KR101981331B1 - Encapsulant for solar cells and solar cell module comprising the same - Google Patents

Abstract

An embodiment of the present invention relates to an encapsulant for a solar cell and a solar cell module comprising the encapsulant. The encapsulant for solar cell is excellent in moisture resistance and adsorbs acetic acid generated from an ethylene-vinyl acetate copolymer, so that durability is excellent. Therefore, the solar battery module including the sealing member for the solar cell can minimize the output drop even when exposed to the outside for a long period of time.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an encapsulant for a solar cell and a solar cell module including the encapsulant,

An embodiment of the present invention relates to a solar cell encapsulant which is excellent in durability and moisture resistance and can minimize a power output of the solar cell, and a solar cell module including the encapsulant.

Ethylene-vinyl acetate copolymers have been widely used as encapsulants for solar cell modules. However, the ethylene-vinyl acetate copolymer has a problem in that acetic acid is generated due to hydrolytic action when exposed to the outside for a long time. Particularly, the acetic acid generated at this time has a problem of shortening the lifetime of the solar cell module by corroding the electrode of the solar cell module. Therefore, many researchers have made great efforts to control the acetic acid production of ethylene-vinyl acetate copolymer.

As a most fundamental solution, a method of using a polyolefin encapsulant as an encapsulant for a solar cell module instead of an ethylene-vinyl acetate copolymer has been proposed (Korean Patent Publication No. 2009-0096487). However, the polyolefin is less heat-resistant than the ethylene-vinyl acetate copolymer and is difficult to be commercially applied due to the high price.

Japanese Patent No. 5819159 and No. 5820132 disclose a method of mixing an ethylene-vinyl acetate copolymer and an ethylene methacrylic acid copolymer. However, when the effect of inhibiting the formation of acetic acid is not clear and two or more kinds of resins are mixed Which can cause difficulties in the process.

Further, Japanese Patent No. 4863812 discloses a method of applying a carbodiimide compound as a dehydration agent in order to suppress the generation of acetic acid in an ethylene-vinyl acetate copolymer. However, there is a problem that the moisture release of the above-mentioned moisture causes yellowing of the sealing material.

Korean Patent Publication No. 2009-0096487 Japanese Patent No. 5819159 Japanese Patent No. 5820132 Japanese Patent No. 4863812

Accordingly, one embodiment provides a solar cell encapsulant capable of suppressing the generation of acetic acid in the ethylene-vinyl acetate copolymer and having excellent durability, thereby minimizing the power output and shortening the lifetime of the solar cell, and a solar cell module I want to.

To achieve the above object,

Ethylene-vinyl acetate copolymer and magnesium oxide,

Wherein the magnesium oxide is contained in an amount of 0.001 to 0.20 parts by weight based on 100 parts by weight of the ethylene-vinyl acetate copolymer and has a specific surface area of 50 to 200 m < 2 > / g.

In another embodiment,

A first encapsulant sheet, at least one solar battery cell to which electrodes are connected, a second encapsulant sheet, and a back sheet in this order,

Wherein at least one of the first encapsulation material sheet and the second encapsulation material sheet comprises an ethylene-vinyl acetate copolymer and magnesium oxide,

Wherein the magnesium oxide is contained in an amount of 0.001 to 0.20 parts by weight based on 100 parts by weight of the ethylene-vinyl acetate copolymer, and has a specific surface area of 50 to 200 m < 2 > / g.

In another embodiment,

(1) preparing a master batch by mixing an ethylene-vinyl acetate copolymer and magnesium oxide;

(2) mixing the master batch and the ethylene-vinyl acetate copolymer to prepare an encapsulating material composition; And

(3) melt-extruding the encapsulation material composition,

Wherein the sealing material composition contains 0.001 to 0.20 parts by weight of magnesium oxide per 100 parts by weight of the ethylene-vinyl acetate copolymer,

Wherein the magnesium oxide has a specific surface area of 50 to 200 m < 2 > / g.

The encapsulant for solar cell according to the embodiment is excellent in moisture resistance and absorbs acetic acid generated from the ethylene-vinyl acetate copolymer, and thus has excellent durability. Therefore, the solar battery module including the sealing member for the solar cell can minimize the output drop even when exposed to the outside for a long period of time.

