JP2015195297A - solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell module capable of excellently maintaining conductive connectivity between a wiring electrode and a solar cell while having a low cost structure using an aluminum wiring electrode.SOLUTION: The solar cell module includes: a solar cell (20) provided with a connection electrode (20a) on a rear face (20c), which is on the opposite side of the light-receiving face (20b); a wiring board (50), arranged oppositely to the rear face of the solar cell (20), provided with a wiring circuit (53) for wiring the connection electrode (20a) at a position facing the connection electrode (20a); and a conductive connecting material (40) for electrically connecting the connection electrode (20a) and the wiring circuit (53). The wiring circuit (53) is composed of aluminum or an aluminum alloy. The conductive connecting material (40) is composed of a resin in which conductive carbon particles are dispersed.

Description

  The present invention relates to a solar cell module.

Conventionally, the electricity generated by the solar cells is collected through an interconnector stretched around the light-receiving side surface. However, since the interconnector covers a part of the light receiving surface of the solar battery cell, there is a problem in that the power generation efficiency of the solar battery cell is reduced.
In order to solve this problem, for example, Patent Document 1 proposes a back contact type solar cell module in which both the n-type electrode and the p-type electrode of a solar cell are installed on the back surface opposite to the light receiving surface. ing. This back contact type solar cell module can be connected on the back surface opposite to the light receiving surface, and can prevent a decrease in power generation efficiency without covering the light receiving surface.

In such a back contact solar cell module, a wiring board is disposed opposite to the back surface opposite to the light receiving surface of the solar battery cell, and a laminate in which a metal foil for forming a wiring pattern is attached to the wiring board is provided as an interface. It is provided as an alternative wiring circuit (wiring electrode) for the connector. In general, copper is used as the metal forming the wiring circuit from the viewpoint of conductivity.
However, since copper is expensive, it has been proposed to use aluminum which is cheaper than copper for wiring (Patent Documents 2 and 3).

JP 2005-011869 A International Publication No. 2013/146414 JP2013-207219A

However, the prior art as described above has the following problems.
In a circuit using copper, solder or silver paste is generally used as a conductive bonding material for electrically connecting the circuit, an n-type electrode, and a p-type electrode (connection electrode). Since the output of the solar cell is reduced by the connection resistance between the conductive bonding material and the wiring circuit, it is necessary to make the connection resistance as small as possible. However, since the circuit using aluminum is an oxide film on the aluminum surface, the connection resistance with the solder is very large, and it is not practical to use the solder for the conductive bonding material. Also, when a silver paste is used for the conductive bonding material, the connection resistance becomes very large as compared with a wiring circuit using copper. This is particularly noticeable when used in a wet and hot environment. Even if the connection resistance is low at the beginning of the connection, the connection resistance rapidly increases with time, and long-term reliability in a humid and hot environment is required. It cannot be used for batteries.

Also, in order to solve such problems, the conductive connectivity can be improved by plating the surface of a wiring circuit (wiring electrode) using aluminum with copper or nickel. The advantage of using aluminum as a circuit material is diminished.
The present invention has been made in view of the above-described problems, and it has a low-cost configuration using aluminum wiring electrodes, but has good conductive connectivity between the wiring circuit and the solar cells. An object is to provide a solar cell module that can be maintained.

One embodiment of the present invention is a solar cell in which a connection electrode is provided on the back surface opposite to the light receiving surface, and is disposed to face the back surface of the solar cell, and for wiring the connection electrode at a position facing the connection electrode. A wiring board provided with a wiring electrode; and a conductive bonding material for electrically connecting the connection electrode and the wiring electrode. The wiring electrode is made of aluminum or an aluminum alloy, and the conductive bonding material is conductive It is characterized by being made of a resin in which conductive carbon particles are dispersed.
Another aspect of the present invention is characterized in that the height of the conductive bonding material is higher than the thickness of the sealing material interposed between the solar battery cell and the wiring board.
Furthermore, in another aspect of the present invention, the conductive bonding material further includes at least one of particles made of silver, copper, tin, and lead.

