JP2017188620A - Solar cell with connection part and solar cell module - Google Patents

Abstract

Provided are a solar cell with a connecting portion and a solar cell module that are excellent in connectivity between an interconnector and an aluminum electrode. A solar cell includes a plurality of solar cells and an interconnector, the solar cell includes a surface electrode, a photoelectric conversion unit, and a back surface aluminum electrode, and the interconnector includes a front electrode and a first electrode of the first solar cell. 2 are connected to the back surface aluminum electrode of the solar battery cell, the back surface aluminum electrode is connected to the interconnector via the connection portion, the connection portion has an adhesive layer and a copper foil, and the adhesive layer is formed on the back surface aluminum electrode. A solar battery module having a copper foil on the adhesive layer, and having a solar battery cell and a connection part, the solar battery cell having a front electrode, a photoelectric conversion part, and a back surface aluminum electrode A solar cell with a connecting part, wherein the part has an adhesive layer and a copper foil, the adhesive layer is on the back aluminum electrode, the copper foil is on the adhesive layer, and is connected to the interconnector at the connection part. [Selection] Figure 1

Description

  The present invention relates to a solar cell with a connection part and a solar cell module.

  Crystalline silicon solar cells are the mainstream of solar cells currently being produced, but higher efficiency is desired. Among these, development of a PERC (Passivated Emitter Rear Cell) type solar cell and a BSF (Back Surface Field) type solar cell is underway. For example, aluminum is used as the back electrode of these solar cells.

In addition, as a solar cell in which the entire back surface of the solar cell is an aluminum (Al) electrode, for example, aluminum is directly applied and reacted on silicon on the back surface of the n-type silicon solar cell on the back surface of the solar cell to form an emitter layer n-type Al emitter solar cell: TOPCon (Tunnel Oxide Passed Contact) solar cell that forms a passivation film on silicon on the back side of the solar cell and obtains contact with silicon by the tunnel effect; both positive and negative electrodes on the back side of the silicon solar cell Examples include an IBC (Interdigitated Back Contact) solar cell.
Aluminum can be used for the back surface of these solar cells. In particular, when a metal portion other than aluminum is present on the back surface silicon or the insulating film, the metal portion cannot obtain a reaction between silicon and aluminum. For this reason, it is preferable to use aluminum for the entire back surface in terms of conversion efficiency.

In general, electricity generated on the silicon surface (photoelectric conversion unit) of a crystalline silicon solar cell is collected by an electrode called a finger, and further, the solar cells are connected to each other by an interconnector via an electrode called a bus bar. It will be done. Both finger electrodes and bus bar electrodes are usually made of silver. Examples of the interconnector include a copper core material coated with solder.
One end of the interconnector is connected to the front busbar electrode of the solar battery cell, the other end is connected to the back surface silver electrode of the adjacent solar battery cell, and the connected parts are fused and joined to each solar cell. The battery cells are connected in series to form a solar battery module.
The solar cell module formed as described above is sealed with a transparent sealing material such as glass, a transparent plastic, a transparent film, and an ethylene vinyl acetate copolymer, and used as a solar cell.

  On the other hand, a method of connecting a solar battery cell (silicon cell) and an interconnector using an anisotropic conductive film has been proposed. For example, Patent Document 1 includes an adhesive resin composition and a conductive filler contained in the adhesive resin composition in a conductive adhesive that connects a solar cell electrode and a tab wire, and A conductive adhesive using a filament aggregate is described as the conductive filler.

JP 2013-168442 A

However, since solder cannot be fusion bonded with aluminum, when the back electrode of the solar battery cell is only the back aluminum electrode, the back aluminum electrode cannot be connected to the solder of the interconnector. Therefore, generally, a bus bar electrode containing silver is formed on a part of the backside silicon or the insulating film on the backside so that the busbar electrode can be fusion bonded with the solder of the interconnector.
In addition, the present inventors prepared an adhesive resin composition with reference to Patent Document 1, and used this to connect the interconnector and the aluminum electrode (adhesiveness between the interconnector and the aluminum electrode (in the present invention, the above-mentioned Adhesiveness includes adhesion between the interconnector and the aluminum electrode.) Or means electrical conductivity between the interconnector and the aluminum electrode. The same applies hereinafter. Such a composition has low connectivity. I found that there was a case.
Then, an object of this invention is to provide the solar cell module and solar cell with a connection part which are excellent in the connectivity of a back surface aluminum electrode and an interconnector.

As a result of earnest research to solve the above problems, the present inventors connected the back surface aluminum electrode of the solar battery cell and the interconnector via the connection part, and the connection part has an adhesive layer and a copper foil, The inventors have found that a predetermined effect can be obtained by laminating the back surface aluminum electrode, the adhesive layer, the copper foil, and the interconnector in this order, and have reached the present invention.
The present invention is based on the above knowledge and the like, and specifically, solves the above problems by the following configuration.

1. A plurality of solar cells and an interconnector;
The solar battery cell has a front surface electrode, a photoelectric conversion part, and a back surface aluminum electrode,
The interconnector connects the surface electrode of the first solar cell and the back surface aluminum electrode of the second solar cell,
The back surface aluminum electrode is connected to the interconnector via a connecting portion,
The connecting portion has an adhesive layer and a copper foil,
A solar cell module, wherein the adhesive layer is on the back aluminum electrode and the copper foil is on the adhesive layer.
2. 2. The solar cell module according to 1 above, wherein the adhesive layer contains at least one selected from the group consisting of a silicone polymer and a (meth) acrylic polymer.
3. 3. The solar cell module according to 2 above, wherein the adhesive layer further contains conductive particles.
4). 4. The solar cell module according to 3 above, wherein the conductive particles have nickel on the outermost surface.
5. The solar cell module according to any one of 1 to 4, wherein the width of the copper foil is 0.8 to 4.0 times the width of the interconnector.
6). The solar cell module according to any one of 1 to 5, wherein the copper foil has a thickness of 50 µm or less.
7). The solar cell module according to any one of 1 to 6, wherein the solar cell does not have a silver electrode on the back surface.
8). The solar cell module according to any one of 1 to 7, wherein the entire back surface of the solar cell is an aluminum electrode.
9. The solar cell module according to any one of 1 to 8, wherein the interconnector includes a core material, the core material is copper, and the core material is coated with solder.
10. A solar cell and a connection part;
The solar battery cell has a front surface electrode, a photoelectric conversion part, and a back surface aluminum electrode,
The connecting portion has an adhesive layer and a copper foil,
The adhesive layer is on the back aluminum electrode, the copper foil is on the adhesive layer,
A solar cell with a connection part connected to the interconnector at the connection part.

  The solar cell module and the solar cell with connection part of the present invention are excellent in the connectivity between the interconnector and the aluminum electrode.

