CN113644154B

CN113644154B - Photovoltaic module

Info

Publication number: CN113644154B
Application number: CN202111194930.1A
Authority: CN
Inventors: 刘俊辉; 陶武松
Original assignee: Jinko Solar Haining Co Ltd
Current assignee: Jinko Solar Haining Co Ltd
Priority date: 2021-10-14
Filing date: 2021-10-14
Publication date: 2022-01-25
Anticipated expiration: 2041-10-14
Also published as: CN113644154A

Abstract

The application provides a photovoltaic module, including a board, a board in a poor light, a reflection configuration and two at least battery pieces, board in a poor light sets up with the board in a poor light relatively. The battery piece sets up mutually at interval, and the battery piece sets up between the board of face light and the board of being shaded from the sun, is provided with on the battery piece and welds the area, welds the area and extends along first direction. The first reflection structure is arranged on one side, close to the backlight plate, of the surface light plate, corresponds to the space of the battery piece and/or is arranged in a welding strip, the first reflection structure is used for reflecting light rays from the space of the battery piece and/or the welding strip to the battery piece, the first reflection structure extends along a first direction, an arc surface is arranged at one end, close to the backlight plate, of the first reflection structure, and the radian of the arc surface ranges from 30 degrees to 180 degrees. In the above scheme, through setting up the first reflection configuration that has directional reflection ability, improved photovoltaic glass's secondary light reflectivity to promote the secondary light available quantity of battery piece, and then promote subassembly power and generating efficiency.

Description

Photovoltaic module

Technical Field

The invention relates to the technical field of photovoltaics, in particular to a photovoltaic module.

Background

In the photovoltaic module, the reflection effects of different areas such as a battery piece, a welding strip and a battery piece gap on sunlight are different (the reflectivity of a metal welding strip and a polymer back plate at the battery gap on the sunlight is far higher than that of the battery piece), and the sunlight flux reaching the front plate glass is reflected by the different areas and has obvious difference; the solar flux incident to the back plate through the cell gap, the back surface of the cell and other regions is also obviously different (the cell plate is basically opaque, and the light flux received by the back plate in the cell gap region is far higher than that in the back surface region of the cell plate).

According to the patterned glass of the photovoltaic module in the prior art, the inner surface of the patterned glass is mostly in a uniform pattern structure, and when sunlight reflected or incident in different areas in the photovoltaic module is subjected to secondary diffuse reflection, obvious direction characteristics and regional differences are avoided, and the improvement effect on the overall available luminous flux of a battery piece is limited.

Disclosure of Invention

In view of this, the present application provides a photovoltaic module, which is used to solve the problem in the prior art that the effect of patterned glass on reflecting sunlight is poor.

The photovoltaic module comprises a surface light plate, a backlight plate, a first reflection structure and at least two battery pieces, wherein the backlight plate and the surface light plate are arranged oppositely. The battery piece sets up mutually at interval, the battery piece set up in between the plane worn-out fur and the board that is shaded from the sun, be provided with on the battery piece and weld the area, it extends along first direction to weld the area. The first reflection structure is arranged on one surface, close to the backlight plate, of the surface light plate, the first reflection structure corresponds to the interval of the battery pieces and/or the welding strips, the first reflection structure extends along the first direction, an arc surface is arranged at one end, close to the backlight plate, of the first reflection structure, and the radian of the arc surface ranges from 30 degrees to 180 degrees.

In the scheme, the first reflection structure with the directional reflection capability is designed for the inner surface of the front plate glass at the corresponding position of the region (the welding strip, the interval of the cell pieces and the like) with stronger sunlight reflection capability in the photovoltaic module, so that the secondary light reflectivity of the photovoltaic glass is improved, the secondary light available quantity of the cell pieces is improved, and the power of the module and the power generation efficiency are further improved.

Additional features and advantages of embodiments of the present application will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of embodiments of the present application. The objectives and other advantages of the embodiments of the application will be realized and attained by the structure particularly pointed out in the written description and drawings.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive labor.

FIG. 1 is a schematic diagram of a photovoltaic module according to the prior art;

fig. 2 is a schematic structural diagram of a photovoltaic module provided in an embodiment of the present application;

fig. 3 is a schematic structural diagram of a first reflective structure provided in an embodiment of the present application;

fig. 4 is a schematic reflection diagram (one) of a second reflection structure provided in the embodiment of the present application;

fig. 5 is a schematic reflection diagram (ii) of a second reflection structure provided in the embodiment of the present application;

fig. 6 is a schematic reflection diagram (iii) of a second reflection structure provided in the embodiment of the present application;

fig. 7 is a schematic diagram of light path reflection of the first reflective structure with different arc values.

Reference numerals:

100-a photovoltaic module;

1-a plane board;

11-a first reflective structure;

111-arc surface;

112-a groove reflective structure;

2-a backlight plate;

21-a second reflective structure;

3-a battery piece;

31-solder strip.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and together with the description, serve to explain the principles of the application.

Detailed Description

For better understanding of the technical solutions of the present application, the following detailed descriptions of the embodiments of the present application are provided with reference to the accompanying drawings.

It should be understood that the embodiments described are only a few embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

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 application. As used in the examples of this 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.

It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.

It should be noted that the terms "upper", "lower", "left", "right", and the like used in the embodiments of the present application are described in terms of the angles shown in the drawings, and should not be construed as limiting the embodiments of the present application. In addition, in this context, it will also be understood that when an element is referred to as being "on" or "under" another element, it can be directly on "or" under "the other element or be indirectly on" or "under" the other element via an intermediate element.

