JP2007103536A - Solar battery module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar battery module in which optical loss and resistance loss due to a connection member can be reduced, and a manufacturing cost can be reduced and power generation efficiency can be improved. <P>SOLUTION: The solar battery module has front surface side connection tabs 2 which are formed so that the front surfaces of two adjacent solar cells 1, 1a are electrically connected. The two solar cells 1, 1a connected by the tabs 2 form one pair. Rear side connection tabs 3 are each formed so as to electrically connect the rear surfaces of a solar cells 1 of each pair to the rear surfaces of a solar cells 1a of another pair. The number of tabs 2 is smaller than the number of tabs 3. The center position of a width direction of each the tabs 2 is different from the center position of a width direction of each of the tabs 3. Each of the tab 2 has a shape different from that of each of the tabs 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solar cell module including a plurality of solar cells.

  Generally, a solar cell module is comprised by connecting a some solar cell in series (for example, refer patent documents 1-7).

  FIGS. 21A and 21B are a schematic cross-sectional view and a schematic side view showing the configuration of a conventional solar cell module.

  The solar cell module shown in FIG. 21 includes a plurality of solar cells 101 arranged so as to be adjacent to each other.

  A collector electrode is provided on a main light incident side surface (hereinafter referred to as a front surface) and a surface opposite to the front surface (hereinafter referred to as a back surface) of each solar cell 101. The collector electrode is composed of a plurality of thin finger electrode portions for collecting optical carriers generated by light incidence and a relatively thick bus bar electrode portion for taking out the collected optical carriers to the outside. Such a collector electrode is formed, for example, by screen-printing silver paste on the front and back surfaces.

  A connection tab 102 made of solder-coated copper foil or the like is bonded to the bus bar electrode portion on the surface of each solar cell 101, and the connection tab 102 is bonded to a bus bar electrode portion on the back surface of another adjacent solar cell 101. The connection tab 102 on the front surface and the connection tab 102 on the back surface of each solar cell 101 are provided at positions facing each other. In this way, a plurality of solar cells 101 are connected in series.

A translucent member 105 is disposed on the front surface side of the plurality of solar cells 101, a back surface member 106 is disposed on the back surface side of the plurality of solar cells 101, and the transparent member 105 is transparent between the translucent member 105 and the back surface member 106. A photo-resin 104 is filled.
JP-A-11-354822 JP 2000-164910 A JP 2001-237448 A JP 2002-26361 A JP 2002-1111024 A JP 2004-119687 A JP 2004-179260 A

  As described above, in the solar cell module, in order to connect a plurality of solar cells, one end of the connection tab on the front surface side of each solar cell is joined to the connection tab on the back surface side of the other solar cell adjacent to one side. The

  When the area of such a connection tab is large, the incidence of light on the solar cell is hindered, and the optical loss increases. On the other hand, when the area of the connection tab is small, the resistance loss at the connection tab increases, and the output of the solar cell module decreases.

  Moreover, the manufacturing process for connecting the back surface side of the other solar cell which adjoins the connection tab of the surface side of each solar cell to a connection tab is needed, and manufacturing cost becomes high. Furthermore, a space for a connection structure is required between the plurality of solar cells, and it becomes difficult to dispose the plurality of solar cells close to each other. As a result, improvement in power generation efficiency of the solar cell module is hindered.

  The objective of this invention is providing the solar cell module which can reduce the optical loss and resistance loss by a connection member, and can reduce manufacturing cost and the improvement of electric power generation efficiency.

  (1) A solar cell module according to the present invention is joined to a plurality of solar cells each having a first electrode and a second electrode on a first surface and a second surface, and a first electrode on the first surface of each solar cell. One or more first connection members in the form of strips and one or more second connection members in the form of strips joined to the second electrode on the second surface of each solar cell. 1 connection member is formed to be continuous, and the second connection members of a plurality of adjacent solar cells are formed to be continuous, and the shape of each first connection member of each solar cell and each second connection member The shape is different.

  In the solar cell module according to the present invention, the plurality of solar cells have the first electrode and the second electrode on the first surface and the second surface, respectively. One or more strip-shaped first connection members are joined to the first electrode on the first surface of each solar cell, and one or more strip-like second connection members are joined to the second electrode on the second surface of each solar cell. Has been.

  Here, the first connection members of the plurality of adjacent solar cells are formed to be continuous with each other, and the second connection members of the plurality of adjacent solar cells are formed to be continuous with each other. That is, a 1st connection member is arrange | positioned on the 1st surface of several adjacent solar cells, and a 2nd connection member is arrange | positioned on the 2nd surface of several adjacent solar cells. Thereby, since it is not necessary to connect the first connection member and the second connection member between the plurality of adjacent solar cells, the connection structure between the plurality of adjacent solar cells is simplified, and the manufacturing process is simplified. Is done. As a result, the manufacturing cost is reduced. Moreover, the space | interval between several adjacent solar cells can be made small. Thereby, the power generation efficiency of the solar cell module can be improved.

  Moreover, the shape of each 1st connection member of each solar cell differs from the shape of each 2nd connection member. Thereby, the first connecting member can be formed in a shape with a small optical loss. Further, the second connecting member can be formed in a shape with a small resistance loss. Therefore, the power generation efficiency and output of the solar cell module can be improved.

  (2) The maximum width of each first connection member of each solar cell may be smaller than the maximum width of each second connection member.

  In this case, since the maximum width of the first connecting member is smaller than the maximum width of the second connecting member, the optical loss due to the first connecting member can be reduced. As a result, the power generation efficiency of the solar cell module is further improved. Moreover, since the maximum width of the second connecting member is larger than the maximum width of the first connecting member, the electrical resistance of the second connecting member can be reduced. Thereby, the resistance loss by the 2nd connection member can be reduced. As a result, a decrease in the output of the solar cell module is sufficiently prevented.

  (3) The maximum thickness of each first connection member of each solar cell may be greater than the maximum thickness of each second connection member.

  In this case, the electrical resistance of the first connecting member can be reduced without increasing the maximum width of the first connecting member. Thereby, it is possible to further reduce optical loss and resistance loss due to the first connection member.

  (4) Each first connection member of each solar cell may have a substantially circular cross section, and each second connection member may have a flat cross section.

  In this case, the electrical resistance of the first connecting member can be reduced without increasing the maximum width of the first connecting member. Moreover, since the 1st connection member has a cylindrical outer peripheral surface, incident light is scattered in various directions and a part of the scattered light enters the first surface of the solar cell. Thereby, the optical loss and the resistance loss due to the first connection member can be sufficiently reduced. Moreover, the electrical resistance of the second connecting member can be sufficiently reduced. Thereby, the resistance loss due to the second connecting member can be sufficiently reduced.

  (5) The first electrode and the second electrode are metal electrodes partially formed on the first surface and the second surface, respectively, and the center position in the width direction of at least a part of the first connection member of each solar cell. And the center position in the width direction of the second connecting member may be different.

  In this case, when joining the second connection member to the plurality of solar cells after joining the first connection member to the plurality of solar cells, the heat at the time of joining the second connection member is applied to at least some of the first connection members. It becomes difficult to transmit. Thereby, it is prevented that the joint strength of the first connection member is lowered when the second connection member is joined.

  Therefore, the joining of the first connection member to the plurality of solar cells and the joining of the second connection member to the plurality of solar cells are performed in separate steps, and at the time of joining the first connection member and the joining of the second connection member. Thus, it is possible to set the processing conditions such as the heating temperature and the heating time more optimally.

  Moreover, even when joining the 1st connection member and 2nd connection member to a solar cell simultaneously, it becomes difficult to transmit heat between at least one part of 1st connection member and 2nd connection member. Accordingly, it is possible to set the processing conditions at the time of joining the first connecting member and the second connecting member more optimally.

  As a result, it is possible to improve the bonding strength between the first connecting member and the second connecting member, and the range of selection of the manufacturing process is expanded.

  It is preferable that the center position in the width direction of each first connection member of each solar cell is different from the center position in the width direction of each second connection member.

  In this case, it becomes difficult for heat to be transmitted between the first connecting member and the second connecting member when the first connecting member and / or the second connecting member are joined. Thereby, it is possible to further improve the bonding strength between the first connection member and the second connection member.

