KR20160120950A

KR20160120950A - Encapsulation for a photovoltaic module

Info

Publication number: KR20160120950A
Application number: KR1020150050181A
Authority: KR
Inventors: 박효순; 김현철; 정재식
Original assignee: 주식회사 엘지화학
Priority date: 2015-04-09
Filing date: 2015-04-09
Publication date: 2016-10-19
Also published as: KR101742865B1

Abstract

The present application relates to an encapsulant for a photovoltaic module, a method for producing the encapsulant, and a photovoltaic module including the encapsulant. The encapsulant of the present application includes a layer containing glass fibers, and it is possible to secure excellent flame retardancy. Also, when the layer including the glass fiber of the encapsulant is attached to the backsheet, excellent adhesion can be ensured, and a good appearance can be obtained when the layer is made of a photovoltaic module.

Description

{ENCAPSULATION FOR A PHOTOVOLTAIC MODULE}

The present application relates to an encapsulant for a photovoltaic module, a method for producing the encapsulant, and a photovoltaic module including the encapsulant.

Recently, global environmental problems and depletion of fossil fuels have raised interest in renewable energy and clean energy. Among them, energy using light is attracting attention as a representative pollution-free energy source that can solve environmental pollution problem and fossil fuel depletion problem. Particularly, photovoltaic cells such as solar cells are rapidly spreading in residential and industrial fields.

Photovoltaic cells are devices that convert sunlight to electrical energy, which typically require long exposure to the external environment to easily absorb sunlight, so that various packaging to protect the internal components is performed, And these units are commonly referred to as photovoltaic modules.

In addition, most optical modules include an encapsulant for protecting internal components (e.g., solar cells).

Generally, in the case of a photovoltaic module, a transparent front member on which light is incident, an encapsulant layer in which a plurality of solar cell cells are encapsulated, and a back sheet are sequentially stacked.

As the transparent front member, a tempered glass or a front sheet is mainly used. The plurality of solar cells are electrically connected to each other, and are packed and sealed by the sealing material layer. The back sheet is attached to the lower surface of the solar cell module, that is, the lower surface of the sealing material, to protect the photovoltaic cell.

The encapsulant has a problem in that the flame retardancy such as burning or melting mostly occurs when exposed to a flame or the like.

In order to improve this, a technique of using an inorganic component in an encapsulant layer used on the back side of the encapsulant layer has been attempted. For example, Korean Patent Publication No. 2011-0069180 discloses a technique for an encapsulant containing an inorganic component. However, when an inorganic component is included, the adhesive strength to the substrate is lowered, and a separate processing step is required. Accordingly, the production cost is increased, and in particular, when the inorganic component is included, There is a problem that the encapsulant is raised above the photovoltaic cell.

Therefore, an encapsulant for a photovoltaic module and a photovoltaic module using the encapsulant for the photovoltaic module, which have excellent adhesiveness and appearance, are required.

Patent Document 1: Korean Patent Publication No. 2011-0069180

The present application provides an encapsulant for a photovoltaic module, a method of making the encapsulant, and a photovoltaic module including the encapsulant.

The present application relates to an encapsulating layer.

As used herein, the term "sealing layer" may mean any layer included in an encapsulating material for sealing (packing, fixing) the photovoltaic cell as described later.

In one example, the encapsulant layer 100 may have a multilayer structure, as shown in Figure 1, and may include, for example, a first layer 10 comprising an ethylenic copolymer; And a second layer 20 comprising glass fibers.

The ethylene-based copolymer is not particularly limited, but may include, for example, an ethylene-vinyl acetate copolymer (EVA) or an ethylene-alpha olefin copolymer (POE).

The ethylene-vinyl copolymer (EVA) is a polymer produced by the copolymerization reaction of ethylene and vinyl acetate (VA).

When the ethylene-vinyl copolymer is included in the encapsulating layer, the generation efficiency of the photovoltaic cell can be prevented from being lowered by blocking the yellowing due to ultraviolet absorption even when the photovoltaic cell is used for a long period of time by exposure to the external environment. Production is possible.

The ethylene-alpha olefin copolymer may be a polyolefin-based copolymer such as a polyethylene copolymer, a polypropylene copolymer, an ethylene / propylene copolymer, and an ethylene / propylene / butadiene copolymer, but is not limited thereto.

In addition to the ethylenic copolymer, the sealing layer may further contain additives such as an ultraviolet absorber, a crosslinking agent, a crosslinking assistant, an antioxidant, a plasticizer, a dispersant, a surfactant, an antistatic agent, a defoaming agent, a leveling agent, a silane coupling agent, Purpose can be achieved.