It is sectional drawing which represents typically the one aspect | mode of the solar cell module of this invention. It is an enlarged plan view which represents typically the one aspect | mode of the light-receiving surface of the photovoltaic cell which comprises the photovoltaic module of this invention, or the photovoltaic cell with a connection part. It is sectional drawing which represents typically the one aspect | mode of the photovoltaic cell which comprises the photovoltaic module of this invention, or the photovoltaic cell with a connection part. It is sectional drawing which represents typically the one aspect | mode of the photovoltaic cell with a connection part of this invention.

The present invention will be described in detail below.
In the present specification, (meth) acrylate represents acrylate or methacrylate, (meth) acryloyl represents acryloyl or methacryloyl, and (meth) acryl represents acryl or methacryl.
In addition, a numerical range expressed using “to” in this specification means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
In this specification, unless otherwise specified, each component can be used alone or in combination of two or more thereof. When a component contains two or more types of substances, the content of the component means the total content of the two or more types of substances.
The present invention is not limited to the attached drawings. In the embodiment of the present invention, a PERC type solar battery cell is described as an example, but the present invention is not limited to the PERC type solar battery cell.
The solar cell module of the present invention and the solar cell with connection portion of the present invention may be collectively referred to as the present invention.
In this specification, having excellent connectivity between an interconnector and an aluminum electrode may simply be excellent in connectivity.
In the present specification, the adhesiveness (including adhesion) between the interconnector and the aluminum electrode by the connecting portion may be referred to as “broadly adhesiveness”. Moreover, the adhesiveness (including adhesiveness) between the back surface aluminum electrode and the copper foil by the adhesive layer may be referred to as “adhesiveness in a narrow sense”.

[Solar cell with connection part]
The solar cell with connection part of the present invention (solar battery cell of the present invention)
A solar cell and a connection part;
The solar battery cell has a front surface electrode, a photoelectric conversion part, and a back surface aluminum electrode,
The connecting portion has an adhesive layer and a copper foil,
The adhesive layer is on the back aluminum electrode, the copper foil is on the adhesive layer,
It is a photovoltaic cell with a connection part connected with an interconnector by the said connection part.

Since the solar battery cell of the present invention has such a configuration, it is considered that a desired effect can be obtained. The reason is not clear, but it is presumed that it is as follows.
Conventionally, a silver electrode and an interconnector of a solar battery cell are bonded by fusion of silver and solder, or are bonded with a conductive film containing, for example, an epoxy resin as a binder resin.
When the conductive film as described above was applied to the adhesion between the aluminum electrode of the solar battery cell and the interconnector, it was revealed that the conductive film could not be bonded to them and the connectivity was low.
The above-mentioned problem of the conductive composition containing an epoxy resin is that when the conductive composition is cured and the aluminum electrode and the interconnector are bonded, the stress caused by the curing shrinkage of the conductive composition causes the aluminum It was speculated that the electrode might be easily peeled off from the solar battery cell.
On the other hand, according to the present invention, since the connecting portion includes the copper foil, the copper foil and the interconnector can be fused and joined by heating, for example. Moreover, since the connection part has an adhesive layer and the adhesive layer has adhesiveness, the adhesive layer can adhere the back surface aluminum electrode and the copper foil (adhesion in a narrow sense). And a connection part can adhere | attach the solar cell which has a back surface aluminum electrode, and an interconnector (adhesion in a broad sense) by joining of the said copper foil and adhesion | attachment of the said adhesion layer.
As described above, the present invention can effectively bond (including adhesion) the back surface aluminum electrode and the interconnector, and can thereby energize the back surface aluminum electrode and the interconnector. From the above matters, the present inventors speculate that the present invention can obtain the above-mentioned effects.
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 4 is a cross-sectional view schematically showing one embodiment of the solar cell with connection part of the present invention.
In FIG. 4, the solar cell 70 with connection portion of the present invention has a solar cell 50 and a connection portion 80.
The solar battery cell 50 has a front surface electrode 15, a photoelectric conversion unit 10, and a back surface aluminum electrode 60.
The surface electrode 15 includes a plurality of bus bar electrodes 20 and finger electrodes 30.
The photoelectric conversion unit 10 includes a p-type silicon semiconductor substrate 36, an n-type impurity layer 34 and an antireflection film or surface passivation layer 32 (hereinafter simply referred to as an antireflection film 32) on the p-type silicon semiconductor substrate 36. May have). The photoelectric conversion unit 10 includes an opening 37 and a back surface passivation layer 38 under the p-type silicon semiconductor substrate 36.
The bus bar electrode 20 penetrates the antireflection film 32 and is electrically connected to the n-type impurity layer 34.
The photoelectric conversion unit 10 and the back surface aluminum electrode 60 are electrically connected through the opening 37.

The connection part 80 includes an adhesive layer 82 and a copper foil 84.
In FIG. 4, the adhesive layer 82 is on the back surface aluminum electrode 60, and the copper foil 84 is on the adhesive layer 82. In the connection portion 80, the adhesive layer 82 has a comb shape, and the copper foil 84 fills the space between the adhesive layers 82.
In the present invention, the adhesive layer may be layered.
In the present invention, the phrase “the adhesive layer is on the back surface aluminum electrode” means that the adhesive layer is on the opposite side of the front surface electrode and the photoelectric conversion portion with the back surface aluminum electrode interposed therebetween.

<< Solar cell >>
The solar cell as a material used for the solar cell with connection part of this invention has a surface electrode, a photoelectric conversion part, and a back surface aluminum electrode. The photoelectric conversion unit generates photogenerated carriers by light incidence. The front surface electrode and the back surface aluminum electrode are a pair of positive and negative electrodes for taking out photogenerated carriers generated in the photoelectric conversion unit.

  Examples of solar cells having an aluminum electrode on the back surface include PERC type solar cells, BSF type solar cells, n-type Al emitter solar cells, TOPCon solar cells, and IBC solar cells.

  The solar cell as a material used for the solar cell with connection part of this invention is not restrict | limited in particular about the manufacturing method. For example, a conventionally well-known thing is mentioned.

<Surface electrode>
In this invention, the electrode on the surface of the photoelectric conversion part of a photovoltaic cell is called surface electrode. Examples of the surface electrode include finger electrodes and bus bar electrodes.

FIG. 2 is an enlarged plan view schematically showing one embodiment of the light receiving surface of the solar battery cell constituting the solar battery module or the solar battery cell with connection portion of the present invention.
In FIG. 2, finger electrodes 30 that collect electricity generated by the photoelectric conversion unit 10 and bus bar electrodes 20 connected to the plurality of finger electrodes 30 are provided on the surface of the photoelectric conversion unit 10 of the solar battery cell 50. Is formed.
The plurality of linear finger electrodes 30 are arranged in parallel to each other at a uniform interval on the surface of the photoelectric conversion unit 10.
The bus bar electrode 20 is arranged in a direction perpendicular to the finger electrodes 30 and further collects current collected by the plurality of finger electrodes 30.

