JP3083987B2 - Solar cell module - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar cell module which is arranged on a roof of a house and performs photovoltaic power generation.

[0002]

2. Description of the Related Art A solar cell module for a building material having a flat plate shape has been proposed as a solar cell module arranged on the roof of a general house to generate solar power.

A conventional solar cell module for building materials is shown in FIG.
As shown in FIG. 6, between the front transparent substrate 1 made of tempered glass or the like and the back metal substrate 5 made of a coated steel plate, a stainless steel plate or the like, electrically connected in series or in parallel by connection leads 28 such as solder or copper foil. A plurality of solar cells 2... Made of crystalline silicon or the like are connected, and stacked with an adhesive interposed therebetween.

In the solar cell module for building materials, from the viewpoint of low cost and mass productivity, a sheet made of ethylene vinyl acetate resin (hereinafter, referred to as EVA) is arranged on the back metal substrate 5, and the solar cell is placed thereon. Cell 2, EVA
The sheet and the front surface transparent substrate 5 are sequentially placed, and hot-pressed under reduced pressure to be integrally formed.

By the way, in the solar cell 2 using single crystal silicon, a large number of V-shaped recesses are formed in the silicon substrate for the purpose of sufficiently absorbing light. In some cases, the light is confined by effectively utilizing the reflected light due to the letter-shaped concave portion.

[0006] The solar cell using single crystal silicon is, for example, a silicon ingot pulled up by the CZ method, except for a portion containing a large amount of impurities, for about 10 to 10 minutes.
A single-crystal silicon wafer cut into 15 cm squares and sliced along the (100) plane is used. This single crystal silicon is anisotropically etched by an alkaline aqueous solution such as NaOH. That is, depending on the crystal plane orientation,
The etching rate of silicon is very different, (111)
Since the etching rate of the plane is much lower than that of other crystal plane directions, anisotropic etching is performed on silicon by using an alkaline aqueous solution such as NaOH.

[0007] Therefore, by etching a silicon wafer sliced on the (100) plane using an alkaline aqueous solution such as NaOH, silicon is anisotropically etched along the (111) plane, and the silicon surface has a depth on the wafer surface. 1 to
An inverted pyramid-shaped concave portion of about 10 μm is uniformly formed on the entire surface. That is, an inverted square pyramid having a V-shaped cross section constituted by four walls oriented in the (111) plane is uniformly formed on the entire surface.

In the silicon wafer sliced on the (100) plane, the angle between the substrate surface and the wall oriented on the (111) plane is the same in all four directions.

[0009]

As described above, in the conventional solar cell module, a plurality of solar cells having the same shape are arranged between the front transparent substrate and the rear metal substrate, so that the solar cells are not illuminated. All reflections are reflected in the same manner, and the luminance, color, and appearance due to the reflection are configured in the same manner.

However, from the point of view of design, the visible appearance of the solar cell module is not all the same,
In some cases, a pattern or the like is preferable, and various external appearances of the solar cell module are desired.

SUMMARY OF THE INVENTION An object of the present invention is to provide a solar cell module in which a pattern can be formed on a solar cell module depending on the incident angle of light, in view of the above-mentioned conventional problems.

[0012]

A solar cell module according to the present invention is a solar cell module having a plurality of solar cells electrically connected to each other between a front transparent substrate and a back substrate. A first single unit having a plane sliced by a predetermined crystal plane as the plurality of solar cells;
Crystal silicon substrate and a slice plane of the first substrate
Single-crystal silicon having planes sliced at different angles
And at least two types of solar cells composed of a substrate and an anisotropic element.
A large number of recesses are formed on the surface of the substrate on the light incident side by the etching .

Further , at least one of the above solar cells is provided.
In one solar cell , a concave portion in which the angle between the wall in the first direction and the surface of the substrate and the angle between the wall in the second direction different from the first direction and the surface of the substrate are different from each other is light incident. What is necessary is just to use the board | substrate formed in many sides.

A plurality of solar cells are arranged in a matrix, and at least one solar cell is formed of another solar cell in which the angle between the wall of the recess and the surface of the substrate is arranged in the horizontal or vertical direction. It is good to arrange it so that it may differ from the crevice of a cell.

