JP2000049372A - Insulation substrate for solar battery and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulation substrate for a solar battery that is hard to be broken, has flexibility, can be made lighter than a glass substrate, and can increase the utilization efficiency of the light of the solar cell. SOLUTION: In an insulation substrate for a solar battery with an insulation layer on the surface of a metal plate, the thickness of the insulation layer is equal to or more than 0.5 μm, and at the same time, the surface roughness of the insulation layer ranges from 0.5 to 200 μm in terms of center line average roughness Ra. For manufacturing the insulation substrate for the solar battery, the surface shape of a metal plate is adjusted using acidic or alkaline solution and then an insulation layer is formed on the metal plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating substrate for a solar cell and a method of manufacturing the same, and more particularly, to a technical field of an insulating substrate for a solar cell having an insulating layer on a surface of a metal plate and a method of manufacturing the same. Belong.

[0002]

2. Description of the Related Art As an electronic material substrate, a substrate made of glass (glass substrate) may be used in applications requiring electrical insulation, but care must be taken when handling the substrate because it is easily broken. In addition, the use range was limited due to lack of flexibility. In particular, glass substrates are also used for large-sized ones such as solar cells (solar panels), and the problem is remarkable.

Recently, solar cells have attracted attention as a power supply source for buildings such as houses, and in order to secure sufficient power supply, it is essential to increase the size of the solar cells. In order to achieve this, it is desired to reduce the weight of the substrate. However, if the thickness of the glass substrate is reduced for the purpose of reducing the weight, the glass substrate is more easily broken. Under such circumstances, there is a demand for the development of a substrate material which is hard to break and is flexible, and which can be lighter than a glass substrate.

[0004] Although a metal material is hard to be broken even when it is thin, it is hardly considered as an insulating substrate material replacing glass because it is a conductor. Insulated metal plates for printed wiring boards and the like have been proposed (Japanese Patent Application Laid-Open No. 5-191001). However, these are not considered in terms of area, insulating property, and surface shape in consideration of the characteristics as solar cell substrates. In addition, it does not satisfy the required characteristics as a solar cell substrate, and sufficient performance cannot be obtained even when applied as a solar cell substrate.

On the other hand, it is known that when the substrate surface of a solar cell has a fine unevenness (texture structure), light is scattered and the light utilization efficiency of the solar cell is increased (for example, see Japanese Patent Application Laid-Open Publication No. 8-18084). A texture structure is also formed on a glass substrate by forming a crystal directional film. As a technique for providing fine irregularities on the surface of a metal plate, an electrochemical dissolution method or the like is known as a means for improving adhesion to a photosensitive layer of a lithographic printing plate (JP-A-10-16419, JP-A-8-179496). However, this technology is not intended to increase the light use efficiency, but to improve the adhesion between the metal plate and the photosensitive layer. Even if it is applied to a substrate for use, a sufficient effect on light use efficiency cannot be obtained.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to make it hard to break, to have flexibility, and to reduce the weight more than a glass substrate. It is an object of the present invention to provide a solar cell insulating substrate and a method for manufacturing the same, which can increase the light use efficiency of the solar cell.

[0007]

In order to achieve the above object, an insulating substrate for a solar cell and a method of manufacturing the same according to the present invention are provided. 8. The method for manufacturing an insulating substrate for a solar cell according to Item 8, which has the following configuration.

That is, the insulating substrate for a solar cell according to the first aspect is a solar cell insulating substrate having an insulating layer on a surface of a metal plate, wherein the thickness of the insulating layer is 0.5 μm or more, The surface roughness of the insulating layer is the center line average roughness (R
a) An insulating substrate for a solar cell, wherein the thickness is 0.5 to 200 μm in (a) (first invention).

According to a second aspect of the present invention, in the insulating substrate for a solar cell, the inclined surface of the uneven portion on the surface of the insulating layer has an inclination angle of 80 degrees or less, and the inclination angle in the inclined surface is 30 degrees or more and 80 degrees. 2. The solar cell insulating substrate according to claim 1, wherein a ratio of the following inclined surface is 5% or more in a projected area ratio (second invention). 3.

