阅读说明：本技术 晶体硅太阳电池及晶体硅太阳电池的组合电池 (Crystalline silicon solar cell and combined cell of crystalline silicon solar cell ) 是由 吉河训太 于 2020-04-10 设计创作，主要内容包括：本发明涉及晶体硅太阳电池(100),包含搭迭连接有PERC型的太阳电池单元(1)而成的太阳电池串(10),太阳电池单元(1)具有：单晶硅衬底(2)、扩散层(3)、与扩散层(3)接触的第一采集电极(4)、与扩散层(3)及第一采集电极(4)接触的第一连接电极(5)、贯穿有开口部(70)的绝缘层(7)、与绝缘层(7)接触且经由开口部(70)与单晶硅衬底(2)连接的第二采集电极(8)、以及与第二采集电极(8)接触的第二连接电极(9),第一连接电极(5)与第二连接电极(9)分离,在相邻的两个太阳电池单元(1)的重叠区域(11)的大半部分或整个区域,第二采集电极(8)与单晶硅衬底(2)隔着绝缘层(7)分离。(The present invention relates to a crystalline silicon solar cell (100) including a solar cell string (10) in which PERC-type solar cell units (1) are connected in a stacked manner, wherein the solar cell units (1) have: the solar cell comprises a monocrystalline silicon substrate (2), a diffusion layer (3), a first collecting electrode (4) in contact with the diffusion layer (3), a first connecting electrode (5) in contact with the diffusion layer (3) and the first collecting electrode (4), an insulating layer (7) penetrating through an opening (70), a second collecting electrode (8) in contact with the insulating layer (7) and connected with the monocrystalline silicon substrate (2) through the opening (70), and a second connecting electrode (9) in contact with the second collecting electrode (8), wherein the first connecting electrode (5) is separated from the second connecting electrode (9), and the second collecting electrode (8) is separated from the monocrystalline silicon substrate (2) through the insulating layer (7) in most of or the whole of an overlapping region (11) of two adjacent solar cell units (1).)

1. A crystalline silicon solar cell comprises a solar cell string having a plurality of PERC-type solar cells respectively, and formed by overlapping and connecting two adjacent solar cells in the plurality of solar cells, wherein,

each of the plurality of solar battery cells has:

a single crystal silicon substrate of a unidirectional conductivity type having a first main surface and a second main surface;

a diffusion layer of a reverse conductivity type in contact with the first main surface;

a first collecting electrode in contact with the diffusion layer on a side opposite to a side in contact with the single crystal silicon substrate;

a first connection electrode in contact with the diffusion layer and the first collecting electrode;

an insulating layer in contact with the second main surface and having at least one opening penetrating therethrough;

a second collecting electrode which is in contact with the insulating layer on a side opposite to a side in contact with the single crystal silicon substrate and is connected to the single crystal silicon substrate via the at least one opening portion; and

a second connection electrode contacting the second collecting electrode on a side opposite to a side contacting the insulating layer,

in each of the plurality of solar battery cells, the first connection electrode is separated from the second connection electrode when viewed from a direction substantially perpendicular to the first main surface,

the solar cell string has an overlapping region where the adjacent two solar cell units overlap,

in the overlapping region, the first connection electrode of one solar cell unit of the two adjacent solar cell units is connected to the second connection electrode of the other solar cell unit of the two adjacent solar cell units in an overlapping state when viewed from a direction substantially perpendicular to the first main surface,

in each of the plurality of solar cell units,

the second collecting electrode is separated from the single crystal silicon substrate with the insulating layer interposed therebetween in most of the portion of the overlap region after the removal of a part of the overlap region or the entire region of the overlap region.

2. The crystalline silicon solar cell according to claim 1,

the second collecting electrode of each of the plurality of solar battery cells is arranged at least between an edge of the single crystal silicon substrate located on one side, which is a side where the second connection electrode is arranged in the arrangement direction of the plurality of solar battery cells in the solar battery string, and the second connection electrode.

3. The crystalline silicon solar cell according to claim 1 or 2,

the second connection electrode is separated from the single crystal silicon substrate with the insulating layer interposed therebetween.

4. The crystalline silicon solar cell according to any one of claims 1 to 3,

the first main surface is a light receiving surface.

5. The crystalline silicon solar cell according to any one of claims 1 to 4,

in each of the plurality of solar cell units,

an edge of the single crystal silicon substrate located on one side of the solar cell string on which the second connection electrode is arranged in the array direction of the plurality of solar cells includes: a surface substantially perpendicular to the first main surface, and a slope formed by laser irradiation when each of the plurality of solar battery cells is formed,

the distance between the edge of the second collecting electrode on the one side and the surface of the single-crystal silicon substrate substantially perpendicular to the first main surface is 150% or more of the width of the inclined surface in the arrangement direction.

6. The crystalline silicon solar cell according to any one of claims 1 to 5,

in each of the plurality of solar cell units,

the second collecting electrode has a distance between an edge of the second collecting electrode on the other side where the first connecting electrode is arranged in the arrangement direction of the plurality of solar battery cells in the solar battery string and an edge of the single crystal silicon substrate on the other side, which is 40% or more and 90% or less of the dimension of the overlapping region in the arrangement direction.

7. The crystalline silicon solar cell according to any one of claims 1 to 5,

in each of the plurality of solar cell units,

the second collecting electrode has a distance of 0.4mm or more between an edge of the second collecting electrode on the other side where the first connecting electrode is arranged in the arrangement direction of the plurality of solar battery cells in the solar battery string and an edge of the single crystal silicon substrate on the other side.

8. The crystalline silicon solar cell according to any one of claims 1 to 7,

the second connection electrodes are arranged at intervals in a direction substantially orthogonal to both the arrangement direction of the plurality of solar battery cells in the solar battery string and the thickness direction of the single crystal silicon substrate,

an opening of the insulating layer is disposed in a region of the second connection electrode spaced apart from the gap.

