WO2014115837A1

WO2014115837A1 - Cover glass for solar cell, and solar cell module

Info

Publication number: WO2014115837A1
Application number: PCT/JP2014/051492
Authority: WO
Inventors: 裕介小林; 幸史桶谷; 忠久金杉; 哲菊地; 泰子一山; 小島　浩士
Original assignee: 旭硝子株式会社
Priority date: 2013-01-24
Filing date: 2014-01-24
Publication date: 2014-07-31
Also published as: JP5812210B2; TW201442973A; CN104936915A; JPWO2014115837A1

Abstract

A cover glass for a solar cell having a glass plate having first and second principal surfaces and edge surfaces disposed between the first and second principal surfaces, the cover glass for a solar cell being characterized in that the glass plate has a plate thickness of 0.5 to 1.5 mm and has been subjected to a chemical strengthening treatment, the principal surfaces have a surface compressive stress value of 400 to 1000 MPa, the thickness in the plate thickness direction of a compressive stress layer on the principal surfaces is 15 to 50 μm, and the glass plate has a concentric circle bend strength of at least 30 kgf.

Description

Cover glass for solar cell and solar cell module

The present invention relates to a cover glass for a solar cell and a solar cell module, and more particularly to a cover glass for a solar cell that can achieve reduction of damage in long-term use even if the plate thickness is thin due to a chemical strengthening treatment, and the sun using the same The present invention relates to a battery module.

Solar power generation has become widespread due to concerns about exhaustion of fossil energy resources. In particular, due to the power purchase system in Japan, there are an increasing number of cases where solar cell modules are installed on the roofs and rooftops of ordinary households, factories, buildings, and the like.

In order to install solar cell modules on these roofs and rooftops, it is necessary to ensure sufficient vibration resistance of the building. For example, in the case of new construction, a structural design of a building is made in consideration of a load caused by installing a solar cell module on a roof / rooftop.

However, there is a case where a built building called an existing building does not assume the installation of a solar cell module on the roof / rooftop at the initial design stage. There is also a concern that the installation of solar cell modules on the roof or roof of such an existing property will result in insufficient seismic strength and wind pressure strength of the entire building (this concern is referred to as concern 1).

Also, a plan for a solar power plant with a large number of solar cell modules installed on a vast site is underway. For example, in a solar power plant of several tens MW class described in the planning stage, 100,000 or more solar cell modules may be installed.

For businesses deploying solar power plants, it is important to reduce the man-hours required to install solar cell modules and start up power plants in order to ensure business benefits and public benefit. Therefore, an increase in the number of man-hours required for installing a large number of solar cell modules is a major concern and concern. Concerns about the increase in man-hours are small compared to solar power plants, but the same applies to the installation of solar cell modules on the roofs and roofs of the above-mentioned newly constructed buildings. Called).

As an effective means for solving the concerns 1 and 2, it is possible to reduce the weight of the solar cell module. For this reason, many proposals have been made to reduce the weight of each part of the solar cell module. One proposal is to make the cover glass of the solar cell module thinner.

As a typical cover glass thickness, a thickness of about 3 mm has been conventionally used, but in recent years, a thickness of about 1 mm has been proposed.

International Publication No. 2012/108417

By the way, when installing a solar cell module on a roof or a roof, whether it is an existing building or a new building, it is necessary to ensure earthquake resistance and wind pressure resistance as a building and durability as an individual solar cell module. For example, considering the strength against flying objects and the strength against snow load, the strength of the cover glass is ensured. These strengths are represented by a mechanical load test according to JIS C8990. Even if the cover glass is thinned to about 1.5 mm or less to reduce the weight of the solar cell module, it is considered that the glass plate constituting the cover glass is strengthened to ensure good strength. Yes. In the case of a glass plate having a plate thickness of about 1.5 mm or less, chemical strengthening treatment can be considered as this strengthening treatment.