Specific examples of the structure of the photovoltaic module provided in the embodiments of the present application will be described below.

The cell described herein, which is collectively referred to as a solar cell, is a device that directly or indirectly converts solar radiation energy into electrical energy through a photoelectric effect or a photochemical effect by absorbing sunlight.

Referring to fig. 1, a conventional crystalline silicon photovoltaic device 100 generally adopts a structure of "a front light panel 1/a packaging material/a cell sheet 3/a packaging material/a backlight panel 2", when in use, one side of the front light panel 1 of the photovoltaic device 100 faces light, one side of the backlight panel 2 faces back light, the light passes through the front light panel 1 and irradiates on the cell sheet 3, and the photovoltaic device 100 generates electricity normally. The material of the front light plate 1 is usually transparent glass, the material of the back light plate 2 is transparent glass or a polymer back plate, and the packaging material is usually a film. While the light-transmitting glass is mainly embossed glass (surface embossing) or float glass (surface embossing). The inner surfaces of the surface light plate 1 and the backlight plate 2 are designed with pattern structures, sunlight reflected by regions such as a cell piece 3/solder strip 31/cell piece 3 gap and the like in the photovoltaic module 100 or sunlight incident at the cell gap can be further reflected to the cell piece 3 in a diffused manner, so that secondary utilization of the sunlight is realized, and the power of the photovoltaic module 100 can be improved to a certain extent.

However, in the prior art, the pattern structures on the inner surfaces of the front light panel 1 and the back light panel 2 are uniformly distributed diffuse reflection structures, and when light rays are emitted in the direction facing the high reflection region (the interval between the cell pieces 3 and the solder strip 31) inside the photovoltaic module 100, the light rays cannot be well reflected to the cell pieces 3 for use, so that certain photovoltaic utilization efficiency is lost.

In view of the above, referring to fig. 2 and fig. 3, the present application provides a photovoltaic module 100, which includes a front light panel 1, a back light panel 2, a first reflective structure 11 and at least two battery pieces 3, in some embodiments, the plurality of battery pieces 3 are connected in series or in parallel, each two adjacent battery pieces 3 can be electrically connected through a conductive metal strip, and a certain space exists between each two adjacent battery pieces 3. The backlight plate 2 in the photovoltaic module 100 is disposed opposite to the front panel 1, and in some embodiments, the photovoltaic module 100 includes the front panel 1, the encapsulant, the battery pieces 3, the encapsulant, and the backlight plate 2, which are sequentially disposed from top to bottom.

The packaging material may be EVA (ethylene-vinyl acetate copolymer), which is a thermosetting hot melt adhesive, and has no viscosity at normal temperature, so that the packaging material can be easily handled, and can be melted, bonded, cross-linked and cured by hot pressing under certain conditions to become completely transparent. The packaging material can separate the fragile battery piece 3 from the surface light plate 1 and the backlight plate 2, can play a certain role in cushioning and buffering, and is favorable for enhancing the structural strength and the service life of the photovoltaic module 100.

The backlight plate 2 can be TPT (Tedlar Polymer Tellar), PET (Polyethylene terephthalate polyester) or transparent glass, the TPT is of a Tedlar/Polymer/Tedlar three-layer composite structure, the PET is of a single-layer polyester structure, and the backlight plate 2 is used on the back of the assembly and is used as a back protection and electrical insulation material and mainly used for resisting environmental erosion. The color of the backlight plate 2 can be white, so that the backlight plate 2 plays a certain role in reflecting sunlight energy and improves the power generation efficiency.

Each cell 3 is tiled between the surface light plate 1 and the backlight plate 2, a welding strip 31 is arranged on each cell 3, the welding strip 31 is also called a tinned copper strip or a tinned copper strip, also called an interconnector, and is mainly used for connection between the cells 3, plays an important role in conducting and gathering electricity, the surface reflection of the welding strip 31 is strong, and light can be reflected when irradiating on the welding strip 31. The solder strips 31 on the battery pieces 3 extend along the first direction and are arranged on one surface of the panel 1 close to the backlight plate 2.

The first reflection structures 11 on the panel 1 are disposed corresponding to the spaces of the battery pieces 3 and/or the solder strips 31, in other words, the first reflection structures 11 are disposed at the spaces of the battery pieces 3 and the projection positions of the solder strips 31 on the battery pieces 3 on the panel 1, and when light irradiates the first reflection structures 11 from the spaces of the battery pieces 3 or the directions of the solder strips 31, the first reflection structures 11 directionally reflect the light to the surfaces of the battery pieces 3.

Referring to fig. 2, in one embodiment, the first reflective structure 11 extends along a first direction, and an arc surface 111 is disposed at an end of the first reflective structure 11 close to the backlight panel 2.

Because the first reflecting structure 11 needs to reflect the light reflected by the solder strip 31 back to the surface of the battery piece 3, the first reflecting structure 11 extends along the first direction (the solder strip 31 also extends along the first direction), and one end of the first reflecting structure 11 close to the backlight plate 2 is provided with an arc surface 111, which is to further improve the reflecting effect of the light, so that the light irradiated to the first reflecting structure 11 is irradiated to the position of the battery piece 3 without the solder strip 31 (i.e. the surface of the battery piece 3 where power can be generated) under the reflection of the arc surface 111. In this embodiment, the first reflective structure 11 is substantially in the shape of a cylinder with a circumferential surface partially protruding from the plane light plate 1.

In one embodiment, the arc surface 111 has an arc of between 30 ° and 180 °.