In another aspect of the present invention, the conductive bonding material includes a layer made of at least one of a cured product of silver paste, a cured product of copper paste, and solder, and a layer made of a cured product of conductive carbon paste. It is a laminate, and a layer made of a cured product of conductive carbon paste is in contact with the wiring electrode.
Furthermore, another aspect of the present invention includes a sealing material interposed between the solar battery cell and the wiring substrate, and the sealing material is made of a polyolefin-based resin.
Another aspect of the present invention is characterized in that the polyolefin-based resin is linear low-density polyethylene.
Furthermore, another aspect of the present invention is characterized in that the wiring board includes a base material that supports the wiring electrode, and the water vapor transmission rate of the base material is 1.0 g / m ² / day or less.

  According to one embodiment of the present invention, even when aluminum or an aluminum alloy is used for the wiring electrode, the conductive connectivity between the connection electrode and the wiring electrode can be favorably maintained. Therefore, the conductive connectivity between the wiring electrode and the solar cell can be favorably maintained while having a low-cost configuration using the wiring electrode made of aluminum.

It is typical sectional drawing which shows an example of a structure of the solar cell module of embodiment of this invention. It is a typical top view which shows an example of the electrode part of the solar cell module of embodiment of this invention. It is typical sectional drawing which shows another example of a structure of the solar cell module of embodiment of this invention. It is typical sectional drawing which shows another example of a structure of the solar cell module of embodiment of this invention. It is typical sectional drawing which shows another example of the structure of the solar cell module which is a modification of embodiment of this invention. It is typical sectional drawing which shows another example of the structure of the solar cell module which is a modification of embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, even if the embodiments are different, the same or corresponding members are denoted by the same reference numerals, and common description is omitted.
(Constitution)
As shown in FIG. 1, a solar cell module 1 includes a solar cell 20 and a wiring substrate 50 disposed opposite to the surface opposite to the light receiving surface 20 b of the solar cell 20 (hereinafter also referred to as “back surface 20 c”). And a sealing material 30 that is laminated on the wiring substrate 50 and the solar battery cell 20 to seal the solar battery cell 20, and a conductive bonding material 40 that electrically connects the wiring board 50 and the solar battery cell 20. And a translucent substrate 60 laminated on the sealing material 30. Thereby, the solar cell module 1 forms a back contact type solar cell module.

The photovoltaic cell 20 generates electricity by photoelectrically converting light incident from the light receiving surface 20b. As the solar battery cell 20, an appropriate solar battery cell can be adopted as long as it is a so-called back contact solar battery cell in which the connection electrode 20 a is provided on the back surface 20 c opposite to the light receiving surface 20 b. . Although the illustration is simplified in FIG. 1 for a schematic diagram, the number of connection electrodes 20a can be appropriately set to two or more as necessary.
The connection electrode 20a is formed in a circular shape with a diameter w _20a , for example. Moreover, as a material of the connection electrode 20a, what baked silver paste is employable, for example. Each connection electrode 20a may have a different size and shape, but in the following description, each connection electrode 20a will be described as having the same size and shape as an example.
Moreover, as shown in a two-dot chain line in FIG. 2, for example, an appropriate plan view shape such as a rectangular shape can be adopted as the plan view shape of the solar battery cell 20.

In FIG. 1 and FIG. 2, the illustration is simplified for the sake of schematic illustration, but the solar cell module 1 includes a plurality of solar cells 20. That is, the plurality of solar battery cells 20 are arranged in the wiring board 50 with a gap. Although illustration is abbreviate | omitted in this embodiment, the several photovoltaic cell 20 is arranged in the illustration left-right direction and illustration depth direction of FIG. As a result, they are arranged in a rectangular lattice shape in plan view.
As shown in FIG. 1, the wiring board 50 is formed by laminating a weather resistant resin layer 54, a base material 51 (base material), an insulating adhesive layer 52, and a wiring circuit 53 (wiring electrode) in this order. is there.
The wiring circuit 53 forms a wiring pattern for wiring the connection electrode 20a. As the planar view shape of the wiring circuit 53, an appropriate planar view shape designed according to the arrangement of the connection electrodes 20a of the solar battery cells 20 can be adopted. The wiring circuit 53 is laminated on the base material 51 via the insulating adhesive layer 52 and is bonded to the base material 51 integrally.