9. An assembled cell of a crystalline silicon solar cell is an assembled cell of a crystalline silicon solar cell in which a plurality of small sections are collected, and the small sections are divided into a plurality of solar cells of PERC type, respectively,

the assembled battery has one side and an opposite side of the one side,

each of the plurality of small partitions is divided by a dividing line which is a straight line substantially parallel to the one side of the assembled battery,

each of the plurality of small partitions has:

a single crystal silicon substrate of a unidirectional conductivity type having a first main surface and a second main surface;

a diffusion layer of a reverse conductivity type in contact with the first main surface;

a first collecting electrode in contact with the diffusion layer on a side opposite to a side in contact with the single crystal silicon substrate;

a first connection electrode in contact with the diffusion layer and the first collecting electrode;

an insulating layer in contact with the second main surface and having at least one opening penetrating therethrough;

a second collecting electrode which is in contact with the insulating layer on a side opposite to a side in contact with the single crystal silicon substrate and is connected to the single crystal silicon substrate via the at least one opening portion; and

a second connection electrode contacting the second collecting electrode on a side opposite to a side contacting the insulating layer,

in each of the plurality of small segments, the first connection electrode is separated from the second connection electrode when viewed from a direction substantially perpendicular to the first main face,

the second collecting electrode is separated from the one side of the assembled battery and from an opposite side of the one side of the assembled battery when viewed from a direction substantially perpendicular to the second main surface,

in a small cell including the one side of the assembled battery among the plurality of small cells, the second connection electrode is provided along the dividing line away from the one side of the assembled battery,

in a cell including the opposite side of the assembled battery among the plurality of cells, the second connection electrode is provided along the dividing line away from the opposite side of the assembled battery.

Technical Field

The present invention relates to a crystalline silicon solar cell including a solar cell string and an assembled cell of the crystalline silicon solar cell, wherein the solar cell string is connected with a plurality of solar cell units by lap connection.

Background

Conventionally, crystalline silicon solar cells having various structures have been proposed. As such a crystalline silicon solar cell, there is a solar module including a solar cell string (patent document 1). In this solar module, a plurality of rectangular solar battery cells are connected to each other at their ends in a state where long sides of two adjacent solar battery cells are arranged to overlap each other, for example, as in a roofing shingle, to form a solar battery string. In this solar module, the solar battery cells are arranged to overlap each other, so that a gap is not formed between the adjacent two solar battery cells. This can improve the charging rate of the solar battery cells in the solar module, thereby improving the module efficiency.

As a solar Cell constituting a crystalline silicon solar Cell, there is a PERC (Passivated Emitter and reader Cell) type solar Cell (patent document 2). The solar cell includes: a p-type silicon substrate; an n-type impurity diffusion region and a light-receiving surface electrode which are laminated at a time on the light-receiving surface side of the silicon substrate; and a back surface passivation film and a back surface electrode which are laminated on the back surface side of the silicon substrate at a time. The rear surface passivation film is a film provided with a plurality of openings. In such a solar cell, the dangling bonds of silicon atoms in the rear surface layer portion of the silicon substrate can be terminated by the rear surface passivation film. Therefore, in this solar cell, recombination can be suppressed. The connection position when the solar battery cells are connected to each other is not particularly limited.

Patent document 1: japanese Kohyo publication No. 2017-517145

Patent document 2: japanese laid-open patent application No. 2004-6565

Therefore, in a solar module in which solar cells are arranged in a stacked manner as described above, that is, in a lap-joint (shingling connection), a structure to which the PERC type solar cell is applied has not been sufficiently studied. Therefore, the most suitable structure is not proposed.

Disclosure of Invention

The invention aims to provide a crystalline silicon solar cell and a combined cell of the crystalline silicon solar cell, wherein the crystalline silicon solar cell is formed by overlapping and connecting PERC type solar cells and the structure of the crystalline silicon solar cell is optimized.

The crystalline silicon solar cell of the present invention includes a solar cell string having a plurality of solar cells each of which is of a PERC type, and each of the plurality of solar cells is formed by overlapping and connecting two adjacent solar cells, each of the plurality of solar cells having: a single crystal silicon substrate of a unidirectional conductivity type having a first main surface and a second main surface; a diffusion layer of a reverse conductivity type in contact with the first main surface; a first collecting electrode in contact with the diffusion layer on a side opposite to a side in contact with the single crystal silicon substrate; a first connection electrode in contact with the diffusion layer and the first collecting electrode; an insulating layer in contact with the second main surface and having at least one opening penetrating therethrough; a second collecting electrode which is in contact with the insulating layer on a side opposite to a side in contact with the single crystal silicon substrate and is connected to the single crystal silicon substrate via the at least one opening portion; and a second connection electrode that is in contact with the second collecting electrode on a side opposite to a side in contact with the insulating layer, the first connection electrode and the second connection electrode being separated from each other when viewed from a direction substantially perpendicular to the first main surface in each of the plurality of solar battery cells, the solar battery string having an overlap region where the adjacent two solar battery cells overlap, the first connection electrode of one solar battery cell of the adjacent two solar battery cells being connected to the second connection electrode of the other solar battery cell of the adjacent two solar battery cells in a state of overlapping when viewed from a direction substantially perpendicular to the first main surface in the overlap region, the first connection electrode being connected to the second connection electrode of the other solar battery cell of the adjacent two solar battery cells in each of the plurality of solar battery cells in a large half portion of the overlap region or the entire region of the overlap region excluding a part of the overlap region, the second collecting electrode is separated from the single crystal silicon substrate via the insulating layer.

In the crystalline silicon solar cell, the second collecting electrode of each of the plurality of solar battery cells may be disposed at least between an edge of the single crystal silicon substrate located on one side of the solar battery string on which the second connection electrode is disposed in the array direction of the plurality of solar battery cells and the second connection electrode.