A third aspect of the present invention is the solar cell insulating substrate according to the first or second aspect, wherein the metal plate is made of aluminum or an aluminum alloy. The solar cell insulating substrate according to claim 4 is the solar cell insulating substrate according to claim 3, wherein the insulating layer is a layer including an anodized layer formed by anodizing the metal plate. 4 inventions). According to a fifth aspect of the present invention, there is provided the insulating substrate for a solar cell according to the fourth aspect, wherein the surface shape of the metal plate before the anodizing treatment is adjusted using an acid or alkali solution. invention).
The insulating substrate for a solar cell according to claim 6, wherein the metal plate before the anodizing treatment is a hydrochloric acid aqueous solution having a concentration of 0.1% by mass or more;
Concentration of 0.1 wt% or more of nitric acid aqueous solution, or is a solar cell insulating substrate of alternating current electrolysis by the surface shape adjusted to have claim 4, wherein a current density 1~300A / dm ² in a mixed aqueous solution (Sixth invention).

According to a seventh aspect of the present invention, there is provided a method for manufacturing an insulating substrate for a solar cell, comprising: adjusting a surface shape of a metal plate using an acid or alkali solution; and forming an insulating layer on the metal plate. This is a method for manufacturing an insulating substrate for a battery (a seventh invention). The method for manufacturing an insulating substrate for a solar cell according to claim 8, wherein the metal plate is formed by adding a hydrochloric acid aqueous solution having a concentration of 0.1% by mass or more;
After adjusting the surface shape by alternating current electrolysis in a nitric acid aqueous solution having a concentration of 0.1% by mass or more or a mixed aqueous solution thereof at a current density of 1 to 300 A / dm ² , it is necessary to form an insulating layer on this metal plate. This is a method for manufacturing a solar cell insulating substrate, which is a feature of the present invention (eighth invention).

[0012] The above-mentioned mass% is weight%. Hereinafter, mass% (% by weight) is referred to as%.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is embodied, for example, in the following modes. 0.1% concentration of Al (aluminum) alloy plate
A current density of 1 in the above-mentioned aqueous hydrochloric acid solution or aqueous nitric acid solution, or a mixed aqueous solution thereof, for example, a 5% aqueous hydrochloric acid solution.
The surface of the Al alloy plate is adjusted to a surface shape having a surface roughness of Ra (center line average roughness): 0.5 to 200 μm by alternating current electrolysis at 300 A / dm ² .

On the surface of the Al alloy plate after the surface shape adjustment,
An insulating layer having a thickness of 0.5 μm or more is formed. At this time, the surface roughness of the insulating layer is adjusted to Ra: 0.5 to 200 μm.
For example, the Al alloy plate after the surface shape adjustment is anodized to form an anodized film (layer) having a thickness of 10 μm. Then, an anodized layer with a thickness of 10 μm is formed and Ra:
An insulating layer having a surface roughness of 0.5 to 200 μm is formed.

In such a form, the method for manufacturing a solar cell insulating substrate according to the present invention is carried out, and the solar cell insulating substrate according to the present invention is obtained.

In the above-mentioned surface shape adjustment, the inclination angle of the inclined surface of the uneven portion on the surface is 80 degrees or less, and the inclination angle is 30 degrees.
The ratio of the inclined surface not less than 80 degrees and not more than 80 degrees is 5 in projected area ratio.
%, The insulating layer having such a surface shape can be formed, and thus the solar cell insulating substrate according to the second invention is obtained.

Hereinafter, the function and effect of the present invention will be mainly described.

Since a metal plate is extremely hard to break and excellent in flexibility as compared with glass, if the metal plate is provided with electrical insulation, it is hard to break, has flexibility, and is more flexible than a glass substrate. It is a solar cell insulating substrate that can be reduced in weight. The provision of electrical insulation to such a metal plate can be realized by providing an insulating layer on the surface of the metal plate. Therefore, an insulating substrate for a solar cell configured to have an insulating layer on the surface of a metal plate is basically hard to be broken, has flexibility, and can achieve a lighter weight than a glass substrate. It is an insulating substrate.

Furthermore, if the surface of the insulating substrate for a solar cell (that is, the surface of the insulating layer) has a textured surface shape, depending on the surface shape, the light utilization efficiency of the solar cell (hereinafter referred to as light utilization efficiency). ) Can be obtained.

Therefore, the present inventors have prepared an insulating substrate for a solar cell having an insulating layer on the surface of a metal plate, which has various shapes such as the surface shape of the metal plate, the thickness and the surface shape of the insulating layer, and the like. In addition, the light utilization efficiency was mainly examined for them. As a result, it has been found that the light use efficiency increases when the surface roughness of the insulating layer is 0.5 to 200 μm in Ra. It was also found that the thickness of the insulating layer had to be 0.5 μm or more in order to ensure electrical insulation.