As the wiring pattern, for example, as shown in FIG. 2, a comb tooth portion 53A in which four linear portions 53a1, 53a2, 53a3, 53a4 having a substantially constant line width are arranged in a comb shape, Four linear portions 53b1, 53b2, 53b3, 53b4 having a substantially constant line width have comb teeth 53B arranged in a comb shape, and these comb teeth 53A, 53B are mutually There is a pattern that penetrates into the gaps between the linear portions and is closely spaced from each other.
In this pattern, the comb-like portions 53A and 53B correspond to the positive electrode wiring and the negative electrode wiring of the power generation output of the solar battery cell 20, respectively. Further, above the comb-like portions 53A and 53B (on the translucent substrate 60 side), as shown by a two-dot chain line in FIG. 2, the solar battery cell 20 is positioned so as to cover the comb-like portions 53A and 53B from above. Is placed. The solar battery cell 20 is provided with a total of 24 connection electrodes 20a (refer to the two-dot chain line in FIG. 2), three at each position facing the linear portions 53a1 to 53a4 and 53b1 to 53b4. Yes. Further, three conductive bonding materials 40 to be described later are bonded to the respective linear portions 53a1 to 53a4 and 53b1 to 53b4 of each pattern of the wiring circuit 53 at positions facing the connection electrodes 20a.

In addition, the shape of the pattern of the wiring circuit 53 shown in FIG. 2 and the number and arrangement of the connection electrodes 20a of the solar battery cells 20 are merely examples, and are not limited thereto.
In addition, as a material of the wiring circuit 53, for example, an appropriate material can be employed depending on the purpose, of aluminum or an aluminum alloy. In order to ensure good electrical conductivity and corrosion resistance, it is desirable to use high-purity aluminum such as 1000 series, for example. In order to ensure good strength and workability, it is desirable to use a high-strength aluminum alloy such as 3000 series or 8000 series.

The wiring circuit 53 is preferably thicker in order to ensure good electrical conductivity, but it is preferably thinner from the viewpoint of material cost. Specifically, a range of 30 μm to 200 μm is preferable, and a range of 50 μm to 100 μm is particularly preferable.
Further, the surface of the wiring circuit 53 may be subjected to a roughening process. Examples of the roughening method include an etching process, a wet blast process, a sand blast process, and a composite process thereof. When the surface of the wiring circuit 53 is roughened, the contact area with the conductive bonding material 40 increases, and the contact resistance can be reduced. Further, due to the anchor effect, the adhesion with the sealing material 30 can be improved, and the durability of the solar cell module 1 can be improved.

As a method of forming the wiring substrate 50, that is, a method of laminating the weather resistant resin layer 54, the base material 51, the insulating adhesive layer 52, and the wiring circuit 53, for example, there is a dry laminating method or the like. An appropriate adhesive is disposed between the weather resistant resin layer 54 and the substrate 51.
The conductive bonding material 40 electrically connects the connection electrode 20 a and the wiring circuit 53. As a material of the conductive bonding material 40, for example, a resin in which conductive carbon particles are dispersed can be employed. Examples of the resin in which conductive carbon particles are dispersed include a cured product of conductive carbon paste in which conductive carbon particles (carbon powder) are dispersed in a thermosetting binder resin. As a method for forming a cured product of the conductive carbon paste, for example, there is a method in which after the carbon paste is formed into a target shape, the carbon paste is heated to cure the binder resin. The conductive bonding material 40 is in contact with both the connection electrode 20 a and the wiring circuit 53.

The carbon powder is preferably carbon black or graphite from the viewpoint of material cost. In order to ensure good electrical characteristics, carbon nanotubes may be used. The binder resin is preferably a thermosetting resin, and can be selected from appropriate ones such as epoxy, polyester, and acrylate.
The conductive carbon paste (conductive bonding material 40) may further include at least one of particles made of silver, copper, tin, and lead in addition to the carbon powder. Thereby, the specific resistance of the conductive bonding material 40 can be reduced.

