KR20180071857A - Back sheet and solar cell panel including the same - Google Patents

Abstract

According to an embodiment of the present invention, a solar cell panel includes: a solar cell having a double-sided light receiving structure; a front substrate disposed on the front surface of the solar cell and having a light transmitting property; a back sheet disposed on the back surface of the solar cell and having a light transmitting property; and a sealing material surrounding the solar cell and positioned between the front substrate and the back sheet. The back sheet includes a transparent moisture-proof film constituting an outer surface and composed of a compound containing aluminum and oxygen.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a back sheet,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a back sheet and a solar cell panel including the same, and more particularly, to a back sheet having improved structure and a solar cell panel including the same.

With the recent depletion of existing energy sources such as oil and coal, interest in alternative energy to replace them is increasing. Among them, solar cells are attracting attention as a next-generation battery that converts solar energy into electric energy.

Since the solar cell must be exposed to the external environment for a long time, it is manufactured in a panel form by a packaging process for protecting the solar cell. Since the solar cell panel manufactured in this way must be developed in various environments, it must have high long-term reliability so that it can be generated for a long time in various environments.

On the other hand, there is a growing interest in solar cell panels that can use both light incident on both sides to improve output. In this case, transparent glass substrates may be used for the front and rear surfaces, respectively, so that light can be incident on both surfaces. However, the glass substrate is heavy and is not easy to handle, and bubbles may be generated when the solar cell panel is bonded to other materials constituting the solar panel. When a sheet or film is used instead of the glass substrate on the back surface to prevent this, the moisture permeability of the sheet, film, or the like is high, so that the moisture resistance is low and the hardness is low.

SUMMARY OF THE INVENTION The present invention is to provide a back sheet having translucency, excellent moisture-proofness and high abrasion resistance, and a solar cell panel comprising the same.

A solar cell panel according to an embodiment of the present invention includes a solar cell having a double-side light-receiving structure; A front substrate disposed on a front surface of the solar cell and having a light transmitting property; A back sheet disposed on a rear surface of the solar cell and having a light transmitting property; And a sealing material surrounding the solar cell and positioned between the front substrate and the rear sheet. The back sheet includes a transparent moisture-proof film constituting an outer surface and composed of a compound containing aluminum and oxygen.

According to this embodiment, the back sheet has a transparent moisture-proofing film composed of a compound containing aluminum and oxygen on its outer surface, and can have excellent light-transmitting property, moisture-proof property and abrasion resistance. Accordingly, the present invention can be applied to a solar cell panel having a double-side light-receiving structure, and can have excellent moisture-proof property and wear resistance without interfering with light incident on the rear surface. As a result, it is possible to prevent the problem of using a glass substrate on the rear surface and to exhibit excellent moisture-proof and abrasion resistance as a glass substrate.

1 is an exploded perspective view schematically illustrating a solar cell panel according to an embodiment of the present invention.
2 is a sectional view cut along the line II-II in Fig.
3 is a cross-sectional view illustrating a solar cell according to an embodiment of the present invention.
4 is a front plan view of the solar cell shown in FIG.
5 is a partially enlarged cross-sectional view of a solar cell panel according to another embodiment of the present invention.
6 is a partially enlarged cross-sectional view of a solar cell panel according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it is needless to say that the present invention is not limited to these embodiments and can be modified into various forms.

In the drawings, the same reference numerals are used for the same or similar parts throughout the specification. In the drawings, the thickness, the width, and the like are enlarged or reduced in order to make the description more clear, and the thickness, width, etc. of the present invention are not limited to those shown in the drawings.

Wherever certain parts of the specification are referred to as "comprising ", the description does not exclude other parts and may include other parts, unless specifically stated otherwise. Also, when a portion of a layer, film, region, plate, or the like is referred to as being "on" another portion, it also includes the case where another portion is located in the middle as well as the other portion. When a portion of a layer, film, region, plate, or the like is referred to as being "directly on" another portion, it means that no other portion is located in the middle.

Hereinafter, a back sheet according to an embodiment of the present invention and a solar cell panel including the same will be described in detail with reference to the accompanying drawings.

FIG. 1 is an exploded perspective view schematically showing a solar cell panel according to an embodiment of the present invention, and FIG. 2 is a sectional view cut along a line II-II in FIG.

1 and 2, a solar cell panel 100 according to the present embodiment includes a solar cell 150 having a bi-facial structure, a solar cell 150 disposed on a front surface of the solar cell 150, A back sheet 120 having a light transmitting property and positioned on the rear surface of the solar cell 150 and a rear surface sheet 120 surrounding the solar cell 150 while being sandwiched between the front substrate 110 and the back sheet 120 As shown in FIG. In the present embodiment, the back sheet 120 includes a transparent moisture-proof film 120b constituting an outer surface and composed of a compound containing aluminum and oxygen. This will be explained in more detail.

First, the solar cell 150 may include a photoelectric conversion unit that converts the solar cell into electric energy, and an electrode that is electrically connected to the photoelectric conversion unit and collects and transfers a current. In this embodiment, a photoelectric conversion portion including a semiconductor substrate (for example, a silicon wafer) and a conductive type region can be applied as an example. At this time, the solar cell 150 may have a double-sided light receiving type structure in which light can be received on both sides of the semiconductor substrate. An example of the solar cell 150 having such a double-side light-receiving structure will be described in detail with reference to FIGS. 3 and 4. Next, the solar cell panel 100 will be described in detail with reference to FIG. 1 and FIG.

FIG. 3 is a cross-sectional view illustrating a solar cell 150 according to an embodiment of the present invention, and FIG. 4 is a front plan view of the solar cell 150 shown in FIG.

In this embodiment, the solar cell 150 includes a semiconductor substrate 152 including a base region 10, conductive regions 20 and 30 formed on the semiconductor substrate 152 or on the semiconductor substrate 152, And electrodes 42 and 44 connected to the conductive regions 20 and 30, respectively. The conductive regions 20 and 30 may include a first conductive type region 20 and a second conductive type region 30 having different conductivity types and the electrodes 42 and 44 may include a first conductive type Type region 20 and a second electrode 44 connected to the second conductivity type region 30. The first electrode 42 and the second electrode 44 may be connected to each other. This will be explained in more detail.

