JP2015207598A - Solar cell module, solar cell, and inter-element connection body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell module having high energy conversion efficiency and high yield.SOLUTION: A first electrode disposed on a light receiving side of an n-type single crystal silicon substrate 1 provided with a photoelectric conversion part includes tab lines as inter-element bodies respectively connected to bus electrodes 5B provided at continuing two corner parts of a first principal plane 1A, a solar cell 10 having grid electrodes 1G connected to the bus electrodes 5B, and bus electrodes 5B at two corners of the solar cell 10.

Description

  The present invention relates to a solar cell module, a solar cell, and an inter-element connector used for the solar cell module.

  Photoelectric conversion devices are attracting attention as a next-generation power generation method because of their low environmental burden and operating cost. Conventionally, a plurality of solar cells having a surface electrode on a first surface forming a light receiving surface and a back electrode on a second surface, which is the back surface, are arranged side by side and adjacent to the light receiving surface electrode of one solar cell. A solar cell module is disclosed in which a back electrode of another solar cell is connected using a strip-shaped tab wire as an inter-element connection body, and one solar cell and another adjacent solar cell are connected in series.

  The strip-shaped tab wire is generally arranged extending in the connecting direction on the light receiving surface and the back surface of the solar cell. For this tab wire, generally, a metal surface with high conductivity such as copper foil is coated with solder. In the connection of the tab wire, the tab wire is placed on the solar cell coated with solder and heated, and the tab wire and the solar cell are connected by being crimped partially or over the entire length.

  In such a tab line, the tab line provided on the light receiving surface covers the light receiving surface of the solar cell. However, incident light incident on the solar cell can be increased by narrowing the width to some extent. On the other hand, the greater the cross-sectional area of this tab line, the smaller the resistance loss and the more the output efficiency improves. Therefore, it is only necessary to increase the incident light by reducing the width of the tab line, while suppressing the increase in resistance loss by increasing the thickness. However, when the thickness of the tab wire is increased, the thermal stress generated due to the difference in the coefficient of linear expansion between the tab wire and the solar cell is increased at the time of solder connection, and cell cracking may occur. In addition, there is a possibility that the tab wire portion will be the starting point in the pressing process at the time of sealing, and that cracking may occur, solar cell warpage, cell cracking, or electrode peeling may occur.

  Also, in general, in order to effectively collect electrons and holes generated in the solar cell surface by the incidence of sunlight, a plurality of tab wires are provided with appropriate intervals between both ends of the solar cell. It extended straight and was provided across the front and back of adjacent solar cells. For this reason, the light receiving surface is obstructed by the tab wire, so that sunlight cannot reach the solar cell, and the power generation efficiency is low according to the occupied area.

  On the other hand, by connecting the tabs between the cells in a three-dimensional manner, the play of the connection tabs is increased. As a result, the stress on the connection tabs due to the cyclic change of the module temperature is alleviated, and the thermal stress is reduced. A technique for preventing breakage of a connection tab caused by the above has been disclosed (Patent Document 1).

International Publication No. 2011/077755

  In such a solar cell module, when the solar cells are arranged and electrically wired, the tab wire is already connected from the light receiving surface of one of the solar cells between the cells electrically connected by the tab wire. It must be connected to the back of one solar cell. In this case, in order to alleviate the stress stress on the solar battery cells caused by the bending of the tab, it is necessary to take a distance of about several mm between the solar battery cells electrically connected in series in the solar battery module. However, in this blank area between the solar cells, a large proportion of the incident light is reflected and goes out of the solar cell module, which causes a problem of reducing the energy conversion efficiency of the solar cell module. It was.

  Furthermore, since the tab wire has to be installed on the surface of the solar battery cell, there is a problem that the tab wire reflects light incident on the solar battery cell to reduce the energy conversion efficiency of the solar battery module. .

  The present invention has been made in view of the above, and an object thereof is to obtain a solar cell module having high energy conversion efficiency and high yield.

  In order to solve the above-described problems and achieve the object, the solar cell module of the present invention is formed on each of the semiconductor substrate having the photoelectric conversion unit and the first and second main surfaces facing each other of the semiconductor substrate. A first electrode disposed on the light receiving surface side, the first electrode disposed on the light receiving surface side; a bus electrode provided at two consecutive corners of the first main surface; and a grid electrode connected to the bus electrode And an inter-element connection body connected to each bus electrode.

  According to the present invention, by providing the tab line connection portion between the solar cells at the corner portion of the solar cell, the shadow loss is reduced, and the solar cell is not subjected to stress due to the inter-element connection body. There exists an effect of improving the energy conversion efficiency of a battery module.