  (6) The first electrode and the second electrode are metal electrodes partially formed on the first surface and the second surface, respectively, and the number of first connection members and the number of second connection members of each solar cell May be different. In this case, the center position in the width direction of at least some of the first connection members of each solar cell is different from the center position in the width direction of all the second connection members, or at least part of the second connection of each solar cell. The center positions in the width direction of the members are different from the center positions in the width direction of all the first connecting members.

  Here, when joining the 2nd connection member to a plurality of solar cells after joining the 1st connection member to a plurality of solar cells, it becomes difficult to transmit the heat at the time of joining of the 2nd connection member to the 1st connection member. . Thereby, it is prevented that the joint strength of the first connection member is lowered when the second connection member is joined. Or when joining the 1st connection member to a plurality of solar cells after joining the 2nd connection member to a plurality of solar cells, it becomes difficult to transmit the heat at the time of joining of the 1st connection member to the 2nd connection member. Thereby, it is prevented that the joint strength of the second connection member is lowered when the first connection member is joined.

  Therefore, the joining of the first connection member to the plurality of solar cells and the joining of the second connection member to the plurality of solar cells are performed in separate steps, and at the time of joining the first connection member and the joining of the second connection member. Thus, it is possible to independently and optimally set the processing conditions such as the heating temperature and the heating time.

  Moreover, even when joining the 1st connection member and 2nd connection member to a solar cell simultaneously, it becomes difficult to transmit heat between at least one part of 1st connection member and 2nd connection member. Accordingly, it is possible to set the processing conditions at the time of joining the first connecting member and the second connecting member more optimally.

  As a result, the bonding strength of the first connection member and / or the second connection member can be improved, and the range of selection of the manufacturing process is expanded.

  (7) The plurality of solar cells includes a plurality of sets constituted by adjacent first and second solar cells, and the first electrode on the first surface of each first solar cell has the first polarity. The second electrode on the second surface of each first solar cell has a second polarity, the first electrode on the first surface of each second solar cell has a second polarity, 2nd electrode of the 2nd surface of 2 solar cells has the 1st polarity, and the 1st connection member of the 1st solar cell of each set, and the 1st connection member of the 2nd solar cell of the set concerned Formed so that the second connection member of the first solar cell of each set and the second connection member of the second solar cell of the other set adjacent to one side are continuous, The second connection member of the second solar cell in the set and the second connection member of the first solar cell in another set adjacent to the other side may be formed to be continuous.

  In this case, each set is composed of adjacent first and second solar cells. In each set, the first electrode of the first polarity of the first solar cell and the first electrode of the second polarity of the second solar cell are electrically connected by the first connection member. The second polarity second electrode of the first solar cell in each set and the second polarity second electrode of the second solar cell in the other set adjacent to one side are formed by the second connection member. Electrically connected. Furthermore, the second polarity second electrode of the second solar cell in each set and the second polarity second electrode of the first solar cell in the other set adjacent to the other side are provided by the second connection member. Electrically connected. In this way, the plurality of first and second solar cells arranged alternately are electrically connected in series with a simple structure.

  (8) The plurality of solar cells includes a plurality of sets each including a plurality of solar cells adjacent to each other, and the first electrode on the first surface of each solar cell has a first polarity. The second electrode of the second surface has the second polarity, and is formed such that the first connection members of the plurality of solar cells in each set are continuous, and the second connection members of the plurality of solar cells in each set are continuous. The first connection member of each set may be connected to another set of second connection members adjacent to each other.

  In this case, each set is composed of a plurality of solar cells that are sequentially adjacent. In each set, the first electrodes having the first polarity of the plurality of solar cells are electrically connected by the first connection member. Moreover, the 2nd polarity 2nd electrode of a several solar cell is electrically connected by the 2nd connection member in each group. Thereby, a plurality of solar cells in each set are electrically connected in parallel.

  In addition, each set of first connection members is connected to another set of adjacent second connection members. Thereby, a plurality of sets are electrically connected in series. In this way, a plurality of solar cells are connected in parallel and in series with a simple structure.

  (9) The plurality of solar cells alternately include a first set composed of a plurality of first solar cells sequentially adjacent to each other and a second set composed of a plurality of second solar cells sequentially adjacent to each other, The first electrode on the first surface of each first solar cell has a first polarity, the second electrode on the second surface of each first solar cell has a second polarity, and each second The first electrode on the first surface of the solar cell has a second polarity, the second electrode on the second surface of each second solar cell has a first polarity, and each of the first set of the plurality of second electrodes The first connection member of one solar cell and the first connection members of a second set of second solar cells adjacent to one side are formed to be continuous, and the plurality of first sets of each first set. The second connection member of the solar cell and the second connection member of the second set of second solar cells adjacent to the other side may be formed to be continuous.

  In this case, the first set is configured by a plurality of first solar cells that are sequentially adjacent, and the second set is configured by a plurality of second solar cells that are sequentially adjacent. The first polarity first electrodes of the plurality of first solar cells in each first set and the second polarity first electrodes of the plurality of second solar cells in the second set adjacent to one side are first. It is electrically connected by one connecting member. In addition, the second electrode of the second polarity of the plurality of first solar cells in each first set and the second electrode of the first polarity of the plurality of second solar cells in the second set adjacent to the other side Are electrically connected by the second connecting member. In this way, each first set of the plurality of first solar cells is electrically connected in parallel, each of the second set of the plurality of second solar cells is electrically connected in parallel, with a simple structure, One set and the second set are electrically connected in series.

  According to the present invention, it is not necessary to connect the first connection member and the second connection member between a plurality of adjacent solar cells, so that the connection structure between the plurality of adjacent solar cells is simplified, and the manufacturing process is performed. Is simplified. As a result, the manufacturing cost is reduced. Moreover, the space | interval between several adjacent solar cells can be made small. Thereby, the power generation efficiency of the solar cell module can be improved.

  Moreover, the shape of each 1st connection member of each solar cell differs from the shape of each 2nd connection member. Thereby, the first connecting member can be formed in a shape with a small optical loss. Further, the second connecting member can be formed in a shape with a small resistance loss. Therefore, the power generation efficiency and output of the solar cell module can be improved.

  Embodiments of the present invention will be described below with reference to the drawings.

(1) First Embodiment (a) Overall Configuration of Solar Cell Module FIG. 1 is a schematic plan view of a solar cell module according to a first embodiment of the present invention. FIGS. 2A and 2B are a schematic plan view and a schematic side view of a part of the solar cell module according to the first embodiment, respectively. 3 is a cross-sectional view taken along the line CC of FIG.

  In FIG. 1, two orthogonal directions indicated by arrows X and Y are referred to as a column direction and a row direction, respectively.

  The solar cell module shown in FIG. 1 includes two types of solar cells 1 and 1a arranged in a matrix in the column direction and the row direction.

  The main light incident surface (main light receiving surface) of each solar cell 1, 1 a is called a front surface, and the surface opposite to the front surface is called a back surface.

  In this Embodiment, the surface of the solar cell 1 is a positive electrode, and a back surface is a negative electrode. Moreover, the surface of the solar cell 1a is a negative electrode, and a back surface is a positive electrode.

  In each row, the solar cells 1 and the solar cells 1a are alternately arranged. The plurality of solar cells 1, 1 a arranged in each row are electrically connected in series by a plurality of front side connection tabs 2 and a plurality of back side connection tabs 3 described later.

  The back side connection tabs 3 of the solar cells 1 on one end side of the first row are connected to each other by the end connection tab 2a. A power cable 2e is connected to the end connection tab 2a.

  The back side connection tab 3 of the solar cell 1 on the other end side of the first row is connected to the back side connection tab 3 of the solar cell 1 on the other end side of the second row by the end connection tab 2b. Yes. The back surface side connection tab 3 of the solar cell 1a on the one end side of the second row is connected to the back surface side connection tab 3 of the solar cell 1 on the one end side of the third row by the end connection tab 2c.

  Similarly, the back side connection tab 3 of the solar cell 1a on the other end side of the odd-numbered row is connected to the back side connection tab 3 of the solar cell 1 on the other end side of the next even-numbered row by the end connection tab 2b. It is connected to the. The back surface side connection tab 3 of the solar cell 1a on the one end side of the even-numbered row is connected to the back surface side connection tab 3 of the solar cell 1 on the one end side of the next odd-numbered row by the end connection tab 2c.

  The back surface side connection tabs 3 of the solar cells 1a on one end side of the last row are connected to each other by the end connection tab 2d. A power cable 2f is connected to the end connection tab 2d.

  In this way, the plurality of solar cells 1 and 1a arranged in a plurality of rows are electrically connected in series between the power cable 2e and the power cable 2f.

