JP5598986B2 - Solar cell module - Google Patents

Description

  The present invention relates to a solar cell module including a back contact type solar cell having both a positive electrode (P-type semiconductor electrode) and a negative electrode (N-type semiconductor electrode) on the back surface.

  In recent years, solar power generation, which is a power generation system using natural energy, has been rapidly spread. As shown in FIG. 4, a solar cell module for photovoltaic power generation includes a light transmissive substrate 202 disposed on the light receiving side, a back sheet 201 disposed on the back surface side, a light transmissive substrate 202 and a back. A large number of solar cells 203 are arranged between the sheets 201. The solar battery cell 203 is sealed by being sandwiched between sealing materials 204 such as an ethylene / vinyl acetate copolymer (EVA) film.

  Conventionally, in a solar cell module, a large number of solar cells 203, 203... Are electrically connected in series with a wiring member 205 having a width of 1 to 3 mm. Since the solar battery cell 203 is provided with a negative electrode (N-type semiconductor electrode) on the front surface side which is a light receiving surface of the sun and a positive electrode (P-type semiconductor electrode) on the back surface side, The wiring member 205 overlaps the light receiving surface of the battery cell 203, and the area efficiency of photoelectric conversion tends to be reduced. Furthermore, since the wiring member 205 has a structure that wraps around from the front side to the back side of the solar battery cell 203, the wiring member 205 may be disconnected due to a difference in thermal expansion of each member.

  In order to solve these problems, for example, in Patent Documents 1 and 2, both the positive electrode and the negative electrode are installed on the back surface of the solar battery cell, and these electrodes are electrically connected by the circuit layer on the substrate. Contact-type solar cells have been proposed. In the solar cell of this system, it is possible to connect in series on the back surface of the cell, and the light receiving area on the cell surface is not sacrificed, and the reduction of the area efficiency of photoelectric conversion can be prevented. Further, since it is not necessary to have a structure in which the wiring member is wound from the front side to the back side, disconnection due to the difference in thermal expansion of each member can be prevented. In addition, mounting of a photovoltaic cell is performed by connecting an electrode and a circuit layer using a conductive adhesive as a previous stage of sealing a photovoltaic cell with a sealing material.

JP 2009-111122 A JP 2009-224597 A

However, in the back contact type solar cell module, since gaps are formed between the plurality of solar cells in order to reduce the leakage current, a part of the sunlight does not directly enter the solar cells. Pass through the gap. Furthermore, even if it is the light which injected into the photovoltaic cell, the one part will permeate | transmit to the back surface side, without being absorbed by the photovoltaic cell. Therefore, due to the presence of sunlight that does not contribute to power generation in this way, it has been difficult to sufficiently improve the light utilization efficiency.
Moreover, since mounting of the photovoltaic cell is performed using a conductive adhesive, there is a problem that the operation becomes complicated and the production efficiency is lowered.

  This invention is made | formed in view of such a subject, and it aims at providing the solar cell module which can aim at the improvement of production efficiency and light utilization efficiency.

In order to solve the above problems, the present invention proposes the following means.
That is, a solar cell module according to the present invention includes a circuit board in which a circuit layer is formed on the surface of an insulating substrate, a solar battery cell disposed on the surface side of the circuit board and having an electrode on the back surface, A first sealing material interposed between the circuit board and the solar battery cell for sealing the solar battery cell from the back surface side; and a second sealing material for sealing the solar battery cell from the front surface side; The first sealing material includes at least two or more fillers in an insulating resin, and the filler electrically connects the electrode and the circuit layer in the thickness direction of the first sealing material. and conductive filler can be connected, and a said first sealant light incident allows reflective reflective filler, the diameter of the reflective filler is set to be smaller than the diameter of the conductive filler, wherein A metal film is formed on the surface of the reflective filler, and the first The sealing member and the second sealing material, characterized by sealing the entire solar cell.

According to the solar cell module having such characteristics, the conductivity between the electrode and the circuit layer is ensured by the conductive filler in the first sealing material interposed between the solar cell and the circuit layer. . That is, by sandwiching the first sealing material between the solar battery cell and the circuit board, the conductive filler comes into contact with the electrode and the circuit layer, whereby anisotropic conductivity due to the conductive filler is expressed. The electrode and the circuit layer can be electrically connected without causing a short circuit in the cell or the circuit layer.
Moreover, the light that has passed through the solar cells and the light that has passed through the gaps between the solar cells is reflected by the reflective filler in the first sealing material, so that the reflected light is reflected on the back surface of the solar cells. It can be made incident.