In particular, paying attention to the dissolution phenomenon of the Al alloy in the aqueous solution, the surface shape of the Al alloy plate is adjusted by Ra to 0.5 to 200 μm by chemical dissolution or electrochemical dissolution, Insulating layer maintaining the surface shape (ie,
Surface shape similar to this Al alloy plate surface shape (Ra: 0.5 to 20
An insulating layer having a thickness of 0.5 μm) or more, for example, an anodized aluminum alloy plate after the surface shape adjustment is performed to form an anodized layer having a thickness of 0.5 μm or more. It has been found that, when an insulating layer having a surface roughness of up to 200 μm is used as a solar cell substrate, electrical insulation can be ensured and light use efficiency can be increased.

The solar cell insulating substrate according to the present invention has been completed on the basis of the above findings, and is a solar cell insulating substrate having the above-described structure. That is, the insulating substrate for a solar cell according to the present invention is an insulating substrate for a solar cell having an insulating layer on the surface of a metal plate, wherein the thickness of the insulating layer is 0.5 μm or more and the surface of the insulating layer It is characterized in that the roughness is 0.5 to 200 μm in Ra. Therefore, the solar cell insulating substrate according to the present invention,
Has electrical insulation, is hard to crack, has flexibility,
Lighter weight than a glass substrate can be achieved, and light utilization efficiency (light utilization efficiency of a solar cell) can be increased. When the light use efficiency is increased, the short-circuit current value is increased, and as a result, the cell conversion efficiency of the solar cell is improved, and the power generation efficiency is improved. The short-circuit current value is the amount of charge that can be taken out of the battery and is one of the indicators of battery characteristics.

Here, the reason why the thickness of the insulating layer is 0.5 μm or more is that if the thickness is less than 0.5 μm, the electrical insulation becomes unstable and cannot be ensured. The reason that the surface roughness of the insulating layer is Ra 0.5 to 200 μm is Ra0.
When the thickness is less than 5 μm, the light utilization efficiency hardly improves and is insufficient. When the Ra is greater than 200 μm, the light utilization efficiency hardly changes even when Ra is increased. It causes process failures (it causes cell failure etc. due to insufficient mask during film formation)
Because. In addition, Ra0.8 μ
m or more, more preferably Ra 1 μm or more. From the viewpoint of improving the stability of the formation of the photoelectric element laminated film, it is desirable that the Ra be 20 μm or less, and furthermore,
Ra is preferably 10 μm or less.

The surface (Ra 0.5 to 200 μm) of the insulating layer is uneven, and has inclined surfaces at various angles. The portion where the angle of inclination of the concavo-convex portion inclined surface is less than 30 degrees hardly contributes to the improvement of the light use efficiency, and the light use efficiency tends to be improved when the ratio of the inclined surface having the inclination angle of 30 degrees or more is increased. In particular,
When the ratio of the inclined surface having the inclination angle of 30 degrees or more is 5% or more in the projection area ratio, the light use efficiency is further improved. On the other hand, when there is an inclined surface having an inclination angle of more than 80 degrees, the thickness and the like of the photoelectric element laminated film become non-uniform, and the solar cell characteristics tend to deteriorate.
Therefore, it is desirable that there be no inclined surface having an inclination angle of more than 80 degrees on the surface of the insulating layer, and that the ratio of the inclined surface having an inclination angle of 30 degrees or more be 5% or more in terms of the projected area ratio. That is, the inclination angle of the uneven surface inclined surface on the surface of the insulating layer is 80 degrees or less, and the ratio of the inclined surface having an inclination angle of 30 degrees or more and 80 degrees or less in the inclined surface is 5% in projected area ratio. % Is desirable (second invention).

Examples of the surface shape of the insulating layer are shown in FIGS. In the case of FIG. 1, the angle of inclination of the uneven portion inclined surface is 50 degrees. In the case of FIG. 2, the inclination angle of the inclined surface is 40 degrees. FIG.
In the case of, there are a slope of 20 degrees, a slope of 40 degrees, and a slope of 70 degrees. As can be seen from the above, the inclination angle of the uneven portion inclined surface is the angle formed by the uneven portion inclined surface of the insulating layer with respect to the plane of the metal plate below the insulating layer.

