JP2006332451A - Solar battery cell, solar battery module and method for manufacturing solar battery module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar battery cell for preventing the generation of the fracture, chip and crack of a substrate, and a method for manufacturing the solar battery module. <P>SOLUTION: This solar battery cell is provided with a light receiver 14 formed on a substrate surface, a surface electrode connected to the light receiver 14 and formed on the substrate surface 12, and a back electrode formed on a substrate rear face 13. The solar battery cell is provided with a connection connected to the back electrode so as to be driven from the substrate rear face to the outside of the substrate; and the connection is constituted as a metallic foil where an inter-layer with metal whose elastic modulus is smaller than that of copper as main components is interposed between two surface layers with copper as main components, so that the connection 21 can be constituted as a metallic foil whose elastic module is smaller than that of copper. Thus, it is possible to relax the distortion of a joint where each electrode is connected to the connection 21, and to prevent the generation of the fracture, chip and crack of the substrate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solar battery cell, a solar battery module, and a method for manufacturing a solar battery module, and more particularly to a solar battery cell, a solar battery module, and a method for manufacturing a solar battery module that are characterized by connecting portions that connect the solar battery cells.

  A conventional solar battery cell will be described with reference to FIGS.

  FIG. 11A is a perspective view of a conventional solar battery cell, and FIG. 11B is a side view of the conventional solar battery cell.

  A plurality of solar battery cells 101 are juxtaposed and connected to each other by a connecting part 121 to form a solar battery module (not shown).

  In the solar cell 101, a light receiving part 114 is provided on the surface of the substrate 111, and a surface electrode 116 for taking out light output is provided on the surface of the light receiving part 114. A back surface electrode 117 is provided on the back surface 113 of the substrate, and a reinforcing member 181 made of resin is attached to the back surface 113 of the substrate in order to prevent the substrate 111 from cracking (see Japanese Patent Application Laid-Open No. 2003-69055).

  One end of the connecting portion 121 is connected to the back electrode 117 with solder, and the other end is connected to the surface electrode 116 of the adjacent solar battery cell 101 with solder (not shown).

The connection part 121 is formed of copper having high conductivity in order to efficiently transmit electricity generated by the solar battery cell 101.
JP 2003-69055 A

  However, when the back electrode 117 and the connection portion 121 are connected by solder, warpage occurs at the solder joint, and cracks, cell cracks, and the like occur in the substrate 111.

  FIG. 12 is an explanatory diagram for explaining the warpage of the substrate in the region where the back electrode of the conventional solar battery cell and the connection portion are joined.

  A connecting portion 121 is connected to the back electrode 117 by solder. The substrate 111 is warped toward the connecting portion 121 in the region where the back electrode 117 is formed. In order to simplify the explanation of the warp, the connection part 121 on the surface electrode 116 side is not shown.

  The substrate 111 is made of silicon, and the connection part 121 is made of copper. The thermal expansion coefficient of copper is larger than that of silicon. For this reason, when the board | substrate 111 and the connection part 121 are heated and solder-joined, the board | substrate 111 and a connection part are in the state which the thermal expansion of the connection part 121 was large with respect to the board | substrate 111, and had a thermal expansion difference. 121 is fixed. Thereafter, when the solder joint cools and returns to room temperature, the connection portion 121 is smaller than the substrate 111, but the joint surface between the substrate 111 and the connection portion 121 is fixed. Since there is no displacement, the substrate 111 is pulled by the connecting portion 121 and warps toward the connecting portion 121. At this time, distortion occurs in the joint portion where the substrate 111 and the connection portion 121 are joined, and a crack is formed inside the substrate 111. Further, the substrate warpage and internal cracks cause cell cracks.

  In addition, the distortion of the joint, substrate warpage, internal cracks, etc., increase in degree due to temperature changes during the heat treatment in the manufacturing process, causing substrate cracks, chips, cracks, etc., which cause a decrease in production yield It becomes.