The surface electrode can be formed by combining a plurality of narrow finger electrodes and a wide bus bar electrode in order to make the area that blocks incident light as small as possible. The surface electrode can be formed in a comb shape, for example.
The finger electrodes can be disposed over almost the entire light incident surface of the photoelectric conversion unit. As the finger electrodes, for example, line-shaped electrodes having a width of 100 μm or less, preferably 40 to 80 μm, can be arranged every 2 mm or so.

  A bus-bar electrode can be arrange | positioned at a line form so that it may cross | intersect all the finger electrodes, for example by the width of 0.2-2.0 mm. The number of bus bar electrodes can be appropriately set to an appropriate number in consideration of the size and resistance of the solar battery cell.

The surface electrode can be made of silver, for example.
The surface electrode can be formed, for example, by applying a silver paste containing a cellulose-based resin and glass frit (powdered glass) to the surface of the photoelectric conversion portion and sintering it at 700 to 900 ° C. it can.

<Photoelectric conversion unit>
In the present invention, the photoelectric conversion unit is not particularly limited. For example, the thing similar to the photoelectric conversion part which the said photovoltaic cell has is mentioned.
Specifically, as the photoelectric conversion unit, for example, a p-type silicon semiconductor substrate (a silicon layer doped with an impurity providing p-type) having a thickness of 180 to 250 μm, and a light-receiving surface side (p-type) of the p-type silicon semiconductor substrate. An n-type impurity layer (silicon layer doped with an n-type impurity) having a thickness of 0.3 to 0.6 μm on the silicon semiconductor substrate) and an antireflection film (on the n-type impurity layer). Or a photoelectric conversion portion having a surface passivation layer).
Examples of the antireflection film include a silicon nitride film.

FIG. 3 is a cross-sectional view schematically showing one embodiment of the solar battery cell constituting the solar battery module or the solar battery cell with connection part of the present invention. 3 is a cross-sectional view taken along the line II shown in FIG.
In FIG. 3, the solar battery cell 50 includes a front surface electrode 15, a photoelectric conversion unit 10, and a back surface aluminum electrode 60.
The surface electrode 15 includes a plurality of bus bar electrodes 20 and finger electrodes 30.
The photoelectric conversion unit 10 includes a p-type silicon semiconductor substrate 36, an n-type impurity layer 34, and an antireflection film (surface passivation layer) 32 on the p-type silicon semiconductor substrate 36. The photoelectric conversion unit 10 includes an opening 37 and a back surface passivation layer 38 under the p-type silicon semiconductor substrate 36.
The bus bar electrode 20 penetrates the antireflection film 32 and is electrically connected to the n-type impurity layer 34.
The photoelectric conversion unit 10 and the back surface aluminum electrode 60 are electrically connected through the opening 37.

When the solar cell constituting the solar cell with connection part of the present invention is a PERC type solar cell, a back surface passivation layer and a back surface aluminum electrode are provided on the back surface opposite to the light receiving surface, and a photoelectric conversion unit (silicon semiconductor). And an opening for making contact.
Examples of the back surface passivation layer include a laminated film of an aluminum oxide film and a silicon nitride film.
As a method for forming the opening, for example, a method of forming the opening by performing laser irradiation or etching on the back surface passivation layer on the photoelectric conversion portion (silicon semiconductor) and removing a part of the back surface passivation layer. Can be mentioned.
Examples of the shape of the opening include a linear shape, a curved shape, a broken line shape, and a dot shape. The form is not particularly limited.

<Backside aluminum electrode>
In the present invention, the solar battery cell has an aluminum electrode on the back surface.

  It is preferable from a viewpoint that a photovoltaic cell does not have a silver electrode in the back surface, and is excellent in electric power generation efficiency and economical efficiency.

  The entire back surface of the solar battery cell is preferably an aluminum electrode from the viewpoint of excellent power generation efficiency and economy.

  As a method for forming the aluminum electrode on the back surface, for example, a method for forming an aluminum paste by applying and baking an aluminum paste on the back surface (for example, back surface silicon, back surface passivation layer) of the solar cell as a material, and affixing an aluminum foil And a forming method by vapor deposition of aluminum.

  Especially, the method of forming a back surface aluminum electrode using an aluminum paste is mentioned as one of the preferable aspects. The aluminum paste is not particularly limited. For example, an aluminum paste containing aluminum powder, glass powder and an organic vehicle can be mentioned.

(Aluminum powder)
The aluminum powder preferably has an average particle size of 1 to 10 μm. The average particle size of the aluminum powder can be measured using a laser diffraction particle size distribution meter.
One preferred embodiment of the aluminum powder is spherical.

(Glass powder)
The glass powder is said to have an effect of assisting the reaction between the aluminum powder and silicon and the sintering of the aluminum powder itself. As glass powder, you may contain 1 type selected from the group which consists of Pb, Bi, V, B, Si, Sn, P, and Zn, or 2 or more types. Further, glass powder containing lead, or lead-free glass powder such as bismuth, vanadium, tin-phosphorus, zinc borosilicate, alkali borosilicate, or the like can be used. In view of the influence on the human body, it is desirable to use lead-free glass powder. The glass powder preferably has a softening point of 750 ° C. or lower. If the glass powder has a softening point exceeding 750 ° C., the performance of the passivation film may be significantly impaired when a specific passivation film is used. Moreover, as an average particle diameter of glass powder, 1 micrometer or more and 3 micrometers or less are preferable. Although content of the glass powder contained in an aluminum paste is not specifically limited, It is preferable that they are 0.5 mass part or more and 40 mass parts or less with respect to 100 mass parts of aluminum powder. If the content of the glass powder in the conductive aluminum paste is less than 0.5 parts by mass, the adhesion to the wafer and the passivation film is lowered, and if it exceeds 40 parts by mass, the electrical resistance as an electrode may increase. Because.

(Organic vehicle)
As the organic vehicle, a solvent in which various additives and a resin are dissolved as necessary is used. As the solvent, known solvents can be used, and specific examples include diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether and the like. As various additives, for example, an antioxidant, a corrosion inhibitor, an antifoaming agent, a thickener, a tack fire, a coupling agent, an electrostatic imparting agent, a polymerization inhibitor, a thixotropic agent, an antisettling agent, etc. are used. be able to. Specifically, for example, polyethylene glycol ester compound, polyethylene glycol ether compound, polyoxyethylene sorbitan ester compound, sorbitan alkyl ester compound, aliphatic polycarboxylic acid compound, phosphate ester compound, amide amine salt of polyester acid, polyethylene oxide Series compounds, fatty acid amide waxes and the like can be used. Known resins can be used, such as ethyl cellulose, nitrocellulose, polyvinyl butyral, phenol resin, melanin resin, urea resin, xylene resin, alkyd resin, unsaturated polyester resin, acrylic resin, polyimide resin, furan resin, Thermosetting resin such as urethane resin, isocyanate compound, cyanate compound, polyethylene, polypropylene, polystyrene, ABS resin, polymethyl methacrylate, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl alcohol, polyacetal, polycarbonate, polyethylene terephthalate, Polybutylene terephthalate, polyphenylene oxide, polysulfone, polyimide, polyethersulfone, polyarylate, polyetherether Tons, polytetrafluoroethylene, can be used in combination of two or more kinds of such as silicon resin. The content of the organic vehicle contained in the aluminum paste is not particularly limited, but is preferably 70 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the aluminum powder. This is because if the content of the organic vehicle is less than 70 parts by mass or exceeds 200 parts by mass, the printability of the paste may be deteriorated.

