WO2019092885A1

WO2019092885A1 - Solar cell module

Info

Publication number: WO2019092885A1
Application number: PCT/JP2017/040758
Authority: WO
Inventors: 裕樹長谷川
Original assignee: 三菱電機株式会社
Priority date: 2017-11-13
Filing date: 2017-11-13
Publication date: 2019-05-16
Also published as: TW201919250A; JPWO2019092885A1; TWI680586B

Abstract

This solar cell module comprises a plurality of solar battery cells connected by means of tab lines (20) each comprising a round wire conductor as a base material and having a diameter which is the same as the width of light-receiving surface bus electrodes (12B), the tab lines (20) being connected to the light-receiving surface bus electrodes (12B) on a one-to-one basis. The tab lines (20) extend in a direction in which the solar battery cells are linked by means of the tab lines. The tab lines (20) are connected to an upper surface of the light-receiving surface bus electrodes (12B) of one solar battery cell of two solar battery cells adjacent to each other, and are connected to back-surface electrodes of the other solar battery cell. Under the condition that the solar battery cells have a square shape with each side having a length of not less than 150 mm and not more than 160 mm, the light-receiving surface has a sheet resistance in a range of not less than 70 Ω/sq. and not more than 90 Ω/sq., and grid electrodes have a resistance value of not less than 0.45 Ω/cm and not more than 0.7 Ω/cm, 10 or more and 15 or less light-receiving surface bus electrodes (12B) having a width of 0.4 mm are arranged side by side, or five or more and 15 or less light-receiving surface bus electrodes (12B) having a width of 0.5 mm are arranged side by side.

Description

Solar cell module

The present invention relates to a solar cell module that converts light energy into electrical energy.

A solar battery cell having an impurity diffusion layer uses, for example, a p-type silicon substrate as a base material, and a concavo-convex shape for enhancing the light collection ratio is formed on the light receiving surface side of the p-type silicon substrate. An antireflective film made of a silicon nitride film is formed. Further, as a light receiving surface side collecting electrode for collecting electrons photoelectrically converted in the solar battery cell, a grid electrode and a bus electrode are formed on the antireflection film.

On the other hand, on the back surface side of the p-type silicon substrate, a back surface current collection electrode and a back surface contact electrode are often formed as a back surface side current collection electrode. The back surface current collection electrode is provided to form a back surface field (BSF) for improving open circuit voltage and short circuit current, and to collect current on the back surface side. The back surface contact electrode is provided in order to take out the holes collected by the back surface current collection electrode to the outside and to make contact with the external electrode.

In such a solar battery cell, a wiring material called a tab wire is connected to each of the bus electrode and the back surface contact electrode in order to take out the power generated by photoelectric conversion to the outside. However, one solar battery cell generates a small amount of power. For this reason, a plurality of solar cells are electrically connected in series or in series and parallel to form a solar cell module. In a solar cell module, electrodes of different polarities in adjacent solar cells are electrically connected alternately by tab lines.

Patent Document 1 discloses a solar cell module in which a plurality of solar cell elements electrically connected to each other by inner leads are disposed between the light transmitting panel and the back surface protective material. The solar cell element has a light receiving surface electrode including three surface bus bar electrodes for output extraction and a plurality of surface finger electrodes orthogonal to the surface bus bar electrodes on the light receiving surface side of the semiconductor substrate. Three back bus bar electrodes are provided on the non-light receiving surface side of the semiconductor substrate.

Patent No. 4953562

In recent years, in the solar cell module, as the current of the solar cell increases, so-called shadow loss increases as a loss of power generation efficiency, which is a loss of power generation efficiency due to the shadow of the tab wire and the bus electrode, The problem is that the amount of However, in the patent document 1, such a problem is not considered and can not be solved.

This invention is made in view of the above, Comprising: It aims at obtaining the solar cell module which can suppress the fall of the output resulting from the tab wire and bus electrode which connect a several photovoltaic cell.

In order to solve the problems described above and to achieve the object, the solar cell module according to the present invention is electrically connected by a tab wire between the light-receiving side protection component and the back-side protection component having translucency The plurality of solar cells are arranged. The solar battery cell includes a semiconductor substrate having a pn junction, a plurality of grid electrodes extending in parallel with a direction orthogonal to the connection direction of the solar cells by the tab line on the light receiving surface of the semiconductor substrate, and a plurality of grid electrodes on the light receiving surface. A light receiving surface electrode having a plurality of light receiving surface bus electrodes connected and extending along a connecting direction, and a back surface electrode extending along the connecting direction on the back surface of the semiconductor substrate facing the opposite side to the light receiving surface. The tab wire has a round conductor as a base material and has the same diameter as the width of the light receiving surface bus electrode. One tab line is connected to one light receiving surface bus electrode. The tab wire is provided in the same number as the light receiving surface bus electrode, extends along the connection direction, and is connected to the upper surface of the light receiving surface bus electrode of one of the two adjacent solar battery cells, Connected to the back electrode of the solar cell. The solar battery cell has a square shape in which the length of one side is in the range of 150 mm or more and 160 mm or less, and the sheet resistance of the light receiving surface is 70 Ω / sq. 90 Ω / sq. A range of 10 to 15 light-receiving surface bus electrodes having a width of 0.4 mm under the following range, and under the condition that the resistance value of the grid electrode is 0.45 Ω / cm or more and 0.7 Ω / cm or less Or light receiving surface bus electrodes having a width of 0.5 mm are provided in a range of 5 or more and 15 or less.

ADVANTAGE OF THE INVENTION The solar cell module concerning this invention has an effect that the fall of the output resulting from the tab wire and bus electrode which connect a several photovoltaic cell can be suppressed.