  In addition, since the substrate repeatedly expands and contracts due to daily temperature changes in the actual usage environment of the solar cell module, the degree of expansion, cracking of the substrate, distortion of the joint, substrate warpage, internal cracks, etc. It causes chipping, cracking, and the like, and causes deterioration in the quality and reliability of the solar battery cell.

  The present invention has been made in view of these points, and an object thereof is to manufacture a solar battery cell, a solar battery module, and a solar battery module in which distortion of the solar battery cell junction, substrate warpage, and internal cracks are prevented. It is to provide a method.

  A solar battery cell of the present invention includes a light receiving portion formed on a substrate surface, a surface electrode connected to the light receiving portion and formed on the substrate surface, and a back electrode formed on the back surface of the substrate. A connecting portion connected to the back surface electrode and led out from the back surface of the substrate to the outside of the substrate, wherein the connecting portion is provided with a covering portion extending over the back surface of the substrate, the main component being copper. The metal foil is characterized by sandwiching an intermediate layer mainly composed of a metal having a smaller elastic coefficient than copper between the two surface layers.

  With this configuration, a metal foil having a smaller elastic modulus than copper is bonded to the back electrode and the front electrode, so the distortion of the bonding portion between each electrode and the connection portion is alleviated, and the substrate warpage is reduced, Internal cracks are reduced. In addition, even if there is a temperature change during the heat treatment in the manufacturing process, and even if the temperature of the usage environment of the solar cell module may change repeatedly, the connection portion is a low elastic modulus material, Since stress due to thermal expansion and contraction can be relieved, generation of cracks, chips, cracks and the like of the substrate can be prevented.

  In addition, since the connection portion is composed of a layer mainly composed of copper on the front surface and the back surface, and the solder connectivity is good on both surfaces, one surface is a back electrode and the other surface is an adjacent solar cell. It is possible to make good solder connection with the surface electrode. That is, when the connecting portion has a two-layer structure and only one layer is copper, the connecting portion needs to be twisted 180 degrees when connecting the back surface electrode of the substrate and the surface electrode of the adjacent solar battery cell. However, when the connecting portion has the above structure, it is not necessary to perform such work.

  Further, since the entire back surface of the substrate is reinforced with the covering portion, it is possible to prevent cracking of the solar battery cell.

  Further, since the covering portion extends from the connection portion, it is not necessary to separately add a covering portion to the connection portion, so that the manufacturing process can be simplified. Moreover, since what was made into the connection part and the coating | coated part and separate parts can be made into one part, material procurement property improves. Moreover, since a coating | coated part will cover a substrate back surface, even if it is a case where a photovoltaic cell substrate is cracked, the light output of the broken part of a board | substrate can be collected.

  The intermediate layer of the metal foil preferably contains aluminum as a main component.

  With this configuration, it is possible to reduce the elastic modulus of the connecting portion while ensuring a certain conductivity. Moreover, although the main component of an intermediate | middle layer is good also as gold or silver, metal foil can be manufactured cheaply by having aluminum as a main component.

  Moreover, it is preferable to arrange | position the periphery of a coating | coated part inside the periphery of a substrate back surface.

  With this configuration, since the covering portion does not protrude from the peripheral edge of the back surface of the substrate, the covering portions of the adjacent solar cells are not brought into contact with each other, and a short circuit between the solar cells can be prevented.

  Moreover, it is preferable to form a plurality of backside electrodes in a discrete manner.

  With this configuration, the connection portion between the back electrode and the connection portion can be dispersed to reduce the distortion of the junction between the back electrode and the connection portion, thereby preventing the occurrence of cracks, chips, cracks, etc. on the substrate. Can do.

  Moreover, it is preferable that the connection portion has a step portion at a portion led out of the substrate.

  With this configuration, in the connection from the back surface electrode to the front surface electrode of the adjacent solar battery cell, the bending strain generated during the connection can be reduced, so that the strain and cracks of the connection portion can be reduced. In addition, in the case of using a straight connection portion that does not have a step portion, it is necessary to deform the connection portion with respect to the step difference in the thickness of the substrate when connecting to the surface electrode of the adjacent solar battery cell. However, since this operation can be omitted, the manufacturing process can be made more efficient.