The semiconductor substrate 152 may include a base region 10 having a first or second conductivity type including a first or second conductivity type dopant at a relatively low doping concentration. In one example, the base region 10 may have a second conductivity type. The base region 10 may be comprised of a single crystalline semiconductor (e.g., a single single crystal or polycrystalline semiconductor, such as single crystal or polycrystalline silicon, particularly monocrystalline silicon) comprising a first or second conductivity type dopant. The solar cell 150 based on the base region 10 or the semiconductor substrate 152 having a high degree of crystallinity and having few defects is excellent in electrical characteristics.

An anti-reflection structure capable of minimizing reflection can be formed on the front and rear surfaces of the semiconductor substrate 152. For example, a texturing structure having a concavo-convex shape in the form of a pyramid or the like may be provided as an antireflection structure. The texturing structure formed in the semiconductor substrate 152 may have a certain shape (e.g., a pyramid shape) having an outer surface formed along a specific crystal plane (e.g., (111) plane) of the semiconductor. If the surface roughness of the semiconductor substrate 152 is increased due to such texturing, the reflectance of the light incident on the semiconductor substrate 152 may be reduced to minimize the loss of light. However, the present invention is not limited thereto, and a texturing structure may be formed on only one side of the semiconductor substrate 152, or a texturing structure may not be formed on the front and back sides of the semiconductor substrate 152.

A first conductive type region 20 having a first conductive type may be formed on one side (for example, a front side) of the semiconductor substrate 152. A second conductivity type region 30 having a second conductivity type may be formed on the rear surface of the semiconductor substrate 152. The first and second conductivity type regions 20 and 30 may have a different conductivity type from the base region 10 or may have a doping concentration higher than that of the base region 10, .

In this embodiment, the first and second conductivity type regions 20 and 30 may be configured as a doped region constituting a part of the semiconductor substrate 152. The first conductive type region 20 may be composed of a crystalline semiconductor (e.g., a single crystal or polycrystalline semiconductor, for example, single crystal or polycrystalline silicon, particularly monocrystalline silicon) including a first conductive type dopant. And the second conductivity type region 30 may be composed of a crystalline semiconductor (e.g., a single crystal or a polycrystalline semiconductor, for example, a single crystal or a polycrystalline silicon, particularly, a single crystal silicon) including a second conductive type dopant. As described above, when the first and second conductivity type regions 20 and 30 constitute a part of the semiconductor substrate 152, the junction characteristics with the base region 10 can be improved.

At this time, in the drawing, the first conductive type region 20 is formed as a whole and has a homogeneous structure having a uniform doping concentration, and the second conductive type region 30 has a uniform structure. Thus, the area of the first and second conductivity type regions 20 and 30 can be sufficiently secured, and the first and second conductivity type regions 20 and 30 can be formed by a simple process. However, the present invention is not limited thereto. Thus, the first conductive type region 20 can be a uniform structure or a selective structure, and the second conductive type region 30 can have a uniform structure, an optional structure, or a local structure have. The selective structure has a high doping concentration, a large junction depth, and a low resistance in a portion adjacent to the first or second electrode 42 or 44 in the first or second conductivity type region 20 or 30, Doping concentration, small junction depth, and high resistance. In the selective structure, the contact resistance with the first or second electrode 42, 44 can be reduced, and the recombination characteristic can be improved. In the local structure, the second conductive type region 30 is formed locally at a portion adjacent to the second electrode 44. [ In the local structure, the short-circuit current (Jsc) and the open-circuit voltage can be improved by minimizing the area of the second conductivity type region 30 to reduce recombination. Various other structures can be applied.

Alternatively, at least one of the first and second conductivity type regions 20 and 30 may be formed separately from the semiconductor substrate 152 above the semiconductor substrate 152. In this case, a semiconductor layer (for example, an amorphous semiconductor layer, an amorphous semiconductor layer, or the like) having a crystal structure different from that of the semiconductor substrate 152 is formed so that the first or second conductivity type regions 20 and 30 can be easily formed on the semiconductor substrate 152, A microcrystalline semiconductor layer, or a polycrystalline semiconductor layer, for example, an amorphous silicon layer, a microcrystalline silicon layer, or a polycrystalline silicon layer). At this time, a separate layer (a tunneling layer, a passivation layer, etc.) may be formed between the first and second conductive regions 20 and 30 and the semiconductor substrate 152.

One of the first and second conductivity type regions 20 and 30 having a conductivity type different from that of the base region 10 constitutes at least a part of the emitter region. The emitter region forms a pn junction with the base region 10 to produce a carrier by photoelectric conversion. The other of the first and second conductivity type regions 20 and 30 having the same conductivity type as the base region 10 constitutes at least a part of a surface field region. The electric field region forms an electric field that prevents carriers from being lost by recombination on the surface of the semiconductor substrate 152. [ For example, in this embodiment, the base region 10 has a second conductivity type, the first conductivity type region 20 constitutes an emitter region, and the second conductivity type region 30 constitutes a rear electric field region can do. However, the present invention is not limited thereto.

In the present embodiment, various materials which can represent n-type or p-type can be used as the first or second conductivity type dopant. As the p-type dopant, a group III element such as boron (B), aluminum (Al), gallium (Ga), or indium (In) can be used. In the case of the n-type, Group 5 elements such as phosphorus (P), arsenic (As), bismuth (Bi) and antimony (Sb) can be used. For example, the p-type dopant may be boron (B) and the n-type dopant may be phosphorus (P).

For example, in this embodiment, the base region 10 and the second conductivity type region 30 may have an n-type and the first conductivity type region 20 may have a p-type. Then, the base region 10 and the first conductive type region 20 form a pn junction. When the pn junction is irradiated with light, electrons generated by the photoelectric effect move toward the rear surface of the semiconductor substrate 152, are collected by the second electrode 44, and the holes move toward the front surface of the semiconductor substrate 152, 1 electrode 42. In this case, Thereby, electric energy is generated. Then, holes having a slower moving speed than electrons may move to the front surface of the semiconductor substrate 152, thereby improving the efficiency. However, the present invention is not limited thereto, and it is also possible that the base region 10 and the second conductivity type region 30 have a p-type and the first conductivity type region 20 has an n-type.