Referring to fig. 2 and 3, specifically, the radian of the circular arc surface 111 may be 30 °, 35 °, 40 °, 45 °, 50 °, 55 °, 60 °, 65 °, 70 °, 75 °, 80 °, 90 °, 100 °, 110 °, 120 °, 130 °, 140 °, 150 °, 155 °, 160 °, 165 °, 170 °, 175 °, 180 °. Referring to fig. 7, the first reflective structures 11 with different arc values are sequentially disposed on the plane light plate 1 shown in fig. 7 from left to right, and arrows indicate the illumination and reflection of light.

It can be understood that, the larger the camber value of the circular arc surface 111, the larger the range of the first reflecting structure 11 protruding from the light panel 1. When the arc value of the arc surface 111 is greater than 180 °, the portion of the first reflective structure 11, which is in contact with the light panel 1, of the arc surface 111 forms an inward-concave dead angle, which may affect the reflection of light. When the arc value of the arc surface 111 is smaller than 30 °, the range of the arc surface 111 on the first reflection structure 11 protruding from the surface light plate 1 is too small, the reflection effect of light rays emitted from the direction of the solder strip 31 is not obvious, and when the arc value of the arc surface 111 is smaller, the first reflection structure 11 is flatter (the smaller the arc value is, the closer to the plane is), at this time, the first reflection structure 11 reflects the light rays back to the position of the solder strip 31, and the photovoltaic power generation efficiency is further affected. Therefore, the radian of the arc surface 111 is set to be between 30 ° and 180 °, so that the power generation efficiency of the photovoltaic module 100 can be increased.

In conclusion, the first reflection structure 11 with the directional reflection capability is designed on the inner surface of the surface light plate 1 corresponding to the regions (the solder strips 31, the intervals of the cell pieces 3 and the like) with stronger sunlight reflection capability in the photovoltaic module 100, so that the secondary light reflectivity of the photovoltaic glass is improved, the secondary light available quantity of the cell pieces 3 is increased, and the power generation efficiency of the photovoltaic module 100 are further improved.

In some embodiments, the photovoltaic module 100 further includes a frame, the frame may be made of an aluminum alloy material or a stainless steel material, and when the frame is made of an aluminum alloy material, the strength and the corrosion resistance of the frame are very good. The frame can play the effect of supporting and protecting whole panel. The photovoltaic module 100 can also be connected to an external photovoltaic support through a frame, and a plurality of photovoltaic modules 100 can be connected with each other to form a photovoltaic power station.

In some embodiments, the photovoltaic module 100 further includes a junction box, a special electrical connection box is needed to connect the positive electrode and the negative electrode of the solar cell module after being led out from the back surface, the junction box can also protect the power generation system of the whole cell panel, and the junction box is equivalent to a current transfer station, and when a short circuit occurs in a cell 3, the short-circuited cell string can be automatically disconnected by using the junction box.

In order to ensure the service life, the junction box can be made of engineering plastics by injection molding, and anti-aging and anti-ultraviolet radiation agents can be added, so that the assembly can be ensured not to have aging and cracking phenomena after being used outdoors for a long time. The binding post can be made of electrolytic copper coated with nickel layer, which can ensure the reliability of electric conduction and electric connection.

In one embodiment, the radius of the circular arc surface 111 is 10% to 30% of the thickness of the flat panel 1.

Specifically, the radius of the circular arc surface 111 may be 10%, 15%, 20%, 25%, 28%, 29%, 30%. The applicant finds that, through a large number of experiments, on the premise that other conditions are not changed, when the radius of the arc surface 111 is 10% -30% of the thickness of the surface light plate 1, the power generation efficiency of the photovoltaic module 100 is high. Therefore, the radius of the arc surface 111 is set to 10% to 30% of the thickness of the surface light plate 1, so that the power generation efficiency can be increased.

In one embodiment, the surface of the arc surface 111 is provided with a groove reflective structure 112.

Referring to fig. 3, in order to further improve the reflection efficiency of the first reflection structure 11, a concave groove reflection structure 112 is further disposed on the surface of the arc surface 111, the specific shape of the concave groove reflection structure 112 may be a strip-shaped groove or a spherical groove, the cross-sectional shape of the strip-shaped groove may be a semicircle, and by disposing the concave groove reflection structure 112, the reflection efficiency of the first reflection structure 11 is further improved, and further, the power generation efficiency of the photovoltaic module 100 is improved.

In one embodiment, the depth of the groove reflection structure 112 is 5% to 10% of the radius of the arc surface 111.

Referring to fig. 3, in particular, the depth of the groove reflection structure 112 may be 5%, 6%, 7%, 8%, 9%, 10% of the radius of the arc surface 111. The deeper the depth of the groove reflective structure 112 on the surface of the arc surface 111, the greater the difficulty of manufacturing the groove reflective structure, so that the depth of the groove reflective structure 112 can be limited to improve the reflective efficiency of the first reflective structure 11 on the premise of saving cost.

In one embodiment, the photovoltaic module 100 further includes a second reflective structure 21, the second reflective structure 21 is disposed on a surface of the backlight panel 2 close to the front light panel 1, the second reflective structure 21 extends along the interval of the cell pieces 3, and the second reflective structure 21 is configured to reflect light entering toward the interval direction of the cell pieces 3 to the cell pieces 3.

Referring to fig. 2, because there is a gap between the cell 3 and the cell 3 due to the process limitation in the prior art, when the light penetrates the front panel 1 and enters the photovoltaic module 100, a part of the light inevitably penetrates into the space between the cell 3 and the back panel 2 along the gap between the cell 3 and the cell 3, and the part of the light is not fully utilized, which affects the power generation efficiency of the photovoltaic module 100. In order to solve the above problem, the second reflective structure 21 is disposed on the backlight plate 2, and the second reflective structure 21 reflects the light that should be emitted into the gap between the cell 3 and the cell 3 back to the space between the front light plate 1 and the cell 3, so as to improve the utilization rate of the light and the power generation efficiency of the photovoltaic module 100.