  As a manufacturing method of an aluminum paste, the method of manufacturing an aluminum paste is mentioned by mixing aluminum powder, glass powder, and an organic vehicle with a well-known mixer, for example.

  As a method for forming the back surface aluminum electrode, specifically, for example, an aluminum paste is applied to the entire back surface of the PERC type solar cell in which the opening is formed by screen printing or the like and dried, and then the temperature exceeds 660 ° C. A back surface aluminum electrode can be formed by baking for a short time. Further, at the time of the firing, aluminum and silicon react at a portion where the aluminum paste inside the opening and the photoelectric conversion portion (silicon) are in contact with each other to form a p + layer (p-type layer doped with acceptor impurities at a high concentration). : BSF layer) and an aluminum silicon alloy layer can be formed. Due to the presence of this p + layer, it is possible to obtain a BSF effect that prevents recombination of electrons and improves the collection efficiency of generated carriers.

<< Connection part >>
In the present invention, the connecting portion has an adhesive layer and a copper foil. The copper foil can be fused and joined to the interconnector to which the solar cell with connection part of the present invention can be applied, for example, by heating. The pressure-sensitive adhesive layer can bond the back surface aluminum electrode of the solar battery cell and the copper foil (adhesion in a narrow sense). With the above-described functions of the adhesive layer and the copper foil, the connection portion can bond the back surface aluminum electrode of the solar battery cell and the interconnector (adhesion in a broad sense) and connect them (adhesion and / or electrical connection).

<Copper foil>
The copper foil is a copper film or layer.
The copper foil can be fused and joined to the interconnector.
As the copper foil, one having both sides or one side being flat can be used. Moreover, you may use what processed the unevenness | corrugated surface as a copper foil, for example.

  The thickness of the copper foil is preferably 50 μm or less, and more preferably 8 to 30 μm.

The width of the copper foil can be 0.5 times or more of the width of the interconnector and 0.8 to 4.0 times the width of the interconnector from the viewpoint of superior connectivity. 0.9 to 2.0 times is more preferable.
The width of the copper foil can be 1 to 8 mm.

Moreover, in this invention, you may use the tape-shaped (ribbon-shaped) thing woven with the thin conducting wire as copper foil, for example.
The copper foil is not particularly limited with respect to its production method. For example, a conventionally well-known thing is mentioned.

<Adhesive layer>
The adhesive layer is a layer having adhesiveness.
The adhesive layer is on the back surface aluminum electrode of the solar battery cell (in the solar battery cell, on the opposite side of the front surface electrode and the photoelectric conversion unit across the back surface aluminum electrode).
The pressure-sensitive adhesive layer can bond the back surface aluminum electrode and the copper foil (adhesion in a narrow sense).

(Polymer constituting the adhesive layer)
Examples of the polymer constituting the adhesive layer (polymer contained in the adhesive layer) include silicone-based, (meth) acrylic-based, urethane-based, natural rubber-based, and butyl rubber-based polymers. The polymer may be either rubber or resin (resin), and may be either a homopolymer or a copolymer.
The polymer constituting the adhesive layer is preferably a silicone polymer or a (meth) acrylic polymer.

-Silicone-type polymer The silicone-type polymer which comprises an adhesion layer is a polymer which has polysiloxane as a principal chain skeleton.
One preferred embodiment of the main chain of the silicone polymer is an organopolysiloxane. As an organic group which can be couple | bonded with the said principal chain, the hydrocarbon group which may have a hetero atom is mentioned, for example.
Examples of the hydrocarbon group include an aliphatic hydrocarbon group (which may be linear, branched or cyclic), an aromatic hydrocarbon group such as a phenyl group, or a combination thereof. .
Examples of the hetero atom include an oxygen atom, a nitrogen atom, a sulfur atom, and a halogen. A heteroatom may be bonded to another heteroatom, a hydrogen atom or a carbon atom to form a substituent. The substituent is not particularly limited.

-(Meth) acrylic polymer The (meth) acrylic polymer constituting the adhesive layer is not particularly limited as long as it is a polymer having a repeating unit composed of a monomer having a (meth) acryloyl group. As a monomer which has a (meth) acryloyl group, (meth) acrylic acid ester and (meth) acrylic acid are mentioned, for example.

The (meth) acrylic polymer can have a repeating unit composed of a monomer having an ethylenically unsaturated bond in addition to the repeating unit composed of the monomer. Examples of the monomer having an ethylenically unsaturated bond include olefins such as ethylene and propylene; and aromatic hydrocarbon compounds having a vinyl group such as styrene.
One preferred embodiment of the (meth) acrylic polymer is a partially crosslinked acrylate rubber.

-Urethane-type polymer The urethane-type polymer which comprises an adhesion layer will not be restrict | limited especially if it is a polymer which has a urethane bond.

(Adhesive)
The adhesive layer can be formed using an adhesive. Examples of the adhesive include silicone-based, (meth) acrylic-based, urethane-based, natural rubber-based, and butyl rubber-based adhesives.
The adhesive is preferably a silicone-based or (meth) acrylic-based adhesive.

For example, there are types of pressure-sensitive adhesives that exhibit adhesiveness by drying what is dissolved in a solution, and types that exhibit adhesiveness with reactions such as peroxide crosslinking or hydrosilylation. Any of them can be used in the invention.
Adhesives, for example, can adhere to solar cells and interconnectors by heating, etc., so that the stress due to curing shrinkage can be made extremely small compared to a conductive composition containing an epoxy resin. From the standpoint of superiority and excellent connectivity, one with a little chemical reaction is mentioned as one of preferred embodiments. In addition, the pressure-sensitive adhesive includes, for example, one containing a raw material polymer as a raw material as one of preferable embodiments. The pressure-sensitive adhesive may further contain a solvent and additives described later in addition to the raw material polymer.

-Raw material polymer As an adhesive, what contains raw material polymers, such as a silicone type, (meth) acrylic type, urethane type, a natural rubber type, a butyl rubber type, is mentioned, for example.