Inclination angle: The ratio of the occupied area of the inclined surface of 30 ° or more and 80 ° or less as 5% or more in terms of the projected area ratio means that the surface (having irregularities) of the insulating layer is projected, that is, When the three-dimensional shape (concavo-convex) viewed from above is represented on a plane,
Inclination angle with respect to the product of the total length of the projected portion and the unit width (the area per unit width): The product of the length and the unit width of the portion where the inclined surface of 30 ° to 80 ° is projected (unit width) Per area) is 5% or more. For example, in the case of FIG. 5, the total length the length of the projected portions L _0, the inclination angle: 30 degrees 80 degrees or less inclined surface length of the projected portion is L _1, the inclination angle: 30 degrees The ratio R (%) of the projected area ratio occupied by the inclined surface of not less than 80 degrees is R = [(L ₁ ×
1) / (L ₀ × 1)] × 100 = (L ₁ / L ₀ ) × 100 This is a value (%) obtained by the formula: This R is 5% or more.

In the method of manufacturing an insulating substrate for a solar cell according to the present invention, as described above, after adjusting the surface shape of a metal plate using an acid or alkali solution, an insulating layer is formed on the metal plate. (The seventh invention and the fifth invention). According to this method, the surface shape of the metal plate is 0.5 to 200 μm in Ra.
m, and then the surface shape of the metal plate is similar to the surface shape of the metal plate (Ra: 0.5 to 200 μm).
Can be formed with a thickness of 0.5 μm or more. Therefore, the solar cell insulating substrate according to the present invention can be obtained.

Further, as described above, the surface shape of the metal plate is Ra
At the same time, the inclination angle of the uneven surface inclined surface of the metal plate surface is 80 degrees or less, and the inclination angle in the inclined surface: 30 degrees or more and 80 degrees or less Can be adjusted to a surface shape such that the ratio of the occupied slope surface to the projected area ratio is 5% or more, and then the surface shape of the metal plate is similar to that of the metal plate (Ra: 0.5 to 200 μm).
And an insulating layer having an inclination angle of the uneven surface inclined surface of 30 degrees or more and 80 degrees or less) with a thickness of 0.5 μm or more. By doing so, the solar cell insulating substrate according to the second invention can be obtained.

As the acid solution, nitric acid (0.1 to 72% HN
O ₃ ), hydrochloric acid (0.1-36% HCl), hydrofluoric acid (0.1-48
% HF), a mixture thereof, phosphoric acid (0.1 to 85% H ₃ PO ₄ ), and the like. Examples of the alkaline solution include an aqueous solution of potassium hydroxide (0.1 to 20% KOH) and an aqueous solution of sodium hydroxide (0.1 to 0.1% KOH). -20% NaOH) can be used. For example, when the surface shape of a metal plate is adjusted by chemical dissolution, a mixture of nitric acid (60% HNO ₃ ) 1: hydrochloric acid (36% HCl) 3 in volume ratio (liquid temperature)
30 ° C.), and a metal plate is immersed in this to obtain the surface shape as described above, that is, Ra: 0.5 to 200 μm, Ra: 0.5 to 200 μm, and the inclination angle of the uneven portion inclined surface: 30 A surface shape of not less than 80 degrees and not more than 80 degrees is obtained.

When the surface shape of the metal plate is adjusted by electrochemical dissolution, the treatment can be performed in a shorter time, and the metal plate can be treated with an aqueous solution of hydrochloric acid having a concentration of 0.1% or more, an aqueous solution of nitric acid having a concentration of 0.1% or more, or When the surface shape is adjusted by alternating current electrolysis at a current density of 1 to 300 A / dm ² in these mixed aqueous solutions, the surface shape as described above, that is, the surface shape of Ra: 0.5 to 200 μm or Ra: 0.5 to 200 μm Thus, a surface shape having an inclination angle of the inclined surface of the uneven portion: 30 degrees or more and 80 degrees or less can be obtained (the eighth invention and the sixth invention).

