Back contact solar cell and photovoltaic module

Abstract

The application relates to a back contact solar cell and a photovoltaic module, which comprise a silicon substrate, a first passivation layer, a protective layer, a first electrode and a second electrode. The silicon substrate has opposite first and second surfaces. The second surface of the silicon substrate is provided with P-type and N-type conductive regions arranged at intervals. The first passivation layer is arranged on the first surface of the silicon substrate. The protective layer is arranged on the side of the first passivation layer away from the silicon substrate. The first electrode is electrically connected with the P-type conductive regions, and the second electrode is electrically connected with the N-type conductive regions. The protective layer can prevent other back contact solar cells or other objects from contacting the surface of the first passivation layer, so that the surface of the first passivation layer is prevented from being scratched or damaged by other objects, thereby ensuring the passivation effect of the first passivation layer on the first surface and improving the photoelectric conversion efficiency of the back contact solar cell. In addition, the arrangement of the protective layer can still have a good protective effect on the surface of the first passivation layer when a plurality of back contact solar cells are stacked unevenly, and it is not necessary to additionally arrange a separation component between adjacent two back contact solar cells in the sorting and collecting process, so that the sorting and collecting efficiency of the plurality of back contact solar cells can be improved, and the structure is simple, the preparation is convenient, and the preparation cost is saved.

Description

TECHNICAL FIELD

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

[0002] A solar cell is a kind of photovoltaic semiconductor wafer that directly generates electricity by using sunlight, also known as "solar chip" or "photovoltaic cell". It can output voltage and generate current in a loop as long as it is illuminated by light with a certain illumination condition.

[0003] A back contact solar cell, also known as IBC (Interdigitated back contact) cell, has no metal grid on the front surface, and the positive and negative metal electrodes are arranged in an interdigital manner on the back surface. Since there is no grid on the front surface, it has good photoelectric conversion efficiency. However, after the cell is printed with metal grid and sent to the module, the front surface film of the cell is easily damaged. Currently, a separator is usually added between two cells, but during sorting and collection, the cells are not collected uniformly or the separator is misaligned, which still increases the risk of scratching the front surface film of the cell. SUMMARY

[0004] Therefore, the present application provides a back contact solar cell and a photovoltaic module to solve the problem of damage to the front surface film of the cell during the process of printing the cell with metal grid and sending it to the module.

[0005] The first aspect of the present application provides a back contact solar cell, comprising a silicon substrate, a first passivation layer, a protective layer, a first electrode and a second electrode, the silicon substrate has opposite first and second surfaces, the second surface of the silicon substrate is provided with P-type and N-type conductive regions arranged at intervals, the first passivation layer is arranged on the first surface of the silicon substrate, the protective layer is arranged on the side of the first passivation layer away from the silicon substrate, the first electrode is electrically connected with the P-type conductive region, and the second electrode is electrically connected with the N-type conductive region.

[0006] In a possible design, along the thickness direction of the back contact solar cell, the projected area of the protective layer is 2% to 3% of the projected area of the silicon substrate.

[0007] In a possible design, the thickness of the protective layer is H1, and 5 μm≤H1≤60 μm.

[0008] In a possible design, the protective layer comprises a plurality of support pieces, and the plurality of support pieces are arranged at intervals on the side of the first passivation layer away from the silicon substrate.

[0009] In a possible design, the distance between the geometric centers of two adjacent support pieces is d, and 0<d≤20 mm.

[0010] In a possible design, the cross-sectional shape of the support in the direction perpendicular to the thickness direction of the back contact solar cell is one or a combination of a circle, a semicircle, a ring, a rectangle, a triangle, a diamond, a W shape, and a V shape.

[0011] In a possible design, the cross-sectional shape of the support in the direction perpendicular to the thickness direction of the back contact solar cell is a circle, and the radius of the circle is R1, where 0 < R1 ≤ 4 mm.

[0012] In a possible design, the cross-sectional shape of the support in the direction perpendicular to the thickness direction of the back contact solar cell is a strip-shaped structure formed by a combination of a semicircle and a rectangle, the radius of the semicircle is R2, where 0 < R2 ≤ 2 mm, and the length of the rectangle is L, where 1 ≤ L / R2 ≤ 5.

[0013] In a possible design, the protective layer is a transparent protective layer.

[0014] In a possible design, the material of the protective layer is one or a combination of acrylic, epoxy resin, polyurethane, and silicone.

[0015] The second aspect of the present application provides a photovoltaic module, which includes a cell string, an encapsulation layer, and a cover plate, the cell string is connected by a plurality of back contact solar cells as in any of the embodiments, the encapsulation layer is used to cover the surface of the protective layer of the cell string, and the cover plate is used to cover the surface of the encapsulation layer away from the cell string.