Figs. 1 and 2 schematically show configurations (respectively an exploded view and a coupled view) of a solar cell module according to an embodiment including a solar cell and an encapsulant sheet.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail. The embodiments are not limited to what is described below, but may be modified into various forms as long as the gist of the invention is not changed.

In the context of the present invention, where each film, window, panel, or layer is described as being "on" or "under" each film, window, panel, on " and " under " include all that is formed either "directly" or "indirectly" through "other elements". In addition, the upper and lower standards of each component are described with reference to the drawings. The size of each component in the drawings may be exaggerated for the sake of explanation and does not mean the size actually applied. In addition, like reference numerals refer to like elements throughout the specification.

In addition, " comprising " in this specification means that other elements may be further included unless otherwise specified.

In addition, all numbers and expressions indicating amounts of ingredients, reaction conditions, and the like described in this specification are to be understood as being modified in all instances by the term " about " unless otherwise specified.

For solar cells Encapsulant

One embodiment includes an ethylene-vinyl acetate copolymer and magnesium oxide,

Wherein the magnesium oxide is contained in an amount of 0.001 to 0.20 parts by weight based on 100 parts by weight of the ethylene-vinyl acetate copolymer and has a specific surface area of 50 to 200 m < 2 > / g.

Ethylene-vinyl acetate copolymer

The ethylene-vinyl acetate copolymer may comprise 20 to 35 weight percent vinyl acetate based on the total weight of the copolymer. Specifically, the ethylene-vinyl acetate copolymer may comprise 26 to 33 weight percent vinyl acetate based on the total weight of the copolymer. When the content of vinyl acetate is within the above range, it has an excellent sheet formability and an excellent effect of protecting a cell with a sealing material for a solar cell.

The ethylene-vinyl acetate copolymer may have a melting folw rate (MFR) of 5 to 30 g / 10 min at 190 ° C based on 2.16 kg. Specifically, the ethylene-vinyl acetate copolymer may have a melt flow index (MFR) of 10 to 20 g / 10 min based on 2.16 kg at 190 ° C. When the melt flow index of the ethylene-vinyl acetate copolymer is within the above range, the flowability is low and the copolymer is not easily extruded and the flowability is too high, so that the copolymer flows out in the lamination process, The sheet can be stably formed.

The ethylene-vinyl acetate copolymer may have a weight average molecular weight of 10,000 to 100,000 g / mol. Specifically, the copolymer may have a weight average molecular weight of 20,000 to 60,000 g / mol.

Magnesium oxide

The magnesium oxide is contained in an amount of 0.001 to 0.20 parts by weight based on 100 parts by weight of the ethylene-vinyl acetate copolymer. Specifically, the magnesium oxide may be contained in an amount of 0.005 to 0.10 parts by weight, 0.009 to 0.07 parts by weight, 0.01 to 0.20 parts by weight, or 0.01 to 0.15 parts by weight based on 100 parts by weight of the ethylene-vinyl acetate copolymer. When the content of magnesium oxide is within the above range, it is dispersed evenly in the encapsulating material to facilitate the adsorption of acetic acid, the light transmittance of the encapsulant is lowered, and the output of the solar cell module is lowered, and the crosslinking reaction of the ethylene- So that the problem of deterioration of the degree of crosslinking of the encapsulating material can be prevented.

The magnesium oxide has a specific surface area of 50 to 200 m < 2 > / g. Specifically, the magnesium oxide may have a specific surface area of 70 to 200 m 2 / g, 90 to 200 m 2 / g, or 100 to 200 m 2 / g. If the specific surface area of the magnesium oxide is within the above range, the magnesium oxide may have low reactivity and lower acetic acid adsorption performance, and a problem that the crosslinking of the ethylene-vinyl acetate copolymer It is possible to prevent the problem that the crosslinking degree of the sealing material is lowered by delaying the reaction. Particularly, as described above, since magnesium oxide of the embodiment has a large specific surface area, the desired acetic acid adsorption performance can be achieved even when a small amount is used. Accordingly, it is possible to further improve the durability of the solar cell encapsulant manufactured by suppressing the generation of acetic acid while reducing side effects that may occur due to excessive use of magnesium oxide.