  The back surface of the substrate is preferably covered with a reinforcing member made of resin so as to cover the covering portion.

  With this configuration, the solar cell substrate is reinforced by the reinforcing member, so that the solar cell can be prevented from cracking.

  Moreover, it is preferable that the solar cell module of the present invention is a solar cell module by connecting a plurality of the above-described solar cells.

  With this configuration, it is possible to prevent the occurrence of distortion, substrate warpage, internal cracks, etc. at the junctions of the front and back electrodes in individual solar cells, so the failure rate of the entire solar cell module is dramatically reduced. Can be made.

  Further, the method for manufacturing a solar cell module of the present invention includes a light receiving portion formed on the substrate surface, a surface electrode connected to the light receiving portion and formed on the substrate surface, a back electrode formed on the back surface of the substrate, A method for manufacturing a solar cell module comprising a plurality of solar cells connected to a back surface electrode and a connection portion having an extension portion that is led out from the back surface of the substrate. The connecting portion is a metal foil sandwiched between two surface layers mainly composed of copper and an intermediate layer mainly composed of a metal having a smaller elastic coefficient than copper, and a solder layer is provided on each surface of the front electrode and the back electrode. Forming and contacting the contact region of the connecting portion with the back surface electrode, contacting the extension portion with the front surface electrode of the adjacent solar battery cell, and heating the contact region and the back surface electrode. And the extension and the surface electrode Characterized by bonding.

  With this configuration, since the connecting portion that connects the back electrode and the front electrode can be a metal foil having a smaller elastic modulus than copper, the distortion of the solder joint that occurs in the heating process is alleviated, the substrate warp, and Production yield can be improved by reducing internal cracks and the like.

  According to the solar cell according to the present invention, the connecting portion for connecting the back electrode and the front electrode of the substrate of the solar cell is made of a metal having a smaller elastic modulus than copper in two surface layers mainly composed of copper. By sandwiching the intermediate layer as the main component, the elastic modulus of the connection portion is made smaller than the elastic modulus of the copper foil, and thereby, the distortion of the joint portion of the solar battery cell, the substrate warp, the internal crack, etc. Generation | occurrence | production can be suppressed and the crack of a board | substrate of a photovoltaic cell, a chip, a crack, etc. can be prevented.

  Moreover, since the coating | coated part which covers a board | substrate back surface is provided in the connection part, since the whole photovoltaic cell can be reinforced, generation | occurrence | production of the crack of a photovoltaic cell can also be prevented by this.

  Further, since the covering portion extends from the connecting portion, it is not necessary to perform the joining of the connecting portion and the bonding of the covering portion in separate steps, and the manufacturing process of the solar battery cell can be simplified. .

  Moreover, according to the solar cell module according to the present invention, it is possible to prevent cracking, chipping, cracking, etc. of the substrate of the solar cell that is the configuration of the solar cell module, so that the failure rate of the entire solar cell module is significantly reduced. be able to.

  In addition, according to the method for manufacturing a solar cell module according to the present invention, the solar cell can be reduced by reducing the distortion of the joint, the warpage of the substrate, the internal crack, and the like that occur between the substrate and the connection portion that occur in the heating process of manufacture. Since the substrate can be prevented from cracking, chipping, cracking, etc., the production yield can be improved. Moreover, since the covering portion is made of a metal foil integrally with the connecting portion, it is not necessary to perform the joining of the connecting portion and the bonding of the covering portion in separate steps, thereby simplifying the manufacturing process of the solar battery cell. Can do.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

<Embodiment 1>
FIG. 1A is a perspective view of the solar battery cell according to Embodiment 1 of the present invention as viewed from the substrate surface side, and FIG. 1B is the back surface of the solar battery cell according to Embodiment 1 of the present invention. It is the perspective view seen from the side. FIG. 2 is a cross-sectional view along the arrow AA of the solar battery cell shown in FIG.