The present invention also relates to an encapsulant comprising the encapsulation layer.

In one example, the encapsulant may comprise an encapsulant for a photovoltaic module.

As shown in FIG. 2, the encapsulating material includes a front encapsulating layer 30; At least two photovoltaic cells (40) formed on at least one surface of the front seal layer (30) and spaced apart from each other; And a back surface encapsulating layer 50 sealing the photovoltaic cell 40. The back surface encapsulating layer 50 may include the encapsulation layer 100 described above.

The material of the front sealing layer is not particularly limited as long as it has adhesiveness and insulating properties, and may include an ethylenic copolymer as a main component of the sealing layer. The description of the ethylenic copolymer is as described above.

The plurality of photovoltaic cells are arranged in an encapsulating material. That is, the photovoltaic cell may be sealed (packed, fixed) in a state where a plurality of the photovoltaic cells are arranged between the front encapsulation layer and the backside encapsulation layer. The plurality of photovoltaic cells are electrically connected to each other.

The photovoltaic cell is not particularly limited, but may be selected from, for example, a crystalline photovoltaic cell and / or a thin film photovoltaic cell. In addition, in the present application, the photovoltaic cell may include a front electrode type, a back electrode type, or a combination thereof.

The backside sealing layer may be encapsulating the photovoltaic cell in the backside of the photovoltaic module, which will be described later. The backside sealing layer may include a sealing layer, that is, a first layer including the ethylenic copolymer as a laminate structure, And a sealing layer having a laminated structure of

The backside sealing layer is not particularly limited, but for example, the first layer may be arranged to be attached to the photovoltaic cell. In order to encapsulate the photovoltaic cell, an adhesive force and an insulating property are required. Therefore, the first layer may include an ethylenic copolymer as described above.

The second layer containing the glass fibers is not particularly limited, but may be disposed so as to adhere to a back sheet formed on the back surface in a later-described photovoltaic module.

In the present application, the second layer containing the glass fibers is contained in the encapsulating material and is applied to the photovoltaic module, thereby ensuring excellent flame retardancy. When the glass fiber is included, the glass fiber has a strong resistance to flame, so that the sealing material is prevented from being exposed to the flame to burn or melt.

In the present application, the second layer containing the glass fiber is not particularly limited as long as it contains conventional glass fibers, but may include glass fiber sheets and / or glass fiber pulverized materials, for example. Or the second layer containing the glass fiber may include a glass fiber layer having a multilayer structure in which one or two or more glass fiber sheets are laminated according to an exemplary embodiment.

The glass fiber sheet may be selected from a woven fabric and / or a non-woven fabric. According to one embodiment, the glass fiber sheet can be selected from a fabric. More specifically, a glass fiber sheet can be selected from a woven glass fiber sheet made by weaving glass fiber strands through a weaving process. Such a fabric-type glass fiber sheet can be advantageous in flame retardancy while having excellent mechanical strength as compared with nonwoven fabric type.

In one example, the second layer comprising the glass fibers may further comprise a fluorine-based resin, if necessary. The fluorine-based resin can be applied to the second layer by, for example, impregnation or coating. Such a fluorine resin effectively improves flame retardancy as well as mechanical strength and the like of the second layer, thereby ultimately increasing the resistance of the encapsulant to the flame containing it.

The second layer glass fiber sheet and the fluororesin dispersed in the glass fiber sheet. The glass fiber sheet may have a structure in which the fluorine resin is dispersed and fixed on the surface of the glass fiber sheet as well as the inner fiber tissue by impregnating the fluorine resin with the fluorine resin.

In another example, the second layer may comprise a glass fiber sheet and a fluorine resin layer in the form coated on the glass fiber sheet.

In another example, the second layer may comprise a glass fiber milled product and a fluorine resin. In this case, the glass fiber milled product is obtained by grinding the glass fiber sheet in the second layer, A fluorine resin liquid, and then molding it into a sheet form.

In the case where the glass fiber is in the form of a pulverized product, it is not particularly limited. For example, the average particle diameter may be in the range of 1 탆 to 30 탆, 5 탆 to 15 탆, or 9 탆 to 13 탆. In this case, the glass fiber pulverized product can be dispersed more efficiently, and excellent flame retardancy can be ensured.

In one example, the thickness of the second layer comprising glass fibers contained in the back side sealing layer may be more than 10 탆 and less than 1,000 탆, preferably 25 탆 to 750 탆 or 50 탆 to 500 탆.

