JP2001274428A - Solar cell module - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve overall photoelectric conversion efficiency by reducing the decrease in irradiation light amount to a solar cell even when the irradiation angle of sunlight changes, and to improve metal electrodes in the manufacturing process of a solar cell. Provided is a solar cell module for preventing peeling of a thin film layer. SOLUTION: A protective layer comprising an adhesive layer 72 and a weather-resistant resin layer 73 is provided on a light receiving surface side of a solar cell formed on a film substrate, and an adhesive layer 4 and a reinforcing layer 5 are provided on a non-light receiving surface side. In the solar cell module provided with a protective layer consisting of The cross section in the direction perpendicular to the light receiving surface is assumed to be a substantially semi-cylindrical continuous cross section having a plurality of convex arcs continuous with the light receiving surface, and the light receiving surface side surface of the adhesive layer 72 on the light receiving surface is embossed. It shall be.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to protecting a solar cell formed on a film substrate on both the light-receiving side and the non-light-receiving side of the solar cell in order to seal the solar cell with an electrically insulating protective material. The present invention relates to a solar cell module provided with a layer.

[0002]

2. Description of the Related Art At present, research and development of clean energy are being promoted from the standpoint of environmental protection. Above all, solar cells are attracting attention because of their infinite resources (solar rays) and no pollution. A typical example of a solar cell (photoelectric conversion device) in which a plurality of solar cell elements formed on the same substrate are connected in series is a thin-film solar cell.

Thin-film solar cells are considered to be the mainstream of solar cells in the future because of their thinness, light weight, low production cost, and easy area enlargement. Demand is expanding for business use and general residential use, which are used for such purposes.

Conventional thin-film solar cells use a glass substrate, but research and development of a flexible type solar cell using a plastic film or an insulated metal substrate excellent in weight reduction, workability, and mass productivity have been promoted. ing. Taking advantage of this flexibility, mass production has become possible by roll-to-roll or stepping roll manufacturing methods.

[0005] In the above-mentioned thin-film solar cell, a first electrode layer (lower electrode layer), a photoelectric conversion layer composed of a thin-film semiconductor layer, and a second electrode (transparent electrode layer) are laminated on a flexible electrically insulating film substrate. A plurality of photoelectric conversion elements (or cells) are formed. By repeatedly electrically connecting the first electrode of a certain photoelectric conversion element and the second electrode of the adjacent photoelectric conversion element, the first electrode of the first photoelectric conversion element and the second electrode of the last photoelectric conversion element Required voltage can be output. For example, in order to obtain an AC of 100 V as a commercial power source by converting into an AC by an inverter, the output voltage of the thin-film solar cell is desirably 100 V or more, and actually several tens or more elements are connected in series.

FIG. 5 is a perspective view of a flexible thin-film solar cell using a plastic film as a substrate. The unit photoelectric conversion element 62 formed on the front surface of the substrate 61 and the connection electrode layer 63 formed on the back surface of the substrate 61 are each completely separated into a plurality of unit units, and are formed with their separation positions shifted. For this reason, the current generated in the photoelectric conversion layer 65, which is the amorphous semiconductor portion of the element 62, is first collected in the transparent electrode layer 66, and then through the current collecting hole 67 formed in the transparent electrode layer region, the current on the rear surface is collected. Through the connection electrode layer 63, further through the connection hole 68 for series connection formed outside the transparent electrode layer region of the device in the connection electrode layer region, outside the transparent electrode layer region of the device adjacent to the device. The extended lower electrode layer 64 is reached, and the two devices are connected in series.

As described above, a solar cell is used by connecting a plurality of elements. However, the name differs depending on the cell configuration. Generally, a basic unit of a solar cell is called a unit cell, and a plurality of unit cells are connected in series. Or, a batch deposition unit connected in parallel is referred to as a single cell, and a plurality of such single cells connected in series or parallel with an external power lead wire to form a panel is referred to as a solar cell module. A group of a plurality of such units arranged side by side on a roof or the like is called a solar cell array. In some cases, the above-mentioned single cell is formed in a panel shape and is called a solar cell module.