[0016] In the present application, the protective layer is arranged on one side of the first surface of the first passivation layer of the back silicon substrate, which can prevent other back contact solar cells or other objects stacked with each other from contacting the surface of the first passivation layer, so as to protect the first passivation layer after the first electrode and the second electrode are printed on the back contact solar cell, avoid the surface of the first passivation layer being scratched or damaged by other objects, and thus ensure the passivation effect of the first passivation layer on the first surface and improve the photoelectric conversion efficiency of the back contact solar cell.

[0017] In addition, since the protective layer is directly arranged on the side of the first passivation layer away from the silicon substrate, no relative displacement is generated relative to the surface of the first passivation layer, the protective effect of the first passivation layer surface is good even when the plurality of back contact solar cells are stacked unevenly, and no additional isolation component needs to be additionally arranged between the adjacent two back contact solar cells in the process of sorting and collecting, so as to improve the sorting and collecting efficiency of the plurality of back contact solar cells, and the structure is simple and convenient to prepare, thereby saving the preparation cost of the back contact solar cell.

[0018] It should be understood that the foregoing general description and the following detailed description are only exemplary and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0020] Figure 1 A sectional structure diagram of the back contact solar cell provided by the present application in a specific embodiment;

[0021] Figure 2 A sectional structure diagram of the back contact solar cell provided by the present application in another specific embodiment;

[0022] Figure 3 A partial structure schematic diagram of the back contact solar cell provided by the present application;

[0023] Figure 4 A top view of the back contact solar cell provided by the present application in a specific embodiment;

[0024] Figure 5 A sectional structure diagram of the back contact solar cell provided by the present application in a specific embodiment; Figure 4 A partial enlarged view of A in FIG. 6;

[0025] Figure 6 A top view of the back contact solar cell provided by the present application in another specific embodiment;

[0026] Figure 7 A sectional structure diagram of the back contact solar cell provided by the present application in a specific embodiment; Figure 6 A partial enlarged view of B in FIG. 7;

[0027] Figure 8 A structure schematic diagram of the photovoltaic module provided by the present application.

[0028] REFERENCE SIGNS:

[0029] 100 - back contact solar cell;

[0030] 1 - silicon substrate;

[0031] 11 - first surface;

[0032] 12 - second surface;

[0033] 121 - P-type conductive region;

[0034] 122 - N-type conductive region;

[0035] 2 - first electrode;

[0036] 3 - second electrode;

[0037] 4-protective layer;

[0038] 41-support;

[0039] 5-first passivation layer;

[0040] 6-first doped conductive layer;

[0041] 7-second doped conductive layer;

[0042] 8-second passivation layer;

[0043] 9-antireflection layer;

[0044] 10a-first tunneling dielectric layer;

[0045] 10b-second tunneling dielectric layer;

[0046] 110-cell string;

[0047] 120-encapsulation layer;

[0048] 130-cover plate;

[0049] X-first direction;

[0050] Y-second direction;

[0051] Z-thickness direction.

[0052] The drawings incorporated herein in the specification and form a part of the specification, show embodiments consistent with the present application, and together with the specification serve to explain the principles of the present application. DETAILED DESCRIPTION

[0053] In order to better understand the technical solutions of the present application, the embodiments of the present application will be described in detail below in conjunction with the drawings.

[0054] In the description of the present application, unless otherwise explicitly specified and limited, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance; unless otherwise specified or explained, the term "multiple" means two or more; the terms "connection", "fixation" and the like should be understood in a broad sense, for example, "connection" can be fixed connection, or detachable connection, or integrally connected, or electrically connected; it can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0055] The terminology used in the embodiments of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used in the description of the embodiments of the present application and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0056] It should be understood that the term "and / or" used in the present application only describes an association relationship of associated objects, and means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in the present application generally represents an "or" relationship between the front and rear associated objects.

[0057] It should be noted that the terms "upper", "lower", "left", "right", and the like described in the embodiments of the present application are described from the angle shown in the drawings, and should not be understood as limiting the embodiments of the present application. In addition, in the context, it should also be understood that when referring to an element connected to another element "on" or "under", it can be directly connected to another element "on" or "under" or indirectly connected to another element "on" or "under" through an intermediate element.

[0058] The back contact solar cell, referred to as IBC (Interdigitated back contact) cell, has no metal grid on the front surface, and the positive and negative metal electrodes are arranged in an interdigital manner on the back surface. Because there is no grid on the front surface, it has good photoelectric conversion efficiency, but after the cell is printed with a metal grid, the cell is stacked with multiple cells during the process of being sent to the assembly, which can easily damage the front surface film of the cell. At present, a separator is usually added between two cells, but during the sorting and collecting process, the cells are not collected uniformly or the separator is misaligned, which can still increase the risk of scratching the front surface film of the cell.