  The solar cell 1 is formed on a semiconductor substrate 11 made of a P-type silicon wafer, a light receiving portion 14 formed on the substrate surface 12, a surface electrode 16 formed on the light receiving portion 14, and a substrate back surface 13. It is composed of a back electrode 17 and a connection part 21 connected to the back electrode 17 and leading out of the substrate. In addition, the coating | coated part 22 extended from the connection part 21 has covered the board | substrate back surface 13 (refer FIG. 1 (B)).

  The substrate 11 includes a P-type silicon layer 30, an N-type semiconductor layer 31 is formed on the surface thereof, and a PN junction 39 is formed at the boundary between the P-type silicon layer 30 and the N-type semiconductor layer 31. An uneven layer 32 for promoting the absorption of sunlight is formed on the surface of the N-type semiconductor layer 31, and an antireflection film 33 for preventing the reflection of sunlight is formed on the surface of the uneven layer 32. ing. The surface electrode 16 is formed so as to protrude from the uneven layer 32 to the surface of the light receiving portion. The surface electrode 16 is made of silver, and a solder layer 46 is formed on the surface thereof.

On the surface of the P-type silicon layer 30 opposite to the surface on which the N-type semiconductor layer 31 is formed, a P ⁺ -type semiconductor layer 34 is formed by baking aluminum paste. The back electrode 17 is formed in a partial region of the P ⁺ type semiconductor layer 34. The back electrode 17 is made of silver, and a solder layer 47 is formed on the surface thereof.

  The outer shape of the substrate 11 is formed in a rectangular shape, for example, in plan view by dicing.

  FIG. 3A is a bottom view showing the back surface pattern of the substrate according to the first embodiment of the present invention, and FIG. 3B shows another back surface pattern of the substrate according to the first embodiment of the present invention. It is a bottom view shown.

  A plurality of backside electrodes 17 are formed discretely. In FIG. 2A, the back electrode 17 pattern is formed by forming two rectangular back electrodes 17 in parallel on one side of the substrate back surface 13 at a distance from each other.

  In FIG. 5B, the back electrode 17 pattern has a plurality of back electrodes 17 formed along the outer edge of the substrate back surface 13.

  FIG. 4 is a perspective view of the connecting portion according to Embodiment 1 of the present invention.

  The connection portion 21 includes a main body portion 21a, an extension portion 21b, and a covering portion 22, and is provided with a covering portion 22 that extends from the main body portion 21a and covers the back surface 13 of the substrate, and is integrally formed with a metal foil. ing. The main body portion 21a is integrated with the covering portion 22 and has a rectangular shape. The main body portion 21 a is provided with a contact area 23 that contacts the back electrode 17.

  The extension portion 21b is a portion extended from the main body portion 21a, and is configured to be led out of the substrate on the substrate back surface 13 when the covering portion 22 is attached to the substrate back surface 13 (FIG. 1B). )reference). The tip of the extension portion 21 b is connected to the surface electrode 16 of the adjacent solar battery cell 1. The length of the extension part 21b should just be the length which reaches the surface electrode 16 of the adjacent photovoltaic cell 1. FIG.

  Moreover, the extension part 21b may be one or plural. When the number of the extension portions 21b increases, the area of the light receiving portion 14 is reduced correspondingly, which is disadvantageous from the viewpoint of light output. On the other hand, when one is used, the entire solar cell module operates when the extension portion 21b is disconnected. It will not be reliable. Therefore, in the present embodiment, two are formed to ensure reliability.

  The outer periphery of the covering portion 22 is rectangular, for example, and the size thereof is smaller than the area of the substrate back surface 13, and the outer periphery of the covering portion 22 is inward of the outer periphery of the substrate back surface 13 when contacting the substrate back surface 13. It is formed to become.

  For example, the covering portion 22 has a shape that is smaller by 0.2 mm to 2.0 mm from the periphery of the back surface 13 of the substrate. By this structure, since the coating | coated part 22 does not protrude from the board | substrate back surface 13 periphery, the coating | coated parts 22 of the adjacent photovoltaic cell 1 do not contact, and the short circuit between the photovoltaic cells 1 can be prevented. . The width of 0.2 mm to 2.0 mm is set in consideration of the alignment variation when the cover 22 is attached to the back surface 13 of the substrate.