Furthermore, in the solar cell module according to the present invention, a metal film may be formed on the surface of the reflective filler.
Thereby, the light which entered in the 1st sealing material can be reflected more reliably, and the said reflected light can be guide | induced to a photovoltaic cell.

In the solar cell module according to the present invention, the diameter of the reflective filler is set in a range of 1 μm to 3 μm.
In order to ensure the light reflectivity by the reflective filler, it is preferable that the diameter of the reflective filler greatly exceeds the wavelength of the light. On the other hand, when the diameter of the reflective filler is set to be larger than 1 μm, the light reflectivity by the reflective filler can be reliably obtained.
On the other hand, in order to ensure conductivity between the electrode and the circuit layer by the conductive filler, it is preferable that the conductive filler is uniformly dispersed. In this respect, when the diameter of the reflective filler is too large, the dispersibility of the conductive filler is hindered. However, in the present invention, since the diameter of the reflective filler is 3 μm or less, the conductive filler is appropriately dispersed. Thus, the conductivity between the electrode and the circuit layer can be reliably obtained.

Furthermore, in the solar cell module according to the present invention, it is preferable that a diameter of the conductive filler is set in a range of 10 μm to 50 μm. Moreover, in the solar cell module which concerns on this invention, it is more preferable that the diameter is set to the range with which the said conductive filler is 10 micrometers-20 micrometers.
Thereby, the electroconductivity of the electrode and circuit layer by an electroconductive filler can be obtained more reliably. That is, the facing distance between the electrode and the circuit layer in the solar cell module is generally 10 to 50 μm at present, but the facing distance tends to become smaller in the future, for example, 10 to 20 μm. It is considered that the size becomes smaller. Therefore, by determining the diameter of the conductive filler in accordance with the facing dimension, it is possible to deal with various solar cell modules.
Moreover, if the diameter of a conductive filler shall be 10 micrometers-20 micrometers, the dispersibility of both fillers is ensured, without interfering with a reflective filler.

  Moreover, in the solar cell module which concerns on this invention, it is preferable that the said base material makes glass fiber impregnate an insulating resin.

According to the solar cell module of the present invention, the electrode and the circuit layer are electrically connected by the conductive filler in the first sealing material interposed between the solar cell and the circuit layer. Therefore, it is not necessary to separately perform the mounting process of the solar battery cell, and the production efficiency can be improved.
In addition, since light that has not contributed to power generation can be guided to the solar battery cell through reflection by the reflective filler in the first sealing material, it is possible to improve light utilization efficiency.

It is a cross-sectional schematic diagram of the solar cell module of the embodiment of the present invention. It is the elements on larger scale of FIG. It is a figure explaining the form of a conductive filler and a reflective filler. It is a cross-sectional schematic diagram of the conventional solar cell module.

Hereinafter, embodiments of the solar cell module of the present invention will be described.
FIG. 1 shows a solar cell module of the present embodiment. The solar cell module 10 includes a circuit board 20, a back sheet 30 disposed on the back side of the circuit board 20, a translucent base material 40 disposed on the front side of the circuit board 20 and forming a light receiving surface, A solar battery cell 50 disposed between the circuit board 20 and the translucent substrate 40 and a sealing layer 60 for sealing the solar battery cell 50 are provided.

The circuit board 20 is configured by integrally laminating a circuit layer 22 on the surface of an insulating base material 21.
As the insulating substrate 21, a plate-shaped member made of a composite material containing fibers and resin, that is, this insulating group in which a prepreg obtained by impregnating or applying a thermosetting resin to a fiber substrate and drying it is used. Examples of the fiber used for the material 21 include glass fiber, aramid fiber, fluorine fiber, polyester fiber, polyarylate fiber, and the like. Of these, glass fiber is preferable from the viewpoints of affinity with thermosetting resin, insulation reliability, and material cost.

  The resin is preferably an addition polymerization type thermosetting resin that cures without generating by-products. Examples of the addition polymerization type thermosetting resin include epoxy resin, unsaturated polyester resin, phenol resin, diallyl phthalate resin, acrylic resin, cyanate resin, cyanate ester resin-epoxy resin, cyanate ester-maleimide resin, cyanide. Acid ester-maleimide-epoxy resin, maleimide resin, maleimide-vinyl resin, bisallylnadiimide resin, and the like can be given. A thermosetting resin may be used individually by 1 type, and may use 2 or more types together.

  The circuit layer 22 is a layer electrically connected to a solar battery cell 50 to be described later, and is laminated on the surface of the insulating base material 21 by pressure bonding. The circuit layer 22 has a circuit pattern for electrically connecting a plurality of solar cells 50 arranged on the insulating base material 21 in series. As a material constituting the circuit layer 22, a material having a low electrical resistance, for example, copper, aluminum, iron-nickel alloy or the like is used. It is preferable that In addition, a conductive polymer can be used as the material of the circuit layer 22.