The silicone-based raw material polymer contained in the pressure-sensitive adhesive has, for example, a hydrolyzable silyl group, a silanol group, an alkenyl group such as a vinyl group, a Si—H group, or an alkyl group such as a methyl group as a functional group. Can do. The hydrolyzable silyl group is not particularly limited. For example, an alkoxysilyl group can be mentioned.
When the silicone pressure-sensitive adhesive contains, for example, a silicone raw material polymer having a functional group such as a methyl group, a peroxide is used to crosslink the functional group such as a methyl group with the peroxide to form an adhesive layer (silicone polymer ) Can be formed.
One preferred embodiment is that the functional group is bonded to the end of the raw polymer. One polymer molecule can have one or more functional groups.

  The weight average molecular weight of the polymer constituting the raw material polymer or the adhesive layer is preferably 5,000 to 1,000,000, and more preferably 10,000 to 500,000. The said weight average molecular weight is a standard polystyrene conversion value based on the measured value by the gel permeation chromatography (GPC) which uses tetrahydrofuran as a solvent.

  The adhesive layer preferably contains at least one selected from the group consisting of a silicone polymer and a (meth) acrylic polymer from the viewpoint of excellent connectivity and excellent heat resistance.

-Silicone pressure sensitive adhesive The silicone pressure sensitive adhesive is not particularly limited as long as it is a pressure sensitive adhesive containing a silicone raw material polymer as a raw material polymer.
The silicone-based raw material polymer as the raw material polymer is, for example, a silicone polymer having a hydrolyzable silyl group or silanol group; a combination of a silicone polymer having an alkenyl group and a silicone polymer having an Si—H group (for an addition-curable adhesive) And a silicone polymer having a functional group such as a methyl group (in this case, the functional group can be cross-linked with a peroxide).

-(Meth) acrylic pressure-sensitive adhesive The (meth) acrylic pressure-sensitive adhesive is not particularly limited as long as it is a pressure-sensitive adhesive containing a (meth) acrylic raw material polymer as a raw material polymer. For example, the thing similar to the said (meth) acrylic-type polymer which comprises an adhesion layer is mentioned.

-Urethane-based adhesive The urethane-based adhesive is not particularly limited as long as it is a pressure-sensitive adhesive containing a urethane-based material polymer (for example, urethane prepolymer) as a material polymer. The urethane prepolymer is not particularly limited.
The polyisocyanate and polyol that form the urethane prepolymer are not particularly limited. Examples of the polyisocyanate forming the urethane prepolymer include aliphatic polyisocyanates such as hexamethylene diisocyanate and aromatic polyisocyanates such as tolylene diisocyanate. Examples of the polyol forming the urethane prepolymer include polyoxyalkylene polyols such as polyoxypropylene glycol.

(Conductive particles)
Even if the adhesive layer does not contain conductive particles, the back surface aluminum electrode can be energized with the interconnector by connecting the solar cell with connection part of the present invention and the interconnector. From the viewpoint of excellent connectivity and high efficiency of the solar cell module, it is preferable to further include conductive particles.
Examples of the conductive particles include metals such as silver, copper, nickel, solder powder (alloys such as tin-lead, tin-silver-copper, and tin-bismuth); graphite and the like.

  Moreover, as the conductive particles, for example, a filler having a core-shell structure can be used. For example, a polymer or graphite can be used as the core portion. Examples of the shell portion include the above metals. Examples of the filler include styrene beads coated with nickel, graphite coated with nickel, and the like.

  The conductive particles preferably have nickel on the outermost surface, and more preferably graphite coated with nickel.

  The average particle diameter of the conductive particles (when the conductive particles are a filler having a core-shell structure, the average particle diameter of the core portion or the filler) is preferably 5 to 50 μm. In the present invention, the average particle diameter of the conductive particles refers to the particle diameter at 50% cumulative (50% volume cumulative diameter) obtained by measuring the volume-based particle size distribution using a laser diffraction particle size distribution measuring device. As such a laser diffraction type particle size distribution measuring apparatus, for example, an apparatus according to LA-500 (trade name) manufactured by HORIBA, Ltd. may be mentioned.

The content of the conductive particles is preferably 0 to 50% by volume, more preferably 1 to 30% by volume of the pressure-sensitive adhesive, from the viewpoint of excellent electrical conductivity and stability.
The content of the conductive particles is preferably 0 to 70 parts by mass, and more preferably 5 to 50 parts by mass with respect to 100 parts by mass of the pressure-sensitive adhesive from the viewpoint of excellent electrical conductivity and stability.

  The adhesive layer may further contain an additive. Examples of additives include particles other than conductive particles; catalysts such as platinum catalysts and hydrolysis condensation catalysts; tackifiers, surface lubricants, leveling agents, antioxidants, corrosion inhibitors, light stabilizers, ultraviolet absorbers, A polymerization inhibitor, a silane coupling agent, and a filler are mentioned.

  When the material used for forming the adhesive layer further contains the conductive particles or additives in addition to the adhesive, examples of the method for producing the material (adhesive composition) include a roll, a palletary mixer, These can be mixed using a rotation and revolution mixer to obtain a pressure-sensitive adhesive composition.

(Method for producing solar battery cell of the present invention)
As a manufacturing method of the photovoltaic cell of the present invention, for example, a coating step of applying a pressure-sensitive adhesive or a pressure-sensitive adhesive composition to a copper foil to obtain a laminate, and laminating the laminate to cure or laminate the connection portion The method 1 which has the drying hardening process which obtains a body, and the bonding process which bonds the laminated body for connection parts to the back surface aluminum electrode of a photovoltaic cell is mentioned.

-Application | coating process In an application | coating process, the said adhesive or adhesive composition is apply | coated to copper foil, and a laminated body is obtained.
The copper foil used in the coating process is the same as described above.
The method for applying the pressure-sensitive adhesive or the like to the copper foil is not particularly limited.

-Drying and curing step In the drying and curing step, the laminate obtained in the coating step is dried or cured to obtain a laminate for connection part.
The drying or curing temperature is preferably 60 to 200 ° C.

-Bonding process In a bonding process, the laminated body for connection parts obtained at the drying hardening process is bonded to the back surface aluminum electrode of a photovoltaic cell.
In the bonding step, the connection layer laminate is bonded to the back aluminum electrode so that the adhesion layer of the connection layer laminate contacts the back aluminum electrode, and the back surface aluminum electrode and the adhesion layer of the connection layer laminate are Adhesion is performed to manufacture a solar cell with a connection portion.
When heating in the bonding step, the heating temperature is preferably 30 to 80 ° C.
When pressurizing in the bonding step, the pressure is preferably 0.01 to 0.1 MPa.

  Moreover, a commercial item can be used as the laminated body for connection parts used in a bonding process. As a commercial item of the laminated body for connection parts, for example, Takeuchi Kogyo Co., Ltd. copper foil tape CU series (CU-8T, CU-8ST, etc.), 3M metal foil tape CU-18C, CU-9C, 1245, 2245.