The first reflective structure 11 and the second reflective structure 21 can be realized by a pattern design on the surface of the glass embossing roller or by laser engraving.

In one embodiment, the height of the second reflective structure 21 protruding from the backlight plate 2 is 30% to 60% of the thickness of the backlight plate 2.

Referring to fig. 2, specifically, the height of the second reflective structure 21 protruding from the backlight plate 2 may be 30%, 35%, 40%, 45%, 50%, 55%, 60% of the thickness of the backlight plate 2. The applicant finds through experiments that when the height of the second reflecting structure 21 protruding from the backlight plate 2 is greater than 60% of the thickness of the backlight plate 2, the difficulty of manufacturing the backlight plate 2 is greatly increased, and the damage rate of the second reflecting structure 21 is increased. When the height of the second reflective structure 21 protruding from the backlight plate 2 is less than 30% of the thickness of the backlight plate 2, the second reflective structure 21 cannot reflect or block light entering along the gap between the cell 3 and the cell 3.

In one embodiment, the cross-sectional shape of the second reflective structure 21 near the end of the light-facing plate 1 is triangular.

Referring to fig. 3, 4, 5 and 6, it can be understood that the end of the second reflective structure 21 close to the light-facing plate 1 is configured as a triangular structure, so that the two sides of the triangular structure close to the light-facing plate 1 can reflect the light in the direction inclined at a certain angle with the vertical direction, and a part of the light can be directly reflected to the panel of the battery piece 3. Thus, the utilization rate of light and the power generation efficiency of the photovoltaic module 100 are improved.

In one embodiment, the included angle of the triangle close to the light-facing plate 1 is 30-150 °.

Referring to fig. 3, 4, 5 and 6, specifically, the included angle of the triangle close to the plane light plate 1 may be 30 °, 40 °, 50 °, 60 °, 70 °, 80 °, 90 °, 100 °, 110 °, 120 °, 130 °, 140 ° and 150 °. It can be understood that, when the angle of the triangle close to the light panel 1 is greater than 150 °, the top end of the second reflection structure 21 is relatively flat, and the light incident from the direction of the light panel 1 passes through the light panel 1 again under the reflection of the second reflection structure 21 to be incident into the outside, so that the light utilization rate is reduced. When the included angle of the triangle close to the light panel 1 is less than 30 °, the top end of the second reflective structure 21 is fragile and easily damaged.

In one embodiment, the cross-sectional shape of the second reflective structure 21 is trapezoidal.

Similar to the aforementioned scheme with a triangular cross section, the cross section of the second reflective structure 21 is trapezoidal, and the plane of two waist portions of the trapezoid can be used to reflect light, so that a part of light can be directly reflected to the panel of the battery piece 3. Thus, the utilization rate of light and the power generation efficiency of the photovoltaic module 100 are improved. The angle of the top angle of the trapezoid close to the plane light plate 1 is 30-150 degrees, so that the utilization rate of light and the power generation efficiency of the photovoltaic module 100 can be further improved.

In one of the embodiments, the surface of the second reflective structure 21 is provided with a reflective layer. Specifically, a metal aluminum film may be deposited on the surface of the second reflective structure 21, or a thin layer of white pigment (such as TiO) with high reflectivity may be coated on the surface of the second reflective structure 21₂And the like, and is integrated with the glass through processes such as tempering, sintering, and the like), thereby realizing high reflectivity to light.

In one embodiment, the first reflective structure 11 includes a solder strip reflective structure disposed corresponding to the solder strip 31 and a gap reflective structure disposed corresponding to the space between the battery pieces 3, and the width of the gap reflective structure in the connection line direction of the battery pieces is greater than the width of the solder strip reflective structure in the connection line direction of the battery pieces.

Since the width of the solder strip 31 is generally smaller than the gap between the battery pieces 3, the width of the gap reflection structure in the direction of the connecting line of the battery pieces is correspondingly larger than the width of the solder strip reflection structure in the direction of the connecting line of the battery pieces.

Taking the example that the solder strip reflecting structure and the gap reflecting structure are both arc surface structures, the diameter of the arc surface of the solder strip reflecting structure is smaller than that of the arc surface of the gap reflecting structure.

Thus, a good reflection effect can be ensured, and the utilization rate of light and the power generation efficiency of the photovoltaic module 100 are improved.

In any of the above embodiments, the Cell sheet may be any one of a conventional single crystal Cell, a PERC (Passivated emitter and Rear Cell) single crystal Cell, or an HJT (hetero junction with intrinsic Thin-layer) Cell, and compared with the conventional Cell, the PERC Cell exhibits a good efficiency advantage, and the efficiency can be improved by 1-1.5% compared with the conventional Cell; the HJT battery has the advantages of less energy consumption, simple process flow, small temperature coefficient and the like, and is a better high-efficiency silicon-based solar battery scheme; the solar cell has the advantages that the solar cell has the characteristic of better converting light energy into electric energy regardless of the conventional single crystal, the PERC single crystal or the HJT cell, the light energy conversion efficiency of the cell can be well improved, and the light energy utilization rate of the cell is further improved. Namely, the conventional single crystal, PERC single crystal or HJT battery has the characteristic of better converting light energy into electric energy, the light energy conversion efficiency of the battery piece can be well improved, and the light energy utilization rate is improved.