The first passivation film 22 and / or the second passivation film 22 are formed on at least the front surface of the semiconductor substrate 152 (more precisely, on the first conductive type region 20 formed on the front surface of the semiconductor substrate 152) Barrier film 24 may be located. And a second passivation film 32 as a second insulating film may be located at least on the rear surface of the semiconductor substrate 152 (more precisely on the second conductive type region 30 formed on the rear surface of the semiconductor substrate 152) have. The first passivation film 22 and the second passivation film 32 may be formed in contact with the semiconductor substrate 152 and / or the antireflection film 24 may be formed in contact with the first passivation film 22 . Then, the structure can be simplified. However, the present invention is not limited thereto.

The first passivation film 22 and the antireflection film 24 may be formed entirely on the front surface of the semiconductor substrate 152 substantially except for the first opening 102. [ The second passivation film 32 may be formed entirely on the rear surface of the semiconductor substrate 152 except for the second opening 104.

The first passivation film 22 or the second passivation film 32 is formed in contact with the semiconductor substrate 152 to passivate defects present in the front surface or bulk of the semiconductor substrate 152. Accordingly, it is possible to increase the open-circuit voltage of the solar cell 150 by removing recombination sites of the minority carriers. The antireflection film 24 reduces the reflectance of light incident on the front surface of the semiconductor substrate 152, thereby increasing the amount of light reaching the pn junction. Accordingly, the short circuit current Isc of the solar cell 150 can be increased.

The first passivation film 22, the antireflection film 24, and the second passivation film 32 may be formed of various materials. In one example, the first passivation film 22, the anti-reflection film 24 or the passivation film 32 is a silicon nitride film, a silicon nitride film containing hydrogen, silicon oxide, silicon nitride oxide, aluminum oxide film, a silicon carbide film, MgF _2, ZnS , TiO _2, and CeO ₂ , or a multi-layer structure in which two or more films are combined.

For example, in the present embodiment, the first passivation film 22 and / or the antireflection film 24 and the second passivation film 32 may not have a dopant or the like so as to have excellent insulating properties, passivation properties, and the like . However, the present invention is not limited thereto.

The first electrode 42 is formed by filling at least a portion of the first opening 102 and is electrically connected to the first conductive region 20 2 opening portion 104 and is electrically connected to (e.g., formed in contact with) the second conductive type region 30. [0050] The first and second electrodes 42 and 44 are made of various conductive materials (for example, metal) and may have various shapes.

Referring to FIG. 4, the first electrode 42 may include a plurality of finger electrodes 42a spaced apart from each other with a predetermined pitch. Although the finger electrodes 42a are parallel to each other and parallel to the edge of the semiconductor substrate 152, the present invention is not limited thereto. The first electrode 42 may include a bus bar electrode 42b formed in a direction crossing (for example, orthogonal to) the finger electrodes 42a and connecting the finger electrodes 42a. Only one bus bar electrode 42b may be provided or a plurality of bus bar electrodes 42b may be provided with a larger pitch than the pitch of the finger electrodes 42a as shown in FIG. At this time, the width of the bus bar electrode 42b may be larger than the width of the finger electrode 42a, but the present invention is not limited thereto. Therefore, the width of the bus bar electrode 42b may be equal to or smaller than the width of the finger electrode 42a.

The finger electrode 42a and the bus bar electrode 42b of the first electrode 42 may both be formed through the first passivation film 22 and the antireflection film 24 which are the first insulating film . That is, the first opening 102 may be formed corresponding to both the finger electrode 42a and the bus bar electrode 42b of the first electrode 42. [ However, the present invention is not limited thereto. As another example, the finger electrode 42a of the first electrode 42 may be formed through the first insulating film, and the bus bar electrode 42b may be formed on the first insulating film. In this case, the first opening 102 is formed in a shape corresponding to the finger electrode 42a, and may not be formed in a portion where only the bus bar electrode 42b is located.

The second electrode 44 may include a finger electrode and a bus bar electrode corresponding to the finger electrode 42a and the bus bar electrode 42b of the first electrode 42, respectively. The finger electrode 42a and the bus bar electrode 42b of the first electrode 42 may be directly applied to the finger electrode and the bus bar electrode of the second electrode 44. [ At this time, the content of the first passivation film 22 and the antireflection film 24 which are the first insulating film in the first electrode 42 is transferred from the second electrode 44 to the second passivation film 34 which is the second insulating film Can be applied. The width and pitch of the finger electrode 42a and the bus bar electrode 42b of the first electrode 42 may be the same as the width and pitch of the finger electrode and the bus bar electrode of the second electrode 44, .

However, the present invention is not limited thereto, and the first electrode 42 and the second electrode 44 may have different planar shapes, and various other modifications are possible.

As described above, in this embodiment, the first and second electrodes 42 and 44 of the solar cell 150 have a certain pattern, so that the solar cell 150 can be incident on the front and rear surfaces of the semiconductor substrate 152 It has a double-sided light-receiving structure. Accordingly, the amount of light used in the solar cell 150 can be increased to contribute to the efficiency improvement of the solar cell 150.

In the above description, an example of the solar cell 150 has been described with reference to Figs. 3 and 4. Fig. However, the present invention is not limited thereto, and the structure, mode, etc. of the solar cell 150 may be variously modified. For example, the solar cell 150 may be a photoelectric conversion unit having various structures such as using a compound semiconductor or using a dye sensitized material.

Referring again to FIGS. 1 and 2, a plurality of solar cells 150 are provided in this embodiment, and a plurality of solar cells 150 are electrically connected in series, parallel, or series-parallel by an interconnector 142 . Various shapes and shapes for connecting the solar cell 150 such as a ribbon and a wire can be applied to the inductor connector 142. The present invention is not limited to the number of the interconnectors 142 used in each solar cell 150, Do not.

3 and 4) formed on the front surface of the solar cell 150 and a second electrode (not shown in FIG. 3 and FIG. 4, hereinafter the same) formed on the rear surface of another adjacent solar cell 150. Specifically, Electrodes (44 in Fig. 3 and Fig. 4, the same applies hereinafter) can be connected by a tabbing process. In the tableting process, the interconnector 142 may be attached to the electrodes 42 and 44 of the solar cell 150 using a solder material.