In the case of a substance which adsorbs an acid other than the above-mentioned magnesium oxide, it also has a property of adsorbing most of the water. For example, zeolite or silica has the property of adsorbing an acid like magnesium oxide, and when used in an encapsulating material for a solar cell, it can exhibit similar acetic acid adsorption effect, but it has a disadvantage of adsorbing moisture as well as acetic acid. Therefore, when zeolite or silica is used instead of magnesium oxide for the encapsulation material, the encapsulation material adsorbs moisture under harsh conditions, resulting in a problem that the volume resistivity of the encapsulation material is reduced and the wet leakage resistance is lowered. On the other hand, in the case of magnesium oxide, the problem does not occur even under severe conditions because moisture adsorption does not occur.

The magnesium oxide may have an average particle diameter of 1 to 20 mu m. Specifically, the magnesium oxide may have an average particle diameter of 2 to 10 mu m.

The magnesium oxide may have an appropriate particle size distribution. For example, the magnesium oxide may have a content of particles having a particle size smaller by 2.5 占 퐉 or more than the average particle size in an amount of 5 to 15% by weight based on the total weight. The magnesium oxide may have a content of particles having a particle diameter larger than the average particle diameter of 6.5 mu m or more by 5 to 15 wt% based on the total weight. When the particle size distribution as described above is provided, the durability of the encapsulating material for a solar cell to be manufactured can be improved.

Cross-linking agent

The solar cell encapsulant may include an organic peroxide as a crosslinking agent, and the organic peroxide may improve the weatherability of the solar cell encapsulant.

The crosslinking agent is not particularly limited as long as it is an organic peroxide capable of generating radicals at 100 占 폚 or more, but it is preferable that the crosslinking agent has a half-life of not less than 10 hours and a decomposition temperature of not less than 70 占 폚. The lower half-life temperature means that the reactivity is faster, and the higher the half life temperature, the slower the reactivity.

Specifically, the organic peroxide is selected from the group consisting of 2,5-dimethylhexane, 2,5-dihydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) (T-butylperoxy) butane, 2,2-bis (t-butylperoxy) butane, t-butylperoxy (T-butylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, t-butylperoxybenzoate, benzoyl Peroxides and t-butyl peroxy-2-ethylhexylcarbonate.

The crosslinking agent may be contained in an amount of 5 parts by weight or less based on 100 parts by weight of the ethylene-vinyl acetate copolymer. Specifically, the crosslinking agent may be contained in an amount of 0.3 to 5 parts by weight, or 0.3 to 2 parts by weight based on 100 parts by weight of the ethylene-vinyl acetate copolymer.

Crosslinking aid

The solar cell encapsulant may include a crosslinking aid. The crosslinking assistant enhances the gel fraction of the ethylene-vinyl acetate copolymer and improves the durability of the encapsulating material.

The crosslinking aid may be contained in an amount of 10 parts by weight or less based on 100 parts by weight of the ethylene-vinyl acetate copolymer. Specifically, the crosslinking aid may be contained in an amount of 0.1 to 10 parts by weight, 0.1 to 5 parts by weight, or 0.1 to 3 parts by weight based on 100 parts by weight of the ethylene-vinyl acetate copolymer.

Examples of the crosslinking aid include compounds having three functional groups such as triallyl isocyanurate and triallyl isocyanate, and compounds having one functional group such as an ester.

additive

The solar cell encapsulant may further include an additive selected from the group consisting of a silane coupling agent, a quinone compound, an ultraviolet absorber, an antioxidant, and a discoloration inhibitor.

The silane coupling agent serves to improve the adhesion between the encapsulant and the solar cell. The silane coupling agent may be, for example, γ-chloropropyltrimethoxysilane, vinyltriclorosilane, vinyl-tris- (β-methoxyethoxy) silane, γ-methoxypropyltrimethoxysilane ,? - (3,4-ethoxycyclohexyl) ethyltrimethoxysilane,? -Mercaptopropyltrimethoxysilane, and the like.

The silane coupling agent may be included in an amount of 5 parts by weight or less based on 100 parts by weight of the ethylene-vinyl acetate copolymer. Specifically, the silane coupling agent may be contained in an amount of 0.1 to 5 parts by weight, 0.1 to 3 parts by weight, or 0.1 to 2 parts by weight based on 100 parts by weight of the ethylene-vinyl acetate copolymer.

The quinone-based compound serves to improve the stability of the ethylene-vinyl acetate copolymer. Examples of the quinone compound include hydroquinone, hydroquinone methyl ethyl, p-benzoquinone, methylhydroquinone, and the like. The quinone compound may be contained in an amount of 5 parts by weight or less based on 100 parts by weight of the ethylene-vinyl acetate copolymer. Specifically, the quinone-based compound may be contained in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the ethylene-vinyl acetate copolymer.

