CN111727509A

CN111727509A - Solar cell module

Info

Publication number: CN111727509A
Application number: CN201980013226.6A
Authority: CN
Inventors: 寺下徹; 小泉玄介
Original assignee: Kaneka Corp
Current assignee: Kaneka Corp
Priority date: 2018-02-21
Filing date: 2019-02-19
Publication date: 2020-09-29
Anticipated expiration: 2039-02-19
Also published as: CN111727509B; WO2019163779A1; JP7349979B2; JPWO2019163779A1

Abstract

A solar cell module (100) is provided with: a plurality of solar cells (10) which are electrically connected; an encapsulating material (103) encapsulating the plurality of solar battery cells (10); and two protective members (105A, 105B) that sandwich the sealing material (103) from the two opposing main surface sides of the solar cell (10). Each solar cell (10) is provided with a gas layer (13) between at least one of the two main surfaces and the sealing material (103) facing the main surface.

Description

Solar cell module

Technical Field

The present invention relates to a solar cell module.

Background

With the increasing awareness of people on the environmental protection, the enthusiasm for developing net zero energy buildings (ZEH) and net Zero Energy Buildings (ZEB) is increasing. In order to realize the above-described ZEH and ZEB, it is necessary to produce required electric power from the building itself, and it is now studied to employ a solar cell module as a power generation unit.

Although the solar cell module is installed in a building, the solar cell module cannot supply necessary electric power only when installed on the roof of the building, and therefore, it is considered that the solar cell module is installed in a place other than the roof, and the technical development thereof is also progressing. For example, patent document 1 describes a solar cell integrated wall assembly, and patent document 2 describes a mount for mounting a solar cell module on a wall surface.

Patent document 1: japanese laid-open patent publication No. 2016 & 186156

Patent document 2: japanese laid-open patent publication No. 2016-

Disclosure of Invention

The present invention is a solar cell module including: a plurality of solar cells electrically connected to each other; an encapsulating material encapsulating the plurality of solar cell units; and two protective members that sandwich the sealing material from two opposing main surfaces of the solar battery cell together with the plurality of solar battery cells, wherein each of the solar battery cells is provided with an air layer between at least one of the two main surfaces and the sealing material opposing the main surface.

Drawings

Fig. 1 is a schematic partial cross-sectional view illustrating a solar cell module according to an embodiment.

Fig. 2 is a schematic cross-sectional view illustrating a control principle of controlling reflected light by the surface of a solar cell in a conventional solar cell module.

Fig. 3 is a schematic cross-sectional view showing a state of reflected light on the surface of a solar cell unit encapsulated by an encapsulating material in a conventional solar cell module.

Fig. 4 is a schematic cross-sectional view showing the state of reflected light on the surface of the solar cell in the solar cell module according to the embodiment.

Fig. 5 is a schematic cross-sectional view showing an example of roughening the surface on the inner side of a sheet covering a solar cell unit in the solar cell module according to the embodiment.

Fig. 6 is a schematic cross-sectional view showing one step in the method for manufacturing a solar cell module according to the embodiment.

Fig. 7 is a schematic partial cross-sectional view showing a solar cell module according to a modification of the embodiment.

Detailed Description

The embodiments and examples are described below with reference to the drawings. The following description of the embodiments and examples is illustrative and is not intended to limit the scope of the application or use. In the drawings, the dimensional ratios of the respective components are set for convenience in illustration, and do not indicate actual dimensional ratios.

Fig. 1 shows a schematic partial cross section of a solar cell module 100 (hereinafter, simply referred to as "module") according to an embodiment.

The module 100 according to the embodiment includes a solar cell string 10A in which a plurality of solar cells 10 (hereinafter, simply referred to as "cells") are electrically connected to each other via a wiring (tab line) 102. The solar cell string 10A (hereinafter, simply referred to as a "cell string") is, for example, an electrically connected unit (output unit) in which a plurality of cells 10 of about 15 are connected in series.

