WO2022186274A1

WO2022186274A1 - Crystalline silicon solar battery cell, solar battery device, and solar battery module

Info

Publication number: WO2022186274A1
Application number: PCT/JP2022/008864
Authority: WO
Inventors: 崇口山; 徹寺下
Original assignee: 株式会社カネカ
Priority date: 2021-03-03
Filing date: 2022-03-02
Publication date: 2022-09-09

Abstract

Provided is a crystalline silicon solar battery cell with which it is possible to suppress a reduction in strength caused by formation of a through hole. The present invention is a crystalline silicon solar battery cell (2) comprising: a crystalline silicon substrate (11); and an electroconductive silicon-based thin film formed on a main surface of the crystalline silicon substrate (11), said crystalline silicon solar battery cell (2) having a light-receiving surface that receives incident light, and a back surface on the opposite side from the light-receiving surface, and also having a plurality of through holes (40) that pass from the light-receiving surface to the back surface and transmit light. The plurality of through holes (40) are arrayed in two dimensions along one or a plurality of arraying lines on the light-receiving surface and the back surface, the arraying lines being non-parallel to the crystalline surfaces (A1, A2) of the crystalline silicon substrate (11).

Description

CRYSTALLINE SILICON SOLAR CELL, SOLAR BATTERY DEVICE AND SOLAR MODULE

The present invention relates to a crystalline silicon solar cell, a solar cell device, and a solar cell module.

As a solar battery cell, a thin film solar battery cell using an inorganic thin film such as an amorphous silicon thin film or an organic thin film such as a perovskite thin film (more specifically, an organic/inorganic hybrid thin film) in the photoelectric conversion part, and a photoelectric conversion part A crystalline silicon solar cell using a crystalline silicon substrate is known. Among such solar cells, there is a demand for a light transmission type (hereinafter also referred to as a see-through type) solar cell that allows a portion of light to pass therethrough, even if the power generation output is somewhat sacrificed.

Patent Documents

1 and 2 disclose a thin-film solar cell, which is a see-through type solar cell having a large number of through holes. On the other hand, Patent Literatures 3 and 4 disclose techniques related to see-through type solar cells which are crystalline silicon solar cells and have a large number of through holes. In particular, Patent Documents 3 and 4 disclose techniques for forming a large number of through holes in a crystalline silicon substrate.

In addition, recently, when modularizing solar cells, there is a method in which parts of the solar cells are overlapped to directly connect them electrically and physically. Such a connection method is called a single ring method, and a plurality of solar cells electrically connected by the single ring method is called a solar battery string (solar battery device) (see, for example, Patent Document 5).

In solar cell strings (solar cell devices), more solar cells can be mounted in the limited solar cell mounting area of a solar cell module. Better output.

By the way, as described above, there is a demand for a light transmission type (hereinafter also referred to as a see-through type) solar cell that allows a portion of light to pass through, even if the power generation output is somewhat sacrificed. In this regard, Patent Literature 5 discloses a see-through solar cell having a large number of through holes.

JP-A-5-129642 JP-A-2000-31514 Japanese Patent Application Laid-Open No. 2002-299672 WO2003/072500 JP 2011-171542 A

In a crystalline silicon solar cell, the crystalline silicon substrate has a crystal plane (crystal orientation). Since the bonding force between atoms is weak on the crystal plane, the crystalline silicon substrate has the property of being relatively fragile along the crystal plane. Due to this property, the crystal plane (crystal orientation) is also called a cleavage plane (cleavage direction). If a large number of through-holes are formed in a crystalline silicon substrate having such characteristics, it is expected that the strength of the crystalline silicon substrate will decrease, and as a result, the strength of the crystalline silicon solar cell will decrease.

Also, when partially overlapping see-through solar cells using a single ring method (singling structure), it is necessary to overlap the ends of the solar cells so that the through holes are not blocked. Therefore, depending on the width from the edge of the solar battery cell to the through hole, the overlapping width of the edge of the solar battery cell (corresponding to the width from the edge of the solar battery cell to the through hole) cannot be secured sufficiently. It is expected that the strength of the ring structure will decrease.

An object of the present invention is to provide a crystalline silicon solar cell capable of suppressing a decrease in strength due to the formation of through holes.
Another object of the present invention is to provide a crystalline silicon solar cell, a solar cell device, and a solar cell module capable of suppressing a reduction in the strength of the shingling structure due to the formation of through holes.

A crystalline silicon solar cell according to the present invention is a crystalline silicon solar cell comprising a crystalline silicon substrate and a conductive silicon thin film formed on the main surface of the crystalline silicon substrate, and receives incident light. and a back surface opposite to the light receiving surface, and a plurality of through holes penetrating from the light receiving surface to the back surface and transmitting light. The plurality of through holes are two-dimensionally arranged along one or more arrangement lines on the light receiving surface and the back surface, and the arrangement lines are non-parallel to the crystal plane of the crystalline silicon substrate. is.

Another crystalline silicon solar cell according to the present invention is a crystalline silicon solar cell comprising a crystalline silicon substrate and a conductive silicon thin film formed on the main surface of the crystalline silicon substrate, wherein incident light and a back surface opposite to the light receiving surface, and a plurality of through holes penetrating from the light receiving surface to the back surface and transmitting light. The plurality of through-holes are arranged two-dimensionally on the light-receiving surface and the back surface, and at least one row of the plurality of through-holes extends along at least one end of the crystalline silicon solar cell. Each of the through-holes in one row has a partially cut-out shape.