The perspective view which looked at the solar cell module concerning Embodiment 1 of this invention from the light-receiving surface side The disassembled perspective view which looked at the solar cell module concerning Embodiment 1 of this invention from the light-receiving surface side Principal part sectional view of solar cell module according to Embodiment 1 of the present invention The perspective view which looked at the solar cell array concerning Embodiment 1 of the present invention from the back side The principal part perspective view which looked at the solar cell string concerning Embodiment 1 of this invention from the light-receiving surface side The perspective view of the principal part which looked at the solar cell string concerning Embodiment 1 of the present invention from the back side. The top view which looked at the photovoltaic cell concerning Embodiment 1 of this invention from the light-receiving surface side The top view which looked at the photovoltaic cell concerning Embodiment 1 of this invention from the back surface side which turns to the light receiving surface side and the opposite side It is an exploded perspective view explaining the connection with the photovoltaic cell and tab wire in the solar cell module concerning Embodiment 1 of this invention, and the disassembled perspective view seen from the light-receiving surface side It is an exploded perspective view explaining the connection with the photovoltaic cell and tab wire in the solar cell module concerning Embodiment 1 of this invention, and the disassembled perspective view seen from the back surface side The flowchart which shows the procedure of the manufacturing method of the solar cell module which depends on the form 1 of execution of this invention Schematic diagram showing a tab wire bonding step of electrically bonding the light receiving surface electrode and the back surface electrode to the tab wire according to the first embodiment of the present invention Principal part sectional view schematically showing the periphery of the tab wire in the solar cell module according to Embodiment 1 of the present invention Principal cross-sectional view schematically showing the periphery of a tab wire in a solar cell module using a rectangular tab wire A diagram showing the types of tab lines and number of tab lines of solar cells for which characteristics were simulated, and shadow loss at the tab lines Characteristic diagram that graphed Figure 15 The figure which shows the type of tab wire of the solar cell module and the number of tab wires which simulated the characteristic, and the fill factor which is the index of the output of the solar cell module Characteristic diagram which made FIG. 17 graph Diagram showing the power loss that occurs when making a solar cell module from solar cells Characteristic diagram which made FIG. 19 graph

Below, the solar cell module concerning Embodiment 1 of this invention is demonstrated in detail based on drawing. The present invention is not limited by the first embodiment. Further, in the drawings shown below, the scale of each member may be different from the actual one for easy understanding. The same applies to each drawing.

Embodiment 1
FIG. 1 is a perspective view of a solar cell module 100 according to a first embodiment of the present invention as viewed from a light receiving surface side. FIG. 2 is an exploded perspective view of the solar cell module 100 according to the first embodiment of the present invention as viewed from the light receiving surface side. FIG. 3 is a cross-sectional view of main parts of the solar cell module 100 according to the first embodiment of the present invention. FIG. 4 is a perspective view of the solar cell array 70 according to the first embodiment of the present invention as viewed from the back side. FIG. 5 is a perspective view of an essential part of the solar cell string 50 according to the first embodiment of the present invention as viewed from the light receiving surface side. FIG. 6 is a perspective view of an essential part of the solar cell string 50 according to the first embodiment of the present invention as viewed from the back side. FIG. 7 is a plan view of the solar battery cell 10 according to the first embodiment of the present invention as viewed from the light receiving surface side. FIG. 8 is a plan view of the solar battery cell 10 according to the first embodiment of the present invention as viewed from the back surface side facing away from the light receiving surface side. In FIG. 8, an example of the joining position of the tab wire 20 is indicated by a broken line.

In the solar cell module 100 according to the first embodiment, as shown in FIGS. 1 to 3, the light receiving surface side of the solar cell array 70 is covered with the light receiving surface side sealing member 33 and the light receiving surface protection component 31. The back surface side of the array 70 facing the opposite side to the light receiving surface is covered with the back surface side sealing material 34 and the back surface protection component 32, and the outer peripheral edge is surrounded by the reinforcing frame 40.

As shown in FIG. 4, the solar cell array 70 is configured such that a plurality of solar cell strings 50 are electrically and mechanically connected in series or in parallel by a horizontal tab line 25 and an output tab line for collecting collected power. It is done. The solar cell array 70 outputs power from the output tab line to the external interface via the terminal box 41.

As shown in FIG. 3 to FIG. 6, the solar cell string 50 is configured by connecting a plurality of solar cells 10 in a rectangular shape arranged adjacent to each other in series electrically and mechanically at the tab wire 20. ing. As shown in FIGS. 3 to 6, the plurality of solar cells 10 are connected in series in the X direction, which is the first direction, by the tab wires 20. The first direction is the connection direction of the plurality of solar cells 10 connected by the tab wire 20.

The solar battery cell 10 has a light receiving surface of a semiconductor substrate which is a first main surface of the semiconductor substrate 11 having a rectangular shape and formed of a p-type single crystal silicon substrate having an n-type impurity diffusion layer formed and a pn junction formed. On the 11A side, in order to increase the light collection rate, a concavo-convex shape is formed by texture etching. Here, the outer shape of the semiconductor substrate 11 has a square shape in the surface direction of the semiconductor substrate 11. The n-type impurity diffusion layer is formed on the light receiving surface 11A side of the semiconductor substrate. Then, a silicon nitride film, which is an antireflective film, is formed on the light receiving surface 11A of the semiconductor substrate. In the drawings, the uneven shape and the antireflective film are not shown. In the solar battery cell 10, the light receiving surface electrode 12 is formed on the light receiving surface 11A side of the semiconductor substrate, and the back surface electrode 13 is formed on the back surface 11B side of the semiconductor substrate which is the second main surface of the semiconductor substrate 11.

In the case of a single crystal silicon solar cell, the solar battery cell 10 has a square shape with a side length of about 150 mm or more and about 160 mm or less, and in the first embodiment, the side length is 156 mm. The semiconductor substrate 11 is not limited to a p-type single crystal silicon substrate, and an n-type single crystal silicon, a polycrystalline silicon substrate, or the like is also applicable.

In the first embodiment, the sheet resistance of the n-type impurity diffusion layer, which is the sheet resistance of the light receiving surface, is 70 Ω / sq. 90 Ω / sq. The following n-type impurity diffusion layers are formed in the surface layer of the semiconductor substrate 11.

On the light receiving surface 10A side of the solar battery cell which is the first surface of the solar battery cell 10, as shown in FIGS. 5 and 7, it is a grid electrode of a light receiving surface collecting electrode for collecting electrons generated by light-electron conversion. A plurality of light receiving surface grid electrodes 12G and light receiving surface bus electrodes 12B which are bus electrodes of light receiving surface bonding electrodes for collecting the electrons collected by the light receiving surface grid electrodes 12G and bonding the tab wires 20 are formed. The width of the light receiving surface bus electrode 12B is thinned to the same width as the width of a tab line 20 described later. The width of the light receiving surface bus electrode 12B is the same as the width of the tab wire 20, and the tab wire 20 is connected to the correct position on the light receiving surface bus electrode 12B, whereby the tab wire 20 protrudes from the light receiving surface bus electrode 12B. It is possible to reduce shadow loss caused by The light receiving surface grid electrode 12G is an electrode for collecting a photocurrent, and in order to collect the photocurrent while preventing the sunlight from reaching the inside of the solar battery cell 10, a plurality of thin linear electrodes are provided. This book is formed in parallel.