However, the existing standards for these strengths do not take into account issues in long-term use. That is, buildings and solar power plants are assumed to be used in units of several tens of years. Until now, no attention has been paid to the state of the surface of the cover glass when the period has passed.

The solar cell module is used outdoors, and many scratches can occur on the surface of the cover glass in the process of outdoor installation for many years. Therefore, even if the strength against various events is secured at the initial stage, the strength may not be sufficiently secured after long-term use. In particular, it has not been investigated whether a glass plate of 1.5 mm or less subjected to chemical strengthening treatment has strength as a cover glass for solar cells after such a long period of time has passed.

The present invention has an object to provide a cover glass for a solar cell that contributes to weight reduction for wiping out concerns 1 and 2 in installation, and that takes into account changes over time.

The present invention relates to a solar cell cover glass having a glass plate having first and second main surfaces and an end surface interposed between the first and second main surfaces.
The glass plate has a thickness of 0.5 to 1.5 mm and is chemically strengthened.
The surface compressive stress value of the main surface is 400 to 1000 MPa, and the thickness of the compressive stress layer on the main surface in the thickness direction is 15 to 50 μm,
The glass plate provides a cover glass for a solar cell, characterized in that a concentric bending strength obtained by the following method is 30 kgf or more:
(1) Obtain a square glass piece having a length of 50 mm and a width of 50 mm in plan view from the glass plate,
(2) A square 400 mm of 10 mm × 10 mm along a line translated from the center line in the horizontal direction of the glass piece up and down by 10 mm each and 3 mm to the right from the center line in the vertical direction. The sandpaper of the count is reciprocated three times with a load of 1.5 kgf to form a rubbing line having a length of 20 mm in the vertical direction on the first main surface,
(3) On the support ring having a diameter of 30 mm, the first main surface of the glass piece is in contact with the support ring, and the glass piece and the center point of the support ring overlap so that the glass piece is placed on the support ring. Installed in
(4) A load ring having a diameter of 10 mm is placed on the glass piece so that the center points of the two overlap.
(5) When a load is applied to the glass piece from the load ring side at 1 mm / min, the load at which the glass piece is broken is defined as a concentric bending strength.

Moreover, this invention provides a solar cell module provided with such a cover glass for solar cells.

According to the present invention, it is possible to obtain a cover glass for a solar cell that contributes to weight reduction for wiping out the concerns 1 and 2 in installation, and has ensured strength after long-term use.

It is the perspective view which showed an example of the cover glass for solar cells of this invention. It is the figure which showed roughly the measuring method of the concentric-circle bending strength of a glass piece. FIG. 2A shows a state in which rubbing lines are formed on the glass piece, and FIG. 2B shows a state in which a load is applied to the glass piece. It is the general | schematic fragmentary sectional view which showed an example of the solar cell module of this invention.

Hereinafter, an example of the cover glass for a solar cell of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing an example of the cover glass for a solar cell of the present invention. The solar cell cover glass 1 is composed of a glass plate 10 having a thickness t of 0.5 to 1.5 mm. The glass plate 10 has the 1st and 2nd

main surfaces

11a and 11b and the end surface 12 interposed between the

main surfaces

11a and 11b. The glass plate 10 is a chemically strengthened glass plate having a compressive stress layer of 15 to 50 μm in the plate thickness direction on the

main surfaces

11a and 11b. The compressive stress values of the

main surfaces

11a and 11b are 400 to 1000 MPa.

Furthermore, this glass plate 10 is a glass plate having a high bending strength after a predetermined scratch is applied to the main surface 11a. That is, in this glass plate 10, a glass piece cut out to 50 mm in length and 50 mm in width has a predetermined concentric bending strength.

The predetermined concentric bending strength will be described with reference to FIG.

FIG. 2 is a diagram schematically showing a method for measuring the concentric bending strength of a glass piece. FIG. 2A shows a state in which rubbing lines are formed on the glass piece, and FIG. 2B shows a state in which a load is applied to the glass piece.