Examples of battery plates are given below:

the TOPCon battery realizes the passivation of the rear surface by means of a tunneling effect, and the conventional TOPCon battery sequentially comprises a semiconductor substrate, a tunneling oxide layer, a doped conducting layer and a rear surface passivation layer from inside to outside. The BSG borosilicate glass is formed by the diffusion of N-type TOPCon (contact passivation battery) in boron, and the cleaning and removing difficulty of the borosilicate glass is more difficult than that of phosphorosilicate glass; generally, a mixed acid solution with oxidability is adopted for removal; and after the surface is cleaned and dried, polishing the back surface. At present, the polished state of the rear surface of a semiconductor substrate has certain influence on an ultrathin tunneling oxide layer with a nanoscale thickness, so that the contact resistivity between the tunneling oxide layer and the semiconductor substrate is easily improved, the fluctuation of a filling factor of a solar cell is easily caused, and the photoelectric conversion efficiency of the cell is influenced.

The solar cell includes:

a semiconductor substrate, a back surface of the semiconductor substrate having a first texture structure, the first texture structure comprising two or more first sub-structures at least partially stacked, wherein, for the two or more first sub-structures at least partially stacked, in a direction away from and perpendicular to the back surface, a distance between a top surface of an outermost first sub-structure and a top surface of a first sub-structure adjacent thereto is less than or equal to 2 μm, and a one-dimensional size of the top surface of the outermost first sub-structure is less than or equal to 45 μm; the front surface of the semiconductor substrate has a second texture structure, which may include a pyramid-shaped microstructure;

a first passivation layer on the front surface of the semiconductor substrate;

a tunneling oxide layer on the first texture structure of the back surface of the semiconductor substrate;

the doped conducting layer is positioned on the surface of the tunneling oxide layer and has a doping element with the same conductivity type as the semiconductor substrate;

and a second passivation layer on the surface of the doped conductive layer.

The front surface of the semiconductor substrate may refer to a light receiving surface, i.e., a surface (light receiving surface) receiving solar light irradiation, and the rear surface of the semiconductor substrate refers to a surface opposite to the front surface. In some embodiments, the solar cell formed is a single-sided cell, the front surface may be referred to as a light-receiving surface, and the back surface may be referred to as a backlight surface. In some embodiments, the solar cell formed is a bifacial cell, and both the front and back surfaces may be light-receiving surfaces.

As an optional technical solution of the present application, the semiconductor substrate is an N-type crystalline silicon substrate (or a silicon wafer), and a P-type doped layer may be formed on a front surface of the semiconductor substrate by using any one or more processes of high-temperature diffusion, slurry doping, or ion implantation, so as to form a PN junction in the semiconductor substrate. In some embodiments, the semiconductor substrate may be one of a single crystal silicon substrate, a polycrystalline silicon substrate, a microcrystalline silicon substrate, or a silicon carbide substrate.

In some embodiments, the P-type doped layer is a boron-doped diffusion layer. The boron-doped diffusion layer is a P-type doped layer (i.e., a P + layer) formed by diffusing boron atoms to a certain depth on the front surface through a diffusion process using a boron source. For example, the boron source may be liquid boron tribromide.

In some embodiments, the front surface of the semiconductor substrate has a second texture comprising a pyramidal microstructure. The pyramid-shaped microstructure can be a tetrahedron, an approximate tetrahedron, a pentahedron, an approximate pentahedron and the like. The pyramid-shaped microstructures may be formed by subjecting a semiconductor substrate to a texturing process. The texturing process can be chemical etching, laser etching, mechanical method, plasma etching and the like. The pyramid-shaped microstructure enables the metal slurry to be better filled in the microstructure when the metal slurry is subjected to screen printing to form an electrode, so that more excellent electrode contact is obtained, the series resistance of a battery can be effectively reduced, and the filling factor is improved.

In some embodiments, the pyramid-shaped microstructure comprises a top portion far from the front surface of the semiconductor substrate and a bottom portion near the front surface of the semiconductor substrate, and the distance (or height) between the top portion and the bottom portion of the pyramid-shaped microstructure is less than or equal to 5 μm in a direction far from the front surface and perpendicular to the front surface, preferably, the distance is in a range of 2 μm to 5 μm. Specifically, it may be 2 μm, 2.5 μm, 2.8 μm, 3 μm, 3.5 μm, 3.8 μm, 4 μm, 4.2 μm, 4.5 μm, 4.8 μm or 5 μm. When the distance range of the pyramid-shaped microstructure is controlled within 5 μm, for example, 2 μm to 5 μm, the pyramid-shaped microstructure has the characteristics of low reflection, low recombination and easy filling, so that the photoelectric conversion efficiency of the cell is improved.

It is understood that the number of pyramid-like microstructures formed on the front surface cannot be exhaustive due to the anisotropy of the crystal orientation of the front surface silicon crystal, and the distance between the highest point of the convex top and the lowest point of the concave top of the pyramid-like microstructures randomly selected in a specific region may be referred to herein as a distance between the highest point of the convex top and the lowest point of the concave bottom of the pyramid-like microstructures. For example, the distance of the pyramid-shaped microstructure can be determined by measuring the surface shape of the semiconductor substrate using an Atomic Force Microscope (AFM). For example, a scanning range of about 40 μm × 40 μm is selected for the front surface, the front surface of the semiconductor substrate is scanned in the selected scanning range by an atomic force microscope, the feature size of the pyramidal microstructure of the front surface is measured, and the height value h is calculated. Specifically, the highest point ha of the convex top of the pyramid-shaped microstructure is selected from the measured feature size (AFM image), and the lowest point of the bottom corresponding to the top is hb, thereby obtaining h = ha-hb. In other embodiments, the heights of the plurality of pyramid-shaped microstructures in the second texture structure are randomly collected, and an average value is calculated, and the average value is defined as the height of the pyramid-shaped microstructure. For example, 4 pyramid-shaped microstructures with heights h1, h2, h3 and h4 are randomly selected, so that the height value of the pyramid-shaped microstructures is (h 1+ h2+ h3+ h 4)/4. That is, the average distance of the plurality of pyramid-shaped microstructures can be regarded as the distance of the pyramid-shaped microstructures on the front surface, and is used for characterizing the texture features of the front surface.