[0059] Based on this, the present application provides a back contact solar cell and a photovoltaic module. The back contact solar cell includes but is not limited to, for example, an interdigitated back contact (IBC) cell, a hybrid passivated back contact (HPBC) cell, a tunneling oxide passivated contact back contact (TBC) cell, a heterojunction back contact (HBC) cell, and the like, which are not limited herein.

[0060] The present application will be further described in detail below with specific embodiments and in conjunction with the drawings.

[0061] As shown in Figure 1 The back contact solar cell 100 has a length direction, a width direction and a thickness direction Z. For ease of understanding, the width direction of the back contact solar cell 100 is defined as the first direction X, and the length direction is defined as the second direction Y.

[0062] As shown in Figure 1 The back contact solar cell 100 includes a silicon substrate 1, a first passivation layer 5, a protective layer 4, a first electrode 2 and a second electrode 3. The silicon substrate 1 has opposite first and second surfaces 11 and 12. The first passivation layer 5 is disposed on the first surface 11 of the silicon substrate 1, and the protective layer 4 is disposed on the side of the first passivation layer 5 away from the silicon substrate 1. The second surface 12 of the silicon substrate 1 is provided with P-type and N-type conductive regions 121 and 122 arranged at intervals. The first electrode 2 is electrically connected to the P-type conductive region 121, and the second electrode 3 is electrically connected to the N-type conductive region 122.

[0063] The silicon substrate 1 is used to receive incident light and generate photo-generated carriers. The first surface 11 of the silicon substrate 1 can be referred to as the light-receiving surface, i.e., the surface on which the structure is illuminated by sunlight. The second surface 12 of the silicon substrate 1 is opposite the first surface 11. In some embodiments, the silicon substrate 1 is a silicon substrate, which can include one or more of single crystal silicon, polycrystalline silicon, amorphous silicon or microcrystalline silicon. In other embodiments, the material of the silicon substrate 1 can also be silicon carbide, organic material or multi-element compound. The multi-element compound can include, but is not limited to, perovskite, gallium arsenide, cadmium telluride, copper indium selenide and the like. Exemplarily, the silicon substrate 1 in the present application is a single crystal silicon substrate. The silicon substrate 1 has a doping element therein, and the doping element can be of N-type or P-type. The N-type element can be a group V element such as phosphorus (P) element, bismuth (Bi) element, antimony (Sb) element or arsenic (As) element, and the P-type element can be a group III element such as boron (B) element, aluminum (Al) element, gallium (Ga) element or indium (In) element. For example, when the silicon substrate 1 is a P-type silicon substrate, the doping element therein is of P-type. For another example, when the silicon substrate 1 is an N-type silicon substrate, the doping element therein is of N-type. Exemplarily, the silicon substrate 1 in the embodiments of the present application is of N-type to improve the photoelectric conversion efficiency of the back contact solar cell 100 and reduce the manufacturing cost.

[0064] The first and second electrodes 2 and 3 are used to collect and aggregate the current of the back contact solar cell 100. Exemplarily, the first and second electrodes 2 and 3 can be prepared by screen printing and sintering. In some embodiments, the metal paste used to prepare the first and second electrodes 2 and 3 can be one or more of aluminum, silver, gold, nickel, molybdenum or copper, without limitation.

[0065] The first passivation layer 5 can achieve good passivation on the first surface 11 of the silicon substrate 1, reduce the interface state density, reduce the recombination of minority carriers, improve the transmission efficiency of carriers at the interface, and improve the photoelectric conversion efficiency of the back contact solar cell 100. For example, the first passivation layer 5 can be deposited by plasma enhanced chemical vapor deposition, and of course other methods such as organic chemical vapor deposition can also be used to form the first passivation layer 5. The first passivation layer 5 can be a single layer structure or a stacked structure, and the thickness of each layer can be designed accordingly. Specifically, the first passivation layer 5 can be any one or a combination of silicon nitride layer, silicon oxynitride layer, silicon oxide layer, and aluminum oxide. Of course, the first passivation layer 5 can also use other types of passivation layers, which are not limited here.

[0066] In this embodiment, as shown in Figure 1 The protective layer 4 is arranged on one side of the first passivation layer 5 away from the first surface 11 of the silicon substrate 1, which can prevent other back contact solar cells 100 or other objects from contacting the surface of the first passivation layer 5, thereby protecting the first passivation layer 5 after the first electrode 2 and the second electrode 3 are printed on the back contact solar cell 100, or during the assembly into a photovoltaic module, preventing the surface of the first passivation layer 5 from being scratched or damaged by other objects, thereby ensuring the passivation effect of the first passivation layer 5 on the first surface 11 and improving the photoelectric conversion efficiency of the back contact solar cell 100.