Examples of the ultraviolet absorber include benzophenone compounds such as 2-hydroxy-4-octoxybenzophenone and 2-hydroxy-4-methoxy-5-sulfobenzophenone; Benzotriazole systems such as 2- (2'-hydroxy-5-methylphenyl) benzotriazole; And salicylates such as phenyl salicylate and p-t-butylphenyl salicylate.

Examples of the antioxidant include amine-based, phenol-based, and bisphenyl-based antioxidants. Specifically, examples of the antioxidant include t-butyl-p-cresol, bis- (2,2,6,6-tetramethyl-4-piperazyl) sebacate, and the like.

For solar cells Encapsulant

The solar cell encapsulant can be produced by extruding a sealing material composition comprising an ethylene-vinyl acetate copolymer and magnesium oxide into a non-cured or semi-cured sheet.

The solar cell encapsulant is applied to the solar cell module and cured to perform a sealing function. The volume specific resistance and haze of a sealing material for a solar cell to be described later are the physical property values measured after the sealing material for a solar cell is cured.

The solar cell encapsulant may have a volume resistivity of 1 × 10 ¹⁶ to 1 × 10 ¹⁷ Ω · cm measured at a voltage of 25 ° C. and 1,000 V. Specifically, the solar cell encapsulant has a volume resistivity of 1 × 10 ¹⁶ to 5 × 10 ¹⁶ Ω · cm, 1 × 10 ¹⁶ to 4 × 10 ¹⁶ Ω · cm, or 1 × 10 ¹⁶ Ω · cm measured at a voltage of 25 ° C. and 1,000 V, × 10 may be a ¹⁶ to 3 × 10 ¹⁶ Ω · ㎝.

The solar cell encapsulant may have a volume resistivity of 1 × 10 ¹⁵ Ω · cm or more measured at a voltage of 1,000 V after being left at 100% RH and 120 ° C. for 72 hours. Specifically, the solar cell encapsulant may have a volume resistivity of 1 × 10 ¹⁵ to 1 × 10 ¹⁷ Ω · cm measured at a voltage of 1,000 V after left for 72 hours at a relative humidity of 100% and 120 ° C. Especially, When the volume resistivity of the solar cell encapsulant is 1 x 10 < ¹⁵ > OMEGA .cm or less, the wet leakage resistance of the sealing material may be lowered.

However, the encapsulant for a solar cell in one embodiment is excellent in moisture resistance and has a volume resistivity of 1 x 10 < ¹⁵ > OMEGA .cm or more even after 72 hours under the condition of 120 deg. C and a relative humidity of 100% It is effective.

The sealing material for a solar cell is a sample obtained by cutting a sample of 1,000 mm x 200 mm x 0.5 mm (width x length x thickness) into 100 mm x 100 mm (width x length) and measuring an average haze of 2 to 8% , And the standard deviation of the haze of the sample may be 0.1 to 0.5%. Specifically, the solar cell encapsulant was prepared by cutting a sample of 1,000 mm x 200 mm x 0.5 mm (width x length x thickness) into a size of 100 mm x 100 mm (width x length) 8%, 4 to 7%, or 5 to 6%, and the standard deviation of the haze of the sample may be 0.1 to 0.4%, or 0.1 to 0.3%.

The sealing material for a solar cell may have a curing reaction initiation time measured by a rheometer at 150 ° C of 3 minutes or less. Specifically, the sealing material for a solar cell may have a curing reaction initiation time of 1 to 3 minutes measured by a rheometer at 150 ° C.

The solar cell encapsulant may have an average thickness of 200 to 800 탆. Specifically, the solar cell encapsulant may have an average thickness of 300 to 700 탆.

Solar cell module

One embodiment includes a stacked structure in which a transparent protective substrate, a first encapsulating material sheet, at least one solar cell connected to an electrode, a second encapsulating material sheet, and a back sheet are stacked in order,

Wherein at least one of the first encapsulation material sheet and the second encapsulation material sheet comprises an ethylene-vinyl acetate copolymer and magnesium oxide,

Wherein the magnesium oxide is contained in an amount of 0.001 to 0.20 parts by weight based on 100 parts by weight of the ethylene-vinyl acetate copolymer, and has a specific surface area of 50 to 200 m < 2 > / g.

