, the second protruding units protrude toward the second doping area to form a second protruding portion, and the second protruding portion includes a third straight portion and a third arc portion.

[0024] As an improvement of the above technical solution, a preset angle α3 is provided between the third straight portion and the second direction, two ends of the third arc portion are respectively a third endpoint and a fourth endpoint, the third arc portion is recessed toward the second doping region, and a preset angle α4 is provided between a line connecting the third endpoint and the fourth endpoint and the second direction, α3≤α4.

[0025] As an improvement of the above technical solution, the angle α3 is 15° to 40°, and the angle α4 is 25° to 50°.

[0026] As an improvement of the above technical solution, along the first direction, the width of the isolation region is 20 μm to 200 μm.

[0027] Correspondingly, the present invention also discloses a back-contact battery string, including the above-mentioned back-contact battery.

[0028] Correspondingly, the present invention also discloses a solar cell assembly, comprising the above-mentioned back contact cell string.

[0029] The implementation of the present invention has the following beneficial effects:

[0030] 1. In the present invention, a first raised region is provided on a side wall of the first doped region near the isolation region, and a second raised region is provided on a side wall of the second doped region near the isolation region. The provision of the first raised region and the second raised region can shorten the distance between the first doped region and the second doped region, and promote the migration of carriers between the first doped region and the second doped region; in addition, the provision of the first raised region and the second raised region also increases the contact area between the first doped region and the second doped region and the subsequently deposited passivation layer, thereby improving the passivation performance of the back contact battery.

[0031] 2. The first protrusion unit and the second protrusion unit of the present invention have different shapes. The first protrusion unit and the second protrusion unit of different shapes are set for the first doping region and the second doping region with different doping types, which is beneficial to the carrier migration between the first doping region and the second doping region, reduces the carrier recombination rate of the first doping region and the second doping region near the isolation region, and further improves the working performance of the back contact battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic structural diagram of a longitudinal end surface of a back contact battery provided by an embodiment of the present invention;

[0033] Figure 2 is a schematic structural diagram of a back contact battery provided in Example 1 of the present invention;

[0034] Figure 3 is a schematic structural diagram of a back contact battery provided in Example 2 of the present invention;

[0035] Figure 4 It is a schematic diagram of the structure of the back contact battery provided in Example 2 of the present invention.

[0036] Figure 5 is a schematic structural diagram of a back contact battery provided by Example 9 of the present invention;

[0037] Figure 6 It is a schematic diagram of the structure of the back contact battery provided in Example 9 of the present invention. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in further detail below.

[0039] See also Figure 1 and Figure 2 The present invention provides a back contact battery, comprising a first doping region 11, a second doping region 12 and an isolation region 13 arranged on the back of a semiconductor substrate 1, wherein the first doping region 11 and the second doping region 12 are arranged alternately, and the isolation region 13 is arranged between the first doping region 11 and the second doping region 12, and the doping type of the first doping region 11 is the same as or opposite to the doping type of the semiconductor substrate 1, and the doping types of the first doping region 11 and the second doping region 12 are opposite, for example, the semiconductor substrate is an N-type semiconductor substrate, the first doping region is a P-type doping region, and the second doping region is an N-type doping region, and a PN junction is formed between the first doping region and the semiconductor substrate to effectively shunt carriers. The setting of the isolation region 13 can reduce the carrier recombination rate at the lateral junction of the first doping region and the second doping region, which is conducive to improving the photoelectric conversion efficiency of the back contact battery.

[0040] The first doping region 11 is close to the first side wall 111 of the isolation region 13 and protrudes toward the isolation region 13 to form a first protruding region 112, and the first protruding region 112 includes a plurality of first protruding units 113 arranged along the second direction. The second doping region 12 is close to the second side wall 121 of the isolation region 13 and protrudes toward the isolation region 13 to form a second protruding region 122, and the second protruding region 122 includes a plurality of second protruding units 123 arranged along the second direction.

[0041] Compared with the existing method of setting the first side wall 111 and the second side wall 121 as a flat surface without undulations, the formation of the first raised area 112 and the second raised area 122 of the present invention can prevent the reduction of the carrier mobility between the first doping area 11 and the second doping area 12 due to the excessively large distance between the first doping area 11 and the second doping area 12. At the same time, the setting of the first raised area 112 and the second raised area 122 can also ensure that the first doping area 11 and the second doping area 12 will not cause leakage due to the connection, thereby ensuring the electrical reliability of the back contact battery and improving the carrier mobility between the first doping area 11 and the second doping area 12; in addition, the setting of the first raised area 112 and the second raised area 122 also increases the contact area between them and the subsequently deposited passivation layer, thereby improving the passivation performance of the back contact battery.