As an alternative solution of the present application, the first passivation layer includes a stacked structure of at least one or more of a silicon oxide layer, a silicon nitride layer, an aluminum oxide layer, and a silicon oxynitride layer.

In some embodiments, the thickness of the first passivation layer is in a range of 10nm to 120nm, and specifically may be 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, or 120nm, and the like, and may also be other values within the above range, which is not limited herein.

Optionally, the first passivation layer is a stacked passivation structure of an aluminum oxide layer and a silicon nitride layer. The aluminum oxide layer is arranged on the front surface of the semiconductor substrate, and the silicon nitride layer is arranged on the surface of the aluminum oxide layer. In some embodiments, the thickness of the aluminum oxide layer is 2nm to 10nm, and the refractive index of the aluminum oxide layer is 1.5 to 1.8; the thickness of the silicon nitride layer is 50nm-110nm, and the refractive index of the silicon nitride layer is 1.65-2.25. The first passivation layer has an overall refractive index of 1.9-2.0. In some embodiments, the aluminum oxide layer or the silicon nitride layer may include a plurality of sub-layers, for example, the silicon nitride layer is composed of 2 to 5 silicon nitride sub-layers.

Optionally, the first passivation layer is a laminated passivation structure of an aluminum oxide layer, a silicon nitride layer and silicon oxynitride, which are sequentially stacked, wherein the aluminum oxide layer has a thickness range of 2nm to 10nm, the aluminum oxide layer has a refractive index range of 1.5 to 1.8, the silicon nitride layer has a thickness range of 40nm to 80nm, the silicon nitride layer has a refractive index range of 1.9 to 2.3, the silicon oxynitride layer has a thickness range of 10nm to 60nm, and the silicon oxynitride layer has a refractive index range of 1.5 to 1.75.

Further, the rear surface of the semiconductor substrate has a first texture structure. Specifically, the first texture structure may be formed through an alkali polishing process.

As an alternative solution, the first texture structure comprises two or more first substructures at least partially stacked. The first texture structure presents a non-pyramid microstructure morphology. For example, the first texture feature may exhibit an approximately "step" -like topography, and the first sub-feature may be considered as a step of "steps".

For the at least partially stacked two or more first sub-structures, in a direction away from and perpendicular to the rear surface (which may also be understood as in the stacking direction), the distance H between the top surface of the outermost first sub-structure and the top surface of the first sub-structure adjacent thereto is less than or equal to 2 μm, and specifically may be 2 μm, 1.8 μm, 1.5 μm, 1.2 μm, 1.1 μm, 1.0 μm, 0.8 μm, 0.5 μm, 0.3 μm, 0.2 μm, 0.1 μm, or the like. When the distance H exceeds 2 micrometers, the roughness of the first texture structure is too large, and the thickness of the tunneling oxide layer formed on the first texture structure is larger, the tunneling oxide layer with high density and high uniformity is not favorable to be formed, and the tunneling and passivation effects of the tunneling oxide layer are further influenced; the roughness of the first texture structure is too small, and the smaller the thickness of the tunneling oxide layer formed on the first texture structure is, the less the contact with the electrode paste is. Preferably, the distance H between the top surface of the outermost first substructure and the top surface of the first substructure adjacent thereto is within 0.3 μm to 1.2 μm in a direction away from and perpendicular to the rear surface.

When three first substructures are stacked, the distance H between the top surface of the first substructure of any one layer and the top surface of the first substructure of the adjacent layer is 2 μm or less.

It can be understood that the distance between the top surface of the outermost first sub-structure and the top surface of the adjacent first sub-structure is controlled to be less than or equal to 2 μm, so that the roughness of the first texture structure can be controlled within a required range, the uniformity of the tunnel oxide layer formed on the first texture structure can be improved, the performance of the formed tunnel oxide layer is better, partial phosphorus concentration caused by phosphorus diffusion is further inhibited from being higher, the contact resistivity is reduced, the open-circuit voltage of the solar cell is improved, and the filling factor and the photoelectric conversion efficiency are improved.

The one-dimensional size L of the top surface of the outermost first substructure a is less than or equal to 45 μm, namely L is more than 0 and less than or equal to 45 μm, and optionally, the one-dimensional size L is within 2 μm-45 μm. Here, the one-dimensional dimension L of the top surface may be, specifically, a length, a width, a diagonal length, a diameter of a circle, and the like of the surface, and is not limited herein. In some embodiments, the one-dimensional size may refer to an average of one-dimensional sizes of top surfaces of the plurality of outermost first sub-structures within a predetermined range of regions of the rear surface of the substrate. The average one-dimensional size of the top surface of the outermost first substructure may specifically be 2 μm, 5 μm, 8 μm, 12 μm, 15 μm, 18 μm, 20 μm, 25 μm, 28 μm, 30 μm, 35 μm, 40 μm, 42 μm, 40 μm or 45 μm, etc. Preferably, the top surface of the outermost first sub-structure has an average one-dimensional dimension within 10 μm to 15 μm.