Figs. 1 and 2 show configurations (respectively an exploded view and a coupled view) of a solar cell module according to an embodiment. The solar cell module 10 includes a transparent protective substrate 14, a first encapsulating material sheet 12, at least one solar cell 11 connected to the electrodes, a second encapsulating material sheet 12 ' And at least one of the first encapsulation material sheet 12 and the second encapsulation material sheet 12 'comprises an ethylene-vinyl acetate copolymer and magnesium oxide.

Such a solar cell module 10 may be one produced by laminating the constituent layers including the solar cell 11 and the sealing material sheets 12 and 12 'in order and then processing (heating and pressing) At least one of the first encapsulating material sheet 12 and the second encapsulating material sheet 12 'may be a sealing material for a solar cell as described above.

The solar cell 11, the back sheet 13, and the transparent protective substrate 14 constituting the solar cell module 10 can be appropriately selected and used as those conventionally used. In particular, both the transparent protective substrate and the back sheet may be glass substrates.

The solar cell module may have a power reduction rate of 5% or less after being left at a relative humidity of 85% and 85 캜 for 3,000 hours. Specifically, the solar cell module may have a power decrease rate of 0.1 to 5%, 1 to 5%, 2 to 5%, or 2 to 4.8% after 3,000 hours of relative humidity at 85% and 85 ° C.

For solar cells Encapsulant  Manufacturing method

In yet another embodiment,

(1) preparing a master batch by mixing an ethylene-vinyl acetate copolymer and magnesium oxide;

(2) mixing the master batch and the ethylene-vinyl acetate copolymer to prepare an encapsulating material composition; And

(3) melt-extruding the encapsulation material composition,

Wherein the sealing material composition contains 0.001 to 0.20 parts by weight of magnesium oxide per 100 parts by weight of the ethylene-vinyl acetate copolymer,

Wherein the magnesium oxide has a specific surface area of 50 to 200 m < 2 > / g.

Step (1)

In this step, a master batch is prepared by mixing ethylene-vinyl acetate copolymer and magnesium oxide.

The above-mentioned ethylene-vinyl acetate copolymer and magnesium oxide are as described for the encapsulating material for solar cell.

The masterbatch may comprise 0.3 to 5 parts by weight of magnesium oxide based on 100 parts by weight of the ethylene-vinyl acetate copolymer. Specifically, the master batch may contain 0.3 to 4 parts by weight, 0.3 to 3 parts by weight, or 0.4 to 1 part by weight of magnesium oxide based on 100 parts by weight of the ethylene-vinyl acetate copolymer.

Mixing of this step can be carried out at 80 to 160 < 0 > C. Specifically, the mixing of this step can be carried out at 80 to 150 캜, 100 to 140 캜, or 120 to 140 캜.

Step (2)

In this step, the sealant composition may be prepared by mixing the master batch and the ethylene-vinyl acetate copolymer.

The mixing ratio of the master batch and the ethylene-vinyl acetate copolymer may be 1: 5 to 100 by weight. Specifically, the mixing ratio of the master batch and the ethylene-vinyl acetate copolymer may be 1: 5 to 50, 1: 5 to 30, or 1: 5 to 20.

As the content of magnesium oxide contained in the master batch increases, the feeding rate of the ethylene-vinyl acetate copolymer relative to the master batch can be increased. The mixing ratio of the master batch and the ethylene-vinyl acetate copolymer can be controlled by the ratio of the feed rate of the master batch and the ethylene-vinyl acetate copolymer.

Mixing of this step can be carried out at 70 to 120 < 0 > C. Concretely, the mixing of this step may be carried out at 75 to 120 ° C, 75 to 100 ° C, or 75 to 95 ° C.

[ Example ]

Hereinafter, the present invention will be described in detail with reference to examples. However, the following examples are illustrative of the present invention, and the contents of the present invention are not limited by the following examples.

The components used in the following examples and comparative examples are as follows.

Ethylene-vinyl acetate copolymer containing 28% by weight of vinyl acetate, weight average molecular weight of 54,000 g / mol, melt flow index (MFR) of 15 g / 10 min at 190 DEG C and 2.16 kg.

- Crosslinking agent: Luperox TBEC (t-butylperoxy-2-ethylhexyl carbonate) from Akeemaa.

- Crosslinking aid: TAICROS (triallyl isocyanurate) from Ebonics.