[0067] In addition, since the protective layer 4 is directly arranged on the side of the first passivation layer 5 away from the silicon substrate 1, there is no relative displacement relative to the surface of the first passivation layer 5, which can still provide good protection for the surface of the first passivation layer 5 when the multiple back contact solar cells 100 are stacked unevenly, and there is no need to additionally add a separation component between the adjacent two back contact solar cells 100 during sorting and collecting, which can improve the sorting and collecting efficiency of the multiple back contact solar cells 100, and the structure is simple and easy to manufacture, saving the manufacturing cost of the back contact solar cell 100.

[0068] As shown in Figure 1 and Figure 2 The back contact solar cell 100 further comprises a first doped conductive layer 6, a second doped conductive layer 7, and a second passivation layer 8.

[0069] The first doped conductive layer 6 is arranged on the P-type conductive region 121 of the second surface 12 of the silicon substrate 1. The first doped conductive layer 2 can act as an emitter, and the first doped conductive layer 2 and the doped element in the substrate 1 are different in type, which can together form a PN junction structure. For example, when the substrate 1 is an N-type silicon substrate, the P-type first doped conductive layer 2 can be formed by boron diffusion on the silicon substrate 1 at the P-type conductive region 121.

[0070] The second doped conductive layer 7 is disposed on the N-type conductive region 122 of the second surface 12 of the silicon substrate 1. The doped element in the second doped conductive layer 7 is the same as that of the silicon substrate 1, and a concentration difference is formed between the second doped conductive layer 7 and the silicon substrate 1, so that the second doped conductive layer 7 can form good contact with the second electrode 3, and can form a band bending on the surface of the N-type conductive region 122 to realize selective transmission of carriers and reduce recombination loss. Any one of the physical vapor deposition method, the chemical vapor deposition method, the plasma enhanced chemical vapor deposition method, and the atomic layer deposition method can be used to deposit the second doped conductive layer 7 on the N-type conductive region 122.

[0071] The second passivation layer 8 is disposed on the side of the first doped conductive layer 6 and the second doped conductive layer 7 away from the silicon substrate 1 and at least part of the second surface 12. The second passivation layer 8 can achieve good passivation on the side of the first doped conductive layer 6 and the second doped conductive layer 7 away from the silicon substrate 1 and at least part of the second surface 12. Exemplarily, the second passivation layer 8 can be deposited by the plasma enhanced chemical vapor deposition method, and of course other methods such as organic chemical vapor deposition method can also be used to form the second passivation layer 8. The second passivation layer 8 can be a single-layer structure or a stacked structure, and the thickness of each layer can be designed accordingly. Specifically, the second passivation layer 8 can be any one or a combination of silicon nitride layer, silicon oxynitride layer, silicon oxide layer, and aluminum oxide layer. Of course, the second passivation layer 8 can also use other types of passivation layers, which are not limited herein.

[0072] The first electrode 2 is electrically connected to the first doped conductive layer 6 through the second passivation layer 8, and the second electrode 3 is electrically connected to the second doped conductive layer 7 through the second passivation layer 8.

[0073] It should be noted that, as shown in Figure 1 exemplarily, the P-type conductive region 121 and the N-type conductive region 122 can be formed on the surface of the second surface 12 of the silicon substrate 1; as shown in Figure 2 exemplarily, the P-type conductive region 121 and the N-type conductive region 122 can also be formed below the surface of the second surface 12, i.e. the P-type conductive region 121 and the N-type conductive region 122 are formed inside the silicon substrate 1. Of course, the P-type conductive region 121 and the N-type conductive region 122 can also be partially formed on the second surface 12, and can also be partially formed below the second surface 12, which can be set according to actual needs, and is not limited herein.

[0074] In addition, as shown in Figure 2 exemplarily, the back contact solar cell 100 can further include an anti-reflection layer 9 disposed between the first passivation layer 5 and the protective layer 4.

[0075] The anti-reflection layer 9 can reduce or eliminate the reflection of light on the surface of the back contact solar cell 100, increase the amount of light transmission, and further improve the photoelectric conversion efficiency of the back contact solar cell 100. The anti-reflection layer 9 can be a silicon nitride layer, thereby further reducing the difficulty of manufacturing the back contact solar cell 100 and improving the manufacturing efficiency. Of course, the anti-reflection layer 9 can also be a silicon oxynitride layer or a single layer or a stacked layer structure composed of silicon nitride and silicon oxynitride, or other anti-reflection film layer structures, which are not limited herein.