  Note that a terminal box having a diode is arranged at one end of the solar cell module as a means for preventing reverse voltage from being applied when light incident on some solar cells 1 is blocked by the influence of shadows. The Here, the terminal box is not shown in order to simplify the drawing.

  As shown in FIG. 2A, two surface-side connection tabs 2 are formed so as to electrically connect the surfaces of two adjacent solar cells 1 and 1a. The two surface-side connection tabs 2 extend in parallel with each other along the column direction at positions approximately in the center of the regions obtained by dividing the entire surface of the solar cells 1 and 1a into approximately two equal parts. Two solar cells 1 and 1a connected to each other by the surface side connection tab 2 constitute one set.

  Three back surface side connection tabs 3 are formed so as to electrically connect the back surface of each set of solar cells 1 and the back surface of another set of adjacent solar cells 1a. The three back-side connection tabs 3 extend in parallel to each other along the column direction at substantially the center positions of the regions obtained by dividing the entire back surface into approximately three equal parts.

  Thus, the number of the front surface side connection tabs 2 is smaller than the number of the back surface side connection tabs 3. The center position in the width direction of the front surface side connection tab 2 is different from the center position in the width direction of the back surface side connection tab 3.

  As shown in FIG.2 (b), the surface side connection tab 2 is joined on the surface of the adjacent solar cells 1 and 1a within the same group, and the back surface side connection tab 3 is a solar cell adjacent between different groups. It is joined on the back surface of 1,1a. Thereby, the positive electrode on the surface of each solar cell 1 is electrically connected to the negative electrode on the surface of the solar cell 1a adjacent to one side, and the negative electrode on the back surface of each solar cell 1 is connected to the back side of the solar cell 1a adjacent to the other side. Is electrically connected to the positive electrode. Thereby, the plurality of solar cells 1 and 1a in each row are electrically connected in series.

  The plurality of solar cells 1, 1 a are sealed with a sealing material 4 made of a light-transmitting resin, a light-transmitting surface member 5 is provided on the front surface side of the sealing material 4, and the back surface side of the sealing material 4 A back surface member 6 is provided on the surface. As the sealing material 4, EVA (ethylene vinyl acetate) or the like can be used. As the surface member 5, a translucent material such as transparent glass or a transparent film can be used. The back member 6 has a structure in which, for example, aluminum is sandwiched between vinyl fluoride films. A frame body 7 in FIG. 1 is mounted around the front surface member 5, the sealing material 4, and the back surface member 6.

  As shown in FIG. 3, the surface-side connection tab 2 is made of a metal wire having a circular cross section. As the surface side connection tab 2, for example, a copper wire is used. The surface of the copper wire is plated with solder that does not contain lead. The diameter of the surface side connection tab 2 is, for example, 0.5 mm.

  The back surface side connection tab 3 is made of a striped metal foil. For example, a copper foil is used as the back side connection tab 3. The surface of the copper foil is subjected to solder plating not containing lead. The width of the back side connection tab 3 is 2 mm, for example, and the thickness is 0.1 mm.

  Thus, in this Embodiment, the surface side connection tab 2 and the back surface side connection tab 3 have a different shape.

  In the solar cell module of the present embodiment, light is incident mainly from the front surface side of the solar cells 1, 1 a through the surface member 5, but the reflected light from the back member 6 is also incident from the back surface side of the solar cells 1, 1 a. To do.

(B) Electrode Structure of Solar Cell FIG. 4 is a plan view of the front side of one solar cell 1, and FIG. 5 is a plan view of the back side of one solar cell 1.

  As shown in FIG. 4, the solar cell 1 includes an n-type single crystal silicon wafer 11 having a substantially square shape. A surface electrode 12 made of a transparent conductive film such as ITO (indium tin oxide) is formed on the main surface side of the n-type single crystal silicon wafer 11 via an amorphous silicon film described later. On the surface electrode 12, two striped bus bar electrode portions 13p are formed in parallel to each other, and a plurality of striped finger electrode portions 14p are formed in parallel to each other so as to be orthogonal to the bus bar electrode portions 13p. . The bus bar electrode portion 13p and the finger electrode portion 14p constitute a collecting electrode 15p that functions as a positive electrode.

  As shown in FIG. 5, a back electrode 25 made of a transparent conductive film such as ITO is formed on the back side of an n-type single crystal silicon wafer 11 with an amorphous silicon film described later. On the back electrode 25, three striped bus bar electrode portions 13n are formed in parallel with each other, and a plurality of striped finger electrode portions 14n are formed in parallel with each other so as to be orthogonal to the bus bar electrode portions 13n. . The bus bar electrode portion 13n and the finger electrode portion 14n constitute a collector electrode 15n that functions as a negative electrode.

  The collector electrodes 15p and 15n are formed of a conductive paste containing conductive particles such as Ag (silver).

  6 is a plan view of the front side of one solar cell 1a, and FIG. 7 is a plan view of the back side of one solar cell 1a.

  As shown in FIG. 6, the solar cell 1a includes an n-type single crystal silicon wafer 11 having a substantially square shape. On the main surface side of the n-type single crystal silicon wafer 11, a surface electrode 12a made of a transparent conductive film such as ITO is formed through an amorphous silicon film described later. On the surface electrode 12a, two striped bus bar electrode portions 13n are formed in parallel to each other, and a plurality of striped finger electrode portions 14n are formed in parallel to each other so as to be orthogonal to the bus bar electrode portions 13n. . The bus bar electrode portion 13n and the finger electrode portion 14n constitute a collector electrode 15n that functions as a negative electrode.

  As shown in FIG. 7, a back electrode 25a made of a transparent conductive film such as ITO is formed on the back side of an n-type single crystal silicon wafer 11 with an amorphous silicon film described later. On the back electrode 25a, three striped bus bar electrode portions 13p are formed in parallel to each other, and a plurality of striped finger electrode portions 14p are formed in parallel to each other so as to be orthogonal to the bus bar electrode portions 13p. . The bus bar electrode portion 13p and the finger electrode portion 14p constitute a collecting electrode 15p that functions as a positive electrode.

  The collector electrodes 15n and 15p are formed of a conductive paste containing conductive particles such as Ag (silver).

  Thus, the collector electrode 15n on the surface side of the solar cell 1a has the same shape as the collector electrode 15p on the surface side of the solar cell 1, and the collector electrode 15p on the back surface side of the solar cell 1a is the back surface side of the solar cell 1. The collector electrode 15n has the same shape.

(C) Connection Tab Joining Method The front side connection tabs 2 of FIGS. 2 and 3 are arranged on the bus bar electrode part 13p of FIG. 4 and the bus bar electrode part 13n of FIG. In this state, the surface-side connection tab 2 is heated, so that the solder of the surface-side connection tab 2 is melted, and the surface-side connection tab 2 is joined onto the bus bar electrode portion 13p and the bus bar electrode portion 13n.

  2 and FIG. 3 are arranged on the bus bar electrode portion 13n in FIG. 5 and the bus bar electrode portion 13p in FIG. In this state, when the back surface side connection tab 3 is heated, the solder of the back surface side connection tab 3 is melted, and the back surface side connection tab 3 is joined onto the bus bar electrode portion 13n and the bus bar electrode portion 13p.

(D) Layer structure of solar cell FIG. 8 is a schematic cross-sectional view of the solar cell 1. As shown in FIG. 8, an i-type amorphous silicon film 21 and a p-type amorphous silicon film 22 are sequentially formed on the main surface of an n-type single crystal silicon wafer 11. The n-type single crystal silicon wafer 11, the i-type amorphous silicon film 21, and the p-type amorphous silicon film 22 form a photoelectric conversion layer, and the n-type single crystal silicon wafer 11 serves as a main power generation layer.

  A surface electrode 12 is formed on the p-type amorphous silicon film 22. As shown in FIG. 4, a collecting electrode 15 p including a plurality of bus bar electrode portions 13 p and a plurality of finger electrode portions 14 p is formed on the surface electrode 12.

  An i-type amorphous silicon film 23 and an n-type amorphous silicon film 24 are sequentially formed on the back surface of the n-type single crystal silicon wafer 11. A back electrode 25 made of a transparent conductive film such as ITO is formed on the n-type amorphous silicon film 24. As shown in FIG. 5, on the back electrode 25, a collecting electrode 15n including a plurality of bus bar electrode portions 13n and a plurality of finger electrode portions 14n is formed.