A solar cell device according to the present invention is a solar cell device comprising the plurality of crystalline silicon solar cells described above, wherein two adjacent crystalline silicon solar cells among the plurality of crystalline silicon solar cells wherein the one end of one crystalline silicon solar cell has a shingling structure overlapping the other end of the other crystalline silicon solar cell, and the one end of the one crystalline silicon solar cell One row of through-holes overlaps with the through-holes of the other crystalline silicon solar cell.

A solar cell module according to the present invention comprises one or more of the above solar cell devices, a light-receiving-side protective member for protecting the light-receiving surface side of the solar cell device, and the back surface of the solar cell device opposite to the light-receiving surface side. a back side protection member for protecting a plurality of solar cell devices; and a sealing material. The through-holes of the plurality of crystalline silicon-based solar cells in the solar cell device are partially filled with the sealing material.

ADVANTAGE OF THE INVENTION According to this invention, the fall of the intensity|strength of a crystalline-silicon-type solar cell resulting from formation of a through-hole can be suppressed.
Moreover, according to the present invention, it is possible to suppress a decrease in the strength of the shingling structure of the crystalline silicon solar cell due to the formation of the through holes.

It is the figure which looked at the solar cell which concerns on 1st Embodiment from the back surface side. FIG. 2 is an end view of the photovoltaic cell shown in FIG. 1 taken along line II-II. FIG. 2 is an enlarged view of part III of the solar cell shown in FIG. 1; FIG. 10 is a view of a solar cell module including a solar cell device according to a second embodiment, viewed from the back side; 5 is a cross-sectional view of the solar cell module shown in FIG. 4 taken along the line V-V. FIG. It is the figure which looked at the solar cell which concerns on 2nd Embodiment from the back surface side. FIG. 7 is a VII-VII line end view of the solar cell shown in FIG. 6 ; It is a figure which shows an example of division|segmentation of the crystalline silicon substrate of 2nd Embodiment. It is a figure which shows an example of division|segmentation of the crystalline silicon substrate of a comparative example.

An example of an embodiment of the present invention will be described below with reference to the accompanying drawings. In each drawing, the same reference numerals are given to the same or corresponding parts. Also, for convenience, hatching, member numbers, etc. may be omitted, but in such cases, other drawings shall be referred to.

[First Embodiment]
FIG. 1 is a view of the solar cell according to the first embodiment as seen from the back side, and FIG. 2 is an end view of the solar cell shown in FIG. 1 taken along line II-II. The solar cell 2 shown in FIGS. 1 and 2 is a crystalline silicon-based solar cell comprising a crystalline silicon substrate 11 having two main surfaces. Hereinafter, the main surface of the crystalline silicon substrate 11 on the light receiving side is referred to as the light receiving surface, and the main surface of the crystalline silicon substrate 11 opposite to the light receiving surface is referred to as the rear surface.

The solar cell 2 comprises an intrinsic silicon-based thin film 23, a first conductivity type silicon-based thin film 25 and a first electrode layer 27 which are laminated in order on the light receiving surface side of the crystalline silicon substrate 11. The solar cell 2 also includes an intrinsic silicon-based thin film 33 , a second conductivity type silicon-based thin film 35 and a second electrode layer 37 which are laminated in order on the back side of the crystalline silicon substrate 11 .

The crystalline silicon substrate 11 is made of a crystalline silicon material such as monocrystalline silicon or polycrystalline silicon. The crystalline silicon substrate 11 is, for example, an n-type crystalline silicon substrate in which a crystalline silicon material is doped with an n-type dopant. Examples of n-type dopants include phosphorus (P). The crystalline silicon substrate 11 functions as a photoelectric conversion substrate that absorbs incident light from the light receiving surface side and generates photocarriers (electrons and holes).

Since crystalline silicon is used as the material of the crystalline silicon substrate 11, dark current is relatively small, and relatively high output (stable output regardless of illuminance) can be obtained even when the intensity of incident light is low. .

The intrinsic silicon-based thin film 23 is formed on the light receiving surface side of the crystalline silicon substrate 11 . The intrinsic silicon-based thin film 33 is formed on the back side of the crystalline silicon substrate 11 . The intrinsic silicon-based

thin films

23 and 33 are formed of a material containing, for example, intrinsic (i-type) amorphous silicon as a main component. The intrinsic silicon-based

thin films

23 and 33 function as passivation layers, suppress recombination of carriers generated in the crystalline silicon substrate 11, and increase carrier recovery efficiency.

The first conductivity type silicon-based thin film 25 is formed on the intrinsic silicon-based thin film 23 , that is, on the light receiving surface side of the crystalline silicon substrate 11 . The first conductivity type silicon-based thin film 25 is made of, for example, an amorphous silicon material. The first conductivity type silicon-based thin film 25 is a p-type silicon-based thin film in which, for example, an amorphous silicon material is doped with a p-type dopant. Examples of p-type dopants include boron (B).

The second conductivity type silicon-based thin film 35 is formed on the intrinsic silicon-based thin film 33 , that is, on the back side of the crystalline silicon substrate 11 . The second conductivity type silicon-based thin film 35 is made of, for example, an amorphous silicon material. The second conductivity type silicon-based thin film 35 is an n-type silicon-based thin film in which, for example, an amorphous silicon material is doped with an n-type dopant (for example, phosphorus (P) described above).

The first conductivity type silicon thin film 25 may be an n-type silicon thin film, and the second conductivity type silicon thin film 35 may be a p-type silicon thin film. Alternatively, the crystalline silicon substrate 11 may be a p-type crystalline silicon substrate in which a crystalline silicon material is doped with a p-type dopant (for example, boron (B) described above).

