JP2021093393A - Solar cell module and solar cell module manufacturing method - Google Patents

Abstract

To provide a solar cell module having glare of reflected light reduced.SOLUTION: A solar cell module 1 according to an aspect of the present invention comprises: a plurality of kinds of solar cells 101, 102 and 103. The plurality of kinds of solar cells 101, 102 and 103 have textures 120 that include a plurality of quadrangular pyramid-shaped fine protrusions 121 on each surface, and have semiconductor substrates 110 having a different direction of the fine protrusion 121 for each kind.SELECTED DRAWING: Figure 2

Description

The present invention relates to a solar cell module and a method for manufacturing a solar cell module.

Solar cell modules having a plurality of solar cell cells are used for various purposes. Depending on the location where the solar cell module is installed, the reflection of light on the surface of the solar cell may become a problem. The solar cell is often provided with an antireflection film, but the reflection of light cannot be prevented depending on the incident angle of light. Such reflection of light may be dazzling to the people around it and may be aesthetically unpleasant.

As a technique for improving the aesthetic appearance of a solar cell module, Patent Document 1 states that in a solar cell module, silicon wafers (solar cell cells) are arranged so that the uneven direction of slice marks on the surface thereof has a specific pattern. Are listed. In the solar cell module described in Patent Document 1, it is considered that the glare is reduced because the reflection of light is dispersed by the unevenness of the slice marks. However, in a solar cell using a silicon wafer whose surface smoothness has been improved by polishing or the like in order to improve the photoelectric conversion efficiency, slice marks cannot be confirmed and it has almost no effect on light reflection. A sufficient effect cannot be obtained with the configuration described in Patent Document 1.

Japanese Unexamined Patent Publication No. 2013-89624

An object of the present invention is to provide a solar cell module in which the glare of reflected light is reduced and a method for manufacturing the solar cell module.

The solar cell module according to one aspect of the present invention includes a plurality of types of solar cells, and the plurality of types of solar cells each have a texture including a plurality of quadrangular pyramid-shaped fine protrusions formed on the surface thereof. Each has a semiconductor substrate in which the orientation of the fine protrusions is different.

In the solar cell module, the difference in the orientation of the fine protrusions may include the difference in the inclination angle of the central axis of the fine protrusions with respect to the normal direction of the semiconductor substrate.

In the solar cell module, the difference in the orientation of the fine protrusions may include the difference in the orientation angle about the central axis of the fine protrusions.

The method for manufacturing a solar cell module according to one aspect of the present invention includes a step of forming a plurality of types of solar cells and a step of forming a solar cell module using the plurality of types of solar cells. The step of forming a type of solar cell includes a step of etching the surface of a semiconductor substrate having a different crystal orientation for each type.

In the method for manufacturing a solar cell module, wafers obtained by slicing an ingot at different angles may be used as the semiconductor substrate having different crystal orientations.

In the method for manufacturing a solar cell module, wafers having different orientation directions in a plane may be used.

According to the present invention, it is possible to provide a solar cell module in which the glare of reflected light is reduced.

It is a schematic plan view which shows the solar cell module of 1st Embodiment of this invention. It is a schematic sectional view of the solar cell module of FIG. It is a flowchart which shows the procedure of the manufacturing method of the solar cell module of FIG. It is a schematic cross-sectional view which shows the solar cell module of the 2nd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience, hatching, member codes, etc. may be omitted, but in such cases, other drawings shall be referred to. Further, the dimensions of the various members in the drawings are adjusted for convenience so that they can be easily seen.

<First Embodiment>
1 and 2 show the solar cell module 1 according to the first embodiment of the present invention. FIG. 1 is a schematic plan view of the solar cell module 1, and FIG. 2 is a schematic cross-sectional view of the solar cell module 1.

The solar cell module 1 includes a plurality of solar cell strings 10, a front side protective member 20 arranged on the front surface (incident surface) side of the solar cell string 10, and a back side protective member 30 arranged on the back surface side of the solar cell string 10. A sealing material 40 filled in the gap between the front side protective member 20 and the back side protective member 30, and a connecting member 50 for connecting between the solar cell strings.