1A and 1B are diagrams schematically showing a solar cell used in the solar cell module according to Embodiment 1, wherein FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along line AA in FIG. FIG. 2 is a diagram showing an inter-element connector used in the solar cell module. FIG. 3 is a diagram schematically showing a string of solar cells used in the solar cell module. 4 is a cross-sectional view taken along line BB in FIG. FIG. 5 is a perspective view showing a string of the solar cell. FIG. 6 is a cross-sectional view showing the solar cell module according to Embodiment 1. FIG. 7 is a diagram schematically showing a solar cell used in the solar cell module according to Embodiment 2, wherein (a) is a plan view and (b) is a cross-sectional view taken along line AA of (a). FIG. 8 is a diagram showing an inter-element connection body used in the solar cell module. FIG. 9 is a diagram schematically showing a string of solar cells used in the solar cell module, where (a) is a top view, (b) is a cross-sectional view taken along C1-C1 in (a), and (c) is ( It is C2-C2 sectional drawing of a). FIG. 10 is a plan view of the solar cell module. FIG. 11 is a diagram showing a modified example of the inter-element connection body used in the solar cell module, where (a) is an inter-element connection body used in a straight portion, and (b) is an inter-element connection used in a corner portion. Is the body. FIG. 12 is a scatter diagram showing the relationship between the conversion efficiency of the solar cell module and the width of the blank area between solar cells. FIG. 13 is a diagram schematically illustrating a solar cell used in the solar cell module according to Embodiment 3, wherein (a) is a plan view and (b) is an AA cross-sectional view of (a). FIG. 14 is a diagram showing an inter-element connection body used in the solar cell module, in which (a) shows a main body portion and (b) shows a current collecting contact. FIG. 15 is a view showing an upper surface of the inter-element connector used in the solar cell module. FIG. 16 is a diagram showing a main part of the solar cell module. FIG. 17 is a diagram illustrating a main part of a modification of the solar cell module.

  Embodiments of a solar cell module according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment, In the range which does not deviate from the summary, it can change suitably. In the drawings shown below, the relationship between the thickness and width of each layer, the ratio of the thickness of each layer, or the scale of each member may be different from the actual for easy understanding, and the same applies to the drawings. Further, even a plan view may be hatched to make the drawing easy to see.

Embodiment 1 FIG.
1A and 1B are diagrams schematically showing a solar cell used in a solar cell module according to Embodiment 1 of the present invention, in which FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along line AA in FIG. It is. FIG. 2 is a diagram showing an inter-element connector used in the solar cell module, and FIG. 3 is a diagram schematically showing a string of solar cells used in the solar cell module. The solar cell module of the present embodiment includes two corner portions C ₀₁ and C ₀₂ on the light receiving surface 1A side which is the first main surface of the n-type single crystal silicon substrate 1 as a semiconductor substrate constituting the solar cell 10. A bus electrode 5B is provided on the grid electrode 5G, and grid electrodes 5G are formed radially from the bus electrode 5B. As will be described in detail later, the grid electrode 5G is long, and thus is preferably formed by copper plating having a low resistivity.

The tab wire 20 as the inter-element connection body is a linear conductor as shown in the perspective view of FIG. One end is connected to the bus electrode 5B, and the other end is connected to the back electrode 6 which is the second electrode provided on the second main surface of the solar cell. All connections are soldering or welding. Although this tab line 20 has a very simple configuration, a blank region V generated at the corner portions C ₀₁ and C ₀₂ of the solar battery cell 10 is used as a connection region. This blank area V is due to the wafer shape with the four corners cut off.

As shown in FIG. 3, the first to third solar cells 10 a to 10 c which are the solar cells 10 are connected with high density and have a string S with less light-blocking regions causing shadow loss by the tab wires 20. To do. A BB cross section of the string S shown in FIG. 3 is shown in FIG. 4, and a perspective view is shown in FIG. The tab wire 20 extends from the back surface of the solar battery cell 10, and in the blank region V generated at the corner portions C ₀₁ and C ₀₂ of the first solar battery cell 10 a and the second solar battery cell 10 b, the tab wire 20 and the bus electrode. 5B is bonded with solder.

  Then, as shown in the cross-sectional view of FIG. 6, sheets such as an ethylene vinyl acetate resin sheet are provided on the front surface side and the back surface side of the string S that is the connection body of the plurality of solar cells 10 illustrated in FIGS. A sealing material 50 is disposed, and a light-receiving surface side main surface material 40 such as glass is bonded to the front surface (light-receiving surface) side through the sealing material 50, and weather-resistant polyethylene is connected to the back surface side. A back side main surface material 30 such as a terephthalate resin sheet is bonded.

  Further, the structure sandwiched between the light receiving surface side main surface material 40 and the back surface side main surface material 30 is supported by a frame made of metal or the like, and the current lead line is connected from the cut line between the sealing material 50 and the back surface side main surface material 30. The light receiving element module 100 is configured by being taken out on the back surface through a box.

  In this solar cell 10, an n-type single crystal silicon substrate 1 as a first conductivity type semiconductor substrate is used. In particular, for a single crystal silicon wafer, a single crystal silicon ingot pulled up into a cylindrical shape by the Czochralski method is cut into a square shape in a direction perpendicular to the vertical direction of the cylinder, leaving arc portions at four corners. For this reason, a single crystal silicon wafer used for a crystalline silicon solar cell generally has a quadrangular shape with four corners omitted as shown in FIG. 1A, and this planar shape is used in this embodiment. Such a shape in which four corners are cut off is often used, and is almost rectangular. However, other shapes such as a triangle, a hexagon, and an octagon may be used.

A curved portion for connecting the tab wire 20 from the light receiving surface 1A side to the back surface 1B is disposed in a blank region V generated at the corner portions C ₀₁ and C ₀₂ of the solar battery cell 10. Thus, even if the interval between the solar battery cells 10 is reduced, it is possible to ensure a sufficient interval between the curved portions, and the stress stress at the time of sealing the solar cell module is small. Moreover, since the tab wire 20 is not disposed on the light receiving surface 1A side of the solar battery cell 10, a high short circuit current value can be obtained as compared with a general comb-like electrode structure in which the tab wire is installed on the solar battery light receiving surface. Can do.