The first electrode layer 27 is formed on the first conductivity type silicon-based thin film 25 , that is, on the light receiving surface side of the crystalline silicon substrate 11 . The second electrode layer 37 is formed on the second conductivity type silicon thin film 35 , that is, on the back side of the crystalline silicon substrate 11 . The first electrode layer 27 and the second electrode layer 37 may include a transparent electrode layer and a metal electrode layer, or may include only the metal electrode layer. In the first embodiment, the first electrode layer 27 includes a transparent electrode layer 28 and a metal electrode layer 29 , and the second electrode layer 37 includes a transparent electrode layer 38 and a metal electrode layer 39 .

The transparent electrode layers 28, 38 are made of a transparent conductive material. Transparent conductive materials include ITO (Indium Tin Oxide: composite oxide of indium oxide and tin oxide) and ZnO (Zinc Oxide). The metal electrode layers 29 and 39 are made of metal material. For example, Cu, Ag, Al, and alloys thereof are used as the metal material. The metal electrode layer may be formed of, for example, a conductive paste material containing metal powder such as silver.

The first electrode layer 27 is formed on the light-receiving surface side of the crystalline silicon substrate 11 in a region between through-holes 40 to be described later. For example, the first electrode layer 27 is formed in a grid pattern on the light receiving surface side of the crystalline silicon substrate 11 . Similarly, the second electrode layer 37 is formed on the rear surface side of the crystalline silicon substrate 11 in a region between through holes 40 to be described later. For example, the second electrode layer 37 is formed in a grid pattern on the back side of the crystalline silicon substrate 11 .

The solar cell 2 has a plurality of through-holes 40 penetrating from the light-receiving surface to the back surface. The plurality of through holes 40 are arranged two-dimensionally on the light receiving surface and the back surface. Thereby, the solar cell 2 can transmit light from the light receiving surface side to the back surface side via the through hole 40 .

On the light-receiving surface, the ratio of the plurality of through-holes 40 to the substantially power-generating area (that is, aperture ratio) is 3% or more and 50% or less. As a result, light can be transmitted from the light-receiving surface side to the back surface side without greatly reducing the power generation output of the solar cell 2 .

The shape of the through-hole 40 is not limited to circular, and may be polygonal. The through hole 40 has a shape having a center or center of gravity inside the periphery. The through hole 40 does not have a function of electrical connection between the light receiving surface and the back surface. That is, the through hole 40 does not have a conductive film formed on its inner wall, unlike known through holes for electrically connecting the light receiving surface and the back surface.

Here, the crystalline silicon substrate has a crystal plane (crystal orientation). For example, as shown in FIG. 1, in a square (rectangular) or semi-square (octagonal octagon obtained by cutting the four corners of a square) crystalline silicon substrate (wafer), two crystal planes (crystal orientation ) A1, A2. Since the bonding force between atoms is weak on the crystal plane, the crystalline silicon substrate has the property of being relatively fragile along the crystal plane. Due to this property, the crystal plane (crystal orientation) is also called a cleavage plane (cleavage direction).

Therefore, when the through-holes 40 are formed such that the array lines of the through-holes 40 are parallel to the crystal planes A1 and A2 of the crystalline silicon substrate 11, the crystalline silicon substrate 11 is aligned along the crystal planes A1 and A2. It is expected that the crystalline silicon substrate 11 will be easily cracked and the strength of the crystalline silicon substrate 11 will be reduced. As a result, it is expected that the strength of the solar battery cell 2 will decrease.

Regarding this point, in the first embodiment, the through holes 40 are formed as follows. FIG. 3 is an enlarged view of the III portion of the solar cell 2 shown in FIG. As shown in FIG. 3, the plurality of through holes 40 are regularly arranged along the plurality of arrangement lines B1, B2, B3 on the light receiving surface and the back surface. The arrangement lines B1, B2, B3 are straight lines connecting the centroids or the centers of the through holes 40 .

The array lines B1, B2, B3 are non-parallel to the crystal planes A1, A2 of the crystalline silicon substrate 11. For example, if one of the plurality of through-holes 40 is a target through-hole and m through-holes (m is an integer equal to or greater than 2) adjacent to the target through-hole are adjacent through-holes, the target through-hole and m Each of the m/2 array lines along which each of the adjacent through-holes extends is non-parallel to the crystal planes A1 and A2 of the crystalline silicon substrate 11 . Referring to FIG. 3, more specifically, one of the plurality of through holes 40 is a target through hole 40t, and two of the six through holes adjacent to the target through hole 40t are the first through holes. Assuming the adjacent through-hole 40a1 and the second adjacent through-hole 40a2, the first array line B1 along which the target through-hole 40t and the first adjacent through-hole 40a1 are aligned and the second array line B1 along which the target through-hole 40t and the second adjacent through-hole 40a2 are aligned. The arrangement line B2 is non-parallel to the crystal planes A1 and A2 of the crystalline silicon substrate 11 .