Further, as shown in FIG. 7, the light receiving surface bus electrodes 12B are provided in six lines in a line along substantially the entire length of the solar cell 10 along the first direction which is the connecting direction of the solar cell 10. ing. That is, the light receiving surface bus electrodes 12B are provided in connection with all the light receiving surface grid electrodes 12G along the direction orthogonal to the light receiving surface grid electrode 12G. For convenience, FIGS. 1 and 2 show the case where the light receiving surface bus electrodes 12B are provided in two rows. The light receiving surface bus electrode 12 </ b> B is an electrode provided to electrically bond with the tab wire 20. The light receiving surface bus electrode 12B and the light receiving surface grid electrode 12G are formed by applying and baking a conductive paste having metal particles in a desired range.

On the back surface 10B side of the solar battery cell which is the second main surface of the solar battery cell 10, as shown in FIGS. 6 and 8, a back surface junction including a back surface current collecting electrode 13a containing aluminum (Al) and silver (Ag) An electrode 13 b is formed to constitute a back electrode 13. The back surface current collection electrode 13a is an electrode provided to form a back surface field layer (BSF) (not shown) for improving the open circuit voltage and the short circuit current, and to collect current on the back surface side. Cover almost the entire area of 10B.

Further, the back surface bonding electrode 13b is an electrode provided for taking out the holes collected by the back surface current collecting electrode 13a to the outside and making a contact with the external electrode. That is, the back surface bonding electrode 13 b is an electrode provided for electrically bonding to the tab wire 20. The back surface contact electrode 13 b is provided along the first direction, which is the connection direction of the solar cells 10, in the same manner as the light receiving surface bus electrode 12 B. The back surface bonding electrode 13 b is disposed at a position facing the light receiving surface bus electrode 12 B with the semiconductor substrate 11 interposed therebetween.

As shown in FIG. 8, the back surface contact electrodes 13 b according to the first embodiment are arranged in six rows in the shape of a stepping stone along substantially the entire length of the solar battery cell 10 along the first direction which is the connection direction of the solar battery cells 10. Provided in The back surface current collection electrode 13a and the back surface junction electrode 13b are formed by apply | coating and baking the conductive paste which has metal particles, such as Al or Ag, as mentioned above in a desired range.

FIG. 9 is an exploded perspective view for explaining the connection between the solar cell 10 and the tab wire 20 in the solar cell module 100 according to the first embodiment of the present invention, and is an exploded perspective view seen from the light receiving surface side. FIG. 10 is an exploded perspective view for explaining the connection between the solar cell 10 and the tab wire 20 in the solar cell module 100 according to the first embodiment of the present invention, and is an exploded perspective view seen from the back side.

As shown in FIG. 5, FIG. 6, FIG. 9, and FIG. 10, in the solar cell string 50, the light receiving surface 10A of the solar cell in one solar cell 10 of two adjacent solar cells 10 is adjacent The back surface 10 </ b> B of the other solar cell among the two solar cells 10 to be matched is alternately connected by six tab lines 20. In the tab wire 20, the back surface side connection region 23b is soldered to the back surface bonding electrode 13b formed on the back surface 10B of the solar battery cell, and the light receiving surface is formed on the light receiving surface 10A of the solar battery cell in the adjacent solar battery cell 10. The light receiving surface side connection area 23a is soldered to the bus electrode 12B. That is, the tab line 20 connected to the light receiving surface bus electrode 12B formed on the light receiving surface 10A of the solar battery cell 10 in the solar battery cell 10 is formed on the back surface 10B of the solar battery cell in the adjacent solar battery cell 10 The plurality of solar cells 10 are connected in series by being connected to the back surface contact electrode 13 b.

The back surface bonding electrode 13 b is disposed at a position facing the light receiving surface bus electrode 12 B with the semiconductor substrate 11 interposed therebetween. Therefore, in one solar battery cell 10, the back surface side connection region 23b of the tab wire 20 bonded to the back surface bonding electrode 13b and the light receiving surface side connection region 23a of the tab wire 20 bonded to the light receiving surface bus electrode 12B are However, at least a part of the regions is disposed opposite to each other.

The tab wire 20 is between the light receiving surface side connection region 23 a and the back surface side connection region 23 b in order to connect the light receiving surface bus electrode 12 B of the solar battery cell 10 and the back surface bonding electrode 13 b of the adjacent solar battery cell 10. And an inter-cell region 24 which is a bend. The tab lines 20 used in the solar cell string 50 all have the same total length, that is, the total length of the light receiving surface side connection region 23a, the back surface side connection region 23b, and the inter-cell region 24. .

The tab wire 20 as a wiring material for connecting the solar battery cells 10 to each other is made of a conductor having a round cross section, and is made of a round wire of a metal material of good conductor such as copper. Solder is coated on the surface of the tab wire 20. Details of the tab line 20 according to the first embodiment will be described later. In addition, for convenience, in FIG. 1 and FIG. 2, a state in which two adjacent solar battery cells 10 are connected by two tab lines 20 is shown.

The back surface side sealing material 34 disposed on the back surface 10B side of the solar battery cell of the solar cell array 70 and the light receiving surface side sealing material 33 disposed on the light reception surface 10A side of the solar battery cell Material having conductivity, electrical insulation, and flexibility is used, and a thermoplastic synthetic resin mainly composed of a thermoplastic resin such as ethylene vinyl acetate (EVA) or polyvinyl butyral (PVB) Materials are preferred.

As the light receiving surface protection component 31, a material having light transmission and excellent in moisture resistance, weather resistance, hydrolysis resistance, and insulation is used, and in addition to a highly rigid light transmission substrate such as a glass substrate, Resin materials, such as a fluorine resin sheet and a polyethylene terephthalate (Polyethylene Terephthalate: PET) sheet, are used.