In a specific embodiment, the first texture structure further comprises two or more second sub-structures arranged adjacently and non-stacked, and a one-dimensional dimension L of a top surface of the second sub-structure far away from the back surface is less than or equal to 45 μm, that is, 0 < L ≦ 45 μm. Optionally, the one-dimensional size L of the first substructure 122 is within 2 μm to 45 μm, and specifically may be 2 μm, 5 μm, 8 μm, 12 μm, 15 μm, 18 μm, 20 μm, 25 μm, 28 μm, 30 μm, 32 μm, 35 μm, or 45 μm.

The pyramidal microstructure is different from the front surface, the top surface of the first substructure and/or the second substructure of the rear surface is a polygonal plane, and the shape of the polygonal plane comprises at least one of rhombus, square, trapezoid, approximate rhombus, approximate square and approximate trapezoid. It will be appreciated that in actual manufacturing, the top surface topography of the first or second sub-structure presents irregular polygonal planes but overall features approximating a diamond, square or trapezoid shape.

In some examples, due to the preparation of the subsequent passivation film layer, such as the first passivation layer, the tunneling oxide layer, the doped conductive layer, etc., some damage may be caused to the second texture structure and the initial structure of the first texture structure, for example, in a mass-produced solar cell, the second texture structure may further include a small amount of non-pyramid-shaped microstructures, which are formed because the pyramid tips of the pyramid-shaped microstructures are damaged.

In some examples, in measuring the texture dimension characteristic of the second texture or the first texture characterizing the solar cell, such as a one-dimensional dimension of the top surface of the first substructure, a distance between surfaces of adjacent first substructures, the film layer surface calibration may be directly measured by a testing instrument (optical microscope, atomic force microscope, scanning electron microscope, transmission electron microscope, etc.). In one case, since the film thickness is in the nano-scale, it can be directly obtained using the film measurement data corresponding to the second texture or the first texture, which is the sum of the film thickness and the texture size. In another case, the film thickness data may be subtracted from the film measurement data. The above measurement means are only examples, and the present application is not limited thereto.

And the tunneling oxide layer is positioned on the first texture structure of the back surface of the semiconductor substrate and can be a laminated structure of one or more of a silicon oxide layer, an aluminum oxide layer, a silicon oxynitride layer, a molybdenum oxide layer and a hafnium oxide layer. In other embodiments, the tunneling oxide layer may also be a silicon nitride layer containing oxygen, a silicon carbide layer containing oxygen, or the like. The thickness of the tunneling oxide layer is 0.8 nm-2 nm. Specifically, the thickness of the tunneling oxide layer is 0.8nm, 0.9nm, 1.0nm, 1.2nm, 1.4nm, 1.6nm, 1.8nm, 2nm, or the like. The thickness of the tunneling oxide layer refers to the thickness of the tunneling oxide layer relative to the formation surface. The thickness of the tunneling oxide layer formed on the first texture structure can be obtained by observing and calculating a cross section with a normal direction of an inclined surface of the sub-structure as a thickness direction. The thickness of the tunneling oxide layer is too large, which is not favorable for reducing the contact resistance of the tunneling oxide layer. By controlling the thickness of the tunnel oxide layer, a decrease in the fill factor caused by contact resistance can be suppressed.

Specifically, the band gap width of the tunneling oxide layer is larger than 3.0eV, and the carriers are generally difficult to transmit through the tunneling oxide layer through thermal emission, but because the tunneling oxide layer is very thin, the carriers can pass through the tunneling oxide layer through a tunneling effect, so that the tunneling oxide layer with the thickness of 0.8 nm-2 nm has no barrier to the transmission of majority carriers. As the thickness of the tunnel oxide layer gradually increases, the tunneling effect of the majority carriers is affected, the carriers are difficult to transmit through the tunnel oxide layer, and the photoelectric conversion efficiency of the cell gradually decreases. When the thickness of the tunneling oxide layer is too small, the passivation effect cannot be achieved. Preferably, the tunneling oxide layer is a silicon oxide layer, and the thickness of the tunneling oxide layer is 0.8 nm-1.5 nm.

A tunneling oxide layer thickness D1 on a top surface of the outermost first sub-structure is less than a tunneling oxide layer thickness D2 formed on a side surface of the outermost first sub-structure. Specifically, a difference in thickness (D2-D1) between the tunnel oxide layer on the top surface of the outermost first substructure and the tunnel oxide layer formed on the side surface of the outermost substructure is 0.15nm or less. The thickness difference may be specifically 0.14nm, 0.13nm, 0.12nm, 0.11nm, 0.10nm, 0.09nm, 0.08nm, 0.07nm, 0.06nm, 0.05nm, 0.04nm, or the like. When the tunnel oxide layer on the top surface of the outermost first substructure and the tunnel oxide layer formed on the side surface of the outermost substructure are too large, the thickness uniformity of the tunnel oxide layer is poor, the current density of the solar cell is easily affected, and the open-circuit voltage of the solar cell is reduced.

In some embodiments, by providing different topographies of texture on the front and back surfaces of the semiconductor substrate, a pyramid-like texture structure is formed on the front surface and a non-pyramid texture structure is formed on the rear surface, the formed cell can have light trapping structures with different layers, the effective contact area of light is increased, and moreover, for the first texture structure formed on the back surface, the distance between the top surface of the outermost first sub-structure and the top surface of the first sub-structure adjacent to the top surface of the outermost first sub-structure is controlled within 2 μm, which is beneficial to reducing the hole density (pinhole) in the tunneling oxide layer and further improving the compactness and uniformity of the tunneling oxide layer, and furthermore, the local doping concentration of the doped conducting layer on the surface of the tunneling oxide layer is further inhibited from being higher, the contact resistivity is reduced, the open-circuit voltage of the solar cell is improved, and the filling factor and the photoelectric conversion efficiency are improved.