  FIG. 5 is an explanatory diagram for explaining the adhesion between the back surface of the substrate and the covering portion in the first embodiment according to the present invention.

  The covering portion 22 is attached to the main body portion 21a of the connecting portion 21 so as to cover the entire back surface 13 of the substrate.

  Thereby, since the board | substrate back surface 13 whole is reinforced with the coating | coated part 22 and the main-body part 21a, the crack of the photovoltaic cell 1 can be prevented. In addition, since the covering portion 22 is provided with the connecting portion 21 extending, it is not necessary to adhere the covering portion 22 to the main body portion 21a in a separate process, and thus the manufacturing process can be simplified. Moreover, since what was made into the connection part 21 and the coating | coated part 22 and separate components can be made into one component, material procurement property improves.

  The contact area 23 contacts the back electrode 17 and is joined by solder. Since the contact region 23 and the back electrode 17 have different thermal expansion coefficients, stress is generated at the joined portion. This stress increases as the area of the joint portion increases. Since a plurality of back surface electrodes 17 are formed discretely, the joint portion between the contact region 23 and the back surface electrode 17 is dispersed, and the joining stress between the connection portion 21 and the back surface electrode 17 is dispersed. As a result, the strain due to the bonding between the back electrode 17 and the connection portion 21 can be reduced, and the occurrence of cracks, chips, cracks, etc. of the substrate can be prevented.

  A region around the contact region 23 (a region obtained by removing the contact region 23 from the covering portion 22 and the main body portion 21 a) is bonded to the substrate back surface 13 by the heat-sensitive adhesive 51. The heat-sensitive adhesive 51 increases the adhesive force when heated and adheres the adherend.

  FIG. 6 is a perspective view of a connecting portion provided with a step portion in the first embodiment of the present invention.

  The connection portion 21 is provided with a step portion 29 corresponding to the thickness of the substrate 11 of the solar battery cell 1. With this configuration, in the connection from the back surface electrode 17 to the front surface electrode 16 of the adjacent solar battery cell 1, it is possible to alleviate the bending distortion that occurs at the time of connection, thereby reducing the strain and cracks of the connection portion 21. be able to. Further, in the case of using the straight connection portion 21 not provided with the step portion 29, when connecting to the surface electrode 16 of the adjacent solar battery cell 1, the connection portion 21 with respect to the step difference of the substrate thickness. However, since this work can be omitted, the manufacturing process can be made more efficient.

  7 is a cross-sectional view taken along arrows BB of the connecting portion shown in FIG.

  The connection portion 21 has a three-layer structure, and is a metal foil in which an intermediate layer 26 mainly composed of a metal having a smaller elastic modulus than copper is sandwiched between two surface layers 25 and 27 mainly composed of copper. Yes.

  Since the connection portion 21 is a metal foil having a smaller elastic modulus than the copper foil, the distortion of the portion where the back electrode 17 and the main body portion 21a of the connection portion 21 are solder-connected is alleviated, the distortion of the solder joint portion, the substrate Warpage and internal cracks can be reduced. Even if the temperature around the solar battery cell 1 is repeatedly changed, since the connection portion 21 has a low elastic modulus, stress due to thermal expansion and contraction can be relieved. Generation | occurrence | production of a crack etc. can be prevented.

  The main component of the intermediate layer 26 is, for example, gold, silver, aluminum or the like. In particular, aluminum is preferable because it has a low elastic modulus and high conductivity, and is inexpensive.

  Since the copper of the surface layers 25 and 27 has good solder connectivity, it is suitable for soldering the connecting portion 21 to the surface electrode 16 or the back electrode 17. Moreover, since the surface layers 25 and 27 comprise the surface and the back surface of the connection part 21, the front-end | tip connects to the surface electrode 16 of the adjacent photovoltaic cell 1 in the state which connected the coating | coated part 22 to the board | substrate back surface 13. When doing so, it is not necessary to twist 180 degrees. That is, when the structure of the connection part 21 is two layers and only one surface is copper, when connecting the back surface electrode 17 of the board | substrate 11 and the surface electrode 16 of the adjacent photovoltaic cell 1, it is connected. Although it is necessary to invert the part by 180 degrees, it is not necessary to invert such a part.