In the crystalline silicon solar cell, the second connection electrode and the single crystal silicon substrate may be separated from each other with the insulating layer interposed therebetween.

In the crystalline silicon solar cell, the first principal surface may be a light-receiving surface.

In the crystalline silicon solar cell, each of the plurality of solar battery cells may be configured such that an edge of the single crystal silicon substrate on one side, which is a side where the second connection electrode is arranged in the array direction of the plurality of solar battery cells in the solar battery string, includes: and an inclined surface formed by laser irradiation when each of the plurality of solar battery cells is formed, wherein a distance between an end edge of the second collecting electrode on the one side and a surface of the single crystal silicon substrate substantially perpendicular to the first main surface is 150% or more of a width of the inclined surface in the arrangement direction.

In the crystalline silicon solar cell, in each of the plurality of solar battery cells, a distance between an edge of the second collecting electrode on the other side, which is a side where the first connecting electrode is arranged, in the arrangement direction of the plurality of solar battery cells in the solar battery string and an edge of the single crystal silicon substrate on the other side may be 40% or more and 90% or less of a dimension of the overlapping region in the arrangement direction.

In the crystalline silicon solar cell, the distance between the edge of the second collecting electrode on the other side, which is the side where the first connecting electrode is arranged, in the array direction of the plurality of solar battery cells in the solar battery string and the edge of the single crystal silicon substrate on the other side in the array direction of the plurality of solar battery cells in the plurality of solar battery cells may be 0.4mm or more.

In the crystalline silicon solar cell, the second connection electrode may be disposed at a distance from each other in a direction substantially orthogonal to both the arrangement direction of the plurality of solar battery cells in the solar battery string and the thickness direction of the single crystal silicon substrate, and the opening of the insulating layer may be disposed in a region of the second connection electrode spaced from the distance.

An assembled cell of a crystalline silicon solar cell according to the present invention is an assembled cell of a crystalline silicon solar cell in which a plurality of small segments are assembled, each of the plurality of small segments being divided into a plurality of solar cells of a PERC type, the assembled cell having one side and an opposite side to the one side, each of the plurality of small segments being divided by a dividing line which is a straight line substantially parallel to the one side of the assembled cell, each of the plurality of small segments having: a single crystal silicon substrate of a unidirectional conductivity type having a first main surface and a second main surface; a diffusion layer of a reverse conductivity type in contact with the first main surface; a first collecting electrode in contact with the diffusion layer on a side opposite to a side in contact with the single crystal silicon substrate; a first connection electrode in contact with the diffusion layer and the first collecting electrode; an insulating layer in contact with the second main surface and having at least one opening penetrating therethrough; a second collecting electrode which is in contact with the insulating layer on a side opposite to a side in contact with the single crystal silicon substrate and is connected to the single crystal silicon substrate via the at least one opening portion; and a second connection electrode contacting the second collecting electrode on a side opposite to a side contacting the insulating layer, in each of the plurality of small segments, the first connection electrode is separated from the second connection electrode when viewed from a direction substantially perpendicular to the first main face, the second collecting electrode is separated from the one side of the assembled battery and from an opposite side of the one side of the assembled battery when viewed from a direction substantially perpendicular to the second main surface, in a small cell including the one side of the assembled battery among the plurality of small cells, the second connection electrode is provided along the dividing line away from the one side of the assembled battery, in a cell including the opposite side of the assembled battery among the plurality of cells, the second connection electrode is provided along the dividing line away from the opposite side of the assembled battery.

Drawings

Fig. 1 is a side view of a crystalline silicon solar cell of the present embodiment.

Fig. 2 is a plan view of a solar cell unit constituting the crystalline silicon solar cell.

Fig. 3 is a bottom view of the solar battery cell.

Fig. 4 is a cross-sectional view at the position IV-IV of fig. 2.

Fig. 5 is a cross-sectional view at the V-V position of fig. 2.

Fig. 6 is an enlarged view of the vicinity of the second connection electrode of the solar cell unit of fig. 5.

Fig. 7 is a sectional view at the VI-VI position of fig. 3.

Fig. 8 is a plan view of an assembled battery, which is a semi-finished product of the solar battery cell.

Fig. 9 is a bottom view of the assembled battery.

Fig. 10A is a schematic diagram for explaining a process of forming a solar cell string from the assembled cell, and is a schematic diagram showing the assembled cell before being divided.

Fig. 10B is a schematic diagram for explaining a process of forming a solar cell string from the assembled battery, and is a schematic diagram showing the solar cell string.

Detailed Description

The present invention will be described below with reference to one embodiment and the accompanying drawings. In the following description, the term "solar cell" refers to the name of each plate-like portion constituting the "solar cell string". The drawings schematically show the structure of the present embodiment, and are different from the design drawings. Therefore, the dimensional relationship in the drawings may not necessarily be accurate.

As shown in fig. 1, the crystalline silicon solar cell 100 of the present embodiment includes a plurality of solar cells 1, and includes a solar cell string 10 in which two adjacent solar cells 1, 1 of the solar cells 1 are stacked and connected to each other. The solar cell string 10 is formed by overlapping one end portion of one solar cell 1 in the arrangement direction of the solar cells 1 … 1 with the other end portion of the other solar cell 1 in the arrangement direction of the solar cells 1 … 1, among the two adjacent solar cells 1, 1.

Each of the plurality of solar battery cells 1 … 1 is of a PERC type, and as shown in fig. 2 and 3, is rectangular (substantially rectangular) when viewed from a direction substantially perpendicular to the main surface. The dimension of the solar battery cell 1 in the short side direction is, for example, about 25 mm. As shown in fig. 4 and 5, the solar battery cell 1 includes: a single-crystal silicon substrate 2 of one-way conductivity type having a first main surface 21 and a second main surface 22; a diffusion layer 3 of reverse conductivity type provided on the first main surface 21 side; a first collecting electrode 4 (see fig. 5); and a first connecting electrode 5. As also shown in fig. 7, the solar cell 1 further includes a first insulating layer 6 provided on the first main surface 21 side. The solar cell 1 further includes a second insulating layer (insulating layer) 7 provided on the second main surface 22 side, a second collecting electrode 8, and a second connecting electrode 9. The solar battery cell 1 is, for example, a single-sided light-receiving type solar battery cell.

