TW201526269A - Back surface protection sheet for solar battery module and manufacturing method thereof - Google Patents

Abstract

A back protective sheet for a solar cell module, which is integrated with a front panel, a solar cell component, and a sealing material to form a back protective sheet for a solar cell module of a solar cell module, which is characterized in that it has a connection with a sealing material. The resin layer of the surface is composed of a resin composition containing a nucleating agent, and the surface of the resin layer that is in contact with the sealing material has a concavo-convex structure having a reflective function.

Description

Back surface protection sheet for solar battery module and manufacturing method thereof

The present invention relates to a back protective sheet for a solar cell module in which a plurality of solar cell elements are enclosed, and more particularly to a back protective sheet for a solar cell module which can improve photoelectric conversion efficiency.

In recent years, due to the improvement of environmental awareness, solar cell power generation systems equipped with solar cell modules have attracted attention as one of the means of generating electricity using clean energy. The solar cell module is provided with a plurality of plate-shaped solar cell elements, and these solar cell elements are sandwiched by a synthetic resin such as an ethylene-vinyl acetate copolymer called a sealing material, and the glass is overlapped on the side irradiated with sunlight. In the front panel, a back surface protective sheet for a solar cell module (hereinafter also referred to simply as a back surface protective sheet) having weather resistance and moisture resistance is laminated on the opposite side, and integrally formed by a vacuum heating lamination method or the like.

Under such circumstances, in the development of solar cell modules, it is necessary to efficiently convert the solar light energy incident on the solar cell module into electric energy, that is, how to improve the photoelectric conversion efficiency becomes a major issue, not only the solar cell components, Even the back protective sheet has been proposed for various improvements.

In Japanese Patent Laid-Open Publication No. 2010-123720, A solar cell module having a front panel and a solar cell element, a sealing material, and a back surface protective sheet is formed, and a back surface protective sheet having a reflective structure of a reflective function is formed on a surface side of the back surface protective sheet that is in contact with the sealing material. Here, as a method of directly forming the uneven structure on the back surface protective sheet, a pressing method using a metal mold, a casting method, an extrusion molding method, an injection molding method, and the like are exemplified.

However, even if the transfer of the concavo-convex structure is performed on the surface of the back surface protective sheet by a press method, a casting method, an extrusion molding method, or an injection molding method using a metal mold, the uneven structure transferred during the cooling and solidification of the synthetic resin is alleviated, and it is impossible to The shape of the surface is transferred with high precision, and the shape of the surface of the back surface protective sheet, in particular, near the top of the uneven structure, becomes gentle (slope), and there is a problem that sunlight cannot be effectively utilized.

In addition, when the back surface protective sheet having the desired uneven structure is obtained, and the back surface protective sheet and the sealing material are bonded to the ethylene-vinyl acetate copolymer by vacuum heating, the surface of the back surface protective sheet is formed. The uneven structure is flattened and the problem of achieving the desired purpose cannot be achieved.

The present invention has been made in view of the above-described problems, and it is an object of the invention to provide a back surface protective sheet having a high-reflection efficiency by transferring a concave-convex structure having a reflective function to a surface that is in contact with a sealing material with high precision.

The inventor of the case conducted a sharp review. As a result, it was found that the resin layer having the surface in contact with the sealing material of the back surface protective sheet is composed of a resin composition containing a nucleating agent, and the surface which is in contact with the sealing material of the resin layer is provided with a concave and convex function having a reflective function. The back surface protective sheet of the structure can solve the above problems, and the present invention has been completed.

According to the invention, provided

[1] A back protective sheet for a solar cell module, which is integrated with a front panel, a solar cell element, and a sealing material to form a back protective sheet for a solar cell module of a solar cell module, which is characterized in that it has a sealing material. The resin layer of the contact surface is composed of a resin composition containing a nucleating agent, and the surface of the resin layer that is in contact with the sealing material has a concavo-convex structure having a reflective function.

The invention further provides

[2] The back protective sheet for a solar cell module according to [1], wherein the resin composition containing the nucleating agent has a difference between the endothermic peak temperature Tm at the temperature rise measured by DSC and the exothermic peak temperature Tc at the time of temperature drop Δ The Tmc is 40 ° C or less.

[3] The back protective sheet for a solar cell module according to [1] or [2], wherein the resin constituting the back protective sheet for the solar cell module has a melting point of 150 ° C or higher.