  The thickness of the connection part 21 is 20 μm to 300 μm. If the thickness of the connecting portion 21 is 20 μm or less, the connecting portion 21 is liable to be broken, the production yield is lowered, and the electrical resistivity is increased. On the other hand, when the thickness of the connecting portion 21 is 300 μm or more, the thermal expansion becomes large. Therefore, a large difference in the thermal expansion between the substrate 11 and the connecting portion 21 occurs, and the substrate is cracked, chipped, or cracked. This is not preferable.

  The covering portion 22 is attached to the main body portion 21a of the connecting portion 21 so as to cover the entire back surface 13 of the substrate. Therefore, since the entire back surface 13 of the substrate is covered with copper having good conductivity, even if the substrate 11 is broken, the light output at the broken portion of the substrate can be collected.

<Embodiment 2>
A second embodiment of the present invention will be described with reference to FIG.

  FIG. 8 is a perspective view of the solar battery cell in the second embodiment viewed from the back side of the substrate.

  In the solar cell according to the present embodiment, a reinforcing member 81 made of a resin is attached to the back surface 13 of the solar cell 1 according to the first embodiment (see FIGS. 1 and 2) so as to cover the covering portion 22. It becomes the composition. The size of the reinforcing member 81 is to cover the back surface 13 of the substrate.

  With this configuration, the substrate 11 is reinforced, so that the solar cell can be prevented from cracking.

<Embodiment 3>
Next, the manufacturing method of the photovoltaic cell concerning this invention is demonstrated with reference to FIG.2 and FIG.5.

  First, a semiconductor substrate 11 made of a P-type silicon wafer to which a P-type conductivity type impurity is added is prepared. On the surface of the substrate 11, phosphorus or the like is diffused to form an N-type semiconductor layer 31, and a PN junction 39 is formed.

  Next, an uneven layer 32 for promoting the absorption of sunlight is formed on the surface of the N-type semiconductor layer 31.

The concavo-convex layer 32 is formed by performing dry etching on the N-type semiconductor layer 31 using a chlorine gas such as chlorine trifluoride gas (CClF ₃ ). Or you may form the uneven | corrugated layer 32 by performing wet etching using aqueous alkali solution, such as sodium hydroxide aqueous solution (NaOH).

  Next, an antireflection film 33 for preventing the reflection of sunlight is formed on the surface of the uneven layer 32.

  The antireflection film 33 is, for example, a silicon nitride film, and can be formed by a plasma CVD method using a mixed gas of silane and ammonia as a raw material. Alternatively, a titanium oxide film may be formed by a normal pressure CVD method using titanic acid alkoxide as a raw material.

An aluminum metal paste is printed on the back surface of the substrate 11 on which the antireflection film 33 is formed, and baked at about 700 ° C. to form a P ⁺ type semiconductor layer 34.

  Next, the front electrode 16 and the back electrode 17 are formed.

  The surface electrode 16 is formed by pattern printing of an Ag paste on the concavo-convex layer 32 and firing at about 200 to 300 ° C.

The back electrode 17 is formed by pattern-printing Ag paste on a part of the P ⁺ -type semiconductor layer 34 and baking at about 200 to 300 ° C.

  Next, an aluminum paste containing a resin component is printed and applied around the back electrode 17 on the back surface 13 of the substrate, and baked to form an aluminum layer. This step is a step for enhancing the adhesion between the heat-sensitive adhesive 51 and the substrate back surface 13, and may be omitted if sufficient adhesion between the heat-sensitive adhesive 51 and the substrate back surface 13 is ensured. Good.

  Next, solder layers 46 and 47 are formed on the front electrode 16 and the back electrode 17. The solder layers 46 and 47 are formed by immersing the substrate 11 in a solder bath and welding the solder to the portion where the Ag paste is applied.

