JP2008294366A - Solar cell module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce contact resistance between a wiring material and a solar cell in order to prevent deterioration of output characteristics. <P>SOLUTION: A solar cell 10 that constitutes a solar cell module 1 includes a photoelectric conversion part 20, a thin line electrode 30 on the light-receiving side and a thin line electrode 31 on the backside. The thin line electrode 30 on the light-receiving side formed on the light-receiving side of the photoelectric conversion part 20 that constitutes the solar battery 10 has a first part 30a joined to the wiring material 40 and a second part 30b not joined to the wiring material 40. The height from the surface of the substrate (light-receiving surface) of the first part 30a is greater than the height from the light-receiving surface of the second part 30b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a solar cell module including a plurality of solar cells connected to each other by a wiring material between a light receiving surface side protective material and a back surface side protective material.

  Solar cells are expected as a new energy source because they can directly convert light from the sun, a clean and inexhaustible energy source, into electricity.

  The output per solar cell is about several watts. Therefore, when a solar cell is used as a power source for a house or a building, a solar cell module in which a plurality of solar cells are electrically connected in series or in parallel with a wiring material and sealed with a sealing material is used.

In general, a plurality of thin wire electrodes for collecting carriers and a bus bar electrode for collecting carriers from the thin wire electrodes are integrally formed on the solar cell substrate. The wiring member is joined to the bus bar electrode of one solar cell and the bus bar electrode of another solar cell adjacent to the one solar cell. Specifically, the wiring material is firmly bonded to the bus bar electrode through a solder alloy layer formed at the interface between the solder layer of the wiring material and the bus bar electrode (see, for example, Patent Document 1).
JP 2002-359388 A

  On the other hand, it has been proposed by the present applicant to reduce the manufacturing cost by joining the wiring material to the thin wire electrode via a resin adhesive without forming the bus bar electrode (Japanese Patent Application No. 2006-229209).

  Thus, in the technique of directly joining the wiring material to the fine wire electrode without forming the bus bar electrode, if the bus bar electrode is simply removed, the contact area between the wiring material and the fine wire electrode is reduced. As a result, the electrical contact resistance at the interface between the wiring material and the fine wire electrode is increased, and there is a possibility that the output characteristics as the solar cell module are deteriorated.

  It is also conceivable to reduce the contact resistance between the wiring material and the fine wire electrode by increasing the line width of the fine wire electrode. However, there is a limit to increasing the line width of the thin wire electrode from the viewpoint of securing the light receiving area of the solar cell.

  Accordingly, the present invention provides a solar cell module in which the contact resistance between the wiring material and the fine wire electrode is reduced and the output characteristics are improved in a method of directly joining the wiring material to the fine wire electrode without forming the bus bar electrode. For the purpose.

  In order to achieve the above-described object, one feature of the present invention is that the light receiving surface side protective material, the back surface side protective material, and the light receiving surface side protective material and the back surface side protective material are mutually connected by the wiring material. A solar cell module comprising a plurality of connected solar cells, the solar cell having a substrate and a plurality of thin wire electrodes formed on the surface of the substrate, the wiring material and the solar cell Is bonded via a resin layer, and the wiring member is arranged so as to intersect with the thin wire electrode, and the thin wire electrode includes a first portion bonded to the wiring member, and the wiring member. The second portion is not bonded to the substrate, and the height of the first portion from the surface of the substrate is larger than the height of the second portion from the surface of the substrate.

  According to this feature, the height from the substrate surface of the first portion of the thin wire electrode joined to the wiring material is higher than the height from the substrate surface of the second portion, so the height from the substrate surface is uniform. Compared with the formed thin wire electrode, the contact area between the thin wire electrode and the wiring material is increased. Therefore, the contact resistance can be reduced. Thereby, the output characteristic of a solar cell module can be improved.

  In the above-described feature, it is preferable that the first portion is covered with the wiring material.