[0076] In a specific embodiment, as shown in Figure 2 The back contact solar cell 100 can further include a first tunneling dielectric layer 10a and a second tunneling dielectric layer 10b. The first tunneling dielectric layer 10a is disposed between the first doped conductive layer 6 and the silicon substrate 1, and the second tunneling dielectric layer 10b is disposed between the second doped conductive layer 7 and the silicon substrate 1.

[0077] As shown in Figure 2 The first tunneling dielectric layer 10a and the second tunneling dielectric layer 10b reduce the interface state density between the silicon substrate 1 and the first doped conductive layer 6 and the second doped conductive layer 7 through chemical passivation, reduce the recombination of minority carriers and holes, and improve the passivation effect of the surface of the silicon substrate 1. The first tunneling dielectric layer 10a and the second tunneling dielectric layer 10b can also allow majority carriers to tunnel into the first doped conductive layer 6 and the second doped conductive layer 7, and then make the majority carriers transport laterally in the first doped conductive layer 6 and the second doped conductive layer 7, thereby facilitating the collection of carriers by the first electrode 2 and the second electrode 3 and improving the open-circuit voltage and short-circuit current of the back contact solar cell 100. In addition, the first tunneling dielectric layer 10a and the second tunneling dielectric layer 10b can form a passivation contact structure with the first doped conductive layer 6 and the second doped conductive layer 7, respectively, which can achieve excellent interface passivation and selective collection of carriers, thereby improving the photoelectric conversion efficiency of the back contact solar cell 100.

[0078] The material of the first tunneling dielectric layer 10a and the second tunneling dielectric layer 10b can include, but is not limited to, one or more of a single layer or a stacked layer structure made of silicon oxide, silicon nitride, silicon oxynitride, molybdenum oxide, hafnium oxide, silicon carbide, magnesium fluoride, nanocrystalline silicon, intrinsic amorphous silicon, and intrinsic polycrystalline silicon, and other dielectric materials having a tunneling effect. In other embodiments, the first tunneling dielectric layer 10a and the second tunneling dielectric layer 10b can also be an oxygen-containing silicon nitride layer, an oxygen-containing silicon carbide layer, and the like, which are not limited herein. In some feasible embodiments, ozone oxidation method, high-temperature thermal oxidation method, nitric acid oxidation method, chemical vapor deposition method, low-pressure chemical vapor deposition method, and the like can be used to form the tunneling layer on the second surface 12 side of the silicon substrate 1.

[0079] In a specific embodiment, asFigure 3 As shown, the thickness of the protective layer 4 is H1, and 5 μm≤H1≤60 μm. For example, the thickness H1 of the protective layer 4 can be 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, etc. Of course, the thickness H1 of the protective layer 4 can also be other values within the above range, which can be designed according to actual needs, and is not limited herein.

[0080] In this embodiment, as shown in Figures 1-3 If the thickness H1 of the protective layer 4 is too large, for example, H1>60 μm, the overall thickness of the back contact solar cell 100 will increase, and the preparation cost of the back contact solar cell 100 will also increase. In addition, when assembled into a photovoltaic module, the thickness H1 of the protective layer 4 that is too large will also easily lead to a decrease in the adhesion of the back contact solar cell 100 to other components, and the difficulty of setting a film layer structure such as an encapsulation layer on the surface of the back contact solar cell 100 will increase, thereby increasing the assembly difficulty of the photovoltaic module. If the thickness H1 of the protective layer 4 is too small, for example, H1<5 μm, the protective isolation effect of the protective layer 4 is poor, and when multiple back contact solar cells 100 are stacked with each other, the surface of the first passivation layer 5 still has a risk of being scratched and damaged.

[0081] Therefore, when the thickness H1 of the protective layer 4 satisfies 5 μm≤H1≤60 μm, the thickness of the protective layer 4 is moderate, has a high protective isolation effect, can protect the surface of the first passivation layer 5 from being scratched and damaged, and has a low preparation cost, is convenient to prepare and form, and is conducive to the batch production of the back contact solar cell 100 and the assembly and formation of the photovoltaic module.

[0082] Further, as shown in Figure 1 and Figure 2 The maximum thickness H2 between the side surface of the second passivation layer 8 of the back contact solar cell 100 away from the silicon substrate 1 and the side surface of the first passivation layer 5 (or the anti-reflection layer 9) away from the silicon substrate 1, i.e., the sum of the maximum thicknesses of each film layer of the back contact solar cell 100 except the protective layer 4, the first electrode 2, and the second electrode 3, can be between 90 μm and 210 μm, so as to improve the design freedom of the back contact solar cell 100, which can be set according to actual needs, and is not limited herein.

[0083] In one specific embodiment, as shown in Figure 4As shown, the projected area of the protective layer 4 is 2% to 3% of the projected area of the silicon substrate 1 along the thickness direction Z of the back contact solar cell 100. For example, the projected area of the protective layer 4 is 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, or the like of the projected area of the silicon substrate 1. Of course, other values within the above range can also be used, and the specific value can be set according to actual needs, which is not limited herein.