The upper surface (for example, the light-receiving surface on the light-receiving side of the two main surfaces of the battery cell 10), the lower surface (for example, the rear surface on the side opposite to the light-receiving surface) and the entire periphery of each battery cell 10 are sealed with a sealing material 103 formed of a first sealing material 103a and a second sealing material 103 b.

The sealing material 103 is sandwiched between the light-receiving-surface protective material 105A and the back-surface protective material 105B, which are two protective members. As the

protective materials

105A and 105B, for example, glass or a resin material is used.

The sealing process of the plurality of battery cells 10 with the sealing material 103 (the first sealing material 103a and the second sealing material 103b) can be performed, for example, as follows: a laminate in which the first sealing material 103a, the battery cell string 10A, the second sealing material 103B, and the back surface protective material 105B are placed in this order on the light-receiving surface protective material 105A is produced, and then the laminate is heated under predetermined conditions to be cured integrally as the sealing material 103.

In the present embodiment, as will be described later, the gas layer 13 is provided between the light-receiving-side main surface of each battery cell 10 and the first sealing material 103 a. As a result of the color tone of the light receiving surface of each battery cell 10 being displayed in this way, the module 100 according to the embodiment can control the color tone.

Next, a method of controlling the color tone of each battery cell 10 in the module 100 according to the embodiment will be described with reference to the drawings.

First, the surface of the silicon wafer included in the battery cell 10 has a color tone with low chroma such as gray. As shown in fig. 2, in the case where the outermost layer 11 is formed on the outermost surface of the cell 10 by, for example, an antireflection film, interference occurs in which the phase difference in the outermost layer 11 is reflected on the reflected light Ra of the incident light from the surface of the outermost layer 11 and the reflected light Rb of the incident light from the light receiving surface of the cell 10 (the wafer itself). As a result, the reflected light Ra and the reflected light Rb are mutually intensified or weakened by the wavelength reflecting the phase difference. That is, reflected light Ra formed based on the refractive index difference between the air and the outermost layer 11 and reflected light Rb formed based on the refractive index difference between the outermost layer 11 and the light receiving surface of the battery cell 10 interfere with each other, and appears to the human eye as color tones.

The phase difference between the reflected light Ra and the reflected light Rb is controlled by the film thickness and refractive index of the outermost layer 11. That is, by the design of the outermost layer 11, the color tone of the battery cell 10 can be controlled. Further, the closer the intensities of the reflected light Ra and the reflected light Rb are, the stronger the interference effect is, and the clearer the color tone is. For example, as shown in fig. 3, when the battery cell 10 having the outermost layer 11 is packaged with the packaging material 103, the intensity of the reflected light RA generated from the surface of the outermost layer 11 is smaller than the intensity of the reflected light RB generated from the surface of the battery cell 10, and the interference effect becomes weak.

Therefore, in the conventional module structure, as shown in fig. 3, the outermost layer 11 of the packaged battery cell 10 is in close contact with the packaging material 103, and therefore, the refractive index difference between the packaging material 103 and the outermost layer 11 is small, and the intensity of the reflected light RA is small. Therefore, the interference between the reflected light RA and the reflected light RB is weakened, and as a result, the reflected light RB of the battery cell 10 becomes a main body and a color close to black appears.

In contrast, as shown in fig. 4, in the module 100 according to the embodiment, a planar (lamellar) air layer 13 is provided between the sealing material 103 and the outermost layer 11 as an unbonded area where the sealing material 103 and the outermost layer 11 are not in close contact with each other. Thus, the difference between the refractive index of the reflected light RAA from the surface of the outermost layer 11 of the cell 10 and the refractive index of the reflected light RBB from the light-receiving surface of the cell 10 increases. Therefore, the interference effect between the reflected light RAA from the outermost layer 11 and the reflected light RBB from the light-receiving surface of the battery cell 10 is enhanced, and the battery cell 10 is modularized without impairing the desired color tone of the light-receiving surface color of the battery cell 10. That is, as shown in fig. 4, in the module 10, the outermost layer 11 is covered with the air layer 13, so that the intensity of the reflected light RAA generated from the outermost layer 11 and the intensity of the reflected light RBB generated from the light-receiving surface of the battery cell 10 are close to each other, and therefore, the color tone is also clear.