As the back surface protection component 32, a material excellent in moisture resistance, weather resistance, hydrolysis resistance and insulation is used, and a resin material such as a fluorine resin sheet or a polyethylene terephthalate (PET) sheet on which alumina or silica is vapor deposited The back sheet or back film is used.

Below, the manufacturing method of the solar cell module 100 concerning this Embodiment 1 is demonstrated. FIG. 11 is a flowchart showing the procedure of the method of manufacturing the solar cell module 100 according to the first embodiment of the present invention.

First, in step S10, a solar battery cell 10 is formed. A p-type single crystal silicon substrate is used as a starting material, and in order to increase the light collection rate, a concavo-convex shape is formed by texture etching on the surface to be the light receiving surface. Then, an n-type impurity diffusion layer (not shown) is formed on the light receiving surface side of the p-type single crystal silicon substrate by diffusion to form a pn junction. The sheet resistance of the n-type impurity diffusion layer, which is the sheet resistance of the light receiving surface, is 70 Ω / sq. 90 Ω / sq. It will be about the following. Further, a silicon nitride film as an antireflective film is formed on the n-type impurity diffusion layer.

Next, as shown in FIG. 7, the light receiving surface electrode 12 composed of the light receiving surface bus electrode 12B and the light receiving surface grid electrode 12G is formed on the light receiving surface 10A of the solar battery cell by screen printing and firing. In addition, the formation method of the light-receiving surface electrode 12 is not limited to screen printing and baking. Further, as shown in FIG. 8, on the back surface 10B of the solar battery cell, a back surface current collecting electrode 13a and a back surface bonding electrode 13b are formed by screen printing and firing. In addition, the formation method of the photovoltaic cell 10 mentioned above is not limited, It can carry out by a well-known technique. Here, the width of the light-receiving surface bus electrode 12B is formed to be the same as the width of the tab line 20 which is a round line. By connecting the tab line 20 to the correct position on the light receiving surface bus electrode 12B with the width of the light receiving surface bus electrode 12B being the same width as the width of the tab wire 20, the tab line 20 protrudes from the light receiving surface bus electrode 12B. Shadow loss caused can be reduced.

Next, the tab wire 20 is connected to the photovoltaic cell 10 in step S20. That is, the back surface side connection region 23b of the tab wire 20 is disposed on the back surface bonding electrode 13b formed on the back surface 10B of the solar battery cell, and is formed on the light receiving surface 10A of the solar battery cell in the adjacent solar battery cell 10. The light receiving surface side connection area 23a of the tab line 20 is disposed on the light receiving surface bus electrode 12B. Then, the solder coated on the tab wire 20 is melted by heating and then solidified. Thereby, solder bonding is performed between the back surface bonding electrode 13b and the back surface side connection region 23b, and the light receiving surface bus electrode 12B and the light receiving surface side connection region 23a, and the tab wire 20 electrically and mechanically Connected

FIG. 12 is a schematic view showing a tab wire bonding step of electrically bonding the light receiving surface electrode 12 and the back surface electrode 13 to the tab wire 20 according to the first embodiment of the present invention. In the tab wire bonding step, as shown in FIG. 12, the back surface side connection region 23b of the tab wire 20 is overlapped on the back surface bonding electrode 13b of the solar battery cell 10, and the light receiving surface bus electrode 12B of the adjacent solar battery cell 10 not shown The light receiving surface side connection area 23 a of the line 20 is overlapped. Then, by heating the tab wire 20 with the heat tool 200, electrical connection and mechanical connection between the tab wire 20 and the back surface bonding electrode 13b, and electrical connection and machine between the tab wire 20 and the light receiving surface bus electrode 12B. Connection can be obtained simultaneously. Specifically, by heating the tab wire 20 by the heat tool 200, the solder coated on the surface of the tab wire 20 is melted. Thereafter, the tab wire 20 is cooled to solidify the solder, and the tab wire 20 and the light receiving surface bus electrode 12B are soldered via the solder, and the tab wire 20 and the back surface bonding electrode 13b are soldered via the solder. It is joined.

The tab wire 20 may be bonded to the solar cell 10 by another method such as thermocompression bonding or ultrasonic welding. In the tab wire bonding step, the bonding step of the tab wire 20 on the back surface side and the bonding step of the tab wire 20 on the light receiving surface side may be divided into two steps.

And the connection process of the above tab wire 20 is repeated, and several solar cell strings 50 in which the desired number of solar cells 10 were connected in series are formed. Then, the solar cell array 70 is formed by connecting the plurality of solar cell strings 50 obtained as described above with the horizontal tab lines 25. The solar cell array 70 is formed by connecting a plurality of solar cell strings 50 arranged in parallel in series using the bus bar as the horizontal tab line 25 and installing the bus bar as an output tab line for extracting power. .

Next, in step S30, the light receiving surface sealing material 33 and the light receiving surface protection component 31 are disposed on the light receiving surface side of the solar cell array 70 in the arrangement shown in FIG. The back side sealing material 34 and the back side protection component 32 are disposed to form a laminate.

Next, in step S40, the laminate is mounted on a laminating apparatus, and heat treatment and lamination treatment are performed for about 30 minutes, for example, at a temperature of 140 ° C. or more and 160 ° C. or less. By the lamination process, the solar cell array 70 and the light receiving surface protection component 31 are bonded by the light receiving surface side sealing material 33, and the solar cell array 70 and the back surface protective component 32 are bonded by the back surface side sealing material 34. Thereby, the component part of a laminated body is integrated and the solar cell module 100 is obtained.

In the above description, the back junction electrode 13b is provided in the shape of a stepping stone along the first direction over substantially the entire length of the solar cell 10, but the back junction electrode 13b is in the first direction. Along the entire length of the solar cell 10 may be provided continuously in the form of a strip or line.

Next, the tab line 20 according to the first embodiment will be described. FIG. 13 is a cross-sectional view of relevant parts schematically illustrating the periphery of the tab wire 20 in the solar cell module 100 according to the first embodiment of the present invention. FIG. 14 is a cross-sectional view of main parts schematically showing the periphery of the tab wire in the solar cell module using the rectangular tab wire. Arrows in FIG. 13 and FIG. 14 indicate the optical path of sunlight incident on the solar battery cell.