Alternatively, a conductive film (not shown) may be attached between the solar cell 150 and the interconnector 142, and then the plurality of solar cells 150 may be connected in series or in parallel by thermocompression bonding. The conductive film (not shown) may be formed by dispersing electrically conductive particles formed of gold, silver, nickel, copper or the like having excellent conductivity in a film formed of an epoxy resin, an acrylic resin, a polyimide resin, a polycarbonate resin or the like. When the conductive film is compressed while being heated, the conductive particles are exposed to the outside of the film, and the solar cell 150 and the interconnector 142 can be electrically connected by the exposed conductive particles. When a plurality of solar cells 150 are modularized by the conductive film (not shown), the process temperature can be lowered, and warpage of the solar cell 150 can be prevented.

The bus ribbon 145 alternately connects both ends of the interconnect 142 of one row of solar cells 150 (i.e., solar cell strings) connected by the interconnect 142. The bus ribbons 145 may be arranged in the direction intersecting the ends of the solar cells 150 forming one row. The bus ribbon 145 may be connected to a junction box (not shown) that collects electricity generated by the solar cell 150 and prevents electricity from flowing backward.

However, the present invention is not limited thereto, and the connection structure between the solar cells 150, the connection structure between the solar cell 150 and the outside may be variously modified. Also, it is possible that the solar cell panel 100 is composed of one solar cell 150 without a plurality of solar cells 150.

The front substrate 110 is positioned on the sealing material 130 to constitute the front surface of the solar cell panel 100 and the rear sheet 120 is disposed on the sealing material 130 to constitute the rear surface of the solar cell panel 100 do. At this time, both the front substrate 100, the rear sheet 120, and the sealing material 130 have light transmittance, so that light incident on both sides of the solar cell panel 100 can be used for the solar cell 150. [ Here, the term "having transparency" means that the transmittance to light in the visible light region (for example, light having a wavelength of 300 to 800 nm) is 80% or more (that is, 80% to 100%, for example 85% or more) For example, it may be transparent because it does not include a separate pigment or the like.

In this embodiment, the front substrate 110 may include a transparent glass substrate. If the front substrate 110 is formed of a glass substrate, the solar cell 150 can be highly securely protected and the reliability of the solar cell panel 100 can be improved due to excellent translucency, durability, insulation characteristics, and moisture resistance. Particularly, since the front substrate 110 of the solar cell panel 100 is exposed to the outside, a problem caused by external impact including snow, rain, etc. can be generated more than the rear sheet 120, This problem can be effectively prevented.

The sealing material 130 prevents moisture and oxygen from flowing into the solar cell 150 and chemically combines the elements of the solar cell panel 100. The sealing material 130 includes an insulating material having translucency and adhesiveness as a base material. As used herein, the term " base material " means a material containing the most weight percentages in each layer. For example, the sealing material 130 may be composed of an ethylene vinyl acetate resin (EVA), a polyvinyl butyral, a silicon resin, an ester resin, an olefin resin, a polyethylene resin, an ionomer or the like.

In the present embodiment, the back sheet 120 may be composed of a sheet other than a glass substrate. Thus, since the glass substrate is not disposed on the rear surface of the solar cell panel 100, the thickness and weight of the solar cell panel 100 can be minimized, and ease of handling can be improved. In addition, it is possible to prevent air bubble problems and the like that may occur when using the glass substrate.

At this time, the back sheet 120 includes a transparent moisture-proof film 120b constituting the outer surface and composed of a compound containing aluminum and oxygen. More specifically, the back sheet 120 includes a sheet main body 120a including a resin and a transparent moisture-proof film 120b located on the outer surface side of the sheet main body 120a and composed of a compound containing aluminum and oxygen do. At this time, the moisture permeability of the transparent moisture-tight film 120b is lower than that of the sheet main body 120a and the hardness is high.

As described above, the aluminum and oxygen-containing compounds constituting the transparent moisture-proofing film 120b are excellent in light transmittance, low water permeability and high hardness as ceramic materials, and can exhibit moisture transmittance without lowering the light transmittance of the back sheet 120 And the hardness can be increased. Particularly, a compound containing aluminum and oxygen is a material having an excellent light transmittance, a low water permeability and a high hardness as compared with other ceramic materials. On the other hand, other ceramics are often difficult to have optical transparency. For example, titanium oxide and the like have a white color and are hardly light-transmissive.

That is, in the present embodiment, the back sheet 120 is provided with the sheet main body 120a made of resin and the transparent moisture-proof film 120b made of a ceramic material, which is a compound containing aluminum and oxygen, (For example, increase in thickness and weight, deterioration in ease of handling, and the like) when used, and can also have excellent moisture-proof and abrasion resistance.

In one embodiment, the transparent moisture-proof film (120b) is aluminum oxide (aluminum oxide) (For example, Al ₂ O _3), oxynitride of aluminum (aluminum oxynitride) (In one embodiment, AlON), magnesium aluminate (magnesium aluminate) (days For example, MgAl ₂ O ₄ ), and the like. Such materials are materials having excellent light transmittance, low water permeability and high hardness. As an example, the backsheet 120 may be composed of aluminum oxide, which may be readily formed by a variety of methods.

More specifically, the transparent moisture-proof film (120b) is 3 g / cm ³ or higher (For example, 3 to 4 g / cm ³⁾ having a density of at least 10 GPa (e.g., from 10 to 30 GPa, For example, 15 to 30 GPa), and may have a strength of 200 MPa or more (for example, 200 to 1000 MPa). For example, aluminum oxide having a density of 3.98 g / cm ^3, having a hardness of 22 GPa, it can have a strength of 400 to 800 MPa. Aluminum oxynitride has a density of 3.68 g / cm < ³ >, has a hardness of 18 GPa, and can have a strength of 300 to 400 MPa. Magnesium aluminate has a density of 3.58 g / cm < ³ >, has a hardness of 16 GPa, and can have a strength of 200 to 300 MPa.

By way of reference, the sheet body 120a may have a hardness of less than 10 GPa. The base member 121 constituting the sheet main body 120a may have a hardness of 4.5 Gpa or less and the first and / or second resin layers 123 and 124 may have a hardness of 1.6 GPa or less (for example, 0.3 GPa or less) It has hardness.