  According to the present invention, there is provided a solar cell module in which contact resistance between a wiring material and a fine wire electrode is reduced and output characteristics are improved in a method of directly joining a wiring material to the fine wire electrode without forming a bus bar electrode. be able to.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Therefore, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(Configuration of solar cell module)
A solar cell module shown as an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration of a solar cell module 1 according to the present embodiment. As shown in FIG. 1, the solar cell module 1 according to the embodiment of the present invention includes a plurality of solar cells 10, a wiring material 40, a sealing material 50, a light receiving surface side protective material 60, and a back surface side protective material 70.

  The solar cell 10 includes a photoelectric conversion unit 20, a light receiving surface side thin wire electrode 30, and a back surface side thin wire electrode 31.

  The photoelectric conversion unit 20 sandwiches a substantially intrinsic amorphous silicon layer between a single crystal silicon substrate and an amorphous silicon layer having opposite conductivity types, reduces defects at the interface, and forms a heterojunction. It is a solar cell substrate having a structure with improved interface characteristics, a so-called HIT structure.

  The photoelectric conversion unit 20 includes a semiconductor material such as a crystalline semiconductor material such as single crystal silicon or polycrystalline silicon, a thin film semiconductor material such as an amorphous silicon alloy or CuInSe, or a compound semiconductor material such as GaAs or InP. An organic material such as a dye-sensitized type can be used. Further, a pn junction or a pin junction may be formed using another method such as thermal diffusion.

  FIG. 2 is a plan view of the solar cell 10 according to the present embodiment. As shown in FIG. 2, a light receiving surface side thin wire electrode 30 is formed on the light receiving surface side surface (hereinafter referred to as a light receiving surface) of the photoelectric conversion unit 20. A large number of light receiving surface side thin wire electrodes 30 are formed substantially in parallel over substantially the entire area of the light receiving surface.

  As shown in FIG. 1, a back surface side thin wire electrode 31 is formed on a back surface (hereinafter referred to as a back surface) provided on the opposite side of the light receiving surface of the photoelectric conversion unit 20. A large number of backside thin wire electrodes 31 are formed substantially in parallel over substantially the entire area of the backside. Since the back surface side of the solar cell 10 does not need to consider the reduction of the light receiving area, more thin wire electrodes than the light receiving surface side thin wire electrode 30 can be formed. By increasing the number of thin wire electrodes, electrical resistance loss on the back surface side can be reduced.

  The light receiving surface side thin wire electrode 30 and the back surface side thin wire electrode 31 according to the present embodiment are formed by thermosetting a thermosetting conductive paste. As the thermosetting conductive paste, for example, a silver paste in which silver particles are dispersed in an epoxy thermosetting resin solution can be used.

  The wiring member 40 is joined to the light receiving surface of one solar cell 10 and the back surface of another solar cell 10 (not shown in FIG. 2) adjacent to the one solar cell 10.

  FIG. 3 is an enlarged view of a portion A in FIG. 4 is a cross-sectional view taken along the line BB in FIG. As shown in FIG. 3, in the present embodiment, the wiring member 40 is disposed substantially orthogonal to the light receiving surface side thin wire electrode 30 formed substantially in parallel on the light receiving surface. The wiring member 40 is bonded to the light receiving surface by a resin adhesive 80.

  As shown in FIG. 4, the light-receiving surface side fine wire electrode 30 according to the present embodiment includes a first portion 30 a that is bonded to the wiring member 40 and a second portion 30 b that is not bonded to the wiring member 40. The height ha of the first portion 30a from the surface (light receiving surface) of the substrate is greater than the height hb of the second portion 30b from the light receiving surface. Further, the length W2 of the first portion 30a with respect to the extending direction of the light receiving surface side thin wire electrode 30 on the light receiving surface is smaller than the width W1 of the wiring member 40 joined to the first portion 30a. That is, the first portion 30 a is covered with the wiring member 40. Therefore, the contact area between the light receiving surface side thin wire electrode 30 and the wiring member 40 is increased.