[0008] As an example of the configuration of a thin-film solar cell module, in order to seal a solar cell formed on a film substrate with an electrically insulating protective material, both the light-receiving side and the non-light-receiving side of the solar cell are required. Is known in which a protective layer is provided. The applicant of the present application has developed a solar cell module and an installation method thereof for the purpose of maintaining the module strength while maintaining light weight and flexibility, and for easy installation and cost reduction. -17262
No. 4 proposes. An example is shown below.

FIG. 6 is a top view of the solar cell module, and FIG.
FIG. 7 is a cross-sectional view along AA in FIG. 6. 6 and 7, the solar cell 1 has an adhesive layer 2 on the sunlight incident side (light receiving surface side) and a weather-resistant protective layer 3 made of a weather-resistant resin layer on its upper surface.
The adhesive layer 4 is laminated on the side opposite to the light incident side (the non-light receiving surface side), and the protective layer composed of the reinforcing layer 5 is laminated thereunder. The adhesive layers 2 and 4, the weather-resistant protective layer 3, and the reinforcing layer 5 are extended to both sides of the solar cell 1 to form a non-power generation area, and a power lead wire for guiding power from the solar cell 1 to the non-power generation area. 6 are connected to the positive and negative poles (not shown) of the solar cell 1 by crossovers 7, respectively. Further, outside thereof, a fixing hole 8 for attaching the solar cell module 20 to a fixing member (not shown) is provided with weatherproof protection. It is opened through the protective layer from the layer 3 to the reinforcing layer 5.

Here, EVA (ethylene vinyl acetate) is used for the adhesive layers 2 and 4, and EVA (ethylene vinyl acetate) is used for the weather-resistant protective layer 3.
A single layer of TFE (ethylene / trifluoroethylene) or a multi-layered structure in which EVA is filled in a glass non-woven fabric is used. And those filled with THV or the like are used.

On the other hand, a power terminal box 9 is adhered on the reinforcing layer 5 or fastened and fixed with screws (not shown), and a connection line 1 is inserted into a hole 11 formed through the adhesive layer 4 and the reinforcing layer 5.
2 is inserted and its end is soldered to the power lead wire 6, and the other end is connected to the conductor core wire 14 of the cable 10 and the screw 13.
To form the solar cell module 20 as a whole.

FIG. 8 is a perspective view, partly in section, of an example of a solar cell array constructed on a roof. The solar cell modules 100 mounted on mounting rails 110 arranged on a base plate 31 are used for the flow of the roof. The cross section in the direction perpendicular to the direction is attached so as to be curved in a bow shape toward the sunlight incident side, forms a valley at the position of the attachment rail 110, and is continuously connected to form the solar cell array 150.

Next, a conventional method for manufacturing a solar cell related to the problem to be solved by the present invention will be described. In the intermediate step, the thin film solar cell is handled in a roll shape together with an EVA adhesive layer on a film formed with a plurality of unit cells. This step will be described below with reference to FIGS.

FIG. 9 is an enlarged and simplified schematic view of a portion having three unit cells in the configuration of FIG. 7. The same components as those in FIG. 9, 70 indicates a unit cell, and schematically shows three photovoltaic elements 62 in the perspective view of FIG. The gap hatching between adjacent unit cells indicates a state in which the space between the unit cells is finally filled with EVA.

The cell film in which a plurality of cells are formed in the state shown in FIG. 5 is overlaid on the EVA film serving as the adhesive layer 2 also for protecting the cells, and this is rolled as shown in FIG. It is rolled up and carried into the next process.
This EVA film has a weak adhesive force in a range of room temperature to 60 degrees, and by this adhesive force, the cell film and the EVA become one roll cell film. . In FIG. 10, 90 indicates the roll cell film, and 50 indicates the core. The roll cell film 90 is rewound in the next step, and other members of the module are assembled.

[0016]

The structure of the conventional solar cell module has the following problems. 1) In order to maximize the photoelectric conversion efficiency of the solar cell module, install the module so that sunlight is incident on the main surface of the thin-film solar cell in the normal direction (the incident angle is 90 degrees). Although it is ideal, the irradiation angle of sunlight varies depending on the season, time, installation location, and the like. From the viewpoint of cost, it is usually difficult to track the movement of the sun. Therefore, in Japan, for example, the sun is usually set at a mid-south solar altitude (about 30 to 40 degrees) near the winter solstice point. Adapted and fixed modules are installed so that the maximum photovoltaic output can be obtained almost mid-south, so that effective output can be obtained throughout the year.

