KR101393445B1 - Fabrication method of hetero-junctioned cover glass and its application to photovoltaic modules - Google Patents

Abstract

A heterojuction cover glass of the present invention includes: a cover glass protecting a solar battery by being positioned in a front part where solar light comes in and has a thickness thinner than a cover glass of a normal solar module; and a polymer sheet which reduces an overall weight while reinforcing the cover glass by adhering to the rear side of the cover glass in one integrated body. The heterojunction cover glass of the present invention improves durability, strength, and permeability through a junction with various polymer materials while reducing the thickness of tempered glass (3.2-3.8 mm) which is normally used.

Description

TECHNICAL FIELD [0001] The present invention relates to a heterogeneous junction cover glass, a method of manufacturing the heterogeneous junction cover glass,

The present invention relates to a cover glass for a photovoltaic module, and more particularly to a cover glass for a solar module, which is capable of reducing the thickness of a commonly used tempered glass (3.2 to 3.8 mm) and satisfying improved durability and permeability And a method of manufacturing the same. The present invention also relates to a solar module having light weight and high strength characteristics by having the above-described heterogeneous junction cover glass.

Recently, due to high oil prices and environmental problems, interest in renewable energy is increasing. Among them, solar cells are the areas of greatest interest. Solar cells can be divided into crystalline solar cells using wafers used in semiconductors and thin film solar cells that form semiconductor thin films on substrates such as glass by converting sunlight into electrical energy.

1 is a conceptual view showing a cross section of a conventional crystalline solar module. 1, a conventional solar module 100 includes a solar cell 110 that converts solar energy into electrical energy, a solar cell 110 that is positioned on the front surface of the solar cell 110, A pair of bonding sheets 130 stacked on the top and bottom of the solar cell 110 and a back sheet 130 positioned on the rear surface of the solar cell 110 to protect the solar cell 110. [ sheet, 140).

However, in the case of the crystalline solar module (1620 x 980 mm ² ) constituted as described above, the weight of the crystalline solar module is ~ 20 kg, and thus there are many limitations in applying the module to various fields. The largest portion of the weight of the solar module is the cover glass located on the front side, which occupies approximately 12 to 13 kg in the case of 1620 x 980 mm ² . That is, the weight of the cover glass among the solar modules accounts for 60% or more of the total weight. This is because a cover glass having a thickness of 3.2 mmT or more is used for maintaining the strength of the solar module.

Therefore, research for reducing the weight of the cover glass is absolutely necessary, and at the same time, there is a need for research on various materials that can be lightened while maintaining the weatherability and stability of the solar module compared to the commercialized cover glass.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and it is an object of the present invention to reduce the thickness of generally used tempered glass (3.2 to 3.8 mm) Strength and transmission characteristics, and a method for producing the same.

Another object of the present invention is to provide a solar module having light weight and high strength characteristics by having the above-described heterogeneous junction cover glass.

In order to accomplish the above object, a solar module of the present invention includes: a solar cell for converting light energy of solar light into electric energy; A cover glass disposed on a front surface of the solar cell to receive sunlight to protect the solar cell; A polymer sheet interposed between the cover glass and the solar cell to reinforce the cover glass; A back sheet disposed on a rear surface of the solar cell to protect the solar cell; And a bonding sheet laminated between the polymer sheet and the cover glass and above and below the solar cell to bond the solar cell to the back sheet and to bond the solar cell and the polymer sheet to each other, The polymer sheet and the cover glass in this order are characterized by having a similar transmittance and a mass reduction ratio of 20% in the second half compared with the cover glass having the same thickness.
In addition, according to the present invention, the polymer sheet may be made of polycarbonate (PC), polyether sulfone (PES), polymethyl methacrylate (PMMA), polyimide (PI) (Polyethylene naphthalate).
According to the present invention, the bonding sheet is an ethylene vinyl acetate sheet (EVA sheet) or an olefin sheet (ethylene vinyl acetate sheet).