When measuring the concentric bending strength of a glass piece, first, a square glass piece 100 having a length of 50 mm and a width of 50 mm in a plan view is collected from the glass plate 10. The glass piece 100 is cut out so that, for example, the front view center point of the glass plate 10 becomes the center point of the glass piece 100.

Next, as shown in FIG. 2 (a), along the line translated from the center line HL in the horizontal direction of the glass piece 100 by 10 mm above and below from the center line VL in the vertical direction and 3 mm to the right from the center line VL in the vertical direction. Then, a 10 mm × 10 mm square 400th sandpaper is reciprocated three times with a load of 1.5 kgf, whereby a rubbing line 50 having a length of 20 mm in the vertical direction is formed on the first main surface 11a of the glass piece 100. Is formed.

Next, as shown in FIG. 2B, the glass piece 100 is placed on the support ring 30 having a diameter of 30 mm. At this time, the glass piece 100 is placed on the support ring 30 such that the first main surface 11a of the glass piece 100 is in contact with the support ring 30 and the center points of the glass piece 100 and the support ring 30 are overlapped. Is done.

Next, a load ring 40 having a diameter of 10 mm is placed on the glass piece 100 (second main surface thereof). At this time, the load ring 40 is installed on the glass piece 100 so that both center points of the glass piece 100 and the load ring 40 overlap.

Next, in this state, a load is applied to the glass piece 100 from the load ring 40 side at a rate of 1 mm / min. The load at which the glass piece 100 is broken by this load application is defined as a concentric bending strength.

The glass plate 10 has a feature that the concentric bending strength measured by this method is 30 kgf or more.

Next, the principle that it is beneficial to use a glass plate having such a predetermined strength for the cover glass of the present invention will be described. As described above, conventionally, scratches that may occur on the main surface of the glass plate as a result of long-term use have not been fully considered. As a result of tackling a new problem that has not been considered in the past, the present inventors have found that the glass plate of the present invention is suitable for a cover glass for a solar cell.

That is, in the outdoor use environment for many years, fine scratches are caused by the dust that comes in, the dust that adheres, or dust rubs the main surface. Such scratches increase as the period of use increases. Until now, the depth of scratches resulting from use in an outdoor use environment for a long time, for example, 10 years has not been sufficiently studied, but the present inventors have found that the depth of these scratches is about 10 μm. It was. Further, the number of scratches that occurred after outdoor use for about 10 years was in the range of 10/400 cm ² to 50/400 cm ² . The number of such scratches varies depending on the area of use, and increases in areas with high traffic such as coastal areas, cars, and railways.

At this time, if the plate thickness is about 3 mm as in the case of a conventional cover glass, the cover glass itself has rigidity, so that the deflection due to a static load such as wind or snow can be suppressed. However, when the plate thickness is 1.5 mm or less, the deflection due to these static loads increases. As a result, since the main surface is scratched, the cover glass is easily broken starting from the scratch.

In order to reduce this ease of cracking, the solar cell module itself can be structured to reduce the deflection of the cover glass by attaching a frame to the periphery or a reinforcing rail on the back side. . However, for this purpose, the weight increases due to the addition of these reinforcing members, and the effect of thinning the cover glass is reduced.

Therefore, the strength of the cover glass after long-term use can be maintained without adding an excessive reinforcing member by using a glass plate having a high bending strength after applying a predetermined scratch like the cover glass of the present invention. . In particular, the solar cell module using the cover glass of the present invention exhibits good durability without using an excessive reinforcing member. For example, the solar cell module using the cover glass of the present invention clears JIS C8990 “mechanical load test” and exhibits good durability against wind and snow even after long-term use.

The glass plate in the present invention is preferably a glass plate in which the above glass piece has a concentric circular bending strength of 70 kgf or more. In this case, even if damage that can be assumed after long-term use occurs, a bending strength equal to or higher than the bending strength of the cover glass obtained when a glass plate having a thickness of about 3 mm is used can be obtained. Thereby, as a solar cell module, the addition of a reinforcing member for supplementing the strength reduction which is a concern due to the thin cover glass is eliminated.