  As another manufacturing method of the photovoltaic cell of the present invention, for example, a coating step of applying the pressure-sensitive adhesive or the pressure-sensitive adhesive composition to the back surface aluminum electrode of the solar cell, and then drying the solar cell after the coating step Or the method 2 which has the bonding process which arrange | positions copper foil on the back surface aluminum electrode of the photovoltaic cell of a drying hardening process, and bonds these together is mentioned. The conditions for the coating process, the drying and curing process, and the bonding process in Method 2 can be the same as the conditions for the coating process, the drying and curing process, and the bonding process of Method 1 described above.

The thickness of the pressure-sensitive adhesive layer of the solar battery cell of the present invention is preferably 5 to 80 μm, particularly 10 to 50 μm from the viewpoint that it is excellent in connectivity, has a large adhesive force, and is preferable for producing a solar battery module. More preferred.
The width | variety of the adhesion layer which the photovoltaic cell of this invention has can be 1-8 mm. The width of the adhesive layer may be the same as the width of the copper foil.

It is preferable that the adhesion layer which the photovoltaic cell of this invention has has a high adhesive force in the environment (for example, -40- + 80 degreeC temperature environment) to be used. For this reason, it is preferable that the glass transition temperature of the polymer (resin) which comprises an adhesion layer, or the raw material polymer contained in an adhesive is -40 degrees C or less.
In the present invention, the glass transition temperature is obtained in accordance with JIS K7121: 2012 (plastic transition temperature measurement method) and is measured when the change in the heat flow rate is measured at a temperature increase temperature of 5 ° C./min using a differential thermal analyzer. This is the value obtained by reading the inflection point in the curve obtained.

(Interconnector)
The solar battery cell of the present invention can be connected to an interconnector at a connection portion to form a solar battery module.

The interconnector that can be applied to the solar battery cell of the present invention is not particularly limited. As an interconnector, what has a core material and is coated with a core material is mentioned as one of the preferable aspects, for example.
An example of the core material is copper.
An example of the material for coating the core material is solder. Solder is not particularly limited.
For example, tin-lead solder and lead-free solder can be mentioned.
The thickness of the coating layer for coating the core material is preferably 15 to 45 μm.
The width of the interconnector is preferably 0.8 to 2.0 mm.
The interconnector is not particularly limited with respect to its manufacturing method.

The interconnector can connect the front surface electrode of the first solar battery cell and the back surface aluminum electrode of the second solar battery cell.
The surface electrode connected to the interconnector is preferably a bus bar electrode.
The surface electrode can be connected to one end of the interconnector.
The surface electrode and the interconnector can be connected directly or via an adhesive layer. The adhesive layer is not particularly limited. For example, the adhesive layer can be formed using a composition containing an epoxy resin and a conductive filler.
The back surface aluminum electrode is connected to the other end of the interconnector via the connecting portion.

[Solar cell module]
The solar cell module of the present invention is
A plurality of solar cells and an interconnector;
The solar battery cell has a front surface electrode, a photoelectric conversion part, and a back surface aluminum electrode,
The interconnector connects the surface electrode of the first solar cell and the back surface aluminum electrode of the second solar cell,
The back surface aluminum electrode is connected to the interconnector via a connecting portion,
The connecting portion has an adhesive layer and a copper foil,
The solar cell module has the adhesive layer on the back aluminum electrode and the copper foil on the adhesive layer.

In the solar cell module of the present invention, the number of solar cells is two, or two or more.
Each of the solar cells can be connected in series with another adjacent solar cell via an interconnector.
The number of interconnectors that connect adjacent solar cells is not particularly limited. The number may be 1 to 4.

FIG. 1 is a cross-sectional view schematically showing one embodiment of the solar cell module of the present invention.
In FIG. 1, the solar cell module 90 of the present invention has a plurality of solar cells 50 and an interconnector 40.
The solar battery cell 50 has a front surface electrode 15, a photoelectric conversion unit 10, and a back surface aluminum electrode 60. The surface electrode 15 has a plurality of finger electrodes 30 and a bus bar electrode 20.
The interconnector 41 connects the bus bar electrode 21 of the first solar battery cell 51 and the back surface aluminum electrode 62 of the second solar battery cell 52.
The back surface aluminum electrode 62 is connected to the end portion 44 of the interconnector 41 via the connection portion 80 included in the second connecting portion-equipped solar battery cell 72. The back surface aluminum electrode 62 is electrically connected to the interconnector 41.
The connection part 80 has an adhesive layer and a copper foil.
There is an adhesive layer on the back aluminum electrode 60, and a copper foil on the adhesive layer.
The bus bar electrode 21 is connected to the end 43 of the interconnector 41. The bus bar electrode 21 is electrically connected to the interconnector 41. The surface electrode (bus bar electrode) may be connected to the interconnector through an adhesive layer.
The second connecting portion solar cell 72 and the third connecting portion solar cell 73 are the first connecting portion solar cell 71 and the second connecting portion solar cell 72 and the interconnector 41. The connection can be made through the interconnector 42 in the same manner as the connection through the interconnector 42.
The core material is omitted from the interconnector 40.

The solar battery cell and connection part which the solar battery module of this invention has are the same as the solar battery cell and connection part which the solar battery cell with a connection part of this invention has, respectively. In the solar cell module of the present invention, the solar cell with connection portion of the present invention (solar cell with connection portion 70 in FIG. 1) of the present invention can be used as the solar cell and the connection portion.
The interconnector used for the solar cell module of the present invention is the same as the interconnector that can be applied to the solar cell with connection portion of the present invention.

  In the solar cell module of the present invention, among the plurality of solar cells connected by the interconnector, the end solar cell can be connected to the external output connector via the interconnector.

  The solar cell module of the present invention may be sealed with a sealing material, for example. Examples of the sealing material include a light-transmitting sealing material such as ethylene vinyl acetate copolymer (EVA); a light-transmitting surface protective material such as glass and light-transmitting plastic, and polyethylene terephthalate (PET). Or a combination with a back protective material made of a laminated film having a structure in which an aluminum foil is sandwiched between resin films.

(Method for producing solar cell module of the present invention)
As a manufacturing method of the solar cell module of this invention, it can manufacture using the several photovoltaic cell with a connection part and interconnector of this invention, for example. Specifically, for example, one end of the interconnector is aligned with the bus bar electrode of the solar cell with the first connection portion, and the other end of the interconnector is aligned with the connection portion of the solar cell with the second connection portion. The connecting solar cell and the interconnector are connected. As described above, the solar cells with connection portions connected by the interconnector are heated while being pressurized, and the portions where the interconnectors are in contact with the solar cells with connection portions are fused, and a plurality of solar cells with connection portions and The method which has the joining process of joining an interconnector is mentioned.