  The solar cell 1 of the present embodiment is a HIT in which an i-type amorphous silicon film 21 is provided between an n-type single crystal silicon wafer 11 and a p-type amorphous silicon film 22 in order to improve the pn junction characteristics. (Heterojunction with Intrinsic Thin-Layer) type structure and an i-type amorphous silicon film on the back surface of the n-type single crystal silicon wafer 11 in order to prevent carrier recombination on the back surface 23 and a BSF (Back Surface Field) structure in which an n-type amorphous silicon film 24 is provided.

  In the solar cell 1 of the present embodiment, light is mainly incident from the front electrode 12, but light is also incident from the back electrode 25. Carriers generated in the n-type single crystal silicon wafer 11 are diffused as a photocurrent to the front electrode 12 and the back electrode 25 and are collected by the collector electrodes 15p and 15n.

  FIG. 9 is a schematic cross-sectional view of the solar cell 1a. As shown in FIG. 9, an i-type amorphous silicon film 23 and an n-type amorphous silicon film 24 are sequentially formed on the main surface of the n-type single crystal silicon wafer 11. The n-type single crystal silicon wafer 11, the i-type amorphous silicon film 23, and the n-type amorphous silicon film 24 form a photoelectric conversion layer, and the n-type single crystal silicon wafer 11 becomes a main power generation layer.

  A surface electrode 12 a is formed on the n-type amorphous silicon film 24. As shown in FIG. 6, a collector electrode 15n including a plurality of bus bar electrode portions 13n and a plurality of finger electrode portions 14n is formed on the surface electrode 12a.

  An i-type amorphous silicon film 21 and a p-type amorphous silicon film 22 are sequentially formed on the back surface of the n-type single crystal silicon wafer 11. A back electrode 25 a made of a transparent conductive film such as ITO is formed on the p-type amorphous silicon film 22. As shown in FIG. 7, a collecting electrode 15p including a plurality of bus bar electrode portions 13p and a plurality of finger electrode portions 14p is formed on the back electrode 25a.

  In solar cell 1a of the present embodiment, light is mainly incident from surface electrode 12a, but light is also incident from back electrode 25a. Carriers generated in the n-type single crystal silicon wafer 11 are diffused to the front electrode 12a and the back electrode 25a as a photocurrent and collected by the collector electrodes 15n and 15p.

(E) Effects of the First Embodiment In the solar cell module of the present embodiment, the front surface side connection tab 2 is made of a metal wire having a circular cross section, and the back surface side connection tab 3 is made of a striped metal foil. . Thus, the front surface side connection tab 2 and the back surface side connection tab 3 have different shapes.

  In this case, the number of the front surface side connection tabs 2 is smaller than the number of the rear surface side connection tabs 3, and the diameter of the front surface side connection tabs 2 is smaller than the width of the rear surface side connection tabs 3. Moreover, since the surface side connection tab 2 has a cylindrical outer peripheral surface, incident light is scattered in various directions, and a part of the scattered light is incident from the surface side of the solar cells 1 and 1a. As a result, the optical loss due to the surface-side connection tab 2 can be reduced on the surface side that is the main light incident surface. As a result, the power generation efficiency of the solar cell module is improved.

  On the other hand, the number of the back-side connection tabs 3 is larger than the number of the front-side connection tabs 2 and the back-side connection tabs 3 have a large area, so that the electrical resistance is small. Moreover, since the surface side connection tab 2 has a circular cross section, the electrical resistance of the surface side connection tab 2 can be kept small. Thereby, the resistance loss in the surface side connection tab 2 and the back surface side connection tab 3 of a solar cell module can be reduced. As a result, a decrease in the output of the solar cell module is prevented.

  Moreover, the front surface side connection tab 2 extends on the surface of the adjacent solar cells 1, 1a in the same set, and the back surface side connection tab 3 extends on the back surface of the adjacent solar cells 1, 1a between different sets. Thereby, since it is not necessary to connect the front surface side connection tab 2 and the back surface side connection tab 3, an edge part connection tab becomes unnecessary. Therefore, the connection structure between the adjacent solar cells 1 and 1a is simplified, and the manufacturing process is simplified. As a result, the manufacturing cost is reduced. Moreover, the space | interval between adjacent solar cells 1 and 1a can be made small. As a result, the power generation efficiency of the solar cell module can be further improved.

  Furthermore, the number of front side connection tabs 2 is smaller than the number of back side connection tabs 3. Moreover, the center position of the width direction of the surface side connection tab 2 and the center position of the width direction of the back surface side connection tab 3 differ.

  Therefore, when joining the back surface side connection tab 3 to the plurality of solar cells 1, 1 a after joining the surface side connection tab 2 to the plurality of solar cells 1, 1 a, the heat at the time of joining the back surface side connection tab 3 is the surface It becomes difficult to transmit to the side connection tab 2. Thereby, it is prevented that the bonding strength of the front surface side connection tab 2 is lowered when the back surface side connection tab 3 is bonded. Alternatively, when the front-side connection tab 2 is joined to the plurality of solar cells 1, 1 a after the back-side connection tab 3 is joined to the plurality of solar cells 1, 1 a, the heat at the time of joining the front-side connection tab 2 is the back side It becomes difficult to transmit to the side connection tab 3. Thereby, it is prevented that the bonding strength of the back surface side connection tab 3 is lowered when the front surface side connection tab 2 is bonded.

  Therefore, joining of the front surface side connection tab 2 to the plurality of solar cells 1, 1 a and joining of the back surface side connection tab 3 to the plurality of solar cells 1, 1 a are performed in separate steps, and joining of the front surface side connection tab 2. The processing conditions such as the heating temperature and the heating time can be set independently and optimally at the time and when the back surface side connection tab 3 is joined.

  Further, even when the front-side connection tab 2 and the back-side connection tab 3 are simultaneously joined to the solar cells 1, 1 a, heat is hardly transmitted between the front-side connection tab 2 and the back-side connection tab 3. Therefore, it is possible to independently and optimally set the processing conditions at the time of joining the front surface side connection tab 2 and the back surface side connection tab 3.

  As can be seen from these results, the bonding strength of the front surface side connection tab 2 and the back surface side connection tab 3 can be improved, and the range of selection of the manufacturing process is expanded.

(F) Another Arrangement Example of Connection Tab FIG. 10 is a cross-sectional view showing another arrangement example of the front surface side connection tab 2 and the back surface side connection tab 3.

  As shown in FIG. 10, the two back side connection tabs 3 may be provided at positions where the two front side connection tabs 2 overlap. In this case, the center position P1 in the width direction of each front surface side connection tab 2 and the center position P2 in the width direction of each back surface side connection tab 3 are different.

  Thereby, the joining of the front surface side connection tab 2 to the plurality of solar cells 1, 1 a and the joining of the back surface side connection tab 3 to the plurality of solar cells 1, 1 a are performed in separate steps. The processing conditions such as the heating temperature and the heating time can be set independently and optimally at the time of bonding and at the time of bonding of the back surface side connection tab 3. As a result, it is possible to improve the bonding strength of the front surface side connection tab 2 and the back surface side connection tab 3.

(2) Second Embodiment (a) Overall Configuration of Solar Cell Module FIG. 11 is a schematic plan view of a solar cell module according to a second embodiment of the present invention. FIGS. 12A and 12B are a schematic plan view and a schematic side view of a part of the solar cell module according to the second embodiment, respectively. FIG. 13 is a cross-sectional view taken along the line DD of FIG.

  The solar cell module according to the second embodiment is different from the solar cell module according to the first embodiment in the following points.

  The solar cell module shown in FIG. 11 includes a plurality of solar cells 1 arranged in a matrix in the column direction and the row direction.

  In the present embodiment, a plurality of solar cells 1 arranged in each row are divided into a plurality of sets. Each set consists of two adjacent solar cells 1. The plurality of front surface side connection tabs 2 and the plurality of back surface side connection tabs 3 electrically connect each of the two solar cells 1 in parallel, and two adjacent groups are electrically connected in series.

  As shown to Fig.12 (a), the two surface side connection tabs 2 are formed so that the surface of the two adjacent solar cells 1 of each group may be electrically connected. The two surface-side connection tabs 2 extend in parallel with each other along the column direction at positions substantially in the center of the region obtained by dividing the entire surface of the solar cell 1 into two equal parts.