[4] The back protective sheet for a solar cell module according to [1] or [2] wherein the resin composition containing the nucleating agent is composed of a polypropylene resin and a phosphate metal nucleating agent.

[5] A method for manufacturing a back protective sheet for a solar cell module, A method of manufacturing a back surface protective sheet for a solar cell module in which a solar cell module is integrated with a front panel, a solar cell element, and a sealing material, and is characterized in that a resin for forming a back surface protective sheet from a resin composition containing a nucleating agent a layer, and then a resin layer in a molten state or a softened state is transferred to the surface of the resin layer by pressure contact with an embossing roll engraved with a concave-convex structure for imparting a function of reflecting light to form a contact with the sealing material. The face.

[6] A solar cell module, which is a solar cell module in which a front panel, a solar cell component, a sealing material and a back protective sheet are sequentially laminated, wherein the back protective sheet has a nucleating agent. And a resin layer having a reflective uneven surface, and the reflective uneven surface is in contact with the sealing material.

In the back surface protective sheet of the present invention, since the uneven structure having the reflective function on the surface of the sheet is accurately transferred, the solar cell module using the back surface protective sheet further improves the photoelectric conversion efficiency. Further, according to the production method of the present invention, the above-mentioned back surface protective sheet can be produced by a simple method.

1‧‧‧Solar battery module

11‧‧‧Back protector

12‧‧‧ Sealing material

13‧‧‧Solar battery components

14‧‧‧ front panel

Fig. 1 is a schematic partial cross-sectional view showing a solar cell module 1 using a back protective sheet of the present invention.

Fig. 2 is a schematic perspective view showing a concavo-convex structure having a reflective function of the back surface protective sheet of the present invention.

Fig. 3 is an observation image of the uneven structure of the back surface protective sheet members produced in Examples 1 to 3 and Comparative Example 1 according to a laser microscope.

Hereinafter, the back protective sheet of the present invention will be described in detail.

Fig. 1 is a schematic partial cross-sectional view showing a solar cell module 1 using a back protective sheet of the present invention. The solar cell module 1 has a back surface protective sheet 11, a sealing material 12, a solar cell element 13, and a front panel 14. The sunlight L1 is incident on the front panel, and most of the sunlight L2 is incident on the surface of the solar cell element. On the other hand, the sunlight L3 between the solar cell elements is reflected by the back surface protection sheet 11 having the reflective function as the sunlight L4, and the front panel is reflected as the sunlight L5 and is incident on the solar cell element, and the sunlight can be Transformed into electrical energy. The back surface protective sheet 11 is provided with a resin layer including a concave-convex surface having a light-reflecting property of the nucleating agent, and the light-reflecting uneven surface constitutes one surface of the back surface protective sheet 11. The solar cell module 1 is configured by integrating the back surface protective sheet 11 with the sealing material 12, the solar cell element 13, and the front panel 14 in a state where the reflective uneven surface is in contact with the sealing material 12. Since the resin layer is composed of a resin composition containing a nucleating agent, the uneven structure of the light-reflecting surface of the resin layer is formed with high precision. Thereby, the solar cell module 1 using the back surface protective sheet 11 further improves the photoelectric conversion efficiency.

The back protective sheet of the present invention may also be composed only of a resin layer The single layer structure may be a multilayer structure in which a layer having other functions is laminated on the resin layer. Further, the back surface protective sheet may be provided with a gas barrier film in which a metal or an inorganic oxide is vapor-deposited in order to impart gas barrier properties.

Examples of the resin constituting the resin composition containing the nucleating agent include PBT (polybutylene terephthalate), PET (polyethylene terephthalate), and PEN (polyethylene naphthalate). Synthetic resin materials such as ester), PA (polyamide), and PP (polypropylene).

Further, in the case where the back protective sheet of the present invention has a single layer structure or a multilayer structure, the melting point of the resin constituting each layer is preferably 150 ° C or higher. By setting the melting point of the resin to 150 ° C or higher, it is possible to prevent melting and elution of the resin in the vacuum heating lamination step during assembly of the solar cell module.