Since the compounds including aluminum and oxygen have high strength and hardness, the transparent moisture-proofing film 120b to which the present invention is applied can have high strength and hardness. Accordingly, the back sheet 120 to which the transparent moisture barrier layer 120b is applied can have excellent durability and abrasion resistance even though it is composed of the sheet body 120a using a resin as a base material rather than a glass substrate.

The water vapor transmission rate (WVTR) of the transparent moisture barrier film 120b or the back sheet 120 including the transparent moisture barrier film 120b may be 0.1 g / m ² · day or less. For reference, if the transparent moisture-proofing film 120b has a low moisture permeability, the backsheet 120 also has a moisture permeability corresponding thereto. This moisture permeability is significantly lower than the moisture permeability of the sheet main body 120a of 2 to 3 g / m ² · day. Therefore, the moisture-proof property can be greatly improved by the transparent moisture-proof film 120b composed of a compound containing oxygen and aluminum.

The backsheet 120 including the transparent moisture-proofing film 120b may have light transmittance as mentioned above. This is because the compound containing oxygen and aluminum contained in the transparent moisture-proofing film 120b has excellent light transmittance.

The transparent moisture-proofing film 120b may have a thickness smaller than that of the sheet body 120a. The sheet main body 120a may include a plurality of layers having different materials or compositions (that is, the base member 121, the first or second resin layers 123 and 124, the first or second adhesive layers 123a and 124a, And the like. The thickness of the transparent moisture-proofing film 120b may be smaller than that of each of the plurality of layers of the sheet body 120a.

In this embodiment, the transparent moisture-proof film 120b is formed as a single layer as shown in Fig. If the transparent moisture-proof film 120b is formed as a single layer, the structure can be simplified. At this time, the thickness of the transparent moisture-proof film 120b may be 1um or less, for example, 40nm to 500nm. If the thickness of the transparent moisture-impermeable film 120b is too large, the light transmittance is deteriorated. If the thickness is too small, the moisture-proof property may not be good. Therefore, the above-described thickness is limited to a thickness at which the transparent moisture-proofing film 120b has excellent light transmittance and excellent moisture-proof property (that is, low moisture permeability).

In this embodiment, the transparent moisture-proof film 120b may be formed by directly depositing, coating or the like on the sheet body 120a. Thus, the transparent moisture-proofing film 120b can be placed in contact with the sheet main body 120a without interposing another layer therebetween. Then, the rear sheet 120 according to the present embodiment can be easily manufactured by forming the transparent moisture-proofing film 120b in addition to the sheet body 120a used as the conventional rear sheet. At this time, the transparent moisture-proof film 120b may be formed entirely on the sheet body 120a or the back sheet 120 to improve the moisture-proof property and may be formed without patterning, thereby simplifying the manufacturing process. However, the present invention is not limited thereto, and an additional adhesive layer (not shown) may be further provided between the sheet body 120a and the transparent moisture-proofing film 120b. The transparent moisture-proofing film 120b may be formed by a lamination process, 120b to the seat body 120a.

As an example, the transparent moisture-proof film 120b may be formed by atomic layer deposition (ALD) or plasma atomic layer deposition (PEALD). Atomic layer deposition or plasma atomic layer deposition can be performed at a low temperature (for example, 100 to 200 ° C), so that the transparent moisture-proofing film 120b can be formed without damaging the sheet main body 120a.

Hereinafter, a process of forming the transparent moisture-proofing film 120b made of aluminum oxide by atomic layer deposition or plasma atomic layer deposition will be described as an example. Aluminum oxide is deposited on a layer-by-layer basis by alternately injecting a first raw material containing oxygen and a second raw material containing aluminum and purging the first raw material or the second raw material therebetween . As the first raw material, oxygen gas, ozone, water, etc. can be used, and as the second raw material, an aluminum compound including aluminum (for example, tri-methyl aluminum (TMA) According to the layer deposition process, the transparent moisture-proof film 120b can be formed thinly and uniformly by vapor deposition in units of layers, and the transparent moisture-proof film 120b can have more excellent moisture-proof property by densely filling aluminum oxide.

As another example, the transparent moisture-proof film 120b may be formed by applying a paste or solution containing aluminum oxide to the sheet body 120a and drying or baking. In this case, the paste may include aluminum oxide particles, a solvent, an additive, and the like. Examples of the solvent include solvents such as aromatic hydrocarbons, ethers, ketones, lactones, ether alcohols, esters, diesters, and mixtures thereof. Examples of the additives include acetylacetone, polyvinyl alcohol, And the like can be used. The thus formed transparent moisture-proofing film 120b may have a thickness of 1 mm or less (for example, 20 nm to 1 mm). At this time, the average particle diameter of the aluminum oxide particles may be 20 nm to 150 nm. When the average particle diameter of the aluminum particles is less than 20 nm, it is difficult to form the aluminum particles or the cost of the aluminum particles may be high. If the average particle diameter of the aluminum particles exceeds 150 nm, the transparent moisture-proof film 120b may not be uniformly formed. However, the present invention is not limited thereto.

For example, aluminum oxide particles may be contained in an amount of 40 to 60 parts by weight based on 100 parts by weight of the entire paste, and the solvent may be included in an amount of 40 to 60 parts by weight (for example, 35 to 55 parts by weight) . ≪ / RTI >

The above-mentioned paste can be applied to the sheet body 120a by roll coating or the like and can be dried or fired at a temperature of from 80 캜 to 150 캜. Thus, the desired transparent moisture-proofing film 120b can be formed.

Various structures known as the seat body 120a included in the back sheet 120 according to the present embodiment can be applied. Hereinafter, an example of the seat body 120a is described, but the present invention is not limited thereto.

The sheet main body 120a according to the present embodiment is disposed on the first resin layer 123 and the first resin layer 123 adjacent to the sealing material 130 and is disposed on the first resin layer 123 and another material And a second resin layer 124 disposed on the base member 121. The second resin layer 124 includes a base member 121 having a base member 121, A first adhesive layer 123a for bonding the first resin layer 123 to the base member 121 and a second adhesive layer 124a for bonding the base member 121 to the second resin layer 124 can do. The seat main body 120a may be integrated by a lamination process. The second resin layer 124 may or may not be included depending on the materials and / or characteristics of the first resin layer 123 and the base member 121 in this embodiment. Alternatively, at least one of the base member 121, the first resin layer 123 and the second resin layer 124 may include an adhesive material, or the first and second resin layers 123, The second resin layers 123 and 124 may be formed by coating. In this case, the first and / or second adhesive layers 123a and 124a may not be provided.