In the above-described electrochemical dissolution method, when the hydrochloric acid concentration of the aqueous hydrochloric acid solution is less than 0.1% or the nitric acid concentration of the aqueous nitric acid solution is less than 0.1%, the dissolution of metals such as Al alloy does not proceed. Ra: It was difficult to obtain a surface shape of 0.5 to 200 μm. The upper limits of the hydrochloric acid concentration and the nitric acid concentration need not be particularly limited from the viewpoint of adjusting the surface shape of the metal plate, but are preferably 15% or less in consideration of easy handling of the liquid. As for the current density, this is 1A /
when less than dm ^2, the effect of electrolysis little, 300A
When the ratio is more than / dm ² , it is difficult to control a uniform surface shape which generates a large amount of heat. Hydrochloric acid concentration: 1.5-10%, nitric acid concentration:
When AC electrolysis was performed at a current density of 15 to 100 A / dm ² in a 1 to 3% mixed aqueous solution, a surface shape particularly effective for improving light use efficiency was obtained.

In the present invention, the insulating layer needs to have insulating properties, but the type thereof is not particularly limited. There are various methods for forming the insulating layer, for example, a method of forming an insulating compound on the surface of the metal plate. The surface shape is Ra: 0.5 to 200 μm, or Ra: 0.5 to 200 μm and Inclination angle: When an insulating layer having a surface shape similar to the surface shape of the metal plate is to be formed on the surface of the metal plate adjusted to a surface shape (texture structure) of 30 degrees or more and 80 degrees or less, the metal is used. It is desirable to adopt an insulating layer forming method that does not significantly affect the plate surface shape (texture structure). The present inventors have studied such an insulating layer forming method, and as a result, when the metal plate is an Al or Al alloy plate,
By forming an insulating layer made of an anodized layer by this anodizing treatment, or further forming an insulating layer made of an insulating material different from the layer on the layer, and using these as insulating layers, It has been found that the characteristics of anodic oxidation can form an insulating layer without significantly affecting the texture structure, and can provide and secure insulating properties.

That is, in the anodic oxidation treatment, the anodic oxidation proceeds from the surface of the Al or Al alloy plate which is in contact with the treatment liquid with the formation of Al oxide in the inward direction thereof. The method of forming an insulating layer is different from the method of forming an insulating layer made of an insulating material different from the anodized layer, and has almost no effect on the surface shape (texture structure) of the Al or Al alloy plate. Al before formation
Alternatively, an insulating layer having a surface shape similar to the surface shape of the Al alloy plate can be formed (fourth invention).

Further, according to the method based on the anodic oxidation treatment, fine irregularities peculiar to the anodic oxidation treatment are superimposed.
When applied to a thin-film solar cell substrate, there is an advantage that an insulating substrate for a solar cell that can further enhance light use efficiency can be obtained.
FIG. 4 shows an example of the anodized layer formed by such anodizing treatment. This is an example of the surface shape after the surface of the Al alloy plate is adjusted to the surface shape as shown in FIG. 1 and anodized to form an anodized layer.

The conditions for the above anodic oxidation treatment are not particularly limited, and as the treatment liquid, for example, a sulfuric acid-based, oxalic acid-based, phosphoric acid-based, or boric acid-based treatment liquid may be used.

The insulating layer can also be obtained by forming a layer made of a compound or resin having no conductivity (hereinafter referred to as a coating insulating layer) by a method such as coating or vapor deposition. In this case, if the insulating layer is thickened, The texture structure on the surface of the metal plate is easily lost (that is, the texture structure hardly remains on the surface of the insulating layer), and it is difficult to form an insulating layer having the same surface shape as the surface shape of the metal plate before the formation of the insulating layer. There is a problem. That is, as described above, the thickness of the insulating layer needs to be 0.5 μm or more in order to secure electrical insulation, and the thicker the insulating layer, the more stable the insulating property can be obtained. Although it is preferable that the thickness of the coating insulating layer is large, the texture structure on the surface of the metal plate is easily lost, and in particular, the texture structure of Ra 10 μm or less may be lost. However, when the metal plate is an Al or Al alloy plate, if a coating insulating layer is formed after forming an insulating layer made of an anodized layer by anodizing treatment, the coating insulating layer is formed directly on the Al or Al alloy plate. In comparison with the case, the thickness of the coating insulating layer necessary for securing the insulating property is about 1/10, and it becomes thinner, so that the influence on the texture structure on the surface of the Al or Al alloy plate is reduced, and before the insulating layer is formed. Al or
An insulating layer having a surface shape similar to the surface shape of the Al alloy plate can be formed (fourth invention). For example, when an anodic oxide layer having a thickness of 10 μm is formed, by forming a coating insulating layer having a thickness of 1 μm, the same insulating properties as when directly forming a coating insulating layer having a thickness of 10 μm can be obtained. In particular, when the coating insulating layer is formed on the anodic oxide layer by the coating method, the coating process becomes uniform due to the effect of capturing the coating material by the pores of the anodic oxide layer, and the adhesion of the coating insulating layer improves, If the coating amount is less than or equal to 1/5 of the oxide layer, extremely high insulation can be realized without affecting the texture structure. Such an effect is particularly remarkable when anodizing treatment is performed by using an aqueous solution of sulfuric acid of 150 to 250 g / L and setting the voltage between the electrodes to 10 to 20 V, and the handling of the solution and the power supply is easy. Such an effect can be sufficiently obtained even when the anodic oxidation treatment is performed under other conditions such as the use of the treatment liquid.