  As such a conductive carbon paste, a commercially available one may be used as appropriate. However, in order to improve the electrical connection between the connection electrode 20a and the wiring circuit 53, it is desirable that the specific resistance is low. The resistance value of the conductive bonding material 40, which is a cured product of the conductive carbon paste, is preferably 100 mΩ or less between the connection electrode 20a and the wiring circuit 53, and more preferably 10 mΩ or less. In order to obtain such a resistance value, the shape of the conductive bonding material 40 and the specific resistance of the conductive carbon paste are adjusted. When considering a shape equivalent to the shape of the conductive bonding material 40 of the conventional solar cell module 1, the specific resistance of the conductive carbon paste is preferably 1 Ω · cm or less, and more preferably 0.1 Ω · cm or less. it is conceivable that.

Further, it is desirable that the connection resistance between the connection electrode 20a and the conductive bonding material 40 and the connection resistance between the wiring circuit 53 and the conductive bonding material 40 are low. Although it depends on the resistance of the conductive bonding material 40, the connection resistance is preferably 100 mΩ or less, and more preferably 10 mΩ or less.
The conductive bonding material 40 and the wiring circuit 53 are considered to be electrically connected as follows because an insulating oxide film exists on the aluminum surface. That is, due to the pressurization in the laminating process described later, aluminum (wiring circuit 53) is slightly deformed and a defect is generated in the oxide film, and the aluminum (wiring circuit 53) and the conductive bonding material 40 are pressurized through the generated defect. The conductive bonding material 40 and the wiring circuit 53 are electrically bonded to each other in a state in which is added. In addition, the conductive carbon particles (carbon powder) of the conductive bonding material 40 break through the oxide film on the aluminum surface, and the aluminum (wiring circuit 53) under the oxide film and the conductive bonding material 40 are under pressure. The conductive bonding material 40 and the wiring circuit 53 are electrically bonded to each other.

  Moreover, in the electrical joining in the state where the pressure as described above is applied, the pressure between the conductive joining material 40 and the wiring circuit 53 that existed at the beginning of the joining decreases with time due to the stress relaxation of aluminum. . At this time, if the potential difference between the conductive bonding material 40 and aluminum (wiring circuit 53) is large, electrolytic corrosion proceeds and the connection resistance increases. This progresses violently when water enters the vicinity of the contact point between the conductive bonding material 40 and aluminum (wiring circuit 53) in a moist heat environment, and further increases when oxygen or carbon dioxide dissolves in the water. When a conventionally hardened material of silver paste is used as the conductive bonding material 40, the potential difference between silver and aluminum is large, so that it is considered that electrolytic corrosion progresses and connection resistance increases when used for a long time in a humid heat environment. . On the other hand, the conductive carbon particles (carbon powder) used as the conductive bonding material 40 in this embodiment have a small potential difference with aluminum, so that the progress of electrolytic corrosion is small. The rise can be kept small.

  The weather resistant resin layer 54 forms an outer surface in the stacking direction of the wiring substrate 50 and protects the base material 51, the insulating adhesive layer 52, and the wiring circuit 53. As a material of the weather resistant resin layer 54, for example, an appropriate resin material excellent in moisture and heat resistance and ultraviolet blocking property can be adopted. Examples of the resin material include fluorine-based resins such as polyvinyl fluoride, polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, and polytetrafluoroethylene. These resins may be used alone, or may be used by adding fillers such as titanium oxide and silica. The weather resistant resin layer 54 may be provided by laminating a film of weather resistant resin on the substrate 51, or may be provided directly on the substrate 51 by coating.

The substrate 51 is laminated on the weather resistant resin layer 54 and supports the wiring circuit 53 via the insulating adhesive layer 52. The substrate 51 is preferably a flexible sheet-like member. Moreover, it is preferable that the base material 51 consists of a material excellent in electrical insulation. As the base material 51, a resin material formed in a sheet shape or a film shape can be employed.
As a material of the base material 51, for example, a resin material such as acrylic, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, polyimide, urethane, epoxy, melamine, styrene, or a resin material obtained by copolymerizing them can be used. Among these, polyethylene terephthalate and polyethylene naphthalate are preferable from the viewpoint of a balance between performance and cost. In addition, in order to control heat insulation, elasticity, and optical characteristics, a material mixed with an organic filler, an inorganic filler, an ultraviolet absorber, an antioxidant, or the like can be used as necessary.