  Next, the heat-sensitive adhesive 51 is applied to a region around the contact region 23 (region excluding the contact region 23 from the covering portion 22 and the main body portion 21a). Here, a solder layer may be formed in the contact region 23. With this configuration, the solder layer is formed in both the back electrode and the contact area of the connection portion that contacts the back electrode, so that the solder connection is more reliable.

  The covering portion 22 is affixed to the substrate back surface 13 so that the contact region 23 contacts the back electrode 17. At this time, the connecting portion 21 is led out of the substrate on the substrate back surface 13. The tip of the connection portion 21 is disposed on the surface electrode 16 formed on the substrate surface 12 of the adjacent solar battery cell 1.

  Note that when a solder layer is formed in the contact region 23, it is not necessary to form a solder layer on the back electrode 17. Further, when a solder layer is formed on the back electrode 17, it is not necessary to form the solder layer in the contact region 23 of the covering portion 22. That is, if the solder layer is formed at least on either the back electrode 17 or the contact region 23 that contacts the back electrode 17, the back electrode 17 and the covering portion 22 can be solder-connected.

  Further, the heat sensitive adhesive 51 is not applied to the area around the contact area 23 (the area excluding the contact area 23 from the covering part 22 and the main body part 21 a), and the heat is applied to the substrate back surface 13 around the back electrode 17. The adhesive 51 may be applied. That is, it is sufficient that the heat-sensitive adhesive 51 is applied to at least the periphery of the contact area 23 or the substrate back surface 13 around the back electrode 17.

  Next, the back surface electrode 17 and the contact region 23 are solder-bonded by heating at 200 ° C. to 300 ° C., and the substrate back surface 13 and the covering portion 22 are bonded to each other with a heat sensitive adhesive. Both of these steps may be performed simultaneously.

<Embodiment 4>
Next, the solar cell module according to the present invention will be described with reference to FIGS.

  FIG. 9 is a layout view in which solar cells are arranged in a matrix in the fourth embodiment according to the present invention.

  The solar cells 1 are arranged in a matrix form in a plurality of rows and columns on a mounting table 91 that also serves as a heating table. The solar cells 1 are connected to each other by a connecting portion 21 with a solder paste and a heat sensitive adhesive. Here, all the photovoltaic cells 1 are connected in series. Note that several solar cells 1 may be connected in series, and the solar cells 1 connected in series may be connected in parallel.

  Next, the structure 61 in the form of a matrix on the mounting table 91 is heated to a temperature at which the solder melts and the adhesive force of the heat-sensitive adhesive 51 is enhanced to form a solder joint, and at the same time the back surface of the substrate 13 and the covering portion 22 are bonded. Thereby, since solder joining and adhesion of the heat-sensitive adhesive 51 can be performed at the same time, production efficiency is improved. In addition, since solder bonding at a plurality of locations and adhesion of a heat-sensitive adhesive at a plurality of locations are performed at the same time, the heat history of solder bonding at a plurality of locations and the heat history of adhesion at a plurality of locations are made uniform, respectively. Module quality is stabilized.

  FIG. 10 (A) is a schematic view showing a method for assembling a solar cell module according to Embodiment 4 of the present invention, and FIG. 10 (B) is an assembly diagram for attaching an aluminum frame to a laminate of solar cell modules. is there.

  The structure 61 in which the solar cells 1 are connected in a matrix form has a filler (ethylene / vinyl acetate copolymer film: hereinafter referred to as EVA film) 71 formed on the light receiving portion 14 side in the form of a thin flat plate of transparent resin. A thin tempered glass 72 is laminated on the back side, and a weather-resistant back film (polyethylene terephthalate: hereinafter referred to as PET film) 73 is laminated on the back side through an EVA film 71 and heated and bonded.

  The laminated body 75 in which the thin plate tempered glass 72 and the PET film 73 are laminated has an aluminum frame 76 attached to the periphery. Thereby, a solar cell module having sufficient strength is completed.