-Joining process The temperature in the joining process is preferably 180 to 350 ° C.
The pressure in the joining step is preferably 0.05 to 1.0 MPa.

  The adhesive layer which the solar cell module of this invention has is mentioned as one of the aspects with preferable high adhesive force in the environment (for example, under the temperature environment of -40 to +80 degreeC) used. For this reason, it is preferable that the glass transition temperature of the polymer (resin) which comprises an adhesion layer, or the raw material polymer contained in an adhesive is -40 degrees C or less.

-Sealing process When the solar cell module of this invention is sealed with a sealing material, a sealing process can be further provided after the said joining process.
A sealing process is a process of sealing the solar cell module obtained at the joining process with a sealing material.
The sealing material used in the sealing step is not particularly limited. For example, the thing similar to the above is mentioned.
In the sealing step, the method for sealing the solar cell module obtained in the bonding step with a sealing material is not particularly limited. For example, a conventionally well-known thing is mentioned.

  According to the present invention, the connectivity between a solar battery cell having an aluminum electrode without having a silver electrode on the back surface is excellent. In addition, its excellent connectivity has little change over a long period of time even in an environment from high temperature to low temperature. From this, it is thought that the solar cell module of this invention can maintain the outstanding electroconductivity over a long period, even if it is used under any temperature environment. Thus, it is very important for the efficiency improvement of a solar cell module to be excellent in electroconductivity.

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these.
<Preparation of pressure-sensitive adhesive composition>
Each component shown in the preparation column of the pressure-sensitive adhesive composition in Table 1 below was used in the composition (part by mass) shown in the same table, and these were mixed with a stirrer to produce a pressure-sensitive adhesive composition.

<Preparation of laminate having adhesive layer>
The copper foil (thickness 18 μm, electrolytic copper foil CF-T9FZ-STD, manufactured by Fukuda Metal Foil Powder Co., Ltd.) was slit with the values shown in the copper foil width column in Table 1.
Each pressure-sensitive adhesive composition prepared as described above was applied in layers to one side of a copper foil slit with a predetermined width as described above (application process), and dried or cured under conditions of 80 ° C., and pressure-sensitive adhesive layer A layered product having a thickness was prepared (dry curing step). The thickness of the adhesive layer was 35 μm.

<Preparation of aluminum paste>
7 parts by weight of glass powder and 140 parts by weight of organic vehicle were added to 100 parts by weight of spherical aluminum powder having an average particle size of 5 μm and a purity of 99% or more, and these were mixed in a mixer to prepare an aluminum paste. .

<Manufacture of solar battery cell having back surface aluminum electrode>
(Solar cell)
In manufacturing a solar battery cell having a back surface aluminum electrode, the following PERC type solar battery cell was used as a material.
The PERC type solar cell as a material has an n-type impurity layer having a thickness of 0.3 μm on the light receiving surface side of a p-type silicon semiconductor substrate having a planar dimension of 156 mm × 156 mm and a thickness of 180 μm as a photoelectric conversion part. An antireflection film (passivation film) made of a silicon nitride film on the n-type impurity layer, and an aluminum oxide film and a silicon nitride film stacked on the opposite side of the light-receiving surface of the p-type silicon semiconductor substrate It has a film (back surface passivation layer) and an opening for making contact with the p-type silicon semiconductor substrate. The shape of the opening is linear, the size of the opening is 154 mm long, 50 μm wide, 0.1 μm deep, and the number of openings is 150.
The PERC solar cell has a plurality of silver finger electrodes (formed from a silver paste) and three bus bar electrodes (formed from a silver paste) as surface electrodes.

(Formation of back aluminum electrode)
The aluminum paste prepared as described above was applied to the entire back surface of the PERC type solar battery cell with a thickness of 15 μm by a screen printer and dried. 400 Mesh was used for the screen mesh.
After drying, by firing for 3 seconds under a temperature condition of 700 ° C. or higher, a PERC type solar battery cell having an aluminum electrode on the front surface silver electrode, the photoelectric conversion part and the entire back surface was manufactured. Aluminum and silicon reacted at a portion where the aluminum paste and silicon were in contact with each other to form a p + layer, an aluminum silicon alloy layer, and an aluminum electrode layer.

<Manufacture of solar cells with connection parts>
At the position facing the bus bar electrode on the upper surface of the back surface aluminum electrode of the solar battery manufactured as described above, the laminated body prepared as described above is pasted so that the back surface aluminum electrode and the adhesive layer of the laminated body are in contact with each other. In addition, pressure was applied while heating under the conditions of 30 ° C. and 0.1 MPa to produce a solar cell with a connection part (bonding step). The thickness of the adhesion layer which the photovoltaic cell with a connection part of each Example has was 35 micrometers.

  In Comparative Example 1, an epoxy-based silver paste shown in Table 1 was applied with a width of 1.5 mm on the back surface aluminum electrode of the PERC type solar cell, and cured under conditions of 200 ° C. and 30 minutes. A solar battery cell with a comparative connection part was manufactured. The solar cell with the comparison connection part of the comparative example 1 does not have copper foil.

<Manufacture of solar cell modules>
(Joining process)
One solar cell with connection part and interconnector (1.5 mm width, 230 μm thickness, core material: copper, core material coated with tin-lead solder, manufactured by Marusho Co., Ltd.) and an external output connector manufactured as described above Two (5.0 mm width, 230 μm thickness, core material: copper, core material coated with tin-lead solder, manufactured by Marusho Co., Ltd.) were prepared. The three surface bus bar silver electrodes of the solar cell with connection portion and one end of the three interconnectors were connected to each other, and the other end of the three interconnectors was connected to the first external output connector. Similarly, the copper foil of the solar cell with connection part and one end of three interconnectors were connected to each other, and the other end of the three interconnectors was connected to a second external output connector. The solar cell with connection part connected to the interconnector as described above is heated under pressure at 300 ° C. and 0.2 MPa, and the part where the interconnector is in contact with the solar cell with connection part is fusion bonded. The initial solar cell module was manufactured. The thickness of the adhesive layer included in the initial solar cell module of each example was 35 μm.

(Sealing process)
A solar cell with a connection part connected to an interconnector manufactured as described above, a glass plate and an EVA resin sheet, and an EVA resin sheet and a back sheet (part number QPL, manufactured by Toyo Aluminum Co., Ltd.) different from the above Sandwiched between them (at this time there is an EVA resin sheet on the back sheet, and there is a solar cell with connection part connected to the interconnector on the EVA resin sheet, and the solar cell with connection part connected to the interconnector There is another layer of EVA resin sheet on top, and there is a glass plate on the other EVA resin sheet.) By holding at 140 ° C. and 60 MPa for 10 minutes, between the glass plate and the back sheet The solar battery cell was sealed.