  In this way, it is possible to shorten the width of the blank area V between the solar cells without giving stress to the solar cells when the solar cell module is sealed, and the energy conversion of the solar cell module can be easily performed. Solar cells with high efficiency can be manufactured.

  Hereinafter, the solar battery cell constituting the solar battery module of Embodiment 1 will be described in detail.

  As such a solar battery cell 10, a crystalline silicon light-receiving element using crystalline silicon having a pn junction, a compound light-receiving element using a compound semiconductor such as gallium arsenide, or the like can also be used. The pn junction may be formed by impurity diffusion, or may be a heterojunction element formed by a thin film such as amorphous silicon or microcrystalline silicon.

As shown in FIG. 1A, in a region on the light receiving surface 1A side of the solar battery cell 10, a bus electrode 5B as a current collector provided in two corner portions C ₀₁ and C ₀₂ and the bus electrode Grid electrodes 5G extending radially from 5B are formed. On the back surface 1B side, two back surface electrodes 6 are formed as the other electrode. The bus electrode 5B and the grid electrode 5G are made of nickel, tin, copper, or the like for the purpose of reflecting the light transmitted through the solar battery cell 10 as a part in contact with the translucent conductive film 4 of the photoelectric conversion unit. It is desirable to use a metal material mainly containing a material having a high light reflectivity in a wide wavelength range such as silver, gold, a mixture thereof, and an alloy, and form a reflective metal layer. By laminating a barrier layer or the like that suppresses the reaction with the metal material or the reflective metal layer as the second layer on the reflective metal layer, electrical conduction in the grid electrode 5G and the bus electrode 5B can be improved. As a material for this purpose, nickel, aluminum, tin, copper, silver, a mixture thereof, an alloy, or the like can be used. In addition to this, for example, in the case of a light receiving element in which a semiconductor junction is formed by a heterojunction, a laminate of a translucent electrode formed of indium oxide or the like and aluminum, silver, gold, or the like may be used.

  As the outermost layer of the grid electrode 5G and the bus electrode 5B, it is desirable to use a material suitable for connecting to the inter-element connector when modularizing. For example, when connecting an element and an inter-element connector using solder, it is desirable to use copper, tin, silver, or the like.

  The grid electrode 5G and the bus electrode 5B according to the first embodiment are electrodes that collect electric charges generated by photocarrier generation from the semiconductor substrate and collect current, and are arranged at appropriate intervals. The pattern of the grid electrode 5G varies depending on a junction formed by doping, a heterojunction, a substrate resistance, or the like. For example, a linear shape portion having a width of about 0.05 to 0.5 mm and extending in a predetermined direction is It is desirable that the electrodes are arranged in a direction orthogonal to the extending direction of the electrodes with a period of 2 to 2.5 mm. On the other hand, the back electrode 6 is desirably wide or formed on the entire surface.

  Further, since the bus electrode 5B is connected to the tab wire 20, the bus electrode 5B has a width sufficient for connection, for example, about 1 to 2 mm. This width is preferably smaller than the diffusion length of minority carriers in the substrate.

  The back electrode 6 is preferably made of a metal material mainly containing Ag, aluminum, and copper and a laminate thereof.

  In the solar cell 10 of the present embodiment, the diffusion length of minority carriers needs to be longer than the distance between the grid electrodes 5G in order to increase the current extraction efficiency. For this reason, the element surface is inactivated (passivation). It is preferable that As an example of such an element structure, a heterojunction solar cell made of an amorphous silicon film or microcrystalline silicon formed on a single crystal silicon substrate is desirable. As the semiconductor substrate, an n-type single crystal silicon substrate 1 is used, and intrinsic amorphous silicon layers 2i and 3i having a thickness of about 5 nm are formed on both surfaces thereof, and stacked on each of them to form p-type amorphous silicon. Layer 2p and n-type amorphous silicon layer 3n are formed.

  Further, a translucent conductive film 4 such as indium oxide is formed on the outermost layer on the light receiving surface 1A side and the back surface 1B side. On the light receiving surface 1A side, the grid electrode 5G and the bus electrode 5B are formed on the translucent conductive film 4. A back electrode 6 is formed on the translucent conductive film 4 on the back surface 1B side. On the light receiving surface 1A side, an amorphous silicon nitride film or a high refractive index film such as titanium dioxide formed as a reflection preventing film by sputtering or CVD may be laminated.

  According to the solar cell module of the present embodiment, it is not necessary to provide the blank region V between the solar cells by bending the tab wire, so that the energy conversion efficiency of the solar cell module is improved.

  In addition, according to this configuration, the solar cell string can be formed and the cell interval can be reduced in the same process as the installation of the tab wire used in a general comb-shaped electrode structure, so that the manufacturing process is easy. become.

  In addition, the grid electrodes are arranged so that the distance between the grid electrodes does not become too large by branching away from the current collector in order to suppress resistance loss due to carrier conduction in the lateral direction of the substrate in the solar battery cell. Is desirable.

  As described above, according to the present embodiment, the tab line connecting portion between the solar cells is provided in the blank area in the corner portion of the solar cell, so that the stress caused by the inter-element connector is applied to the solar cell. Without giving, there is an effect that the area of the blank area between the solar cells is reduced to suppress the light reflection loss and to increase the energy conversion efficiency of the solar cell module.

