JP2005150570A - Photo voltaic element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photo voltaic element of less power generation loss and high initial stage power generation efficiency by reducing the shadow loss of the photo voltaic element and enlarging an active area contributing to power generation by making the width of a conductive coating layer of a portion in contact with a photo voltaic body of a cross-section of a wire electrode smaller than a portion of the maximum width of the cross-section of the wire electrode. <P>SOLUTION: The manufacturing method of a photo voltaic element wherein a wire electrode formed of a metallic wire with an unhardened conductive coating layer is arranged in a photo voltaic body via the conductive coating layer has a process for arranging the wire electrode wherein the thickness of the conductive coating layer is at most 0.13 times of the radius of the metallic wire on the photo voltaic body, a process for mounting the metallic bus bar on the wire electrode and a process for performing thermocompression for the arranged metallic wire on the photo voltaic body. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photovoltaic device and a method for manufacturing the same, and more particularly, a photovoltaic device having improved conversion efficiency by reducing shadow loss of the photovoltaic device and increasing an active area contributing to power generation. The present invention relates to an element and a manufacturing method thereof.

  Solar cells using photovoltaic elements are attracting attention as an alternative energy source for solving problems of existing power generation methods such as thermal power generation and hydropower generation.

  As solar cell types, various types of solar cells, such as crystalline solar cells, amorphous solar cells, and compound semiconductor solar cells, have been researched and developed. Although it does not reach the battery, it is easy to increase the area, has a large light absorption coefficient, and has excellent features not found in crystalline solar cells, such as operating with thin films, and is promising for the future. One of the solar cells.

  As a configuration of an amorphous silicon solar cell, for example, a structure in which a back electrode, a semiconductor layer, and a light receiving surface electrode are sequentially laminated on the surface of a conductive substrate made of stainless steel or the like is known. This light receiving surface electrode is formed of, for example, a transparent conductive oxide.

  The resistance value of the transparent conductive film is about 100Ω / □, and normally, in a solar cell, a collector electrode is formed on the light receiving surface electrode in order to lower the resistance value. Patent Document 1 discloses a wire electrode using a metal wire as an example of such a collecting electrode. Since the wire electrode is provided on the light incident surface side of the solar cell, its area becomes a so-called shadow loss, and the active area contributing to power generation of the solar cell is reduced.

Japanese Patent Application Laid-Open No. 08-236796

  A photovoltaic element obtained by thermocompression bonding the above-described wire electrode 102 on the photovoltaic body 101 is shown in FIG. As shown in FIG. 8, the uncured outermost conductive coating layer 103 a extends over the light receiving surface of the photovoltaic body 101, and the width of the portion of the cross section of the wire electrode 102 in contact with the photovoltaic body 101 is the wire electrode 102. As a result, the active area contributing to power generation is reduced.

  In view of the above problems, the present invention is to reduce the width of the conductive coating layer in the portion in contact with the photovoltaic body in the cross section of the wire electrode smaller than the widest portion in the cross section of the wire electrode, An object of the present invention is to provide a photovoltaic device and a method for manufacturing the photovoltaic device that reduce shadow loss of the photovoltaic device, increase an active area that contributes to power generation, reduce power generation loss, and have high initial power generation efficiency. .

  As a result of intensive research and development to solve the above-mentioned problems, the present inventor can reduce the power generation loss of the photovoltaic element and increase the initial power generation efficiency. It has been found that this is an effective method.

  In the present invention, in the method of manufacturing a photovoltaic element in which a wire electrode made of a metal wire having an uncured conductive coating layer is disposed on a photovoltaic body via the conductive coating layer, A step of disposing the wire electrode on the photovoltaic element, the covering layer having a thickness of 0.13 times or less the radius of the metal wire; and placing the metal bus bar on the wire electrode; A method for manufacturing a photovoltaic device, comprising the step of thermocompression bonding the disposed metal wire onto the photovoltaic body.

  By having a step of disposing on the photovoltaic body a wire electrode in which the thickness of the conductive coating layer is not more than 0.13 times the radius of the metal wire, the section of the wire electrode in contact with the photovoltaic body A photovoltaic device can be produced in which the width of the conductive coating layer is smaller than the widest portion of the wire electrode.

  In addition, the method includes the step of disposing the wire electrode on the photovoltaic body, wherein the conductive coating layer has a thickness of 0.027 times or more the radius of the metal wire. Is the method.