<Evaluation>
(Initial bond strength)
Since the solar cell module manufactured as described above was connected to the connecting portion using the solar cell module after the joining step, a peel test for peeling one of the three interconnectors at an angle of 180 ° was performed according to JIS K 6854-1. The initial adhesive strength was measured in accordance with 1999 under room temperature conditions. The initial adhesive strength is a strength per 1.5 mm (interconnector width). The results are shown in Table 1.

(Initial power generation efficiency of solar cell module)
The solar cell module manufactured as described above is irradiated with pseudo-sunlight generated by a solar simulator (manufactured by Wacom) under the condition of 1 sun, and the current-voltage characteristics of the solar cell module are measured. The initial power generation efficiency of the solar cell module was calculated.

(Maintenance rate of power generation efficiency after wet heat test)
The solar cell module after the sealing step manufactured as described above was subjected to a moist heat resistance test for 200 hours under the conditions of 85 ° C. and 85% HR to obtain a solar cell module after the moist heat resistance test.
Using the solar cell module after the wet heat resistance test manufactured as described above, the current-voltage characteristics are measured in the same manner as the initial power generation efficiency of the solar cell module, and the power generation efficiency of the solar cell module after the wet heat resistance test is calculated. did.

(Maintenance rate of power generation efficiency after wet heat test)
The power generation efficiency maintenance rate of the solar cell module after the wet heat resistance test was determined from the following formula. The results are shown in Table 1.
Power generation efficiency maintenance rate after wet heat resistance test (%) = [(power generation efficiency after wet heat resistance test) / (initial power generation efficiency)] × 100

The detail of each component shown in the preparation column of the adhesive composition of Table 1 is as follows.
Silicone-based adhesive: A mixture of 100 parts by mass of addition-curing adhesive SD4584 (manufactured by Dow Corning) and 0.9 parts by mass of platinum catalyst SRX212 (manufactured by Dow Corning).
The SD4584 used for the silicone-based pressure-sensitive adhesive 1 contains a silicone-based polymer as a raw material polymer.
The glass transition temperature of the cured silicone polymer cured with the silicone adhesive 1 was -91 ° C.

(Meth) acrylic adhesive: 1717DT (manufactured by Soken Chemical Co., Ltd.)
The pressure-sensitive adhesive contains an acrylic ester resin as a raw material polymer. The glass transition temperature of the acrylate resin was −40 ° C. or lower.

-Urethane pressure sensitive adhesive: Urethane pressure sensitive adhesive containing urethane prepolymer synthesized from polyoxypropylene glycol having a weight average molecular weight of 2,000 and 2,4-tolylene diisocyanate, ethyl acetate and ethyl ethyl ketone (Yokohama Rubber) Made).
The glass transition temperature of the urethane prepolymer cured product is -42 ° C.
The urethane prepolymer has a weight average molecular weight of 86,000.

Conductive particle 1 (Ni-G): A surface of graphite having an average particle diameter of 20 μm coated with nickel. The amount of nickel is 70 to 80% by mass of graphite.
Conductive particle 2 (silver): Toyo Chemical Industry silver powder T7001PM, average particle size 9.7 μm

  Epoxy silver paste: A paste containing an epoxy resin and silver. The silver content is 90% by mass with respect to the total amount of the epoxy-based silver paste.

  As is apparent from the results shown in Table 1, Comparative Example 1 in which the connection portion does not have a copper foil has low adhesion strength (initial adhesive strength), initial power generation efficiency, and maintenance efficiency of power generation efficiency, and poor connectivity. . Moreover, the back surface aluminum electrode peeled from the photovoltaic cell as a result of the peeling test of the comparative example 1.

On the other hand, the solar cell module of the present invention was excellent in the connectivity between the interconnector and the aluminum electrode. As a result of the peel test of Examples 1 to 10, the back surface aluminum electrode was not peeled from the solar battery cell, and the adhesive layer was peeled from the back surface aluminum electrode.
When Examples 5, 2 and 4 were compared, the greater the width of the copper foil, the higher the initial adhesive strength and the better the connectivity.
When Examples 2, 6 and 7 were compared, the initial adhesive strength of Example 6 was the highest, and when the pressure-sensitive adhesive layer contained a (meth) acrylic polymer, it was more excellent in connectivity.
Further, when Examples 2, 6 and 7 were compared, the initial power generation efficiency of Example 2 and the power generation efficiency maintenance rate after the wet heat resistance test were the highest, and when the adhesive layer contained a silicone polymer, the connectivity was more excellent.

DESCRIPTION OF SYMBOLS 10 Photoelectric conversion part 15 Surface electrode 20, 21 Bus bar electrode 30 Finger electrode 32 Antireflection film (or surface passivation layer)
34 n-type impurity layer 36 p-type silicon semiconductor substrate 37 opening (alloy layer having a BSF (Back Surface Field) layer)
38 Back surface passivation layers 40, 41, 42 Interconnectors 43, 44 End 50 Solar cell 51 First solar cell 52 Second solar cell 60, 62 Back surface aluminum electrode 70 Solar cell with connection part of the present invention 71 1st solar cell with connection part 72 2nd solar cell with connection part 73 3rd solar cell with connection part 80 connection part 82 adhesive layer 84 copper foil 90 solar battery module of the present invention

Claims (10)

A plurality of solar cells and an interconnector;
The solar battery cell has a front surface electrode, a photoelectric conversion part, and a back surface aluminum electrode,
The interconnector connects the surface electrode of the first solar cell and the back surface aluminum electrode of the second solar cell,
The back surface aluminum electrode is connected to the interconnector via a connection portion,
The connecting portion has an adhesive layer and a copper foil,
A solar cell module in which the adhesive layer is on the back aluminum electrode and the copper foil is on the adhesive layer.   The solar cell module according to claim 1, wherein the adhesive layer contains at least one selected from the group consisting of a silicone polymer and a (meth) acrylic polymer.   The solar cell module according to claim 2, wherein the adhesive layer further includes conductive particles.   The solar cell module according to claim 3, wherein the conductive particles have nickel on the outermost surface.   The solar cell module according to any one of claims 1 to 4, wherein a width of the copper foil is 0.8 to 4.0 times a width of the interconnector.   The solar cell module of any one of Claims 1-5 whose thickness of the said copper foil is 50 micrometers or less.   The solar cell module according to any one of claims 1 to 6, wherein the solar cell does not have a silver electrode on a back surface.   The solar cell module of any one of Claims 1-7 whose whole surface of the back surface of the said photovoltaic cell is an aluminum electrode.   The solar cell module according to any one of claims 1 to 8, wherein the interconnector includes a core material, the core material is copper, and the core material is coated with solder. A solar cell and a connection part;
The solar battery cell has a front surface electrode, a photoelectric conversion part, and a back surface aluminum electrode,
The connecting portion has an adhesive layer and a copper foil,
The adhesive layer is on the back aluminum electrode, the copper foil is on the adhesive layer,
A solar cell with a connection portion connected to the interconnector at the connection portion.