The solar cell string 10 is formed by connecting a plurality of types of solar cell cells 101, 102, 103, respectively. Therefore, the solar cell module 1 includes a plurality of types of solar cell cells 101, 102, 103. As shown in the figure, the solar cell string 10 can have an interconnector 200 for connecting a plurality of solar cells 101, 102, 103. Further, the solar cell string 10 and the solar cell cells 101, 102, 103 may be directly connected by overlapping the ends thereof.

In the solar cell string 10, it is preferable that a plurality of types of solar cells 101, 102, 103 are arranged so that the same types of solar cells 101, 102, 103 are not continuous. The solar cells 101, 102, and 103 have different light reflection characteristics depending on the type, as will be described in detail later. Therefore, since the solar cells 101, 102, and 103 of the same type are not continuous, the area of the region that reflects light in the same direction in the solar cell string 10 is reduced, so that the glare of the reflected light can be reduced. it can. Further, in the solar cell module 1, it is preferable that the solar cells 101, 102, 103 of the same type are not continuous even between adjacent solar cell strings 10. The ratio and arrangement order of the solar cells 101, 102, and 103 of each type are not particularly limited, and can be appropriately combined in consideration of design and the like.

Each of the solar cells 101, 102, and 103 has a semiconductor substrate 110. The semiconductor substrate 110 may be formed by laminating a thin film of amorphous silicon having an appropriate conductive type so as to form a pn junction for performing photoelectric conversion on the surface of a base material layer formed of single crystal silicon. .. Further, the semiconductor substrate 110 may further have an antireflection film or the like. Further, electrodes for extracting electric power are laminated on the main surface of the semiconductor substrate 110.

A texture 120 including a plurality of quadrangular pyramid-shaped fine protrusions 121 is formed on the surface (light incident surface) of the semiconductor substrate 110. The texture 120 preferably includes a large number of fine protrusions 121 formed without interruption so as to cover the surface of the semiconductor substrate 110. The plurality of microprojections formed in the same solar cell 101, 102, 103 are all oriented in the same direction. However, the orientation of the microprojections 121 differs depending on the type of solar cell 101, 102, 103.

In the solar cell string 10, the difference in the orientation of the microprojections 121 between the types of the solar cells 101, 102, 103 is that the central axis of the microprojections 121 with respect to the normal direction of the semiconductor substrate 110 (passing through the apex and having the smallest area). It is the difference in the inclination angle of the straight line connecting the centers of gravity of the cross section. At the bottom of FIG. 1, one microprojection of each type of solar cell 101, 102, 103 is enlarged and shown. Specifically, the central axis of the microprojections 121 in the first type of solar cell 101 is inclined by a first angle in the first direction with respect to the normal direction of the semiconductor substrate 110. The central axis of the microprojections 121 in the second type of solar cell 102 is parallel to the normal direction of the semiconductor substrate 110 in the first direction. The central axis of the microprojections 121 in the third type of solar cell 103 is inclined by a first angle in a direction opposite to the first direction with respect to the normal direction of the semiconductor substrate 110.

Since the inclination of the central axis of the microprojection 121 is different, the direction of light reflected by the solar cells 101, 102, and 103 may be different from the direction of light incident on the solar cell module 1. Specifically, as illustrated by the alternate long and short dash line in FIG. 2, the light reflected by the solar cells 101, 102, and 103 is reflected only once or twice depending on the incident direction of the light. It may become. More specifically, when the incident angle of the light with respect to the solar cells 101, 102, 103 is not so large, the light is reflected twice, and the inclination angle of the microprojection 121 in the incident direction of the light with respect to the central axis is equal to or more than a certain value. In some cases, it is a one-time reflection. The solar cells 101, 102, 103 absorb a part of the incident light inside and reflect the rest on the surface of the fine protrusion 121. Therefore, when the light is reflected only once, the solar cells 101, 102 , 103 has a relatively high reflectance.

Since the solar cell module 1 has a plurality of types of solar cell cells 101, 102, 103 having different inclinations of the central axes of the microprojections 121, light can be emitted even when the incident angle of light on the solar cell module 1 is large. It has a solar cell 101 that emits light from the solar cell module 1 with only one reflection, and solar cells 102 and 103 that emit light from the solar cell module 1 with two reflections. Therefore, the glare of the solar cell module 1 is reduced by preventing the entire solar cell module 1 from appearing to shine due to the reflected light. Further, in the solar cell module 1 having a plurality of types of solar cells 101, 102, 103 having different light reflection characteristics, the light absorption rate does not significantly decrease even if the incident angle of light increases. The decrease in conversion efficiency is relatively small.