  The wiring member 40 includes a low resistance body 41a such as a copper foil, and a conductor 41b plated on the outer periphery of the low resistance body 41a. In the present embodiment, solder (mainly tin) is used as the material of the conductor b constituting the wiring member 40. As the material of the conductor 41b, a material that is softer than the light receiving surface side thin wire electrode 30 is used at the temperature when the wiring member 40 is bonded to the surface of the solar cell 10, that is, the temperature at which the resin adhesive 80 is cured. . For example, as the conductor 41b, a soft conductive metal such as eutectic solder with a lowered melting point can be used.

  5 is a cross-sectional view taken along the line CC of FIG. As shown in FIG. 5, the first portion 30 a is embedded in the wiring material 40. Specifically, it is embedded in the conductor 41 b that forms the wiring member 40. Thereby, the 1st part 30a and the wiring material 40 are connected mechanically and electrically.

  6 is a cross-sectional view taken along the line DD in FIG. As shown in FIG. 6, the second portion 30 b that is not joined to the wiring member 40 is smaller in height from the light receiving surface of the photoelectric conversion unit 20 than the first portion 30 a. The width and thickness of the second portion 30b of the light receiving surface side thin wire electrode 30 are improved in yield and output characteristics of the solar cell module in consideration of the resistance value of the light receiving surface side thin wire electrode 30, the effective light receiving area of the solar cell 10, and the like. Is determined to be an optimum value.

  The first portion 30a may be embedded in the conductor 41b and further reach the low resistance body 41a. The width and thickness of the wiring member 40 are determined in consideration of the rigidity and resistance value of the wiring member 40 determined by the combination of the low resistance body 41a and the conductor 41b, the effective light receiving area of the solar cell 10, and the like. It is determined to an optimum value that can improve the output characteristics of the module.

  As shown in FIG. 5, a resin adhesive 80 (resin layer) is disposed on the light receiving surface side of the photoelectric conversion unit 20. The wiring member 40 is bonded to the photoelectric conversion unit 20 via a resin adhesive 80.

  As the resin adhesive 80, a strip-shaped film sheet mainly composed of an epoxy resin can be used. The resin adhesive 80 is blended with a crosslinking accelerator so that the crosslinking is rapidly accelerated by heating at a few tens of degrees and the curing is completed in about several tens of seconds. In FIG. 3, the width of the resin adhesive 80 is drawn with a greater emphasis than the width of the wiring member 40 for understanding the configuration. However, the width of the resin adhesive 80 does not unnecessarily shield incident light. In consideration of the above, it is preferable that the width is equal to or smaller than the width of the wiring member 40.

  In addition, although it demonstrated that the thing which has an epoxy resin as a main component was used as the resin adhesive 80, it can adhere | attach at the temperature lower than solder joining, Preferably, the temperature of 200 degrees C or less, Any material that can be cured in about 20 seconds may be used. For example, acrylic resins that have a low curing temperature and can contribute to the reduction of thermal stress, thermosetting resin adhesives such as polyurethane with high flexibility, thermoplastic resins such as EVA resins and synthetic rubbers, low temperature It is possible to use a two-component reaction adhesive or the like that can be bonded by mixing epoxy resin, acrylic resin, or urethane resin, which can be joined in the above, with a curing agent mixed.

  Further, the resin adhesive 80 may contain fine particles. The fine particles have an average particle size of about 10 μm, and nickel, gold-coated nickel, or a material obtained by mixing particles in which a conductive metal such as gold is coated on plastic can be used. The fine particles may be an insulating material.

  The configuration on the light receiving surface side of the photoelectric conversion unit 20 has been described above, but the back surface side is configured in the same manner as the light receiving surface side. That is, the first portion 31 a of the back surface side thin wire electrode 31 is embedded in the wiring material 40, and the wiring material 40 and the back surface of the photoelectric conversion unit 20 are joined by the resin adhesive 80.