  The conductive coating layer has a step of disposing a wire electrode having a thickness of 0.027 times or more of the radius of the metal wire on the photovoltaic body, so that the conductive coating layer can connect the photovoltaic element and the wire electrode. A function as an adhesive layer to be bonded can be sufficiently achieved.

  A wire electrode made of a metal wire having at least two conductive coating layers and having an uncured outermost conductive coating layer is disposed on the photovoltaic element via the conductive coating layer. In the photovoltaic device manufacturing method, the thickness of the conductive coating layer of the outermost layer is not more than 0.13 times the sum of the thickness of the conductive coating layer other than the outermost layer and the radius of the metal wire. A step of disposing a wire electrode on the photovoltaic member, a step of placing the metal bus bar on the wire electrode, and a step of thermocompression bonding the disposed metal wire on the photovoltaic member. It is a manufacturing method of the photovoltaic element characterized by having.

  In the case where a wire electrode having at least two conductive coating layers is disposed on a photovoltaic element, the conductive coating layer having a thickness of at least the outermost conductive coating layer out of the conductive coating layers other than the outermost layer. The wire electrode having a thickness of 0.13 times or less of the sum of the thickness of the metal wire and the radius of the metal wire is disposed on the photovoltaic body, whereby the outermost layer of the wire electrode cross section in contact with the photovoltaic body It is possible to manufacture a photovoltaic device in which the width of the coating layer is smaller than that of the widest portion of the wire electrode.

  In addition, the wire electrode having a thickness of the conductive coating layer of the outermost layer that is not less than 0.027 times the sum of the thickness of the conductive coating layer other than the outermost layer and the radius of the metal wire on the photovoltaic element. A method for producing a photovoltaic device, comprising the step of:

  In the case where a wire electrode having at least two conductive coating layers is disposed on a photovoltaic element, the conductive coating layer having a thickness of at least the outermost conductive coating layer out of the conductive coating layers other than the outermost layer. A wire electrode having a thickness of 0.027 times or more of the sum of the thickness of the metal wire and the radius of the metal wire is disposed on the photovoltaic body, so that the outermost conductive coating layer is formed on the photovoltaic body and the wire electrode. Can sufficiently function as an adhesive layer for adhering.

  Further, in the photovoltaic element in which the wire electrode made of a metal wire having a conductive coating layer is disposed, the width of the conductive coating layer in a portion in contact with the photovoltaic body in the cross section of the wire electrode is It is a photovoltaic element characterized by being smaller than the widest part of the cross section of a wire electrode.

  According to the present invention, in the photovoltaic element in which the wire electrode is disposed, the width of the conductive coating layer in the portion in contact with the photovoltaic body in the cross section of the wire electrode is the largest portion in the cross section of the wire electrode. The shadow loss of the photovoltaic element can be reduced and the active area contributing to power generation can be increased.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  First, the photovoltaic element 604 is shown in FIG. FIG. 1 is a schematic cross-sectional view of a photovoltaic element 604, which is an example showing a wire electrode that is thermocompression bonded onto the photovoltaic element of the present invention. In FIG. 1, 102 is a wire electrode, and 101 is a photovoltaic element. In the present invention, the wire electrode 102 is formed by coating the periphery of the metal wire 104 with the conductive coating layer 103.

Below, explanation is added for each item.
(Photovoltaic body)
The photovoltaic element according to the present invention is a substrate having a photoelectric conversion function. As the photoelectric conversion layer, single crystal, thin film single crystal, polycrystal, thin film polycrystal, and amorphous can be used.

  Here, as a typical example, the amorphous silicon-based photovoltaic element 101 will be described in detail. Cross-sectional views of an example thereof are shown in FIGS.

  5A to 5C are schematic cross-sectional views of an amorphous silicon-based photovoltaic element 101 of a type in which light is incident from the surface opposite to the substrate 501. 5A to 5C, 501 is a substrate, 502 is a lower electrode, 503 is an n-type semiconductor layer, 504 is an i-type semiconductor layer, 505 is a p-type semiconductor layer, and 506 is an upper electrode made of a transparent conductive film. Represents.

  In the case of the thin film photovoltaic element 101 such as amorphous silicon, the substrate 501 is a member that mechanically supports the semiconductor layers 503, 504, and 505, and may be conductive or electrically insulating. More preferably, a conductive material is used because it is also used as an electrode. The substrate 501 is required to have heat resistance that can withstand the heating temperature when the semiconductor layers 503, 504, and 505 are formed.