The tab wire 20 extends in the connecting direction of the solar cells 10, that is, the first direction when connected to the solar cells 10, and the light receiving of one of the two adjacent solar cells 10 is received. While being connected with the upper surface of the surface bus electrode 12B, it is connected with the upper surface of the back surface contact electrode 13b which is the back surface electrode of the other solar cell 10. In the tab wire 20, a round wire of a good conductor represented by a metal material such as copper is used as a base material, and a solder is coated on the surface of the round wire. In the present embodiment, the tab wire 20 is plated with solder on the surface of the copper round wire conductor 20a, and a thin layer 20b of solder is formed on the entire surface of the round wire conductor 20a. Coating of the solder on the tab wire 20 is preferably performed by plating. By plating the solder on the surface of the tab wire 20, the solder can be coated on the surface of the tab wire 20 reliably and uniformly.

In this case, the width of the light-receiving surface bus electrode 12B is the same as the diameter φ of the tab wire or smaller than the width of the tab wire 20, twice the thickness m of the thin layer of solder and the diameter of the round conductor The total dimension of φa and. However, the thickness m of the thin layer of solder is very thin compared to the diameter φa of the round conductor and is a negligible level.

In FIG. 14, the flat tab wire 300 having a flat shape is solder-plated on the surface of a flat conductor 300 a made of copper, and a thin layer 300 b of solder is formed on the entire surface of the flat conductor 300 a. The width of the light receiving surface bus electrode 12B is the same as the width w of the flat tab wire, and is the total size of twice the thickness m of the thin solder layer and the width wa of the flat conductor. . The thickness of the rectangular conductor 300a is represented by the thickness t of the rectangular conductor. However, the thickness m of the thin layer of solder is very thin compared to the width wa of the flat conductor and can be ignored.

The effects of the solar cell module 100 according to the first embodiment will be described below with reference to FIGS. 13 and 14. First, the first effect of using the round tab wire 20 will be described. It is generally known that the resistive loss at the tab wire depends on the cross-sectional area of the base material of the tab wire. Therefore, in the solar cell module 100 shown in FIG. 13, the resistance loss at the tab wire 20 depends on the cross-sectional area of the copper round wire conductor 20 a. Moreover, in the solar cell module shown in FIG. 14 using a rectangular tab wire, the resistance loss at the rectangular tab wire 300 depends on the cross-sectional area of the copper rectangular conductor 300a. Hereinafter, calculation of the cross-sectional area of the tab line 20 shown in FIG. 13 and the cross-sectional area of the flat tab line 300 shown in FIG. 14 will be described.

(Cross section of round wire conductor 20a)
Under the condition of the diameter φa = 0.5 mm of the round wire conductor, ie, the condition of the radius r = 0.25 mm of the round wire conductor, the cross sectional area S1 = πr ² = 0.296 mm ² of the round wire conductor.

(Cross section of flat conductor 300a)
Under the condition of the width wa of the flat conductor of 0.8 mm and the thickness t of the flat conductor of 0.25 mm, the cross sectional area S2 of the flat conductor is S2 = W × t = 0.2 mm ² .

Therefore, from the above calculation, under the above conditions, the resistance losses of the round conductor 20a and the flat conductor 300a are at the same level, and the resistance losses of the tab wire 20 and the flat tab 300 are at the same level.

Here, the light receiving surface coverage, which is the ratio of the tab line covering the light receiving surface of the solar battery cell, will be considered. The diameter φa = 0.5 mm of the round wire conductor is smaller than the width wa = 0.8 mm of the flat conductor. Therefore, the solar cell module 100 using the tab wire 20 has a light receiving surface in each solar cell as compared with a solar cell module using the same number of flat tab wires 300 having the same level of resistance loss as the tab wire 20. The coverage can be reduced. Therefore, the solar cell module 100 suppresses the light receiving surface coverage of the solar battery cell 10 compared to the solar cell module using the same number of flat tab wires 300 having the same level of resistance loss as the tab wires 20, and generates power. The current can be increased to improve the output.

When the light receiving surface coverage is the same, the diameter φ of the tab wire 20 of the tab wire 20 can be enlarged to easily enlarge the cross-sectional area, the resistance loss of the tab wire 20 can be reduced, and the output can be improved. .

Below, the 2nd effect of using the tab line 20 of a round line is demonstrated. Under the above conditions, the resistance loss of the tab wire 20 and that of the flat tab wire 300 are equal, while the light blocking loss due to the shadow of the tab wire, that is, the so-called shadow loss is different. Under the condition that the tab wire 20 and the flat tab wire 300 having the same level of resistance loss as the tab wire 20 on the light receiving surface of the solar cell have the same length, the shadow loss due to one tab wire is tabbed Considering the width of the line shadow, the shadow loss L1 due to one tab line 20 is 0.5 mm. The shadow loss L2 by one flat rectangular tab line 300 is 0.8 mm. The thickness m of the thin layer of solder in the tab wire 20 and the flat tab wire 300 is ignored here because it is very thin.

Therefore, under the above conditions, the solar cell module 100 using the tab wire 20 can reduce the shadow loss as compared to a solar cell module using the same number of flat tab wires 300 as the tab wire 20. Therefore, the solar cell module 100 reduces the shadow loss and increases the generated current as compared with the solar cell module using the same number of flat tab wires 300 having the same level of resistance loss as the tab wires 20, Output can be improved.

Next, the third effect of using the round tab wire 20 will be described. In the solar cell module 100, since the cross-sectional shape of the tab wire 20 is circular, the sunlight hitting the tab wire 20 becomes reflected light that is reflected in various directions, and the reflected light enters the solar battery cell 10 It contributes to the improvement of photoelectric conversion efficiency. That is, in the solar cell module 100, since the tab wire 20 is a round wire, it diffusely reflects on the surface on the light receiving surface protection component 31 side of the tab wire 20, and the surface on the solar battery cell 10 side of the light reception surface protective component 31 The light amount of the reflected light RL incident on the inner surface 31a with an incident angle is increased. The reflected light RL is diffusely reflected by the inner surface 31 a of the light receiving surface protection component 31 and enters the solar battery cell 10.

Under the above conditions, the solar cell module 100 using the tab wire 20 has the same number of flat tab wires 300 as the tab wires 20 due to the increase of the diffuse reflection on the inner surface 31a of the light receiving surface protection component 31 as described above. Compared to the solar cell module used, an increase effect of light uptake into the solar cell 10 can be expected to be about 25%. However, depending on the shape of the round wire of the tab wire 20, the effect of increasing the light uptake into the solar battery cell 10 changes.