[0042] Exemplarily, when the semiconductor substrate 1 is an N-type semiconductor substrate, the first doped region 11 is a P-type emitter, and the second doped region 12 is an N-type back surface field. The minority holes in the photogenerated electron-hole pairs of the semiconductor substrate 1 directly above the P-type emitter can be directly vertically transported to the P-type emitter under the action of the built-in electric field, while the holes in the semiconductor substrate 1 directly above the isolation region 13 and the N-type back surface field need to be laterally transported to the P-type emitter to be collected. Similarly, the majority electrons in the photogenerated electron-hole pairs directly above the N-type back surface field can be directly vertically transported to the N-type back surface field, while the electrons in the isolation region 13 and the P-type emitter need to be laterally transported to the back surface field to be collected, thereby generating a photogenerated electromotive force between the P-type emitter and the N-type back surface field.

[0043] Optional, such as Figure 3As shown, the shapes of the first protrusion unit 113 and the second protrusion unit 123 can be arc-shaped, triangular, quadrilateral, etc., as long as they protrude toward the isolation region. In some embodiments, the shape of the first protrusion unit 113 is different from the shape of the second protrusion unit 123. Specifically, the first protrusion region 112 includes periodically repeated first protrusion units 113, the first protrusion units 113 protrude toward the first doping region 11 to form a first protrusion portion 114, and the first protrusion portion 114 includes a straight line portion; the second protrusion region 122 includes periodically repeated second protrusion units 123, the second protrusion units 123 protrude toward the second doping region 12 to form a second protrusion portion 124, and the second protrusion unit 124 includes an arc-shaped portion. Specifically, the shape of the first protrusion unit 113 can be a triangle composed of straight line portions, or a quasi-triangle composed of straight line portions and arc-shaped portions, that is, at least one angle is an arc-shaped portion and / or at least one side is an arc-shaped portion. The shape of the second protrusion unit 123 can be an arc, wherein the arc can be a circular arc, an elliptical arc, any arc formed by deviation or bending from a straight line or a horizontal line, or a combination of an arc portion and a straight line portion. The types of carriers migrating from the first doping region 11 to the second doping region 12 and the types of carriers migrating from the second doping region 12 to the first doping region 11 are different, and the mobility of the carriers is also different, so the first protrusion unit 113 and the second protrusion unit 123 are set to different shapes to balance the mobility of different types of carriers.

[0044] Optionally, in some embodiments, the widths of the first protrusion unit 113 and the second protrusion unit 123 in the first direction are different. The width of the first protrusion unit 113 in the first direction is H1, and H1 is 5μm to 195μm, and is exemplarily 25μm, 50μm, 100μm, 120μm or 160μm, but not limited thereto. The width of the second protrusion unit 123 in the first direction is H2. H2 is 5μm to 195μm, and is exemplarily 25μm, 50μm, 100μm, 120μm or 160μm, but not limited thereto. If the width is less than 5μm, the transmission of carriers is affected, resulting in an increase in recombination loss; if the width is greater than 195μm, it is easy to cause the first doped region and the second doped region to be connected, resulting in the occurrence of a short circuit. Preferably, H2≥H1, and more preferably, H2 and H1 satisfy the following formula, H2=(1.2~2)H1. By controlling the width H1 of the first protrusion unit 113 and the width H2 of the second protrusion unit 123 within a preferred ratio range, the carrier transmission rate can be increased while further reducing the recombination loss on the first sidewall 111 and the second sidewall 121 .

[0045] Optionally, in some embodiments, the lengths of the first protrusion unit 113 and the second protrusion unit 123 in the second direction are different. The length of the first protrusion unit 113 in the second direction is D1, and D1 is 40μm to 500μm, and is exemplarily 50μm, 100μm, 200μm, 300μm or 400μm, but not limited thereto. The length of the second protrusion unit 123 in the second direction is D2. The D2 is 40μm to 500μm, and is exemplarily 50μm, 100μm, 200μm, 300μm or 400μm, but not limited thereto. If the length is less than 40μm, the preparation complexity is increased while the damage to the sidewall is increased; if the length is greater than 500μm, the transport effect of the carrier is affected. Preferably, D2≤D1, and more preferably, D2 and D1 satisfy the following formula, D2=(0.65~0.85)D1. By controlling the length D1 of the first protrusion unit 113 and the length D2 of the second protrusion unit 123 within a preferred ratio range, the carrier mobility can be improved while further reducing the recombination loss on the first sidewall 111 and the second sidewall 121. The first direction is different from the second direction. Specifically, the first direction is the direction in which the first doping regions 11 and the second doping regions 12 are alternately arranged, that is, the width direction of the isolation region 13. The second direction is the extension direction of the first doping regions 11 and the second doping regions 12, that is, the length direction of the isolation region 13. The first direction and the second direction are perpendicular.