The base member 121 can serve as a base member for supporting the first resin layer 123 and / or the second resin layer 124. And the base member 121 can have an excellent insulating property to improve the insulating property of the rear sheet 120. [ For this purpose, the base member 121 has better insulating properties than the first resin layer 123 and / or the second resin layer 124 and can have a high mechanical strength. For example, the base member 121 may include a resin, and may include, for example, polyamide or polyester as a base material. The polyester is excellent in protecting the solar cell 150 because of its excellent mechanical properties, thermal characteristics, electrical characteristics, formability, chemical resistance and the like. For example, the polyester may be a conventional polyester or an aqueous polyester. At this time, the polyester may include polyethylene terephthalate (PET). The polyethylene terephthalate is excellent in heat resistance, weather resistance, insulation, mechanical strength and the like, and has a small molding shrinkage ratio, so that deformation of the sheet body 120a due to heat can be prevented.

As the base member 121, there can be used a sheet-like (or film-like) sheet made of the above-mentioned resin by various methods. However, the present invention is not limited thereto, and the base member 121 can be manufactured by various methods.

The first resin layer 123 located opposite to (for example, in contact with) the sealing material 130 is a layer for adhering to the sealing material 130. The adhesive force to the sealing member 130 is higher than that of the base member 121 and / or the second resin layer 124 (particularly, the base member 121). In consideration of this, the first resin layer 123 may include a fluoro polymer or a polyolefin-based material as a base material. The fluorine-based polymer will be described in detail later in the second resin layer 124. The first resin layer 123 can use the same fluorine-based material as the second resin layer 124 to improve the environmental resistance and reliability of the backsheet 120. Alternatively, the first resin layer 123 may include a polyolefin-based material to reduce the material cost of the backsheet 120. Examples of the polyolefin-based material that can be contained in the first resin layer 123 include ethylene-vinyl acetate (EVA), polyethylene (PE), and polypropylene (PP).

The second resin layer 124 positioned (e.g., in contact with) the base member 121 is a layer positioned outwardly from the sheet body 120a and has excellent environmental resistance (i.e., stability against heat and moisture and durability against ultraviolet ) Can be composed of excellent materials. That is, the heat and moisture stability of the second resin layer 124 and the durability against ultraviolet rays can be improved by the heat of the first resin layer 123 and / or the heat of the base member 121 (particularly, the base member 121) And the durability against ultraviolet rays may be higher. At this time, the transparent moisture-proof film 120b may contact the second resin layer 124 when the second resin layer 124 is present, and may contact the second resin layer 124 when the second resin layer 124 is not present. Can be contacted.

In consideration of this, the second resin layer 124 may include a fluorine-based polymer, a polyester (e.g., polyethylene terephthalate), or a polyamide-based material as a base material. Particularly, the second resin layer 124 is formed of a fluorine resin such as polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), ethylene tetrafluoroethylene (ETFE) It can be included as resin. The fluorine-based resin is excellent in weather resistance, chemical resistance and the like since it does not have a bond that may cause hydrolysis. Particularly, polyvinylidene fluoride is a polymer having a structure of (CH ₂ CF ₂ ) n and has a double fluorine molecular structure, and thus has excellent mechanical properties, weather resistance, chemical resistance and ultraviolet ray resistance. Various other base materials may be used for the second resin layer 124, and the present invention is not limited thereto.

The above-described seat main body 120a can have optical transparency. That is, the sheet main body 120a can have a light transmittance of 80% or more (for example, 85% or more) with respect to light in the visible light region, and can be transparent without including a separate pigment.

The first resin layer 123 and the second resin layer 124 may be formed of the same material or different materials. At this time, the materials of the first resin layer 123 and the second resin layer 124 may be selected according to desired characteristics. For example, the first resin layer 123 may include a polyolefin-based material that is relatively inexpensive, and the second resin layer 124 may include a fluoropolymer having excellent environmental resistance.

For example, the first resin layer 123 may have a thickness of 5 to 250 mu m. If the thickness of the first resin layer 123 is less than 5 μm, the adhesion between the first resin layer 123 and the second sealant 132 may not be excellent, and if the thickness of the first resin layer 123 exceeds 250 μm The material cost may increase and the thickness of the solar cell panel 100 may increase. The thickness of the base member 121 may be 30 to 400 mu m. If the thickness of the base member 121 is less than 30 탆, it may be difficult to have sufficient insulating properties, moisture barrier properties and mechanical strength. If the thickness of the base member 121 exceeds 400 袖 m, the handling is inconvenient, the material cost increases, and the thickness of the solar cell panel 100 may become thick. And the thickness of the second resin layer 124 may be 0 to 60 탆. Since the material of the second resin layer 124 is expensive due to the use of a material having excellent ultraviolet durability, the second resin layer 124 can be formed to have a thickness of 60um or less, thereby reducing the cost.

Alternatively, the thickness of the base member 121 may be greater than the thickness of the first resin layer 123 and the second resin layer 124, respectively. The thickness of the second resin layer 124 may be equal to or less than the thickness of the first resin layer 123. This is because the second resin layer 124 having high durability due to ultraviolet rays has a relatively thick material so that the base member 121 has a sufficient thickness to support the rear sheet 120, To reduce material costs. However, the present invention is not limited thereto, and the thicknesses of the base member 121, the first resin layer 123, and the second resin layer 124 may be variously changed.

The first adhesive layer 123a and the second adhesive layer 124a which are located between the first resin layer 123 and the base member 121 or between the base member 121 and the second resin layer 124 and which adhere them are bonded The material may be included as a base material. For example, as an adhesive material, urethane-based or acrylic-based adhesive materials having excellent adhesive properties and low material cost can be used. However, the present invention is not limited thereto and various adhesive materials can be used.