For example, by etching a single-crystal silicon substrate sliced on the (100) plane using an alkaline aqueous solution such as NaOH, silicon becomes (11).
1) Anisotropic etching is performed along the plane. Then, an inverted pyramid-shaped concave portion having a V-shaped cross section in which all the angles between the substrate surface and the wall of the (111) plane are equal is formed uniformly over the entire surface.

When the substrate sliced at a certain angle with respect to the (100) plane is also etched using an alkaline aqueous solution such as NaOH, the sectional shape of the concave portion formed on the substrate surface becomes (100) The V-shaped angle of the recess differs from that of the substrate sliced on the surface. That is, since the sliced plane has a predetermined angle from the (100) plane, the plane orientation of the surface changes, the angle of the (111) plane to be anisotropically etched changes depending on the direction, and the left and right or up and down of the substrate. Changes the angle between the wall of the (111) plane of the recess and the substrate surface.

As described above, when a substrate having a different cross-sectional shape of the concave portion formed in the substrate is used, the light reflection angle differs depending on the type of the substrate. Therefore, depending on the type of the substrate, it can be changed to look bright or dark depending on the incident angle of light.

When a solar cell using a substrate having a different slice plane is arranged between a transparent substrate and a metal plate in an appropriate order, the color of the cell changes subtly depending on the angle at which sunlight shines. The battery module appears to have a pattern.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a p-type silicon ingot pulled up by the CZ method is cut into a prism 20 of about 10 to 15 cm square except for a portion containing a large amount of impurities. Thereafter, the wafer is sliced along the (100) plane indicated by A in the figure to obtain a wafer of 300 to 500 μm. The first solar cell of this embodiment uses this wafer as a substrate.

As described above, single crystal silicon is made of NaO
Etching is anisotropic with an alkaline aqueous solution such as H. That is, since the etching rate of silicon greatly differs depending on the crystal plane orientation, and the etching rate of the (111) plane is much lower than that of other crystal plane orientations, silicon is different by using an alkaline aqueous solution such as NaOH. An isotropic etching is performed.

In the first solar cell of this embodiment, the silicon wafer 21 sliced on the (100) plane
After etching and cleaning the surface of
The silicon is anisotropically etched along the (111) plane by performing etching with a NaOH aqueous solution for about 40 minutes, and the inverted pyramid having a depth of about 1 to 10 μm is formed on the surface of the wafer 21 as shown in FIG. A concave portion 22a having a V-shaped cross section, that is, a concave portion 22a having a V-shaped cross section is formed uniformly over the entire surface. That is, the four walls 23 oriented in the (111) plane
22a having a V-shaped inverted quadrangular pyramid in cross section
Are uniformly formed on the entire surface.

The cross section of the surface of the substrate 21 and (111)
The angles formed by the plane-oriented walls 23 are the same in all four directions.

The second solar battery cell used in the embodiment of the present invention has a p-type silicon prism 20 cut into a size of about 10 to 15 cm as shown in FIG.
A wafer sliced at a certain angle with respect to the (100) plane is used. In this embodiment, as shown by B in the figure, a 300-500 μm wafer sliced at an angle of 20 degrees with respect to the (100) plane is used as a substrate.

In the second solar cell according to this embodiment, the silicon wafer 21 sliced at an angle of 20 degrees with respect to the (100) plane is etched and cleaned as described above. About a few percent of Na at about 80 ° C
Etching is performed with an OH aqueous solution for about 40 minutes. As a result of this etching, silicon is anisotropically etched along the (111) plane. As shown in FIG. 3, the silicon is substantially formed of four walls oriented to the (111) plane with a depth of about 1 to 10 μm, as shown in FIG. The V-shaped recess 22b is formed uniformly over the entire surface. As shown in FIG. 3, the cross-sectional shape of the concave portion 23 formed on the surface of the substrate 21 is an angle A between the wall 23a in the first direction and the surface of the substrate, and the first direction and the direction of line symmetry. The angle B between the wall 23b and the substrate surface in the second direction is different. That is, since the sliced surface is inclined at a predetermined angle from the (100) plane, the plane orientation of the surface changes and the angle of the (111) plane to be anisotropically etched changes.
The cross-sectional shape of the recess differs from that of the wafer sliced on the (100) plane.