More specifically,
Let θ0 be the angle formed by the two crystal planes A1 and A2 of the crystalline silicon substrate 11 on the light-receiving surface and the back surface,
- One of the plurality of through-holes 40 is defined as a target through-hole 40t, and two of m through-holes (m is an integer equal to or greater than 2) adjacent to the target through-hole 40t are selected as first adjacent ones. When the through-hole 40a1 and the second adjacent through-hole 40a2 are formed, on the light-receiving surface and the back surface, a first arrangement line B1 along which the target through-hole 40t and the first adjacent through-hole 40a1 extend, and a second adjacent through-hole 40t and the target through-hole 40t. Let θ1 be the angle formed by the through hole 40a2 and the second array line B2 along which
If the angle between the first array line B1 and the crystal plane A1 on the light-receiving surface and the back surface is greater than or equal to the angle between the second array line B2 and the crystal plane A1, the first array line B1 and the crystal plane Let θ be the angle between the surface A1 and
- Let r be the maximum distance from the center of gravity or the center of the target through-hole 40t to the periphery,
Let d be the distance between the center of gravity or the center of the target through-hole 40t and the center of gravity or the center of the first adjacent through-hole 40a1,
If the number of corners of the polygon forming the periphery of the plurality of through-holes 40 is n (n is an integer of 3 or more), and the polygon includes a circle (in the case of a circle, n=∞),
The plurality of through holes 40 are arranged so as to satisfy the following formulas (1) to (4).
0<θ≦θmax (1)
d>2r (2)
tan(θ1/2)>r (3)

By satisfying the above formula (1), when the through holes 40 are formed, the crystal planes (cleavage planes) A1 and A2 of the crystalline silicon substrate 11 and the array lines B1, B2 and B3 of the through holes 40 to which stress is applied are aligned. As a result, breakage of the crystalline silicon substrate 11 is less likely to occur. Here, the upper limit value .theta.max is obtained by the above equation (4). Moreover, the target through-hole 40t and the adjacent through-holes 40a1 and 40a2 are separated from each other by satisfying the expression (2). Further, by satisfying the above formula (3), the first adjacent through-hole 40a1 and the second adjacent through-hole 40a2 are separated from each other.

Six adjacent through-holes with respect to the target through-hole satisfy the above expressions (1) to (4), and all of the plurality of through-holes satisfy the above (1) to (4) of the target through-hole and the adjacent through-holes. By satisfying the relationship of the formula, the plurality of array lines B1, B2 and B3 are non-parallel to the crystal planes A1 and A2 of the crystalline silicon substrate 11 as described above.

As described above, according to the solar cell 2 of the first embodiment, the arrangement lines B1, B2 and B3 of the through holes 40 are arranged non-parallel to the crystal planes A1 and A2 of the crystalline silicon substrate 11. , through holes 40 are formed. This can prevent the crystalline silicon substrate 11 from being easily cracked along the crystal planes A1 and A2 even when the through holes 40 are formed, and can prevent the strength of the crystalline silicon substrate 11 from decreasing. . Therefore, a decrease in the strength of the solar battery cell 2 can be suppressed.

Although the first embodiment of the present invention has been described above, the present invention is not limited to the above-described first embodiment, and various changes and modifications are possible. For example, in the above-described first embodiment, a see-through solar cell in which a plurality of through holes are formed in a double-sided electrode solar cell is exemplified. However, the present invention is not limited to this, and can also be applied to a see-through solar cell in which a plurality of through holes are formed in a back electrode type (also referred to as back contact type or back contact type) solar cell. be. A back electrode type solar cell includes a crystalline silicon substrate, a first conductivity type silicon thin film and a second conductivity type silicon thin film formed on the back surface of the crystalline silicon substrate, and a light receiving surface of the crystalline silicon substrate. and a silicon-based compound thin film (optical adjustment layer, antireflection layer). Even in such a back electrode type solar cell, the above-described through holes penetrating from the light receiving surface to the back surface may be formed.

Also, in the above-described first embodiment, the solar cell in which the plurality of through holes are regularly arranged along the plurality of arrangement lines was exemplified. However, the method of arranging through-holes of the present invention, particularly the arranging method of formulas (1) to (4) above, is not limited to this, and the solar cells are regularly arranged along one or more arrangement lines. It is also applicable to cells or solar cells randomly arranged along one or more arrangement lines.

Further, in the first embodiment described above, the heterojunction solar cell is exemplified as shown in FIG. However, the present invention is not limited to this, and can be applied to various solar cells such as homojunction solar cells.

[Second embodiment]
(solar cell module)
FIG. 4 is a view of a solar cell module including a solar cell device according to the second embodiment, viewed from the back side, and FIG. 5 is a cross-sectional view of the solar cell module shown in FIG. 4 taken along line VV. In FIG. 4, a light-receiving side protective member 3, a back side protective member 4, a sealing material 5, and a connecting member 6, which will be described later, are omitted. An XY orthogonal coordinate system is shown in FIGS. 4 and 5 and drawings to be described later. The XY plane is a plane along the light receiving surface and the back surface of the solar cell module.

As shown in FIGS. 4 and 5, the solar cell module 100 includes a solar cell device (also referred to as a solar cell string) 1 that electrically connects a plurality of solar cells 2A using a shingling method.

The solar cell device 1 is sandwiched between the light receiving side protective member 3 and the back side protective member 4 . A liquid or solid sealing material 5 is filled between the light-receiving-side protective member 3 and the back-side protective member 4 , thereby sealing the solar cell device 1 .

The encapsulant 5 seals and protects the solar battery device 1, that is, the solar battery cell 2A. And, it is interposed between the back surface of the solar battery device 1 and the solar battery cell 2</b>A and the back surface protective member 4 . The shape of the sealing material 5 is not particularly limited, and may be, for example, a sheet shape. This is because the sheet shape facilitates covering the front and back surfaces of the planar solar battery cell 2A.