FIG. 4 is a graph showing a change in the amount of photoelectric conversion when the incident angle of sunlight with respect to the light receiving surface is changed.
The photovoltaic power generated when sunlight enters the light receiving surface at a right angle (90 degrees) is defined as 100% (reference), and the ratio to the power is shown. Light not incident on the light receiving surface at right angles is partially reflected on the light receiving surface, and the light incident on the solar cell element is reduced accordingly.

Therefore, when the conventional solar cell module is mounted with the angle of inclination with respect to the ground fixed, the light receiving surface state which is smaller than the power generated during photoelectric conversion when the light receiving surface has an incident angle of 90 degrees is fully irradiated. It often occurs during the time zone. In the installation example of FIG. 8, the entire module is bent in an arc shape so that the light receiving surface can partially obtain an incident angle of 90 °. However, it is effective only for a specific time zone for a partial unit cell. In some cases, there is a problem from the viewpoint of improving the overall photoelectric conversion efficiency of the solar cell module. 2) There are the following problems in the production of solar cells.

As described above, in the case of the conventional manufacturing process in which the cell film and EVA are handled as one roll cell film, since the connection electrode layer (metal electrode thin film layer) 63 in FIG. When rewinding the cell film, the metal electrode thin film layer sometimes peeled off from the cell substrate.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to reduce a decrease in the amount of light applied to a solar cell even when the irradiation angle of sunlight changes. Another object of the present invention is to provide a solar cell module capable of improving overall photoelectric conversion efficiency and preventing peeling of a metal electrode thin film layer in a process of manufacturing a solar cell.

[0021]

In order to solve the above-mentioned problems, the present invention provides a protective layer comprising an adhesive layer and a weather-resistant resin layer on a light receiving surface side of a solar cell formed on a film substrate. Provided, in the solar cell module provided with a protective layer comprising an adhesive layer and a reinforcing layer on the non-light receiving surface side, the protective layer on the light receiving surface side, so as to reduce the decrease in light amount due to fluctuations in sunlight irradiation angle, The cross section of the solar cell module installation inclined surface in a direction perpendicular to the inclination direction is a substantially semi-cylindrical continuous cross section having a plurality of convex arcs continuous on its light receiving surface (claim 1).

[0022] In the solar cell module according to the first aspect, a plurality of the convex arcs are provided corresponding to a unit cell as the smallest solar cell constituting the solar cell module. Is more preferable.

According to the above configuration, even if the irradiation angle of sunlight changes, it is possible to reduce a decrease in the amount of irradiation light to the solar cell. The reason is that even if the irradiation angle of sunlight changes,
Since any surface of the convex arc surface on the forefront of the module forms a surface normal to sunlight, reflected light on the forefront of the module is reduced. Although it does not always enter the cell surface where photoelectric conversion is performed in the normal direction, the cell surface has low reflectivity, and even if it is reflected, there is an amount that it is reflected again by the protective film and returns to the cell side. The photoelectric conversion efficiency is improved.

The second object of the present invention, which is to prevent the metal electrode thin film layer from peeling off in the process of manufacturing a solar cell, can be solved by the invention of claim 3. That is, a protective layer composed of an adhesive layer and a weather-resistant resin layer is provided on the light receiving surface side of the solar cell formed on the film substrate, and a protective layer composed of the adhesive layer and the reinforcing layer is provided on the non-light receiving surface side. In the provided solar cell module, the adhesive layer on the light receiving surface side,
It is assumed that the surface on the light receiving surface side is embossed.

In the solar cell module according to the third aspect, the material of the adhesive layer on the light receiving surface side is ethylene vinyl acetate (EVA);
The embossing is an uneven surface treatment in which a plurality of substantially cylindrical projections are provided on the surface. The diameter and height of the projections are approximately 6% of the thickness of the EVA film. (Preferably, 4 times) of the pitch is preferably twice the diameter.

As described above, when EVA is embossed, the metal electrode thin film layer does not adhere to EVA.
Therefore, when rewinding the roll cell film, the metal electrode thin film layer does not peel off from the cell substrate.