[0046] Specifically, Figure 3 and Figure 4 As shown, in one embodiment, the first raised area 112 includes a first raised unit 113 that is repeated periodically, and the first raised unit 113 is raised toward the first doped area 11 to form a first raised portion 114, and the first raised portion 114 includes a first straight portion 114b and a second straight portion 114c that are connected in sequence. Among them, there is a preset angle α1 between the first straight portion 114b and the second direction, and there is a preset angle α2 between the second straight portion 114c and the second direction, α1≥α2, specifically, the α1 is 30° to 87°, and is exemplarily 35°, 45°, 55°, 65° or 75°, but not limited thereto. The α2 is 3° to 42°, and is exemplarily 5°, 15°, 20°, 30° or 35°, but not limited thereto. This structure can improve the diversion effect of the liquid required for subsequent cleaning, thereby improving the surface quality of the first raised area, and the passivation effect of the subsequent deposited back passivation layer is good, which is conducive to the improvement of the open circuit voltage.

[0047] like Figure 5 and Figure 6As shown, in a preferred embodiment, the first raised area 112 includes periodically repeated first raised units 113, the first raised units 113 are raised toward the first doped area 11 to form a first raised portion 114, and the first raised portion 114 includes a first arc portion 114a, a first straight portion 114b and a second straight portion 114c connected in sequence. The provision of the first arc portion 114a can further improve the guiding effect of the drug solution, thereby improving the surface quality of the first raised area.

[0048] like Figure 3 and Figure 4 As shown, in one embodiment, the second convex area 122 includes a periodically repeated second convex unit 123, the second convex unit 123 convexes toward the second doping area 12 to form a second convex portion 124, and the second convex portion 124 includes a second arc portion 124a and a third arc portion 124b. The two ends of the second arc portion 124a are respectively a first end point and a second end point, the second arc portion 124a is formed by being recessed toward the second doping area 12, and a preset angle α3 is formed between the line connecting the first end point and the second end point and the second direction; the two ends of the third arc portion 124b are respectively a third end point and a fourth end point, the third arc portion 124b is formed by being recessed toward the second doping area 12, and a preset angle α4 is formed between the line connecting the third end point and the fourth end point and the second direction, α3≤α4. Specifically, α3 is 15° to 40°, and is exemplarily 20°, 24°, 28°, 30° or 35°, but is not limited thereto. The angle α4 is 25° to 50°, and is exemplarily 30°, 35°, 40°, 42° or 45°, but is not limited thereto. This structure can improve the surface quality of the second raised area, and the passivation effect of the subsequently deposited back passivation layer is good.

[0049] In a preferred embodiment, Figure 5 and Figure 6As shown, the second convex area 122 includes a periodically repeated second convex unit 123, the second convex unit 123 convexes toward the second doping area 12 to form a second convex portion 124, and the second convex portion 124 includes a third straight portion 124c and a third arc portion 124b. There is a preset angle α3 between the third straight portion 124c and the second direction, the two ends of the third arc portion 124b are respectively a third endpoint and a fourth endpoint, and the third arc portion 124b is recessed toward the second doping area 12, and there is a preset angle α4 between the line connecting the third endpoint and the fourth endpoint and the second direction, α3≤α4. Specifically, α3 is 15° to 40°, and is exemplarily 20°, 24°, 28°, 30° or 35°, but not limited thereto. α4 is 25° to 50°, and is exemplarily 30°, 35°, 40°, 42° or 45°, but not limited thereto. The provision of the third straight portion 124c can improve the surface quality of the second convex area, and the passivation effect of the subsequently deposited back passivation layer is good.

[0050] It can be understood that the first protrusion unit 113 and the second protrusion unit 123 can be obtained by laser processing and / or wet etching. For example, the first side wall 111 and the second side wall 121 of the present invention are obtained by laser processing. Compared with a flat surface without undulations, during the laser processing, the preparation of the first side wall 111 having the first protrusion structure 112 and the second side wall 121 having the second protrusion structure 122 has lower requirements on the shape and size of the laser processing spot. Specifically, by adjusting the laser pulse period, spot size, inclination angle and other process parameters, the first protrusion unit 113 and the second protrusion unit 123 with different shapes can be obtained.