The glass plate of the present invention preferably has a surface compressive stress value of 550 to 800 MPa on the main surface and a thickness in the plate thickness direction of the compressive stress layer on the main surface of 20 to 45 μm. This is because if the surface compressive stress value of the main surface and the thickness of the compressive stress layer on the main surface in the thickness direction are too large, the internal tensile stress value becomes excessively large. In other words, in addition to the occurrence of scratches during long-term use, sharp objects may collide strongly with the cover glass due to falling rocks, stones, or traps. Such a collision of the object causes a crack that penetrates the compressive stress layer of the main surface. At that time, if the internal tensile stress is too large, the fracture is likely to proceed. From this point, the tensile stress value inside the glass plate in the present invention is preferably 10 to 60 MPa.

As the glass plate in the present invention, it is useful that the area of the main surface is 1 m ² or more to exhibit the effects of the present invention. That is, if the area of the solar cell module increases, the absolute value of deflection tends to increase. Therefore, if it is a conventional glass plate, the reinforcing member necessary to suppress such deflection becomes excessive, but if it is a glass plate in the present invention, the bending strength after long-term use, that is, after scratches are added Therefore, it is not necessary to increase the number of reinforcing members.

It is useful that the thickness of the glass plate in the present invention is 0.7 to 1.2 mm, and further less than 1.0 mm, as an effect of the present invention. That is, if the thickness of the glass plate decreases, the absolute value of the deflection tends to increase. Therefore, if it is a conventional glass plate, the reinforcing member necessary to suppress such deflection becomes excessive, but if it is a glass plate in the present invention, the bending strength after long-term use, that is, after scratches are added Therefore, it is not necessary to increase the number of reinforcing members.

The glass plate in the present invention may have a compressive stress layer formed on the end surface as well as the main surface. However, for example, when the glass plate is cut into a desired shape after chemical strengthening, the compressive stress layer may not exist on the end face. Even if the compressive stress in this invention is uniformly formed in the main surface direction of the glass plate, it may have distribution within a surface. According to the above chemical strengthening treatment, compressive stress can be obtained almost uniformly except for treatment unevenness. Therefore, when measuring various values related to compressive stress, the center of the main surface (a point where diagonal lines intersect when the glass plate is rectangular, or a point corresponding to this when the glass plate is not rectangular) may be used as a representative point.

The method of chemical strengthening treatment for obtaining the glass plate in the present invention is not particularly limited as long as it can ion-exchange Na in the glass surface layer and K in the molten salt, but for example, heated potassium nitrate molten salt The method of immersing glass is mentioned. Incidentally, potassium nitrate molten salt, or potassium nitrate salts in the present invention other KNO _3, including those containing KNO ₃ and 10 wt% or less of NaNO _3.
The chemical strengthening treatment conditions for forming a compressive stress layer having a desired surface compressive stress on glass vary depending on the thickness of the glass plate, but the glass substrate is immersed in molten potassium nitrate at 350 to 550 ° C. for 2 to 20 hours. It is typical. From an economical point of view, it is preferable to immerse under conditions of 350 to 500 ° C. and 2 to 16 hours, and a more preferable immersion time is 2 to 10 hours.

There are no particular restrictions on the method for producing the glass plate in the present invention. For example, an appropriate amount of various raw materials are prepared, heated to about 1400-1800 ° C. and melted, and then homogenized by defoaming, stirring, etc. It is manufactured by forming into a plate shape by a downdraw method, a press method, etc., and then cooling to a desired size after slow cooling.

It is preferable that the glass transition point Tg of the glass of the glass plate in this invention is 400 degreeC or more. Thereby, relaxation of the surface compressive stress during ion exchange can be suppressed. More preferably, it is 550 degreeC or more.
The temperature T2 at which the viscosity of the glass of the glass plate in the present invention is 10 ² dPa · s is preferably 1800 ° C. or lower, more preferably 1750 ° C. or lower.
The temperature T4 at which the viscosity of the glass in the present invention is 10 ⁴ dPa · s is preferably 1350 ° C. or lower.