Here, as a method of providing the planar air layer 13 between the sealing material 103 and the outermost layer 11, as shown in fig. 4, a sheet 15 made of a transparent resin may be provided between the outermost layer 11 of the battery cell 10 and the sealing material 103. The sheet 15 is not particularly limited as long as it is in close contact with the sealing material 103 and not in close contact with the battery cell 10, that is, the outermost layer 11. Examples of the sheet 15 include polyethylene terephthalate, polyvinyl fluoride, and a fluorine resin sheet. The sheet 15 may be disposed on each battery cell 10 between the battery cell 10 and the first sealing material 103a, or may be disposed over the entire surface thereof in correspondence with the

protective materials

105A and 105B. The gas layer 13 is not particularly limited, and may be an air layer, a nitrogen gas layer, or the like.

The method of changing and adjusting the color of the light-receiving surface of the battery cell 10 is not particularly limited, and for example, the method of changing the film thickness of the outermost layer 11 of the battery cell 10 may be used. For example, as the battery cell 10, a back contact solar cell (back contact battery cell) may be used. In the back contact cell, a p-type semiconductor layer and an n-type semiconductor layer are alternately provided on the back surface side of a semiconductor substrate made of crystalline silicon or the like, and a passivation layer and an antireflection film are provided in this order from the substrate side on the light receiving surface side. By adjusting the film thickness of the antireflection film corresponding to the outermost layer 11, color adjustment can be easily performed.

The semiconductor substrate is formed of a single-conductivity-type single-crystal silicon substrate. Generally, a single crystal silicon substrate has an n-type in which an atom (e.g., phosphorus (P)) that introduces an electron to a silicon atom is doped, and a P-type in which a plate is doped with an atom (e.g., boron (B)) that supplies a hole to a silicon atom. The term "one conductivity type" as used herein means either n-type or p-type. That is, the semiconductor substrate is a single crystal silicon substrate having n-type or p-type conductivity.

In addition, when the structure is adopted in which the air layer 13 is provided between the first sealing material 103a on the light receiving surface side of the sealing material 103 and the battery cell 10 as in the present embodiment, as will be described later, propagation of a shock wave when a flying object such as a bird collides with the module 10 is suppressed. Therefore, it is possible to prevent the cell from being broken due to the shock wave, and as a result, it is possible to obtain the module 100 having high reliability while suppressing the performance degradation of the module 100.

As shown in fig. 5, the sheet 15 may be a sheet 15A having at least a surface opposite to the gas layer 13 roughened. By roughening the sheet 15A in such a manner as to have irregularities, light incident into the module 100 is reflected by the roughened surface, and a re-incident effect of light incident into the battery cell 10 is produced. Further, the inside of the sheet 15A is roughened, so that the gas layer 13 is easily provided.

The roughness of the roughened sheet 15A may be set to an arithmetic average roughness Ra₁Is 1 μm or more and 10 μm or less. In the case of the uneven shape, it is preferable to satisfy an embossed shape having a width of 0.5mm or more and 1.5mm or less, a length of 0.5mm or more and 1.5mm or less, and a depth of 0.01mm or more and 0.1mm or less, or a triangular shape in which the inclination angle of the inclined surface is set within a predetermined range.

[ modularization ]

As shown in fig. 1, in a module 100 according to the embodiment, a battery cell string 10A in which a plurality of battery cells 10 are connected by wiring 102 is sandwiched between a light-receiving-surface protective material 105A and a rear-surface protective material 105B via a sealing material 103. At least on the light-receiving surface of each cell 10, a sheet 15 is provided with a planar gas layer 13 interposed therebetween. For example, the battery cell string 10A can be packaged by placing the first sealing material 103a, the sheet 15, the battery cell string 10A, the second sealing material 103B, and the back surface protection material 105B in this order on the light-receiving surface protection material 105A to form a laminate, and heating the laminate under predetermined conditions to cure the sealing materials 103a and 103B.