[0051] In addition, along the first direction, the width L1 of the isolation region 13 is 20μm to 200μm, and is exemplarily 30μm, 50μm, 80μm, 120μm or 160μm, but not limited thereto. It is understandable that the width L1 of the isolation region 13 refers to the minimum distance between the first raised region 112 and the second raised region 122 in the first direction. If the width L1 of the isolation region 13 is too small, it is difficult to ensure the isolation effect between the first doping region 11 and the second doping region 12; if the width L2 of the isolation region 13 is too large, the lateral transport distance of the carriers becomes larger, the series distribution resistance of the battery lateral space increases, and the recombination probability of electrons and holes also increases, which makes the short-circuit current, open-circuit voltage and fill factor decrease, resulting in a decrease in the efficiency of the back contact battery.

[0052] It can be understood that the first doping region 11 and the second doping region 12 are arranged on the semiconductor substrate 1. Optionally, the first doping region 11 can be located in the semiconductor substrate 1, or in a partial area of ​​the backlight surface of the semiconductor substrate 1, and the second doping region 12 can be located in the semiconductor substrate 1, or in a partial area of ​​the backlight surface of the semiconductor substrate 1. The first doping region 11 and the second doping region 12 can be rectangular strip regions, wavy strip regions, etc. that match the morphology of the electrode structure printed thereon, and no specific limitation is made here. In addition, for the first doping region 11 and the second doping region 12, since the range of the first doping region 11 and the second doping region 12 affects the junction area range of the PN junction in the back contact battery, and thus affects the strength of the built-in electric field in the back contact battery, the area ratio between the first doping region 11 and the second doping region 12 can be determined according to the requirements for the junction area range of the PN junction in the actual application scenario, and no specific limitation is made here.

[0053] Specifically, the material of the semiconductor substrate 1 may be a semiconductor material such as silicon, silicon germanium, germanium or gallium arsenide. When the first doped region 11 is formed on a partial area of ​​the backlight surface of the semiconductor substrate 1, the first doped region 11 includes a first doped semiconductor layer, and the material of the first doped semiconductor layer may be a semiconductor material such as silicon, silicon germanium, germanium or gallium arsenide; the crystal orientation of the first doped semiconductor layer may be amorphous, nanocrystalline, microcrystalline, single crystal or polycrystalline, etc. When the second doped region 12 is formed on a partial area of ​​the backlight surface of the semiconductor substrate 1, the second doped region includes a second doped semiconductor layer, and the material of the second doped semiconductor layer may be a semiconductor material such as silicon, silicon germanium, germanium or gallium arsenide; the crystal orientation of the second doped semiconductor layer may be amorphous, nanocrystalline, microcrystalline, single crystal or polycrystalline, etc. The materials of the first doped semiconductor layer and the second doped semiconductor layer may be the same or different, and are not specifically limited here.

[0054] In a preferred embodiment, a first tunneling layer is formed between the first doped semiconductor layer and the semiconductor substrate 1 , and / or a second tunneling layer is formed between the second doped semiconductor layer and the semiconductor substrate 1 .

[0055] The material of the first tunneling layer and / or the second tunneling layer may be silicon oxide, aluminum oxide, titanium oxide, or the like.

[0056] The provision of the passivation layer can reduce the recombination of surface carriers. The passivation layer covers the first doped region 11, the first doped region 12 and the isolation region 13. The passivation layer can passivate the side of the first doped conductive layer and the second doped conductive layer away from the semiconductor substrate 1, reduce the carrier recombination rate on the side of the first doped conductive layer and the second doped conductive layer away from the semiconductor substrate 1, and further improve the photoelectric conversion efficiency of the back contact battery. The passivation layer can be one or more of an aluminum oxide layer, a silicon nitride layer, a silicon oxide layer, and a silicon oxynitride layer. Preferably, the passivation layer includes an aluminum oxide layer and a silicon nitride layer stacked in sequence.

[0057] In addition to the above structure, the back contact battery also includes a first electrode and a second electrode. The first electrode penetrates the passivation layer and is electrically connected to the first doping region 11; the second electrode penetrates the passivation layer and is electrically connected to the second doping region 12. The first electrode and the second electrode are fine grids (sub-grids) of the solar cell, which are used to collect and aggregate the current of the solar cell. The first electrode and the second electrode can be sintered by a burn-through slurry or a non-burn-through slurry. The material of the first electrode and the second electrode can be one or more of aluminum, silver, gold, nickel, molybdenum or copper.