Next, the fourth effect of using the round tab wire 20 will be described. The flat tab wire 300 needs a rolling process such as round wire crushing to process a commercially available round wire into a flat angle when producing the flat conductor 300a which is a flat copper wire. Moreover, when using metal foil for a tab wire, the further rolling process is needed. On the other hand, in the tab wire 20, such a rolling process is unnecessary, and the processing cost at the time of manufacturing the tab wire 20 can be reduced. In addition to this, the round wire shape of the round wire conductor 20a of the tab wire 20 can be easily processed into any desired thickness by changing the diameter of the die when producing the round wire conductor 20a by die wire drawing. . Furthermore, since the tab wire 20 has a round wire shape, high speed random winding on the tab bobbin around which the tab wire is wound can be performed, and the manufacturing process of the tab wire can be simplified and the time can be shortened. Cost can be reduced.

In the solar cell module 100, by using the tab wire 20, the output can be improved while the manufacturing cost is reduced by the first to fourth effects described above.

When the tab wire is bonded to the light receiving surface bus electrode 12B by a method using no solder, such as thermocompression bonding or ultrasonic welding, only the round conductor 20a can be used as the tab wire 20. In this case, the width of the light receiving surface bus electrode 12B is the same as the diameter of the tab line 20, and is the diameter of the round conductor 20a. Further, since the resistance loss at the tab wire depends on the cross-sectional area of the copper material of the base material, the above calculation also holds in this case.

Next, when the number of tab lines is changed, the influence of the number of tab lines on the output of the solar battery cell and the solar cell module is determined by the solar cell module 100 using the tab line 20 and the tab line 20. It demonstrates based on the result of having simulated the characteristic about the solar cell module which has the same structure as the solar cell module 100 except having used said flat tab wire 300 instead.

The simulation of the characteristics of the solar cell and the solar cell module was performed on the solar cell module in which the types of tab lines and the number of tab lines were changed in the configuration of the solar cell module 100 according to the first embodiment described above. As shown in FIG. 4, the solar battery array 70 is configured such that 40 solar battery cells 10 are electrically connected in series. The solar battery cell 10 was a 156 mm square solar battery cell with a thickness of 200 μm. The sheet resistance of the n-type impurity diffusion layer, which is the sheet resistance of the light receiving surface, is 80 Ω / sq. And The number of light receiving surface grid electrodes was 100, and the resistance of the light receiving surface grid electrode 12G was 0.6 Ω / cm. The light receiving surface protection component 31 was a glass substrate, the light receiving surface side sealing material 33 and the back surface side sealing material 34 were EVA, and the back surface protection component 32 was a back film made of a PET sheet.

(Simulation of shadow loss)
FIG. 15 is a diagram showing the types of tab lines and the number of tab lines of the solar battery cell whose characteristics have been simulated, and the shadow loss (amperes: A) at the tab lines. The shadow loss indicates a reduction value of the short circuit current Isc (A) due to the tab wire. The short circuit current Isc (A) due to the tab wire is a short circuit current value of the solar battery cell reduced by forming the tab wire and the light receiving surface bus electrode. FIG. 16 is a characteristic graph of FIG.

In FIG. 15 and FIG. 16, a round wire 0.3 mmφa is a round wire tab wire having a diameter φa of 0.3 mm, and a round wire 0.4 mmφa is a round wire tab having a diameter φa of 0.4 mm As for the wire, a round wire 0.5 mmφa indicates a round wire tab wire having a diameter φa of the round wire conductor of 0.5 mm. Flat angle 0.5wa × 0.25t is a flat tab wire whose width wa of flat conductor is 0.5 mm and thickness t of flat conductor is 0.25 mm, and flat block 0.8wa × 0.25 t is width wa of flat conductor. The flat tab wire which is 0.8 mm and thickness t of a flat conductor is 0.25 mm is shown.

The thickness of the solder plating is neglected here because the thickness of the solder plating is very thin compared to the diameter φa of the round conductor or the width wa of the flat conductor and the influence of the solder plating on the shadow loss is small.

It can be seen from FIGS. 15 and 16 that as the number of tab lines increases, the shadow loss at the tab lines increases substantially in proportion to the number of tab lines. Among the samples of the solar cells for which the simulation was performed, in the solar cells using the flat tab wire, the increase in the shadow loss was noticeable because the light receiving surface coverage was large. Further, in FIGS. 15 and 16, when the case of the round wire 0.5 mmφa and the case of the flat angle 0.8wa × 0.25t at the same level of resistance loss are compared, the shadow in the case of the round wire 0.5 mmφa It can be seen that the loss is about half of the shadow loss when the angle is 0.8 wa × 0.25 t.

As the shadow loss increases, the light receiving surface coverage increases and the power generation area of the solar battery cell decreases, and as a result, the absolute amount of electrons that can be extracted from the solar battery cell decreases, and the short circuit current value decreases. . Then, as the solar battery cell is increased in current, the reduction amount of the short circuit current value increases even if the light receiving surface coverage is the same. By using the round wire tab wire, the shadow loss in each solar battery cell can be suppressed, so the shadow loss of the entire solar battery module can be suppressed, the decrease in output can be suppressed, and high output can be realized.

(Simulation of fill factor)
FIG. 17 shows the types of tab lines and the number of tab lines of the solar cell module whose characteristics were simulated, and the fill factor (F.F., curve factor) that is an index of the output of the solar cell module. FIG. FIG. 18 is a characteristic graph of FIG.

It can be seen from FIG. 18 that as the number of tab lines increases, the fill factor increases while drawing a parabola. One light receiving surface bus electrode 12B corresponds to one tab line, and when the number of tab lines increases, the number of light receiving surface bus electrodes 12B also increases. As the number of tab lines increases, the effective current transfer distance from the light receiving surface grid electrode 12G, which is a thin wire having a large electrical resistance, to the light receiving surface bus electrode 12B becomes short, so the resistance at the light receiving surface grid electrode 12G is reduced. The loss is reduced, and the resistance loss at the time of extracting the current from the solar battery cell is reduced, so that it is possible to reduce the current collection loss and achieve the high photoelectric conversion efficiency of the solar battery module. This high photoelectric conversion efficiency is common to both solar cell modules using round wire tab wires and solar cell modules using flat tab wires. Also, as the cross-sectional area of the tab wire is larger, the resistance loss at the tab wire is reduced and the fill factor is increased.