[0084] As shown in FIG. 1, Figure 1 and 4 If the projected area of the protective layer 4 is too large, for example, greater than 3% of the projected area of the silicon substrate 1, the absorption of light by the silicon substrate 1 will be affected, the optical loss will be obvious, the current loss will be more, and the photoelectric conversion efficiency of the back contact solar cell 100 will be easily reduced. For example, when the projected area of the protective layer 4 is greater than 5% of the projected area of the silicon substrate 1, the current loss is greater than 50 mA, and the photoelectric conversion efficiency of the back contact solar cell 100 is reduced.

[0085] If the projected area of the protective layer 4 is too small, for example, less than 2% of the projected area of the silicon substrate 1, the area of the first passivation layer 5 exposed is large, and when the adjacent two back contact solar cells 100 are not stacked in place and are staggered with each other, the surface of the first passivation layer 5 still has the risk of being scratched and damaged, and the protective isolation effect of the protective layer 4 is poor.

[0086] In this embodiment, as shown in FIG. 1, Figure 4 When the projected area of the protective layer 4 is 2% to 3% of the projected area of the silicon substrate 1, the influence of the protective layer 4 on the light absorption of the silicon substrate 1 is small, the optical loss is small, and the current loss is low. In this embodiment, when the projected area of the protective layer 4 is 2% to 3% of the projected area of the silicon substrate 1, the current loss is less than 30 Ma. At the same time, the protective layer 4 has a good protective isolation effect, which can protect the first passivation layer 5 and other film layers on the first surface 11 of the silicon substrate 1 from being scratched and damaged, thereby ensuring that the back contact solar cell 100 has a high photoelectric conversion efficiency.

[0087] In a specific embodiment, the protective layer 4 is a transparent protective layer, which can allow light to pass through the protective layer 4 and enter the first surface 11, thereby further reducing the optical loss and improving the photoelectric conversion efficiency of the back contact solar cell 100.

[0088] In a specific embodiment, the material of the protective layer 4 is one or a combination of acrylic resin, epoxy resin, polyurethane, and silicone.

[0089] The acrylic resin, epoxy resin, polyurethane, silicone glue and other materials of the adhesive system have high transparency, good gloss and color retention, and low cost. The materials are not easy to damage the first passivation layer 5 and other film layers on the first surface 11 and the back contact solar cell 100 in contact with them, further reducing optical loss and saving cost.

[0090] In a specific embodiment, as shown in Figures 4-6 The protective layer 4 includes a plurality of supports 41, which are arranged at intervals on the side of the first passivation layer 5 away from the silicon substrate 1.

[0091] In this embodiment, as shown in Figure 4 and Figure 6 The support 41 can maintain a certain distance between the first passivation layer 5 arranged on the first surface 11 and other back contact solar cells 100 or other objects stacked with each other, so as to avoid scratches and damage to the surface of the first passivation layer 5 caused by contact with other objects. The plurality of supports 41 form a protective layer, which can be uniformly arranged on the side of the first passivation layer 5 away from the silicon substrate 1, thereby improving the uniform support force provided by the protective layer 4 to the objects stacked on its surface, thereby reducing the relative sliding and ensuring the stability of the plurality of back contact solar cells 100 during the stacking process. Further, the protective layer 4 is composed of a plurality of supports 41, which can further reduce the projected area of the protective layer 4 on the silicon substrate 1, thereby further reducing the optical loss of the back contact solar cell 100 while ensuring the high protective and isolation effect of the protective layer 4.

[0092] In a specific embodiment, as shown in Figure 5 and Figure 7 The distance between the geometric centers of the two adjacent supports 41 is d, and 0 < d ≤ 20 mm. For example, the distance d between the geometric centers of the two adjacent supports 41 can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 15 mm, 18 mm, 20 mm, etc. Of course, the distance d between the geometric centers of the two adjacent supports 41 can also be other values within the above range, which can be set according to actual needs, and is not limited herein.

[0093] As shown in Figures 4-7As shown, if the distance d between the geometric centers of two adjacent support members 41 is too large, for example, d>20mm, the distance between the two adjacent support members 41 is too far, so that the back contact solar cell 100 or other objects stacked above the protective layer 4 is easy to reach the interval between the two adjacent support members 41 and contact the film layer structure such as the first passivation layer 5 on the first surface 11, thereby scratching and damaging the film layer structure such as the first passivation layer 5 on the first surface 11.