The specific gravity ρ of the glass plate in the present invention is preferably 2.37 to 2.55.
The Young's modulus E of the glass plate in the present invention is preferably 65 GPa or more. As a result, the rigidity and breaking strength of the glass cover glass are sufficient.
The Poisson's ratio σ of the glass plate in the present invention is preferably 0.25 or less. As a result, the scratch resistance of the glass, particularly the scratch resistance after long-term use, is sufficient.

The glass plate in the present invention is preferably made of the following glass because it is easy to perform chemical strengthening treatment:
Expressed in terms of mole percentage based on oxide, SiO ₂ is 56 to 75%, Al ₂ O ₃ is 5 to 20%, Na ₂ O is 8 to 22%, K ₂ O is 0 to 10%, MgO is 0 to 14 %, ZrO ₂ 0-5%, CaO 0-5% glass. In the following, percentage display refers to the content expressed in mole percentage unless otherwise specified.
SiO ₂ is a component that constitutes the skeleton of glass and is essential, and reduces the occurrence of cracks when scratches (indentations) are made on the glass surface, or the fracture rate when indentations are made after chemical strengthening. It is a component to make small. If the SiO ₂ content is less than 56%, the stability, weather resistance or chipping resistance of the glass is lowered. SiO ₂ is preferably 58% or more, more preferably 60% or more. If SiO ₂ exceeds 75%, the viscosity of the glass increases and the meltability decreases.

Al ₂ O ₃ is an effective component for improving ion exchange performance and chipping resistance, and is a component that increases the surface compressive stress, or a component that decreases the crack generation rate when indented with a 110 ° indenter. And essential. If Al ₂ O ₃ is less than 5%, a desired surface compressive stress value or compressive stress layer thickness cannot be obtained by ion exchange. Preferably it is 9% or more. If Al ₂ O ₃ exceeds 20%, the viscosity of the glass becomes high and uniform melting becomes difficult. Al ₂ O ₃ is preferably 15% or less, typically 14% or less.

The total SiO ₂ + Al ₂ O ₃ content of SiO ₂ and Al ₂ O ₃ is preferably 80% or less. If it exceeds 80%, the viscosity of the glass at high temperature may increase and melting may be difficult, and it is preferably 79% or less, more preferably 78% or less. _Further, it is preferable that SiO 2 + _Al 2 _{O 3} is 70% or more. If it is less than 70%, the crack resistance when an indentation is made decreases, more preferably 72% or more.

Na ₂ O is a component that forms a surface compressive stress layer by ion exchange and improves the meltability of the glass, and is essential. If Na ₂ O is less than 8%, it becomes difficult to form a desired surface compressive stress layer by ion exchange, and it is preferably 10% or more, more preferably 11% or more. If Na ₂ O exceeds 22%, the weather resistance is lowered, or cracks are likely to occur from the indentation. Preferably it is 21% or less.

K ₂ O is not essential, but may be contained in a range of 10% or less in order to increase the ion exchange rate. If it exceeds 10%, cracks are likely to occur from the indentation, or the change in surface compressive stress due to the concentration of NaNO ₃ in the molten potassium nitrate salt may increase. K ₂ O is preferably 5% or less, more preferably 0.8% or less, still more preferably 0.5% or less, and typically 0.3% or less. When it is desired to reduce the change in the surface compressive stress due to the NaNO ₃ concentration in the potassium nitrate molten salt, it is preferable not to contain K ₂ O.

MgO is a component that increases the surface compressive stress and is a component that improves the meltability and is essential. When it is desired to suppress stress relaxation, it is preferable to contain MgO. When MgO is not contained, the degree of stress relaxation tends to change depending on the location of the chemical strengthening treatment tank due to variations in the molten salt temperature when performing chemical strengthening treatment, and as a result, a stable compressive stress value can be obtained. May be difficult. On the other hand, if MgO exceeds 14%, the glass tends to be devitrified, or the change in surface compressive stress due to the concentration of NaNO ₃ in the potassium nitrate molten salt may increase, and it is preferably 13% or less.