(A) is the perspective view which looked at the photovoltaic cell in Embodiment 1 which concerns on this invention from the board | substrate surface side, (B) is the perspective view which looked at the photovoltaic cell in Embodiment 1 which concerns on this invention from the board | substrate back surface side. FIG. It is sectional drawing along arrow AA of the photovoltaic cell shown to FIG. 1 (A). (A) is a bottom view which shows the back surface pattern of the board | substrate in Embodiment 1 which concerns on this invention, (B) is a bottom view which shows the other back surface pattern of the board | substrate in Embodiment 1 which concerns on this invention. is there. It is a perspective view of the connection part in Embodiment 1 which concerns on this invention. It is explanatory drawing explaining adhesion | attachment with the board | substrate back surface and connection part in Embodiment 1 which concerns on this invention. It is a perspective view of the connection part in which the level | step-difference part in Embodiment 1 which concerns on this invention was provided. FIG. 5 is a cross-sectional view taken along arrows BB of the connection portion illustrated in FIG. 4. It is the perspective view which looked at the photovoltaic cell in Embodiment 2 which concerns on this invention from the substrate back surface. It is the layout which arrange | positioned the photovoltaic cell in the matrix form in Embodiment 4 which concerns on this invention. (A) is the schematic which shows the assembly method of the solar cell module in Embodiment 4 which concerns on this invention, (B) is an assembly drawing which attaches an aluminum frame to the laminated body of a solar cell module. (A) is a perspective view of the conventional photovoltaic cell, (B) is a side view of the conventional photovoltaic cell. It is explanatory drawing explaining the curvature of the board | substrate in the area | region where the back surface electrode of the conventional photovoltaic cell and the connection part joined.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solar cell 11 Substrate 12 Substrate surface 13 Substrate back surface 14 Light receiving part 16 Front surface electrode 17 Back surface electrode 21 Connection part 22 Covering part 23 Contact area 25, 27 Surface layer 26 Intermediate layer 29 Step 46, 47 Solder layer 81 Reinforcement member

Claims (8)

In a solar battery cell comprising a light receiving portion formed on the substrate surface, a surface electrode connected to the light receiving portion and formed on the substrate surface, and a back electrode formed on the back surface of the substrate,
A connecting portion connected to the back electrode and led out of the substrate from the back of the substrate;
The connecting portion is a metal foil provided with an extended covering portion covering the back surface of the substrate, and sandwiching an intermediate layer mainly composed of a metal having a smaller elastic coefficient than copper between two surface layers mainly composed of copper. A solar battery cell characterized by being as follows.   The solar cell according to claim 1, wherein the intermediate layer contains aluminum as a main component.   3. The solar cell according to claim 1, wherein a peripheral edge of the covering portion is arranged inside a peripheral edge of the back surface of the substrate.   The solar cell according to any one of claims 1 to 3, wherein a plurality of the back electrodes are formed discretely.   The solar cell according to any one of claims 1 to 4, wherein the connection portion has a step portion in a portion led out of the substrate.   The solar cell according to any one of claims 1 to 5, wherein the back surface of the substrate is covered with a reinforcing member made of resin so as to cover the covering portion.   The solar cell module formed by connecting a plurality of solar cells, wherein the solar cell is the solar cell according to any one of claims 1 to 6. A light receiving portion formed on the substrate surface, a surface electrode connected to the light receiving portion and formed on the substrate surface, a back electrode formed on the back surface of the substrate, and a contact region connected to the back electrode, the back surface of the substrate A method for manufacturing a solar cell module in which a plurality of solar cells each having a connection portion having an extension portion led out from is connected,
The connection part is a metal foil sandwiching an intermediate layer mainly composed of a metal having a smaller elastic coefficient than copper between two surface layers mainly composed of copper,
Forming a solder layer on each surface of the front electrode and the back electrode;
After contacting the contact area of the connection portion to the back electrode, and contacting the extension portion to the surface electrode of the adjacent solar battery cell,
A method of manufacturing a solar cell module, comprising heating and soldering the contact area and the back electrode, and the extension and the front electrode.

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