(Simulation of CTM (Cell to Module) loss)
FIG. 19 is a diagram showing an output loss generated when producing a solar cell module from solar cells. In FIG. 19, the tendency of the characteristics shown in FIG. 15 to FIG. 18 and the third effect of the above-mentioned round tab wire 20 which is an optical gain when using a round tab wire is taken into consideration, The power loss (%) generated when producing a solar cell module from a battery cell is shown together with the power ratio (%). In FIG. 19, the output loss (%) is indicated by a number in parentheses.

The output ratio is the short circuit current Isc of the solar cell module F.F. F. The short circuit current Isc of the solar cell module when assuming that there is no output loss that occurs when manufacturing the solar cell module from the solar cells with a value multiplied by. F. The ratio (%) to the value multiplied by. The short-circuit current Isc of the solar cell module F. F. The value obtained by multiplying the current value can know the current level at the maximum power output at which the solar cell module generates the maximum power, assuming that the open circuit voltage does not change. Hereinafter, the output loss generated when manufacturing a solar cell module from a solar cell is referred to as a CTM (Cell to Module) loss. FIG. 20 is a characteristic graph of FIG. In FIG. 19, the simulation is performed on the assumption that the short circuit current Isc is 9A.

The CTM loss is used as an index that represents the difference between the photoelectric conversion efficiency of the solar cell and the photoelectric conversion efficiency of the solar cell module, and is calculated here by the following equation. Further, in FIG. 19 and FIG. 20, the larger the numerical value, the smaller the CTM loss, and the smaller the numerical value, the more the CTM loss.

CTM loss = (1-output ratio) x 100 (%)
Power ratio = (short circuit current of the solar cell module Isc × F.F. Of the solar cell module) / {(short circuit current of the solar cell Isc × F.F. Of the solar cell) × (number of solar cells: 40 Sheet)}

From FIGS. 19 and 20, it can be seen that CTM loss does not always continue to increase as the number of tab lines increases. From FIGS. 19 and 20, it can be seen that when the number of tab lines increases, the CTM loss in the case of the round wire 0.5 mmφa is the smallest, and then the CTM loss in the case of the round wire 0.4 mmφa is smaller.

On the other hand, when the number of tab lines increases, in the case of flat angle 0.5wa × 0.25t and in the case of flat angle 0.8wa × 0.25t, the case of round wire 0.5 mmφa and the case of round wire 0.4mmφa In comparison, CTM loss is large. The CTM loss decreases in the case of 0.5 mmφa of round wire and 0.4 mmφa of round wire when the number of tab wires is increased, from the first effect of using tab wire 20 of the above-mentioned round wire. It is considered to be due to the third effect.

The CTM loss of a solar cell module having three surface bus bar electrodes of the prior art is around 3%. In the solar cell module 100 according to the first embodiment, light receiving surface bus electrodes having a width of 0.4 mm are juxtaposed in a range of 10 to 15 or a light receiving surface having a width of 0.5 mm. The bus electrodes are arranged in parallel in a range of 5 or more and 15 or less. That is, in the solar cell module 100, use of tab wire of round wire 0.4 mmφa in a range of 10 or more and 15 or less, or use of tab wire of round wire 0.5 mmφa in a range of 5 or more and 15 or less This makes it possible to halve the CTM loss to about 1.5% or less as compared with the solar cell module described in Patent Document 1. Furthermore, the difference in the manufacturing method makes it possible to reduce the material cost of the solar cell module by using the round tab wire which can be manufactured cheaper than the flat wire.

In the above, the thickness of the solder plating is very thin compared to the diameter φa of the round conductor or the width wa of the flat conductor, so the characteristics of the solar cell module tend to be the same as above even when the thickness of the solder plating is considered. Thus, the diameter φa of the round conductor and the width wa of the rectangular conductor can be treated as the diameter of the solder-plated tab wire 20. Therefore, in the solar cell module 100 according to the first embodiment, the tab wire 20 having a tab wire diameter φ of 0.4 mmφa is used in a range of 10 or more and 15 or less, or the tab wire diameter φ is round. By using the tab wire 20 of 0.5 mmφa in a range of 5 to 15, it is possible to reduce the CTM loss by half in comparison with the solar cell module described in Patent Document 1 to within about 1.5%. It will be possible to

In addition, the sheet resistance of the n-type impurity diffusion layer, which is the sheet resistance of the light receiving surface, is 70 Ω / sq within the range of 150 mm to 160 mm square of the square external dimensions of the square solar battery cell used in the above simulation. . 90 Ω / sq. The same characteristics as described above can be obtained even when the conditions are arbitrarily changed in the following range and the electrical resistance of the light receiving surface grid electrode in the range of 0.45 Ω / cm to 0.7 Ω / cm. These conditions are preferable conditions for achieving a high practical output. That is, even when the external dimensions of the solar battery cell, the sheet resistance of the light receiving surface, and the electric resistance of the light receiving surface grid electrode are arbitrarily changed in the above range, the characteristics of the solar battery cell and the solar battery module are as shown in FIG. It is confirmed by the inventor's simulation that the same tendency as the characteristics shown in FIG.

With regard to the conditions of the solar cells used in the above simulation, the distance between adjacent light receiving surface grid electrodes is in the range of 1 mm or more and 2 mm or less, and the number of light receiving surface grid electrodes is in the range of 75 or more and 150 or less Even when the conditions are arbitrarily changed, the same characteristics as described above can be obtained.

Therefore, in the solar cell module 100, the outer dimensions of the solar cell are in the range of 150 mm to 160 mm square, and the sheet resistance of the n-type impurity diffusion layer, which is the sheet resistance of the light receiving surface, is 70 Ω / sq. 90 Ω / sq. Under the following range and under the condition that the electrical resistance of the light receiving surface grid electrode is in the range of 0.45 Ω / cm to 0.7 Ω / cm, there are suitable conditions for the wire diameter and the number of tab wires 20. In the solar cell module 100, use a tab wire 20 having a tab wire diameter φ of 0.4 mmφa in a range of 10 to 15 or a tab wire 20 of a tab wire diameter φ of 0.5 mmφa Thinning the width of the light receiving surface bus electrode to the width of the tab wire 20 or less by using in the range of 5 or more and 15 or less, an appropriate condition of the wire diameter of the tab wire 20 and the number that can suppress CTM loss. You can say that.