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The heterogeneous cover glass of the present invention has the advantage of meeting the requirements of improved durability, strength and permeability through bonding with various polymer materials while reducing the thickness of commonly used tempered glass (3.2 to 3.8 mm).

In addition, the solar module of the present invention is advantageous in that it has light weight and high strength characteristics by having the above-described heterogeneous junction cover glass.

1 is a conceptual view showing a cross section of a conventional crystalline solar module,
2 is a conceptual view showing a cross section of a solar module having a heterojunction cover glass according to an embodiment of the present invention,
FIG. 3 is a conceptual view showing a comparative view of the prior art cover glass shown in FIG. 1 and the heterogeneous bonded cover glass of the present invention shown in FIG. 2,
FIG. 4 is a conceptual diagram of a heterojunction cover glass according to an embodiment of the present invention, and photographs of a heterojunction cover glass manufactured by various materials and methods according to the conceptual diagram,
FIG. 5 is a schematic view showing the principle of measurement of transmittance for the heterojunction cover glass of FIG. 4,
FIGS. 6 to 9 are graphs respectively showing transmittances of the heterogeneous bonded cover glass shown in FIG. 4,
FIGS. 10 to 12 are graphs comparing the transmittance and the mass reduction rate between the hetero-junction cover glass shown in FIG. 4 and the conventional cover glass, respectively,
13 is a conceptual view showing a cross section of a solar module having a heterojunction cover glass according to another embodiment of the present invention,
FIG. 14 is a conceptual diagram showing a comparison between the cover glass of the prior art shown in FIG. 1 and the heterojunction cover glass of the present invention shown in FIG.

Best Mode for Carrying Out the Invention Hereinafter, preferred embodiments of a heterogeneous bonded cover glass according to the present invention, a method of manufacturing the same, and a solar module having the same will be described in detail with reference to the accompanying drawings.

FIG. 2 is a conceptual view showing a cross section of a solar cell module having a heterojunction cover glass according to an embodiment of the present invention, FIG. 3 is a view showing the cover glass of the prior art shown in FIG. 1, Fig. 2 is a conceptual diagram showing a comparison of the heterogeneous bonded cover glass of Fig.

2 and 3, the solar module 200 according to this embodiment includes a solar cell 210 for converting the light energy of sunlight into electric energy, A polymer sheet 230 interposed between the cover glass 220 and the solar cell 210 to reduce the thickness and weight of the cover glass 220; A polymer sheet 230 and a plurality of bonding sheets 240 laminated above and below the solar cell 210 and a back sheet 240 positioned on the rear surface of the solar cell 210 to protect the solar cell 210. [ sheet, 250).

The cover glass 220 uses reinforced or semi-tempered glass to prevent damage to the solar cell 210 and the solar module. In particular, the cover glass 220 has a low transmittance iron It is preferable to use semi-tempered glass. The cover glass 220 of this embodiment is configured to be thinner than the thickness of the tempered glass (3.2 to 3.8 mm) constituting the cover glass of a general solar module. Thus, the weight of the cover glass which occupies a large part of the total weight of the solar module can be reduced, while the strength can be weakened. Therefore, the solar module 200 of this embodiment is configured to further include the polymer sheet 230 described later.

The polymer sheet 230 is used for reinforcing the strength of the cover glass 220 while reducing the thickness and weight of the cover glass 220. The polymer sheet 230 is made of a lightweight flexible material using a different material from the cover glass 220. Examples of the polymer sheet 230 include polycarbonate (PC), polyether sulfone (PES), polymethyl methacrylate (PMMA), polyimide (PI), polyethylene naphthalate (PEN) .

The bonding sheet 240 is disposed above and below the polymer sheet 230 and the solar cell 210 so as to buffer the solar cell 210 up and down and to bond the respective layers together. The bonding sheet 240 includes an ethylene vinyl acetate sheet (EVA sheet, Ethylene Vinyl Acetate sheet) and Olefin sheet. Meanwhile, the bonding sheet 240 also functions to prevent water and dust from penetrating into the polymer sheet 230 and the solar cell 210 through perfect interlayer bonding.