Embodiment 2. FIG.
In the second embodiment, an example in which bus electrodes 15B are provided at the four corners of the light receiving surface 1A and the current collectors are provided at four locations will be described. 7: is a figure which shows typically the solar cell used for the solar cell module by Embodiment 2 concerning this invention, (a) is a top view, (b) is AA sectional drawing of (a). It is. FIG. 8 is a diagram showing a tab line as an inter-element connection body used in the solar cell module, FIG. 9 is a diagram schematically showing a string of solar cells used in the solar cell module, (a) (B) is a C1-C1 sectional view of (a), (c) is a C2-C2 sectional view of (a). In the solar cell module of the present embodiment, bus electrodes 15B are provided at the four corners of the light receiving surface 1A, and the grid electrodes 15G connected to the bus electrodes 15B extend radially toward the center of the light receiving surface 1A.

  7A is a plan view when the pattern of the collecting electrode 15 is formed on the light receiving surface 1A of the solar battery cell 10, and FIG. 7B is a cross-sectional view taken along the line AA. The current collecting electrode 15 includes a bus electrode 15B provided at the four corners of the solar battery cell 10 and a grid electrode 15G extending radially from the bus electrode 15B. In addition, a back electrode 6 is provided on the back surface 1B opposite to the first main surface which is the light receiving surface 1A, that is, on the second main surface. The tab wire 20 as the inter-element connection body includes a first conductor portion connected to the bus electrode 15B and a second conductor portion connected to the back electrode 6 of the adjacent solar battery cell 10. The solar battery cell 10 is connected.

  The tab wire 20 as the inter-element connection body is composed of a pair of symmetrical linear bodies provided on the same plane as shown in a top view in FIG. Each linear body 21 includes, as a first conductor portion, a vertical tab line 21a connected to the back electrode 6, a horizontal tab line 21b orthogonal to the vertical tab line 21a, a corner portion 21c, and a horizontal tab line 21b. A second conductor portion having a vertical tab line 21d extending in a direction perpendicular to the other end of the second conductor portion. Further, the corner portions 21c at both ends of the vertical tab wire 21d have a triangular shape or a trapezoidal shape, and a contact as a current collecting portion having a thickness similar to that of the solar battery cell 10 having a thickness of about 0.1 mm to 0.2 mm. It has a pallet 22. The tab wire 20, the contact pallet 22, and the corner portion 21 are soldered. The bus electrode 15B is connected to the contact pallet 22. Since the current concentrates at the soldering location and resistance loss occurs, soldering may be performed at a plurality of locations in order to reduce it. In order to collect the current on the light receiving surface 1A side of the solar battery cell 10 from the four corner portions of the solar battery cell 10, the grid electrode 15G extends radially from the four corners. As described above, the vertical tab line 21a corresponds to the first conductor portion, and the horizontal tab line 21b, the corner portion 21c, the vertical tab line 21d, and the like correspond to the second conductor portion. The tab wire 20 as the inter-element connection body is connected to the back electrode 6 at the first conductor portion, and connected to the bus electrode 15B provided on the light receiving surface side of the adjacent cell at the second conductor portion, and the elements are connected in series. To do.

  In manufacturing the tab wire 20 of the present embodiment, the metal wires cut into the respective lengths are bonded by thermocompression bonding or soldering. The material is a highly conductive metal such as copper, silver, or aluminum. Alternatively, the tab line 20 may be produced by bending one metal line from the vertical tab line 21a, the horizontal tab line 21b, and the vertical tab line 21d. Further, by cutting out from one metal plate by shearing or laser processing, the tab wire 20 having a constant thickness can be produced, and stress stress when sealing the solar battery cell can be alleviated.

  The contact pallet 22 constituting the current collector is manufactured in a shape that does not interfere with the four corners of the single crystal silicon wafer. The material of the contact pallet 22 is a metal such as silver, copper, or aluminum as in the case of the metal wire. In order to increase the current gain of the solar battery cell by light reflection, the entire surface may be plated with solder. The contact pallet 22 is connected to the bus electrode 15B via a conductive thin piece 24 formed of a conductive belt-like body such as a copper foil.

  The photovoltaic cell 10 has an insulating layer 23 sandwiched between the tab wire 20 and prevents the p side and the n side of the photovoltaic cell 10 from being electrically short-circuited. The insulating layer 23 is produced by coating an insulating resin such as polyimide resin on the tab wire 20 or sandwiching an insulating sheet between the solar battery cell 10 and the tab wire 20. In FIG. 9B, the right solar cell 10 is bonded by soldering the back electrode 6 to the vertical tab wire 21 a of the tab wire 20. The left solar cell 10 is fixed to the horizontal tab wire 21b through the insulating layer 23. The contact pallet 22 extends between the two solar cells 10 to the surface of the solar cell, and is connected to the bus electrode 15B of the left solar cell 10 by the conductive thin piece 24. In this way, the conductive thin piece 24 is connected to the bus electrode 15B at the four positions of the tab wire 20, and the connection between the two solar cells 10 is made.

  On the contact pallet 22, a bus electrode 15B connected to a grid electrode 15G as a light-receiving surface collecting electrode extending from the light-receiving surface 1A of the solar battery cell 10 can be soldered or electrically connected such as thermocompression bonding. Glued by.