The preferred glass component of the glass plate in the present invention consists essentially of the components described above, but may contain other components as long as the object of the present invention is not impaired. When such components are contained, the total content of these components is preferably less than 2%, more preferably 1% or less. Hereinafter, the other components will be described as an example.

ZnO may be contained up to 2%, for example, in order to improve the melting property of the glass at a high temperature, but is preferably 1% or less, and 0.5% or less in the case of manufacturing by a float process. It is preferable to make it. If ZnO exceeds 0.5%, it may be reduced during float molding, resulting in a product defect. Typically no ZnO is contained.
Since TiO ₂ coexists with Fe ions present in the glass, the visible light transmittance is lowered and the glass may be colored brown, so even if it is contained, it is preferably 1% or less. Does not contain.

Li ₂ O is a component that lowers the strain point to facilitate stress relaxation, and as a result makes it impossible to obtain a stable surface compressive stress layer, so it is preferably not contained, and even if it is contained, its content Is preferably less than 1%, more preferably 0.05% or less, and particularly preferably less than 0.01%.

In addition, Li ₂ O may be eluted in a molten salt such as KNO ₃ during chemical strengthening treatment, but when the chemical strengthening treatment is performed using a molten salt containing Li, the surface compressive stress is remarkably reduced. Li ₂ O is preferably not contained from this viewpoint.

CaO may be contained in a range of 5% or less in order to improve the meltability at high temperature or to prevent devitrification. If the CaO content exceeds 5%, the ion exchange rate or the resistance to cracking decreases. Typically no CaO is contained.
SrO may be contained as necessary, but since the effect of lowering the ion exchange rate is greater than that of MgO and CaO, the content is preferably less than 1% even when contained. Typically no SrO is contained.
Since BaO has the greatest effect of reducing the ion exchange rate among alkaline earth metal oxides, BaO should not be contained, or even if contained, its content should be less than 1%. preferable.

When SrO or BaO is contained, the total content thereof is preferably 1% or less, more preferably less than 0.3%.
When one or more of CaO, SrO, BaO and ZrO ₂ are contained, the total content of these four components is preferably less than 1.5%. If the total is 1.5% or more, the ion exchange rate may be lowered, and is typically 1% or less.

Furthermore, the present invention provides a solar cell module using the above glass plates as follows. In a solar cell module comprising a plurality of solar cells, a sealing material that seals the solar cells, and a first cover glass that is disposed to face at least one surface of the sealing material The solar cell module, wherein the first cover glass is a solar cell cover glass using the above glass plates. Furthermore, it is preferable to use each glass plate as a cover glass on both sides of the solar cell module. Thereby, even if it uses a glass plate with high weather resistance compared with the conventional resin backsheet, the weight can be reduced and the strength can be secured.

An example using cover glass on both sides will be described with reference to FIG. In the solar cell module 20, the first cover glass made of each glass plate 10 a and the second cover glass made of each glass plate 10 b are laminated via a sealing material 22. A plurality of solar cells 23 are enclosed in the sealing material 22.

Such a solar cell module of the present invention can be suitably used for a factory roof, a roof of a public transportation station building such as a railroad, and a solar power plant often found in a coastal area. In other words, sand, dust, salt, and the like frequently fly in factories, stations, and coastal areas, and as a result of installation over a long period of time, many scratches are likely to occur on the main surface of the glass plate. On the other hand, the weight reduction of solar cell modules is strongly demanded for factory roofs, railway station roofs, and solar power plants as mentioned in points 1 and 2 above. In such an environment, the use of a solar cell module using a glass plate with high bending strength as a cover glass after being scratched in the present invention makes it possible to reduce the weight while reducing the mechanical load even after long-term use. Can withstand and be beneficial. The station building here includes a stop, an airport, and a port.