  Three back-side connection tabs 3 are formed so as to electrically connect the back surfaces of two adjacent solar cells 1 in each set. The three back-side connection tabs 3 extend in parallel to each other along the column direction at substantially the center positions of the regions obtained by dividing the entire back surface into approximately three equal parts.

  Thus, the number of the front surface side connection tabs 2 is smaller than that of the back surface side connection tabs 3. The center position in the width direction of the front surface side connection tab 2 is different from the center position in the width direction of the back surface side connection tab 3.

  As described above, the positive electrodes on the surfaces of the two adjacent solar cells 1 in each set are connected by the surface-side connection tab 2, and the negative electrodes on the back surfaces of the two adjacent solar cells 1 in each set are connected on the back side. Connected by tab 3. Thereby, two adjacent solar cells 1 of each set are electrically connected in parallel.

  One end of each of the three back side connection tabs 3 of each set is joined to an end connection tab 3 a extending in a direction orthogonal to the back side connection tab 3 on the back side of one solar cell 1.

  As shown in FIG. 12 (b), the front surface side connection tabs 2 of the solar cells 1 in each set are joined to the end connection tabs 3a on the back surface of the other set of solar cells 1 adjacent to one side in the same row. Has been. As a result, the positive electrode on the surface of each set of solar cells 1 is electrically connected to the negative electrode on the back surface of another adjacent set of solar cells 1.

  In this way, a set of two solar cells 1 electrically connected in parallel is electrically connected in series within each column.

  As shown in FIG. 13, the surface-side connection tab 2 is made of a metal wire having a circular cross section. As the surface side connection tab 2, for example, a copper wire is used. The surface of the copper wire is plated with solder that does not contain lead. The diameter of the surface side connection tab 2 is, for example, 0.7 mm.

  The back surface side connection tab 3 is made of a striped metal foil. For example, a copper foil is used as the back side connection tab 3. The surface of the copper foil is subjected to solder plating not containing lead. The width of the back side connection tab 3 is, for example, 4 mm, and the thickness is 0.1 mm.

  Thus, in this Embodiment, the surface side connection tab 2 and the back surface side connection tab 3 have a different shape.

  The end connection tab 3 a is made of a striped metal foil, like the back-side connection tab 3. For example, a copper foil is used as the end connection tab 3a. The surface of the copper foil is subjected to solder plating not containing lead. The width of the end connection tab 3a is 5 mm, for example, and the thickness is 0.1 mm.

  In the present embodiment, the end connection tab 3a is formed separately from the back surface side connection tab 3, and is joined to the back surface side connection tab 3 by soldering, but the end connection tab 3a is connected to the back surface side connection tab 3. And may be formed integrally. In that case, the back surface side connection tab 3 is formed in an E-shape.

  Further, the two front surface side connection tabs 2 of each solar cell 1, the three back surface side connection tabs 3 and the end portion connection tabs 3a of the solar cell 1 adjacent to one side may be integrally formed.

(B) Connection Tab Joining Method The front side connection tab 2 of FIGS. 12 and 13 is disposed on the bus bar electrode portion 13p of FIG. In this state, the front side connection tab 2 is heated, so that the solder of the front side connection tab 2 is melted, and the front side connection tab 2 is joined onto the bus bar electrode portion 13p.

  12 and FIG. 13 is disposed on the bus bar electrode portion 13n in FIG. 5, and the end connection tab 3a is disposed so as to be orthogonal to one end of the back surface connection tab 3. In this state, when the back surface side connection tab 3 and the end portion connection tab 3a are heated, the solder of the back surface side connection tab 3 and the end portion connection tab 3a is melted, and the back surface side connection tab 3 is formed on the bus bar electrode portion 13n. Are joined, and the end connection tab 3 a is joined so as to be orthogonal to one end of the back side connection tab 3.

  Furthermore, one end of the surface side connection tab 2 of one solar cell 1 of each set is disposed on the end connection tab 3a of one solar cell 1 of another adjacent group. In this state, the front side connection tab 2 is heated, whereby the solder of the front side connection tab 2 is melted and one end of the front side connection tab 2 is joined to the end connection tab 3a.

(C) Effect of Second Embodiment In the solar cell module of the present embodiment, the front surface side connection tab 2 is made of a metal wire having a circular cross section, and the back surface side connection tab 3 is made of a striped metal foil. . Thus, the front surface side connection tab 2 and the back surface side connection tab 3 have different shapes.

  In this case, the number of the front surface side connection tabs 2 is smaller than the number of the rear surface side connection tabs 3, and the diameter of the front surface side connection tabs 2 is smaller than the width of the rear surface side connection tabs 3. Moreover, since the surface side connection tab 2 has a cylindrical outer peripheral surface, incident light is scattered in various directions, and a part of the scattered light enters from the surface side of the solar cell 1. As a result, the optical loss due to the surface-side connection tab 2 can be reduced on the surface side that is the main light incident surface. As a result, the power generation efficiency of the solar cell module is improved.

  On the other hand, the number of the back-side connection tabs 3 is larger than the number of the front-side connection tabs 2 and the back-side connection tabs 3 have a large area, so that the electrical resistance is small. Moreover, since the surface side connection tab 2 has a circular cross section, the electrical resistance of the surface side connection tab 2 can be kept small. Thereby, the resistance loss in the surface side connection tab 2 and the back surface side connection tab 3 of a solar cell module can be reduced. As a result, a decrease in the output of the solar cell module is prevented.

  Moreover, the front surface side connection tab 2 extends on the surface of the adjacent solar cell 1 in the same set, and the back surface side connection tab 3 extends on the back surface of the adjacent solar cell 1 in the same set. Thereby, it is not necessary to connect the front surface side connection tab 2 and the back surface side connection tab 3 within the same group. Therefore, the connection structure between the adjacent solar cells 1 in the same set is simplified, and the manufacturing process is simplified. As a result, the manufacturing cost is reduced. Moreover, the space | interval between the adjacent solar cells 1 within the same group can be made small. As a result, the power generation efficiency of the solar cell module can be further improved.

  In addition, a plurality of solar cells 1 can be connected in parallel and in series with a simple structure.

  Furthermore, the number of front side connection tabs 2 is smaller than the number of back side connection tabs 3. Moreover, the center position of the width direction of the surface side connection tab 2 and the center position of the width direction of the back surface side connection tab 3 differ.

  Therefore, when joining the back surface side connection tab 3 to the plurality of solar cells 1 after joining the surface side connection tab 2 to the plurality of solar cells 1, the heat at the time of joining the back surface side connection tab 3 is the surface side connection tab 2. It becomes difficult to transmit to. Thereby, it is prevented that the bonding strength of the front surface side connection tab 2 is lowered when the back surface side connection tab 3 is bonded. Alternatively, when the front surface side connection tab 2 is bonded to the plurality of solar cells 1 after the back surface side connection tab 3 is bonded to the plurality of solar cells 1, the heat at the time of bonding of the front surface side connection tab 2 is the back surface side connection tab 3. It becomes difficult to transmit to. Thereby, it is prevented that the bonding strength of the back surface side connection tab 3 is lowered when the front surface side connection tab 2 is bonded.

  Therefore, the joining of the front surface side connection tabs 2 to the plurality of solar cells 1 and the joining of the back surface side connection tabs 3 to the plurality of solar cells 1 are performed in separate steps. The processing conditions such as the heating temperature and the heating time can be set independently and optimally when the connection tab 3 is joined.

  Further, even when the front surface side connection tab 2 and the back surface side connection tab 3 are joined to the solar cell 1 at the same time, heat is hardly transferred between the front surface side connection tab 2 and the back surface side connection tab 3. Therefore, it is possible to independently and optimally set the processing conditions at the time of joining the front surface side connection tab 2 and the back surface side connection tab 3.

  As can be seen from these results, the bonding strength of the front surface side connection tab 2 and the back surface side connection tab 3 can be improved, and the range of selection of the manufacturing process is expanded.

  Moreover, since the center position of the width direction of the surface side connection tab 2 and the center position of the width direction of the back surface side connection tab 3 differ, it is prevented that the surface side connection tab 2 and the back surface side connection tab 3 short-circuit. .

(D) Another Arrangement Example of Connection Tab FIG. 14 is a cross-sectional view showing another arrangement example of the front surface side connection tab 2 and the rear surface side connection tab 3.

  As shown in FIG. 14, the two back surface side connection tabs 3 may be provided at positions where the two front surface side connection tabs 2 overlap. In this case, the center position P1 in the width direction of each front surface side connection tab 2 and the center position P2 in the width direction of each back surface side connection tab 3 are different.