Examples of the conductive material include metals such as Fe, Ni, Cr, Al, Mo, Au, Nb, Ta, V, Ti, Pt, Pb, and Ti, or alloys thereof such as thin plates such as brass and stainless steel, and Examples of the electrically insulating material include polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide, and epoxy. Films or sheets of heat-resistant synthetic resin or composites thereof with glass fibers, carbon fibers, boron fibers, metal fibers, etc., and thin metal plates of these metals, metal thin films of different materials on the surface of resin sheets, etc. and / or SiO 2
, Si3 N4, Al2 O3, AlN, etc., which are subjected to surface coating treatment by sputtering, vapor deposition, plating, etc., and glass, ceramics and the like.

The lower electrode 502 is one electrode for taking out the electric power generated in the semiconductor layers 503, 504, and 505, and the semiconductor layer 503 is required to have a work function that forms an ohmic contact. Examples of materials include Al, Ag, Pt, Au, Ni, Ti, Mo, W, Fe, V, Cr, Cu, nichrome, SnO 2.
A so-called metal body or alloy such as In 2 O 3, ZnO, or ITO, a transparent conductive oxide (TCO), or the like is used. The surface of the lower electrode 502 is preferably smooth, but may be textured when causing irregular reflection of light. In addition, when the substrate 501 is conductive, the lower electrode 502 is not necessarily provided. The lower electrode 502 can be formed by a known method such as plating, vapor deposition, or sputtering.

  The amorphous semiconductor layer has not only a single configuration (FIG. 4 (a)) in which the n layer 503, the i layer 504, and the p layer 505 are set as one set (FIG. 4A), but also a double configuration in which two or three pin junctions or pn junctions are stacked ( FIG. 4B) and a triple configuration (FIG. 4C) are also preferably used. In particular, as a semiconductor material constituting the i layer 504, in addition to a-Si, so-called group IV and group IV alloy amorphous semiconductors such as a-SiGe and a-SiC can be given.

  As a method for forming the amorphous semiconductor layer, for example, a known method such as an evaporation method, a sputtering method, a high-frequency plasma CVD method, a microplasma CVD method, an ECR method, a thermal CVD method, or an LPCVD method is used as desired. As the film forming apparatus, a batch type apparatus or a continuous film forming apparatus can be used as desired.

The upper electrode 506 made of a transparent conductive film is necessary when the sheet resistance is high like amorphous silicon, and needs to be transparent in order to be positioned on the light incident side. As a material of the upper electrode 46, for example, SnO 2
, In2O3, ZnO, CdO, CdSnO4
And metal oxides such as ITO.

Moreover, all the structures which implement | achieve the same function irrespective of said structure can be included.
(Photovoltaic element)
A collector electrode (wire electrode) and a metal bus bar, which will be described later, are attached to the photovoltaic element so that electric power can be taken out from the photovoltaic element.
(Wire electrode)
Examples of the wire electrode according to the present invention include those shown in FIG.

  The wire electrode 102 in FIG. 2A is a case where the metal wire 104 is coated with one type of conductive coating layer 103. The wire electrode 102 in FIG. 2B is a case where the metal wire 104 is coated with two types of conductive coating layers 103, that is, the first coating layer 103a and the second coating layer 103b.

The metal wire 104 is preferably one that is industrially stably supplied as a wire. As a material of the metal wire 104, it is desirable to use a metal having a specific resistivity of 10 −4 Ωcm or less.
For example, materials such as copper, silver, gold, platinum, aluminum, molybdenum, and tungsten are preferably used because of their low electric resistance. Of these, copper, silver, and gold have low electrical resistance and are desirable. In addition, a thin metal layer may be formed on the surface of the metal wire 104 for the purpose of preventing corrosion, preventing oxidation, improving adhesion with a conductive resin, improving electrical conduction, and the like. Examples of the metal layer provided on the surface of the metal wire 104 include noble metals that are not easily corroded, such as silver, palladium, an alloy of silver and palladium, and gold, and metals having good corrosion resistance such as nickel and tin. Among these, gold, silver, and tin are less susceptible to humidity and the like, and thus are preferably used as a metal layer. As a method for forming a metal layer provided on the surface of the metal wire 104, for example, a plating method or a cladding method is preferably used.