Furthermore, in the solar cell module of the present invention, having the structure in which the end face of the cover glass is exposed can achieve the weight reduction of the entire solar cell module. This is not as simple as reducing the number of parts to achieve weight reduction. That is, such a configuration can be realized by using a cover glass having sufficient strength that does not require a frame around the solar cell module that functions as a reinforcing member.

A glass plate for solar cell cover glass as shown in Table 1 below was prepared. In the table, Example 1 is a glass plate according to the cover glass of the present invention, and Examples 2 to 4 are glass plates according to comparative examples.

The glass plates of Examples 1 and 2 are chemically strengthened glass plates. The type of glass plate of Example 1 is LEOFLEX (registered trademark) manufactured by Asahi Glass Co., Ltd., and each reinforced physical property obtained as a result of the chemical strengthening treatment is adjusted to the value shown in the column of “Example 1” in Table 1. is there. The type of the glass plate of Example 2 is soda lime silica glass, and each reinforced physical property obtained as a result of the chemical strengthening treatment is adjusted to the value shown in the column of “Example 2” in Table 1. As reinforcing physical properties, the surface compressive stress CS (unit: MPa) of the main surface and the thickness DOL (unit: μm) of the compressive stress layer on the main surface are measured with a surface stress meter FSM-6000 manufactured by Orihara Seisakusho. did. Moreover, internal tensile stress CT (unit: MPa) was calculated from these values. In addition, the kind of glass plate of Examples 3 and 4 is soda-lime silica glass.

From these glass plates of Examples 1 to 4, glass pieces having a length of 50 mm and a width of 50 mm were cut out in plan view, and the number of glass pieces shown in Table 1 was concentrically bent (unit: kgf) by the following method. ) Was measured. In the following description, the measurement method will be described using the reference symbols shown in FIG. 2 for the sake of clarity.

(Rubbing line forming step)
In the square glass piece 100 of 50 mm long × 50 mm wide, a line (rubbed area) translated from the center line HL in the horizontal direction in a plan view to a range of 10 mm vertically and 3 mm to the right from the center line VL in the vertical direction Determine. Next, 400 mm sandpaper having a square shape of 10 mm × 10 mm is fixed to the tip of the load cell. The load cell is reciprocated three times along the rubbing region while applying a load of 1.5 kgf to the glass piece 100 to form a rubbing line 50 having a length of 20 mm on one main surface of the glass piece 100.

(Concentric bending strength measurement step)
The main surface of the glass piece 100 on which the rubbing line 50 is formed is placed on the support ring 30 having a diameter of 30 mm. Next, a load ring 40 having a diameter of 10 mm is placed thereon. At this time, the respective members are placed so that the center points of the glass piece 100, the support ring 30, and the load ring 40 overlap each other. Then, a load is applied to the glass piece 100 at 1 mm / min from the load ring 40 side to obtain a load when the glass piece is broken.

The measured load is the concentric bending strength (unit: kgf).

In Table 1, “concentric bending strength before rubbing line application” is the concentric bending strength (unit: kgf) obtained when the above rubbing line forming step was not performed.

The glass plate of Example 1 has a bending strength greater than the average value of the concentric bending strength before forming the rubbing line of the glass plate of Example 2 because the concentric bending strength after forming the rubbing line is 70 kgf or more. is there. That is, like the glass plate of Example 2, by providing a certain strength at the initial stage, it may be possible to obtain a cover glass that can reduce the plate thickness and achieve weight reduction. On the other hand, it can be said that the glass plate of Example 1 has sufficient strength even after scratches are formed as a result of long-term use. Furthermore, the glass plate of Example 1 is more than the bending strength after a flaw is formed as a result of long-term use of a glass plate having a large plate thickness like the glass plate of Example 4. As described above, the glass plate of Example 1 has bending strength after long-term use that is comparable to a glass plate having a large thickness even if the thickness is reduced in order to reduce the weight of the solar cell module.