As the sealing material 103, a transparent resin such as a polyethylene resin composition containing an olefin elastomer as a main component, polypropylene, an ethylene/α -olefin copolymer, an ethylene/vinyl acetate copolymer (EVA), ethylene/vinyl acetate/triallyl isocyanurate (EVAT), polyvinyl butyrate (PVB), silicon, polyurethane, acrylic, or epoxy is used. The first sealing material 103a on the light receiving surface side and the second sealing material 103b on the back surface side may be made of the same material or different materials.

The light-receiving-surface protective material 105A has light-transmitting properties, and for example, glass or transparent plastic is used.

On the other hand, the back surface protective material 105B has any one of light transmittance, light absorption, and light reflectance. The back surface protective material 105B having light reflectivity is preferably a metal color, a white color, or the like. For example, a white resin film or a laminate in which a metal foil such as aluminum is interposed between resin films is suitable as the rear surface protective material 105B.

As the light-absorbing back surface protective material 105B, for example, a member having a black appearance and including a black resin layer or the like is suitably used. When the back-contact battery cells 10 having, for example, a black light-receiving surface (cell surface) are modularized using the back-protective member 105B (e.g., black sheet) having light absorption properties, the back-protective member 105B and the battery cells 10 have similar colors in appearance, so that the gaps between the battery cell strings 10A are inconspicuous, and a module 100 having a high appearance is obtained.

In the battery cell string 10A, the adjacent battery cells 10 may have a roof structure (a shingled structure) such that a part of one battery cell 10A overlaps a part of the other battery cell 10B, which is not shown. When such a shingled configuration is employed, there is no gap between the battery cells 10 in the battery cell string 10A. Therefore, for example, when the module 100 having the laminated structure is formed by using the battery cells 10 having the black light-receiving surface, the appearance can be improved by unifying the cell surfaces on the light-receiving side of the module 100 to black. In such a module 100, for example, if the black-based rear surface protection member 105B is used, the entire light receiving side of the module 100 can be reliably made black, and therefore, the appearance can be further improved.

In the above description, the example of the battery cell 10 having the black light-receiving surface has been described, but the present invention is not limited to the black system, and for example, in the case of the module 100 using the battery cell 10 having the deep blue or deep green light-receiving surface (cell surface), the appearance color of the back surface protection member 105B and the color of the cell surface may be the same color. That is, if the cell surface color of the battery cell 10 and the appearance color of the back surface protection member 105B are made to be the same, the appearance of the module 100 can be improved.

[ examples ]

Examples and comparative examples are shown below.

[ production of Back-contact Battery cell ]

A back-contact cell was fabricated using a 6-inch n-type single crystal silicon substrate (Semi-square type with a side length of 156 mm) having a thickness of 160 μm, on which textures were formed on the opposite major surfaces. Silver paste was screen-printed on each of the n-type semiconductor layer and the p-type semiconductor layer as the metal electrode on the back surface, and then, the metal electrode was baked at a temperature of 150 ℃ for about 30 minutes.

A passivation layer and an antireflection film are formed in this order on the light-receiving surface. Silicon nitride (SiN) having a refractive index of 1.9 was formed in three film thicknesses of 45nm, 70nm and 165nm by a Chemical Vapor Deposition (CVD) method, and an antireflection film corresponding to the outermost layer 11 was obtained. The thickness of the antireflection film is a value on the inclined surface of the texture, and is obtained by measuring SiN deposited on a glass substrate by an ellipsometry method and converting the measured SiN into an inclined surface.

[ examples ]

A method for manufacturing the module 100 according to the embodiment will be described below with reference to fig. 6.

First, on white board glass as the light-receiving-surface protective material 105A, a first sealing material 103a made of ethylene/vinyl acetate copolymer (EVA) and a PET sheet as the sheet material 15 made of transparent resin are disposed in this order. Further, a plurality of battery cells 10 and a second encapsulant 103B made of EVA were placed, and a back sheet having a black resin layer 105a provided on a PET film 105B as a base material was disposed thereon as a back surface protective material 105B.