Further, as shown in FIG. 1, the third solar cell used in the embodiment of the present invention has a p-type silicon prism 20 cut into a size of about 10 to 15 cm, as shown in FIG.
With respect to the (00) plane, a wafer C of 300 to 500 μm sliced at an angle of −20 degrees in the drawing, which is an angle inverted from the second solar cell, is used as a substrate.

In the third solar cell of this embodiment, the surface of the silicon wafer 21 sliced at an angle of -20 degrees with respect to the (100) plane was etched and cleaned in the same manner as described above. Later, about 80% of N at about 80%
Etching is performed with an aOH aqueous solution for about 40 minutes. As a result of this etching, silicon is anisotropically etched along the (111) plane, and as shown in FIG. 4, the silicon is oriented on the (111) plane with a depth of about 1 to 10 μm.
A substantially V-shaped concave portion 22c composed of individual walls is uniformly formed on the entire surface. As shown in FIG. 4, the cross-sectional shape of the concave portion 22c formed on the surface of the substrate 21 has an angle A formed between the wall 23c in the first direction and the substrate surface, and the angle A between the first direction and the line-symmetric direction. Angle B between wall 23d and substrate surface in direction 2
Is different. That is, since the sliced plane is inclined at a predetermined angle from the (100) plane, the plane orientation of the surface changes,
Since the angle of the (111) plane to be anisotropically etched changes, the cross-sectional shape of the recess changes from that of the wafer sliced on the (100) plane.

The recesses 23b and 23 shown in FIGS.
As shown in the figure, c has a relationship in which the left and right are reversed in the figure.

As described above, a PN junction is formed on the anisotropically etched wafer, a reflection film, a current collector, a busper electrode and the like are formed to form three types of solar cells. The formation of these solar cells will be briefly described with reference to FIG.

First, a p-type silicon ingot is placed in (10
A wafer 21 sliced on a slice plane having a predetermined angle with respect to the (0) plane and the (100) plane, in this embodiment, 20 degrees and −20 degrees is prepared (see FIG. 5A).

Then, after the surface of the wafer is etched and cleaned, anisotropic etching is performed for about 40 minutes with an aqueous solution of NaOH at about 80 ° C. of about several percent (see FIG. 5B). The wafer is etched on the surface having the cross-sectional shape of FIGS. 3 and 4 according to the slice plane.

Thereafter, phosphorus (P) diffusion is performed at a temperature of about 850 ° C., whereby an n-layer 24 having a depth of about 0.4 μm is formed on the wafer surface of 300 to 500 μm, and a PN junction is formed. (See FIG. 5 (c)).

After removing the silicon oxide 25 on the surface of the n-layer 24 with hydrofluoric acid (see FIG. 5D), an excess of the n-layer 24 is removed.
Is etched to perform junction separation (see FIG. 5E).
Thereafter, an antireflection film 25 such as titanium oxide (TiO ₂ ) is formed.
Is provided on the light incident side (see FIG. 5F).

Subsequently, a silver (Ag) paste is printed, the paste is baked, and a collector electrode 26 and a bus bar electrode 27 are provided to form a solar cell (FIG. 5).
(G)).

In the solar cell of the present invention, the cross-sectional shape of the concave portion formed on the substrate surface changes depending on the direction of the slice surface, and the cross-sectional shape of the concave portion may change when the solar cell is turned upside down or upside down. is there. For example, when the solar cell of FIG. 3 is inverted, it has the same cross-sectional shape as the solar cell of FIG. For this reason, when these solar cells are arranged in a matrix to form a solar cell module, it is necessary to pay attention to the orientation of each solar cell. For this purpose, for example, as shown in FIG.
It is better to add 9 so that the direction and the type of cell can be understood.