The cover glass for a solar cell of the present invention wipes away the concerns at the time of installing the solar cell module, is lightweight, and can secure strength even when installed outdoors for a long period of time.

Also, this application claims priority based on Japanese Patent Application No. 2013-010834 filed on January 24, 2013, the entire contents of which are incorporated herein by reference.

DESCRIPTION OF SYMBOLS 1 Solar cell cover glass 10 Glass plate 11a 1st main surface 11b 2nd main surface 12 End surface 30 Support ring 40 Load ring 40
50 rubbing line 100 piece of glass

Claims

In a solar cell cover glass having a glass plate having first and second main surfaces and an end surface interposed between the first and second main surfaces,
The glass plate has a thickness of 0.5 to 1.5 mm and is chemically strengthened.
The surface compressive stress value of the main surface is 400 to 1000 MPa, and the thickness of the compressive stress layer on the main surface in the thickness direction is 15 to 50 μm,
The glass plate has a concentric bending strength obtained by the following method of 30 kgf or more, and is a solar cell cover glass:
(1) Obtain a square glass piece having a length of 50 mm and a width of 50 mm in plan view from the glass plate,
(2) A square 400 mm of 10 mm × 10 mm along a line translated from the center line in the horizontal direction of the glass piece up and down by 10 mm each and 3 mm to the right from the center line in the vertical direction. The sandpaper of the count is reciprocated three times with a load of 1.5 kgf to form a rubbing line having a length of 20 mm in the vertical direction on the first main surface,
(3) On the support ring having a diameter of 30 mm, the first main surface of the glass piece is in contact with the support ring, and the glass piece and the center point of the support ring overlap so that the glass piece is placed on the support ring. Installed in
(4) A load ring having a diameter of 10 mm is placed on the glass piece so that the center points of the two overlap.
(5) When a load is applied to the glass piece from the load ring side at 1 mm / min, the load at which the glass piece is broken is defined as a concentric bending strength.
2. The cover glass for a solar cell according to claim 1, wherein a surface compressive stress value of the main surface is 550 to 800 MPa, and a thickness of the compressive stress layer on the main surface in a plate thickness direction is 20 to 45 μm.
The solar cell cover glass according to claim 1 or 2, wherein the concentric circular bending strength is 70 kgf or more.
The solar cell cover glass according to any one of claims 1 to 3, wherein an internal tensile stress value of the glass plate is 10 to 60 MPa.
The cover glass for a solar cell according to any one of claims 1 to 4, wherein an area of the main surface is 1 m 2 or more.
The solar cell cover glass according to any one of claims 1 to 5, wherein the plate thickness is 0.7 to 1.2 mm.
The cover glass for solar cells according to claim 6, wherein the plate thickness is less than 1.0 mm.
The glass plate is expressed in terms of mole percentage based on oxide, and SiO 2 is 56 to 75%, Al 2 O 3 is 5 to 20%, Na 2 O is 8 to 22%, K 2 O is 0 to 10%, The solar cell cover glass according to any one of claims 1 to 7, comprising a glass containing 0 to 14% of MgO, 0 to 5% of ZrO 2 and 0 to 5% of CaO.
In a solar cell module comprising a plurality of solar cells, a sealing material for sealing the plurality of solar cells, and a first cover glass disposed on at least one surface of the sealing material,
A solar cell module, wherein the first cover glass is the solar cell cover glass according to any one of claims 1 to 8.
The solar cell module according to claim 9, wherein an end face of the first cover glass is exposed.
The solar cell cover glass according to any one of claims 1 to 8, wherein a second cover glass is disposed on a side opposite to the first cover glass side, and the second cover glass is also the solar cell cover glass according to any one of claims 1 to 8. The solar cell module according to claim 9 or 10.
The solar cell module according to any one of claims 9 to 11, for factory roof installation, public transportation station building roof installation, or for a solar power plant.