Magnesium oxide A: Specific surface area 100 m < 2 > / g.

- Magnesium oxide B: Specific surface area 150 m < 2 > / g.

- Magnesium oxide C: Specific surface area 200 m < 2 > / g.

- Magnesium oxide D: Specific surface area 30 m < 2 > / g.

- Magnesium oxide E: Specific surface area 250 m < 2 > / g.

Example  One. Encapsulant  Produce

0.01 part by weight of magnesium oxide A was compounded with 100 parts by weight of the ethylene-vinyl acetate copolymer to prepare a mixture. Then, 1.0 part by weight of a crosslinking agent and 1.0 part by weight of a crosslinking aid were compounded to prepare an encapsulating material composition.

The encapsulant composition was applied to a T-die extrusion process at 100 占 폚 to prepare an encapsulant having a thickness of 500 占 퐉.

Example  2 to 9 and Comparative Example  1-4.

An encapsulant was prepared in the same manner as in Example 1 except that the kind and content of magnesium oxide were changed as shown in Table 1 below.

Example  10.

At a temperature of 130 ° C, 0.5 part by weight of magnesium oxide B was compounded with respect to 100 parts by weight of the ethylene-vinyl acetate copolymer to prepare a master batch. The master batch and the ethylene-vinyl acetate copolymer were fed in a ratio of 1:10 by weight Lt; RTI ID = 0.0 > 85 C < / RTI > Then, 1.0 part by weight of a crosslinking agent and 1.0 part by weight of a crosslinking aid were added and mixed to prepare a sealant composition.

The encapsulant composition was applied to a T-die extrusion process at 100 占 폚 to prepare an encapsulant having a thickness of 500 占 퐉.

ingredient
(Parts by weight) Ethylene-vinyl acetate copolymer Cross-linking agent Bridging
Supplements Magnesium oxide A Magnesium oxide B Magnesium oxide C Magnesium oxide D Magnesium oxide E Example 1 100 One One 0.01 - - - - Example 2 100 One One 0.05 - - - - Example 3 100 One One 0.2 - - - - Example 4 100 One One - 0.01 - - - Example 5 100 One One - 0.05 - - - Example 6 100 One One - 0.2 - - - Example 7 100 One One - - 0.01 - - Example 8 100 One One - - 0.05 - - Example 9 100 One One - - 0.2 - - Example 10 100 One One - 0.05 - - - Comparative Example 1 100 One One - - - - - Comparative Example 2 100 One One - 0.22 - - - Comparative Example 3 100 One One - - - 0.1 - Comparative Example 4 100 One One - - - - 0.1

Test Example

The properties of the encapsulants of Examples 1 to 10 and Comparative Examples 1 to 4 were measured by the following methods, and the results are shown in Tables 2 to 4 below.

(1) Volumetric resistivity

The sealing material was heated from 1 atm to 150 캜 for 15 minutes by using a vacuum laminator (NPC), and then an initial volume resistivity was measured according to ASTM D257 standard. At this time, a voltage of 1,000 V was applied for 120 seconds.

Thereafter, the volume resistivity change was measured after being left in a pressure cooker test chamber at 120 ° C and 100% relative humidity for 72 hours.

(2) Hayes

The sealing material was cut into a size of 50 mm x 50 mm x 0.5 mm (width x length x thickness) to prepare a sample, and haze was measured at 25 DEG C according to ASTM D1003 standard.

(3) Curing reaction initiation time ( ts1 )

The curing reaction initiation time was measured at 150 ° C using a rheometer.

(4) Manufacture of solar cell module and evaluation of output degradation

(G (glass) to G (glass) structure) lamination in the order of glass / encapsulant / solar cell (manufacturer: JSPV, product name: JSCM3186) / encapsulant / glass. The encapsulant used in Examples 1 to 10 and Comparative Examples 1 to 4 was used.

The size of the solar cell module is 200 mm × 200 mm (width × length) in which one solar cell is inserted. The lamination was carried out using a 50 × 50 laminator manufactured by NPC, and the solar cell module was fabricated at 160 ° C. under a vacuum condition for 5 minutes and 1 minute at 20 minutes.