Although the material of the sealing material 5 is not particularly limited, it is preferable that the material has the property of transmitting light (translucency). Moreover, it is preferable that the material of the encapsulant 5 has adhesiveness to bond the photovoltaic cell 2</b>A, the light-receiving side protective member 3 and the back side protective member 4 . Examples of such materials include ethylene/vinyl acetate copolymer (EVA), ethylene/α-olefin copolymer, ethylene/vinyl acetate/triallyl isocyanurate (EVAT), polyvinyl butyrate (PVB), acrylic Translucent resins such as resins, urethane resins, and silicone resins can be used.

The light-receiving-side protective member 3 covers the surface (light-receiving surface) of the solar battery device 1, that is, the solar battery cell 2A through the encapsulant 5 to protect the solar battery device 1 and the solar battery cell 2A. The shape of the light-receiving-side protective member 3 is not particularly limited, but a plate-like or sheet-like shape is preferable from the point of indirectly covering the planar light-receiving surface.

Although the material of the light-receiving side protective member 3 is not particularly limited, it is preferable to use a material that has translucency and is resistant to ultraviolet light, similar to the sealing material 5. For example, glass, or Transparent resins such as acrylic resins and polycarbonate resins can be used. Further, the surface of the light-receiving-side protective member 3 may be processed into an uneven shape, or may be coated with an antireflection coating layer. This is because the light-receiving-side protective member 3 having such a configuration makes it difficult to reflect the received light, and guides more light to the solar cell device 1 .

The back side protection member 4 covers the back surface of the solar battery device 1, that is, the solar battery cell 2A through the encapsulant 5 to protect the solar battery device 1 and the solar battery cell 2A. The shape of the back side protection member 4 is not particularly limited, but like the light receiving side protection member 3, it is preferably plate-like or sheet-like in that it indirectly covers the planar back side.

The material for the back side protection member 4 is not particularly limited, but a material that prevents the infiltration of water or the like (has high water impermeability) is preferable. For example, a resin film such as polyethylene terephthalate (PET), polyethylene (PE), olefin-based resin, fluorine-containing resin, or silicone-containing resin, or a translucent plate-shaped resin member such as glass, polycarbonate, or acrylic, A laminate with a metal foil such as an aluminum foil may be mentioned.

(solar cell device)
In the solar battery device 1, the solar battery cells 2A are connected in series by partially overlapping the ends of the solar battery cells 2A. Specifically, one of the adjacent

solar cells

2A, 2A on one side of the photovoltaic cell 2A in the Y direction (for example, the right end side in FIG. 5) is part of the light receiving surface side of the other solar cell. It overlaps under a part of the back side of the other end side (for example, the left end side in FIG. 5) of the cell 2A in the Y direction.

In this way, a plurality of solar cells 2A are uniformly inclined in a certain direction like a tiled roof, so that the solar cells 2A are electrically connected in this way. The method is called the shingling method. A plurality of solar cells 2A connected in a string is called a solar cell string (solar cell device). Below, the area|region where adjacent

solar cell

2A and 2A overlap is called overlap|superposition area|region Ro.

Adjacent

photovoltaic cells

2A, 2A are bonded via connection member 6 in overlapping region Ro. As the connection member 6, a known interconnector such as a tab and/or a conductive adhesive member is used. The conductive adhesive member includes a conductive film formed of a thermosetting resin film containing low-melting metal particles or metal fine particles, a conductive adhesive formed of low-melting metal fine particles or metal fine particles and a binder, or , a solder paste containing solder particles, or the like is used.
The solar cell 2A in the solar cell device 1 will be described below.

(solar battery cell)
FIG. 6 is a view of the solar cell 2A in the solar cell device 1 shown in FIGS. 4 and 5 as seen from the back side, and FIG. 7 is an end view of the solar cell 2A taken along line VII-VII of FIG. . A solar cell 2A shown in FIGS. 6 and 7 is a crystalline silicon-based solar cell having a crystalline silicon substrate 11A having two main surfaces. Hereinafter, the main surface of the crystalline silicon substrate 11A on the light receiving side is referred to as the light receiving surface, and the main surface of the crystalline silicon substrate 11A opposite to the light receiving surface is referred to as the back surface.

The solar cell 2A comprises an intrinsic silicon thin film 23A, a first conductivity type silicon thin film 25A and a first electrode layer 27A which are laminated in order on the light receiving surface side of the crystalline silicon substrate 11A. The solar cell 2A also includes an intrinsic silicon-based thin film 33A, a second conductivity type silicon-based thin film 35A and a second electrode layer 37A, which are sequentially laminated on the back side of the crystalline silicon substrate 11A.

The crystalline silicon substrate 11A is made of a crystalline silicon material such as monocrystalline silicon or polycrystalline silicon. The crystalline silicon substrate 11A is, for example, an n-type crystalline silicon substrate in which a crystalline silicon material is doped with an n-type dopant. Examples of n-type dopants include phosphorus (P). The crystalline silicon substrate 11A functions as a photoelectric conversion substrate that absorbs incident light from the light receiving surface side and generates photocarriers (electrons and holes).

Since crystalline silicon is used as the material of the crystalline silicon substrate 11A, dark current is relatively small, and relatively high output (stable output regardless of illuminance) can be obtained even when the intensity of incident light is low. .

The intrinsic silicon-based thin film 23A is formed on the light receiving surface side of the crystalline silicon substrate 11A. The intrinsic silicon thin film 33A is formed on the back side of the crystalline silicon substrate 11A. The intrinsic silicon-based

thin films

23A and 33A are formed of a material containing, for example, intrinsic (i-type) amorphous silicon as a main component. The intrinsic silicon-based

thin films

23A and 33A function as passivation layers, suppress recombination of carriers generated in the crystalline silicon substrate 11A, and increase carrier recovery efficiency.