[0058] Correspondingly, an embodiment of the present invention further provides a solar cell string, including the above-mentioned solar cells, each solar cell string includes a plurality of solar cells connected in series, and the plurality of solar cells can be partially overlapped to form a solar cell string, and the contact area between the overlaps is not conductively connected, that is, no conductive glue or other adhesive is required between the overlapped areas, and the solar cells are simply overlapped together. Optionally, the solar cell can be a whole-piece back contact cell, or a sliced ​​back contact cell (such as a half-sliced ​​back contact cell or a third-sliced ​​back contact cell, etc.). Among them, the above-mentioned whole-piece back contact cell can be a whole-piece cell that does not require slice processing; or, the above-mentioned whole-piece back contact cell can also include at least two slice units with a symmetrical electrode design; or, the above-mentioned whole-piece back contact cell can also include at least two slice units with an asymmetric electrode design. The overlapping areas of adjacent solar cells in the solar cell string are provided with series welding strips to fix the adjacent solar cells, and the series welding strips connect the adjacent solar cells in series. Different solar cell strings are obtained by series connection and / or parallel connection.

[0059] Correspondingly, an embodiment of the present invention further provides a solar cell assembly, including the above-mentioned solar cell string. The solar cell assembly may also include a metal frame, a back plate, a photovoltaic glass and an adhesive film. The adhesive film may be filled between the front and back of the solar cell string, the photovoltaic glass, the back plate, etc. The adhesive film may be a transparent colloid with good light transmittance and aging resistance, such as an EVA adhesive film or a POE adhesive film, which may be selected according to actual conditions and is not specifically limited here.

[0060] Photovoltaic glass can cover the front of the solar cell string. Photovoltaic glass can be ultra-white glass, which has high light transmittance, high transparency, and excellent physical, mechanical and optical properties. For example, the light transmittance of ultra-white glass can reach more than 92%, which can protect the solar cell string without affecting its efficiency as much as possible. At the same time, the adhesive film can bond the photovoltaic glass and the solar cell string together. The presence of the adhesive film can seal and insulate the solar cell string to achieve waterproof and moisture-proof.

[0061] The backplane can be attached to the back of the solar cell string. The backplane can protect and support the solar cell string. The backplane has reliable insulation, water resistance and aging resistance. The backplane can be tempered glass, organic glass, aluminum alloy TPT composite film, etc., which can be selected according to actual conditions and are not specifically limited here. The whole composed of the backplane, solar cell string, film and photovoltaic glass can be set on a metal frame. The metal frame serves as the main external support structure of the entire solar cell assembly and provides stable support and installation for the solar cell assembly.

[0062] The present invention will be further described below with specific embodiments:

[0063] Example 1

[0064] This embodiment provides a back-contact battery, including an N-type doped region, a P-type doped region and an isolation region arranged on the back side of an N-type silicon substrate, the N-type doped region and the P-type doped region are alternately arranged, and the isolation region is arranged between the N-type doped region and the P-type doped region.

[0065] The first side wall of the P-type doped region near the isolation region protrudes toward the isolation region to form a first protruding region, and the first protruding region includes a plurality of first protruding units arranged along the second direction; the second side wall of the N-type doped region near the isolation region protrudes toward the isolation region to form a second protruding region, and the second protruding region includes a plurality of second protruding units arranged along the second direction. The first protruding unit protrudes toward the isolation region to form a first protruding portion, and the shape of the first protruding portion is a triangle, and the length of the two sides of the triangle is equal. Along the first direction, the width of the first protruding portion is 30μm; along the second direction, the length of the first protruding portion is 400μm. The second protruding unit protrudes toward the isolation region to form a second protruding portion, and the shape of the second protruding portion is a triangle, and the length of the two sides of the triangle is equal. Along the first direction, the width of the second protruding portion is 30μm, and along the second direction, the length of the second protruding portion is 400μm.

[0066] Example 2

[0067] This embodiment provides a back-contact battery, including an N-type doped region, a P-type doped region and an isolation region arranged on the back side of an N-type silicon substrate, the N-type doped region and the P-type doped region are alternately arranged, and the isolation region is arranged between the N-type doped region and the P-type doped region.

[0068] The first side wall of the P-type doped region near the isolation region protrudes toward the isolation region to form a first protruding region, and the first protruding region includes a plurality of first protruding units arranged along the second direction; the second side wall of the N-type doped region near the isolation region protrudes toward the isolation region to form a second protruding region, and the second protruding region includes a plurality of second protruding units arranged along the second direction. The first protruding unit protrudes toward the isolation region to form a first protruding portion, and the shape of the first protruding portion is a triangle, and the two sides of the triangle are equal in length. Along the first direction, the width of the first protruding portion is 30μm; along the second direction, the length of the first protruding portion is 400μm. The second protruding unit protrudes toward the isolation region to form a second protruding portion, and the shape of the second protruding portion is two symmetrical arcs. Along the first direction, the width of the second protruding portion is 30μm, and along the second direction, the length of the second protruding portion is 400μm.