In the solar cell 1, the first connection electrode 5 and the second connection electrode 9 provided on the single-crystal silicon substrate 2 are separated from each other when viewed from a direction substantially perpendicular to the first main surface 21 of the single-crystal silicon substrate 2 (see fig. 1). The solar cell string 10 has an overlapping region 11 in which two adjacent solar cells 1 and 1 overlap each other. When viewed in a direction substantially perpendicular to the first main surface 21, the first connection electrode 5 of one solar cell 1 of the two adjacent solar cells 1, 1 and the second connection electrode 9 of the other solar cell 1 of the two adjacent solar cells 1, 1 are connected (lap-connected) in a state of overlapping in the overlapping region 11. The overlap region 11 includes: the first overlapping region 111 on one side where the second connection electrode 9 is arranged in the arrangement direction of the solar battery cells 1, and the second overlapping region 112 on the other side where the first connection electrode 5 is arranged in the arrangement direction of the solar battery cells 1 (see fig. 4 and 5).

The conductivity type (unidirectional conductivity type) of the single-crystal silicon substrate 2 may be n-type or p-type, for example, to dope the B concentration to 1e15/cm³Left and right p-type. In the case where the solar battery cell 1 is of a single-sided light-receiving type, the first main surface 21 of the single crystal silicon substrate 2 is a separate light-receiving surface. At least one base portion 23 is provided on the second main surface 22 side of the single crystal silicon substrate 2. The base portion 23 is formed at a portion in contact with the second collecting electrode 8, has the same conductivity type as the substrate, and is formed by diffusing B to 1e18/cm, for example, so that a large number of carriers can be efficiently recovered by using a dopant having a higher concentration than the substrate³P of about concentration⁺⁺And (4) a section. The base portion 23 has a shape along the shape of an opening of the second insulating layer 7 described later, and is, for example, a linear shape extending in a direction substantially orthogonal to both the arrangement direction of the solar cells 1 and the thickness direction of the single crystal silicon substrate 2.

One end edge 24 of the single-crystal silicon substrate 2 of the present embodiment (an end edge located on one side where the second connection electrode 9 is arranged in the arrangement direction of the solar battery cells 1) has: a vertical surface (cleavage surface) 240 which is a surface substantially perpendicular to the first main surface 21; and a slope 241 (see fig. 6) which is a laser mark formed by laser irradiation when the solar battery cell 1 described later is formed. In fig. 4 and 5, the shape of one end edge 24 of the silicon single crystal substrate 2 and the other end edge 25 of the silicon single crystal substrate 2 (the end edge on the other side where the first connection electrodes 5 are arranged in the arrangement direction) are shown as perpendicular planes, but actually have the shape shown in fig. 6.

The first collecting electrodes 4 are finger electrodes extending from the first connecting electrodes 5 in the arrangement direction of the solar battery cells 1 (see fig. 2). The first collecting electrode 4 is in contact with the diffusion layer 3 on the side opposite to the side in contact with the single crystal silicon substrate 2 (see fig. 5). Specifically, the first collecting electrode 4 is in contact with the surface 31 of the diffusion layer 3.

The first connecting electrode 5 is a bus bar electrode. The first connection electrode 5 is connected to the second connection electrode 9 of the solar battery cell 1 to be connected in a state where two adjacent solar battery cells 1, 1 are stacked and connected (see fig. 1). The first connecting electrode 5 is in contact with the diffusion layer 3 (specifically, the surface 31 of the diffusion layer 3) and the first collecting electrode 4 (see fig. 4 and 5).

Examples of the material of the first collecting electrode 4 and the first connecting electrode 5 include a paste-like material containing fine particles of a metal such as silver and a binder resin. Examples of the method of forming the first collecting electrode 4 and the first collecting electrode 4 include a printing method such as screen printing and a curing method such as baking.

The diffusion layer 3 may be of n-type or P-type as long as it has a conductivity type (reverse conductivity type) opposite to the first conductivity type, and is diffused with P to 1e18/cm, for example³N of right and left concentration⁺⁺And (4) a section. The diffusion layer 3 is in contact with the first main surface 21 of the single-crystal silicon substrate 2. As a material of the diffusion layer 3, for example, silicon nitride (SiN) is contained_X). The diffusion layer 3 is formed by, for example, printing and firing a first collecting electrode 4 and a first connecting electrode 5 containing a metal such as silver on a silicon nitride layer.

The first insulating layer 6 is laminated on the surface 31 of the diffusion layer 3 at a portion where the first collecting electrode 4 and the first connecting electrode 5 are not provided. As a material of the first insulating layer 6, for example, silicon nitride (SiN) is contained_X). The first insulating layer 6 is in contact with the diffusion layer 3 on the side opposite to the side in contact with the single-crystal silicon substrate 2 (see fig. 4). In addition, the first and second substrates are,the first insulating layer 6 is in contact with the diffusion layer 3 (for example, the surface 31 of the diffusion layer 3), the first collecting electrode 4, and the first connecting electrode 5 (see fig. 4 and 5).

The second insulating layer 7 is in contact with the second main surface 22 of the single-crystal silicon substrate 2 (see fig. 5). As a material of the second insulating layer 7, for example, silicon nitride (SiN) is contained_X). At least one opening 70 is formed through the second insulating layer 7. That is, the second insulating layer 7 has at least one opening 70 penetrating therethrough. The second insulating layer 7 is provided with a plurality of openings 70.