[0094] In this embodiment, as shown in Figures 4-7 As shown, when the distance d between the geometric centers of two adjacent support members 41 satisfies 0

[0095] In a specific embodiment, in the thickness direction Z perpendicular to the back contact solar cell 100, the cross-sectional shape of the support member 41 is one or a combination of circular, semicircular, annular, rectangular, triangular, diamond, W-shaped, and V-shaped, which is simple in structure, facilitates the preparation of the protective layer 4, and can improve the design freedom of the back contact solar cell 100.

[0096] Of course, the cross-sectional shape of the support member 41 can also be pentagonal, hexagonal, or other irregular pattern shapes, which can be set according to actual needs, and is not limited herein.

[0097] In a specific embodiment, as shown in Figure 4 and Figure 5 As shown, in the thickness direction Z perpendicular to the back contact solar cell 100, i.e., in the plane of the first direction X and the second direction Y, the cross-sectional shape of the support member 41 is circular, which is simple in structure and facilitates preparation, thereby further reducing the difficulty of preparing the protective layer 4 and saving costs.

[0098] As shown in Figure 4 and Figure 5 The radius of the circle is R1, and 0

[0099] When the cross-sectional shape of the support member 41 is circular, the projected area S of the protective layer 4 can be expressed by the formula... The calculation yields the result. In the formula, S represents the projected area of ​​the protective layer 4, in mm². 2 R1 is the cross-sectional radius of the support 41, in mm; M is the projected area of ​​the silicon substrate 1 in the thickness direction Z, in mm. 2 d is the distance between the geometric centers of the two adjacent support members 41, in mm.

[0100] According to the formula It is known that the projected area S of the protective layer 4 is proportional to the cross-sectional radius R1 of the support member 41. Therefore, if R1 is too large, the projected area of ​​a single support member 41 will be large, which will make the projected area S of the protective layer 4 too large, which will easily increase the optical loss of the back contact solar cell 100 and reduce the photoelectric conversion efficiency of the back contact solar cell 100.

[0101] Therefore, when the cross-sectional shape of the support member 41 is circular and its radius R1 satisfies 0 < R1 ≤ 4 mm, the projected area of ​​a single support member 41 will not be too large, ensuring that the support member 41 has a certain supporting force, thereby enabling the protective layer 4 to have a good protective and isolation effect. At the same time, this structural design can prevent the projected area S of the protective layer 4 from becoming too large, thereby reducing the optical loss caused by the protective layer 4 and ensuring that the back contact solar cell 100 can have a high photoelectric conversion efficiency.

[0102] In another specific embodiment, such as Figure 6 and Figure 7 As shown, in the thickness direction Z perpendicular to the back-contact solar cell 100, i.e., in the plane of the first direction X and the second direction Y, the cross-sectional shape of the support member 41 is a strip structure formed by a combination of semi-circle and rectangle. This structure of the support member 41 has the advantages of simple structure and easy fabrication, and can improve the support effect of the support member 41.

[0103] Specifically, the support member 41 of the strip structure consists of a rectangle and two semicircles disposed at opposite ends of the rectangle. For example, as shown... Figure 7 As shown, two semicircles are positioned on opposite sides of a rectangle along the second direction Y, and the width of the rectangle along the first direction X is the same as the diameter of the semicircles.

[0104] like Figure 6 and Figure 7As shown, the radius of the semicircle in the cross section of the support 41 is R2, and 0 < R2≤ 2 mm. For example, R2may be 0.5 mm, 0.75 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.6 mm, 1.8 mm, 2 mm, etc. Of course, the radius R2of the semicircle can also be other values within the above range, which can be set according to actual needs, and is not limited herein.

[0105] The length of the rectangle in the cross section of the support 41 is L, and 1≤ L / R2≤ 5. For example, L / R2may be 1, 2, 3, 4, 5, etc. Of course, L / R2may also be other values within the above range, and is not limited herein.

[0106] When the cross-sectional shape of the support 41 is a semicircle, the projected area S of the protective layer 4 can be calculated by the formula , where S is the projected area of the protective layer 4, in mm2; R2is the radius of the semicircle in the cross section of the support 41, in mm; L is the length of the rectangle in the cross section of the support 41, in mm; and M is the projected area of the silicon substrate 1 in the thickness direction Z, in mm2. 2 2 d is the distance between the geometric centers of the two adjacent supports 41, in mm.

[0107] According to the formula , it can be known that the projected area S of the protective layer 4 is proportional to the radius R2of the semicircle and the length L of the rectangle in the cross section of the support 41. Therefore, if R2and L are too large, the projected area of a single support 41 is large, so that the projected area S of the protective layer 4 is easily too large, which easily increases the optical loss of the back contact solar cell 100, thereby reducing the photoelectric conversion efficiency of the back contact solar cell 100.