Then, after thermocompression bonding was performed for 5 minutes under atmospheric pressure, the EVA was held at 150 ℃ for 60 minutes to crosslink the EVA, thereby obtaining a module 100. In this case, the battery cells having the antireflection films with three thicknesses are modularized.

The PET sheet as the sheet 15 is placed on the first sealing material 103a uniformly and entirely, but is not limited thereto. That is, the PET sheet may be disposed so as to cover at least the light receiving surface (lower surface in fig. 6) of each battery cell 10. The gas layer 13 formed on the light-receiving surface of each battery cell 10 by a PET sheet may cover at least half of the area of the light-receiving surface of each battery cell 10. The same applies to the following comparative examples.

[ comparative example ]

A first sealing material made of EVA, a plurality of battery cells, and a second sealing material made of EVA are disposed on a white board glass as a light-receiving surface protective material. A back sheet having a black resin layer provided on a PET film as a base material is disposed thereon as a back surface protective material.

Then, after thermocompression bonding was performed for 5 minutes under atmospheric pressure, the EVA was crosslinked by holding at 150 ℃ for 60 minutes to obtain a module. Here, the battery cells having the antireflection films with three film thicknesses are also modularized.

As described above, the embodiment is different from the comparative example in that the sheet 15 for forming the gas layer 13 is disposed between the first sealing material 103a and the light receiving surface of the battery cell 10 in the embodiment.

[ color tone confirmation of solar cell and cell in Module ]

The light-receiving surface of each of the three types of battery cells 10 produced was observed, and the color tone was confirmed. The modules according to the examples and comparative examples were observed under sunlight. The color tone close to the color tone of the antireflection film passed through the battery cell 10 was evaluated by a, and the color tone close to the back sheet itself was evaluated by B, and the results are shown in table 1 below.

[ Table 1]

As is clear from the comparison of the examples and the comparative examples, in the comparative examples, the three kinds of battery cells 10 in the module are all similar in hue to the hue of the back sheet, that is, the black color, whereas in the examples, the module 100 in which the three kinds of battery cells 10 in the module are all similar in hue to the battery cells 10 can be produced. In the module structure of the comparative example, since the surfaces of the battery cells are in close contact with the sealing material, the difference in refractive index between the sealing material and the outermost surface layer of the battery cells is small. As a result, the reflected light generated on the outermost layer is reduced, and therefore, the interference light is weakened, and the reflected light generated on the light receiving surface of the battery cell is mainly reflected, and a color close to black appears.

In contrast, in the present embodiment, a planar gas layer 13 is provided between the sealing material 103 and the outermost layer 11 of the battery cell 10. The planar gas layer 13 increases the reflection light RAA generated by the outermost layer 11 and the reflection light RBB generated by the light-receiving surface of the cell 10 due to the difference in refractive index therebetween, and the reflection light RAA and the reflection light RBB due to the difference in refractive index interfere with each other. As a result, the module 100 is realized without impairing the color tone of the light receiving surface of the battery cell 10.

[ impact resistance of solar cell Module ]

Next, a description will be given of a case where the impact resistance of the module 100 of the example is improved as compared with the comparative example.

After the battery cell 10 having an antireflection film made of silicon nitride (SiN) and having a film thickness of 70nm was manufactured, the modules of the above-described examples and comparative examples were formed, and the impact resistance test was performed. Weights of 1.5kg, 2.6kg and 4.8kg were dropped from a height of 80cm, and whether or not cracks were observed in the battery cells 10 in each module was confirmed by Photoluminescence (PL). As the result of the confirmation, the case where no crack was observed was evaluated by a, and the case where a crack was observed was evaluated by B, and the results are shown in the following [ table 2 ].

[ Table 2]

In the impact resistance test, when the examples and comparative examples are compared, cracks were observed in the battery cell 10 for weights of 2.6kg and 4.8kg in the comparative examples. On the other hand, in the embodiment, no crack was observed in the battery cell 10 for any weight of the weight. It is considered that the planar gas layer 13 provided between the sealing material 103 and the battery cells 10 suppresses propagation of the shock wave when the module 100 is hit, and prevents the battery cells from being broken by the shock wave.