The upper limit of the thickness of the insulating layer is not particularly limited, but generally, an insulating inorganic compound such as an anodic oxide layer is liable to be cracked when it is thick, and utilizes the flexibility characteristic of the metal plate of the substrate. When the anodized layer or a layer containing the anodized layer is used as an insulating layer, the thickness of the anodized layer is desirably 100 μm or less. When the insulating layer is formed of a flexible material such as a resin, the thickness of the insulating layer can be further increased to 100 μm or more as long as a required insulating layer surface shape is obtained.

The type of the metal plate is not particularly limited, and for example, Al or an Al alloy can be used. This Al
When an Al alloy is used, the anodic oxidation treatment as described above has the effect of forming an insulating layer composed of an anodic oxide layer having the same surface shape as the surface shape of the Al or Al alloy plate before forming the insulating layer. In addition, there is the advantage that the solar cell insulating substrate becomes lighter than when iron or stainless steel is used, and thus a lighter solar cell is obtained.In addition, non-ferrous metals other than Al such as magnesium and titanium are used. There is an advantage that a solar cell can be manufactured at a lower cost than in the case where it is provided (third invention).

The Al alloy is not particularly limited. For example, 1000 series, 3000 series, 5000 series, and 6000 series Al alloys can be used. Layers can be formed.

[0040]

EXAMPLE An Al alloy plate (A5052) was subjected to an alternating current electrolysis in a surface shape treatment liquid or by chemical dissolution to adjust the surface shape of the Al alloy plate, and then subjected to anodizing treatment to form the Al alloy plate. An anodized layer was formed on the plate surface. In this way, the solar cell insulating substrates according to Examples 1 to 4 of the present invention were manufactured. After the adjustment of the surface shape of the Al alloy plate and the formation of the anodic oxide layer, a coating insulating layer was formed, thereby manufacturing solar cell insulating substrates according to Examples 5 to 9 of the present invention.

Here, as the surface shape treatment liquid, an aqueous solution containing an acid or an alkali was used. The acid concentration or alkali concentration is as shown in Table 1. In addition, the type of electrolyte in the anodizing treatment, temperature, electrolytic voltage,
The layer (film) thickness of the anodized layer formed by the above anodizing treatment is as shown in Table 1. Table 1 shows the types and methods of forming the covering insulating layer formed on the anodized layer.

On the other hand, by subjecting an Al alloy plate (A5052) to AC electrolysis or chemical dissolution in a surface shape treatment liquid,
After adjusting the surface shape of the Al alloy plate, or after further forming an anodic oxide layer, a coating insulating layer was formed, thereby manufacturing solar cell insulating substrates according to Comparative Examples 1 to 4.
Also, after the Al alloy plate (A5052) was polished or cut to adjust the surface shape, an anodic oxide layer was formed, thereby producing solar cell insulating substrates according to Comparative Examples 5 and 6.

With respect to the solar cell insulating substrates according to Examples 1 to 9 and Comparative Examples 1 to 6 manufactured as described above, the center line average roughness Ra and the inclination angle 30 of the substrate surface (insulating layer surface) were obtained.
The ratio (projected area ratio) R occupied by the uneven surface inclined surface of -80 degrees was measured. Table 1 shows the results. Here, Ra was measured using a surface roughness meter. R was measured by obtaining a profile of the surface of the insulating layer with a surface roughness meter and measuring the profile, and observing the cross-sectional shape of the insulating layer using an optical microscope and a scanning electron microscope.