The opening 70 is formed by, for example, laser irradiation of the second insulating layer 7. In the second insulating layer 7 of the present embodiment, the opening 70 is provided in a region sandwiched at least between the first connection electrode 5 and the second connection electrode 9 when viewed from a direction substantially perpendicular to the first main surface 21 of the single-crystal silicon substrate 2. The opening 70 provided in this region is, for example, linear extending in a direction substantially orthogonal to both the arrangement direction of the solar cells 1 and the thickness direction of the single crystal silicon substrate 2 (see fig. 3). The dimension of the opening 70 in the short side direction is, for example, about 1mm to 3 mm. In the second insulating layer 7 of the present embodiment, the opening 70 is also provided in a region of the second connection electrode 9, which will be described later, where the space 90 is provided.

The second collecting electrode 8 is in contact with the second insulating layer 7 on the side opposite to the side in contact with the single crystal silicon substrate 2 (see fig. 4 and 5). The second collecting electrode 8 is connected to the single crystal silicon substrate 2 via the opening 70 of the second insulating layer 7. Second collecting electrode 8 of the present embodiment is formed in a plate shape along second main surface 22 of single crystal silicon substrate 2. The second collecting electrode 8 is in contact with the single crystal silicon substrate 2, thereby forming a base portion 23 in the single crystal silicon substrate 2.

The second collecting electrode 8 is separated from the single crystal silicon substrate 2 via the second insulating layer 7 in most of the second overlap region 112 (the overlap region 11 on the left side in fig. 4 and 5). The majority of the second overlapping area 112 referred to herein is the majority excluding a part of the second overlapping area 112. Further, the second collecting electrode 8 may be separated from the single crystal silicon substrate 2 via the second insulating layer 7 in the entire region of the second overlap region 112. In the solar battery cell 1 of the present embodiment, the second collecting electrode 8 is separated from the single-crystal silicon substrate 2 in a portion other than the end portion on the inner side in the arrangement direction of the second overlapped region 112, and the second collecting electrode 8 is in contact with the single-crystal silicon substrate 2 in the end portion on the inner side in the arrangement direction of the second overlapped region 112. The second collecting electrode 8 is arranged at a position of the second overlapping region 112, particularly in a region on the inner side in the arrangement direction of the second overlapping region 112, and is in contact with the single crystal silicon substrate 2 in order to collect carriers generated when sunlight is irradiated between the overlapping solar battery cells 1.

In a part of the first overlap region 111 (the overlap region 11 located on the right side of fig. 4 and 5) in the present embodiment, the second collecting electrode 8 is also in contact with the single crystal silicon substrate 2. The second collecting electrode 8 is in contact with the single crystal silicon substrate 2 to collect carriers generated at an end portion located on one side in the arrangement direction of the single crystal silicon substrate 2.

The second collecting electrode 8 of the present embodiment is disposed at least between one end edge 24 (an end edge located on one side in the arrangement direction of the solar battery cells 1) of the single crystal silicon substrate 2 and the second connection electrode 9. As shown in fig. 6, a distance L1 between one end edge 81 of the second collecting electrode 8, which is located on one side in the arrangement direction of the solar battery cells 1, and a vertical surface 240 of one end edge 24 of the single-crystal silicon substrate 2 is 150% or more of a width W of the inclined surface 241 of the one end edge 24 of the single-crystal silicon substrate 2 in the arrangement direction.

Further, a distance L2 between the other end edge 82 of the second collecting electrode 8 on the other side in the arrangement direction where the first connecting electrode 5 is arranged and the other end edge 25 of the single-crystal silicon substrate 2 is 40% or more and 90% or less of a dimension L3 of the second overlap region 112 in the arrangement direction. Further, a distance L2 between the other end edge 82 of the second collecting electrode 8 and the other end edge 25 of the single crystal silicon substrate 2 is, for example, 0.4mm or more. The dimension L3 of the second overlapping area 112 in the arrangement direction is about 1.5mm to 2.0 mm.

As a second collecting powerThe material of the electrode 8 includes, for example, a paste-like material containing fine particles made of a metal such as aluminum and a binder resin, and holes are doped in a part of the single crystal silicon substrate 2 by contact with the single crystal silicon substrate 2, so that a region in which holes are excessive (for example, p is formed)⁺⁺Base portion 23 of the section). As a forming method of the second collecting electrode 8, for example, a printing method including screen printing or the like and a curing method based on firing or the like are included. When second collecting electrode 8 contains aluminum, the position of opening 70 can be grasped from the appearance of second collecting electrode 8 because aluminum reacts with single-crystal silicon substrate 2 to generate AlSi (aluminum silicon) and discolors at the portion overlapping with opening 70 of second insulating layer 7.

The second connecting electrode 9 is in contact with the second collecting electrode 8 on the side opposite to the side in contact with the second insulating layer 7. The second connection electrode 9 is separated from the single crystal silicon substrate 2 through the second insulating layer 7. The second connection electrodes 9 are arranged at intervals 90 in a direction substantially orthogonal to both the arrangement direction of the solar cells 1 and the thickness direction of the single-crystal silicon substrate 2 (see fig. 3 and 7). The width of the space 90 in the direction perpendicular to the extending direction of the second connection electrode 9 is, for example, about 5 mm.

The material of the second connection electrode 9 includes, for example, a paste-like material containing fine particles made of a metal such as silver and a binder resin, which does not form a region having excess holes (for example, p) even if it is in contact with the single crystal silicon substrate 2⁺⁺Base portion 23 of the section). As a method of forming the second connection electrode 9, for example, a printing method including screen printing or the like and a curing method based on firing or the like are included.

In the solar cell 1, carriers generated on the single-crystal silicon substrate 2 move to the second connection electrode 9 via the base portion 23 and the second collecting electrode 8 in both the arrangement direction of the solar cell 1 and the direction substantially orthogonal to both the arrangement direction and the thickness direction of the single-crystal silicon substrate 2 (see fig. 4 to 7).