Since the collector electrode 15 on the light receiving surface 1A side of the solar battery cell 10 needs to collect current over a long distance from the center of the solar battery cell 10 to the four corners, the current collector electrode 15 on the light receiving surface 1A has a resistivity. It is desirable to use a low material. The resistivity of the grid electrode is desirably 2.0 × 10 ⁻⁶ Ωcm or less.

When a grid electrode using an Ag paste having a specific resistance of 1.6 × 10 ⁻⁵ Ωcm is formed on a Si substrate having a size of 156 mm × 156 mm, the cross section of the grid electrode has a rectangular shape with a width of 80 μm and a height of 40 μm. The line resistance is 0.25 Ω / cm. At this time, the fill factor in the electrode structure of the solar battery cell 10 was reduced by 4/100 compared to the comb-like electrode structure with two bus bars (grid spacing 2 mm). This corresponds to a 5% decrease in solar cell output.

On the other hand, when the copper (1.68 × 10 ⁻⁶ Ωcm) electrode using the plating method was used, the decrease in the fill factor was 3/1000 compared to the comb-like electrode structure with two bus bars. .

  Thereby, even when the current collection distance is long, the resistance loss can be suppressed. In particular, by forming the collecting electrode 15 using a copper plating method having a low resistivity and an inexpensive price, even when the grid electrode 15G connected to the tab wire 20 is long, the energy loss due to the resistance is kept low. be able to.

  FIG. 10 is a plan view showing the entire solar battery module 100 when the solar battery cells 10 shown in FIGS. 7A and 7B are electrically connected in series. In FIG. 10, the sealing material 50, the light receiving surface side main surface material 40, and the back surface side main surface material 30 are omitted. The solar cells connected in a string form are configured in three vertical rows. The two solar cells 10S1 and 10S2 positioned at the folded portions where the strings S and the strings S are connected are shown in FIG. The tab lines 20 are connected in a state of being rotated 90 degrees, and are arranged so that the vertical tab lines 21a face the arrangement direction of the strings S. An insulating layer may be interposed where the tab wires 20 interfere with each other. In this way, electrical connection to the lateral cells is made. Reference numeral 20R denotes a current extraction unit of the solar cell module 100.

  The string S of solar cells 10 connected in this manner is placed on a back sheet, and a cover glass is laminated on the back sheet with a sealing material such as EVA (Ethylene Vinyl Acetate) resin interposed between them, as shown in FIG. Such a solar cell module is produced.

  As shown in FIGS. 11A and 11B, the tab line 20 as the inter-element connection body is the same as the tab line shown in FIG. 8, but the vertical tab lines 21a are connected to the intermediate connection portion 21e. And a pair of symmetrical linear bodies may be integrated. In this case, the tab wire 20 connected to the solar cell 10n1 in the normal row is connected by the intermediate connection portion 21e and the tip connection portion 21f, and a symmetric pair of linear bodies is integrated, as shown in FIG. The shape is as follows. And as shown in FIG.11 (b), the opening location O is removed by removing the vertical tab line 21d parallel to the vertical tab line 21a, the tab line 20 connected to the photovoltaic cell 10S1 of the folding | turning part on the right side. It is formed so as not to interfere with the tab wire 20 connected to the adjacent normal row solar cells 10n1 shown in FIG. By using such a tab wire, a solar cell module can be formed very easily. Moreover, since the first and second conductor portions are continuously formed on the same plane and can be formed without bending the tab wire, the processing is easy and the stability of the shape can be maintained. Moreover, the workability of mounting the solar cell module including the processing of the tab wire is also good. In this way, without applying stress due to the tab line to the solar cells, the area of the blank region between the solar cells can be reduced to suppress the light reflection loss, and the energy conversion efficiency of the solar cell module can be increased.

  The result of measuring the relationship between the conversion efficiency and the cell interval of the solar cell module shown in FIG. 12 also applies to this embodiment. As can be seen from this figure, in the solar cell module of the present embodiment in which the cell interval W can be made extremely small as about 0.1 mm, the conversion efficiency is improved by 20%.

  According to such a configuration, the current from the light receiving surface 1 </ b> A of the solar battery cell 10 is collected at the bus electrode 15 </ b> B portions provided at the four corners of the solar battery cell 10, and the back surface of the adjacent solar battery cell 10. Since it is connected to the back surface electrode 6 through the vertical tab 21a on the 1B side, it is not necessary to provide a blank area between the solar cells and the space between the cells can be narrowed. Therefore, the light reflection loss to the outside of the cell in the blank region V of the solar cell module can be reduced, and the energy conversion efficiency of the solar cell module can be increased.

  In addition, compared to a general comb-like electrode pattern, there is less area for soldering the tab wire on the solar cell, so there is less warpage of the solar cell due to soldering, less physical damage, and higher yield. A solar cell module can be manufactured.

Embodiment 3 FIG.
In the third embodiment, an example is shown in which wedge-shaped bus electrodes 25B are provided from the four corners of the light receiving surface 1A toward the center, and the current collectors are provided at four locations. FIG. 13: is a figure which shows typically the solar cell used for the solar cell module by Embodiment 3 concerning this invention, (a) is a top view, (b) is AA sectional drawing of (a). It is. 14 (a) and 14 (b) are exploded views showing a tab line as an inter-element connection body used in the solar cell module, FIG. 15 is a top view of the inter-element connection body, and FIG. It is a principal part top view of a battery module. In the solar cell module 100 of the present embodiment, bus electrodes 25B are provided in a wedge shape from the four corners of the light receiving surface 1A, and the current collecting contact 26 as a wedge-shaped conductor foil from the tab wire 20 so as to overlap the bus electrode 25B. Are stretched and connected. The current collecting contacts 26 extend from the corners of the four corners of the solar battery cell 10 toward the center at an angle of 45 degrees with respect to the long side of the solar battery cell 10. A grid electrode 25G extends from the bus electrode 25B below each current collecting contact 26 at an angle of 45 degrees. The current collecting contact 26 may be considered to correspond to the conductive thin piece 24 in the first embodiment.