The thickness of the first and / or second adhesive layers 123a and 124a may be smaller than the base member 121 serving as the base member and the thickness of the first resin layer 123 and / or the second resin layer 124 ( (Particularly, the first resin layer 123). This is because the first or second adhesive layer 123a or 124a may have only a thickness enough to have adhesive properties. In one example, the thickness of the first and / or second adhesive layer 123a, 124a may be between 3 um and 30 um. If the thickness of the first and / or second adhesive layers 123a and 124a is less than 3 占 퐉, the adhesive properties of the first and / or second adhesive layers 123a and 124a may be deteriorated. If the thickness of the first and / or second adhesive layers 123a and 124a exceeds 30 mu m, the thickness of the back sheet 120 becomes thick and the material cost may increase. However, the present invention is not limited thereto and various modifications are possible.

However, since the base member 121, the first and second resin layers 123 and 124 may have various thicknesses as described above, the present invention is not limited thereto. The thickness of the first and / or second adhesive layers 123a and 124a may be equal to or greater than the thickness of the base member 121, the first and second resin layers 123 and 124, and the like. As an example, the sheet body 120a made of a resin sheet may have a thickness of 35 to 1000um (for example, 100um to 1000um).

The solar cell panel 100 according to the present embodiment is formed by integrating the back sheet 120, the second sealing material 132, the solar cell 150, the first sealing material 131 and the front substrate 110 by a lamination process or the like Can be formed.

According to the present embodiment, the back sheet 120 has a transparent moisture-proof film 120b made of a compound containing aluminum and oxygen on its outer surface, and can have excellent light-transmitting property, moisture-proof property and abrasion resistance. Accordingly, the solar cell module 100 is applied to the solar cell panel 100 having a double-side light-receiving structure, so that it can have excellent moisture-proof property and abrasion resistance without interfering with light incident on the rear surface. As a result, it is possible to prevent the problem of using a glass substrate on the rear surface and to exhibit excellent moisture-proof and abrasion resistance as a glass substrate.

Hereinafter, a back sheet according to another embodiment of the present invention will be described in detail with reference to FIGS. 5 and 6. FIG. For simplicity and clarity, only the portions corresponding to the enlargement circle in Fig. 2 are shown in Fig. 5 and Fig. Hereinafter, the same or similar portions as those of the above-described embodiments may be applied to the above description, and thus detailed description will be omitted and only different portions will be described in detail. It is also within the scope of the present invention to combine the above-described embodiments or variations thereof with the following embodiments or modifications thereof.

5 is a partially enlarged cross-sectional view of a solar cell panel according to another embodiment of the present invention. For clarity and simplicity, only the portion corresponding to the enlargement circle in Fig. 2 is shown in Fig.

Referring to FIG. 5, in this embodiment, the transparent moisture-proof film 120b may include a plurality of layers 121b and 122b including different materials or compositions. When the transparent moisture-proof film 120b includes a plurality of layers 121b and 122b, moisture resistance and strength can be further improved.

At this time, each of the layers 121 and 122b of the transparent moisture-shielding film 120b may include one of the above-mentioned compounds containing aluminum and oxygen. The first layer 121b located on the outer surface of the transparent moisture barrier layer 120b may include one of aluminum oxide, aluminum oxynitride and magnesium aluminate, and may include a sheet body 120a rather than the first layer 121b, The second layer 122b adjacent to the second layer 122b may include another one of aluminum oxide, aluminum oxynitride, and magnesium aluminate. Here, the first layer 121b located on the outer surface has a hardness higher than that of the second layer 122b located on the inner surface, so that the wear resistance of the back sheet 120 can be improved. For example, if the first layer 121b comprises aluminum oxide and the second layer 122b comprises aluminum oxynitride or magnesium aluminate, or if the first layer 121b comprises aluminum oxynitride, And the second layer 122b may contain magnesium aluminate.

As another example, at least one of the plurality of layers 121b and 122b of the transparent moisture-shielding film 120b may include one of the above-mentioned compounds containing aluminum and oxygen, and at least the other may include another transparent ceramic material . For example, yttrium oxide or the like can be used as another transparent ceramic material. Here, the first layer 121b located on the outer surface has a hardness higher than that of the second layer 122b located on the inner surface, so that the wear resistance of the back sheet 120 can be improved. For example, the first layer 121b may comprise a compound comprising oxygen and aluminum having high strength and moisture resistance as described above, and the second layer 122b may comprise another transparent ceramic material have.

In FIG. 5, the transparent moisture-proof film 120b is composed of two layers 121b and 122b. However, the present invention is not limited thereto. The transparent moisture-proof film 120b may be composed of three or more layers.

In this embodiment, the transparent moisture-proofing film 120b including the plurality of layers 121b and 122b may be formed by directly depositing or coating the sheet body 120a. When the deposition is used, a desired plurality of layers 121b and 122b can be formed by changing the source gas to be provided. In the case of using the coating, the desired layer (121b, 122b) can be formed by repeating the process of applying and drying the paste to form the desired layer.

At this time, the total thickness of the transparent moisture-proof film 120b or the thickness of each of the layers 121b and 122b constituting the transparent moisture-proof film 120b may be 1um or less, for example, 40nm to 500nm. If the thickness of the transparent moisture-impermeable film 120b or each of the layers 121b and 122b constituting the transparent moisture-impermeable film 120b is too large, the light transmittance may deteriorate. If the thickness is too small, the moisture-proof property may not be good. Therefore, the above-mentioned thickness is limited to a thickness at which the transparent moisture-proofing film 120b has excellent light transmittance and excellent moisture-proof property (that is, low moisture permeability). However, the present invention is not limited thereto. Therefore, the total thickness of the transparent moisture-proof film 120b may be larger than 1 um by the thickness, number, etc. of the plurality of layers 121b and 122b constituting the transparent moisture-proof film 120b.

6 is a partially enlarged cross-sectional view of a solar cell panel according to another embodiment of the present invention. For clarity and simplicity, only the portion corresponding to the enlargement circle in Fig. 2 is shown in Fig.