The initial output value of the solar cell module was measured using a solar simulator corresponding to Class A according to JIS C8912, the light source was measured using a xenon lamp, and the damp heat was measured at 85 ° C and 85% relative humidity for 3,000 hours test), and the output value was measured in the same manner as described above. After the damp heat test, the degraded level was calculated as%.

ingredient Hayes
(%) Volume resistivity
(Ω · cm) 120 캜 and 100% relative humidity Volume resistivity (Ω · cm) after 72 hours 85 ℃ and 85% relative humidity after 3,000 hours
Power drop Comparative Example 1 2.1 5.1 x 10 ¹⁵ 3.2 x 10 ¹⁵ 13% Comparative Example 2 10.5 4.6 x 10 ¹⁵ 2.5 x 10 ¹⁵ 3.2% Example 1 3.7 6.1 x 10 ¹⁵ 1.8 x 10 ¹⁵ 4.1% Example 2 4.8 3.1 x 10 ¹⁵ 2.1 x 10 ¹⁵ 2.9% Example 3 7.6 6.5 x 10 ¹⁵ 2.5 x 10 ¹⁵ 3.4% Example 4 2.9 5.3 x 10 ¹⁵ 1.9 x 10 ¹⁵ 4.7% Example 5 4.1 3.9 x 10 ¹⁵ 2.1 x 10 ¹⁵ 2.9% Example 6 7.8 6.3 x 10 ¹⁵ 3.2 x 10 ¹⁵ 2.9% Example 7 3.2 6.4 x 10 ¹⁵ 2.5 x 10 ¹⁵ 3.5% Example 8 4.9 5.3 x 10 ¹⁵ 1.8 x 10 ¹⁵ 2.9% Example 9 7.6 4.9 x 10 ¹⁵ 2.1 x 10 ¹⁵ 2.5% Example 10 5.6 2.1 x 10 ¹⁶ 3.1 x 10 ¹⁵ -

ingredient ts1 85 ℃, relative humidity 85% 3,000 hours after power degradation Comparative Example 1 2 minutes 50 seconds 13% Comparative Example 2 3 minutes 5 seconds 3.2% Comparative Example 3 2 minutes 51 seconds 7.9% Comparative Example 4 3 minutes 25 seconds 2.3% Example 2 2 minutes 59 seconds 2.9% Example 5 2 minutes 57 seconds 2.9% Example 8 3 minutes 00 seconds 2.9%

Table 2 and Examples 1 to 10 and the encapsulant volume resistivity is 1 × 10 more than ¹⁵ Ω · cm, and a haze value is 5% or less, a pressure cooker, the volume resistivity of 1 × 10 ^15, even after the test, as shown in 3 Ω · cm, and the output drop was less than 5% after being left for 3,000 hours at 85 ° C and 85% relative humidity. In particular, the encapsulant of Example 10 had a very high volume resistivity of 2.1 x 10 < ¹⁶ >

On the other hand, the encapsulant of Comparative Example 1 which did not contain magnesium oxide showed a large output drop after harsh conditions, and the encapsulant of Comparative Example 2 containing an excessive amount of magnesium oxide had a high haze and was not suitable for solar batteries.

(5) Hayes's  Standard Deviation

The sealing material of Example 10 was made into a sample of 1,000 mm x 200 mm x 0.5 mm (width x length x thickness), and the sample was cut into 100 mm x 100 mm (width x length) to prepare 20 samples . Then, the haze of each sample was measured at 25 DEG C according to ASTM D1003 standard, and the average haze and standard deviation of 20 samples were calculated.

Sample Haze (%) Sample Haze (%) One 5.61 11 5.73 2 5.91 12 5.71 3 5.41 13 5.63 4 5.85 14 5.77 5 5.3 15 5.41 6 5.87 16 5.59 7 5.9 17 5.62 8 5.37 18 5.31 9 5.72 19 5.59 10 5.39 20 5.32

The average haze of the samples measured for the encapsulant of Example 10 was 5.6% and the standard deviation of haze was 0.207%, indicating a very uniform distribution.