(Method for manufacturing solar cell module)
Next, the manufacturing method of the solar cell module 1 which concerns on embodiment of this invention is demonstrated in detail with reference to drawings. Fig.7 (a) is sectional drawing explaining an example of the structure of the photoelectric conversion part 20 as a solar cell board | substrate.

  In creating the photoelectric conversion unit 20, the i-type amorphous silicon layer 20c and the p-type amorphous silicon layer 20b are sequentially formed on the light-receiving surface side of the n-type single crystal silicon substrate 20d using the CVD method. . Similarly, an i-type amorphous silicon layer 20e and an n-type amorphous silicon layer 20f are sequentially formed on the back side of the n-type single crystal silicon substrate 20d. Next, an ITO film 20a is formed on the light receiving surface side of the p-type amorphous silicon layer 20b by using a magnetron sputtering method. Similarly, an ITO film 20g is formed on the back side of the n-type amorphous silicon layer 20f.

  FIG. 7B is a plan view of the photoelectric conversion unit 20 viewed from the light incident direction. As shown in FIG. 7B, the light receiving surface of the photoelectric conversion unit 20 includes a first region α where the wiring member 40 is to be bonded and a second region β where the wiring member 40 is not bonded. The width of the first region α is substantially the same as the width of the wiring member 40. Similarly, the back surface of the photoelectric conversion unit 20 has a first region α and a second region β.

  With reference to FIG. 8, a process of forming a thin wire electrode having a first portion and a second portion on the substrate surface of the photoelectric conversion unit 20 will be described. When manufacturing the solar cell module 1 according to the present embodiment, a fine wire having a uniform height from the substrate surface along a direction substantially orthogonal to the longitudinal direction of the wiring member 40 bonded to the substrate surface of the photoelectric conversion unit 20. After a predetermined number of electrodes 30 are formed at a predetermined interval, the same material is formed on the thin wire electrode 30 in the first region α to increase the height.

  The height of the thin wire electrode 30 formed first from the substrate surface corresponds to the height hb of the second portion 30b. The first portion 30a having the height ha is formed by overlapping the same material on the thin wire electrode 30 formed at the height hb in the first region α.

  Specifically, a predetermined number of light receiving surface side thin wire electrodes 30 (second portions 30b) having a height hb from the light receiving surface are formed over the entire surface of the light receiving surface by screen printing using silver paste. Then, the silver paste is temporarily cured by heating at a temperature of a few hundred degrees for several minutes. Subsequently, similarly, a predetermined number of back-side thin wire electrodes 31 (second portions 31b) having a height hb from the back surface are formed at predetermined intervals on the back surface by screen printing, and at a temperature of hundreds of degrees for several minutes. The silver paste is temporarily cured by heating. Next, a region other than the light-receiving surface side fine wire electrode 30 formed in the first region α is masked, and a silver paste is superimposed on the thin wire electrode formed in the first region α by screen printing to increase the height from the light-receiving surface. A first portion 30a having a length ha is formed. Similarly, on the back surface, a region other than the back surface side thin wire electrode 31 formed in the first region α is masked, and silver paste is overlaid on the thin wire electrode formed in the first region α by screen printing to increase the height from the back surface. A first portion 31a having a length ha is formed. Thereafter, the first part 30a and the second part 30b (on the back surface, the first part 31a and the second part 31b) are cured by heating the silver paste on both sides for about 30 minutes at a temperature of a few hundred degrees.

  As described above, the light receiving surface side fine wire electrode 30 is formed on the light receiving surface of the photoelectric conversion unit 20 and the back surface side thin wire electrode 31 is formed on the back surface.

  In forming the first portion 30a and the second portion 30b, the second portion 30b having a height hb from the light receiving surface is first screen-printed in the second region β, and then the second region β is masked. Subsequently, the first portion 30a having the height ha in the first region α may be screen-printed.