Moreover, as the base material 51, not only what consists of a single resin material, For example, the laminated film which laminated | stacked two or more of said resin materials, the layer which consists of said resin material, and the barrier film mentioned later A composite laminated film in which a functional layer is laminated can also be adopted.
When the base material 51 has the strength and weather resistance required for the outer surface of the solar cell module 1, the weather resistant resin layer 54 may be deleted, and the base material 51 may also serve as the weather resistant resin layer 54.
In addition, the base material 51 desirably has a function (hereinafter also referred to as “barrier property”) that prevents water, oxygen, carbon dioxide, and the like from entering the solar cell module 1 from the outside environment. In order for the base material 51 to have barrier properties, it is desirable to use, for example, a barrier film or a composite laminated film of a resin film and a barrier film. As the material of the barrier film, for example, an appropriate resin material having an excellent barrier property against moisture and oxygen, an aluminum foil, a composite laminated film of an aluminum foil and an appropriate resin, and alumina, silica, or the like is vapor-deposited on the resin film. Film can be employed.

If the base material 51 has a barrier property, it is possible to suppress intrusion of water, oxygen, carbon dioxide, or the like into the solar cell module 1 even in a humid heat environment. Therefore, electrolytic corrosion near the contact point between the conductive bonding material 40 and aluminum (wiring circuit 53) can be suppressed, and an increase in connection resistance can be suppressed. As the barrier property of the barrier film, the water vapor transmission rate is preferably 1.0 g / m ² / day or less from the viewpoint of maintaining the electrical connection between the conductive bonding material 40 and the wiring circuit 53.
The insulating adhesive layer 52 fixes the wiring circuit 53 on the surface of the substrate 51. As a material of the insulating adhesive layer 52, for example, urethane, acrylic, epoxy, polyimide, olefin, which is a curable resin, or a curable adhesive obtained by copolymerizing these can be used. The kind of curable adhesive is not specifically limited, For example, a thermosetting adhesive, a UV curable adhesive, etc. can be employ | adopted suitably. Moreover, you may use the adhesive agent which is not a step hardening type.

The sealing material 30 is laminated on the wiring substrate 50 and the solar battery cell 20 to seal and insulate the solar battery cell 20. As the sealing material 30, a thermoplastic resin film can be employed.
As the material of the sealing material 30, for example, a film material made of polyolefin resin, ethylene / vinyl acetate copolymer (EVA), ethylene / methacrylic acid copolymer (EMAA), or the like can be employed. Among these, polyolefin resin is particularly preferable. Examples of polyolefin resins include α-olefins such as ethylene, propylene, 1-butene, isobutylene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene, vinyl acetate, and (meth) acrylic acid. One or two or more types of unsaturated monomers such as methyl, ethyl (meth) acrylate, isopropyl (meth) acrylate, and maleic anhydride can be used. From the viewpoints of mechanical properties such as flexibility and processing suitability such as melting point and melt flow rate, an ethylene / α-olefin copolymer is preferable, and linear low density polyethylene (LLDPE) is particularly preferable.

  It is desirable for the sealing material 30 to generate less carboxylic acid due to hydrolysis in a humid heat environment. In this embodiment, since aluminum is used for the wiring circuit 53, the use of a material that generates a large amount of carboxylic acid may increase the electrolytic corrosion of the connection electrode 20a. Polyolefin resins such as LLDPE are considered to be particularly suitable because they generate little carboxylic acid due to hydrolysis even in a humid heat environment. Moreover, it is desirable that both of the transparent sealing material sheets 31 and 32 of the sealing material 30 are polyolefin resins. However, the polyolefin resin is used only for the sealing material sheet 32 that is in direct contact with the connection electrode 20a. For the stopping material sheet 31, for example, a configuration using a resin that easily generates carboxylic acid such as EVA can be used.

Further, the sealing material 30 may contain various additives such as an ultraviolet absorber, an antioxidant, a light stabilizer, and a carbon dioxide scavenger. In particular, when a carbon dioxide scavenger is included, the carbon dioxide concentration in the solar cell module 1 can be reduced. Therefore, it is desirable from the viewpoint of preventing electrolytic corrosion near the contact point between the conductive bonding material 40 and aluminum (wiring circuit 53).
As shown in FIG. 1, the sealing material 30 is laminated by sandwiching the solar battery cell 20 between the sealing material sheet 32 composed of the thermoplastic resin film as described above and the transparent sealing material sheet 31. It is formed by.