  FIG. 13A is a plan view when the pattern of the collecting electrode 25 is formed on the light receiving surface of the solar battery cell 10, and FIG. The current collecting electrode 25 includes a wedge-shaped bus electrode 25B provided so as to go from the four corners of the solar battery cell 10 toward the center, and a grid electrode 25G that intersects the bus electrode 25B and extends concentrically. Here, the grid electrode 25G is connected to the bus electrode 25B through a plurality of connecting portions.

  The tab wire 20 as the inter-element connection body includes a main body portion composed of a linear body 21 composed of a pair of symmetrical linear bodies, and a current collecting contact 26 connected to the linear body 21. Consists of. 14A shows a cross-sectional view of the main body, FIG. 14B shows the current collecting contact 26, and FIG. 15 shows an overall view. Each linear body 21 constituting the main body is the same as the linear body 21 of the second embodiment, and includes a vertical tab line 21a, a horizontal tab line 21b orthogonal to the vertical tab line 21a, a corner part 21c, and further A vertical tab line 21d extending in a direction orthogonal to the other end of the horizontal tab line 21b. Further, the corner pallets 21c at both ends of the vertical tab wire 21d have a triangular shape or a trapezoidal shape, and a contact pallet as a current collecting portion having a thickness similar to that of a solar cell having a thickness of about 0.1 mm to 0.2 mm. 22 (similar to FIG. 9C but not shown). The tab wire 20 and the contact pallet are connected by soldering, and the current collecting contact 26 is soldered to the contact pallet 22, while soldering is performed so as to cover the wedge-shaped bus electrode 25B. FIG. 16 is a view showing the main part of the solar cell module to which the current collecting contacts 26 are connected in this way.

  Although current is concentrated at the soldered portion and resistance loss occurs, the current collecting resistance is greatly reduced because the bus electrode 25B is backed by the current collecting contact 26. Since the current on the light-receiving surface 1A side of the solar battery cell 10 is collected by the current collecting contact 26 extending from the four corners of the solar battery cell toward the center, the current from the grid electrode 25G is efficiently collected.

  Since other parts are formed in the same manner as in the second embodiment, description thereof is omitted here.

  The current collecting electrode 25 on the light receiving surface 1A side of the solar battery cell 10 needs to collect current over a long interval from the center of the solar battery cell 10 to the four corners. In this embodiment, the current collecting contact 26 is the solar battery. Since it is formed in a wedge shape toward the center of the cell 10, the current collecting resistance by the light receiving surface collecting electrode is only for the grid electrode 25G, and the energy loss due to the resistance can be kept low.

  As described above, according to the present embodiment, since the current collecting contact 26 is provided on the solar battery cell 10, as compared with the example shown in the first and second embodiments. In addition, the length from the grid electrode 25G to the tab wire (current collection contact 26) as the current collection unit is shortened. Therefore, for the grid electrode 35G, besides the copper plating, a screen printing method using an Ag paste or the like can be used, and the manufacturing process can be simplified.

  The result of measuring the relationship between the conversion efficiency and the cell interval of the solar cell module shown in FIG. 12 also applies to this embodiment. As can be seen from this figure, in the solar cell module of the present embodiment in which the cell interval W can be made extremely small as about 0.1 mm, the conversion efficiency is improved by 20%.

  Thereby, the space | interval between photovoltaic cells is short, and a solar cell module with high energy conversion efficiency can be manufactured.

  Furthermore, as shown in a modified example in FIG. 17, the grid electrodes 35G may be formed alternately by shifting the connection portions with the bus electrodes 35B on the bus electrodes 35B. Others are the same as those of the solar battery cell of the third embodiment. The same symbols are assigned to the same parts.

  As a result, the positions where the current flows from the grid electrode 35G to the current collecting contact 26 via the bus electrode 35B are dispersed without being concentrated, so that current concentration can be prevented.

<Example>
Hereinafter, the measurement result of the photoelectric conversion characteristic of the photovoltaic cell manufactured based on the said embodiment is demonstrated as an Example. First, the solar battery cell used for the Example is demonstrated. FIG.1 (b) is sectional drawing which shows the structure of the photoelectric conversion cell used for the Example, ie, the photovoltaic cell 10. As shown in FIG. The dimensions of the n-type single crystal silicon substrate 1 were 125 mm in length, 125 mm in width, and 150 μm in height. Moreover, the length of the side of the corner part of four corners was 1.5 mm. In this embodiment, a heterojunction type single crystal silicon solar cell in which the pn junction and the passivation layer are made of amorphous silicon is used. However, a diffusion type single crystal silicon solar cell that forms a pn junction by thermal diffusion of impurities. Battery cells may be used.