  Next, a strip-shaped film sheet (resin adhesive 80) mainly composed of an epoxy resin is pasted on the first region α on the light receiving surface and the back surface of the photoelectric conversion unit 20. The width of the belt-shaped film sheet is set to be approximately the same as the width of the wiring member 40. The wiring member 40 is placed on the belt-shaped film sheet and lightly crimped.

  Next, the wiring member 40 is heated while being pressed in a direction perpendicular to the main surface of the photoelectric conversion unit 20 from the upper part. Specifically, it is set in an apparatus having a structure in which a heater block heated to a temperature of a few hundred degrees above and below, and a function of keeping the applied pressure constant. The photoelectric conversion unit 20 in which the wiring member 40 is temporarily bonded at a predetermined position is sandwiched between upper and lower heater blocks, and for example, a time required for curing the resin adhesive 80 by applying a pressure of about 2 MPa, for example, 15 seconds. The wiring member 40 is joined to the photoelectric conversion unit 20 by heating to the extent.

  During this heating, the first portion 30 a of the light receiving surface side thin wire electrode 30 is embedded in the conductor 41 b of the wiring member 40. Thereby, the light-receiving surface side fine wire electrode 30 is mechanically and electrically connected to the wiring member 40 in the first portion 30a.

  The conductor 41b forming the outer periphery of the wiring member 40 has a hardness of about ½ that of silver forming the light receiving surface side thin wire electrode 30 at room temperature. The hardness of the conductor 41b is further reduced when heated to a temperature of a few hundred degrees. Therefore, when the wiring member 40 disposed on the light receiving surface and the back surface of the photoelectric conversion unit 20 is uniformly pressed, the resin adhesive 80 is fluidly removed by the first portion 30a, and the first portion 30a becomes the wiring member. It is easily embedded in the conductor 41b forming 40. Similarly, on the back surface, the first portion 31 a of the back surface side thin wire electrode 31 is embedded in the conductor 41 b of the wiring material 40 and is mechanically and electrically connected to the wiring material 40.

  Next, the EVA sheet (sealing material 50) on the glass substrate (light-receiving surface side protective material 60), the plurality of solar cells 10 connected by the wiring material 40, the EVA sheet (sealing material 50), the back surface side protective material. 70 are sequentially laminated in this order to form a laminated body. The laminated body is subjected to thermocompression bonding in a vacuum atmosphere so as to be temporarily bonded, and then heated under predetermined conditions to completely cure EVA.

  The solar cell module 1 (refer FIG. 1) is manufactured by the above. Although not shown, the solar cell module 1 can be attached with an aluminum frame, a terminal box, and the like.

(Function and effect)
In the solar cell module 1 according to the embodiment of the present invention, the light receiving surface side thin wire electrode 30 has a first portion 30a and a second portion 30b, and the light receiving surface of the first portion 30a joined to the wiring member 40. Is higher than the height hb of the second portion 30b.

  FIG. 9 is a diagram for explaining the contact area between the wiring member 40 and the light receiving surface side fine wire electrode 30 in the solar cell module 1. In the solar cell module 1, if the light receiving surface side thin wire electrode 30 is uniformly formed at a height hb from the light receiving surface, the light receiving surface side thin wire electrode 30 embedded in the conductor 41b of the wiring member 40 is This is indicated by the dotted line in FIG. On the other hand, in the solar cell module 1 according to the present embodiment, the first portion of the thin wire electrode (including the first portion 30a of the light receiving surface side thin wire electrode 30 and the first portion 31a of the back surface side thin wire electrode 31) is a thin wire. The height from the substrate surface of the photoelectric conversion unit 20 is larger than the second portion of the electrode (including the second portion 30b of the light-receiving surface side thin wire electrode 30 and the second portion 31b of the back surface side thin wire electrode 31) (ha> hb), the contact area with the wiring member 40 increases.