Therefore, according to the solar cell module 100 according to the present invention, it is possible to suppress an increase in light blocking loss due to the shadow of the tab wire 20 connecting the plurality of solar cells 10 and the light receiving surface bus electrode 12B. The resistance loss at 12 G can be reduced to reduce the resistance loss at the time of taking out the current from the solar battery cell 10, and the solar cell module can be obtained in which cost reduction and high photoelectric conversion efficiency are realized.

In the case of a solar cell module using a tab wire made of flat rectangular conductors according to the prior art, for example, when the width of the tab wire is halved and the number is doubled, the state before changing the width and the number of tab wires is compared Then, the overall shadow loss is the same, and the current density of the current flowing through the tab line is the same, so the resistance loss at the tab line is also the same. On the other hand, when the width of the tab line is halved and the number is doubled, the light receiving surface grid electrode is generated by photoelectric conversion in the solar battery cell as compared with the state before changing the width and the number of tab lines. The resistance loss at the light receiving surface grid electrode is reduced because the maximum distance when the carrier that has reached f.sub.1 flows in the light receiving surface grid electrode is halved.

Therefore, as the total loss of the solar cell module, as the number of tab lines increases, the resistance loss at the light receiving surface grid electrode decreases and the output improves. That is, in view of the characteristics of the solar battery cell, it is preferable that the number of tab lines is large, but when the tab lines become thin, manufacturing of the solar cell module becomes difficult. For this reason, in practice, the number of tab wires is selected in view of the characteristics of the solar cell module and the manufacturing technology of the solar cell module. That is, in the prior art, it was generally understood that the characteristic of the solar cell module is improved by increasing the number by narrowing the tab lines.

On the other hand, when a round tab wire is used, if the width of the tab wire is reduced, the height of the tab wire is also reduced, the above theory does not hold. In addition, when a round tab wire is used, there is also a third effect of the above-mentioned round tab wire 20, which is the effect of light reflection, that is, the optical gain when using a round tab wire. Do. Therefore, it is not easy to find an appropriate configuration for the tab line.

In the process of simulation, in the process of simulation, the diffuse reflection effect of sunlight incident on the solar cell module by the tab wire of the round wire and the reflected light diffusely reflected by the tab wire of the round wire is on the solar cell side of the light receiving surface protection component After clarifying the effective light amount of sunlight incident on the solar cell module based on the critical angle when entering the inner surface which is the surface of the surface, transmittance conditions of sunlight on the light receiving surface side sealing material, etc. The simulation was done. Then, the inventor of the present invention aims to suppress the decrease in the output of the solar cell module due to the current collection loss of the generated current generated by the solar cell module by sunlight, that is, the solar cell module caused by the tab wire and the light receiving surface bus electrode In order to suppress the reduction of the power of the above, the above simulation has found that there is an appropriate number of tab lines as shown in FIG. 19 and FIG.

The configuration shown in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and one of the configurations is possible within the scope of the present invention. Parts can be omitted or changed.

DESCRIPTION OF SYMBOLS 10 solar battery cell, light receiving surface of 10 A solar battery cell, back surface of 10 B solar battery cell, 11 semiconductor substrate, light receiving surface of 11 A semiconductor substrate, back surface of 11 B semiconductor substrate, 12 light receiving surface electrode, 12 B light receiving surface bus electrode, 12 G light receiving Surface grid electrode, 13 back surface electrode, 13a back surface collecting electrode, 13b back surface contact electrode, 20 tab wire, 20a round wire conductor, 20b, thin layer of solder 300b, 300a light receiving surface side connection region, 23b rear surface side connection region, 24 Inter-cell area, 25 horizontal tab line, 31 light receiving surface protection component, 31a inner surface, 32 back surface protection component, 33 light receiving surface sealing material, 34 rear surface sealing material, 40 frame, 41 terminal box, 50 solar cell string, 70 solar array, 100 solar modules, 200 heat tools, 30 Flat tab wire, 300a flat conductor, L1, L2 shadow loss, m thin solder layer thickness, r round conductor radius, RL reflected light, S1 round conductor cross section, S2 flat conductor cross section, t flat angle Conductor thickness, w Flat tab wire width, wa Flat conductor width, φ Tab wire diameter, φa Round wire conductor diameter.

Claims

A solar cell module in which a plurality of solar cells electrically connected by a tab wire is disposed between a light-receiving side protection component having a light-transmitting property and a back-side protection component,
The solar battery cell is
a semiconductor substrate having a pn junction,
A plurality of grid electrodes extending parallel to a direction orthogonal to the connecting direction of the solar cells by the tab line on the light receiving surface of the semiconductor substrate and the plurality of grid electrodes on the light receiving surface are connected along the connecting direction A light receiving surface electrode having a plurality of light receiving surface bus electrodes extending;
A back surface electrode extending along the connection direction on the back surface of the semiconductor substrate facing the opposite side to the light receiving surface;
Equipped with
The tab line is
A round conductor is used as a base material and has the same diameter as the width of the light receiving surface bus electrode,
One is connected to one of the light receiving surface bus electrodes, and the same number as the light receiving surface bus electrodes is provided.
It extends along the connection direction and is connected to the upper surface of the light receiving surface bus electrode of one of the two adjacent solar cells, and the back electrode of the other solar cell. Connected and
The solar battery cell has a square shape in which the length of one side is in the range of 150 mm to 160 mm, and the sheet resistance of the light receiving surface is 70 Ω / sq. 90 Ω / sq. In the following range, under the condition that the resistance value of the grid electrode is not less than 0.45 Ω / cm and not more than 0.7 Ω / cm,
The light-receiving surface bus electrodes having a width of 0.4 mm are juxtaposed in a range of 10 to 15, and the light-receiving surface bus electrodes having a width of 0.5 mm are in a range of 5 to 15 Be placed side by side,
A solar cell module characterized by
The tab wire is that the surface of the conductor of the round wire is covered with solder,
The solar cell module according to claim 1, characterized in that
The solder is plated on the surface of the round conductor.
The solar cell module according to claim 2, characterized in that