  On one surface of the n-type single crystal silicon substrate 1, an i-type amorphous silicon layer 2i and a p-type amorphous silicon layer 2p were formed in this order using a chemical vapor deposition (CVD) method. On the other surface of the n-type single crystal silicon substrate 1, an i-type amorphous silicon layer 3i and an n-type amorphous silicon layer 3n were formed in this order by chemical vapor deposition.

Then, the translucent conductive film 4 was formed on the p-type amorphous silicon layer 2p and the n-type amorphous silicon layer 3n by sputtering or vapor deposition, respectively. The film thickness of the translucent conductive film 4 is desirably a film thickness at which the reflectance decreases at the peak wavelength of the sunlight spectrum due to the interference effect. Indium oxide (In ₂ O ₃ : Indium Oxide) was used as the light-transmitting conductive film material.

  Thus, after forming the translucent conductive film 4 on the p-type amorphous silicon layer 2p and the n-type amorphous silicon layer 3n, the current collecting electrode 5 was formed thereon.

  A method for forming the collector electrode 5 on the light receiving surface side by plating will be described below. A plating seed layer is formed on the light receiving surface side of the solar battery cell 10. A resist film is spin-coated on the seed layer, and an exposure and development process is performed to obtain a resist opening pattern. Here, a thick film resist having a high viscosity was applied, and an opening pattern having a cross-sectional shape having a thickness of 40 μm and a width of 30 μm was formed by adjusting the number of rotations of the substrate.

  Subsequently, the exposed portion of the plating seed layer is washed with dilute sulfuric acid, and then the substrate and the copper plate are immersed in a copper sulfate solution. A voltage is applied with the copper plate as the anode and the substrate side as the cathode. The layer is deposited to deposit the grid electrode 5G and the bus electrode 5B. Next, the resist is stripped using an organic alkaline stripping solution. Finally, the plating seed layer is etched. As the selective etching solution for the seed layer, for example, a mixed solution of phosphoric acid, nitric acid, and acetic acid is used if the seed layer is silver, and a mixed solution of nitric acid and hydrogen peroxide solution is used if the seed layer is a copper seed.

  The back electrode 6 may be formed using a screen printing method using Ag paste, or may be formed simultaneously by the same electroplating method as that on the light receiving surface 1A side.

  By carrying out the above steps, a solar battery cell 10 used in this example was obtained. FIG. 12 is a diagram showing a measurement result of energy conversion efficiency of the solar cell module manufactured based on Embodiment 1 as Example 1. FIG. In Example 1, the solar cell module 1 was created based on the first embodiment. Five types of modules of W = 0.1 mm, 0.3 mm, 1 mm, 2 mm, and 4 mm were prepared. A tab wire 20 having a width of 4 mm and a thickness of 0.05 mm was used. The lengths of the vertical tab lines 21a and 21d were 125.1 mm, 125.3 mm, 126.0 mm, 127.0 mm, and 129.0 mm according to the cell spacing W, respectively. The width and thickness of the vertical tab line 21d are the same as those of the vertical tab line 21a, and the five types of lengths are fixed at 125 mm. The tab wire 20 was cut out from a 0.05 mm thick copper sheet. The contact pallet 22 is also a copper isosceles right triangle, and two sides of equal length of 7 mm and a thickness of 0.1 mm are bonded to the corner portion 21c of the tab wire 20 by spot welding at a plurality of locations. The connection between the contact pallet 22 and the bus electrode 5B of the solar battery cell 10 was made by the copper conductive thin piece 24, the cell portion was bonded by soldering, and the current collecting portion was bonded by point welding. At this time, five types of solar cell modules 100 having different widths W of the blank regions V between the solar cells 10 in the module were produced, and the energy conversion efficiency was measured.

  As shown in FIG. 12, as the width W of the blank area is decreased, the short-circuit current density in the solar cell module 100 is increased, and the energy conversion efficiency of the solar cell module 100 is monotonously increased. By reducing the cell spacing W from 4 mm to 0.1 mm, the energy conversion of the solar cell module 100 increased by 2.3% from 17.6% to 19.9%. This is because the light reflection loss to the outside of the cell in the blank region V is reduced by reducing the area of the blank region.

  Moreover, as Example 2, the light receiving surface side grid electrode was formed by the screen printing method using Ag paste in the solar cell module 100 manufactured based on the first embodiment. Here, the width W of the blank area V was set to 0.1 mm. When the energy conversion efficiency of the solar cell module according to Example 2 was measured, it was 18.5%, which was 1.4% of the efficiency in Example 1 compared with the case where the width W of the blank region V was 0.1 mm. Declined. This is because, in the collector electrode formation on the light receiving surface 1A side using the screen printing method with Ag paste, the resistivity of Ag paste is about 8 times higher than that of bulk copper, so that the energy loss due to electrical resistance is large. . For this reason, it is desirable that the solar cell module 100 according to the present embodiment uses a material having a low resistivity for the light-receiving surface electrode by using a plating method.

  In principle, the width W of the blank region can be reduced to about 0.01 mm by using the present invention. However, when adjacent solar cells come into contact with each other, the p layer and the n layer of the solar cells Causes an electrical short circuit, resulting in a significant decrease in power generation output. For this reason, the width W of the blank area V is set such that at least a distance of about 0.1 mm is provided between the cells in order to prevent adjacent solar cells from contacting each other when the module is deformed. Is desirable.

  As described above, the solar cell module according to the present invention is useful for improving the energy conversion efficiency of the solar cell module.