Examples of the nucleating agent include benzoic acid metal salts such as pt-butyl benzoic acid aluminum and sodium benzoate, sodium bis(2,4-di-t-butylphenyl)phosphate, and methine bis. Aromatic phosphate metal salt such as sodium (2,4-di-t-butylphenyl)phosphate or bis [methine bis(2,4-di-t-butylphenyl)phosphate]hydroxyaluminum And a mixture of an aromatic phosphate metal salt and an alkali metal compound, dibenzylidene sorbitol, bis (methyl dibenzylidene) sorbitol, bis (dimethyl dibenzylidene sorbitol), etc. In addition to an organic nucleating agent such as a fork sorbitol, an amino acid metal salt or a terpine acid metal salt, an inorganic nucleating agent such as talc, clay or calcium carbonate may be mentioned. The amount of the nucleating agent to be added is preferably 0.05 to 1.0 part by weight, more preferably 0.1 to 0.5 part by weight, per 100 parts by weight of the resin constituting the resin layer. 50% particle size of the nucleating agent The median diameter is preferably in the range of 2 to 20 μm, more preferably in the range of 3 to 10 μm.

The resin composition constituting the resin layer is formed of a polypropylene resin and phosphoric acid from the viewpoint of being able to be accurately formed on the surface of the resin layer by an uneven structure for imparting a reflective function to a printing plate such as an embossing roll. The ester metal salt-based nucleating agent is particularly preferred.

The resin composition containing the nucleating agent can be more precise by the difference ΔTmc between the endothermic peak temperature Tm at the temperature rise of the DSC measurement (fine scanning calorimetry) and the exothermic peak temperature Tc at the time of the temperature drop of 40° C. or less. It is preferable to transfer the surface shape of the printing plate such as the embossing roll to the uneven structure, and to reduce the uneven structure of the transfer when the resin composition is cooled and solidified, and to obtain the desired uneven structure easily.

Thus, the resin composition having ΔTmc of 40 ° C or less can more faithfully transfer/reproduce the surface shape of the printing plate such as an embossing roll, and it is presumed to be caused by the following mechanism. In other words, when the thermoplastic resin is in a molten state and is cooled by a printing plate such as an embossing roll, the volume is contracted by cooling, but the resin composition having a small ΔTmc is rapidly crystallized after cooling and solidification. Therefore, the volume shrinkage due to cooling is relatively small compared to the resin composition which is slow in crystallization.

Further, the back surface protective sheet is preferably made to improve the light reflectivity of the surface in contact with the sealing material. As a specific means, a method of performing metal deposition on the surface of the back surface protective sheet that is in contact with the sealing material, and a method of coloring the resin layer of the back surface protective sheet to white may be mentioned. Among them, the method of coloring the resin layer to white is simple, and the cost increase can be suppressed to the minimum. Degree is better. Examples of the white pigment to be used herein include titanium oxide, zinc oxide, and aluminum oxide. Among them, titanium oxide is preferred because it has a high refractive index and excellent dispersibility in a synthetic resin. The blending amount of the white pigment is preferably 5 to 50 parts by weight based on 100 parts by weight of the resin constituting the resin layer.

The uneven structure on the surface of the resin layer may have a periodic structure and may be indefinite. Further, the height of the convex portion of the uneven structure is preferably 50 μm or less, and more preferably 40 μm or less. When the height is 50 μm or less, the transfer property of the surface of the printing plate such as an embossing roll to the resin layer of the back surface protective sheet is good, and the tip end portion of the convex portion is not damaged. On the other hand, the height of the convex portion of the uneven structure is preferably 5 μm or more, and more preferably 10 μm or more. When the height is 5 μm or more, sunlight can be effectively utilized. Moreover, the "height of the convex portion of the uneven structure" means the height of the apex of the convex portion based on the valley portion.

Further, in the present invention, as shown in FIG. 2, the uneven structure of the reflective resin layer has an inclination angle θ of 15 degrees or more and less than 45 degrees because the reflected light from the back surface protection sheet can be made larger than the critical angle toward the front panel. It is preferable that the angle is incident, and the reflected light from the back surface protective sheet can be efficiently enclosed in the solar cell module.

In addition, the thickness of the back surface protective sheet is from 100 μm to 600 μm, and it is possible to achieve a roll-up of the back surface protective sheet by preventing the moisture from being transmitted into the solar cell module, and it is excellent in handling properties such as wrinkles. Preferably.