  The back sheet 30 is a layer for adjusting air permeation, and is laminated and fixed to the back surface of the circuit board 20. The backsheet 30 is made of a material having long-term reliability such as weather resistance and insulation. For example, a fluororesin film, a low oligomer / heat-resistant polyethylene terephthalate (PET) film / polyethylene naphthalate (PEN) film, silica ( SiO2) vapor deposition film, aluminum foil or the like is used.

  The translucent substrate 40 is a member that is disposed on the outermost surface of the solar cell module 10 to form a light receiving surface, and for example, a glass substrate, a transparent resin substrate, or the like is used. Examples of the transparent resin constituting the transparent resin substrate include acrylic resin, polycarbonate, and polyethylene terephthalate.

  The solar battery cell 50 is, for example, a rectangular flat plate, and is an element that generates power by absorbing light. In the present embodiment, the solar battery cell 50 is a plurality of solar batteries along the surface direction of the solar battery module 10. The cells 50 are arranged at predetermined intervals so that the side surfaces of the cells 50 face each other. As the solar cell 50, for example, a single crystal silicon type, a polycrystalline silicon type, an amorphous silicon type, a compound type, or a dye-sensitized type is used. Among these, the single crystal silicon type is preferable in terms of excellent power generation efficiency. Further, the solar battery cell 50 is provided with a plurality of electrodes 51 so as to protrude from the back surface side thereof, and is configured such that electric power generated in the solar battery cell 50 is taken out via the electrodes 51. ing.

  The sealing layer 60 is a layer for sealing the entire solar battery cell 50, and the first sealing material 70 disposed on the back surface side of the solar battery cell 50 and the front surface side of the solar battery cell 50. The second sealing material 80 is arranged.

  As shown in FIG. 2, the first sealing material 70 is composed of a sealing resin 71 and two kinds of fillers, a conductive filler 72 and a reflective filler 73 dispersed and mixed in the sealing resin 71. This is a so-called anisotropic conductive film. The first sealing material 70 is disposed between the solar battery cell 50 and the circuit board 20, whereby the surface of the first sealing material 70 is in contact with the back surface of the solar battery cell 50 and the electrode 51. ing.

  As the sealing resin 71, a synthetic resin having a high light transmittance is used, and it is preferable to use a material having durability such as heat resistance, high temperature resistance, high humidity resistance, and weather resistance, and electrical insulation. As a material that satisfies this condition, for example, a thermoplastic synthetic resin material mainly composed of EVA (ethylene vinyl acetate copolymer) or PVB (polyvinyl butyral) having a vinyl acetate content of 20 to 30% is used. Is done. In addition, synthetic resin materials such as ethylene / (meth) acrylic acid ester copolymers and polyvinylidene fluoride may be used.

  The conductive filler 72 is a particle made of an electrically conductive metal (gold, silver, platinum, nickel, copper, aluminum, zinc, brass, alloys thereof, or the like), and is contained in the first sealing material 70. It has the role which connects the circuit layer 22 and the electrode 51 of the photovoltaic cell 50 in the thickness direction of the said 1st sealing material 70, ie, bears the anisotropic conductive function in the 1st sealing material 70. Yes. The diameter of the conductive filler 72 is preferably set to be approximately the same as or slightly smaller than the thickness of the first sealing material 70, and is, for example, 10 μm to 50 μm depending on the thickness of the first sealing material 70. Is set to a range of 10 μm to 20 μm.

  The reflective filler 73 is a particle made of a material having light reflectivity, and has a role of reflecting light toward the solar battery cell 50 in the first sealing material 70. As the reflective filler 73, particles having a light-reflective metal film (gold, silver, platinum, nickel, copper, aluminum, chromium, titanium, alloys thereof, etc.) formed on the surface, or sealing resin 71 are used. Also, particles formed from a synthetic resin having a large refractive index can be employed. In addition, it is preferable that the diameter of this reflective filler 73 is set to the range of 1 micrometer-3 micrometers.

  As the shapes of the conductive filler 72 and the reflective filler 73, a spherical shape shown in FIG. 3A, an indefinite shape (irregular outer shape) shown in FIG. 3B, and a rectangular parallelepiped shown in FIG. From the shape, the plate shape shown in FIG. 3 (d), the spherical subspecies shape shown in FIG. 3 (e) (the shape in which convex portions are formed on the entire spherical surface), the rod shape shown in FIG. 3 (f), etc. Various shapes can be selected. In particular, as the conductive filler 72, it is preferable to select a spherical shape or a spherical subspecies shape from the viewpoint of electrical connectivity, and as the reflective filler 73, a spherical shape or an indefinite shape is selected from the viewpoint of light reflectivity. It is preferable.