The back sheet 250 is disposed on the rear surface of the solar cell 210 and protects the solar cell 210 from the external environment. The back sheet 250 is made of a Teflon material.

On the other hand, the cover glass 220 and the polymer sheet 230 are integrated by the bonding sheet 240 to constitute the heterogeneous bonded cover glass according to the present invention. Such a hetero-junction cover glass has a structure in which the thickness of the cover glass 220 is thinned and reinforced with the polymer sheet 230, so that durability, strength, and transmission characteristics can be satisfied while reducing the total weight.

Hereinafter, experimental examples in which the heterogeneous bonded cover glass according to the present invention is manufactured by various materials and methods will be described.

FIG. 4 is a conceptual diagram of a heterojunction cover glass according to an embodiment of the present invention, and photographs of a heterojunction cover glass manufactured by various materials and methods according to the conceptual diagram.

The heterogeneous bonded cover glass shown in FIG. 4 was an experimentally manufactured product of the present invention in order to demonstrate mass reduction rate and transmittance change ratio with respect to a commercially available 3.2 mm cover glass. Soda lime glass was used as the cover glass. The thickness of each layered material used in the heterojunction was measured using a soda lime glass (2.1 mm) (corresponding to a cover glass), an EVA sheet (0.5 mm) (corresponding to a bonding sheet or a protective sheet), a polymer sheet (PC sheet- PI sheet-0.25 mm, PES sheet-0.125 mm). Therefore, the thickness of the heterogeneous bonded cover glass of each of the inventive examples (EVA sheet / polymer sheet / EVA sheet / cover glass) when the heterojunction was completed was 3.225 mm when the PC sheet was applied and 3.35 mm when the PI sheet was applied And 3.225 mm when the PES sheet is used.

In the production of the inventive products as shown in FIG. 4, a heterojunction process was used. This heterogeneous bonding process was carried out using lamination equipment, and process temperature, process time and process pressure were applied as process parameters of the lamination equipment. That is, the cover glass, the EVA sheet, the polymer sheet, and the EVA sheet were sequentially laminated as shown in the conceptual view of FIG. 4, and then inserted into the lamination equipment, and the experiment was conducted according to the process conditions.

Here, the EVA sheet has to have a high transmittance characteristic so as to transmit the incident light from the outside well as a buffering function to protect the solar cell. In order to maintain such characteristics, the optimum characteristics are shown under the process conditions (temperature: 120 ° C, pressure: 100 kPa, time: 6 minutes and 35 seconds). Therefore, the experiment was carried out based on the above three process conditions, and the process variables (temperature) shown in the following experimental data were processed in order to find the optimum conditions because the characteristics of each polymer sheet were different. The actual bonded heterogeneous cover glass was processed at process temperature (100 ℃, 120 ℃, 140 ℃, 160 ℃), process pressure (100kPa) and process time (20min 10sec) Characteristics were analyzed. If the process pressure, process time, and process temperature are too low, there is a problem that the degree of bonding of the EVA sheet is lowered and peeling phenomena may occur between the respective components. Conversely, if the process pressure, process time and process temperature are too large, Thereby reducing the efficiency of the hetero-junction cover glass.

Observations of the mass reduction rate and the rate of change of permeability for the comparative examples of the 3.2 mm cover glass and the examples of the heterojunction cover glass prepared for each of the three types of polymer sheets under the above conditions were observed.

1) Mass reduction rate

The mass reduction rates shown in the graphs of Figures 10 to 12 are based on a 3.2 mm soda lime glass (100 x 100 x 3.2 mm ³ ), a heterogeneously bonded cover glass (3.225 mm-PC sheet, PES Sheet utilization / 3.35 mm-PI sheet). Table 1 shows the basic information on soda lime glass.