The back protective sheet of the present invention can be installed, for example, by The extruder of the flat mold is supplied with a resin composition containing a nucleating agent, and the resin composition in a molten state or a softened state is extruded in a sheet shape from a flat mold, so that the molten sheet in a molten state or a softened state is brought into pressure contact. It is manufactured by simultaneously drawing and pulling an embossing roll which is printed with a concave-convex structure for imparting a reflective function. Further, in the case of producing the back surface protective sheet having the above-described multilayer structure, a method of collectively pressing out by a flat mold to which a plurality of extruders are attached can be preferably used.

[Examples]

Hereinafter, the present invention will be described in more detail based on the examples, but the present invention is not limited by these examples.

[Example 1]

Using a single-layer film forming apparatus equipped with a flat mold, 100 parts by weight of a bulk polypropylene (melting point: 164 ° C), and a nucleating agent (manufactured by Adeka Co., Ltd.: aromatic phosphate metal salt) 0.1 part by weight of a resin The composition was extruded into a sheet shape, and was pressed into contact with an engraved embossing roll which was applied to provide a concavo-convex structure of a positive square pyramid having a side of 78 μm, a height of 27 μm, and an inclination angle of 35 degrees, and was simultaneously drawn and manufactured on the surface. A single-layer back protective sheet having a convex structure of a regular square pyramid and having a thickness of 120 μm.

[Example 2]

A back surface protective sheet having a thickness of 120 μm was produced in the same manner as in Example 1 except that the amount of the nucleating agent was 0.2 parts by weight.

[Example 3]

A back surface protective sheet having a thickness of 120 μm was produced in the same manner as in Example 1 except that the amount of the nucleating agent was 0.3 parts by weight.

[Comparative Example 1]

A back protective sheet having a thickness of 120 μm was produced in the same manner as in Example 1 except that the nucleating agent was not blended.

The endothermic peak temperature Tm at the time of temperature rise of the back surface protective sheets obtained in Examples 1 to 3 and Comparative Example 1 and the exothermic peak temperature Tc at the time of temperature drop were measured, and the difference ΔTmc was obtained. That is, the endothermic peak temperature Tm at which the measurement sample was heated from 30 ° C to 250 ° C at a temperature increase rate of 10 ° C/min was measured using a differential scanning calorimeter (DSC), and the measurement sample was cooled at a rate of 10 ° C/min. The exothermic peak temperature Tc when cooled from 250 ° C to 0 ° C. The measurement results are shown in Table 1.

Moreover, the uneven structure of the surface of the back surface protective sheets obtained in Examples 1-3 and Comparative Example 1 was observed using a laser microscope (Confocal microscope C130 manufactured by LaserTech Co., Ltd.). This observed image is shown in Figure 3. The height (embossing height) of the convex portion of the uneven structure was measured by observing the image. The results are shown in Table 1.

As is apparent from Tables 1 and 3, the back surface protective sheets of Examples 1 to 3 composed of a resin composition containing a nucleating agent were transferred to a specific uneven structure with high precision. On the other hand, the uneven structure of the back surface protective sheet of Comparative Example 1 which was transferred to the resin composition containing no nucleating agent was gentle in shape in the vicinity of the top, and the uneven structure was obtained in comparison with Examples 1 to 3. The accuracy is very low.

[Example 4]

Using a single-layer film forming apparatus equipped with a flat mold, 100 parts by weight of a bulk polypropylene (melting point: 164 ° C), 25 parts by weight of titanium oxide, and a nucleating agent (manufactured by ADEKA Co., Ltd.: aromatic phosphate metal salt system) 0.1 part by weight of the resin composition was extruded into a sheet shape, and pressed into contact with an engraving which was provided with a concavo-convex structure having a pitch of 125 μm, a height of 20 μm, and an inclination angle of 22 degrees. The embossing roll was simultaneously pulled, and a single-layer resin sheet having a thickness of 120 μm having a concavo-convex structure of a two-sided triangular pyramid shape was produced. Next, a polyethylene terephthalate film having a thickness of 190 μm (melting point: 260 ° C) and a thickness of 50 μm of polybutylene terephthalate film were sequentially deposited on the resin sheet by a dry lamination method. (melting point 230 ° C) A three-layer back protective sheet having a thickness of 360 μm was obtained.

[Comparative Example 2]

A resin sheet having a thickness of 120 μm was produced in the same manner as in Example 4 except that the nucleating agent was not blended. Next, in the same manner as in Example 4, a polyethylene terephthalate film was sequentially deposited on the resin sheet by a dry lamination method, and a polybutylene terephthalate film was used to obtain a back layer of three layers having a thickness of 360 μm. sheet.