Then, a plurality of solar cells are electrically connected to form a module. First, the individual cells are connected by conducting wires with solder, for example, 64 solar cells of 8 × 8 rows. Are connected in series. Then, as shown in FIG. 7, the back metal substrate 5, the EVA sheet 6, the plurality of electrically connected solar cells 2, the EVA sheet 7, and the front transparent substrate 1 are placed in this order, and under reduced pressure. It is integrally formed by hot pressing.

An example of manufacturing the solar cell module for building material will be described with reference to FIG. In a lower chamber 33 of a vacuum container separated into an upper chamber 32 and a lower chamber 33 by a flexible sheet 31,
A sample 34 on which a back metal substrate, an EVA sheet, a solar cell, an EVA sheet, and a front transparent substrate are sequentially placed is arranged, and the pressure in both the upper chamber 32 and the lower chamber 33 is reduced by a vacuum pump 35. An O-ring 36 is arranged between the upper chamber 32 and the lower chamber 33. The sample 34 is heated by the heater 37.
Is heated to about 100 ° C. to melt the EVA sheet.

Next, the upper chamber 32 is leaked to atmospheric pressure. At this time, the sheet 31 separating the upper chamber 32 and the lower chamber 33 is pressed against the sample 34 by a pressure difference between the upper chamber 32 and the lower chamber 33, whereby the components are tightly integrated. Finally, heat the sample 34 at 150 ° C. for about 30 minutes,
Is crosslinked (stabilized). Thereby, the solar cell module for building materials described above is obtained.

By the way, as shown in FIG. 9A, in a solar cell having a concave portion 22b shape as shown in FIG.
The cells appear bright. In this case, there is not much difference from the case of the reflection of the solar cell having the shape of FIG. 2, and it looks like a normal solar cell. Conversely, as shown in FIG. 2 (b), when light is applied from the left side in the figure, it becomes dark and can be distinguished from ordinary solar cells.

Using this principle, in the modularization of the solar cell, the orientation of the solar cell is controlled, for example, as shown in the arrangement of FIG. 10, the solar cell of FIG. 3 and the solar cell of FIG. Are arranged on a checkered pattern to create a solar cell module. In the figure, the solar cell indicated by b is a solar cell having the shape shown in FIG. 3, and the solar cell indicated by c is a solar cell having the shape shown in FIG. Then, it laminates like a normal module, and attaches a terminal box, a frame, etc.

With this arrangement, a checkerboard-shaped solar cell module in which normal solar cells and dark solar cells alternately appear as shown in FIG. 11 when light shines from the right direction. Also, if the light hits from the left,
As shown in FIG. 12, a checkered pattern opposite to that of FIG. 11 is obtained. In this way, the pattern changes with time and light, and various designs can be enjoyed.

As shown in FIG. 13, three types of cells are arranged to form a solar cell module. In the figure, the solar cell indicated by a is a solar cell having the shape shown in FIG. 2, the solar cell indicated by b is a solar cell having the shape shown in FIG. 3, and the solar cell indicated by c is shown in FIG. It is a solar cell of the shape shown.

In the solar cell module shown in FIG. 13, when light strikes from the right, the solar cell indicated by b becomes dark, and the two solar cells indicated by a and c reflect light of the same degree. Therefore, as shown in FIG. 14, the number "11" becomes visible. Conversely, when light hits from the left, the solar cell indicated by c becomes dark as shown in FIG. 15, and the two solar cells indicated by a and b are reflected by the same degree of light, so the number “6” is indicated. Will be visible.

In the embodiment described above, the solar cells having the cross-sectional shapes shown in FIGS.
Although wafers sliced at two slice planes of 20 degrees and −20 degrees with respect to the (100) plane are used, as described above, when the solar cell of FIG.
It has the same cross-sectional shape as that of the solar cell. Therefore, (10
0) The cross-sectional shape of the concave portion on the substrate can be changed vertically or horizontally by preparing one that inverts the direction of a solar cell using a wafer sliced at a predetermined angle with respect to the plane and one that does not. Can be different. For example, in the arrangement of the solar cell module of FIG.
The same configuration can be achieved by alternately arranging solar cells using wafers sliced on one slice plane having a predetermined angle from the (100) plane, with the direction being inverted and not. .