Further, in order to solve both of the problems of improving the overall photoelectric conversion efficiency and preventing peeling, in the solar cell module according to claim 1 or 2, the adhesive layer on the light receiving surface side includes a light receiving surface. The one obtained by embossing the front surface (claim 5) is preferable.

Further, the structure of the solar cell according to the above invention is preferably the structure of claim 6 from the viewpoint of optimizing the manufacturing process. That is, in the solar cell module according to any one of claims 1 to 5, the solar cell comprises a film substrate, in which a lower electrode layer as a metal electrode, a photoelectric conversion layer, and a transparent electrode layer are sequentially laminated. Part, and a connection electrode layer formed on the back surface of the substrate, wherein the photoelectric conversion part and the connection electrode layer are separated from each other in a unit part by displacing a position from each other, and are formed outside the transparent electrode layer formation region. The adjacent unit photoelectric conversion portions separated from each other on the surface are electrically connected in series through a connection hole for a series connection and a current collection hole formed in the transparent electrode layer forming region. And

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In these drawings, the same members as those in the drawings cited in the section of the prior art are denoted by the same reference numerals, and description thereof will be omitted.

(Embodiment 1) FIG. 1 shows an embodiment according to the first, second and fifth aspects of the present invention. FIG. 1 is a schematic diagram in which a portion having three unit cells is enlarged and simplified similarly to FIG. 9, and the difference from FIG. 9 is that the adhesive layer 2 and the weather-resistant protective layer 3 in FIG. At 72 and 7 respectively
As shown by 3, a substantially semi-cylindrical continuous section having a plurality of convex arcs continuous with the light receiving surface is formed. The adhesive layer 2 shown in FIG. 1 has a light-receiving surface that is embossed.

As the adhesive layer 2, EVA is used, and the details thereof will be described in the next embodiment 2 with reference to FIG. 2. However, in FIG. 1, the substantially semi-cylindrical continuous section having the plurality of convex arcs is used. An initially flat weather-resistant protective layer 73 is formed on the embossed EVA layer 82 of FIG.
Are formed by hot pressing in a state where they are stacked. As the weather-resistant protective layer, for example, ETFE having a film thickness of about 25 to 50 μm is laminated using a lamination method in which the layer is handled by vacuum.

According to the solar cell module having the above configuration, since the light receiving surface has a continuous convex arc, even if the irradiation angle of sunlight changes, it is possible to reduce a decrease in the amount of light applied to the solar cell. .

(Embodiment 2) FIG. 2 shows an embodiment according to the third and fourth aspects of the present invention. FIG. 2 shows a state in which the embossed EVA layer 82 is integrated with the unit cell without the weather-resistant protective layer in FIG. This EVA layer 8
2 has a plurality of substantially cylindrical protrusions 85 on the surface, and the diameter d and height h of the protrusions are approximately 6% of the film thickness H of EVA.
And the pitch of the projections is approximately twice the diameter. Examples of the embossed EVA include EVA (EVASAFE-WG-132) manufactured by Bridgestone Corporation.
5) is applicable. By the way, the EVA used in the conventional apparatus is EVA (15295P / AKR / U
F).

The above-mentioned Bridgestone EVA does not fuse at 50 ° C. or less, and fuses at 80 to 110 ° C. on the non-embossed side. Further, the embossed side is fused at 140 to 150 ° C.

FIG. 3 shows a rolled state of the roll cell film of the present invention corresponding to FIG. In the case of the embossed EVA, the metal electrode thin film layer does not stick to the EVA, so that when the roll cell film is rewound, the metal electrode thin film layer does not peel off from the cell substrate.

[0036]

According to the present invention, as described above, a protective layer comprising an adhesive layer and a weather-resistant resin layer is provided on the light-receiving surface side of a solar cell formed on a film substrate, and the non-light-receiving surface is provided. In the solar cell module provided with a protective layer composed of an adhesive layer and a reinforcing layer on the side, the protective layer on the light receiving surface side is a solar cell module installation inclined surface so as to reduce a decrease in the amount of light due to a change in sunlight irradiation angle. The cross section in the direction perpendicular to the tilt direction is assumed to be a substantially semi-cylindrical continuous cross section having a plurality of convex arcs continuous with the light receiving surface, and the adhesive layer on the light receiving surface side is on the light receiving surface side. Since the surface is embossed, it reduces the decrease in the amount of light applied to the solar cell even when the irradiation angle of sunlight changes, thereby improving the overall photoelectric conversion efficiency. Metal electrode thin film layer during manufacturing process It is possible to prevent the release.