  Thus, the solar cell module 1 can increase the contact area with the wiring member 40 as compared with the case of the thin wire electrode in which the height from the substrate surface of the photoelectric conversion unit 20 is uniformly formed. Thereby, when the solar cell module 1 manufactures a solar cell module by directly joining the wiring material to the fine wire electrode without forming the bus bar electrode, the contact resistance at the joint surface between the wiring material 40 and the fine wire electrode is reduced. be able to. Therefore, the output characteristics of the solar cell module can be improved.

  Further, in the solar cell module, when light reception and non-light reception are repeated in an actual usage environment, the sealing material 50 and the wiring material 40 repeat expansion and contraction. In general, since the linear expansion coefficient of the sealing material 50 is larger than the linear expansion coefficient of the wiring material 40, the stress generated at the interface between the second portion 30b and the sealing material 50 is the wiring between the first portion 30a and the wiring. It is larger than the stress generated at the interface with the material 40 (conductor 41b). That is, under the usage environment of the solar cell module, damage is more easily accumulated in the second portion 30b than in the first portion 30a. Therefore, the thickness and width size of the fine wire electrode are reduced in yield, good solar cell characteristics, etc. in consideration of the stress from the sealing material 50, the resistance of the fine wire electrode itself, the effective light receiving area of the solar cell, etc. Optimized to obtain.

  In the solar cell module 1 shown as the present embodiment, when the thickness and width size of the second portion 30b are optimized according to the stress from the sealing material 50, the resistance of the thin wire electrode itself, the effective light receiving area of the solar cell, and the like. The reduction of the contact area with the wiring member 40 which is a problem is solved by providing the first portion 30a.

  The difference between the height of the first portion of the fine wire electrode from the substrate surface and the height of the second portion of the fine wire electrode from the substrate surface takes into account the resistance of the fine wire electrode itself, the effective light receiving area of the solar cell, and the like. In addition, the second portion to be optimized and the layer thickness of the conductor 41b in the wiring member 40 should be determined.

  The size in the width direction and the thickness direction of the second portion 30b of the thin wire electrode is optimized as described above. However, since the height of the first portion 30a from the substrate surface of the photoelectric conversion unit 20 is larger than that of the second portion 30b, the length W2 of the first portion 30a is the length of the wiring member 40 bonded to the first portion 30a. When the width W1 is exceeded, the stress from the sealing material 50 is easily received. Therefore, in the solar cell module 1 shown as this embodiment, it is preferable that the 1st part 30a does not become larger than the width | variety of the wiring material 40 in the extension direction of a thin wire electrode. The first portion 30 a is preferably covered with the wiring material 40. Thereby, even if the height of the 1st part 30a is enlarged rather than the 2nd part 30b where the height from the substrate surface of the photoelectric conversion part 20 is optimized, it makes it difficult to receive the stress from the sealing material 50. be able to.

(Other examples)
Although the present invention has been described by using the above-described embodiments, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in the above embodiment, the solar cell substrate having the HIT structure has been described as an example. However, the present invention can also be applied to an ordinary crystalline solar cell substrate having no HIT structure.

  In the above embodiment, the light receiving surface side thin wire electrode 30 has been mainly described. However, the back surface side thin wire electrode 31 has the same effect. Therefore, in the thin wire electrode of either the light receiving surface side thin wire electrode 30 or the back surface side thin wire electrode 31, the first portion joined to the wiring material is closer to the surface of the photoelectric conversion unit than the second portion not joined to the wiring material. If the height is formed large, the effect of the present invention can be obtained.

  Moreover, although the low resistance body 41a of the wiring material 40 was demonstrated as a copper foil in the said embodiment, as a material of a wiring material, electrical resistance should just be small, iron, nickel, silver or these other than copper Can be used.

  Moreover, in the said embodiment, although the strip | belt-shaped film sheet is used as the resin adhesive 80, it does not need to be the adhesive shape | molded by the sheet form. For example, a resin adhesive may be applied to the first region α. Further, the resin adhesive 80 may not be arranged over the entire first region α. For example, the wiring member 40 and the light receiving surface side fine wire electrode 30 shown in FIGS.