[0069] Example 3

[0070] This embodiment provides a back-contact battery, including an N-type doped region, a P-type doped region and an isolation region arranged on the back side of an N-type silicon substrate, the N-type doped region and the P-type doped region are alternately arranged, and the isolation region is arranged between the N-type doped region and the P-type doped region.

[0071] The first side wall of the P-type doped region near the isolation region protrudes toward the isolation region to form a first protruding region, and the first protruding region includes a plurality of first protruding units arranged along the second direction; the second side wall of the N-type doped region near the isolation region protrudes toward the isolation region to form a second protruding region, and the second protruding region includes a plurality of second protruding units arranged along the second direction. The first protruding unit protrudes toward the isolation region to form a first protruding portion, and the shape of the first protruding portion is a triangle, and the two sides of the triangle are equal in length. Along the first direction, the width of the first protruding portion is 30μm; along the second direction, the length of the first protruding portion is 400μm. The second protruding unit protrudes toward the isolation region to form a second protruding portion, and the shape of the second protruding portion is two symmetrical arcs. Along the first direction, the width of the second protruding portion is 30μm, and along the second direction, the length of the second protruding portion is 300μm.

[0072] Example 4

[0073] This embodiment provides a back-contact battery, including an N-type doped region, a P-type doped region and an isolation region arranged on the back side of an N-type silicon substrate, the N-type doped region and the P-type doped region are alternately arranged, and the isolation region is arranged between the N-type doped region and the P-type doped region.

[0074] The first side wall of the P-type doped region near the isolation region protrudes toward the isolation region to form a first protruding region, and the first protruding region includes a plurality of first protruding units arranged along the second direction; the second side wall of the N-type doped region near the isolation region protrudes toward the isolation region to form a second protruding region, and the second protruding region includes a plurality of second protruding units arranged along the second direction. The first protruding unit protrudes toward the isolation region to form a first protruding portion, and the shape of the first protruding portion is a triangle, and the two sides of the triangle are equal in length. Along the first direction, the width of the first protruding portion is 30μm; along the second direction, the length of the first protruding portion is 400μm. The second protruding unit protrudes toward the isolation region to form a second protruding portion, and the shape of the second protruding portion is two symmetrical arcs. Along the first direction, the width of the second protruding portion is 40μm, and along the second direction, the length of the second protruding portion is 400μm.

[0075] Example 5

[0076] This embodiment provides a back-contact battery, including an N-type doped region, a P-type doped region and an isolation region arranged on the back side of an N-type silicon substrate, the N-type doped region and the P-type doped region are alternately arranged, and the isolation region is arranged between the N-type doped region and the P-type doped region.

[0077] The first side wall of the P-type doped region near the isolation region protrudes toward the isolation region to form a first protruding region, and the first protruding region includes a plurality of first protruding units arranged along the second direction; the second side wall of the N-type doped region near the isolation region protrudes toward the isolation region to form a second protruding region, and the second protruding region includes a plurality of second protruding units arranged along the second direction. The first protruding unit protrudes toward the isolation region to form a first protruding portion, and the shape of the first protruding portion is a triangle, and the two sides of the triangle are equal in length. Along the first direction, the width of the first protruding portion is 30μm; along the second direction, the length of the first protruding portion is 400μm. The second protruding unit protrudes toward the isolation region to form a second protruding portion, and the shape of the second protruding portion is two symmetrical arcs. Along the first direction, the protrusion of the second protruding portion is 40μm, and along the second direction, the length of the second protruding portion is 300μm.

[0078] Example 6

[0079] This embodiment provides a back-contact battery, including an N-type doped region, a P-type doped region and an isolation region arranged on the back side of an N-type silicon substrate, the N-type doped region and the P-type doped region are alternately arranged, and the isolation region is arranged between the N-type doped region and the P-type doped region.

[0080] The first side wall of the P-type doped region near the isolation region protrudes toward the isolation region to form a first protruding region, and the first protruding region includes a plurality of first protruding units arranged along the second direction; the second side wall of the N-type doped region near the isolation region protrudes toward the isolation region to form a second protruding region, and the second protruding region includes a plurality of second protruding units arranged along the second direction. The first protruding unit protrudes toward the isolation region to form a first protruding portion, and the first protruding portion includes a first straight portion and a second straight portion connected in sequence. Along the first direction, the width of the first protruding portion is 30μm; along the second direction, the length of the first protruding portion is 300μm, the angle between the first straight portion and the second direction is 45°, and the angle between the second straight portion and the second direction is 15°. The second protruding unit protrudes toward the isolation region to form a second protruding portion, and the shape of the second protruding portion is two symmetrical arcs. Along the first direction, the protrusion of the second protruding portion is 40μm, and along the second direction, the length of the second protruding portion is 300μm.