Soda lime glass substrate (SLG) size Volume (cm ³ ) Mass (g) Relative density (g / cm ³ ) 300x300x2.1mm ³ 189.00 457.77 2.42 100x100x3.2mm ³ 32.00 77.51 2.42

In fact, the size of the sodalime glass used for the heterojunction was 300 x 300 x 2.1 mm ^3, and the size of the produced heterogeneous cover glass was cut to 100 x 100 mm ² for various analyzes. For the mass change rate, the volume and mass of the soda lime glass (300 x 300 x 2.1 mm ³ ) actually held was measured and compared with the thickness of 3.2 mm, and the relative density was obtained. 100 x 100 x 3.225 (PC sheet, PES sheet used) / 3.35 (PI sheet used) was calculated as the mass of the 100 x 100 x 3.2mm ³ days to change in mass compared with the ³ mm). That is, 77.51 g and the rate of change of mass were calculated by changing the mass of the heterogeneous cover glass product (PC sheet, PI sheet and PES sheet).

The mass change rate of the heterogeneous bonded cover glass prepared for each polymer sheet is summarized in Table 2 below. As can be seen in Table 2, there is a slight difference in each polymer sheet, but a mass reduction rate of about 20% in the latter half of the 100 x 100 x 3.2 mm ³ cover glass appears.

division PC sheet PI sheet PES sheet Temperature (℃) Actual mass (g) Mass reduction rate (%) Actual mass (g) Mass reduction rate (%) Actual mass (g) Mass reduction rate (%) 100 55.76 28.21 56.89 27.62 56.74 28.17 120 54.24 28.37 56.73 27.10 56.55 27.34 140 55.34 29.25 56.90 27.47 55.71 29.12 160 54.86 30.09 56.31 27.14 56.05 27.83 Average 55.01 28.98 56.71 27.33 56.26 28.12

2) Permeation change rate

The actually produced heterogeneous cover glass was made of EVA sheet (corresponding to protective sheet) / polymer sheet / EVA sheet (corresponding to bonding sheet) / soda lime glass. The properties of the polymer sheet / EVA sheet / soda lime glass were verified when analyzing the actual permeation characteristics, because the bonding loss and the damage of the polymer sheet surface due to the vertical pressure during the lamination process were minimized.

FIG. 5 is a schematic view showing the principle of measurement of the transmittance of the heterojunction cover glass of FIG. As a measurement method, as shown in the schematic diagram of FIG. 5, the transmittance of EVA sheet is measured by measuring the transmittance of EVA sheet / soda lime glass based on soda lime glass using soda lime glass and EVA sheet / soda lime glass product. Then, when the transmittance of the heterogeneously bonded cover glass (EVA sheet / polymer sheet / EVA sheet / soda lime glass) actually measured based on the EVA sheet is measured, ultimately, the transparency of the polymer sheet / EVA sheet / soda lime glass is obtained .

FIGS. 6 to 9 are graphs showing the transmittance of the heterogeneous bonded cover glass shown in FIG. 4, respectively. As can be seen from FIGS. 6 to 9, permeability characteristics according to temperatures (100 ° C., 120 ° C., 140 ° C. and 160 ° C.) under a constant process pressure (100 kPa) and a process time (20 minutes and 10 seconds) The transmittance of heterogeneous cover glass tends to increase as the temperature increases.

FIGS. 10 to 12 are graphs comparing the transmittance and the mass reduction rate between the hetero-junction cover glass shown in FIG. 4 and the conventional cover glass. FIG. 10 is a graph when a PC sheet is applied, FIG. 12 is a graph when a PES sheet is applied. FIG. FIGS. 10 to 12 show results obtained by selecting only the transmission characteristics at 550 nm in the entire wavelength region and by using lamination process temperatures. In the case of using the 550 nm region, the wavelengths used as transmission indices Area.

The dotted lines in FIGS. 10 to 12 are for comparing the transmission rate of the heterogeneous cover glass produced according to the lamination process temperature at 550 nm of soda lime glass (2.1 mm). As can be seen from FIG. 11, in the case of the heterogeneous cover glass made using the PI sheet, the transmittance was low in the region of 300 to 800 nm due to the nature of the polymer. However, as can be seen from FIGS. 10 and 12, the heterobifunctional cover glass prepared using PC or PES sheet exhibited a property close to the transmittance of soda lime glass as the process temperature was increased. It can be seen that the heterogeneous bonded cover glass to which the PC sheet is applied has the most excellent transmittance characteristics.