  Note that a wafer formed by slicing an ingot after being pulled is often used as a single sheet without being divided into a plurality of pieces by dicing, and is almost rectangular. However, other shapes such as a triangle, a hexagon, and an octagon may be used. In the first to third embodiments, the description has been given of the solar cell formed using the silicon wafer formed by slicing the silicon ingot and having the four corners cut off. However, the rectangular solar cell having the four corners not cut off has been described. It is also applicable to. About the configuration of the collector electrode and the configuration of the inter-element connection in the solar cell module of the present embodiment, since the shadow loss is small and the photoelectric conversion efficiency is high, in this case, by devising the configuration of the inter-element connection, It is also possible to reduce the cell spacing of the solar battery cells.

  Moreover, in the said Embodiment 1-3, although the solar cell module 100 which connected the several photovoltaic cell with the tab wire 20 as an inter-element connection body was demonstrated, it is limited to the case where a several photovoltaic cell is connected. It is also possible to use a tab wire as a current extraction part when modularizing one solar battery cell.

  Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  1 n-type single crystal silicon substrate, 1A light-receiving surface, 1B back surface, 2i, 3i i-type amorphous silicon layer, 2pp p-type amorphous silicon layer, 3n n-type amorphous silicon layer, 4 translucent conductive film 5, 15, 25 Current collecting electrode, 5B, 15B, 25B Bus electrode, 5G, 15G, 25G Grid electrode, 6 Back electrode, 10 Solar cell, 10S1, 10S2 Solar cell in folded portion, 10n1 Sun in normal row Battery cell, 20 Tab wire, 20R Current extraction part, 21 Linear body, 21a, 21d Vertical tab line, 21b Horizontal tab line, 21c Corner part, 21e Intermediate connection part, 21f Tip connection part, 22 Contact pallet, 23 Insulating layer , 24 conductive flakes, 26 current collecting contact, O opening location, V blank area.

Claims (14)

A semiconductor substrate provided with a photoelectric conversion unit;
First and second electrodes respectively formed on opposite first and second main surfaces of the semiconductor substrate;
The first electrode arranged on the light-receiving surface side,
Bus electrodes provided at two continuous corners of the first main surface;
A solar cell having a grid electrode connected to the bus electrode;
The solar cell module which has an inter-element connection body connected to the said bus electrode, respectively.   The solar cell module according to claim 1, wherein the grid electrode extends radially from the two bus electrodes. The bus electrodes are provided at four corners of the first main surface,
The solar cell module according to claim 1, wherein the grid electrode extends radially toward the center of the first main surface. The bus electrode is four wedge-shaped bodies formed so as to gradually become thinner from the four corners of the first main surface toward the center of the first main surface,
The solar cell module according to claim 1, wherein the grid electrode extends concentrically so as to intersect the bus electrode. The solar cell has first and second solar cells,
The inter-element connector is
One end is connected to the bus electrode of the first solar cell, and the other end is connected to the second electrode provided on the second main surface of the second solar cell,
The solar cell module of any one of Claim 1 to 4. The inter-element connector is
A linear conductor having a first connection at one end and a second connection at the other end;
Connected to the bus electrode at the first connecting portion;
The solar cell module according to claim 5, wherein the second connection portion is connected to a second electrode provided on a second main surface of the solar cell. The inter-element connector is
A first conductor portion connected to the second main surface of the first solar cell via an insulating portion;
A second conductor portion connected to a second electrode provided on the second main surface of the second solar cell,
The first and second conductor portions are provided on the same plane and connected to each other;
The solar cell module according to claim 5, wherein the first conductor portion includes a contact pallet connected to the bus electrode and connected to the first conductor portion and extending to the first main surface.   The solar cell module according to claim 7, wherein the contact pallet includes a wedge-shaped conductive foil extending on the bus electrode at a tip. A semiconductor substrate provided with a photoelectric conversion unit;
First and second electrodes respectively formed on opposite first and second main surfaces of the semiconductor substrate;
The first electrode arranged on the light-receiving surface side,
Bus electrodes provided at two continuous corners of the first main surface;
A solar cell having a grid electrode connected to the bus electrode.   The solar cell according to claim 9, wherein the grid electrode extends radially from the two bus electrodes. The bus electrodes are provided at four corners of the first main surface,
The solar cell according to claim 9, wherein the grid electrode extends radially toward the center of the first main surface. The bus electrode is four wedge-shaped bodies formed so as to gradually become thinner from the four corners of the first main surface toward the center of the first main surface,
The solar cell according to claim 9, wherein the grid electrode extends concentrically so as to intersect the bus electrode. The first electrode of the first solar cell having the first electrode formed on the first main surface which is the light receiving surface and the second electrode formed on the second main surface opposite to the first main surface; ,
A second electrode of a second solar cell having a first electrode formed on a first main surface which is a light-receiving surface and a second electrode formed on a second main surface opposite to the first main surface; The
An inter-element connection body to be connected,
A first conductor portion connected to the second main surface of the first solar cell via an insulating portion;
A second conductor portion connected to a second electrode provided on the second main surface of the second solar cell,
The first and second conductor portions are provided on the same plane and connected to each other;
The first conductor portion is connected to the first conductor portion, extends to the first main surface, and includes a contact pallet connected to the first electrode,
An inter-element connection body in which the first conductor portion is provided corresponding to the first electrode.   The inter-element connection body according to claim 13, wherein the contact pallet includes a wedge-shaped conductive foil extending on the first electrode.

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