  Thereby, the joining of the front surface side connection tab 2 to the plurality of solar cells 1 and the joining of the back surface side connection tab 3 to the plurality of solar cells 1 are performed in separate steps. The processing conditions such as the heating temperature and the heating time can be set independently and optimally when the side connection tab 3 is joined. As a result, it is possible to improve the bonding strength of the front surface side connection tab 2 and the back surface side connection tab 3.

(3) Third Embodiment (a) Overall Configuration of Solar Cell Module FIG. 15 is a schematic plan view of a solar cell module according to a third embodiment of the present invention. FIGS. 16A and 16B are a schematic plan view and a schematic side view of a part of the solar cell module according to the third embodiment, respectively. The cross section taken along the line EE of FIG. 16A is the same as the cross section shown in FIG.

  The solar cell module according to the third embodiment is different from the solar cell module according to the first embodiment in the following points.

  The solar cell module shown in FIG. 15 includes two types of solar cells 1 and 1a arranged in a matrix in the column direction and the row direction.

  In this Embodiment, the surface of the solar cell 1 is a positive electrode, and a back surface is a negative electrode. Moreover, the surface of the solar cell 1a is a negative electrode, and a back surface is a positive electrode.

  In each row, a set of two solar cells 1 and a set of two solar cells 1a are alternately arranged. Hereinafter, a set of two solar cells 1 is called a first set, and a set of two solar cells 1a is called a second set.

  In the present embodiment, the first set of two solar cells 1 are electrically connected in parallel by the plurality of front surface side connection tabs 2 and the plurality of back surface side connection tabs 3, and the second set of two solar cells 1. Are electrically connected in parallel, and the adjacent first and second sets are electrically connected in series.

  The back side connection tabs 3 of the solar cells 1 on one end side of the first row are connected to each other by the end connection tab 2a. A power cable 2e is connected to the end connection tab 2a.

  The back side connection tab 3 of the solar cell 1a on the other end side of the first row is connected to the back side connection tab 3 of the solar cell 1 on the other end side of the second row by the end connection tab 2b. Yes. The back surface side connection tab 3 of the solar cell 1a on the one end side of the second row is connected to the back surface side connection tab 3 of the solar cell 1 on the one end side of the third row by the end connection tab 2c.

  Similarly, the back side connection tab 3 of the solar cell 1a on the other end side of the odd-numbered row is connected to the back side connection tab 3 of the solar cell 1 on the other end side of the next even-numbered row by the end connection tab 2b. It is connected to the. The back surface side connection tab 3 of the solar cell 1a on the one end side of the even-numbered row is connected to the back surface side connection tab 3 of the solar cell 1 on the one end side of the next odd-numbered row by the end connection tab 2c.

  The back surface side connection tabs 3 of the solar cells 1a on one end side of the last row are connected to each other by the end connection tab 2d. A power cable 2f is connected to the end connection tab 2d.

  As shown in FIG. 16 (a), two so as to electrically connect the surface of each of the first set of two solar cells 1 and the surface of the second set of two solar cells 1a adjacent to one side. The front surface side connection tab 2 is formed. The two surface-side connection tabs 2 extend in parallel with each other along the column direction at positions approximately in the center of the regions obtained by dividing the entire surface of the solar cells 1 and 1a into approximately two equal parts.

  Three back surface side connection tabs 3 are formed so as to electrically connect the back surface of each of the first set of two solar cells 1 and the back surface of the second set of two solar cells 1a adjacent to the other side. Yes. The three back-side connection tabs 3 extend in parallel to each other along the column direction at substantially the center positions of the regions obtained by dividing the entire back surface into approximately three equal parts.

  Thus, the number of the front surface side connection tabs 2 is smaller than the number of the back surface side connection tabs 3. The center position in the width direction of the front surface side connection tab 2 is different from the center position in the width direction of the back surface side connection tab 3.

  As shown in FIG. 16 (b), the front surface side connection tab 2 is bonded onto the surface of each first set of solar cells 1 and the second set of solar cells 1 a adjacent to one side, and the back surface side connection tab 3. Are joined on the back surface of each first set of solar cells 1 and the second set of solar cells 1a adjacent to the other side. Thereby, the positive electrodes on the surface of the two solar cells 1 in the first set are electrically connected to each other, and the negative electrodes on the back surface of the two solar cells 1 in the first set are electrically connected to each other. Further, the negative electrodes on the surface of the second set of two solar cells 1a are electrically connected to each other, and the positive electrodes on the back surface of the second set of two solar cells 1a are electrically connected to each other. Furthermore, the positive electrode on the surface of the first set of two solar cells 1 is electrically connected to the negative electrode on the surface of the second set of two solar cells 1a adjacent to one side, and the two solar cells 1 in the first set. Is electrically connected to the positive electrode on the back surface of the second set of two solar cells 1a adjacent to the other side.

  In this way, the first set of two solar cells 1 electrically connected in parallel and the second set of two solar cells 1a electrically connected in parallel are electrically connected in series within each row. The

  The surface side connection tab 2 is made of a metal wire having a circular cross section. As the surface side connection tab 2, for example, a copper wire is used. The surface of the copper wire is plated with solder that does not contain lead. The diameter of the surface side connection tab 2 is, for example, 0.7 mm.

  The back surface side connection tab 3 is made of a striped metal foil. For example, a copper foil is used as the back side connection tab 3. The surface of the copper foil is subjected to solder plating not containing lead. The width of the back side connection tab 3 is, for example, 4 mm, and the thickness is 0.1 mm.

  Thus, in this Embodiment, the surface side connection tab 2 and the back surface side connection tab 3 have a different shape.

  In addition, the electrode structure of the solar cell 1 is the same as the structure shown in FIG. 4 and FIG. The electrode structure of the solar cell 1a is the same as the structure shown in FIGS. The layer structure of the solar cell 1 is the same as the structure shown in FIG. The layer structure of the solar cell 1a is the same as the structure shown in FIG.

(B) Effects of Third Embodiment In the solar cell module of the present embodiment, the front surface side connection tab 2 is made of a metal wire having a circular cross section, and the back surface side connection tab 3 is made of a striped metal foil. . Thus, the front surface side connection tab 2 and the back surface side connection tab 3 have different shapes.

  In this case, the number of the front surface side connection tabs 2 is smaller than the number of the rear surface side connection tabs 3, and the diameter of the front surface side connection tabs 2 is smaller than the width of the rear surface side connection tabs 3. Moreover, since the surface side connection tab 2 has a cylindrical outer peripheral surface, incident light is scattered in various directions, and a part of the scattered light is incident from the surface side of the solar cells 1 and 1a. As a result, the optical loss due to the surface-side connection tab 2 can be reduced on the surface side that is the main light incident surface. As a result, the power generation efficiency of the solar cell module is improved.

  On the other hand, the number of the back-side connection tabs 3 is larger than the number of the front-side connection tabs 2 and the back-side connection tabs 3 have a large area, so that the electrical resistance is small. Moreover, since the surface side connection tab 2 has a circular cross section, the electrical resistance of the surface side connection tab 2 can be kept small. Thereby, the resistance loss in the surface side connection tab 2 and the back surface side connection tab 3 of a solar cell module can be reduced. As a result, a decrease in the output of the solar cell module is prevented.

  Moreover, the surface side connection tab 2 is extended on the surface of the solar cells 1 and 1a, and the back surface side connection tab 3 is extended on the back surface of the solar cells 1 and 1a. Thereby, since it is not necessary to connect the front surface side connection tab 2 and the back surface side connection tab 3, an edge part connection tab becomes unnecessary. Therefore, the connection structure between the adjacent solar cells 1, between the adjacent solar cells 1a and between the adjacent solar cells 1 and 1a is simplified, and the manufacturing process is simplified. As a result, the manufacturing cost is reduced. Moreover, the space | interval between the adjacent solar cells 1, between the adjacent solar cells 1a, and between the adjacent solar cells 1 and 1a can be made small. As a result, the power generation efficiency of the solar cell module can be further improved.

  In addition, a plurality of solar cells 1 and 1a can be connected in parallel and in series with a simple structure.

  Furthermore, the number of front side connection tabs 2 is smaller than the number of back side connection tabs 3. Moreover, the center position of the width direction of the surface side connection tab 2 and the center position of the width direction of the back surface side connection tab 3 differ.