The sealing material sheet 32 is inserted between the solar battery cell 20 and the wiring board 50, and seals the solar battery cell 20 from the back surface 20c side. Since the sealing material sheet 32 forms a region of the sealing material 30 closer to the wiring substrate 50 than the light receiving surface 20 b of the solar battery cell 20, it does not require light transmittance. For this reason, as a material of the sealing material sheet | seat 32, the various film which has light absorptivity, light-scattering property, and light reflectivity is employable, for example. For example, a colored film containing a color material having an appropriate color, such as a black film or a white film, can be suitably used.
When a colored film such as a black film or a white film is used as the sealing material sheet 32, the surface of the wiring substrate 50 cannot be visually recognized from the light-transmitting substrate 60 side through the gap between the solar cells 20. Therefore, the designability of the solar cell module 1 can be improved.

The transparent sealing material sheet 31 seals the solar battery cell 20 from the light receiving surface 20b side. Since the transparent sealing material sheet 31 forms the region of the sealing material 30 closer to the light transmissive substrate 60 than the light receiving surface 20b of the solar battery cell 20, it requires light transmission. For this reason, as a material of the transparent sealing material sheet 31, for example, various transparent films having optical transparency can be adopted.
The translucent substrate 60 is a member that guides incident light to the light receiving surface 20 b of the solar battery cell 20 and constitutes an outer surface opposite to the weather resistant resin layer 54. As a material of the translucent substrate 60, for example, a tempered glass plate is desirable from the viewpoints of light transmittance, weather resistance, and strength. Further, for example, a plastic plate or sheet such as a fluorine resin or an acrylic resin can be used.

(Production method)
Next, the manufacturing method of the solar cell module 1 is demonstrated.
A conductive carbon paste is applied onto the wiring substrate 50 in the shape of the conductive bonding material 40 (wiring pattern). As a method for applying the conductive carbon paste, for example, a printing method capable of forming an arbitrary pattern such as screen printing or stencil printing can be employed.
Subsequently, when the application of the conductive carbon paste is completed, the wiring substrate 50, the sealing material sheet 32, the solar battery cell 20, the transparent sealing material sheet 31, and the translucent substrate 60 to which the conductive carbon paste is applied are formed. , And arrange them in this order. At that time, the conductive bonding material 40 can penetrate at least at a position where the conductive bonding material 40 is located in the sealing material sheet 32 so that the connection electrode 20a and the conductive carbon paste (conductive bonding material 40) are in contact with each other. Make a hole of size.

Subsequently, using a laminator, the laminated body of the wiring substrate 50, the sealing material sheet 32, the solar battery cell 20, the transparent sealing material sheet 31, and the translucent substrate 60 is heated in the stacking direction under vacuum. Vacuum pressurization laminating (hereinafter also referred to as “lamination process”) is performed. The processing conditions of the heating temperature and the applied pressure are temperatures at which the encapsulant sheet 32 and the transparent encapsulant sheet 31 are softened and deformed, and are in close contact with the surfaces of adjacent members, and conductive bonding. The heating temperature and the applied pressure are such that the material 40 is cured and the connection electrode 20a and the wiring circuit 53 are electrically joined.
By the heating in the laminating process, the sealing material sheet 32 and the transparent sealing material sheet 31 are softened, deformed, and integrated. In addition, the softened sealing material sheet 32 and the transparent sealing material sheet 31 flow and are in close contact with the surfaces of adjacent members. Thereby, the outer peripheral part of the photovoltaic cell 20 is sealed, and the layer of the sealing material 30 is formed between the wiring substrate 50 and the translucent substrate 60.