  Moreover, although the said Example demonstrated the case where the wiring material 40 and the light-receiving surface side thin wire electrode 30 (or back surface side thin wire electrode 31) are substantially orthogonal, the wiring material 40 and the light receiving surface side thin wire electrode 30 (or) The back surface side thin wire electrode 31) should just be electrically connected, and should just cross | intersect at least.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is determined only by the invention specifying matters according to the scope of claims reasonable from the above description.

  Hereinafter, the solar cell module according to the present invention will be specifically described with reference to examples. The present invention is not limited to those shown in the following examples, and can be implemented with appropriate modifications within a range not changing the gist thereof.

Example 1
The solar cell module according to Example 1 was produced as follows. First, a 125 mm square solar cell substrate having a HIT structure was prepared. Next, using a screen printing method, a silver paste was applied in a predetermined pattern on the light-receiving surface side of the solar cell substrate, and was temporarily cured by heating at 150 ° C. for 5 minutes. Moreover, the silver paste was apply | coated to the back surface side of the solar cell board | substrate with the predetermined pattern, and it hardened by heating at 150 degreeC for 5 minute (s).

  Next, on the silver paste pattern formed in the first region using a screen printing method, masking other than the silver paste pattern in the first region on the light receiving surface side (the region where the wiring material is to be arranged) A silver paste having a predetermined thickness was applied on top of each other. Similarly, on the back side, the silver paste was further applied on the silver paste pattern formed in the first region. In addition, as silver paste, 5 vol. % Dispersed was used.

  At this time, a portion other than the first portion in the first region (in the region where the wiring material is to be arranged) is masked, and a predetermined thickness is formed on the pattern of the silver paste formed in the first region using a screen printing method. Silver paste was applied in layers. Similarly, on the back side, a silver paste having a predetermined thickness was applied over the silver paste pattern formed in the first region.

  In Example 1, the average difference between the height from the substrate surface of the first portion where the thin wire electrode is bonded to the wiring material and the height of the second portion not bonded to the wiring material is about 2.5 μm. The first part was overcoated with silver paste.

  Thereafter, the silver paste on both sides was heated at 200 ° C. for 30 minutes to crosslink and cure to form a fine wire electrode.

  Next, an epoxy resin adhesive was applied to substantially the entire first region of the photoelectric conversion portion, and a wiring material was disposed. As the wiring material, a copper wire (width 2 mm, thickness 150 μm) outer periphery coated with solder (thickness 30 μm) was used. The solar cell was thermocompression bonded under the conditions of 250 ° C. and 2 MPa with the wiring member joined.

  Thereafter, an EVA sheet, a plurality of solar cells connected by a wiring material, an EVA sheet, and a back film were sequentially laminated on the glass substrate in this order, and the plurality of solar cells were encapsulated in an EV resin by a vacuum thermocompression bonding method.

(Example 2)
A solar cell module according to Example 2 was produced as follows. In Example 2, the average difference between the height from the substrate surface of the first portion where the thin wire electrode is bonded to the wiring material and the height of the second portion not bonded to the wiring material is about 7.5 μm. The first part was overcoated with silver paste.

(Example 3)
A solar cell module according to Example 3 was produced as follows. In Example 3, the average difference between the height from the substrate surface of the first portion where the thin wire electrode is bonded to the wiring material and the height of the second portion not bonded to the wiring material is about 12.5 μm. The first part was overcoated with silver paste.

Example 4
A solar cell module according to Example 4 was produced as follows. In Example 4, the average of the difference between the height from the substrate surface of the first part where the thin wire electrode is joined to the wiring material and the height of the second part not joined to the wiring material is about 2.5 μm, which is the same as in Example 1. The silver paste was overcoated on the first part so that Moreover, when arrange | positioning a wiring material, the epoxy resin adhesive was apply | coated only to the cross | intersection part of a wiring material and a silver paste instead of the substantially whole area of the 1st area | region of a photoelectric conversion part.