[0108] Therefore, when the cross-sectional shape of the support 41 is a strip structure formed by a combination of a semicircle and a rectangle, and the radius R2of the semicircle in the cross section satisfies 0 < R2≤ 2 mm and the length L of the rectangle satisfies 1≤ L / R2≤ 5, the projected area of a single support 41 will not be too large, and the support 41 can have better supporting force, so that the protective layer 4 can have better protective isolation effect. At the same time, the structure setting can avoid the projected area S of the protective layer 4 being too large, thereby reducing the optical loss caused by the protective layer 4, so as to ensure that the back contact solar cell 100 can have higher photoelectric conversion efficiency.

[0109] The second aspect of the present application provides a photovoltaic module, such as Figure 8 ​As shown, the photovoltaic module includes a cell string 110, an encapsulation layer 120 and a cover plate 130. The cell string 110 is connected by a plurality of back contact solar cells 100 in any of the above embodiments, the encapsulation layer 120 is used to cover the surface of the cell string 110 protective layer 4, the cover plate 130 is used to cover the surface of the encapsulation layer 120 away from the cell string 110. Since the back contact solar cell 100 has the above technical effects, the photovoltaic module including the solar cell 100 should also have the above technical effects, which will not be repeated here.

[0110] As shown, the back contact solar cell 100 is electrically connected in the form of a whole piece or multiple pieces to form a plurality of cell strings 110, and the plurality of cell strings 110 are electrically connected in series and / or parallel. Specifically, the plurality of cell strings 110 can be electrically connected by a conductive band. Figure 8

[0111] The encapsulation layer 120 covers the front surface and the back surface of the back contact solar cell. Specifically, the encapsulation layer 120 can be an ethylene-vinyl acetate copolymer (EVA) film, a polyethylene octene elastomer (POE) film, a polyethylene terephthalate (PET) film, or a polyvinyl butyral (PVB) organic encapsulation film.

[0112] The cover plate 130 can be a glass cover plate, a plastic cover plate, or a cover plate 130 with a light transmission function. Specifically, the surface of the cover plate 130 facing the encapsulation layer 120 can be a concave-convex surface, thereby increasing the utilization rate of incident light.

[0113] In the present specification, the same or similar parts between various embodiments can be referred to each other. In particular, for the device embodiments and the terminal embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the description in the method embodiments.

[0114] The above only describes specific implementation ways of the present application, but the protection scope of the present application is not limited to this. Any changes or replacements within the technical scope disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.​

Claims

1. A back-contact solar cell, characterized in that, include: A silicon substrate (1) has a first surface (11) and a second surface (12) opposite to each other. P-type conductive regions (121) and N-type conductive regions (122) are arranged at intervals on one side of the second surface (12) of the silicon substrate (1). A first passivation layer (5) is disposed on the first surface (11) of the silicon substrate (1). A protective layer (4) is disposed on the side of the first passivation layer (5) away from the silicon substrate (1); The first electrode (2) is electrically connected to the P-type conductive region (121); The second electrode (3) is electrically connected to the N-type conductive region (122); The protective layer (4) includes a plurality of support members (41), which are spaced apart on the side of the first passivation layer (5) away from the silicon substrate (1); the distance between the geometric centers of two adjacent support members (41) is d, 0 < d ≤ 20 mm; In the thickness direction (Z) perpendicular to the back contact solar cell (100), the cross-sectional shape of the support (41) is circular, and the radius of the circle is R1, 0 < R1 ≤ 4 mm.

2. The back-contact solar cell according to claim 1, characterized in that, Along the thickness direction (Z) of the back-contact solar cell (100), the projected area of ​​the protective layer (4) is 2% to 3% of the projected area of ​​the silicon substrate (1).

3. The back-contact solar cell according to claim 1, characterized in that, The thickness of the protective layer (4) is H1, 5μm≤H1≤60μm.

4. The back-contact solar cell according to claim 1, characterized in that, In the thickness direction (Z) perpendicular to the back contact solar cell (100), the cross-sectional shape of the support member (41) is one or more combinations of a circle, a semi-circle, annular, rectangular, triangular, rhomboid, W-shaped, and V-shaped.

5. The back-contact solar cell according to any one of claims 1 to 4, characterized in that, The protective layer (4) is a transparent protective layer.

6. The back-contact solar cell according to any one of claims 1 to 4, characterized in that, The protective layer (4) is made of one or more of the following materials: acrylic resin, epoxy resin, polyurethane, and silicone.

7. A photovoltaic module, characterized in that, The photovoltaic module includes: A battery string (110) is formed by connecting a plurality of back-contact solar cells (100) as described in any one of claims 1 to 6; Encapsulation layer (120) is used to cover the surface of the protective layer (4) of the battery string (110); A cover plate (130) is used to cover the surface of the encapsulation layer (120) away from the battery string (110).

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