In addition, due to the pressurization in the laminating process, the wiring circuit 53 is slightly deformed to cause a defect in the oxide film on the surface of the wiring circuit 53 (aluminum), and the aluminum under the oxide film and the conductive bonding material 40 are in contact with each other. To do. Thereby, the conductive bonding material 40 and the wiring circuit 53 are electrically bonded. Furthermore, the conductive carbon particles (carbon powder) of the conductive bonding material 40 break through the oxide film on the surface of the wiring circuit 53 (aluminum), and the aluminum under the oxide film and the conductive bonding material 40 come into contact with each other. Thereby, the conductive bonding material 40 and the wiring circuit 53 are electrically bonded.
And when a lamination process is complete | finished, it solidifies in the state to which each layer and each member 20, 30, 40, 50, 60 were adhere | attached. Thereby, the solar cell module 1 is formed.
Such a laminating process is usually performed at a temperature of 130 ° C. to 200 ° C. for 5 to 30 minutes. Then, while the vacuum pressure lamination is performed, the softening deformation of the sealing material sheet 32 and the curing of the conductive bonding material 40 are performed simultaneously. Therefore, depending on the curing conditions of the conductive bonding material 40, the conductive bonding material 40 may be deformed or disconnected due to softening deformation of the sealing material sheet 32 before the conductive bonding material 40 is sufficiently cured. Therefore, it is necessary to design the curing conditions of the conductive bonding material 40 so as not to be affected by the softening deformation of the sealing material sheet 32.

Further, the height of the conductive bonding material 40 may be higher than the thickness of the sealing material sheet 32 as shown in FIG. As a result, the deformation of aluminum at the time of pressurization in the laminating process can be increased, the defects of the surface oxide film can be increased, or the conductive carbon particles of the conductive bonding material 40 can easily break through the oxide film. be able to. In order to obtain such a shape, the height of the print pattern (conductive carbon paste) may be made higher than the thickness of the encapsulant sheet 32 when the conductive bonding material 40 is provided by printing. Moreover, even if the height of a printing pattern is below the thickness of the sealing material sheet 32, as shown in FIG. 4 by enlarging the hole made in the location where the electrically conductive joining material 40 is located of the sealing material sheet 32. Furthermore, the thickness of the sealing material sheet 32 around the conductive bonding material 40 can be reduced, and the height of the conductive bonding material 40 can be relatively increased.
The use of a cured conductive carbon paste as the conductive bonding material 40 has the following advantages. Although the hardened | cured material of silver paste is used in the conventional structure as the electrically conductive joining material 40, it can be set as a further low-cost solar cell module by substituting it with the hardened | cured material of cheap conductive carbon paste. .

(Effect of this embodiment)
This embodiment has the following effects.
(1) The solar cell module 1 according to the present embodiment is disposed so as to be opposed to the solar cell 20 in which the connection electrode 20a is provided on the back surface 20c opposite to the light receiving surface 20b, and the back surface 20c of the solar cell 20. Conductive circuit for electrically connecting the wiring substrate 50 provided with the wiring circuit 53 (wiring electrode) for wiring the connecting electrode 20a at a position facing the electrode 20a, and the connecting electrode 20a and the wiring circuit 53 (wiring electrode). And a bonding material 40. In the solar cell module 1 according to this embodiment, the wiring circuit 53 (wiring electrode) is made of aluminum or an aluminum alloy, and the conductive bonding material 40 is made of a resin in which conductive carbon particles are dispersed.
According to such a configuration, even when aluminum or an aluminum alloy is used for the wiring circuit 53, the conductive connectivity between the connection electrode 20a and the wiring circuit 53 can be favorably maintained. Therefore, the conductive connectivity between the wiring circuit 53 and the solar battery cell 20 can be satisfactorily maintained while having a low cost configuration using the wiring circuit 53 made of aluminum.

(2) In the solar cell module 1 according to the present embodiment, the height of the conductive bonding material 40 is higher than the thickness of the sealing material sheet 32 interposed between the solar cells 20 and the wiring substrate 50.
According to such a configuration, the deformation of aluminum during pressurization in the laminating process can be increased, defects in the surface oxide film can be increased, or the conductive carbon particles of the conductive bonding material 40 are oxidized. It is possible to easily break through the film.
(3) In the solar cell module 1 according to this embodiment, the conductive bonding material 40 further includes at least one of particles made of silver, copper, tin, and lead.
According to such a configuration, the specific resistance of the conductive bonding material 40 can be reduced.