By adjusting the thickness of the second layer in the above-mentioned range, the flame retardancy can be ensured and the adhesive strength to the back sheet can be ensured. More specifically, when the thickness of the second layer is 10 탆 or less, the flame retardancy is very low, and when the thickness is 1,000 탆 or more, the adhesive strength to the back sheet may be very low.

In one example, the encapsulant of the present application can satisfy Equation 1 below with respect to the improvement of adhesion.

[Equation 1]

X ≥ 0.5 kgf / 10 mm

X represents the adhesive force when the sealing material is peeled off at a peeling angle of 180 degrees and a peeling rate of 300 mm / min after attaching the sealing material to the back sheet at 160 캜 for 17 minutes in a width of 10 mm.

In the above formula (1), the X value may be 1.0 kgf / 10 mm or more, 2.0 kgf / 10 mm or more, 2.5 kgf / 10 mm or more, or 3.0 kgf / 10 mm or more.

Specifically, the experimental method and the measurement conditions for deriving Equation (1) will be described later in the " Adhesion Force Measurement " section.

In the present application, the backside sealing layer can be produced, for example, in the form of a film by first preparing a first layer comprising the ethylenic copolymer and a second layer comprising glass fibers, A detailed description will be given later.

In one example, the back side encapsulating layer may not contain inorganic particles. As the inorganic particles, for example, aluminum hydroxide, magnesium hydroxide, antimony oxide or bromine may be exemplified as the particles to be introduced for the conventional flame retardancy, and the backside sealing layer of the present application may contain no such flame- have.

The encapsulant of the present application does not contain flame-retardant inorganic particles and instead, a back-seal layer containing a glass fiber-containing layer is appropriately arranged to ensure better flame retardancy, and at the same time, The color change can be prevented more efficiently.

In one example, the encapsulant of the present application can satisfy Equation 2 below.

[Equation 2]

Y? 150

In the formula (2), Y represents the time required for the 75 mm length portion of the specimen to ignite after attaching the encapsulant to the back sheet at 160 캜 for 17 minutes at 12.5 mm x 125 mm (width x length) (Seconds).

Specific experimental methods and measurement conditions for deriving Equation (2) will be described later in the " Flammability Measurement " section.

The present application also relates to a method for manufacturing an encapsulant.

Exemplary methods for producing the encapsulation material may include a step of laminating a first layer containing the ethylenic copolymer and a second layer comprising glass fibers to produce a back side encapsulation layer.

In this case, the first layer and / or the second layer may be respectively formed in the form of a film or a sheet and then subjected to a process of laminating them.

Alternatively, the first layer and / or the second layer may be formed by preparing one of the layers in the form of a film or a sheet, and then coating and drying another layer on the film or sheet.

The laminating method may be selected from a roll lining method, a heat lining method, an adhesive method, or a laminating method by hot-melt method, but is not limited thereto.

The coating and drying process may be carried out without any limitations.

The present application also relates to photovoltaic modules.

An exemplary photovoltaic module includes a front substrate 200; A back sheet 400; And the encapsulant 300 between the front substrate 200 and the back sheet 400.

The front substrate can be selected and used without particular limitation as long as it provides a light receiving surface while protecting the front side (the upper side in FIG. 3) of the photovoltaic cell. In addition, it is preferable to use a material having excellent light transmittance because the front substrate has better power generation efficiency of the photovoltaic module as the light transmittance is better. As the front substrate, a transparent substrate favorable for light incidence, for example, may be composed of a rigid substrate such as glass or transparent plastic, a flexible transparent resin sheet, or the like, but is not limited thereto.

The backsheet is preferably attached to the lower surface of the encapsulant, that is, to the second layer comprising glass fibers of the back side encapsulant.

The method of attaching the backsheet and the second layer of the back side encapsulation layer may be adhered through thermal lamination (heat fusion), adhesive, or the like. The adhesive is not particularly limited, and one or more adhesives selected from, for example, an acrylic adhesive, a urethane adhesive, an epoxy adhesive, and a polyolefin adhesive may be used, but the adhesive is not limited thereto.

The backsheet may further include various functional layers as required. Examples of the functional layer include, but are not limited to, an ultraviolet blocking layer, an adhesive layer, an insulating layer and / or a primer layer.

The photovoltaic module of the present application may include the front substrate and the back sheet, and the sealing material existing between the front substrate and the back sheet. Accordingly, the photovoltaic module of the present application can exhibit flame retardancy due to flame, at the same time securing excellent adhesion with the backsheet, and showing good appearance without changing appearance or color after production.