The fine protrusions 121 can be formed by performing anisotropic crystal etching on a single crystal silicon substrate that is a base material of the semiconductor substrate 110. Since the silicon crystal has a crystal face that is difficult to be etched, it is possible to form a texture 120 in which only the surface that is difficult to be etched is exposed on the surface by etching under appropriate conditions. The hard-to-etch surfaces of crystalline silicon form the four sides of the quadrangular pyramid-shaped microprojections 121.

As the single crystal silicon substrate, a substrate having a (001) plane as a surface is generally used. The fine protrusions 121 formed by etching a single crystal silicon substrate having a (001) plane as a surface are inclined by 55 degrees with respect to the surface of the semiconductor substrate 110, and the inclination directions are different by 90 degrees from each other. It becomes a quadrangular pyramid like a pyramid formed from a plane. Further, if a single crystal silicon substrate having a surface inclined with respect to the (001) surface, that is, a silicon wafer manufactured by slicing an ingot in the inclined direction is etched, the inclination angle of the main surface with respect to the (001) surface is obtained. It is possible to form the fine protrusion 121 whose central axis is inclined.

Therefore, the first type of solar cell 101 is formed by using a silicon wafer sliced so that its surface is inclined by a first angle in the first direction with respect to the (001) surface. The second type of solar cell 102 can be formed by using a silicon wafer having a (001) surface as a surface, and the third type of solar cell 103 has a surface thereof. It can be formed by using a silicon wafer sliced so as to be a surface inclined by a first angle in a direction opposite to the first direction with respect to the (001) surface.

The inclination angle of the central axis of the fine protrusions 121 with respect to the normal direction of the semiconductor substrate 110 in the solar cells 101, 102, 103 is preferably 40 degrees or less, more preferably 20 degrees or less. By selecting the inclination angle of the central axis of the fine protrusions 121 within the range of the upper limit or less, the light absorption rate of the semiconductor substrate 110 can be relatively increased, so that the photoelectric conversion efficiency can be increased. ..

The arithmetic surface roughness of the texture 120 is preferably 0.1 μm or more and 10.0 μm or less, and more preferably 1.0 μm or more and 3.0 μm or less. By setting the arithmetic surface roughness of the texture 120 within the above range, the light absorption rate can be improved and the open circuit voltage can be increased.

The front side protective member 20 protects the solar cell 1 by covering the surface of the solar cell string 10, that is, the solar cell 1 via the sealing material 40. The front side protective member 20 can be formed of a plate-shaped or sheet-shaped material, and is preferably excellent in translucency and weather resistance. Specifically, as the material of the front side protective member 20, for example, a transparent resin such as an acrylic resin or a polycarbonate resin, glass, or the like can be mentioned. Further, the surface of the front side protective member 20 may be processed into an uneven shape or coated with an antireflection coating layer in order to suppress the reflection of light.

The back side protective member 30 covers the back surface of the solar cell string 10 via the sealing material 40 to protect the solar cell 11. Like the front side protective member 20, the back side protective member 30 can be formed from a plate-shaped or sheet-shaped material, and is preferably excellent in water shielding. Specifically, the back side protective member 30 is a laminate of, for example, a resin film such as polyethylene terephthalate (PET), polyethylene (PE), an olefin resin, a fluorine-containing resin, or a silicone resin, and a metal foil such as aluminum foil. Is preferably used.

The sealing material 40 seals and protects the solar cell string 10, that is, the solar cell 11, and is between the light receiving side surface and the front side protective member 20 of the solar cell 11 and the solar cell 11. It is interposed between the back side surface of the and the back side protective member 30.

The sealing material 40 protects the solar cell 11 by adhering the solar cell string 10, the front side protective member 20 and the back side protective member 30, and eliminating the gap around the solar cell string 10. Therefore, examples of the sealing material 40 include ethylene / vinyl acetate copolymer (EVA), ethylene / α-olefin copolymer, ethylene / vinyl acetate / triallyl isocyanurate (EVAT), and polyvinyl butyral (PVB). ), Acrylic resin, urethane resin, or a translucent thermoplastic resin such as silicone resin is preferably used.