(Comparative example)
Further, a solar cell module formed uniformly without any difference between the height of the first portion where the thin wire electrode is bonded to the wiring material from the substrate surface and the height of the second portion where the thin wire electrode is not bonded to the wiring material was used as a comparative example. .

The solar cell modules of Examples 1 to 4 and Comparative Example 1 described above were irradiated with light of AM 1.5 and 100 mW / cm ² from the light incident surface side of the solar cell module, and the output characteristics of the solar cell module. I investigated. The results are shown in Table 1. Table 1 shows the output decrease rate when the output decrease rate of the comparative example is 100.

  From the results shown in Table 1, the output reduction rate of the solar cell modules of Examples 1 to 4 is smaller than the output reduction rate of the comparative example. This is considered to be because the height from the substrate surface of the first portion where the thin wire electrode is bonded to the wiring material is higher than that of the second portion which is not bonded to the wiring material.

  Therefore, the output characteristics of the solar cell module can be improved by making the height from the substrate surface of the first portion where the thin wire electrode is bonded to the wiring material higher than the second portion not bonded to the wiring material. Was confirmed.

  Further, in Example 4, the average difference between the height from the substrate surface of the first portion where the thin wire electrode is bonded to the wiring material and the height of the second portion not bonded to the wiring material is the same as in Example 1. However, the reason why the output characteristics slightly decreased is that the adhesive strength of the wiring material to the photoelectric conversion portion decreased because the epoxy resin adhesive was partially applied.

  Therefore, the larger the difference between the height from the substrate surface of the first portion where the thin wire electrode is bonded to the wiring material and the height of the second portion not bonded to the wiring material, the more the output characteristics of the solar cell module can be improved. It was confirmed that it was possible.

It is sectional drawing which shows the structure of the solar cell module which concerns on embodiment of this invention. It is a top view of the solar cell in the said solar cell module. It is an enlarged view which expands and shows the A section of FIG. It is sectional drawing in the BB cut surface of FIG. It is sectional drawing in the CC cut surface of FIG. It is sectional drawing in the DD cut surface of FIG. (A) is sectional drawing explaining the structure of the photoelectric conversion part of the said solar cell module, (b) is the top view which looked at the photoelectric conversion part 20 from the light incident direction. It is explanatory drawing explaining the process of forming the thin wire | line electrode which has a 1st part and a 2nd part on the substrate surface of the photoelectric conversion part of the said solar cell module. It is a schematic diagram explaining the junction part of the wiring material and the light-receiving surface side fine wire electrode in the said solar cell module.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Solar cell module, 10 ... Solar cell, 20 ... Photoelectric conversion part, 30 ... Light-receiving surface side thin wire electrode, 30a ... 1st part, 30b ... 2nd part, 31 ... Back surface side thin wire electrode, 31a ... 1st part, 31b ... second part, 40 ... wiring material, 41a ... low resistance, 41b ... conductor, 50 ... sealing material, 60 ... light-receiving surface side protective material, 70 ... back surface side protective material, 80 ... resin adhesive

Claims (2)

A solar cell module comprising a light receiving surface side protective material, a back surface side protective material, and a plurality of solar cells connected to each other by a wiring material between the light receiving surface side protective material and the back surface side protective material,
The solar cell has a substrate and a plurality of thin wire electrodes formed on the surface of the substrate,
The wiring member and the solar cell are joined via a resin layer,
The wiring material is arranged so as to intersect with the thin wire electrode,
The fine wire electrode has a first portion joined to the wiring material at the intersecting portion and a second portion not joined to the wiring material,
The solar cell module, wherein a height of the first portion from the surface of the substrate is larger than a height of the second portion from the surface of the substrate.   The solar cell module according to claim 1, wherein the first portion is covered with the wiring member.

Images