[Brief description of the drawings]

FIG. 1 is a schematic partial cross-sectional view of a solar cell module of the present invention having a plurality of continuous convex arcs on a light receiving surface.

FIG. 2 is a schematic partial cross-sectional view of a solar cell module according to the present invention in which a light-receiving surface side surface of a light-receiving surface side adhesive layer is embossed.

FIG. 3 is a schematic sectional view of a roll cell film according to the present invention.

FIG. 4 is a diagram showing a change in a photoelectric conversion amount when a sunlight incident angle is changed.

FIG. 5 is a perspective view of a flexible thin-film solar cell.

FIG. 6 is a top view of a conventional solar cell module.

FIG. 7 is a cross-sectional view of a conventional solar cell module.

FIG. 8 is a partial cross-sectional perspective view of an example of a solar cell array.

FIG. 9 is a schematic partial sectional view of a conventional solar cell module.

FIG. 10 is a schematic sectional view of a conventional roll cell film.

[Explanation of symbols]

2, 72, 82: light-receiving-surface-side adhesive layer, 3, 73: weather-resistant protective layer, 4: non-light-receiving-surface-side adhesive layer, 5: reinforcing layer, 20, 10
0: solar cell module, 61: substrate, 62: photoelectric conversion element, 63: connection electrode layer, 64: lower electrode layer, 65: photoelectric conversion layer, 66: transparent electrode, 67: current collecting hole, 68: connection hole, 70: unit cell, 85: protrusion, 90, 92: roll cell film, 150: solar cell array.

Claims (6)

[Claims] 1. A protective layer comprising an adhesive layer and a weather-resistant resin layer is provided on a light receiving surface side of a solar cell formed on a film substrate, and an adhesive layer and a reinforcing layer are provided on a non-light receiving surface side. In the solar cell module provided with a protective layer, the protective layer on the light receiving surface side, the cross section in the direction perpendicular to the direction of inclination of the solar cell module installation inclined surface, so as to reduce the decrease in the amount of light due to the change in the sunlight irradiation angle, A solar cell module having a substantially semi-cylindrical continuous section having a plurality of convex arcs continuous on its light receiving surface. 2. The solar cell module according to claim 1, wherein a plurality of said convex arcs are provided corresponding to a unit cell as a minimum solar cell constituting the solar cell module. Battery module. 3. A protective layer comprising an adhesive layer and a weather-resistant resin layer is provided on a light receiving surface side of a solar cell formed on a film substrate, and an adhesive layer and a reinforcing layer are provided on a non-light receiving surface side. In a solar cell module provided with a protective layer, the adhesive layer on the light receiving surface side is obtained by embossing the surface on the light receiving surface side. 4. The solar cell module according to claim 3, wherein a material of the adhesive layer on the light receiving surface side is ethylene vinyl acetate (EVA), and the embossing process is performed by:
An uneven surface treatment in which a plurality of substantially cylindrical projections are provided on the surface, and the diameter and height of the projections are approximately 6% of the film thickness of EVA.
A solar cell module having the following dimensions, and the pitch of the projections is approximately twice the diameter. 5. The solar cell module according to claim 1, wherein the adhesive layer on the light receiving surface side is obtained by embossing the surface on the light receiving surface side. 6. The solar cell module according to claim 1, wherein the solar cell is obtained by sequentially laminating a lower electrode layer as a metal electrode, a photoelectric conversion layer, and a transparent electrode layer on a surface of a film substrate. A photoelectric conversion unit, and a connection electrode layer formed on the back surface of the substrate, wherein the photoelectric conversion unit and the connection electrode layer are separated into unit parts by displacing the positions from each other, and outside the transparent electrode layer formation region. The adjacent unit photoelectric conversion portions separated from each other on the surface are electrically connected in series via the formed connection hole for electrical series connection and the current collection hole formed in the transparent electrode layer formation region. A solar cell module comprising a thin-film solar cell comprising: