TWI467787B - Solar battery module and manufacturing method thereof - Google Patents

Description

Solar battery module and manufacturing method thereof

The present invention relates to a solar battery module in which a resin adhesive is disposed between a wiring material and a main surface of a solar cell, and a method of manufacturing the same.

The present application claims priority from Japanese Patent Application No. P2007-20265, filed on Aug. 2, 2007, and Japanese Patent Application No. P2007-341070, filed on Dec. 28, 2007. The entire contents of the case are used in this application.

Solar cells are expected to be used as new energy sources because they can directly convert sunlight, which is clean and can be supplied without restriction, into electricity.

Generally, the output of each solar cell is about several W (watts). Therefore, when a solar battery is used as a power source for a house or a building, a solar battery module in which a plurality of solar cells are connected to increase the output can be used. The solar battery module is configured by connecting a plurality of solar cells arranged in the first direction to each other by using a wiring material. The wiring material is usually soldered to the main surface of the solar cell.

Here, there is proposed a resin adhesive which thermally hardens a temperature lower than a melting temperature of a soft solder to be interposed between a wiring material and a main surface of a solar cell, so that the wiring material is thermally followed (hot) Gluing) is a technique of the main surface of a solar cell (for example, refer to Japanese Laid-Open Patent Publication No. 2005-101519).

If this technique is used, when compared with the case where the wiring material is soldered In a relatively short period of time, the influence of the temperature change of the heat of the wiring material on the solar cell can be reduced.

Here, in general, since the surface of the wiring material is flat, when the wiring material is thermally bonded to the main surface of the solar cell, the same pressure is applied to the resin adhesive. Therefore, the gas sealed in the resin adhesive can be easily removed from the central portion of the resin adhesive although it can be easily removed from the end portion of the resin adhesive. Therefore, there is a fear that the gas sealed in the central portion of the resin adhesive is agglomerated by a block (void). As a result, the bonding area between the wiring material and the solar cell is reduced, and as a result, there is a problem that the current collecting efficiency of the solar cell is lowered and the adhesion of the wiring material is lowered.

Accordingly, the present invention has been made in view of the above problems, and an object thereof is to provide a solar cell module and a manufacturing method thereof for improving the current collecting efficiency of a solar cell and the adhesion of a wiring material by promoting degassing from a resin adhesive. method.

The solar battery module according to the first aspect of the present invention includes the first and second solar cells arranged along the first direction, and the wiring material electrically connecting the first and second solar cells to each other. The first and second solar cells are a photoelectric conversion unit that generates a light forming carrier by receiving light, and a light conversion unit formed on the main surface of the photoelectric conversion unit to generate light. a current collecting collector electrode of the carrier, and the wiring material is disposed on the main surface of the first and second solar cells along the first direction, and the wiring material and the first and second solar cells Between the main faces The resin adhesive is formed in a convex shape on the cut surface substantially perpendicular to the first direction, and the outer periphery of the wiring material is oriented toward the first and second solar cells, and is in a second direction substantially perpendicular to the first direction. The width of the connection region of the region electrically connected to the collector electrode as the wiring material is larger than approximately half of the width of the wiring material.

In the first aspect of the present invention, the collector electrode may include a plurality of fine electrode electrodes for collecting the light generating carrier from the photoelectric conversion unit, and collecting the light generated carrier wave from the thin wire electrode. a bus-bar electrode, the bus bar electrode is formed along the first direction, the wiring material is disposed on the bus bar electrode, and the resin adhesive comprises a plurality of conductive The particles and the connection region are formed of particles contained in the resin binder. Further, it is preferable that the bus bar electrode has a protruding portion which is formed in a convex shape toward the wiring material, and the protruding portion is caught in the wiring material.

In the first aspect of the present invention, the collector electrode may include a plurality of thin wire electrodes for collecting the light generating carrier from the photoelectric conversion portion, and the connection region may be formed by embedding a part of the thin wire electrode in the wiring material. .

A method of manufacturing a solar cell module according to a second aspect of the present invention includes the first and second solar cells arranged along the first direction, and the first and second solar cells are electrically connected to each other In the wiring material, the main electrode of the photoelectric conversion unit that generates the light-generating carrier by light is formed with a collector electrode for collecting the light-generating carrier, and the first and second solar cells are produced. And on the main surfaces of the first and second solar cells, the wiring material is passed along the first layer via a resin adhesive Step B of hot pressure welding is performed in one direction, and the outer circumference of the wiring material is formed in a convex shape toward the first and second solar cells on the cut surface substantially perpendicular to the first direction. In the step B, the width of the connection region of the region electrically connected to the collector electrode as the wiring material in the second direction substantially perpendicular to the first direction is made larger than approximately half of the width of the wiring material.

According to the manufacturing method of such a solar cell module, the outer periphery of the wiring material is formed in a convex shape toward the collector electrode. Therefore, in the thermocompression bonding step of the wiring material, first, pressure is applied to the central portion of the resin adhesive in the second direction, and then pressure is gradually applied to the end portion. That is, the end portion of the resin adhesive is slightly delayed in time from the center portion.

Therefore, the gas sealed in the resin adhesive can be slowly extruded from the center portion toward the end portion. That is, the deaeration of the resin adhesive proceeds slowly from the center portion to the end portion. Since the degassing of the resin adhesive is promoted in this manner, it is possible to suppress the agglomeration of the gas in the resin adhesive after the thermocompression bonding step of the wiring material.

Further, in the thermocompression bonding step of the wiring material, since the width of the connection region is made larger than approximately half of the width of the wiring material, the electrical connection between the wiring material and the collector electrode can be sufficiently ensured.

In the second aspect of the present invention, the resin adhesive may include a plurality of particles having conductivity, and in step B, the particle diameter of the particles contained in the resin adhesive may be a predetermined particle diameter or more. Thereby, the width of the connection area is made larger than approximately half of the width of the wiring material.

In the second feature of the present invention, in the step B, the wiring material may be The pressure at the time of thermocompression bonding on the main surfaces of the first and second solar cells is set to a predetermined pressure or more, whereby the width of the connection region is made larger than approximately half of the width of the wiring material.

Next, an embodiment of the present invention will be described using the drawings. In the following description of the drawings, the same or similar parts are attached to the same or similar symbols. However, the drawings are merely illustrative, and it is necessary to pay attention to the fact that the ratios of the respective dimensions are different from the actual ones. Therefore, the specific dimensions and the like need to be judged by referring to the following description. Moreover, the drawings mutually include portions having different sizes or ratios of each other.

1. First embodiment (Summary structure of solar cell module)

The schematic configuration of the solar battery module 100 according to the first embodiment of the present invention will be described with reference to Fig. 1 . Fig. 1 is an enlarged side view showing the solar battery module 100 of the present embodiment.

The solar battery module 100 includes a solar cell string 1, a light-receiving surface side protective material 2, a back side protective material 3, and a sealing material 4. The solar cell module 100 is configured by sealing the solar cell string 1 between the light-receiving surface side protective material 2 and the back side protective material 3.

The solar cell string 1 includes a plurality of solar cells 10, a wiring material 11, and a resin adhesive 12. The solar cell string 1 is composed of a plurality of solar cells 10 arranged in the first direction and connected to each other by a wiring member 11.

The solar cell 10 has a light receiving surface on which sunlight is incident, and is disposed on The back side of the opposite side of the light receiving surface. The light receiving surface and the back surface are the main faces of the solar cell 10. A collector electrode is formed on the light receiving surface and the back surface of the solar cell 10. The configuration of the solar battery 10 will be described later.

The wiring member 11 is joined to a collector electrode formed on a light receiving surface of one solar cell 10, and a collector electrode formed on the back surface of another solar cell 10 adjacent to one solar cell. Thereby, one solar cell 10 is electrically connected to another solar cell 10. The wiring material 11 includes a thin plate-shaped low-resistance body (such as copper) and a soft conductor (eutectic soft solder) which is plated on the surface of the low-resistance body.

The resin adhesive 12 is disposed between the wiring member 11 and the solar cell 10. That is, the wiring member 11 is bonded to the solar cell 10 via the resin adhesive 12. The resin adhesive 12 is preferably hardened below the melting point of the eutectic soft solder, that is, at a temperature of about 200 ° C or lower. As the resin adhesive 12, in addition to a thermosetting resin adhesive such as an acrylic resin or a highly flexible polyurethane, two kinds of hardeners mixed with an epoxy resin, an acrylic resin, or a polyurethane may be used. The liquid reaction is an adhesive or the like. In the present embodiment, as the resin adhesive 12, a strip-shaped film sheet adhesive containing an epoxy resin as a main component is used.

Further, the resin adhesive 12 contains a plurality of particles having conductivity. As the conductive particles, nickel, nickel coated with a gold coating, or the like can be used.

The light-receiving side protective material 2 is disposed on the light-receiving surface side of the sealing material 4 to protect the surface of the solar cell module 100. As the light-receiving surface side protective material 2, a light transmissive and water-shielding glass, a translucent plastic, or the like can be used.

The back side protective material 3 is disposed on the back side of the sealing material 4 to protect the back surface of the solar cell module 100. As the back side protective material 3, a laminated film having a structure in which a resin film such as PET (polyethylene terephthalate) or an aluminum (Al) foil is interposed with a resin film can be used.

The sealing material 4 seals the solar cell string 1 between the light-receiving surface side protective material 2 and the back side protective material 3. As the sealing material 4, EVA (ethylene-vinyl acrylate copolymer), EEA (ethylene-ethyl acrylate copolymer), PVB (polydivinyl alcohol butyral), polyfluorene oxide, polyurethane, polyacrylic acid can be used. A translucent resin such as an ester or a polyepoxy resin.

Further, an aluminum (Al) frame (not shown) may be attached to the outer periphery of the solar battery module 100 having the above configuration.

(composition of solar cells)

Next, the configuration of the solar cell 10 will be described with reference to Fig. 2 . Fig. 2 is a plan view of the solar cell 10.

As shown in FIG. 2, the solar cell 100 includes a photoelectric conversion unit 20, a thin wire electrode 30, and a bus bar electrode 40.

The photoelectric conversion unit 20 is a person who generates a light generation carrier due to sunlight. The light generating carrier is intended to mean a positive hole and an electron generated by the sunlight being absorbed by the photoelectric conversion unit 20. The photoelectric conversion unit 20 has an n-type area and a p-type area therein, and a semiconductor junction (semiconductor junction) is formed at an interface between the n-type region and the p-type region. . As the photoelectric conversion unit 20, a crystalline semiconductor material such as single crystal Si or polycrystalline Si, GaAs (gallium arsenide), or the like can be used. A semiconductor substrate composed of a semiconductor material such as a compound semiconductor material such as InP (indium phosphide). Here, the photoelectric conversion portion 20 may have a structure in which an intrinsic amorphous germanium layer is substantially sandwiched between a single crystal germanium substrate and an amorphous germanium layer to improve the characteristics of a hetero-junction interface. That is, the HIT structure.

The thin wire electrode 30 is an electrode that collects electricity from the photogeneration unit 20 from the photoelectric conversion unit 20. As shown in FIG. 2, the thin wire electrode 30 is formed in a line shape along a second direction substantially perpendicular to the first direction. The thin wire electrode 30 covers a substantially entire area of the light receiving surface of the photoelectric conversion unit 20 to form a plurality of branches. The thin wire electrode 30 can be formed by using a resin material as a binder and a resin-type conductive paste in which conductive particles such as silver particles are used as a filler. Here, as shown in FIG. 1, the thin wire electrode 30 is formed similarly on the light receiving surface and the back surface of the photoelectric conversion unit 20.

The bus bar electrode 40 is an electrode that collects light from a plurality of thin wire electrodes 30. As shown in FIG. 2, the bus bar electrode 40 is formed along the first direction so as to intersect the thin wire electrode 30. The bus bar electrode 40 can be formed using a resin-based conductive paste containing a conductive material such as silver particles as a filler, using a resin material as an adhesive. Here, the bus bar electrode 40 will also be formed on the back surface of the photoelectric conversion unit 20 (refer to FIG. 1).

Here, the number of branches of the bus bar electrode 40 can be set to an appropriate number in consideration of the size of the photoelectric conversion unit 20 and the like. The solar cell 10 of the present embodiment includes two bus bar electrodes 40. Therefore, a plurality of fine The wire electrode 30 and the bus bar electrode 40 are formed in a lattice shape on the light receiving surface and the back surface of the photoelectric conversion unit 20.

Next, as an example of the configuration of the solar battery 10, the photoelectric conversion unit 20 has an HIT structure, and will be described with reference to FIG. Fig. 3 is an enlarged cross-sectional view taken along line A-A of Fig. 2;

As shown in FIG. 3, the photoelectric conversion unit 20 includes an ITO (indium tin oxide) film 20a, a p-type amorphous germanium layer 20b, an i-type amorphous germanium layer 20c, and an n-type single crystal germanium substrate 20d and i. The amorphous germanium layer 20e, the n-type amorphous germanium layer 20f, and the ITO film 20g.

A p-type amorphous germanium layer 20b is formed on the light-receiving surface side of the n-type single crystal germanium substrate 20d via the i-type amorphous germanium layer 20c. An ITO film 20a is formed on the light-receiving surface side of the p-type amorphous germanium layer 20b. On the other hand, an n-type amorphous germanium layer 20f is formed on the back surface side of the n-type single crystal germanium substrate 20d via the i-type amorphous germanium layer 20e. An ITO film 20g is formed on the back side of the n-type amorphous germanium layer 20f.

The thin wire electrode 30 and the bus bar electrode 40 are formed on the light receiving surface side of the ITO film 20a and the back surface side of the ITO film 20g, respectively.

The solar cell module 100 having the solar cell 10 thus constructed is referred to as an HIT solar cell module.

(constitution of solar cell string)

Next, the configuration of the solar battery string 1 will be described with reference to Figs. 4 and 5 . Fig. 4 shows a state in which the wiring member 11 is disposed on the bus bar electrode 40 shown in Fig. 2. Fig. 5 is an enlarged cross-sectional view taken along line B-B of Fig. 4.

As shown in Fig. 4, the resin adhesive 12 is disposed on the bus bar electrode 40 which is formed linearly along the first direction. In the fourth embodiment, the width of the resin adhesive 12 in the second direction is larger than the width of the bus bar electrode 40, but is not particularly limited thereto.

Further, the wiring member 11 is placed on the resin adhesive 12 and disposed along the bus bar electrode 40. That is, the wiring member 11 is disposed on the main surface of the solar cell 10 along the first direction. The width of the wiring member 11 in the second direction is substantially the same as the width of the bus bar electrode 40.

In this manner, the bus bar electrode 40, the resin adhesive 12, and the wiring member 11 are sequentially disposed on the photoelectric conversion unit 20. The wiring material 11 and the bus bar electrode 40 are electrically connected.

As shown in Fig. 5, the wiring member 11 includes a low-resistance body 11a, a soft conductor 11b, and a soft conductor 11c. The soft conductor 11b is located between the low-resistance body 11a and the solar cell 10, and the soft conductor 11c is located on the low-resistance body 11a. The width of the wiring material 11 in the second direction is W2.

In the third direction which is substantially perpendicular to the main surface of the solar cell 10, that is, in the thickness direction, the thickness T1 of the soft conductor 11b becomes smaller as it goes from the second direction toward the end in the second direction. Therefore, in the cut surface that is substantially perpendicular to the first direction, the outer circumference of the wiring member 11 is formed to be convex toward the solar cell 10. As shown in Fig. 5, the wiring member 11 has the same outer shape on the light-receiving surface side and the back surface side.

A resin adhesive 12 is interposed between the wiring member 11 and the solar cell 10. In the resin adhesive 12, a plurality of particles having conductivity are contained 13. As shown in Fig. 5, a plurality of particles 13 include particles 13 embedded in the soft conductor 11b, particles 13 sandwiched by the soft conductor 11b and the bus bar electrode 40, or embedded therein. The particles 13 in the resin adhesive 12.

In the present embodiment, a region where the soft conductor 11b and the bus bar electrode 40 are electrically connected is referred to as a connection region C. The connection region C is formed by the particles 13 embedded in the soft conductor 11b and the particles 13 sandwiched by the soft conductor 11b and the bus bar electrode 40. Therefore, the connection region C means a region on the cut surface substantially perpendicular to the first direction, and the interval between the soft conductor 11b and the bus bar electrode 40 is substantially equal to or smaller than the particle diameter of the particles 13.

Here, the width W1 of the connection region C in the second direction is larger than approximately half (W2/2) of the width W2 of the wiring member 11. That is, the distance between the particles 13 sandwiched between the soft conductor 11b and the bus bar electrode 40 at both ends of the connection region C is larger than approximately half of the width W2 of the wiring member 11.

(Method of manufacturing solar cell module)

Next, a method of manufacturing the solar cell module 100 of the present embodiment will be described.

First, an anisotropic etching process of a 100 mm square n-type single crystal germanium substrate 20d is performed using an aqueous alkali solution, whereby fine unevenness is formed on the light receiving surface of the n-type single crystal germanium substrate 20d. Further, the light-receiving surface of the n-type single crystal germanium substrate 20d is washed to remove impurities.

Next, on the light-receiving side of the n-type single crystal germanium substrate 20d, In the CVD (chemical vapor deposition) method, the i-type amorphous germanium layer 20c and the p-type amorphous germanium layer 20b are sequentially laminated. Similarly, an i-type amorphous germanium layer 20e and a p-type amorphous germanium layer 20f are sequentially laminated on the back side of the n-type single crystal germanium substrate 20d.

Next, an ITO film 20a is formed on the light-receiving surface side of the p-type amorphous germanium layer 20b by a PVD (physical vapor deposition) method. Similarly, an ITO film 20g is formed on the back side of the n-type amorphous germanium layer 20f. The photoelectric conversion unit 20 can be manufactured as described above.

Next, an epoxy-based thermosetting silver paste is applied to the light-receiving surface and the back surface of the photoelectric conversion unit 20 by a printing method such as a screen printing method or an offset printing method. , configured in a predetermined pattern. As shown in Fig. 2, the predetermined pattern is a lattice shape formed by two bus bar electrodes 40 extending in the first direction and a plurality of thin wire electrodes 30 extending in the second direction.

The silver paste is heated under predetermined conditions to evaporate the solvent, and then heated to carry out the drying. In the above, the solar cell 10 can be fabricated.

Next, as shown in Fig. 6, thermocompression bonding of the wiring member 11 is performed on the bus bar electrode 40 via a resin adhesive 12 containing a plurality of particles 13. Thereby, the wiring material 11 and the solar cell 10 are mechanically and electrically connected. Specifically, first, the resin adhesive 12 and the wiring member 11 are sequentially disposed on the bus bar electrode 40 formed on the light receiving surface and the back surface of the photoelectric conversion unit 20, respectively. Next, the wiring member 11 is pressed toward the solar cell 10 for about 15 seconds using a heater block 50 heated to about 180 °C. Thereby, a plurality of particles 13 That is, it is buried in the soft conductor 11b, and is sandwiched between the soft conductor 11b and the bus bar electrode 40.

In addition, the Mohs hardness of the silver paste which is a material of the particle 13 , the soft solder which is a material of the soft conductor 11 b, and the silver paste which is a material of the bus bar electrode 40 are 3.5, 8, and 2.5, respectively. Therefore, the particles 13 can be buried in the soft electric conductor 11b as a result of pressing the wiring material 11 against the solar cell 10.

Here, the electrical connection between the wiring member 11 and the solar cell 10 is performed by the connection region C in which the interval between the soft conductor 11b and the bus bar electrode 40 is substantially equal to or smaller than the particle diameter of the particles 13.

In the present embodiment, the width W1 of the connection region C is made larger than approximately half of the width W2 of the wiring member 11 in the second direction.

Specifically, if the width W1 of the connection region C is to be made larger than approximately half of the width W2 of the wiring member 11, the following three methods can be employed.

The first method is a method in which the pressure of the wiring member 11 is pressed against the solar battery 10 by using the heater unit 50, and is set to a predetermined value or more.

In the second method, the particle size of the particles 13 contained in the resin adhesive 12 is set to a predetermined particle diameter or more.

In the third method, the curvature of the outer circumference of the wiring member 11 on the cut surface that is substantially perpendicular to the first direction is made small. That is, the third method is to use a method close to the flat as the wiring material 11. Specifically, the speed at which the low-resistance body 11a is pulled from the plating bath of the soft conductor 11b or the mold extrusion used when pulling the plating bath from the plating bath is changed. The shape of the dies is used to control the curvature of the outer circumference of the wiring material 11.

In the actual pressure bonding step, the pressure of the pressing heater unit 50, the particle diameter of the particles 13 and the curvature of the outer circumference of the wiring member 11 are integrally formed and interlocked, so that the width W1 of the connection region C can be made larger. Approximately half of the width W2 of the wiring member 11 is large.

By the above method, the solar cell string 1 can be formed.

Next, on the glass substrate (light-receiving side protective material 2), EVA (sealing material 4) sheet, solar cell string 1, EVA (sealing material 4) sheet, and PET sheet (back side protective material) are laminated in this order. 3) Make a laminate.

Next, the laminate is heated and pressure-bonded in a vacuum atmosphere to be temporarily pressure-bonded, and then heated under predetermined conditions to completely cure the EVA. By the above method, the solar cell module 100 can be manufactured.

Further, on the solar battery module 100, a terminal box or an Al frame or the like can be mounted.

(action and effect)

According to the method of manufacturing the solar cell module 100 of the present embodiment, in the step of thermocompression bonding of the wiring member 11 via the resin adhesive 12 containing the particles 13 on the main surface of the solar cell 10, the wiring is used as the wiring. The width W1 of the connection region C in the region where the material 11 and the bus bar electrode 40 are electrically connected is made larger than approximately half of the width W2 of the wiring member 11. The outer circumference of the wiring member 11 is formed in a convex shape toward the bus bar electrode 40 on a cut surface that is substantially perpendicular to the first direction.

As described above, the outer circumference of the wiring member 11 is formed in a convex shape toward the bus bar electrode 40. Therefore, in the thermocompression bonding step, first, the resin is connected. After the pressure is applied to the central portion of the agent 12 in the second direction, pressure is gradually applied to the end portion. That is, the end portion of the resin adhesive 12 is pressurized after being delayed in time from the central portion.

Therefore, the gas which is closed in the resin adhesive 12 is slowly extruded from the center portion to the end portion. That is, the deaeration of the resin adhesive 12 is gradually performed from the center portion toward the end portion. As described above, since the degassing of the resin adhesive 12 can be promoted, it is possible to suppress the gas agglomeration in the resin adhesive 12 after the thermocompression bonding step from becoming a void and remaining.

Further, in the thermocompression bonding step, the width W of the connection region C is made larger than approximately half of the width W2 of the wiring member 11. Therefore, the electrical connection between the wiring member 11 and the solar cell 10 (the bus bar electrode 40) can be sufficiently ensured.

As a result of the above-described practice, the current collecting efficiency of the solar cell 10 or the adhesion to the solar cell 10 (the bus bar electrode 40) of the wiring member 11 can be improved.

Further, in the present embodiment, the connection region C is formed by a plurality of particles 13. Therefore, the connection region C is a cut surface that is substantially perpendicular to the first direction, and the interval between the soft conductor 11b and the bus bar electrode 40 is approximately equal to or smaller than the particle diameter of the particles 13.

Therefore, when the pressure of the wiring member 11 against the solar cell 10 is set to a predetermined value or more by using the heater unit 50, the width W1 of the connection region C can be made substantially larger than the width W2 of the wiring member 11. When the wiring material 11 is pressed against the solar cell 10 (the bus bar electrode 40) with a large pressure, the soft electric conductor 11b is deformed, and the connection can be increased. The width W of the area C.

In addition, when the particle diameter of the particles 13 contained in the resin adhesive 12 is set to a predetermined particle diameter or more, the width W1 of the connection region C can be made larger than approximately half of the width W2 of the wiring member 11. The connection region C is a region in which the distance between the soft conductor 11b and the solar cell 10 (the bus bar electrode 40) is substantially equal to or smaller than the particle diameter of the particles 13. Thus, if the particle diameter of the particles 13 is increased, the width W1 of the connection region C can be increased.

Further, when the curvature of the outer circumference of the wiring member 11 which is to be cut along the first direction is made small, the width W1 of the connection region C can be made larger than approximately half of the width W2 of the wiring member 11. When the wiring material 11 is close to a flat shape, the interval between the wiring material 11 and the solar cell 10 (the bus bar electrode 40) can be made larger than the width of the region which is substantially equal to or smaller than the particle diameter of the particles 13.

2. Second embodiment

Next, a second embodiment of the present invention will be described with reference to the drawings. This embodiment is different from the above-described first embodiment in that the bus bar electrode has a protruding portion that protrudes toward the wiring material. In the following, the description of the same or similar parts as those of the above-described first embodiment will be omitted.

(constitution of solar battery strings)

The configuration of the solar battery string 1 of the present embodiment will be described with reference to Fig. 7. Fig. 7 is an enlarged cross-sectional view taken along line B-B of Fig. 4.

As shown in Fig. 7, regarding the bus bar electrode 40 of the present embodiment, There is a projection 40a formed in a convex shape toward the wiring member 11. The protruding portion 40a is formed at an end portion of the bus bar electrode 40 in the second direction. The protruding portion 40a is caught in the soft conductor 11b of the wiring member 11. The height of the projection 40a in the third direction is preferably substantially equal to the thickness T1 of the soft conductor 11b. Such a projection 40a can be formed by the following first to third methods.

In the first method, when the bus bar electrode 40 is formed by the screen printing method on the photoelectric conversion unit 20, the method of increasing the distance between the frame of the fixed screen and the photoelectric conversion unit 20 is increased.

First, the photoelectric conversion unit 20 and the frame are fixed at a predetermined interval. Next, the silver paste is extruded from the opening portion of the screen onto the photoelectric conversion portion 20. At this time, the screen is pressed against the photoelectric conversion unit 20 by the squeegeing roller, and then rebounds to the original position.

Here, the screen has a portion in which the opening portion of the wire which is stretched in a lattice shape on the frame body is filled with the emulsion, and a portion in which the emulsion is incomplete in the shape of the bus bar electrode 40. Therefore, when the screen rebounds, the silver paste is embossed by the wire mesh stretching at the boundary between the portion where the emulsion is formed and the portion where the emulsion is incomplete. Therefore, at the end of the bus bar electrode 40, the protrusion 40a will be formed. In such a projection 40a, the larger the rebound of the screen, that is, the larger the interval between the frame of the fixed screen and the photoelectric conversion unit 20, the higher the formation.

The second method is a method of increasing the printing speed when the bus bar electrode 40 is formed by the screen printing method on the photoelectric conversion unit 20. The printing speed means the moving speed of the flattening roller when the silver paste is extruded from the opening portion of the screen to the photoelectric conversion portion 20.

If the moving speed of the flattening roller is increased, the screen will rebound more quickly. When the screen is quickly rebounded, the silver paste is stretched by the screen at the boundary between the portion where the emulsion is formed and the portion where the emulsion is incomplete. Thus, at the end of the bus bar electrode 40, the projection 40a is formed. Such a protrusion 40a, such as a screen, is more rapidly rebounded, that is, the higher the printing speed is, the higher the height can be formed.

In the third method, when the bus bar electrode 40 is formed by the screen printing method on the photoelectric conversion unit 20, the viscosity of the silver paste as the material of the bus bar electrode 40 is improved. As described above, the silver paste is embossed together with the screen on the boundary between the portion where the emulsion is formed and the portion where the emulsion is incomplete. At this time, the higher the viscosity of the silver paste, the easier it is to be stretched by the screen. That is, as the viscosity of the silver paste is increased, the protrusion 40a can be increased.

Further, in the present embodiment, as shown in Fig. 7, the outer circumference of the wiring member 11 is formed in a convex manner toward the bus bar electrode 40, and the width W1 of the connection region C in the second direction is compared. Approximately half of the width W2 of the wiring member 11 is large.

(action and effect)

In the solar battery module 100 of the present embodiment, as in the first embodiment, the outer circumference of the wiring member 11 is formed in a convex manner toward the bus bar electrode 40 on the cut surface substantially perpendicular to the first direction. As a result, the width W1 of the connection region C is larger than approximately half of the width W2 of the wiring member 11.

Therefore, in the step of connecting the wiring member 11, in addition to the degassing of the resin adhesive 12, the electrical connection between the wiring member 11 and the bus bar electrode 40 can be achieved in the connection region C.

Further, in the solar battery module 100 according to the present embodiment, the bus bar electrode 40 has an end portion formed in the second direction of the bus bar electrode 40 toward the wiring member 11, and is caught in the wiring member 11.

Thus, since the protruding portion 40a is trapped in the wiring member 11, the wiring material 11 and the bus bar electrode 40 can be improved in addition to the mechanical connection strength between the wiring member 11 and the bus bar electrode 40. Electrical connection between. As a result, the current collecting efficiency of the solar cell 10 and the adhesion of the wiring material 11 can be further improved.

3. Third embodiment

Next, a third embodiment of the present invention will be described using the drawings. The present embodiment differs from the above-described first embodiment in that the solar cell of the present embodiment does not include a bus bar electrode as a collector electrode. Therefore, in the following description, the description of the same or similar parts as those of the above-described first embodiment will be omitted.

(Summary structure of solar cell module)

The schematic configuration of the solar cell 200 of the present embodiment will be described with reference to Fig. 8. Fig. 8 is an enlarged side view showing the solar battery module 200 of the present embodiment.

The solar battery module 200 is formed between the light-receiving surface side protective material 2 and the back side protective material 3, and is sealed by the sealing material 4 to seal the solar battery string 60.

The solar battery string 60 includes a plurality of solar cells 70, a wiring material 11, and a resin adhesive 72. The solar battery string 60 is formed as a plurality of solar cells 70 arranged in the first direction, and is interconnected using the wiring material 11. The method of connecting is formed.

The resin adhesive 72 is a strip-shaped film sheet adhesive containing an epoxy resin as a main component. However, the resin adhesive 72 does not contain particles having conductivity.

The other configuration is the same as that of the first embodiment described above.

(composition of solar cells)

Next, the configuration of the solar battery 70 will be described with reference to Fig. 9. Fig. 9 is a plan view showing the light receiving surface side of the solar cell 70.

As shown in FIG. 9, the solar battery 70 includes a photoelectric conversion unit 20 and a thin wire electrode 30. The solar cell 70 does not have a bus bar electrode as a collector electrode.

The other configuration is the same as that of the first embodiment described above.

(constitution of solar battery strings)

Next, the configuration of the solar battery string 60 will be described with reference to Figs. 10 to 12 . Fig. 10 is a view showing a state in which the wiring material 11 is disposed on the solar cell 70. Figure 11 is an enlarged cross-sectional view taken along line D-D of Figure 10. Fig. 12 is an enlarged cross-sectional view taken along line E-E of Fig. 10.

As shown in Fig. 10, the resin adhesive 72 is attached to the solar cell 70, and two of them are arranged along the first direction. Further, the wiring member 11 is placed on the resin adhesive 72 and arranged along the first direction. The width of the wiring member 11 in the second direction is narrower than the width of the resin adhesive 72.

As described above, in the solar cell 70, the resin adhesive 72 and the wiring member 11 are sequentially arranged.

As shown in Fig. 11, the wiring member 11 includes a low resistance body 11a, a soft conductor 11b, and a soft conductor 11c. The width of the wiring material 11 in the second direction is W2.

In the third direction substantially perpendicular to the main surface of the solar cell 70, the thickness T1 of the soft conductor 11b is reduced from the center portion in the second direction toward the end portion. In other words, the outer periphery of the wiring member 11 is formed in a convex shape toward the solar cell 70 on the cut surface substantially perpendicular to the first direction.

As shown in Fig. 12, the upper end portion of the thin wire electrode 30 is buried in the soft conductor 11b. That is, a part of the thin wire electrode 30 is buried in the wiring material 11. Therefore, the thin wire electrode 30 and the wiring material 11 can be electrically and mechanically connected to each other.

In the present embodiment, as shown in Figs. 11 and 12, a region where the thin wire electrode 30 and the soft conductor 11b are electrically connected is referred to as a connection region F. The connection region F is formed by a part of the thin wire electrode 30 being buried in the wiring member 11.

Here, the width W1 of the connection region F in the second direction is larger than approximately half of the width W2 of the wiring member 11 as shown in FIG.

(Method of manufacturing solar cell module)

Next, a method of manufacturing the solar battery module 200 of the present embodiment will be described.

First, the photoelectric conversion unit 20 similar to that described in the first embodiment is produced.

Next, an epoxy-based thermosetting silver paste is applied to the light-receiving surface and back of the photoelectric conversion unit 20 by a printing method such as a screen printing method or a lithography method. On the surface, a plurality of coatings are applied along the second direction. Next, the silver paste is heated under predetermined conditions to evaporate the solvent, and then heated to carry out the drying. The thin wire electrode 30 is formed in this manner. According to the above method, the solar cell 70 can be fabricated.

Next, thermosetting of the wiring member 11 is performed on the solar cell 70 via the resin adhesive 72. Thereby, the wiring material 11 and the solar cell 70 are mechanically and electrically connected. Specifically, first, the resin adhesive 72 and the wiring member 11 are sequentially disposed on the light receiving surface and the back surface of the photoelectric conversion unit 20, respectively. Next, the wiring member 11 is pressed toward the solar cell 70 for about 15 seconds using a heater assembly heated to about 180 °C.

The electrical connection between the wiring material 11 and the solar cell 70, that is, the region where the thin wire electrode 30 is partially buried in the wiring material 11, that is, by the connection region F. Here, in the present embodiment, the width W1 of the connection region F in the second direction is made larger than approximately half of the width W2 of the wiring member 11.

Specifically, if the width W1 of the connection region F is to be made larger than approximately half of the width W2 of the wiring member 11, the following two methods can be employed.

In the first method, the heater element 50 is used to press the wiring material 11 against the pressure of the solar cell 70 to form a predetermined value or more.

In the second method, the curvature of the outer circumference of the wiring member 11 on the cut surface which is substantially perpendicular to the first direction is made small. That is, as the wiring material 11, a method of using a flatter is used. Specifically, the speed at which the low-resistance body 11a is pulled from the plating bath of the soft conductor 11b, or the electric power is changed. The shape of the mold extrusion die used when the plating bath is pulled is used to control the curvature of the outer circumference of the wiring material 11.

In the actual crimping step, the pressure of the pressing heater assembly 50 and the curvature of the wiring member 11 are integrated as a whole, and the width W1 of the connection region F can be made larger than the width W2 of the wiring member 11. Half is big. From the above, the solar cell string 60 can be fabricated.

Next, on the glass substrate (light-receiving side protective material 2), EVA (sealing material 4) sheet, solar cell string 60, EVA (sealing material 4) sheet, and PET sheet (back side protective material) are laminated in this order. 3) Make a laminate.

Next, the laminate is heated and pressure-bonded in a vacuum atmosphere to be temporarily pressure-bonded, and then heated under predetermined conditions to completely cure the EVA. By the above method, the solar cell module 200 can be manufactured.

Further, on the solar battery module 200, a terminal box, an Al frame, or the like can be mounted.

(action and effect)

According to the manufacturing method of the solar cell module 200 of the present embodiment, in the step of thermocompression bonding of the wiring member 11 via the resin adhesive 72 on the main surface of the solar cell 70, the wiring material 11 and the thin wire electrode are used. The width W1 of the connection region F for electrically connecting 30 is made larger than approximately half of the width W2 of the wiring member 11. The outer circumference of the wiring member 11 is formed in a convex shape toward the bus bar electrode 40 on a cut surface that is substantially perpendicular to the first direction.

As described above, the outer circumference of the wiring member 11 is formed in a convex shape toward the bus bar electrode 40. Therefore, in the thermocompression bonding step, first, the resin is connected. After the pressure is applied to the central portion of the agent 72 in the second direction, pressure is gradually applied to the end portion. Therefore, the deaeration of the resin adhesive 72 is gradually performed from the center portion toward the end portion. As a result, the degassing of the resin adhesive 72 can be promoted, and the gas agglomeration in the resin adhesive 72 after the thermocompression bonding step can be suppressed from remaining as a void.

Further, in the thermocompression bonding step, the width W1 of the connection region F is made to be substantially half the width W2 of the wiring member 11. Therefore, the electrical connection between the wiring member 11 and the solar cell 70 (the thin wire electrode 30) can be sufficiently ensured.

As a result of the above, the current collecting efficiency of the solar cell 70 and the adhesion between the wiring material 11 and the solar cell 70 (the thin wire electrode 30) can be improved.

(Other embodiments)

The content of the present invention is described by the above-described embodiments, but it should not be construed that the present invention is defined by the description and the drawings which constitute a part of the disclosure. Those skilled in the art will be able to devise various alternative embodiments, embodiments, and applications.

Further, in the above-described embodiment, a plurality of thin wire electrodes 30 are formed on the back surface of the photoelectric conversion portion 20, but they may be formed so as to cover the entire back surface. The present invention is not limited to the shape of the thin wire electrode 30 formed on the back surface of the photoelectric conversion portion 20.

Further, in the first embodiment, the width of the resin adhesive 12 in the second direction is larger than the width of the bus bar electrode 40 in the second direction, but may be substantially the same or small.

Further, in the second embodiment, the projection 40a is formed to be soft. The thickness T1 of the conductor 11b is small, but the height of the protrusion 40a may be made larger than the thickness T1 of the soft conductor 11b. That is, the protruding portion 40a can also reach the low resistance body 11a.

Further, in the third embodiment, the width of the resin adhesive 72 in the second direction is larger than the width of the wiring member 11 in the direction of the second direction, but it may be substantially equal or smaller.

As such, the present invention can of course encompass various embodiments and the like not described in the disclosure. Therefore, it is apparent from the above description that the technical scope of the present invention is appropriately determined by the specific matters of the invention of the patent application.

[Examples]

Hereinafter, the embodiment of the solar cell used in the solar cell module of the present invention will be specifically described, but the present invention is not limited to the examples shown in the following embodiments, and it is still within the scope of not changing the gist of the invention. It can be implemented as appropriate.

Examples 1 to 8 and Comparative Examples 1 to 5 were prepared in accordance with Table 1 below.

(Example)

First, a photoelectric conversion unit was produced using an n-type single crystal germanium substrate having a size of 100 mm square.

On the light-receiving surface and the back surface of the photoelectric conversion portion, an epoxy-based thermosetting silver paste is used, and a thin wire electrode and a bus bar electrode are formed in a comb shape by a screen printing method. The thickness (height) of the bus bar electrode was 50 μm and the width was 1.5 mm. The solar cell is made in this way.

Next, a wiring material in which a SnAgCu (tin-silver-copper) tin solder was plated into a convex shape was prepared on the upper and lower surfaces of a flat copper foil having a width of 1.5 mm. Specifically, the thickness of the wiring material in the central portion and the end portion in the width direction is different from each other in the respective examples as shown in Table 1.

Mold extrusion by changing the member for pulling the copper foil from the tin solder bath Control of the thickness of the wiring material is performed by the shape of the mold.

Next, an epoxy resin-based adhesive is applied to the bus bar electrode formed on the light receiving surface of one solar cell and the bus bar electrode formed on the back surface of another adjacent solar cell. As the epoxy resin-based adhesive, about 50,000 nickel particles were kneaded in an epoxy resin of 1 mm ³ . The particle diameter of the nickel particles was set in each of the examples as shown in Table 1.

Next, a wiring material is placed on the epoxy resin-based adhesive.

Next, the metal head heated to 200 ° C was heated for 60 seconds while being pressurized from the upper and lower sides of the wiring material. The pressing force of the metal head was set in each of the examples as shown in Table 1.

The solar cells of Examples 1 to 8 were fabricated as described above.

(Comparative example)

The solar cell strings of Comparative Examples 1 to 5 of the present invention were produced in accordance with Table 1 above. The difference in the manufacturing method between the comparative example and the above-described embodiment is the thickness of the wiring material in the central portion and the end portion in the width direction, the particle diameter of the nickel particles, and the setting of the heating pressure of the metal head.

The other steps are the same as those of the above embodiment.

(measurement of output)

Hereinafter, the results of measuring the outputs of the solar cells of Examples 1 to 8 and Comparative Examples 1 to 5 were examined after referring to Table 1 before and after the heat of the wiring material was performed.

In Table 1, the output ratio refers to the relative value of the solar cell output before the heat of the wiring material is followed by the heat output of the wiring material.

Further, in Examples 1 to 8 and Comparative Examples 1 to 5, the width of the connection region where the wiring material and the bus bar electrode were electrically connected was measured. Here, the connection region means a region in which the interval between the tin solder and the bus bar electrode is substantially equal to or smaller than the particle diameter of the nickel particles. Table 1 shows the relative values of the width of the connection region in the second direction to the width of the wiring material.

From the results of Comparative Examples 1, 2 and Examples 1 and 2, it was confirmed that the connection region can be increased by increasing the pressure of the wiring material. Further, it has been confirmed that the more the connection region is increased, the more the output of the solar cell is suppressed from being lowered. This is a result of reducing the contact resistance between the wiring material and the bus bar electrodes by the increase of the connection region.

Also, from the results of Examples 3 to 6, it was confirmed that the decrease in the output of the solar cell can be suppressed by increasing the pressure of the wiring material and increasing the connection area.

Further, when the results of Examples 1 and 2, Examples 3 to 6, and Comparative Examples 3 and 4 were compared, it was confirmed that when the particle diameter of the nickel particles was increased, the decrease in the output of the solar cell was suppressed. This is because the connection region is such that the interval between the tin solder and the bus bar electrode is substantially equal to or smaller than the particle diameter of the nickel particles. Here, the connection region is formed of nickel particles in an epoxy resin-based adhesive.

When the results of Comparative Example 2 and Examples 7 and 8 were compared, it was confirmed that the smaller the difference in thickness between the central portion and the end portion of the tin solder, the more the connection region can be increased. This is because the closer the wiring material is to the flat shape, the more the width of the connection region formed by the nickel particles is increased.

On the other hand, from the result of Comparative Example 5, it was confirmed that the wiring material was as follows. When formed into a flat shape, the connection area will be significantly smaller. As a result, the thermal compression of the wiring material causes a significant decrease in the output of the solar cell. This is because the wiring material is formed into a flat shape, and the degassing of the epoxy resin-based adhesive cannot be promoted, so that the gas agglomerates in the epoxy resin-based compound become voids and remain. That is, in Examples 1 to 8, degassing of the epoxy resin-based adhesive can be promoted.

1, 60‧‧‧ solar battery string

2‧‧‧Light-side protective material

3‧‧‧Back side protective material

4‧‧‧ Sealing material

10‧‧‧Solar battery

11‧‧‧Wiring materials

11a‧‧‧Low resistance body

11b, 11c‧‧‧ soft conductor

12, 72‧‧‧ resin adhesive

13‧‧‧ particles

20‧‧‧Photoelectric Conversion Department

20a, 20g‧‧‧ ITO film

20b‧‧‧p-type amorphous germanium layer

20c, 20e‧‧‧i type amorphous layer

20d, 20f‧‧‧n type single crystal germanium substrate

30‧‧‧ Thin wire electrode

40‧‧‧ Bus bar electrode

40a‧‧‧Protruding

50‧‧‧heater assembly

70‧‧‧Solar battery

100, 200‧‧‧ solar battery module

C, F‧‧‧ connection area

W1, W2‧‧‧ width

Fig. 1 is a side view showing a solar battery module 100 according to a first embodiment of the present invention.

Fig. 2 is a plan view showing a solar cell 10 according to the first embodiment of the present invention.

Figure 3 is a cross-sectional view taken along line A-A of Figure 2;

Fig. 4 is a view showing a state in which the bus bar electrode 40 of Fig. 2 is joined to the wiring material 11.

Fig. 5 is an enlarged cross-sectional view taken along line B-B of Fig. 2;

Fig. 6 is a schematic view for explaining a method of manufacturing the solar battery module 100 according to the first embodiment of the present invention.

Fig. 7 is an enlarged cross-sectional view showing a solar cell module 100 according to a second embodiment of the present invention.

Fig. 8 is a side view showing a solar battery module 200 according to a third embodiment of the present invention.

Fig. 9 is a plan view showing a solar cell 10 according to a third embodiment of the present invention.

Figure 10 is a view showing a solar cell 10 according to a third embodiment of the present invention. A schematic view of the state in which the wiring material 11 is bonded.

Figure 11 is a cross-sectional view taken along line D-D of Figure 10.

Fig. 12 is a cross-sectional view taken along line E-E of Fig. 10.

1‧‧‧Sun battery string

2‧‧‧Light-side protective material

3‧‧‧Back side protective material

4‧‧‧ Sealing material

10‧‧‧Solar battery

11‧‧‧Wiring materials

12‧‧‧Resin Adhesive

100‧‧‧Solar battery module

Claims (7)

A solar battery module comprising: first and second solar cells arranged along a first direction; and wiring materials electrically connecting the first and second solar cells to each other, wherein: The first and second solar cells have a photoelectric conversion portion that generates a light generation carrier by receiving light, and a collector electrode that is formed on the main surface of the photoelectric conversion portion to collect the light generation carrier, and the wiring material is used. Provided on the main surface of the first and second solar cells along the first direction, and a resin adhesive is disposed between the wiring material and the main surfaces of the first and second solar cells. The cut surface on the cut surface substantially perpendicular to the first direction, the outer circumference of the wiring material is formed in a convex shape toward the first and second solar cells, and is formed in the second direction substantially orthogonal to the first direction. The width of the connection region of the region where the wiring material is electrically connected to the collector electrode is larger than approximately half of the width of the wiring material; and the wiring material is on the cut surface substantially perpendicular to the first direction. They are: in contact with the convex portions collecting electrode; and a non-contact portion, and the line separating the resin adhesive interposed therebetween and with the collector electrode and the collector electrode followed. Such as the solar cell module of claim 1 of the patent scope, wherein the aforementioned set The electric electrode includes a plurality of thin wire electrodes that perform current collection of the light generating carrier from the photoelectric conversion unit, and a bus bar electrode that collects the light generating carrier from the thin wire electrode, and the bus bar electrode is along the bus bar electrode In the first direction, the wiring material is disposed on the bus bar electrode, and the resin adhesive includes a plurality of particles having conductivity, and the connection region is composed of the particles contained in the resin adhesive. Formed. The solar battery module according to claim 2, wherein the bus bar electrode has a protruding portion that is formed in a convex shape toward the wiring material, and the protruding portion is formed in the second direction of the bus bar electrode At the end portion, the protruding portion is caught in the wiring material. The solar battery module according to the first aspect of the invention, wherein the current collecting electrode includes a plurality of thin wire electrodes for collecting the light generating carrier from the photoelectric conversion portion, wherein the connection region is formed by the thin wire electrode A part is formed by being buried in the wiring material. A method for manufacturing a solar cell module, comprising: a first and a second solar cell arranged along a first direction; and a wiring material electrically connecting the first and second solar cells to each other To: The manufacturing method has: a step S of forming the current collecting electrodes for collecting the light generating carrier on the main surface of the photoelectric conversion portion that generates the light generating carrier by light, thereby producing the first and second solar cells, and the first step And a step B of thermally bonding the wiring material along the first direction via a resin adhesive on a main surface of the second solar cell, and on a cut surface substantially perpendicular to the first direction The outer circumference of the wiring material is formed with a convex portion toward the first and second solar cells, and in the step B, the wiring material and the current collecting are performed in a second direction substantially perpendicular to the first direction. The width of the connection region of the region where the electrodes are electrically connected is formed to be larger than approximately half of the width of the wiring material; and the convex portion of the wiring material and the aforementioned set are formed on the cut surface substantially perpendicular to the first direction Electrode contact; the non-contact portion of the wiring material is separated from the collector electrode and is connected to the collector electrode via the resin adhesive; and the thermocompression bonding is performed on the convex portion of the wiring material Melting points for the following. The method of manufacturing a solar cell module according to claim 5, wherein the resin adhesive comprises a plurality of particles having conductivity, and in the step B, the particles contained in the resin adhesive are The particle size is set to a predetermined particle diameter or more, whereby the aforementioned connection region is The width is made larger than approximately half of the width of the wiring material. The method of manufacturing a solar cell module according to claim 5, wherein in the step B, a pressure at which the wiring material is thermocompression bonded to the main surfaces of the first and second solar cells is set to a predetermined value Above the pressure, the width of the connection region is made larger than approximately half of the width of the wiring material.