  The cross-sectional shape of the metal wire 104 is appropriately selected as desired. The radius of the metal wire 104 is a value selected by designing so that the sum of the electrical resistance loss and the shadow loss is minimized. Specifically, for example, a copper wire having a radius of 12.5 μm to 0.5 mm for enameled wire shown in JIS-C-3202 is preferably used. More preferably, the photovoltaic element 604 with high photoelectric conversion efficiency can be obtained by setting the radius to 12.5 μm or more and 100 μm or less. If the thickness is smaller than 12.5 μm, the metal wire 104 is easily cut and difficult to manufacture, and the electrical loss increases.

  The metal wire 104 is formed by forming a desired radius using a known wire drawing machine. The metal wire 104 that has passed through the wire drawing machine is hard, but the easiness of elongation, the easiness of bending, and the like may be annealed by a known method according to desired characteristics to make it soft.

  On the other hand, the conductive coating layer 103 shown in FIG. 2A is a single-layer coating layer, and is formed of a thermosetting conductive adhesive or a thermoplastic conductive adhesive. These have the function of mechanically and electrically connecting the wire electrode 102 and the photovoltaic element 101 by a thermocompression bonding process. The conductive adhesive constituting the conductive coating layer 103 is left in an uncured state after coating, and is processed after an adhesion process. Preferably, it is desirable to make it semi-cured to such an extent that it has an adhesive function.

  The conductive coating layer 103 shown in FIG. 2B is a two-layer coating layer, and includes a first coating layer 103a and a second coating layer 103b. The first covering layer 103a is formed of a thermosetting conductive adhesive, and protects the metal wire 104 and mechanically and electrically connects it. Further, it has a function of preventing migration due to the metal wire 104 and suppressing a current flowing from the wire electrode 102 into the defective portion of the photovoltaic element 101. The second covering layer 103b is also formed of a thermosetting conductive adhesive and has a function of mechanically and electrically connecting the wire electrode 102 and the photovoltaic element 101 by a thermocompression bonding process. The conductive adhesive constituting the second coating layer 103b, which is the outermost layer, is left in an uncured state after coating, and is processed after an adhesion process. Preferably, it is desirable to make it semi-cured to such an extent that it has an adhesive function.

  The conductive coating layer 103 is made of a conductive adhesive and is obtained by dispersing conductive particles and a polymer resin.

The conductive particles are pigments for imparting conductivity, and examples of the material include carbon black, graphite, and In 2.
O 3, TiO 2, SnO 2, ITO, ZnO, and an oxide semiconductor material obtained by adding an appropriate dopant to the above materials are preferably used. Since these materials have a low migration property, they can be used in the photovoltaic element 101 having a thin film semiconductor layer, for example.

  As the polymer resin, a resin that can easily form a coating film on the metal wire 104, has excellent workability, has flexibility, and has excellent weather resistance is preferable. Examples of the polymer resin having such characteristics include a thermosetting resin and a thermoplastic resin.

  As the thermosetting resin, for example, urethane, epoxy, phenol, polyvinyl formal, alkyd resin, or a resin obtained by modifying these can be cited as a suitable material. In particular, urethane resin, epoxy resin, and phenol resin are used as insulating coating materials for enameled wires, and flexibility is an excellent material in terms of productivity.

  Examples of suitable thermoplastic resins include butyral, phenoxy, polyamide, polyamideimide, melamine, butyral, acrylic, styrene, polyester, and fluorine. In particular, butyral resin, phenoxy resin, polyamide resin, and polyamideimide resin are excellent materials in terms of flexibility, moisture resistance, and adhesiveness, and are preferably used as the material of the wire electrode 102.

  In the conductive adhesive, for example, an additive such as a coupling agent may be mixed for the purpose of improving adhesion to a metal.

  The conductive particles and the polymer resin are mixed at a suitable ratio. However, when the conductive particles are increased, the stability as a coating film is deteriorated. Further, when the polymer resin is increased, the contact between the conductive particles becomes poor and the resistance is increased. Therefore, a good ratio is appropriately selected depending on the polymer resin to be used, conductive particles, and desired physical property values. Specifically, a favorable conductive coating layer 103 can be obtained by setting the conductive particles to 5 volume% to 95 volume%.

  A cross-sectional view of the wire electrode 102 after thermocompression bonding is shown in FIG.

When the wire electrode 102 is thermocompression-bonded on the photovoltaic body 101, the outermost conductive coating layer 103b of the wire electrode 102 spreads on the photovoltaic body 101 as shown in FIG.
Becomes a shadow loss of the photovoltaic element 604. Therefore, in order to increase the active area contributing to power generation and reduce power generation loss, the width t1 of the outermost conductive coating layer 103b in contact with the photovoltaic element 101 after thermocompression bonding.
Must be smaller than the largest width t 2 of the cross section of the wire electrode 102.

In order to make the wire electrode 102 after thermocompression bonding have the above-mentioned shape, as shown in FIG. 4, the radius of the metal wire 104 is D, and the thickness of the uncured outermost conductive coating layer 103b is d1.
When the thickness of the other conductive coating layer 103a is d2,
d1 = k × (D + d2)
It is desirable that k in the relational expression expressed by can be 0.13 or less. Preferably, k is 0.027 or more and 0.13 or less, and when it is smaller than 0.027, the function as an adhesive layer may be insufficient, so 0.027 or more is desirable.

  A wire electrode 102 having a semi-cured outermost conductive coating layer 103b having a thickness defined when k is 0.027 or more and 0.13 or less in the above formula is formed on the photovoltaic element 101. By thermocompression bonding with pressure, the width of the outermost conductive coating layer 103b in the portion of the cross section of the wire electrode 102 in contact with the photovoltaic element 101 can be made smaller than the largest width of the cross section of the wire electrode 102, A photovoltaic element 604 with reduced shadow loss and an increased active area can be manufactured.

Moreover, all the structures which implement | achieve the same function irrespective of said structure can be included.
(Metal bus bar)
The metal bus bar 603 according to the present invention is a current collector for collecting current flowing through the wire electrode 102 at one end. From such a viewpoint, as a material used for the metal bus bar 603, a material having a low specific resistance and being stably supplied industrially is desirable.

  As such a material, workable and inexpensive copper is preferably used. When copper is used, a thin metal layer may be provided on the surface for the purpose of preventing corrosion, preventing oxidation, and the like. As the surface metal layer, for example, silver, palladium, an alloy of palladium and silver, or a noble metal that is not easily corroded, such as gold, or a metal having good corrosion resistance such as nickel, solder, or tin is preferably used. As a method for forming the surface metal layer, for example, a vapor deposition method, a plating method, or a cladding method, which are relatively easy to produce, are preferably used.

  The thickness of the metal bus bar 603 is preferably 50 μm or more and 200 μm or less. By setting the thickness to 50 μm or more, it is possible to secure a sufficient cross-sectional area that can sufficiently cope with the generated current density of the photovoltaic element 604, and it can be substantially used as a mechanical coupling member.

The metal bus bar 603 may be provided in any number depending on the form of the photovoltaic element 604, and is not particularly limited to one. The metal bus bar 603 used here preferably has a length substantially the same as the size of the photovoltaic element 101 to be provided. There is no restriction | limiting in particular also about a shape, A foil shape, a column shape, etc. can be used.
(Production method)
Next, an example of a method for disposing the wire electrode 102 on the photovoltaic element 101 will be described in detail with reference to FIGS. 6A to 6D are front views when the photovoltaic element 101 is viewed from the light incident side.
(A) The above-described photovoltaic element 101 is prepared in an arbitrary size.
(B) A line (so-called etching line) 602 from which the transparent conductive film located on the outermost surface is removed is formed. This is a process performed when a short-circuit portion existing around the photovoltaic element 101 does not affect the element efficiency, and when there is no short-circuit portion or the degree of short-circuit is negligible Is not necessary.

In addition, an insulating temporary fixing member 601 such as a double-sided tape is disposed at the end of the photovoltaic element 101. The temporary fixing member 601 is a member for temporarily fixing the wire electrode 102 on the photovoltaic body 101 later, and considering the danger of short-circuiting with the back electrode such as the end of the photovoltaic element, It is preferable that it is an insulating member.
(C) Next, the wire electrodes 102 made of a metal wire having a conductive coating layer are placed on the photovoltaic element 101 at an appropriate pitch interval. At this time, the wire electrode 102 is fixed only on the temporary fixing member 601 at the end of the photovoltaic element 101.
(D) The metal bus bar 603 is disposed on the temporary fixing member 601. Thereafter, heat curing is performed at a desired temperature. At this time, the entire surface of the photovoltaic element 101 may be heated, and the conductive coating layer 103 is cured to fix the wire electrode 102 on the transparent conductive layer, and at the same time, the metal bus bar 603 and the wire electrode 102 are bonded and fixed. .

  Moreover, it is desirable to heat the entire surface of the photovoltaic element 101 simultaneously with the heating step. By heating, the adhesive force of the wire electrode 102 on the transparent conductive layer is improved and the reliability is improved. The pressure is determined by the thickness of the conductive coating layer 103 of the wire electrode 102, the width of the conductive coating layer 103 in contact with the photovoltaic element 101 is smaller than the largest width of the wire electrode 102, and the light The pressure must be below a level that does not destroy the electromotive force body 101. Specifically, a pressure of about 1.1 × 10 5 Pa to 6.0 × 10 5 Pa is suitable. Moreover, all the structures which implement | achieve the same function irrespective of said structure can be included.

  Examples according to the claims of the present application will be described below, but the substantial contents of the present invention are not limited to the specific descriptions of the following examples.

  FIG. 6 shows a first embodiment of the present invention.

  First, the wire electrode 102 used in the present embodiment will be described.

  As the wire electrode 102, an electrode in which two conductive coating layers 103 were coated around a metal wire 104 as shown in FIG.

  As the metal wire 104, a silver clad copper wire having a radius of 40 μm (a silver clad with a thickness of 1 μm around a radius of 39 μm) was prepared.

  Next, a urethane-containing resin paste containing carbon (made in-house) was applied as a first covering layer 103a around the metal wire 104 to a thickness of 5 μm ± 1 μm. About the 1st coating layer 103a, the perfect cured film was produced by letting the history of 280 degreeC and 1 minute which are standard hardening conditions pass through IR oven after application | coating.

  Next, the second coating layer 103b was formed using another urethane-containing resin paste containing carbon (made in-house). The second coating layer 103b was applied with a thickness of 5.8 μm ± 1 μm and dried under the conditions of 120 ° C. and 1 minute. This condition is equal to or lower than the dissociation temperature of the curing agent present in the paste, and the second coating layer 103b is in a state where the solvent is simply volatilized and tack is eliminated.

  In this way, the outermost second covering layer 103b has a thickness of φ102 μm, which is 0.027 or more and 0.13 times or less of the sum of the thickness of the first covering layer 103a and the radius of the metal wire 104 102 was produced.

  Next, in this example, a photovoltaic element (amorphous silicon type) 101 having a pin-type triple structure was manufactured with the layer structure shown in FIG.

  First, a sufficiently degreased and cleaned SUS430BA substrate was put in a DC sputtering apparatus (not shown) and deposited at 450 nm, and then ZnO was deposited at 1000 nm to form a lower electrode 502. The substrate 501 was taken out and placed in a microwave plasma CVD film forming apparatus (not shown), and a bottom layer was formed in this order: a silicon layer as the n layer 503, a silicon germanium layer as the i layer 504, and a silicon layer as the p layer 505. Next, a middle layer and a top layer were formed in the same manner, and a semiconductor layer was deposited. Next, the film was put in a sputtering apparatus (not shown), and ITO was deposited to a thickness of 70 nm as an upper electrode 506 made of a transparent conductive film having a function also serving as an antireflection effect.

  As described above, the photovoltaic element 101 in which the lower electrode 502, the photovoltaic layers (semiconductor layers) 503, 504, and 505 and the upper electrode 506 were deposited on the substrate 501 was produced.

  Thereafter, an unnecessary portion of the upper electrode 506 was removed using an etching paste mainly composed of ferric chloride and a commercially available printing machine so that the size was 30 cm × 30 cm and the effective area of the photovoltaic element 101 was 900 cm 2. . Next, an insulating temporary fixing member 601 was provided outside the effective area of the photovoltaic element 101 and at a position of the first end 706 and the second end 707 facing each other. The temporary fixing member 601 was formed by attaching a polyimide base double-sided adhesive tape having a thickness of 100 μm.

  Next, the operation in which the wire electrode 102 is disposed on the photovoltaic element 711 provided with a temporary fixing member using a wiring machine will be described with reference to FIGS. To do.

  First, as a preparation step for starting the wiring operation, as shown in FIG. 7A, the wire electrode 102 is unwound from the bobbin 701 and is gripped by the gripper 704 at an interval of 5 mm. Pooled in the portion 703. Further, the slack removal mechanism 702 removes slack. Note that the tip of the wire electrode 102 is held by the gripper 704 in a state of protruding about 10 mm from the gripper 704.

  Thereafter, as shown in FIG. 7B, the above-described photovoltaic body 711 is supplied onto the work bed 705, and the photovoltaic body 711 is adsorbed onto the work bed 705 by the suction mechanism B1.

  Next, as shown in FIG. 7C, the gripper 704 is advanced, and the tip of the wire electrode 102 is conveyed to the front end of the photovoltaic element 711. At this time, since the slack eliminating mechanism 702 is in a closed state, the wire electrode 102 is clamped in this portion, and the pool amount of the wire electrode 102 in the step roller mechanism 703 as the gripper 704 moves forward. Gradually decreases. When the pool amount decreases, the wire electrode 102 is weighted by the difference between the weight and the weight of the balance weight, and given a constant tension. As a result, the wire electrode 102 is stretched over the photovoltaic body 711 without any slack.

  When the tip of the wire electrode 102 is conveyed to the front end portion of the photovoltaic element 711 by the gripper 704, the air cylinder is operated and, as shown in FIG. The tip of the wire electrode 102 is pressed onto the photovoltaic body 711 with a force of 100 g (temporary fixing). Then, as shown in FIG. 7 (e), the gripper 704 is opened by operating the air cylinder with the front end of the wire electrode 102 pressed against the photovoltaic element 711 by pressing the front end, and then retracted to the original position. Let

  Next, the metal bus bar 603 is disposed on the temporary fixing member 601, and the heater plate 710 and the cutter 709 are integrally lowered as shown in FIG. As a result, the wire electrode 102 and the metal bus bar 601 are pressed against the photovoltaic element 711 by the heater plate 710.

  When the lowering of the heater plate 710 and the cutter 709 is completed, the heater plate 710 heats the wire electrode 102 at 250 ° C. for 45 seconds, and thermocompression-bonds the wire electrode 102 onto the photovoltaic element 711 and the metal bus bar 603.

  During this thermocompression bonding operation, the wire electrode 102 is clamped by closing the gripper in preparation for cutting the wire electrode 102. Further, the cutter is shifted to a position where it is substantially in contact with the metal bus bar 603 to perform cutting.

  As shown in FIG. 6G, when the thermocompression bonding and cutting of the wire electrode 102 are completed, the heater plate 710 and the cutter 709 are raised.

  The photovoltaic element 604 was obtained through the above steps.

In the cross section of the wire electrode 102 of the photovoltaic element 604 produced in this example, the width of the portion of the outermost conductive coating layer 103 b that is in contact with the photovoltaic element 101 is the widest width of the cross section of the wire electrode 102. Could be smaller than the larger part.
(Comparative Example 1)
As the metal wire 104, a silver clad copper wire having a radius of 50 μm (a silver clad with a thickness of 1 μm around a radius of 49 μm) was prepared.

  Next, a urethane-containing resin paste containing carbon (made in-house) was applied as a first covering layer 103a around the metal wire 104 to a thickness of 5 μm ± 1 μm. About the 1st coating layer 103a, the perfect cured film was produced by letting the history of 280 degreeC and 1 minute which are standard hardening conditions pass through IR oven after application | coating.

  Next, the second coating layer 103b was formed using another urethane-containing resin paste containing carbon (made in-house). The second coating layer 103b was applied with a thickness of 20 μm ± 1 μm and dried under the conditions of 120 ° C. and 1 minute. This condition is equal to or lower than the dissociation temperature of the curing agent present in the paste, and the second coating layer 103b is in a state where the solvent is simply volatilized and tack is eliminated. In this way, the outermost second covering layer 103b has a φ150 μm wire electrode 102 of 0.36 times larger than the sum of the thickness of the first covering layer 103a and the radius of the metal wire 104, 0.36 times. Produced.

  Processes, configurations, materials, functions, and actions other than those described above are the same as those in the first embodiment, and thus are omitted.

In the cross section of the wire electrode 102 of the photovoltaic element 604 produced in this comparative example, the width of the portion of the outermost conductive coating layer 103b that is in contact with the photovoltaic element 101 is the widest cross section of the wire electrode 102. Larger than the larger part.
(Comparative Example 2)
As the metal wire 104, a silver clad copper wire having a radius of 40 μm (a silver clad with a thickness of 1 μm around a radius of 39 μm) was prepared.

  Next, a urethane-containing resin paste containing carbon (made in-house) was applied as a first covering layer 103a around the metal wire 104 to a thickness of 5 μm ± 1 μm. About the 1st coating layer 103a, the perfect cured film was produced by letting the history of 280 degreeC and 1 minute which are standard hardening conditions pass through IR oven after application | coating.