(modification of embodiment)

In the solar cell module 100 shown in fig. 1, a back contact cell (back contact cell) is used as the cell 10, but the present invention is not limited thereto, and can be applied to a double-sided electrode cell 10a as shown in fig. 7.

As shown in fig. 7, in a module 100A according to the present modification, a front surface electrode (for example, a p-type electrode) of one battery cell 10A and a rear surface electrode (for example, an n-type electrode) of another battery cell 10A adjacent thereto are alternately connected. In the battery cell string 10A configured as described above, the sheet 15 made of transparent resin is provided between the outermost layer, which is the light receiving surface of each battery cell 10A, and the first sealing material 103 a.

When a module is installed on a wall surface of a building, the module lacks variation in appearance, and therefore, the module does not blend with the appearance of the wall surface (for example, the color tone of the wall surface), which may cause deterioration in the appearance of the building. When an incoming object collides with the module, the battery cells in the module may be broken, and the performance of the battery cells may be degraded.

However, as described above, according to the module 100 and the module 100A according to the above embodiments and examples, the gas layer 13 is provided between the sealing material 103 and the light receiving surface of each of the

battery cells

10 and 10A, so that the color tone of the

battery cells

10 and 10A is not impaired, and excellent appearance and beauty can be achieved.

Further, cracks generated in the

battery cells

10 and 10A of the

modules

100 and 100A due to the impact of flying objects can be suppressed, and therefore, the

modules

100 and 100A having excellent reliability can be realized.

Further, since the light receiving surfaces of the

battery cells

10 and 10a are covered with the air layer 13, resistance to a Potential Induced Degradation (PID) phenomenon can be improved. The PID phenomenon is an output drop caused by, for example, sodium (Na) ions or the like diffusing from the

protective materials

105A and 105B into the sealing material 103 at a high voltage and penetrating into the surface or the interior of each

battery cell

10 or 10a when glass is used as the

protective materials

105A and 105B. Therefore, the

modules

100 and 100A suppress the PID phenomenon and exhibit high reliability.

-description of symbols-

100. 100A solar cell module

102 wiring

103 encapsulating material

103a first encapsulating material

103b second encapsulant

105A light-receiving surface protective material (protective member)

105B Back face protective Material (protective Member)

105a black resin layer

105b PET film

10. 10a solar cell (Battery cell)

10A solar cell (cell) string

11 outermost layer (anti-reflection film)

13 gas layer

15 sheets (transparent resin/PET sheet).

Claims

1. A solar cell module, comprising: a plurality of solar cells electrically connected to each other; an encapsulating material encapsulating the plurality of solar cell units; and two protective members that sandwich the sealing material from two main surface sides of the solar battery cells, the two protective members being provided along with the plurality of solar battery cells, the sealing material being provided between the two protective members, the solar battery cell being characterized in that:

each of the solar battery cells is provided with an air layer between at least one of the two main surfaces and the sealing material facing the main surface.

2. The solar cell module of claim 1, wherein:

the gas layer is planar and is provided between the light-receiving-side main surface of each solar battery cell and the sealing material.

3. The solar cell module according to claim 1 or 2, characterized in that:

the gas layer covers at least half of the area of the main surface of each solar cell.

4. The solar cell module according to any one of claims 1 to 3, wherein:

an antireflection film and a transparent resin sheet positioned on the antireflection film are sequentially provided on a light-receiving-side principal surface of each solar cell,

the gas layer is a void layer between the antireflection film and the sheet.

5. The solar cell module of claim 4, wherein:

the surface of the sheet opposite to the antireflection film is roughened.

6. The solar cell module according to any one of claims 1 to 5, wherein:

the air layer is an air layer.

7. The solar cell module according to any one of claims 1 to 6, wherein:

each of the solar cells is a back-contact solar cell.