(4) The solar cell module 1 according to this embodiment includes a sealing material sheet 32 that is interposed between the solar cells 20 and the wiring substrate 50 and made of a polyolefin-based resin.
According to such a structure, generation | occurrence | production of the carboxylic acid by the hydrolysis in a humid heat environment can be reduced, and even if it uses aluminum for the wiring circuit 53, the electrolytic corrosion of the connection electrode 20a can be suppressed.
(5) In the solar cell module 1 according to this embodiment, the polyolefin-based resin is linear low-density polyethylene.
According to such a configuration, mechanical properties such as flexibility, processing suitability such as melting point, and the like can be improved.
(6) In the solar cell module 1 according to the present embodiment, the water vapor permeability of the base material 51 is 1.0 g / m ² / day or less.
According to such a configuration, entry of water, oxygen, carbon dioxide and the like can be suppressed even in a humid heat environment, and the electrical connectivity between the conductive bonding material 40 and aluminum can be more appropriately maintained.

(Modification)
One modification of this embodiment is shown in FIG. In this modification, the conductive bonding material 40 is a laminated body of the cell-side bonding material 41 and the back surface-side bonding material 42. The connection electrode 20 a is bonded to the cell side bonding material 41, and the wiring circuit 53 is bonded to the back surface side bonding material 42. The cell-side bonding material 41 is a layer made of at least one of a cured product of silver paste, a cured product of copper paste, and solder. The back-side bonding material 42 is a layer made of a cured product of conductive carbon paste. According to such a configuration, the electrical connection between the connection electrode 20a of the cell and the conductive bonding material 40 can be made as good as that of the conventional back contact solar cell module, and the wiring circuit 53 made of aluminum and the conductive layer can be electrically connected. The electrical connectivity with the bonding material 40 can also be improved.
Although the cell side bonding material 41 and the back surface side bonding material 42 are shown in FIG. 5 to have the same cross-sectional shape, for example, as shown in FIG. 6, the cell side bonding material 41 and the back surface side bonding material 42 have different cross sections. You may have a shape. As shown in FIG. 6, the connection resistance between the back surface side bonding material 42 and the wiring circuit 53 can be reduced by increasing the contact area between the back surface side bonding material 42 and the wiring circuit 53.

  According to the solar cell module of the present invention, even when inexpensive aluminum is used for the wiring circuit, the connection electrode and the wiring circuit can be favorably bonded using the conductive bonding material. Therefore, a cost-effective solar cell module can be provided.

DESCRIPTION OF SYMBOLS 1 Solar cell module 20 Solar cell 20a Connection electrode 20b Light-receiving surface 20c Back surface 30 Sealing material 31 Transparent sealing material sheet 32 Sealing material sheet 40 Conductive bonding material 41 Cell side bonding material 42 Back surface side bonding material 50 Wiring board 51 group Material 52 Insulating adhesive layer 53 Wiring circuit 54 Weather resistant resin layer 60 Translucent substrate

Claims (7)

A solar cell provided with a connection electrode on the back surface opposite to the light receiving surface;
A wiring substrate that is disposed opposite to the back surface of the solar battery cell and provided with wiring electrodes for wiring the connection electrodes at positions facing the connection electrodes;
A conductive bonding material for electrically connecting the connection electrode and the wiring electrode;
The wiring electrode is made of aluminum or an aluminum alloy,
The solar cell module, wherein the conductive bonding material is made of a resin in which conductive carbon particles are dispersed. A sealing material interposed between the solar battery cell and the wiring board;
The solar cell module according to claim 1, wherein a height of the conductive bonding material is higher than a thickness of the sealing material.   The solar cell module according to claim 1 or 2, wherein the conductive bonding material further includes at least one of particles made of silver, copper, tin, and lead.   The conductive bonding material is a laminate of a layer made of at least one of a cured product of silver paste, a cured product of copper paste, and solder, and a layer made of a cured product of conductive carbon paste. 4. The solar cell module according to claim 1, wherein a layer made of the cured product is in contact with the wiring electrode. 5. A sealing material interposed between the solar battery cell and the wiring board;
The solar cell module according to any one of claims 1 to 4, wherein the sealing material is made of a polyolefin-based resin.   The solar cell module according to claim 5, wherein the polyolefin-based resin is a linear low-density polyethylene. The wiring board includes a base material that supports the wiring electrode,
The solar cell module according to any one of claims 1 to 6, wherein the substrate has a water vapor transmission rate of 1.0 g / m ² / day or less.

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