10: solar cell module 11: solar cell
12: first sealing material sheet 12 ': second sealing material sheet
13: back sheet 14: transparent protective substrate

Claims (13)

Ethylene-vinyl acetate copolymer and magnesium oxide,
Wherein the magnesium oxide is contained in an amount of 0.001 to 0.20 parts by weight based on 100 parts by weight of the ethylene-vinyl acetate copolymer and has a specific surface area of 50 to 200 m < 2 > / g,
Wherein the magnesium oxide has an average particle diameter of 2 to 10 占 퐉 and a magnesium oxide particle diameter of 6.5 占 퐉 or more larger than the average particle diameter is 5 to 15% by weight based on the total weight of the magnesium oxide,
The average haze of the sample cut at 100 mm × 100 mm (width × length) measured at 25 ° C. in a sample of 1,000 mm × 200 mm × 0.5 mm (width × length × thickness) was measured to be 100 mm × 100 mm Is 0.1 to 0.5%.
The method according to claim 1,
Wherein the solar cell encapsulant has a volume resistivity of 1 x 10 ¹⁶ to 1 x 10 ¹⁷ Ω · cm measured at a voltage of 25 ° C and 1,000 V.
The method according to claim 1,
Wherein said solar cell encapsulant has a volume resistivity of 1 × 10 ¹⁵ to 1 × 10 ¹⁷ Ω · cm measured at a voltage of 1,000 V after left for 72 hours at a relative humidity of 100% and 120 ° C.
The method according to claim 1,
Wherein the encapsulating material for a solar cell has a curing reaction initiation time measured by a rheometer at 150 DEG C of not more than 3 minutes.
delete The method according to claim 1,
Wherein said solar cell encapsulant comprises a crosslinking aid,
Wherein the crosslinking aid is contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the ethylene-vinyl acetate copolymer.
The method according to claim 1,
Wherein said solar cell encapsulant comprises an organic peroxide as a crosslinking agent,
Wherein the crosslinking agent is contained in an amount of 0.3 to 5 parts by weight based on 100 parts by weight of the ethylene-vinyl acetate copolymer.
A first encapsulant sheet, at least one solar battery cell to which electrodes are connected, a second encapsulant sheet, and a back sheet in this order,
Wherein at least one of the first encapsulation material sheet and the second encapsulation material sheet comprises an ethylene-vinyl acetate copolymer and magnesium oxide, and a sample of 1,000 mm x 200 mm x 0.5 mm (width x length x thickness) A standard deviation of the haze of the sample is 0.1 to 0.5%, and the average haze of the sample measured at 25 DEG C is 2 to 8%
Wherein the magnesium oxide is contained in an amount of 0.001 to 0.20 parts by weight based on 100 parts by weight of the ethylene-vinyl acetate copolymer and has a specific surface area of 50 to 200 m < 2 > / g,
Wherein the magnesium oxide has an average particle diameter of 2 to 10 占 퐉 and a content of magnesium oxide having a particle diameter larger than the average particle diameter by 6.5 占 퐉 or more is 5 to 15% by weight based on the total weight of the magnesium oxide.
9. The method of claim 8,
Wherein the solar cell module has a power reduction rate of 5% or less after being left at a relative humidity of 85% and 85 캜 for 3,000 hours.
(1) preparing a master batch by mixing an ethylene-vinyl acetate copolymer and magnesium oxide;
(2) mixing the master batch and the ethylene-vinyl acetate copolymer to prepare an encapsulating material composition; And
(3) melt-extruding the encapsulation material composition to produce an encapsulation material,
Wherein the sealing material composition contains 0.001 to 0.20 parts by weight of magnesium oxide per 100 parts by weight of the ethylene-vinyl acetate copolymer,
Wherein the magnesium oxide has a specific surface area of 50 to 200 m < 2 > / g,
Wherein the magnesium oxide has an average particle diameter of 2 to 10 占 퐉 and a magnesium oxide particle diameter of 6.5 占 퐉 or more larger than the average particle diameter is 5 to 15% by weight based on the total weight of the magnesium oxide,
The sealing material was prepared by subjecting a sample cut into a size of 1,000 mm x 200 mm x 0.5 mm (width x length x thickness) to a size of 100 mm x 100 mm (width x length) and measuring an average haze of 2 to 8% Wherein the standard deviation of the haze of the sample is 0.1 to 0.5%.
11. The method of claim 10,
Wherein the masterbatch comprises 0.3 to 5 parts by weight of magnesium oxide based on 100 parts by weight of the ethylene-vinyl acetate copolymer.
11. The method of claim 10,
Wherein the mixing ratio of the master batch to the ethylene-vinyl acetate copolymer is 1: 5 to 100 weight ratio.
11. The method of claim 10,
The mixing of step (1) is carried out at a temperature of from 80 캜 to 160 캜,
Wherein the mixing of step (2) is carried out at a temperature of from 70 캜 to 120 캜.

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