  Therefore, when joining the back surface side connection tab 3 to the plurality of solar cells 1, 1 a after joining the surface side connection tab 2 to the plurality of solar cells 1, 1 a, the heat at the time of joining the back surface side connection tab 3 is the surface It becomes difficult to transmit to the side connection tab 2. Thereby, it is prevented that the bonding strength of the front surface side connection tab 2 is lowered when the back surface side connection tab 3 is bonded. Alternatively, when the front-side connection tab 2 is joined to the plurality of solar cells 1, 1 a after the back-side connection tab 3 is joined to the plurality of solar cells 1, 1 a, the heat at the time of joining the front-side connection tab 2 is the back side It becomes difficult to transmit to the side connection tab 3. Thereby, it is prevented that the bonding strength of the back surface side connection tab 3 is lowered when the front surface side connection tab 2 is bonded.

  Therefore, joining of the front surface side connection tab 2 to the plurality of solar cells 1, 1 a and joining of the back surface side connection tab 3 to the plurality of solar cells 1, 1 a are performed in separate steps, and joining of the front surface side connection tab 2. The processing conditions such as the heating temperature and the heating time can be set independently and optimally at the time and when the back surface side connection tab 3 is joined.

  Further, even when the front-side connection tab 2 and the back-side connection tab 3 are simultaneously joined to the solar cells 1, 1 a, heat is hardly transmitted between the front-side connection tab 2 and the back-side connection tab 3. Therefore, it is possible to independently and optimally set the processing conditions at the time of joining the front surface side connection tab 2 and the back surface side connection tab 3.

  As can be seen from these results, the bonding strength of the front surface side connection tab 2 and the back surface side connection tab 3 can be improved, and the range of selection of the manufacturing process is expanded.

  Moreover, since the center position of the width direction of the surface side connection tab 2 and the center position of the width direction of the back surface side connection tab 3 differ, it is prevented that the surface side connection tab 2 and the back surface side connection tab 3 short-circuit. .

(C) Other Arrangement Examples of Connection Tabs Also in the present embodiment, as shown in FIG. Good. In this case, the center position P1 in the width direction of each front surface side connection tab 2 and the center position P2 in the width direction of each back surface side connection tab 3 are different.

  Thereby, the joining of the front surface side connection tab 2 to the plurality of solar cells 1, 1 a and the joining of the back surface side connection tab 3 to the plurality of solar cells 1, 1 a are performed in separate steps. The processing conditions such as the heating temperature and the heating time can be set independently and optimally at the time of bonding and at the time of bonding of the back surface side connection tab 3. As a result, it is possible to improve the bonding strength of the front surface side connection tab 2 and the back surface side connection tab 3.

(4) Fourth Embodiment (a) Overall Configuration of Solar Cell Module FIG. 17 is a schematic plan view of a solar cell module according to a fourth embodiment of the present invention. FIGS. 18A and 18B are a schematic plan view and a schematic side view of a part of the solar cell module according to the fourth embodiment, respectively. FIG. 19 is a cross-sectional view taken along line FF in FIG.

  The solar cell module according to the fourth embodiment is different from the solar cell module according to the third embodiment in the following points.

  In the solar cell module according to the fourth embodiment, as shown in FIGS. 17 to 19, the second set of two solar cells adjacent to the surface and one side of each of the first set of two solar cells 1. Two surface side connection tabs 2 are formed so as to be electrically connected to the surface of 1a. The two surface-side connection tabs 2 extend in parallel with each other along the column direction at positions approximately in the center of the regions obtained by dividing the entire surface of the solar cells 1 and 1a into approximately two equal parts.

  Moreover, the two back surface side connection tabs 3 are formed so as to electrically connect the back surface of each of the first set of two solar cells 1 and the back surface of the second set of two solar cells 1a adjacent to the other side. Has been. The two back surface side connection tabs 3 extend in parallel with each other along the column direction at substantially the center positions of the regions obtained by dividing the entire back surface of the solar cells 1 and 1a into two equal parts.

  Thus, the number of the front surface side connection tabs 2 is equal to the number of the back surface side connection tabs 3. The center position in the width direction of the front surface side connection tab 2 is equal to the center position in the width direction of the back surface side connection tab 3.

  As shown in FIG. 19, the surface-side connection tab 2 is made of a metal wire having a circular cross section. As the surface side connection tab 2, for example, a copper wire is used. The surface of the copper wire is plated with solder that does not contain lead. The diameter of the surface side connection tab 2 is, for example, 0.5 mm.

  The back surface side connection tab 3 is made of a striped metal foil. For example, a copper foil is used as the back side connection tab 3. The surface of the copper foil is subjected to solder plating not containing lead. The width of the back side connection tab 3 is 2 mm, for example, and the thickness is 0.1 mm.

  Thus, in this Embodiment, the surface side connection tab 2 and the back surface side connection tab 3 have a different shape.

(B) Effects of Fourth Embodiment In the solar cell module of the present embodiment, the front surface side connection tab 2 is made of a metal wire having a circular cross section, and the back surface side connection tab 3 is made of a striped metal foil. . Thus, the front surface side connection tab 2 and the back surface side connection tab 3 have different shapes.

  In this case, the diameter of the front surface side connection tab 2 is smaller than the width of the back surface side connection tab 3. Moreover, since the surface side connection tab 2 has a cylindrical outer peripheral surface, incident light is scattered in various directions, and a part of the scattered light is incident from the surface side of the solar cells 1 and 1a. As a result, the optical loss due to the surface-side connection tab 2 can be reduced on the surface side that is the main light incident surface. As a result, the power generation efficiency of the solar cell module is improved.

  On the other hand, since the back surface side connection tab 3 has a large area, its electric resistance is small. Moreover, since the surface side connection tab 2 has a circular cross section, the electrical resistance of the surface side connection tab 2 can be kept small. Thereby, the resistance loss in the surface side connection tab 2 and the back surface side connection tab 3 of a solar cell module can be reduced. As a result, a decrease in the output of the solar cell module is prevented.

  Moreover, the surface side connection tab 2 is extended on the surface of the solar cells 1 and 1a, and the back surface side connection tab 3 is extended on the back surface of the solar cells 1 and 1a. Thereby, since it is not necessary to connect the front surface side connection tab 2 and the back surface side connection tab 3, an edge part connection tab becomes unnecessary. Therefore, the connection structure between the adjacent solar cells 1, between the adjacent solar cells 1a and between the adjacent solar cells 1 and 1a is simplified, and the manufacturing process is simplified. As a result, the manufacturing cost is reduced. Moreover, the space | interval between the adjacent solar cells 1, between the adjacent solar cells 1a, and between the adjacent solar cells 1 and 1a can be made small. As a result, the power generation efficiency of the solar cell module can be further improved.

  In addition, a plurality of solar cells 1 and 1a can be connected in parallel and in series with a simple structure.

(C) Another Example of Connection Tab FIG. 20 is a cross-sectional view showing another example of the surface-side connection tab 2. In the example of FIG. 20, the two surface side connection tabs 2 have a triangular cross section.

  Thereby, incident light is reflected obliquely downward on the side surface of the surface-side connection tab 2 and is incident from the surface side of the solar cells 1 and 1a. As a result, the optical loss due to the surface-side connection tab 2 can be reduced on the surface side that is the main light incident surface. As a result, the power generation efficiency of the solar cell module is improved.

(5) Other Embodiments (A) The number of the front-side connection tabs 2 and the back-side connection tabs 3 is not limited to the number of the above-described embodiments, and may be other numbers. For example, the number of the front side connection tabs 2 may be one, or may be three or more. Further, the number of back side connection tabs 3 may be one or two, or four or more.

  (B) The shape of the front surface side connection tab 2 and the back surface side connection tab 3 is not limited to the shape of the said embodiment, Other shapes may be sufficient. For example, the surface side connection tab 2 may have an elliptical cross section, or may have a polygonal cross section such as a rectangle. Moreover, the back surface side connection tab 3 may have a circular or elliptical cross section, and may have a polygonal cross section.

  (C) The positions of the front surface side connection tab 2 and the rear surface side connection tab 3 are not limited to the positions in the above embodiment, and the front surface side connection tab 2 and the rear surface side connection tab 3 are the front and back surfaces of the solar cells 1 and 1a. It may be formed at other positions.

  (D) The material of the front surface side connection tab 2 and the back surface side connection tab 3 is not limited to copper, and other conductive materials may be used. For example, the front surface side connection tab 2 and the back surface side connection tab 3 may be formed of another metal material such as aluminum or stainless steel, or may be formed of an alloy material.