  Next, the second coating layer 103b was formed using another urethane-containing resin paste containing carbon (made in-house). The second coating layer 103b was applied at a thickness of 1.2 μm ± 1 μm and dried under the conditions of 120 ° C. and 1 minute. This condition is equal to or lower than the dissociation temperature of the curing agent present in the paste, and the second coating layer 103b is in a state where the solvent is simply volatilized and tack is eliminated. In this way, the thickness of the outermost second coating layer 103b is 0.026 times smaller than the sum of the thickness of the first coating layer 103a and the radius of the metal wire 104, which is 0.026 times φ92.4 μm wire electrode. 102 was produced.

  Processes, configurations, materials, functions, and actions other than those described above are the same as those in the first embodiment, and thus are omitted.

  In the cross section of the wire electrode 102 of the photovoltaic element 604 produced in this comparative example, the width of the portion of the outermost conductive coating layer 103b that is in contact with the photovoltaic element 101 is the widest cross section of the wire electrode 102. However, the wire electrode 102 thermocompression-bonded on the photovoltaic element 101 is easily peeled off, causing a problem in reliability.

  The present invention can be applied to a photovoltaic device and a manufacturing method thereof to increase the active area, reduce power generation loss due to shadow loss, and obtain high conversion efficiency.

It is sectional drawing of the photovoltaic element which concerns on this invention. It is a figure explaining a wire electrode. It is sectional drawing of the wire electrode thermocompression-bonded on the photovoltaic element which concerns on this invention. It is a figure explaining the wire electrode which concerns on this invention. It is a figure explaining a photovoltaic body. It is a figure explaining the photovoltaic device which concerns on this invention, and its manufacturing method. It is a figure explaining the Example of this invention. It is sectional drawing of the conventional photovoltaic device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Photovoltaic body 102 Wire electrode 103 Conductive coating layer 103a 1st coating layer 103b 2nd coating layer 104 Metal wire 105 Surface protective layer 106 Incident light 501 Substrate 502 Lower electrode 503 n-type semiconductor 504 i-type semiconductor 505 p-type semiconductor 506 Upper electrode 601 Temporary fixing member 602 Etching line 603 Metal bus bar 604 Photovoltaic element 701 Bobbin cassette 702 Loosening mechanism 703 Step roller mechanism 704 Gripper 705 Worm bed 706 First end 707 Second end 708 Holding spring 709 Cutter 710 Heater plate 711 Photovoltaic element

Claims (5)

In the method of manufacturing a photovoltaic element, in which a wire electrode made of a metal wire having an uncured conductive coating layer is disposed on a photovoltaic body through the conductive coating layer,
A step of disposing the wire electrode on the photovoltaic element, wherein the conductive coating layer has a thickness of not more than 0.13 times the radius of the metal wire; and placing the metal bus bar on the wire electrode. A method of manufacturing a photovoltaic device, comprising: a step; and a step of thermocompression bonding the disposed metal wire onto the photovoltaic body.   2. The photovoltaic device according to claim 1, further comprising a step of disposing the wire electrode on the photovoltaic body, wherein the thickness of the conductive coating layer is 0.027 times or more the radius of the metal wire. Device manufacturing method. A wire electrode made of a metal wire having at least two conductive coating layers and having an uncured outermost conductive coating layer is disposed on the photovoltaic element via the conductive coating layer. In the method for manufacturing a photovoltaic device,
The wire electrode in which the thickness of the conductive coating layer of the outermost layer is not more than 0.13 times the sum of the thickness of the conductive coating layer other than the outermost layer and the radius of the metal wire is disposed on the photovoltaic element. A photovoltaic device comprising: a step of placing; a step of placing the metal bus bar on the wire electrode; and a step of thermocompression bonding the disposed metal wire onto the photovoltaic body. Manufacturing method.   The wire electrode in which the thickness of the conductive coating layer of the outermost layer is 0.027 times or more the sum of the thickness of the conductive coating layer other than the outermost layer and the radius of the metal wire is disposed on the photovoltaic element. The method for manufacturing a photovoltaic device according to claim 1, further comprising a step of providing the photovoltaic device. In a photovoltaic device provided with a wire electrode made of a metal wire having a conductive coating layer,
The photovoltaic element, wherein a width of the conductive coating layer in a portion of the cross section of the wire electrode in contact with the photovoltaic element is smaller than a width of the widest section of the cross section of the wire electrode.

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