Such a solar cell unit 1 can be obtained by dividing the assembled battery 12, which is a semi-finished product in which the portions (small sections 120) of the solar cell unit 1 are collected, at the dividing lines 124 by laser light or the like. The assembled battery 12 has one side 121 and an opposite side 122 opposed to the one side 121. As shown in fig. 8 and 9, the assembled battery 12 is divided into a plurality of small segments 120 by a dividing line 124 that is a straight line (a straight line extending in the vertical direction in fig. 8 and 9) substantially parallel to one side 121 of the assembled battery 12. The assembled battery 12 has a square plate shape, for example, but may have a rectangular plate shape, an octagonal shape (an octagonal shape with corners of a square shape cut away), or the like. The number of the small cells 120 included in the assembled battery 12 is, for example, 5, but may be other numbers such as 6 as long as there are a plurality of the small cells.

The small segments 120 each have a structure corresponding to the solar battery cell 1. In the assembled battery 12, the second collecting electrode 8 is separated from one side 121 and from the opposite side 122 facing the one side 121 when viewed from the direction substantially perpendicular to the second main surface 22.

In a small partition 120 including one side 121 among the plurality of small partitions 120, the second connection electrode 9 is disposed along a dividing line 124 away from the one side 121. In addition, in the small cell 120 including the opposite side 122 among the plurality of small cells 120, the second connection electrode 9 is provided along the dividing line 124 distant from the opposite side 122. Specifically, in the small partition 120 including the one side 121, the second connection electrode 9 is disposed along the dividing line 124 in the vicinity of the dividing line 124 away from the one side 121, and in the small partition 120 including the opposite side 122, the second connection electrode 9 is disposed along the dividing line 124 in the vicinity of the dividing line 124 away from the opposite side 122.

In addition, the end portion 26 including the one side 121 and the opposite side 122 of the assembled battery 12 is likely to have a shorter life than other regions. In the assembled battery 12, the thicknesses of the respective layers may vary. For example, the thickness of the first insulating layer 6 located above the single-crystal silicon substrate 2 is likely to be thinner at the end 26 of the assembled battery 12 than at other portions of the first insulating layer 6.

The solar cell string 10 is obtained by stacking and connecting the solar cells 1 obtained from the assembled cells 12. For example, the solar cell units 1 obtained by dividing the assembled cells 12 at the dashed-dotted line in fig. 10A are connected to each other in a stacked manner so as to hide the end portions 26 as shown in fig. 10B, thereby obtaining the solar cell string 10. In the overlap connection, the first connection electrode 5 and the second connection electrode 9 of each of the two adjacent solar battery cells 1 and 1 are connected to each other by the metal paste 13 (see fig. 1). The metal paste 13 is, for example, silver paste, and is applied to the first and second connection electrodes 5 and 9 by a dispenser.

In the crystalline silicon solar cell 100 described above, the second collecting electrode 8 for collecting carriers is not disposed in most of the first overlapping region 111 and most of the second overlapping region 112, but it is difficult to generate power in the light-shielded first overlapping region 111. Therefore, even if the second collecting electrode 8 is not provided in the first overlap region 111 and the second overlap region 112, the consumption of the material of the second collecting electrode 8 can be suppressed. Thereby, the crystal silicon solar cell 100 having an optimized structure can be provided.

In the crystalline silicon solar cell 100 of the present embodiment, carriers generated in the single crystal silicon substrate 2 can be collected by the second collecting electrode 8 without increasing the path through which the carriers move from the single crystal silicon substrate 2 (movement according to the law of conservation of charge). Therefore, it is possible to suppress dark current and improve output, while reducing resistance and improving output.

In the crystalline silicon solar cell 100 of the present embodiment, the second insulating layer 7 is provided between the second connection electrode 9 and the single crystal silicon substrate 2, and thus the second connection electrode 9 and the single crystal silicon substrate 2 are not in contact with each other. Therefore, recombination of minority carriers generated by these contacts can be suppressed, and lifetime degradation can be suppressed. In particular, in the crystalline silicon solar cell 100 of the present embodiment, since the second connection electrode 9 is silver, P is not formed as in the base portion 23⁺⁺Accordingly, it is useful that the second connection electrode 9 is not in contact with the single crystal silicon substrate 2.

Further, since the crystalline silicon solar cell 100 of the present embodiment includes the solar cell 1 in which the first main surface 21 of the single crystal silicon substrate 2 is the light-receiving surface, the crystalline silicon solar cell 100 can be applied to a general PERC type solar cell.

In the crystalline silicon solar cell 100 of the present embodiment, when the assembled cell 12 is cut and irradiated with laser light in the manufacturing process of the solar cell 1, the second collecting electrode 8 is positioned away from the laser light irradiation site on one side in the arrangement direction, and therefore the second collecting electrode 8 is less likely to be damaged.

In the crystalline silicon solar cell 100 of the present embodiment, when the solar cell units 1 are connected in a stacked manner in the process of manufacturing the solar cell string, for example, the metal paste 13 is applied between the first connection electrode 5 and the second connection electrode 9 connected to the two adjacent solar cell units 1 and 1. In this case, even if the metal paste 13 is pushed and spilled by the first connecting electrode 5 and the second connecting electrode 9 and the spilled metal paste 13 spills from the portion of one solar cell 1 coated with the metal paste 13 to the back surface side, the other end edge 82 in the array direction of the solar cells 1 of the second collecting electrode is retreated inward (one side in the array direction) from the other end edge 25 of the single crystal silicon substrate 2, and therefore, the leakage due to the connection of the first connecting electrode 5 and the second collecting electrode 8 by the metal paste 13 hardly occurs.