[0045]

As described above, according to the present invention, the color of the solar cell changes slightly depending on the angle of sunlight, and the solar cell module appears to have a pattern, and the design is rich in variety. A solar cell module is obtained.

By calculating the angle of sunlight and the color of the photovoltaic cells, it is possible to represent characters, symbols, and the like that change with time.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a slice surface of a wafer of a solar cell used in the present invention.

FIG. 2 is a schematic diagram showing a cross-sectional shape of a solar cell used in the present invention.

FIG. 3 is a schematic diagram showing a cross-sectional shape of a solar cell used in the present invention.

FIG. 4 is a schematic diagram showing a cross-sectional shape of a solar cell used in the present invention.

FIG. 5 is a sectional view illustrating each step of the method for manufacturing a solar cell used in the present invention.

FIG. 6 is a plan view of a solar cell used in the present invention.

FIG. 7 is an exploded sectional view of the solar cell module of the present invention.

FIG. 8 is a schematic cross-sectional view showing an apparatus for manufacturing a solar cell module.

FIG. 9 is a diagram showing the relationship between the direction of light and the reflection of a solar cell used in the present invention.

FIG. 10 is a diagram showing an arrangement state of solar cells in the solar cell module of the present invention.

FIG. 11 is a schematic diagram showing a state in which light hits the solar cell module shown in FIG. 10 from the right side.

FIG. 12 is a schematic diagram showing a state in which light has hit the solar cell module shown in FIG. 10 from the left side.

FIG. 13 is a view showing an arrangement state of solar cells in the solar cell module of the present invention.

FIG. 14 is a schematic view showing a state in which light has hit the solar cell module shown in FIG. 13 from the right side.

FIG. 15 is a schematic diagram showing a state in which light has hit the solar cell module shown in FIG. 13 from the left side.

FIG. 16 is a sectional view showing a solar cell module.

[Explanation of symbols]

 Reference Signs List 1 front transparent substrate 2 solar cell 5 back metal substrate 21 substrate 22 concave portion

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinyuki Tsujino 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Kenji Oda 2-chome, Keihanhondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd. (72) Inventor Kenji Uchihashi 2-5-5 Keihanhondori, Moriguchi City, Osaka Prefecture Sanyo Electric Co., Ltd. (72) Inventor Takashi Fujiwara 1-1-1, Hama, Amagasaki City, Hyogo Prefecture Inside the Kubota Research and Development Laboratory Co., Ltd. (72) Inventor Hiroshi Yamakawa 1-1-1 Hama, Amagasaki City, Hyogo Prefecture Inside Kubota Technology Development Laboratory Co., Ltd. (56) References JP2 76269 (JP, A) JitsuHiraku Akira 55-152071 (JP, U) (58 ) investigated the field (Int.Cl. ^7, DB name) H01L 31/04 - 31/078

Claims (3)

(57) [Claims] 1. A solar cell module having a plurality of solar cells electrically connected to each other between a front transparent substrate and a rear substrate, wherein the plurality of solar cells are a predetermined crystal. The first with the plane sliced in plane
A single crystal silicon substrate and a slice plane of the first substrate
A second single crystal silicon having a plane sliced at a predetermined angle
And Con substrate, in conjunction with at least two kinds of solar cells were constructed is used, the solar cell is anisotropic
A solar cell module, wherein a large number of recesses are formed on the substrate surface on the light incident side by reactive etching . 2. The method of claim 1 , wherein at least one of the solar cells is
In the solar cell , a concave portion in which an angle formed between a wall in a first direction and a substrate surface and an angle formed between a wall in a second direction different from the first direction and a substrate surface is different from a light incident side. 2. The substrate according to claim 1, wherein a plurality of substrates are formed.
Solar module. 3. A solar cell in which a plurality of solar cells are arranged in a matrix, and at least one solar cell is arranged such that an angle between a wall of the concave portion and a substrate surface is arranged in a horizontal or vertical direction. The solar cell module according to claim 2, wherein the solar cell module is arranged so as to be different from a concave portion of the cell.