  The first sealing material 70 is configured to include the conductive filler 72 and the reflective filler 73 in the sealing resin 71, whereas the second sealing material 80 is configured to include the conductive filler 72 and the reflective filler 73. It is comprised only from the sealing resin 81, without containing. The second sealing material 80 is disposed between the solar battery cell 50 and the translucent base material 40, whereby the surface of the second sealing material 80 is the surface and side surface of the solar battery cell 50. Touching. As the sealing resin 81 of the second sealing material 80, the same material as the sealing resin 71 of the first sealing material 70 can be used.

Next, a method for manufacturing the solar cell module 10 will be described.
First, a metal foil is bonded onto the insulating base material 21, and the circuit layer 22 is formed by etching the metal foil, whereby the circuit board 20 is obtained. Thereafter, the back sheet 30 is bonded to the back surface of the insulating base material 21 in the circuit board 20.

  Subsequently, each member is laminated | stacked on the surface side of the circuit board 20 in order of the 1st sealing material 70, the photovoltaic cell 50, and the 2nd sealing material 80. FIG. At this time, the electrode 51 of the solar battery cell 50 is in a state of facing the circuit layer 22 with the first sealing material 70 interposed therebetween. In addition, as the 1st sealing material 70, the EVA sheet (sealing resin 71) etc. which contain the electrically conductive filler 72 and the reflective filler 73, etc. are used, for example, and the said 2nd sealing material 80 contains the said filler. No EVA sheet (sealing resin 81) is used. Then, heat treatment is performed while applying pressure from the surface side of the second sealing material 80 using, for example, a flat plate. Thereby, the solar cell 50 is sealed by the sealing layer 60 formed by melting and integrating the sealing resin 71 of the first sealing material 70 and the sealing resin 81 of the second sealing material 80.

  Here, when pressure is applied in the thickness direction to the molten first sealing material 70 by performing the heat treatment while applying pressure as described above, the solar battery cell 50 and the circuit board 20 that are opposed to each other. The conductive filler 72 is in contact with the electrode 51 and the circuit layer 22 at a place where the facing distance is the shortest, that is, at a place where the electrode 51 of the solar battery cell 50 and the circuit layer 22 of the circuit board 20 face each other. Thus, the electrode 51 and the circuit layer 22 are electrically connected in the thickness direction of the first sealing material 70 via the conductive filler 72. In addition, since the said conductive filler 72 is disperse-mixed in the 1st sealing material 70, several adjacent conductive fillers 72 do not contact, and a short circuit arises in the electrode 51 and the circuit layer 22. FIG. There is no.

  Then, the solar cell module 10 of this embodiment can be obtained by joining the translucent base material 40 to the surface of the second sealing material 80 in the sealing layer 60.

  According to the solar cell module 10 having such a feature, the electrode 51 of the solar cell 50 is provided by the conductive filler 72 in the first sealing material 70 interposed between the solar cell 50 and the circuit board 20. And the circuit layer 22 of the circuit board 20 can be secured. That is, by sandwiching the first sealing material 70 between the solar battery cell 50 and the circuit board 20, the conductive filler 72 of the first sealing material 70 contacts the electrode 51 and the circuit layer 22. Thereby, anisotropic conductivity due to the conductive filler 72 is expressed, and the desired electrode 51 and the circuit layer 22 can be electrically connected without causing a short circuit in the electrode 51 or the circuit layer 22.

  Since the electrical connection between the electrode 51 and the circuit layer 22 can be performed simultaneously with the sealing of the solar battery cell 50 by performing the pressure heating process as described above, the mounting of the solar battery cell 50 is performed. There is no need to perform a separate process, and production efficiency can be improved.

  Moreover, since the light which permeate | transmitted the inside of the photovoltaic cell 50 and the light which passed the gap | interval between the several photovoltaic cells 50 can be reflected with the reflective filler 73 in the 1st sealing material 70, the said reflected light Can be made incident on the back surface of the solar battery cell 50. That is, since light that has not contributed to power generation can be guided to the solar battery cell 50, it is possible to improve light utilization efficiency.

Furthermore, in the solar cell module 10 of this embodiment, the light incident into the first sealing material 70 is more efficiently reflected by making the refractive index of the reflective filler 73 larger than the refractive index of the sealing resin 71. Thus, the solar cell 50 can be guided.
Alternatively, when a metal film is formed on the surface of the reflective filler 73, the light incident on the first sealing material 70 can be more reliably reflected, and the reflected light can be efficiently reflected by the sun. It can be led to the battery cell 50.