The first conductivity type silicon-based thin film 25A is formed on the intrinsic silicon-based thin film 23A, that is, on the light receiving surface side of the crystalline silicon substrate 11A. The first conductivity type silicon-based thin film 25A is made of, for example, an amorphous silicon material. The first conductivity type silicon-based thin film 25A is, for example, a p-type silicon-based thin film in which an amorphous silicon material is doped with a p-type dopant. Examples of p-type dopants include boron (B).

The second conductivity type silicon-based thin film 35A is formed on the intrinsic silicon-based thin film 33A, that is, on the back side of the crystalline silicon substrate 11A. The second conductivity type silicon-based thin film 35A is made of, for example, an amorphous silicon material. The second conductivity type silicon-based thin film 35A is an n-type silicon-based thin film in which, for example, an amorphous silicon material is doped with an n-type dopant (for example, phosphorus (P) described above).

The first conductivity type silicon thin film 25A may be an n-type silicon thin film, and the second conductivity type silicon thin film 35A may be a p-type silicon thin film. Alternatively, the crystalline silicon substrate 11A may be a p-type crystalline silicon substrate in which a crystalline silicon material is doped with a p-type dopant (for example, boron (B) described above).

The first electrode layer 27A is formed on the first conductivity type silicon thin film 25A, that is, on the light receiving surface side of the crystalline silicon substrate 11A. The second electrode layer 37A is formed on the second conductivity type silicon thin film 35A, that is, on the back side of the crystalline silicon substrate 11A. 27 A of 1st electrode layers and 37 A of 2nd electrode layers may contain a transparent electrode layer and a metal electrode layer, and may contain only a metal electrode layer. In the second embodiment, the first electrode layer 2A7 includes a transparent electrode layer 28A and a metal electrode layer 29A, and the second electrode layer 37A includes a transparent electrode layer 38A and a metal electrode layer 39A.

The

transparent electrode layers

28A, 38A are made of a transparent conductive material. Transparent conductive materials include ITO (Indium Tin Oxide: composite oxide of indium oxide and tin oxide) and ZnO (Zinc Oxide). The metal electrode layers 29A, 39A are made of a metal material. For example, Cu, Ag, Al, and alloys thereof are used as the metal material. The metal electrode layer may be formed of, for example, a conductive paste material containing metal powder such as silver.

The first electrode layer 27A is formed in a region between through holes 40A, which will be described later, on the light receiving surface side of the crystalline silicon substrate 11A. For example, the first electrode layer 27A is formed in a grid pattern on the light receiving surface side of the crystalline silicon substrate 11A. Similarly, the second electrode layer 37A is formed on the back surface side of the crystalline silicon substrate 11A in a region between through holes 40A, which will be described later. For example, the second electrode layer 37A is formed in a grid pattern on the back surface side of the crystalline silicon substrate 11A.

(Details of solar cells)
As shown in FIGS. 6 and 7, the solar cell 2A has a plurality of through holes 40A penetrating from the light receiving surface to the back surface. The plurality of through holes 40A are arranged two-dimensionally on the light receiving surface and the back surface. Thereby, the photovoltaic cell 2A can transmit light from the light receiving surface side to the back surface side via the through hole 40A.

On the light-receiving surface, the ratio of the plurality of through-holes 40A to the power-generating area that can substantially generate power (that is, the aperture ratio) is 3% or more and 50% or less. As a result, light can be transmitted from the light-receiving surface side to the back surface side without greatly reducing the power generation output of the solar cell 2A.

The shape of the through-hole 40A is not limited to circular and may be polygonal. 40 A of through-holes are shapes which have a center or a center of gravity in the inside of a peripheral edge. 40 A of through-holes do not have the electrical connection function of a light-receiving surface and a back surface. That is, the through hole 40A does not have a conductive film formed on the inner wall, unlike known through holes for electrically connecting the light receiving surface and the back surface.

One row of the plurality of through-holes 40A arranged in the X direction is aligned along one end (right end: one end) of the solar cell 2A. Each of the through-holes 40A in one row has a partially cut-out shape. Another row of the plurality of through holes 40A arranged in the X direction is aligned along the other end (left end: other end) of the solar cell 2A. Each of the through-holes 40A may have a partially cut-out shape.

(Details of solar cell devices)
As shown in FIGS. 4 and 5, one end (right end: one end) in the Y direction of one of the adjacent

solar cells

2A, 2A is the Y direction of the other solar cell 2A. It overlaps under the other end (left end: other end) in the direction (singling structure). In the overlapping region Ro, one row of through-holes 40A at one end (one end) of one solar cell 2A overlaps with the first row of through-holes 40A from the other end (other end) of the other solar cell 2A. overlapping.

As described above, according to the solar cell device 1 and the solar cell module 100 of the second embodiment, one end of one of the adjacent

solar cells

2A, 2A (for example, FIG. 5 A plurality of photovoltaic cells 2A are electrically connected using a shingling method such that the right end in FIG. be. As a result, more solar cells 2A can be mounted in the limited solar cell mounting area of the solar cell device 1 and the solar cell module 100, the light receiving area for photoelectric conversion increases, and the solar cell device 1 And the output of the solar cell module 100 is improved.

Here, when the solar cell 2A having a plurality of through-holes 40A has a shingling structure, it is necessary to overlap the ends of the solar cell 2A so that the through-holes 40A are not blocked. Therefore, depending on the width from the edge of the photovoltaic cell 2A to the through hole 40A, the overlapping width of the edge of the photovoltaic cell 2A (corresponding to the width from the edge of the photovoltaic cell 2A to the through hole 40A) should be sufficiently secured. It is expected that the strength of the shingling structure will decrease.

FIG. 8 is a diagram showing an example of division of the crystalline silicon substrate of the second embodiment, and FIG. 9 is a diagram showing an example of division of the crystalline silicon substrate of the comparative example. As described above, in the single ring structure, one of the divided large-sized semiconductor substrates having a predetermined size is used as the crystalline silicon substrate 11A. A predetermined size is a size determined by a predetermined size (for example, 6 inches) of a crystalline silicon wafer. For example, in the case of a 6-inch large crystal silicon substrate, the large crystal silicon substrate is divided into 2 or more and 10 or less pieces in one predetermined direction.

As shown in FIG. 9, when cutting along the cutting line L2 between the through-holes 40A, as described above, depending on the width from the edge of the solar cell 2A to the through-hole 40A, the ends of the solar cells 2A overlap. It is expected that the width Ro (corresponding to the width from the edge of the solar cell 2A to the through hole 40A) cannot be secured sufficiently, and the strength of the shingling structure is reduced.

Regarding this point, in the second embodiment, as shown in FIG. 8, the through hole 40A is cut along the cutting line L1. As a result, the overlapping width Ro of the end portion of the solar cell 2A (corresponding to the width from the edge of the solar cell 2A to the through hole 40A) can be increased compared to FIG.

As described above, according to the solar cell 2A of the second embodiment, as shown in FIG. 6, the through holes 40A are arranged up to the edge of the solar cell 2A, and part of the through holes 40A are cut out. As shown in FIGS. 4 and 5, the edge through-holes 40A can overlap with the through-holes 40A of the adjacent solar cells 2A. In other words, the width from the edge of the photovoltaic cell 2A to the through-hole 40A in the row next to the through-hole 40A at this edge can be widened. Therefore, the overlapping width Ro of the edge of the solar cell 2A (equivalent to the width from the edge of the solar cell 2A to the through-hole 40A in the row next to the through-hole 40A at this edge) can be widened. A decrease in the strength of the shingling structure of the battery device 1 can be suppressed.

Further, according to the solar cell 2A of the second embodiment, since it is a see-through type solar cell in which a through hole is formed in the crystalline silicon solar cell, a see-through type solar cell in which a through hole is formed in the thin film solar cell. It is possible to provide a see-through type solar cell with a higher output than the solar cell of the above.

Here, in manufacturing a solar cell module, when laminating (heating and pressurizing) the light-receiving side protective member and the back side protective member, the solar cell device, and the encapsulant, the solar cells in the solar cell device are displaced from each other. In order to prevent this, fixing tapes are sometimes applied to the solar cell devices during layup. This fixing tape degrades the design of the solar cell module. In addition, the process of attaching the fixing tape increases the number of manufacturing processes of the solar cell module, resulting in an increase in the cost of the solar cell module.
In addition, in the solar cell module 100 of the second embodiment, as shown in FIG. 5, the through holes 40A of the solar cells 2A are partially filled with the sealing material 5 .

Regarding this point, according to the solar cell module 100 of the second embodiment, the plurality of through holes 40A are formed in the solar cell 2A. and the sealing material 5 are laminated (heated and pressurized), a part of the sealing material 5 enters the through hole 40A of the solar cell 2A. As a result, the solar cells 2A are fixed, and displacement between the solar cells 2A in the solar cell device 1 is suppressed. This eliminates the need for a fixing tape during lay-up, preventing deterioration in the design of the solar cell module. In addition, it is possible to prevent an increase in the number of manufacturing processes for the solar cell module, thereby preventing an increase in the cost of the solar cell module.

Further, in the solar cell module 100 of the second embodiment, unevenness may be formed on the surface of the inner wall of the through hole 40A of the solar cell 2A. For example, by forming the through hole 40A using a laser, the surface roughness of the inner wall of the through hole 40A is 1.0 μm or more and 10.0 μm or less. Thereby, the surface area of the inner wall of the through hole 40A is increased, and the adhesion between the inner wall of the through hole 40A and the sealing material 5 is improved. Therefore, the deviation between the solar cells 2A in the solar cell device 1 is further suppressed. Moreover, the durability of the single ring structure of the solar cell device 1 against temperature changes is improved, and the reliability of the solar cell module 100 is improved.

Moreover, in the solar cell module 100 of the second embodiment, the through holes 40A of the solar cells 2A are partially filled with the sealing material 5, and the adhesion between the solar cells 2A and the sealing material 5 is improved. , the encapsulant can be made thinner. As a result, the weight of the solar cell module 100 can be reduced. For example, generally, the thickness of the encapsulant between the light-receiving side protective member and the solar cell and the thickness of the encapsulant between the back side protective member and the solar cell are 300 μm to 600 μm. On the other hand, according to the second embodiment, in order to obtain similar performance, the thickness of the encapsulant 5 between the light-receiving side protective member 3 and the solar cell 2A and the thickness of the back side protective member 4 The thickness of the sealing material 5 between the solar cells 2A can be reduced to 50 μm or more and 200 μm or less.

Also, in the solar cell module 100 of the second embodiment, it is preferable that the thickness of the solar cell 2A is thin. Thereby, the through-hole 40A of the solar cell 2A can be reliably filled with the sealing material 5 . For example, typically the thickness of a solar cell is between 120 μm and 200 μm. On the other hand, according to the second embodiment, the thickness of the solar cell 2A is preferably 50 μm or more and 150 μm or less.