In addition, in the crystalline silicon solar cell 100 of the present embodiment, since the second connection electrodes 9 are separated, a current can flow from the opening 70 to the adjacent second connection electrodes 9, and therefore, the resistance generated by the second connection electrodes 9 can be reduced, and the output can be further improved.

In the crystalline silicon solar cell 100 of the present embodiment, although the lifetime of minority carriers is short in the end portion 26 of the assembled cell 12, when the small segments 120 of the assembled cell 12 are separated and the small segments 120 are connected in a stacked manner as the solar cells 1, the stacked connection can be performed such that the portions of the assembled cell 12 that are the one side 121 and the opposite side 122 are positioned in the stacked region 11 where the solar cells 1 are stacked. In this case, in the overlap region 11, the single-crystal silicon substrate 2 is shielded from light and thus power generation is difficult, and therefore, the influence on the output can be suppressed. In the solar cell string 10, since the end 26 of the silicon wafer is hidden when viewed from the direction substantially perpendicular to the first main surface 21, even if the thickness of the first insulating layer 6 laminated on the end 26 of the assembled cell 12 is smaller than the thickness of the other part of the first insulating layer 6, for example, a crystalline silicon solar cell 100 having a good appearance can be obtained.

In addition, in the crystalline silicon solar cell 100 of the present embodiment, the second collecting electrode 8 is in contact with the single-crystal silicon substrate 2 in a part of the second overlapping region 112, for example, in an end portion of the second overlapping region 112 on the inner side in the arrangement direction. Therefore, the second collecting electrode 8 can collect carriers generated in a region close to the second overlap region 112 (a region in the single crystal silicon substrate 2 near the second overlap region 112), and thus can improve the output.

The crystalline silicon solar cell of the present invention is not limited to the above-described embodiments, and various modifications may be added thereto without departing from the scope of the present invention. For example, the structure of another embodiment may be added to the structure of an embodiment, or a part of the structure of an embodiment may be replaced with the structure of another embodiment. Further, a part of the structure of the embodiment can be deleted.

For example, in the crystalline silicon solar cell 100 of the above embodiment, the second collecting electrode 8 is in contact with the single-crystal silicon substrate 2 in a part of the first overlapping region 111 and a part of the second overlapping region 112, but the second collecting electrode 8 may be separated from the single-crystal silicon substrate 2 through the first insulating layer 6 or the second insulating layer 7 in at least one of the entire region of the first overlapping region 111 and the entire region of the second overlapping region 112.

The material and shape of each layer constituting the solar battery cell 1 are not limited to those in the above embodiments. For example, the second connection electrode 9 of the above embodiment extends with the interval 90 therebetween in a direction substantially orthogonal to both the arrangement direction of the solar battery cells 1 and the thickness direction of the single crystal silicon substrate 2, but may extend without an interval therebetween.

In this case, the second collecting electrode is configured such that light is incident from the second main surface 22 side of the plurality of linear and lattice-shaped single crystal silicon substrates 2. In this case, the first main surface 21 of the single crystal silicon substrate 2 is a light receiving surface on one side, and the second main surface 22 is a light receiving surface on the other side.

As described above, according to the present invention, it is possible to provide a crystalline silicon solar cell having an optimized structure in which PERC type solar cells are stacked and connected.

The crystalline silicon solar cell of the present invention includes a solar cell string having a plurality of PERC-type solar cells, and the solar cell string is formed by overlapping and connecting two adjacent solar cells among the plurality of solar cells, each of the plurality of solar cells including: a single crystal silicon substrate of a unidirectional conductivity type having a first main surface and a second main surface; a diffusion layer of a reverse conductivity type in contact with the first main surface; a first collecting electrode in contact with the diffusion layer on a side opposite to a side in contact with the single crystal silicon substrate; a first connection electrode in contact with the diffusion layer and the first collecting electrode; an insulating layer in contact with the second main surface and having at least one opening penetrating therethrough; a second collecting electrode which is in contact with the insulating layer on a side opposite to a side in contact with the single-crystal silicon substrate and is connected to the single-crystal silicon substrate via the at least one opening portion; and a second connection electrode in contact with the second collecting electrode on a side opposite to a side in contact with the insulating layer, the first connection electrode and the second connection electrode being separated from each other when viewed from a direction substantially perpendicular to the first main surface in each of the plurality of solar battery cells, the solar battery string having an overlap region where the adjacent two solar battery cells overlap, the first connection electrode of one solar battery cell of the adjacent two solar battery cells being connected in an overlapping state with the second connection electrode of the other solar battery cell of the adjacent two solar battery cells when viewed from a direction substantially perpendicular to the first main surface in the overlap region, the first connection electrode being in contact with the second connection electrode of the other solar battery cell of the adjacent two solar battery cells in each of the plurality of solar battery cells in a majority of a portion of the overlap region or in an entire region of the overlap region, the second collecting electrode is separated from the single crystal silicon substrate via the insulating layer.

According to this configuration, since it is difficult to generate power in the overlap region that is shielded from light, even if the second collecting electrode for collecting carriers is not disposed in most of the overlap region, since the second collecting electrode is not disposed, the material consumption of the second collecting electrode can be suppressed accordingly. Thus, a crystalline silicon solar cell having an optimized structure can be provided.

In the crystalline silicon solar cell, the second collecting electrode of each of the plurality of solar battery cells may be disposed at least between an edge of the single crystal silicon substrate located on one side, which is a side where the second connection electrode is disposed in the arrangement direction of the plurality of solar battery cells in the solar battery string, and the second connection electrode.

According to this structure, carriers can be collected by the second collecting electrode without increasing the moving path from the single crystal silicon substrate, and therefore, dark current can be suppressed to improve the output, and resistance can be reduced to improve the output.

In the crystalline silicon solar cell, the second connection electrode and the single crystal silicon substrate may be separated from each other with the insulating layer interposed therebetween.