[0081] Example 7

[0082] This embodiment provides a back-contact battery, including an N-type doped region, a P-type doped region and an isolation region arranged on the back side of an N-type silicon substrate, the N-type doped region and the P-type doped region are alternately arranged, and the isolation region is arranged between the N-type doped region and the P-type doped region.

[0083] The first side wall of the P-type doped region near the isolation region protrudes toward the isolation region to form a first protruding region, and the first protruding region includes a plurality of first protruding units arranged along the second direction; the second side wall of the N-type doped region near the isolation region protrudes toward the isolation region to form a second protruding region, and the second protruding region includes a plurality of second protruding units arranged along the second direction. The first protruding unit protrudes toward the isolation region to form a first protruding portion, and the shape of the first protruding portion is a triangle, and the lengths of the two sides of the triangle are equal. Along the first direction, the width of the first protruding portion is 30μm; along the second direction, the length of the first protruding portion is 400μm. The second protruding unit protrudes toward the isolation region to form a second protruding portion, and the second protruding portion includes a second arc-shaped portion and a third arc-shaped portion connected in sequence, along the first direction, the width of the second protruding portion is 40μm, along the second direction, the length of the second protruding portion is 300μm, the angle between the line connecting the two end points of the second arc-shaped portion and the second direction is 20°, and the angle between the line connecting the two end points of the third arc-shaped portion and the second direction is 40°.

[0084] Example 8

[0085] This embodiment provides a back-contact battery, including an N-type doped region, a P-type doped region and an isolation region arranged on the back side of an N-type silicon substrate, the N-type doped region and the P-type doped region are alternately arranged, and the isolation region is arranged between the N-type doped region and the P-type doped region.

[0086] The first side wall of the P-type doped region near the isolation region protrudes toward the isolation region to form a first protruding region, and the first protruding region includes a plurality of first protruding units arranged along the second direction; the second side wall of the N-type doped region near the isolation region protrudes toward the isolation region to form a second protruding region, and the second protruding region includes a plurality of second protruding units arranged along the second direction. The first protruding unit protrudes toward the isolation region to form a first protruding portion, and the first protruding portion includes a first straight portion and a second straight portion connected in sequence. Along the first direction, the width of the first protruding portion is 30μm; along the second direction, the length of the first protruding portion is 300μm, the angle between the first straight portion and the second direction is 45°, and the angle between the second straight portion and the second direction is 15°. The second protrusion unit protrudes toward the isolation area to form a second protrusion portion, and the second protrusion portion includes a second arc portion and a third arc portion connected in sequence. Along the first direction, the width of the second protrusion portion is 40μm, and along the second direction, the length of the second protrusion portion is 300μm. The angle between the line connecting the two end points of the second arc portion and the second direction is 20°, and the angle between the line connecting the two end points of the third arc portion and the second direction is 40°.

[0087] Example 9

[0088] This embodiment provides a back-contact battery, including an N-type doped region, a P-type doped region and an isolation region arranged on the back side of an N-type silicon substrate, the N-type doped region and the P-type doped region are alternately arranged, and the isolation region is arranged between the N-type doped region and the P-type doped region.

[0089] The first side wall of the P-type doped region near the isolation region protrudes toward the isolation region to form a first protruding region, and the first protruding region includes a plurality of first protruding units arranged along the second direction; the second side wall of the N-type doped region near the isolation region protrudes toward the isolation region to form a second protruding region, and the second protruding region includes a plurality of second protruding units arranged along the second direction. The first protruding unit protrudes toward the isolation region to form a first protruding portion, and the first protruding portion includes a first arc portion, a first straight portion, and a second straight portion connected in sequence. Along the first direction, the width of the first protruding portion is 30μm; along the second direction, the length of the first protruding portion is 400μm, the angle between the first straight portion and the second direction is 45°, and the angle between the second straight portion and the second direction is 15°. The second protrusion unit protrudes toward the isolation area to form a second protrusion portion, and the second protrusion portion includes a third straight line portion and a third arc portion connected in sequence. Along the first direction, the width of the second protrusion portion is 40μm, and along the second direction, the length of the second protrusion portion is 400μm. The angle between the third straight line portion and the second direction is 20°, and the angle between the line connecting the two end points of the third arc portion and the second direction is 40°.

[0090] The back contact battery electrodes prepared in Examples 1 to 9 were printed, sintered, alloyed, and then annealed to obtain finished solar cells. The performance of the finished solar cells was measured, and the results are shown in the following table:

[0091]

[0092] The above is a preferred embodiment of the invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the invention. These improvements and modifications are also considered to be within the scope of protection of the invention.