The connecting member 50 connects between the solar cells 11 at one end of the solar cell string 10 and between the solar cells 11 at the other end of the solar cell string 10, respectively. The connection member 50 extends outward from between the front side protection member 20 and the back side protection member 30 so as to be connectable to the circuit outside the solar cell module 1.

As described above, the solar cell module 1 having the above configuration can prevent the light reflectance from becoming high on the entire surface, so that the glare of the reflected light is reduced.

(Solar cell module manufacturing method)
The solar cell module 1 can be manufactured by the embodiment of the solar cell module manufacturing method according to the present invention shown in FIG.

The solar cell module manufacturing method of FIG. 2 includes a step of forming a plurality of types of solar cell cells 101, 102, 103 (step S10: cell forming step) and a solar cell using a plurality of types of solar cell cells 101, 102, 103. A step of forming the battery module 1 (step S20: module forming step) is provided.

The cell forming step of step S10 includes a step of etching the surface of the semiconductor substrate 110 having different crystal orientations for each type of solar cell 101, 102, 103 to be obtained (step S11: etching step) and a step of etching the semiconductor substrate 110. It includes a step of forming a pn junction for performing photoelectric conversion (step S12: a pn junction forming step) and a step of forming an electrode for extracting electric power on the semiconductor substrate 110 (step S13: an electrode forming step).

In the etching step of step S11, a texture 120 including a plurality of fine protrusions 121 is formed on the surface of the semiconductor substrate 110 by etching under conditions that do not erode the crystal plane of the semiconductor substrate 110 that is difficult to be etched.

In the etching step, a silicon wafer formed by slicing an ingot at different angles can be used as the semiconductor substrate 110 having different crystal orientations. That is, the inclination angle of the formed fine protrusions 121 with respect to the normal of the semiconductor substrate 110 can be selected depending on the angle at which the ingot is sliced.

In the pn junction forming step of step S12, a pn junction for performing photoelectric conversion is formed by diffusing a dopant on the surface of the semiconductor substrate 110 or laminating a semiconductor material having a desired conductive type on the surface of the semiconductor substrate 110. Form.

In the electrode forming step of step S13, an electrode having a desired pattern is formed by printing and firing a conductive paste, forming a metal layer for forming a resist pattern, and the like. Further, a multi-layer electrode structure may be formed in which a current collecting member such as a bus bar is further connected to the electrode pattern laminated on the semiconductor substrate 110.

In the module forming step of step S20, the space between the step of forming the solar cell string 10 (step S21: string forming step) and the front side protective member 20, the solar cell string 10 and the back side protective member 30 is sealed by the sealing material 40. (Step S22: sealing step) and the like.

In the string forming step of step S21, the solar cell string 10 is formed by connecting a plurality of types of solar cells 101, 102, 103 side by side.

In the sealing step of step S22, the front side protective member 20, the material forming the front surface side portion of the sealing material 40, the plurality of solar cell strings 10 and the connecting member 50 arranged side by side, and the back surface side portion of the sealing material 40 are separated. The material to be formed and the back side protective member 30 are laminated, and the material forming the sealing material 40 is melted by a hot press to seal the plurality of solar cell strings 10. The plurality of solar cell strings 10 and the connecting member 50 may be connected by a hot press, or may be connected in advance.

<Second Embodiment>
Subsequently, FIG. 4 shows the solar cell module 1A according to the second embodiment of the present invention. Regarding the solar cell module 1A of FIG. 4, the same components as those of the solar cell module of FIG. 1 are designated by the same reference numerals, and redundant description and illustration may be omitted.

The solar cell module 1A includes a plurality of solar cell strings 10A, a front side protective member 20 arranged on the front surface side of the solar cell string 10A, a back side protection member 30 arranged on the back surface side of the solar cell string 10A, and front side protection. It includes a sealing material 40 that fills the gap between the member 20 and the back side protective member 30, and a connecting member 50 that connects the solar cell strings.

The solar cell string 10A is formed by connecting a plurality of types of solar cell cells 101A, 102A, 103A, respectively. The solar cells 101A, 102A, and 103A each have a semiconductor substrate 110. A texture 120 including a plurality of quadrangular pyramid-shaped fine protrusions 121 is formed on the surface of the semiconductor substrate 110. The orientation of the microprojections 121 differs depending on the type of solar cell 101A, 102A, 103A.