The optical module according to the present application may further include a rear member if necessary. The backing member may be attached to the back side of the back sheet, i.e., the opposite side of the back side backing layer. The rear member may be selectively included depending on the type of the optical module and the installation place, and may be selected from a rigid substrate such as the glass (for example, tempered glass) or a transparent plastic plate.

The encapsulant of the present application includes a layer containing glass fibers, and it is possible to secure excellent flame retardancy. Also, when the layer including the glass fiber of the encapsulant is attached to the backsheet, excellent adhesion can be ensured, and a good appearance can be obtained when the layer is made of a photovoltaic module.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram schematically showing a sealing layer of the present application. FIG.
2 is a view schematically showing an encapsulant of the present application.
3 is a diagram schematically showing the photovoltaic module of the present application.
Figs. 4 to 7 are diagrams schematically showing the photovoltaic module of Example 2 and Comparative Examples 1 to 3 of the present application. Fig.
8 is a diagram schematically showing specimens to be ignited for evaluating the flame retardancy of the photovoltaic module in the examples and comparative examples.

Hereinafter, the present application will be described in detail by way of examples and comparative examples according to the present application, but the scope of the present application is not limited by the following examples and comparative examples.

The physical properties of the photovoltaic module according to each of the examples and comparative examples were measured and evaluated in the following manner.

1. Flammability measurement

The photovoltaic module prepared in Examples and Comparative Examples was cut into 12.5 mm × 125 mm lengths of specimens, and a fire was radiated to one end of the specimen for 10 seconds. Then, a point at a distance of 25 mm from the end where the fire was radiated was regarded as a measurement start point, and a time at which a point 100 mm away from the end was ignited to the measurement end point was measured. That is, the time interval from the start point (25 mm) to the end point (100 mm) was measured as the measurement interval (75 mm), and the measurement time of the measurement interval (75 mm) was measured. FIG. 8 is a diagram schematically showing an ignited specimen including the measurement period. The measured ignition times are shown in Table 1 below.

2. Adhesion measurement

The photovoltaic module manufactured in Examples and Comparative Examples was cut into 12.5 mm × 100 mm length pieces. The adhesive force between the encapsulant and the back sheet of the specimen was measured using a universal testing machine (UTM) By using a peeling angle of 180 DEG and a peeling speed of 300 mm / min. The measured adhesive strength is shown in Table 1 below.

3. Appearance evaluation

The appearance of the photovoltaic module manufactured in Examples and Comparative Examples was visually observed and evaluated according to the following evaluation criteria, and is shown in Table 1.

Good: If the encapsulant does not climb over the photovoltaic cell

Defective: When the encapsulant is raised above the photovoltaic cell

Example One

< Encapsulant Manufacturing>

100 parts by weight of an ethylene-vinyl acetate resin (EP28025, manufactured by LG Chemical Co., Ltd.) having 28% by weight of vinyl acetate and a melt flow index at 190 DEG C of 25 g / 10 min, 0.5 part by weight of a silane coupling agent (Z-6030, manufactured by Daew Coating Co., Ltd.), 0.2 parts by weight of an ultraviolet stabilizer (songlight7700, manufactured by Songwon Industrial Co., Ltd.) 0.2 0.2 parts by weight of an antioxidant (Irganox 1076, manufactured by BASF) and 0.2 parts by weight of an ultraviolet absorber (UV531, manufactured by Cytec Co., Ltd.) were charged to prepare an EVA resin composition. Mu m. When the EVA resin composition is extruded out, a glass fiber layer (second layer) having a thickness of 100 mu m is laminated in a molding machine to form a back side sealing layer having a thickness 600 (thickness) including a glass fiber layer (second layer) and an EVA resin Mu] m.

<Fabrication of photovoltaic module>

(LBS-CFE, manufactured by LG Chemical Co., Ltd.) were successively laminated on the glass substrate, the above-prepared front encapsulation layer, the solar cell, the prepared back-encapsulation layer and the back sheet, A vacuum time of 6 minutes, a pressing pressure of 95 kPa and a pressing time of 10 minutes.

Example 2

Ethylene-embodiment, except that, including the alpha-olefin copolymer (LC885x (melt flow index of 20g / 10min), (Day) LG chemistry of the density ^{0.885g / cm 3, 190 ℃)} - vinyl acetate copolymer instead of ethylene An encapsulant and a photovoltaic module were prepared in the same manner as in Example 1. The photovoltaic module manufactured in Example 2 is schematically shown in Fig.

Comparative Example One

An encapsulant and a photovoltaic module were prepared in the same manner as in Example 1, except that the encapsulating material was used as the backside encapsulating layer in which the second layer containing glass fibers was not formed. The photovoltaic module manufactured in Comparative Example 1 is schematically shown in Fig.