  (E) The solar cells 1 and 1a are not limited to a hybrid structure using an amorphous silicon film and single crystal silicon, and may have other structures. For example, a polycrystalline silicon film or a microcrystalline silicon film may be used instead of the amorphous silicon film. Moreover, the solar cells 1 and 1a may have a single crystal type, a polycrystalline type, an amorphous type structure, or the like instead of the HIT type structure.

  (F) The shape of the solar cells 1 and 1a is not limited to a square, and the solar cells 1 and 1a may have other shapes such as a rectangle, a circle, an ellipse, and a polygon.

  (G) As the back surface member 6, similarly to the front surface member 5, a translucent material such as transparent glass or a transparent film may be used.

  (H) The front surface side connection tab 2 and the back surface side connection tab 3 are preferably formed so as to extend over the entire length of the solar cells 1 and 1a in the column direction, but are not limited thereto. The back surface side connection tab 3 may be formed in a partial region in the column direction of the solar cells 1 and 1a.

  (I) In the second embodiment, two solar cells 1 are connected in parallel, but three or more solar cells 1 may be connected in parallel.

  (J) In the third and fourth embodiments, two solar cells 1 are connected in parallel and two solar cells 1a are connected in parallel, but three or more solar cells 1 are connected in parallel. Three or more solar cells 1a may be connected in parallel.

  (K) The collector electrodes 15p and 15n may not have the bus bar electrode portions 13p and 13n. In this case, the front surface side connection tab 2 and the back surface side connection tab 3 are joined to the finger electrode portions 14p and 14n.

(6) Correspondence between each component of claim and each part of embodiment In the above embodiment, the surface of solar cell 1, 1a corresponds to the first surface, and the back surface of solar cell 1, 1a is the second surface. The collector electrode 15p of the solar cell 1 corresponds to the first electrode, the collector electrode 15n of the solar cell 1 corresponds to the second electrode, the collector electrode 15n of the solar cell 1a corresponds to the first electrode, The collector electrode 15p of the battery 1a corresponds to the second electrode. The front surface side connection tab 2 corresponds to a first connection member, and the back surface side connection tab 3 corresponds to a second connection member. Furthermore, the solar cell 1 corresponds to the first solar cell, the solar cell 1a corresponds to the second solar cell, the positive electrode corresponds to the first polarity electrode, and the negative electrode corresponds to the second polarity electrode. To do.

  Further, the diameter or width of the front-side tab electrode 2 corresponds to the maximum width of the first connection member, the width of the back-side tab electrode 3 corresponds to the maximum width of the second connection member, and the diameter or width of the front-side tab electrode 2 The thickness corresponds to the maximum thickness of the first connection member, and the thickness of the back-side tab electrode 3 corresponds to the maximum thickness of the second connection member.

  The solar cell module according to the present invention can be used for various power sources and the like.

1 is a schematic plan view of a solar cell module according to a first embodiment of the present invention. (A), (b) is a typical top view and typical side view of a part of solar cell module concerning a 1st embodiment, respectively. It is CC sectional view taken on the line of Fig.2 (a). It is a top view of the surface side of one solar cell. It is a top view of the back surface side of one solar cell. It is a top view of the surface side of one solar cell. It is a top view of the back surface side of one solar cell. It is typical sectional drawing of a solar cell. It is typical sectional drawing of a solar cell. It is sectional drawing which shows the other example of arrangement | positioning of a surface side connection tab and a back surface side connection tab. It is a schematic plan view of the solar cell module according to the second embodiment of the present invention. (A), (b) is a typical top view and typical side view of a part of solar cell module concerning a 2nd embodiment, respectively. It is the DD sectional view taken on the line of Fig.12 (a). It is sectional drawing which shows the other example of arrangement | positioning of a surface side connection tab and a back surface side connection tab. It is a typical top view of the solar cell module which concerns on the 3rd Embodiment of this invention. (A), (b) is a typical top view and typical side view of a part of solar cell module concerning a 3rd embodiment, respectively. It is a schematic plan view of the solar cell module according to the fourth embodiment of the present invention. (A), (b) is the typical top view and typical side view of a part of solar cell module which concerns on 4 embodiment, respectively. It is the FF sectional view taken on the line of Fig.18 (a). It is sectional drawing which shows the other example of the surface side connection tab. (A), (b) is typical sectional drawing and typical side view which show the structure of the conventional solar cell module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1a Solar cell 2 Surface side connection tab 2a, 2b, 2c, 2d, 3a End part connection tab 2e, 2f Electric power cable 3 Back surface side connection tab 4 Sealing material 5 Surface member 6 Back surface member 11 n-type single crystal silicon wafer 12, 12a Surface electrode 13p, 13n Bus bar electrode part 14p, 14n Finger electrode part 15p, 15n Collector electrode 21 i-type amorphous silicon film 22 p-type amorphous silicon film 23 i-type amorphous silicon film 24 n-type non-electrode Crystalline silicon film 25, 25a Back electrode P1, P2 Center position

Claims (9)

A plurality of solar cells having a first electrode and a second electrode on the first surface and the second surface, respectively;
One or more strip-shaped first connection members joined to the first electrode of the first surface of each solar cell;
A strip-shaped one or more second connection members joined to the second electrode of the second surface of each solar cell;
Formed so that the first connection members of a plurality of adjacent solar cells are continuous, and formed so that the second connection members of a plurality of adjacent solar cells are continuous,
The shape of each 1st connection member of each solar cell and the shape of each 2nd connection member differ, The solar cell module characterized by the above-mentioned. 2. The solar cell module according to claim 1, wherein the maximum width of each first connection member of each solar cell is smaller than the maximum width of each second connection member. The solar cell module according to claim 2, wherein the maximum thickness of each first connection member of each solar cell is larger than the maximum thickness of each second connection member. 4. The solar cell module according to claim 1, wherein each first connection member of each solar cell has a substantially circular cross section, and each second connection member has a flat plate-like cross section. The first electrode and the second electrode are metal electrodes partially formed on the first surface and the second surface, respectively.
The sun according to any one of claims 1 to 4, wherein a center position in a width direction of at least a part of the first connection member of each solar cell is different from a center position in the width direction of the second connection member. Battery module. The first electrode and the second electrode are metal electrodes partially formed on the first surface and the second surface, respectively.
6. The solar cell module according to claim 1, wherein the number of the first connection members and the number of the second connection members of each solar cell are different. The plurality of solar cells includes a plurality of sets constituted by adjacent first and second solar cells,
The first electrode of the first surface of each first solar cell has a first polarity, the second electrode of the second surface of each first solar cell has a second polarity; The first electrode on the first surface of each second solar cell has the second polarity, and the second electrode on the second surface of each second solar cell has the first polarity. And
The first connection member of the first solar cell of each set and the first connection member of the second solar cell of the set are formed to be continuous, and the first solar cell of each set The second connection member is formed so as to be continuous with the second connection member of the second solar cell in another set adjacent to one side, and the second connection of the second solar cell in each set. The solar cell according to claim 1, wherein the member and the second connection member of the first solar cell of another set adjacent to the other side are continuous. module. The plurality of solar cells includes a plurality of sets composed of a plurality of solar cells adjacent to each other sequentially,
The first electrode of the first surface of each solar cell has a first polarity, the second electrode of the second surface of each solar cell has a second polarity;
The first connection members of the plurality of solar cells in each set are formed to be continuous, the second connection members of the plurality of solar cells in each set are formed to be continuous, and the first of each set The solar cell module according to claim 1, wherein the connection member is connected to another set of the second connection members adjacent to each other. The plurality of solar cells alternately include a first set composed of a plurality of first solar cells sequentially adjacent to each other and a second set composed of a plurality of second solar cells sequentially adjacent to each other,
The first electrode of the first surface of each first solar cell has a first polarity, the second electrode of the second surface of each first solar cell has a second polarity; The first electrode on the first surface of each second solar cell has the second polarity, and the second electrode on the second surface of each second solar cell has the first polarity. And
The first connection member of each of the first sets of the plurality of first solar cells and the first connection member of the second set of the plurality of second solar cells adjacent to one side are formed to be continuous. The second connection members of the first sets of the plurality of first solar cells and the second connection members of the second set of the plurality of second solar cells adjacent to the other side are continuous with each other. The solar cell module according to any one of claims 1 to 6, wherein the solar cell module is formed.

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