Claims

1. A back contact battery, characterized in that: It comprises a first doping region, a second doping region and an isolation region arranged on the backlight surface of the semiconductor substrate, wherein the first doping region and the second doping region are alternately arranged along a first direction, the isolation region is arranged between the first doping region and the second doping region, and the first doping region and the second doping region have opposite doping types; The first doped region is close to the first side wall of the isolation region and protrudes toward the isolation region to form a first protruding region, wherein the first protruding region includes a plurality of first protruding units arranged along the second direction; The second doping region is close to the second side wall of the isolation region and protrudes toward the isolation region to form a second protruding region, and the second protruding region includes a plurality of second protruding units arranged along the second direction.

2. The back contact cell according to claim 1, characterized in that A shape of the first protrusion unit is different from a shape of the second protrusion unit.

3. The back contact cell according to claim 2, characterized in that The first protrusion unit and the second protrusion unit have different widths in the first direction; And / or, the first protrusion unit and the second protrusion unit have different lengths in the second direction.

4. The back contact cell according to claim 2, characterized in that The first raised area includes periodically repeated first raised units, which are raised toward the isolation area to form a first raised portion, and the first raised portion includes a straight portion; the second raised area includes periodically repeated second raised units, which are raised toward the isolation area to form a second raised portion, and the second raised unit includes an arc portion.

5. The back contact cell according to claim 1, characterized in that The width of the first protrusion unit in the first direction is H1, and the H1 is 5 μm to 195 μm.

6. The back contact cell according to claim 5, characterized in that The width of the second protrusion unit in the first direction is H2, and H2≥H1.

7. The back contact cell according to claim 6, characterized in that The H2 is 5 μm to 195 μm.

8. The back contact cell according to claim 1, characterized in that The length of the first protrusion unit in the second direction is D1, and the D1 is 40 μm to 500 μm.

9. The back contact cell according to claim 8, characterized in that A length of the second protrusion unit in the second direction is D2, where D2≤D1.

10. The back contact cell according to claim 9, characterized in that The D2 is 40 μm to 500 μm.

11. The back contact cell according to claim 4, characterized in that The first protruding region includes periodically repeated first protruding units, the first protruding units protrude toward the first doping region to form a first protruding portion, and the first protruding portion includes a first straight portion and a second straight portion connected in sequence.

12. The back contact cell according to claim 4, characterized in that The first protruding region includes periodically repeated first protruding units, the first protruding units protrude toward the first doping region to form a first protruding portion, and the first protruding portion includes a first arc portion, a first straight portion, and a second straight portion connected in sequence.

13. The back contact cell according to claim 11 or 12, characterized in that: A preset angle α1 is formed between the first straight line portion and the second direction, and a preset angle α2 is formed between the second straight line portion and the second direction, and α1≥α2.

14. The back contact cell according to claim 13, characterized in that The α1 is 30° to 87°, and the α2 is 3° to 42°.

15. The back contact cell according to claim 4, characterized in that The second convex region includes periodically repeated second convex units, the second convex units protrude toward the second doping region to form a second convex portion, and the second convex portion includes a second arc-shaped portion and a third arc-shaped portion.

16. The back contact cell according to claim 15, characterized in that Two ends of the second arc portion are respectively a first end point and a second end point, the second arc portion is recessed toward the second doping region, and a line connecting the first end point and the second end point and the second direction form a preset angle α3; The two ends of the third arc portion are respectively a third endpoint and a fourth endpoint. The third arc portion is recessed toward the second doping region. A line connecting the third endpoint and the fourth endpoint and the second direction has a preset angle α4, α3≤α4.

17. The back contact cell according to claim 4, characterized in that The second convex region includes periodically repeated second convex units, the second convex units protrude toward the second doping region to form a second convex portion, and the second convex portion includes a third straight portion and a third arc portion.

18. The back contact cell according to claim 17, characterized in that A preset angle α3 is formed between the third straight portion and the second direction, two ends of the third arc portion are respectively a third endpoint and a fourth endpoint, the third arc portion is recessed toward the second doping region, a preset angle α4 is formed between a line connecting the third endpoint and the fourth endpoint and the second direction, α3≤α4.

19. The back contact cell according to claim 16 or 18, characterized in that The α3 is 15° to 40°, and the α4 is 25° to 50°.

20. The back contact cell according to claim 1, characterized in that Along the first direction, the width of the isolation region is 20 μm to 200 μm.

21. A back contact battery string, characterized in that: Comprising a back contact battery as claimed in any one of claims 1 to 20.

22. A solar cell module, characterized in that: Comprising a back-contact cell string as claimed in claim 21.

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