Further, with respect to the insulating substrates for solar cells according to Examples 1 to 9 and Comparative Examples 1 to 6, the diffuse reflectance was measured, and the light use efficiency was evaluated based on the measured values. In addition, the electrical insulation was measured. Table 1 shows the results.

Here, the electrical insulation was measured by forming an Al electrode having a thickness of 1 μm on the surface of the insulating substrate for a solar cell (the surface of the insulating layer) by sputtering, and then using a parameter analyzer (HP4156 manufactured by Hewlett-Packard Company).
A) The voltage is increased from 0 to 100 V by A), and the surface of the Al electrode and the back surface of the substrate (the surface opposite to the surface having the insulating layer, that is, the surface of the Al alloy plate on which the insulating layer is not formed) The measurement was performed by a method of measuring a leakage current during the measurement. The diffuse reflectance was measured by depositing gold (Au) to a thickness of about 500 mm on the surface of the insulating substrate for a solar cell (the surface of the insulating layer) using a vacuum evaporation apparatus, and then analyzing the spectrum. The measurement was performed by a method of measuring diffuse reflectance using a photometer (UV-240 manufactured by Shimadzu). The diffuse reflectance is a characteristic value indicating the degree of reflection and irregular reflection, and the higher the diffuse reflectance, the higher the light use efficiency, and the better the power generation efficiency.

[0046]

[Table 1]

[0047]

[Table 2]

In the column of light utilization efficiency in Tables 1 and 2, は indicates a diffuse reflectance of 20% or more and is excellent in light utilization efficiency, and Δ indicates a diffuse reflectance of 15% or more and less than 20% and indicates a light utilization. The efficiency is good, and X indicates that the diffuse reflectance is less than 15% and the light use efficiency is poor. In the column of electrical insulation in Tables 1 and 2, ○ indicates a leak current at a voltage of 100 V: less than 10 ⁻⁶ A / mm ^{2, indicating} good insulation. X indicates a leak at a voltage of 100 V. Current: 10 ⁻⁶ A / mm ² or more, indicating poor insulation.

As can be seen from Table 1, the insulating substrates for solar cells according to Comparative Examples 1 to 5 have poor light use efficiency and / or electrical insulation, whereas the insulating substrates according to Examples 1 to 9 of the present invention. The solar cell insulating substrate has excellent light use efficiency and good electrical insulation.

More specifically, the following can be said.
The insulating substrates for solar cells according to Examples 1 to 4 each have an insulating layer formed of only an anodized layer.
The insulating substrate for solar cells according to
SiO ₂ layer is formed by the method (chemical vapor deposition),
In any case, the surface of the insulating layer has a surface shape similar to the surface shape of the Al alloy plate before the formation of the insulating layer, and satisfies the structural requirements of the solar cell insulating substrate according to the present invention. The insulating substrates for solar cells according to Examples 8 and 9 were obtained by forming an Si oxide-based layer by a coating method after forming an anodic oxide layer, and the coating amount was 1 μm on a normal metal surface. However, the coating material did not penetrate into the pores in the anodic oxide layer and did not become a thick layer, so the surface of the insulating layer had almost the same surface shape as the Al alloy plate before the formation of the insulating layer. And satisfies the constituent requirements of the solar cell insulating substrate according to the present invention. for that reason,
Each of the insulating substrates for solar cells according to Examples 1 to 9 has excellent light use efficiency and good electrical insulation.

On the other hand, the device according to Comparative Example 1 does not satisfy the surface shape, which is a constituent requirement of the insulating substrate for a solar cell according to the present invention, so that the light use efficiency is poor and insufficient. The device according to Comparative Example 2 is excellent in light use efficiency, but is poor in electrical insulation because the thickness of the insulating layer is small. In the case of Comparative Example 3, the thickness of the coating insulating layer was made thicker than in the case of Comparative Example 2, so that the electrical insulation was improved and improved. Has become. In the case of Comparative Example 4, since the thickness of the insulating layer was small, the electrical insulation was poor. In the case of Comparative Example 5, since Ra is small, the light use efficiency is poor. The one according to Comparative Example 6 is excellent in light use efficiency, and
Although the electrical insulation is good, Ra is too large, which causes a problem in that a problem occurs in a process of forming a photoelectric element laminated film. In the case of Comparative Example 4, the surface has an inclination angle.
Due to not having an inclined surface of 30 degrees or more, the light use efficiency is small as compared with each embodiment, but there is an effect of surface shape treatment, and if the electric insulation property is improved, it is used. There is no hindrance.