6, the rear sheet 120 according to the present embodiment includes a transparent moisture-proof film 120b (hereinafter referred to as a first transparent moisture-proof film 120b) positioned on the outer surface, a first transparent moisture- (Hereinafter referred to as a second transparent moisture-proofing film 120c) which is located on the opposite side of the sealing material 130 and is adjacent to the sealing material 130. [

For example, the second transparent moisture-proof film 120c may be composed of a compound containing oxygen and aluminum, like the first transparent moisture-proof film 120b. More specifically, the first and second transparent moisture-proof films 120b and 120c may have the same material and composition. The first and second transparent moisture-proof films 120b and 120c may be formed on both sides of the sheet main body 120a at the same time in the same deposition process or the first and second transparent moisture-proof films 120b and 120c may be formed using the same paste Coating process or the like. Thus, the manufacturing process can be simplified.

Alternatively, the second transparent moisture-proofing film 120c is made of a compound containing oxygen and aluminum in the same manner as the first transparent moisture-proofing film 120b, but may include a composition different from that of the first transparent moisture-proofing film 120b. Thus, the first transparent moisture-proof film 120b located on the outer surface includes a material having hardness, strength, and moisture permeability superior to that of the second transparent moisture-proof film 120c, and the second transparent moisture- A material having an excellent adhesive force to the sealing material 130 than the transparent moisture-proofing film 120c.

Alternatively, the second transparent moisture-proof film 120c may be a transparent ceramic material having a material or composition different from that of the first transparent moisture-proof film 120b. Various other examples are possible.

In the embodiment described with reference to Figs. 1 and 2 or 5, the description of the first transparent moisture-proofing film 120b can be directly applied to the second transparent moisture-proofing film 120c.

In this embodiment, the adhesive layer 120d may be further included on the second transparent moisture-proofing layer 120c. The adhesive layer 120d may be a material capable of improving the adhesion property between the second transparent moisture-proofing film 120c, which is a ceramic material, and the sealing material 130. [ In one example, the adhesive layer 120d may include a pressure-sensitive adhesive material (PSA) comprising a urethane-based material or a silicone-based material. In particular, the adhesive layer 120d may include a silicon-based material different from the first and second adhesive layers 123a and 124a included in the sheet body 120a so as to have excellent adhesiveness. However, the present invention is not limited thereto. For example, the adhesive layer 120d may include the same material (for example, a urethane material) as the first and second adhesive layers 123a and 124a included in the sheet body 120a. Further, the adhesive layer 120d is not essential, and it is also possible that the adhesive layer 120d is not provided.

Features, structures, effects and the like according to the above-described embodiments are included in at least one embodiment of the present invention, and the present invention is not limited to only one embodiment. Further, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified in other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

100: Solar panel
110: front substrate
120: Rear Sheet
120a:
120b and 120c: a transparent moisture-
120d:
130: Seal material
150: Solar cell

Claims (20)

A solar cell having a double-side light-receiving structure;
A front substrate disposed on a front surface of the solar cell and having a light transmitting property;
A back sheet disposed on a rear surface of the solar cell and having a light transmitting property; And
And a sealing material disposed between the front substrate and the rear sheet while surrounding the solar cell,
Lt; / RTI >
Wherein the back sheet comprises a transparent moisture-proofing film constituting an outer surface and composed of a compound containing aluminum and oxygen. The method according to claim 1,
Wherein the back sheet comprises a sheet body including a resin and the transparent moisture-proof film located on an outer surface side of the sheet body,
Wherein the transparent moisture barrier film has a lower moisture permeability and a higher hardness than the sheet body. The method according to claim 1,
Wherein the transparent moisture barrier film has a hardness of 10 GPa or more and a strength of 200 MPa or more. The method according to claim 1,
Wherein a moisture vapor transmission rate (WVTR) of the rear sheet or the transparent moisture barrier film is 0.1 g / m ² · day or less. 3. The method of claim 2,
Wherein a thickness of the transparent moisture-proofing film is smaller than that of the sheet body. The method according to claim 1,
Wherein the thickness of each layer constituting the transparent humidity-proof film or the transparent moisture-proof film is 1um or less. The method according to claim 6,
Wherein the thickness of each of the layers constituting the transparent moisture-proofing film or the transparent moisture-proofing film is 40 nm to 500 nm. The method according to claim 1,
Wherein a light transmittance of the back sheet to light having a wavelength of 300 nm to 800 nm is 80% or more. The method according to claim 1,
Wherein the transparent moisture-barrier film comprises at least one of aluminum oxide, aluminum oxynitride, and magnesium aluminate. 10. The method of claim 9,
Wherein the transparent moisture-proofing film is a single layer including an aluminum oxide layer containing aluminum oxide. 3. The method of claim 2,
Wherein the transparent moisture-proof film contacts the sheet body and is formed entirely on the sheet body. The method according to claim 1,
Wherein the transparent moisture-proofing film comprises a plurality of layers including different materials or compositions. 13. The method of claim 12,
Wherein the plurality of layers of the transparent moisture-proofing film comprise a first layer located on the outer surface and a second layer located between the sealing material and the first layer,
Wherein the first layer has a higher hardness than the second layer. 14. The method of claim 13,
Wherein the first layer and the second layer include a compound containing aluminum and oxygen, the compositions being different from each other. 15. The method of claim 14,
Wherein the first layer comprises aluminum oxide and the second layer comprises aluminum oxalate or magnesium aluminate; or
Wherein the first layer comprises aluminum oxynitride and the second layer comprises magnesium aluminate. 14. The method of claim 13,
Wherein the first layer comprises a compound comprising aluminum and oxygen,
Wherein the second layer comprises a transparent ceramic material different from the compound comprising aluminum and oxygen. The method according to claim 1,
Wherein another transparent moisture-shielding film comprised of aluminum and oxygen-containing compound is located on a surface of the rear sheet that is in contact with the sealing material. 1. A back sheet for a solar cell panel,
And a transparent moisture-proofing film composed of a compound containing aluminum and oxygen on the outer surface. 19. The method of claim 18,
Wherein the back sheet comprises a sheet body including a resin and the transparent moisture-proof film located on an outer surface side of the sheet body,
Wherein the transparent moisture-proofing film has a lower moisture permeability and a higher hardness than the sheet body. 19. The method of claim 18,
Wherein the transparent moisture barrier film comprises at least one of aluminum oxide, aluminum oxynitride and magnesium aluminate.

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