The output improvement effect of the solar module assembled using the back surface protective sheets obtained in Example 4 and Comparative Example 2 was evaluated. The steps are as follows.

(1) Measurement of the output (Pmax) of the solar cell element ‧ ‧ The solar cell element (the half of the 6-inch element is cut in half) is placed up and down, and the solar cell elements are arranged to have a gap of 3.0 mm. Next, the simulated solar light was irradiated in an atmosphere of 25 ° C by a solar simulator (NCT-180AA-M manufactured by NPC Corporation), and the output (Pmax) of the solar cell element was measured.

(2) Assembly of solar cell modules ‧ ‧ tiered front panel (glass), sealing material (ethylene-vinyl acetate copolymer), solar cell components (1) wiring, sealing material (ethylene - A vinyl acetate copolymer and a back protective sheet were integrated by a vacuum heating lamination method to produce a solar cell module.

(3) Measurement of the output of the solar cell module (Pmax) ‧‧‧ For the solar cell module assembled in (2), the atmosphere at 25 °C by the solar simulator (NCT-180AA-M manufactured by NPC) Lower illumination simulated sun Light, measure the output (Pmax) of the solar cell module.

(4) Evaluation of the output improvement effect ‧ The evaluation of the output (Pmax) of the solar cell module measured in (3) is evaluated based on the output (Pmax) of the solar cell element measured in (1) ( %).

The output improvement effect of the solar cell module produced using the back surface protective sheets obtained in Example 4 and Comparative Example 2 was evaluated by the above procedure. The results are shown in Table 2.

As is clear from Table 2, the resin layer having the surface in contact with the sealing material is composed of a resin composition containing a nucleating agent, and the surface of the resin layer that is in contact with the sealing material is provided with a concave-convex structure having a reflective function. The solar cell module fabricated by the back surface protective sheet of Example 4 exhibited a better output improvement effect than the solar cell module fabricated using the back surface protective sheet of Comparative Example 2.

[Industrial use possibility]

As described above, the back surface protective sheet of the present invention comprises a resin layer having a light-reflecting uneven surface including a nucleating agent, so that the back surface protective sheet is integrated with the front panel, the solar cell element, and the sealing material. The obtained solar cell module can efficiently convert incident solar energy into electric energy. Further, according to the manufacturing method of the present invention, The aforementioned back protective sheet can be easily manufactured. As described above, the back surface protective sheet of the present invention is useful in a solar cell power generation system which has been attracting attention in recent years by using the solar cell module and its manufacturing method, and is very advantageous for industrial applications.

Claims (6)

A back protective sheet for a solar cell module, which is integrated with a front panel, a solar cell component, and a sealing material to form a back protective sheet for a solar cell module of a solar cell module, which is characterized in that it has a connection with a sealing material. The resin layer of the surface is composed of a resin composition containing a nucleating agent, and the surface of the resin layer that is in contact with the sealing material has a concavo-convex structure having a reflective function. The back surface protective sheet for a solar cell module according to the first aspect of the patent application, wherein the resin composition containing the nucleating agent has a difference between the endothermic peak temperature Tm at the temperature rise measured by DSC and the exothermic peak temperature Tc at the time of cooling. The Tmc is 40 ° C or less. The back surface protective sheet for a solar cell module according to claim 1 or 2, wherein the resin constituting the back surface protective sheet for a solar cell module has a melting point of 150 ° C or higher. The back surface protective sheet for a solar cell module according to claim 1 or 2, wherein the resin composition containing the nucleating agent is composed of a polypropylene resin and a phosphate metal salt nucleating agent. A method for manufacturing a back surface protection sheet for a solar cell module, which is a method for manufacturing a solar cell module back surface protection sheet which is integrated with a front panel, a solar cell element, and a sealing material, and is characterized in that: The resin composition containing the nucleating agent forms a resin layer of the back surface protective sheet, and then the resin layer in a molten state or a softened state is pressed into contact with an embossing roll having an uneven structure for imparting a function for imparting a reflective function. concave The convex structure is transferred to the surface of the resin layer to form a face that is in contact with the sealing material. A solar cell module is a solar cell module in which a front panel, a solar cell component, a sealing material and a back protective sheet are sequentially laminated, and the solar cell module is characterized in that: the back protective sheet has a nucleating agent and is reflective The resin layer of the uneven surface, the reflective uneven surface is in contact with the sealing material.