  Here, in order to ensure the light reflectivity by the reflective filler 73, it is preferable that the diameter of the reflective filler 73 greatly exceeds the wavelength of the light. On the other hand, in this embodiment, since the diameter of the reflective filler 73 is set to be larger than 1 μm, the light reflectivity by the reflective filler 73 can be reliably obtained.

  On the other hand, in order to ensure the conductivity between the electrode 51 and the circuit layer 22 by the conductive filler 72, it is preferable that the conductive filler 72 is uniformly dispersed in the first sealing material 70. In this respect, when the diameter of the reflective filler 73 is too large, the dispersibility of the conductive filler 72 is hindered. However, in this embodiment, the diameter of the reflective filler 73 is 3 μm or less, which is sufficiently larger than the conductive filler 72. Since the conductive filler 72 is appropriately dispersed, the conductivity between the electrode 51 and the circuit layer 22 can be reliably obtained.

  Furthermore, the diameter of the conductive filler 72 is in the range of 10 μm to 50 μm, preferably. Since the thickness is set in the range of 10 μm to 20 μm, the conductivity between the electrode 51 and the circuit layer 22 by the conductive filler 72 can be reliably obtained without hindering the reflection of light by the reflective filler 73. If the diameter of the conductive filler 72 is set in the range of 10 μm to 20 μm, the conductive filler 72 does not interfere with the reflective filler 73 and the dispersibility of both fillers is ensured.

As mentioned above, although embodiment of this invention was described in detail, unless it deviates from the technical idea of this invention, it is not limited to these, A some design change etc. are possible.
For example, as the first sealing material 70, an adhesive containing a conductive filler 72 and a reflective filler 73, that is, an anisotropic conductive adhesive is used, and the second sealing material 80 does not contain the filler. May be used. Also by this, energization with the electrode 51 of the photovoltaic cell 50 and the circuit layer 22 of the circuit board 20 can be easily ensured while securely sealing the photovoltaic cell 50.

  In the embodiment, the first sealing material 70 contains two kinds of fillers, that is, the conductive filler 72 and the reflective filler 73. For example, the first sealing material 70 includes the first sealing material 70. A third filler intended to change the linear expansion coefficient of 70 may be included, that is, the first sealing material 70 includes at least two kinds of conductive filler 72 and reflective filler 73. What is necessary is just to contain the filler.

  When the third filler is contained in the first sealing material 70, the linear expansion coefficient of the first sealing material 70 can be changed by adjusting the content of the third filler. By utilizing this, the separation of the solar battery cell 50 can be prevented by setting the linear expansion coefficient of the first sealing material 70 to an intermediate value between the linear expansion coefficients of the solar battery cell 50 and the circuit board 20. .

DESCRIPTION OF SYMBOLS 10 Solar cell module 20 Circuit board 21 Insulating base material 22 Circuit layer 30 Back sheet 40 Translucent base material 50 Solar cell 60 Sealing layer 70 First sealing material 71 Sealing resin 72 Conductive filler 73 Reflective filler 80 Second sealing material 81 Sealing resin

Claims (5)

A circuit board having a circuit layer formed on the surface of an insulating base;
A solar battery cell disposed on the front side of the circuit board and having an electrode on the back surface;
A first sealing material interposed between the circuit board and the solar battery cell to seal the solar battery cell from the back side;
A second sealing material for sealing the solar battery cell from the surface side;
The first sealing material contains at least two kinds of fillers in the insulating resin,
The filler is
A conductive filler capable of electrically connecting the electrode and the circuit layer in the thickness direction of the first sealing material;
A reflective filler capable of reflecting light incident on the first sealing material;
The diameter of the reflective filler is set smaller than the diameter of the conductive filler,
A metal film is formed on the surface of the reflective filler,
The solar cell module , wherein the entire solar cell is sealed with the first sealing material and the second sealing material . The solar cell module according to claim 1, wherein a diameter of the reflective filler is set in a range of 1 μm to 3 μm. The solar cell module according to claim 1 or 2, wherein a diameter of the conductive filler is set in a range of 10 µm to 50 µm. The diameter of the said conductive filler is set to the range of 10 micrometers-20 micrometers, The solar cell module as described in any one of Claim 1 to 3 characterized by the above-mentioned. The solar cell module according to any one of claims 1 to 4 , wherein the insulating base material is formed by impregnating a glass fiber with an insulating resin.

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