In some embodiments, the doped conductive layer may be a doped polysilicon layer, a doped microcrystalline silicon layer, a doped amorphous silicon layer, the doped conductive layer having a doping element of the same conductivity type as the semiconductor substrate.

When the semiconductor substrate is an N-type single crystal silicon substrate, the doped conductive layer is an N-type doped polysilicon layer, an N-type doped microcrystalline silicon layer, or an N-type doped amorphous silicon layer, and the doping element may be an N-type doping element such as phosphorus.

In some embodiments, the doped conductive layer has a thickness in the range of 60nm to 200nm, e.g., an N-type doped polysilicon layer, and the doped conductive layer has a refractive index in the range of 3.5 to 4.5.

As an optional technical solution of the present application, the second passivation layer includes at least one of a silicon nitride layer, a silicon oxide layer, and a silicon oxynitride layer. The thickness of the second passivation layer is 70nm-120 nm. For example, the second passivation layer is a silicon nitride layer having a low silicon-nitrogen ratio, the refractive index of the silicon nitride layer is in a range of 1.7 to 2.1, the refractive index of the silicon nitride layer may be 1.7, 1.8, 1.9, 2.0, 2.1, or the like, or may have other values within the above range, which is not limited herein. By controlling the refractive index of the silicon nitride layer to have a low silicon-nitrogen ratio, the formed second passivation layer can reduce the contact resistivity during metallization, thereby further reducing the contact resistivity of the solar cell.

In some embodiments, when the second passivation layer is a stacked silicon nitride layer and a silicon oxide layer or a stacked silicon nitride layer and a silicon oxynitride layer, the silicon nitride layer is located on the surface of the doped conductive layer, and the silicon oxide layer or the silicon oxynitride layer is located on the surface of the silicon nitride layer.

Furthermore, the solar cell further comprises a first electrode and a second electrode, the first electrode penetrates through the first passivation layer to form ohmic contact with the P-type doped layer (for example, the boron-doped diffusion layer) on the front surface of the semiconductor substrate, the second electrode penetrates through the second passivation layer to form ohmic contact with the doped conducting layer, and the doped conducting layer and the tunneling oxide layer form a passivation contact structure. The first electrode and the second electrode can be formed by sintering metal conductive paste coated on the surfaces of the first passivation layer and the second passivation layer. In some embodiments, the material of the first electrode or the second electrode includes a metal material such as silver, aluminum, copper, nickel, and the like.

For a solar cell, that is, a second texture structure of a pyramid-shaped microstructure is formed on the front surface of a semiconductor substrate, a first texture structure of a non-pyramid-shaped microstructure is formed on the rear surface of the semiconductor substrate, a matched first passivation layer (for example, a stacked passivation structure of an aluminum oxide layer and a silicon nitride layer) is formed on the second texture structure, and a matched tunneling oxide layer, a doped conductive layer and a second passivation layer (for example, a silicon nitride layer) are formed on the first texture structure, the solar cell structure has high photoelectric conversion efficiency.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A photovoltaic module, comprising:

a plane board;

the backlight plate is arranged opposite to the surface light plate;

the solar cell comprises at least two cell pieces, a backlight plate and a plurality of welding strips, wherein the cell pieces are arranged at intervals, the cell pieces are arranged between the backlight plate and the surface light plate, and the cell pieces are provided with the welding strips which extend along a first direction; and

the first reflecting structure is arranged on one surface of the surface light plate close to the backlight plate, and the first reflecting structure is arranged corresponding to the interval of the battery pieces and/or the welding strips;

the first reflection structure extends along the first direction, an arc surface is arranged at one end, close to the backlight plate, of the first reflection structure, and the radian of the arc surface is 30-180 degrees;

the surface of the arc surface is provided with a groove reflection structure.

2. The photovoltaic module of claim 1, wherein the radius of the circular arc surface is 10% to 30% of the thickness of the panel light plate.

3. The photovoltaic module of claim 1, wherein the groove reflecting structure depth is 5% to 10% of the radius of the circular arc surface.

4. The assembly according to claim 1, further comprising a second reflective structure disposed on a side of the backlight panel adjacent to the front panel, the second reflective structure extending along the space between the cells.

5. The photovoltaic module of claim 4, wherein the second reflective structure protrudes from the backlight panel by a height of 30% to 60% of the thickness of the backlight panel.

6. The assembly according to claim 4 or 5, wherein the second reflective structure is triangular in cross-section at an end thereof adjacent to the light-facing sheet.

7. The photovoltaic module of claim 6 wherein the included angle of the triangle proximate the light-facing sheet is from 30 ° to 150 °.

8. A photovoltaic module according to claim 4 or 5, wherein the cross-sectional shape of the second reflective structure is trapezoidal.

9. A photovoltaic module according to claim 4, characterized in that the surface of the second reflective structure is provided with a reflective layer.

10. The photovoltaic module of claim 9, wherein the reflective layer is a metallic aluminum film or a titanium oxide film.

11. The photovoltaic module according to claim 1, wherein the first reflective structure includes a solder strip reflective structure disposed corresponding to the solder strip and a gap reflective structure disposed corresponding to the space between the cells, and a width of the gap reflective structure in the cell connecting line direction is greater than a width of the solder strip reflective structure in the cell connecting line direction.