According to this configuration, since the second connection electrode is not in contact with the single crystal silicon substrate, recombination of minority carriers generated by the contact can be suppressed, and reduction in lifetime can be suppressed.

In the crystalline silicon solar cell, the first main surface may be a light-receiving surface.

With this structure, the crystalline silicon solar cell can be applied to a general PERC type solar cell.

In the crystalline silicon solar cell, in each of the plurality of solar battery cells, an edge of the single-crystal silicon substrate on one side, which is a side in the array direction of the plurality of solar battery cells in the solar battery string on which the second connection electrode is arranged, may have a surface substantially perpendicular to the first main surface and a slope formed by laser light irradiation when each of the plurality of solar battery cells is formed, and a distance between the edge of the second collecting electrode on the one side and the surface substantially perpendicular to the first main surface of the single-crystal silicon substrate may be 150% or more of a width of the slope in the array direction.

According to this configuration, when the semi-finished product (assembled battery) of the solar battery cell is irradiated with the laser light for cutting in the process of manufacturing the solar battery cell, the second collecting electrode is located at a position away from the irradiation site of the laser light, and thus is less likely to be damaged.

In the crystalline silicon solar cell, in each of the plurality of solar battery cells, a distance between an end edge of the second collecting electrode on the other side, which is the side on which the first connecting electrode is arranged in the arrangement direction of the plurality of solar battery cells in the solar battery string, and an end edge of the single crystal silicon substrate on the other side may be 40% or more and 90% or less of a size of the overlapping region in the arrangement direction.

In the crystalline silicon solar cell, a distance between an end edge of the second collecting electrode on the other side, which is a side where the first connecting electrode is arranged in the arrangement direction of the plurality of solar battery cells in the solar battery string, and an end edge of the single crystal silicon substrate on the other side may be 0.4mm or more in each of the plurality of solar battery cells.

According to this structure, in the process of manufacturing the solar cell string, when the solar cell units are connected in a stacked manner, for example, a metal paste is applied between the first connection electrode and the second connection electrode connected to each other in the adjacent solar cell units. In this case, even if the metal paste overflows from the portion of one solar cell to which the metal paste is applied to the back surface side, the edge of the second collecting electrode on the other side in the array direction is retreated inward (one side in the array direction) from the edge of the other side in the single crystal silicon substrate, and therefore, it is difficult for the first connecting electrode and the second collecting electrode to be connected by the metal paste, and thus, electric leakage occurs.

In the crystalline silicon solar cell, the second connection electrode is disposed at an interval in a direction substantially orthogonal to both the arrangement direction of the plurality of solar battery cells in the solar battery string and the thickness direction of the single crystal silicon substrate, and the opening of the insulating layer is disposed in a region of the second connection electrode at the interval.

According to this configuration, since the second connection electrodes are separated, a current can be made to flow from each opening to the adjacent second connection electrode, and therefore, the resistance can be reduced and the output can be further improved.

An assembled cell of a crystalline silicon solar cell according to the present invention is an assembled cell of a crystalline silicon solar cell assembled by a plurality of small sections, each of which is divided into a plurality of solar cells of a PERC type, the assembled cell having one side and an opposite side of the one side, each of the plurality of small sections being divided by a dividing line which is a straight line substantially parallel to the one side of the assembled cell, each of the plurality of small sections having: a single crystal silicon substrate of a unidirectional conductivity type having a first main surface and a second main surface; a diffusion layer of a reverse conductivity type in contact with the first main surface; a first collecting electrode in contact with the diffusion layer on a side opposite to a side in contact with the single crystal silicon substrate; a first connection electrode in contact with the diffusion layer and the first collecting electrode; an insulating layer in contact with the second main surface and having at least one opening penetrating therethrough; a second collecting electrode which is in contact with the insulating layer on a side opposite to a side in contact with the single-crystal silicon substrate and is connected to the single-crystal silicon substrate via the at least one opening portion; and a second connection electrode contacting the second collecting electrode on a side opposite to a side contacting the insulating layer, in each of the plurality of small segments, the first connection electrode is separated from the second connection electrode when viewed from a direction substantially perpendicular to the first main face, the second collecting electrode is separated from the one side of the assembled battery and from an opposite side of the one side of the assembled battery as viewed from a direction substantially perpendicular to the second main face, in a small cell including the one side of the assembled battery among the plurality of small cells, the second connection electrode is provided along the dividing line away from the one side of the assembled battery, in a cell including the opposite side of the assembled battery among the plurality of cells, the second connection electrode is disposed along the dividing line away from the opposite side of the assembled battery.

According to this configuration, when the life of minority carriers is short at the end of the assembled battery, and the small segments of the assembled battery are separated from each other and the small segments are connected to each other in a stacked manner as the solar battery cells, the stacked connection can be performed such that the portions of the assembled battery that are one side and the opposite side are located in the overlapping region where the solar battery cells overlap each other. In this case, since light is shielded in the overlapping region, it is difficult to generate electricity, and therefore, the influence on the output can be suppressed.

Description of reference numerals

1 … solar cell unit, 2 … single crystal silicon substrate, 3 … diffusion layer, 4 … first collecting electrode, 5 … first connecting electrode, 6 … first insulating layer, 7 … second insulating layer (insulating layer), 8 … second collecting electrode, 9 … second connecting electrode, 10 … solar cell string, 11 … overlapping region, 12 … assembled cell, 13 … metal paste, 21 … first main surface, 22 … second main surface, 23 … base portion, 24 … one end edge, 25 … other end edge, 26 … end portion, 31 … surface, 70 … opening portion, 81 … one end edge, 82 … other end edge, 90 … spacing, 100 … solar cell, 111 … first overlapping region, 112 … second overlapping region, 120 … small partition, 121 … position edge, 122 opposite edge, 124 dividing line …, … vertical surface (crystalline silicon splitting surface), … L oblique surface …, … L size, w … width.