Comparative Example 2

An encapsulant and a photovoltaic module were prepared in the same manner as in Comparative Example 1, except that an ethylene-alpha olefin copolymer was used in place of the ethylene-vinyl acetate copolymer. The photovoltaic module manufactured in Comparative Example 2 is schematically shown in Fig.

Comparative Example 3

An encapsulant and a photovoltaic module were prepared in the same manner as in Comparative Example 1, except that the backside sealing layer contained about 10% by weight of aluminum hydroxide as flame retardant inorganic particles in addition to the ethylene-vinyl acetate copolymer. The photovoltaic module manufactured in Comparative Example 3 is schematically shown in Fig.

Comparative Example 4

An encapsulant and a photovoltaic module having the same structure were prepared in the same manner as in Example 1, except that the thickness of the second layer including glass fibers was changed to 1,000 탆.

Comparative Example 5

An encapsulant and a photovoltaic module having the same structure were prepared in the same manner as in Example 1 except that the thickness of the second layer including glass fibers was changed to 10 탆.

The measurement results of the above Examples and Comparative Examples are shown in Table 1 below.

division Example Comparative Example One 2 One 2 3 4 5 Flammability measurement
(Unit: second) 180 170 110 105 125 230 115 Adhesive strength measurement
(Unit: kgf / 10mm) 3.3 3.7 5.9 7.0 3.5 0.1 5.0 Appearance evaluation Good Good Good Good Bad Good Good

As shown in Table 1, the sealing material of the present application includes a layer containing glass fibers to ensure excellent flame retardancy, and is excellent in adhesion of the layer containing the glass fibers of the sealing material to the backsheet It was confirmed that it is possible to secure an adhesive force and to exhibit a good appearance when manufactured by a photovoltaic module.

10: First layer
11, 13: a first layer comprising an ethylene-vinyl acetate copolymer
12: A first layer comprising an ethylene-alpha olefin copolymer
14: First layer comprising ethylene-vinyl acetate and inorganic particles
20: Second layer
30: Front sealing layer
40: photovoltaic cell
50: backside sealing layer
100: seal layer
200: front substrate
300: encapsulant
400: back sheet

Claims

A first layer comprising an ethylenic copolymer; And
And a second layer comprising glass fibers in an amount of more than 10 mu m and less than 1,000 mu m.

The encapsulating layer according to claim 1, wherein the ethylenic copolymer is an ethylene-vinyl acetate copolymer or an ethylene-alpha olefin copolymer.

The encapsulating layer according to claim 1, wherein the second layer does not contain flame-retardant inorganic particles.

Front encapsulation layer;
At least two photovoltaic cells spaced apart from each other on at least one surface of the front seal layer; And
And a backside sealing layer sealing the photovoltaic cell,
Wherein the backside sealing layer comprises the sealing layer according to claim 1.

The encapsulating material according to claim 1, wherein the whole encapsulating layer comprises an ethylenic copolymer.

The encapsulant according to claim 1, wherein the ethylenic copolymer is an ethylene-vinyl acetate copolymer or an ethylene-alpha olefin copolymer.

The encapsulating material according to claim 1, wherein the back side encapsulating layer is a film or a sheet.

The encapsulating material according to claim 1, which satisfies the following formula (1)
[Equation 1]
X ≥ 0.5 kgf / 10 mm
X represents the adhesive force when the sealing material is peeled off at a peeling angle of 180 degrees and a peeling rate of 300 mm / min after attaching the sealing material to the back sheet at 160 캜 for 17 minutes in a width of 10 mm.

The bag material according to claim 8, wherein X is 3.0 kgf / 10 mm or more.

The encapsulating material according to claim 1, which satisfies the following formula (2)
[Equation 2]
Y? 150
In the formula (2), Y represents the time required for the 75 mm length portion of the specimen to ignite after attaching the encapsulant to the back sheet at 160 캜 for 17 minutes at 12.5 mm x 125 mm (width x length) (Seconds).

A first layer comprising an ethylenic copolymer and a second layer comprising glass fibers to form a back side encapsulation layer.

12. The method of manufacturing a sealing material according to claim 11, wherein the step of fabricating the back side sealing layer is performed by coating the first layer or the second layer.

A front substrate;
Back sheet; And
And an encapsulant according to claim 3 existing between the front substrate and the back sheet.

14. The photovoltaic module according to claim 13, wherein the second layer of the back side sealing layer included in the sealing material and the back sheet are attached.