Although the second embodiment of the present invention has been described above, the present invention is not limited to the above-described second embodiment, and various changes and modifications are possible. For example, in the above-described second embodiment, a see-through solar cell in which a plurality of through holes are formed in a double-sided electrode solar cell is exemplified. However, the present invention is not limited to this, and can also be applied to a see-through solar cell in which a plurality of through holes are formed in a back electrode type (also referred to as back contact type or back contact type) solar cell. be. A back electrode type solar cell includes a crystalline silicon substrate, a first conductivity type silicon thin film and a second conductivity type silicon thin film formed on the back surface of the crystalline silicon substrate, and silicon formed on the light receiving surface of the crystalline silicon substrate. and a compound thin film (optical adjustment layer, antireflection layer). Even in such a back electrode type solar cell, the above-described through holes penetrating from the light receiving surface to the back surface may be formed.

In addition, in the above-described second embodiment, the solar cell module 100 includes a single solar cell device 1, but the solar cell module 100 may include a plurality of solar cell devices 1 arranged in the X direction, for example. You may prepare.

Further, in the above-described second embodiment, the solar cell device 1 including the heterojunction solar cell 2A as shown in FIG. 7 is exemplified. However, the present invention is not limited to this, and can be applied to solar cell devices including various solar cells such as homojunction solar cells.

1 Solar cell device (solar cell string)
2, 2A solar battery cell 3 light-receiving side protective member 4 back side protective member 5 sealing material 6 connecting

member

11, 11A

crystalline silicon substrate

23, 33, 23A, 33A intrinsic silicon-based

thin film

25, 25A first conductivity type silicon-based

thin film

27 , 27A

first electrode layer

28, 38, 28A, 38A

transparent electrode layer

29, 39, 29A, 39A

metal electrode layer

35, 35A second conductivity type silicon

thin film

37, 37A

second electrode layer

40, 40A through hole 40t object Through hole 40a1 First adjacent through hole (adjacent through hole)
40a2 Second adjacent through-hole (adjacent through-hole)
A1, A2 Crystal plane B1 First array line (array line)
B2 Second array line (array line)
B3 array line 100 solar cell modules

Claims

A crystalline silicon solar cell comprising a crystalline silicon substrate and a conductive silicon thin film formed on a main surface of the crystalline silicon substrate,
The crystalline silicon solar cell is
Having a light receiving surface for receiving incident light and a back surface opposite to the light receiving surface,
having a plurality of through-holes penetrating from the light-receiving surface to the back surface and transmitting light;
the plurality of through-holes are arranged two-dimensionally along one or more arrangement lines on the light-receiving surface and the back surface;
the array line is non-parallel to the crystal plane of the crystalline silicon substrate;
A crystalline silicon solar cell.
One of the plurality of through-holes is a target through-hole, m through-holes adjacent to the target through-hole are adjacent through-holes, and m is an integer of 2 or more,
Each of the m/2 array lines along which the target through hole and each of the m adjacent through holes are aligned is non-parallel to the crystal plane of the crystalline silicon substrate.
The crystalline silicon solar cell according to claim 1.
The crystalline silicon solar cell according to claim 1 or 2, wherein the arrangement line is a line connecting the centers of gravity of the through holes.
The crystalline silicon solar cell according to claim 3, wherein each of the plurality of through-holes has a shape having a center of gravity inside the periphery.
The crystalline silicon system according to any one of claims 1 to 4, wherein a ratio of the plurality of through holes to a power generation region substantially capable of generating power on the light receiving surface is 3% or more and 50% or less. solar cell.
The crystalline silicon solar cell according to any one of claims 1 to 5, wherein said plurality of through-holes do not have an electrical connection function between said light receiving surface and said back surface.
A crystalline silicon solar cell comprising a crystalline silicon substrate and a conductive silicon thin film formed on a main surface of the crystalline silicon substrate,
The crystalline silicon solar cell is
Having a light receiving surface for receiving incident light and a back surface opposite to the light receiving surface,
having a plurality of through-holes penetrating from the light-receiving surface to the back surface and transmitting light;
the plurality of through-holes are arranged two-dimensionally on the light-receiving surface and the back surface;
at least one row of the plurality of through-holes is arranged along at least one end of the crystalline silicon solar cell;
Each of the rows of through-holes has a partially cut-out shape,
A crystalline silicon solar cell.
The crystalline silicon solar cell according to claim 7, wherein a ratio of said plurality of through-holes to a power generation region substantially capable of generating power on said light receiving surface is 3% or more and 50% or less.
The crystalline silicon solar cell according to claim 7, wherein said plurality of through-holes do not have an electrical connection function between said light receiving surface and said back surface.
A solar cell device comprising a plurality of crystalline silicon solar cells according to any one of claims 7 to 9,
In two adjacent crystalline silicon solar cells among the plurality of crystalline silicon solar cells, the one end of one crystalline silicon solar cell overlaps the other end of the other crystalline silicon solar cell. It has a shingling structure,
the one row of through-holes at the one end of the one crystalline silicon-based solar cell overlaps with the through-holes of the other crystalline silicon-based solar cell,
solar device.
one or more solar cell devices according to claim 10;
a light-receiving side protection member that protects the light-receiving surface side of the solar cell device;
a back side protection member that protects the back side of the solar cell device opposite to the light receiving side;
a sealing material disposed between the solar cell device and the light-receiving side protective member and between the solar cell device and the back side protective member to seal the plurality of solar cell devices;
with
The through-holes of the plurality of crystalline silicon-based solar cells in the solar cell device are partially filled with the sealing material,
solar module.