[0052]

The insulating substrate for a solar cell according to the present invention has the above-mentioned structure and functions, and has an electrical insulating property, is resistant to cracking, has flexibility, and has a glass substrate. It is possible to reduce the weight more and to increase the light use efficiency (light use efficiency of the solar cell),
Therefore, it can be suitably used as a substrate for various solar cells, and it is possible to improve the cell conversion efficiency of the solar cell, to enhance the functions such as the power generation efficiency, to improve the quality, and to expand the use of the solar cell. Can be achieved. The method for manufacturing a solar cell insulating substrate according to the present invention can have a remarkable effect that a solar cell insulating substrate having such excellent characteristics can be manufactured and obtained.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the shape of an uneven portion on the surface of an insulating layer and the inclination angle of an inclined surface of the uneven portion.

FIG. 2 is a diagram for explaining the shape of the uneven portion on the surface of the insulating layer and the inclination angle of the inclined surface of the uneven portion.

FIG. 3 is a diagram for explaining the shape of the uneven portion on the surface of the insulating layer and the inclination angle of the inclined surface of the uneven portion.

FIG. 4 is a diagram showing an example of an anodized layer formed by anodizing an Al alloy plate having an uneven surface shape and a surface shape thereof.

[Fig. 5] Inclination angle at irregularities on insulating layer surface: 30 degrees or more
It is a figure for explaining the ratio in the projected area ratio which the inclined surface of 80 degrees or less occupies.

Continuation of the front page (72) Inventor Fumio Uebo 1-5-5 Takatsukadai, Nishi-ku, Kobe, Hyogo Prefecture Inside Kobe Research Institute, Kobe Steel Co., Ltd. (72) Inventor Takuya Masui 1 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Kobe Steel, Ltd. Kobe Institute of Technology, Kobe Steel Co., Ltd. (72) Kohei Suzuki 1-5-5, Takatsudai, Nishi-ku, Kobe, Hyogo Prefecture Kobe Steel, Ltd. Kobe Research Institute F-term (reference) 5F051 BA15 GA02 GA03 GA05 GA06 GA15

Claims (8)

[Claims] 1. A solar cell insulating substrate having an insulating layer on a surface of a metal plate, wherein the insulating layer has a thickness of 0.5 μm.
The insulating substrate for a solar cell as described above, wherein the surface roughness of the insulating layer is 0.5 to 200 μm in center line average roughness (Ra). 2. The projection area, wherein the inclination angle of the inclined surface of the uneven portion on the surface of the insulating layer is 80 degrees or less, and the ratio of the inclined surface having an inclination angle of 30 degrees or more and 80 degrees or less in the inclined surface is the projected area. The insulating substrate for a solar cell according to claim 1, wherein the ratio is 5% or more. 3. The solar cell insulating substrate according to claim 1, wherein the metal plate is made of aluminum or an aluminum alloy. 4. The solar cell insulating substrate according to claim 3, wherein said insulating layer comprises a layer including an anodized layer formed by anodizing the metal plate. 5. The insulating substrate for a solar cell according to claim 4, wherein a surface shape of the metal plate before the anodizing treatment is adjusted by using an acid or an alkali solution. 6. The method according to claim 1, wherein the metal plate before the anodizing treatment is a current solution having a current density of 1 to 300 A in a hydrochloric acid aqueous solution having a concentration of 0.1% by mass or more, a nitric acid aqueous solution having a concentration of 0.1% by mass or more, or a mixed aqueous solution thereof. a / dm ² at the alternating current electrolysis by the surface shape adjusted to have claim 4 solar insulating substrate according. 7. A method for manufacturing an insulating substrate for a solar cell, comprising: adjusting the surface shape of a metal plate using an acid or alkali solution; and forming an insulating layer on the metal plate. 8. The method according to claim 8, wherein the metal plate is a hydrochloric acid aqueous solution having a concentration of 0.1% by mass or more, a nitric acid aqueous solution having a concentration of 0.1% by mass or more, or
A current density of 1 to 300 A /
After adjusting the surface shape by alternating current electrolysis in dm ^2, the method for manufacturing the solar cell insulating substrate and forming an insulating layer on the metal plate.