On the other hand, as can be seen from FIGS. 10 to 12, the mass reduction rate of the heterogeneous bonded cover glass produced by using three kinds of different polymers (PC, PI, PES sheets) is about 20% The mass reduction rate is shown. That is, it can be seen that the cover glass manufactured using the polymer sheet under the condition of having the same thickness can significantly reduce the weight of the cover glass which occupies a large weight proportion in the entire solar cell module.

As a result, it can be seen that the heterogeneous cover glass according to the present invention not only has a mass reduction rate of the second half of 20% as compared with the cover glass according to the conventional 3.2 mm standard, but also has a similar transmittance to the conventional one.

FIG. 13 is a conceptual view showing a cross section of a solar module having a heterojunction cover glass according to another embodiment of the present invention, FIG. 14 is a view showing the cover glass of the prior art shown in FIG. 1, Fig. 2 is a conceptual diagram showing a comparison of the heterogeneous bonded cover glass of Fig.

13 and 14, the photovoltaic module 300 according to this embodiment is the same as the solar cell module 300 except that the cover glass 320 and the polymer sheet 330 are integrated without a bonding sheet to form a heterogeneous bonded cover glass Is configured in the same manner as the solar module 200 shown in FIG. That is, the solar module 300 according to this embodiment includes a solar cell 310 for converting the light energy of solar light into electric energy, a cover glass 310 for protecting the solar cell 310, A polymer sheet 330 integrally formed on the rear surface of the cover glass 320 to reduce the thickness and weight of the cover glass 320 and a pair of bonding sheets 340 and a back sheet 350 positioned on the rear surface of the solar cell 310 to protect the solar cell 310.

In the meantime, the hetero-junction cover glass of this embodiment is obtained by integrating the cover glass 320 and the polymer sheet 330 without a bonding sheet. To this end, the process temperature is increased to the melting point corresponding to each type of the polymer sheet 330 during the lamination process , It is possible to integrate without a separate bonding sheet. That is, by raising the process temperature to a temperature higher than the melting point of the polymer during the lamination process, it is possible to manufacture a heterogeneous cover glass in which the cover glass 320 and the polymer sheet 330 are integrated by a simple method without a separate bonding sheet. That is, the heterojunction cover glass of this embodiment has a form in which the cover glass 320 and the polymer sheet 330 are melt-bonded.

Although the present invention has been described with reference to the accompanying drawings, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined by the appended claims. Examples or modifications will also fall within the scope of the claims of this invention.

200: solar module 210: solar cell
220: cover glass 230: polymer sheet
240: Bonding sheet 250: Back sheet

Claims (10)

Solar cells that convert solar light energy into electrical energy;
A cover glass disposed on a front surface of the solar cell to receive sunlight to protect the solar cell;
A polymer sheet interposed between the cover glass and the solar cell to reinforce the cover glass;
A back sheet disposed on a rear surface of the solar cell to protect the solar cell; And
And a bonding sheet laminated between the polymer sheet and the cover glass and above and below the solar cell to bond the solar cell and the back sheet to each other and to bond the solar cell and the polymer sheet to each other,
Wherein the heterogeneous bonded cover glass laminated in the order of the laminated sheet, the polymer sheet and the cover glass has a mass reduction rate of 27.10% to 30.09% as compared with the cover glass having the same relative density, size and thickness. delete The method according to claim 1,
The polymer sheet may be one of a polycarbonate (PC), a polyether sulfone (PES), a polymethyl methacrylate (PMMA), a polyimide (PI), or a polyethylene naphthalate . ≪ / RTI > The method according to claim 1,
Wherein the bonding sheet is an ethylene vinyl acetate sheet (EVA sheet) or an olefin sheet. delete delete delete delete delete delete

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