In the solar cell string 10A, the difference in the orientation of the fine protrusions 121 among the types of the solar cells 101A, 102A, 103A is the orientation angle which is the rotation position about the central axis of the fine protrusions 121. Specifically, one side of the bottom surface of the microprojection 121 in the first type of solar cell 101 is parallel to the extending direction of the solar cell string 10A, that is, the connecting direction of the solar cells 101A, 102A, 103A. The microprojection 121 in the second type solar cell 102 has one side of the bottom surface inclined by 30 degrees with respect to the extending direction of the solar cell string 10A, and the microprojection 121 in the third type solar cell 103. Is inclined by 60 degrees with respect to the extending direction of the solar cell string 10A on one side of the bottom surface.

Due to the different orientation directions of the microprojections 121, as illustrated by the alternate long and short dash line in FIG. 4, the light reflection directions of the solar cells 101A, 102A, and 103A are different from the light incident directions on the solar cell module 1A. Can be different. As a result, the area of the region of the solar cell string 10 that reflects light in the same direction becomes smaller, so that the glare of the reflected light can be reduced.

The solar cells 101A, 102A, and 103A having different orientation directions of the fine protrusions 121 are semiconductors in a step of forming a pn junction for performing photoelectric conversion on the semiconductor substrate 110 and a step of forming an electrode for extracting electric power on the semiconductor substrate 110. It can be formed by making the orientation direction of the substrate 110 different in the plane. That is, different types of solar cells 101A, 102A, and 103A can be formed by different orientation directions of silicon wafers used in the same process, that is, different notch arrangements. It should be noted that the "same process" does not require that various conditions be exactly the same, and it is possible to change the order or replace with an equivalent process based on common general technical knowledge.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and modifications can be made.

As an example, in the solar cell module according to the present invention, the number of types of solar cells may be 2 or more, and may be 4 or more. Further, in the solar cell module according to the present invention, the solar cell may have a configuration other than the orientation of the fine protrusions replaced with a functionally equivalent configuration for each type based on common general technical knowledge.

Further, in the solar cell module according to the present invention, the difference in the orientation of the fine protrusions is the difference in the inclination angle of the central axis of the fine protrusions with respect to the normal direction of the semiconductor substrate and the difference in the orientation angle about the central axis of the fine protrusions. May include both. As a result, even if the number of types of solar cells is increased, the difference in the light reflection characteristics between the solar cells can be increased, so that the glare of the reflected light of the solar cell module can be reduced more reliably. Can be done. Solar cells having different inclination angles and orientation directions of the central axes of the fine protrusions can be obtained by subjecting wafers obtained by slicing ingots at different angles to the same process with different orientation directions in a plane.

Further, the solar cell module according to the present invention is not limited to the one manufactured by the solar cell module manufacturing method according to the present invention.

1,1A Solar cell module 10,10A Solar cell string 20 Front side protective member 30 Back side protective member 40 Encapsulant 50 Connector member 101, 101A, 102, 102A, 103, 103A Solar cell 110 Semiconductor substrate 120 Texture 121 Fine protrusion 200 Interconnector

Claims (6)

Equipped with multiple types of solar cells
The plurality of types of solar cells are solar cell modules each having a texture including a plurality of quadrangular pyramid-shaped fine protrusions on the surface thereof, and having a semiconductor substrate in which the directions of the fine protrusions are different for each type. The solar cell module according to claim 1, wherein the difference in the orientation of the fine protrusions includes a difference in the inclination angle of the central axis of the fine protrusions with respect to the normal direction of the semiconductor substrate. The solar cell module according to claim 1 or 2, wherein the difference in the orientation of the fine protrusions includes a difference in the orientation angle about the central axis of the fine protrusions. The process of forming multiple types of solar cells and
A step of forming a solar cell module using the plurality of types of solar cells, and
With
The step of forming the plurality of types of solar cells is a method for manufacturing a solar cell module, which includes a step of etching the surface of a semiconductor substrate having a different crystal orientation for each type. The method for manufacturing a solar cell module according to claim 4, wherein wafers obtained by slicing ingots at different angles are used as the semiconductor substrates having different crystal orientations. The method for manufacturing a solar cell module according to claim 4 or 5, wherein wafers having different orientation directions in a plane are used as the semiconductor substrates having different crystal orientations.

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