TWI688110B - Solar battery unit and method for manufacturing solar battery unit - Google Patents

Abstract

A solar cell unit comprising: a plurality of thin wire electrodes (5a) extending toward a first direction of the in-plane direction of the semiconductor substrate (11) and crossing the first direction and arranged parallel to each other; and a plurality of the first set The electric electrodes are connected to two or more adjacent thin-line electrodes (5a) and are dispersedly arranged in a second direction crossing the first direction. The thin wire electrode (5a) not connected to the first collector electrode is at the same position as the first collector electrode in the first direction, and the width provided with the thin wire electrode (5a) is set to the thinner wire electrode (5a) The other areas are wider and belong to the tab line connecting portion (5c) for connecting the tab lines.

Description

Solar battery unit and method for manufacturing solar battery unit

The present invention relates to a solar cell provided with an electrode produced using an electrode material paste and a method of manufacturing the solar cell.

In the solar cell, reduction of manufacturing cost is an important issue. Among the manufacturing costs of solar cells, the cost of silver used for silver electrodes occupies an extremely large proportion. The silver electrode is mainly used for the light-receiving side electrode. The general light-receiving surface-side electrode is classified into the following two types: a plurality of thin-line electrodes formed to cover the entire surface of the solar cell and collecting current generated by the solar cell from the semiconductor substrate; and from the thin-line electrode A collector electrode that collects current. The thin wire electrode is also generally called a grid electrode, and the collector electrode is also called a bus bar electrode.

In addition to collecting current from the thin wire electrode, the collector electrode also plays a role in welding the wire called a tab wire, which is used to form a solar cell module. Adjacent solar cells are electrically connected to each other. The tab wire is generally made of copper (Cu), and a thickness of several hundred μm is used. The conductivity of copper is 1.7 μΩcm. In addition, the conductivity of silver is 1.6 μΩcm, which is a value close to that of copper. However, the price of silver is about 100 times the price of copper, which is extremely expensive compared to copper.

The solar battery unit is finally modularized by connecting a plurality of solar battery units of about 10 to 60 pieces with a bonding wire. Therefore, in terms of the collector electrode of the final solar cell module, both the collector electrode of the solar cell unit and the tab wire connecting the collector electrodes of the solar cell unit are included. From the viewpoint of conductivity and material cost, by suppressing the concentration as much as possible The amount of silver used for the electric electrode and the thickness of the copper bonding wire are thickened to control the resistance loss of the collector electrode of the solar cell module, which is closely related to the reduction in the manufacturing cost of the solar cell module.

On the other hand, when considering the metal surface that is connected to the tab wire by welding, that is, the role of the collector electrode of the connected surface, the bonding strength of the collector electrode and the tab wire achieved by welding changes It's important. From the viewpoint of reducing the manufacturing cost of the solar cell, it may be considered to reduce the area of the collector electrode in the in-plane direction of the solar cell. However, when the area of the collector electrode is reduced, there is a problem that the bonding strength decreases in proportion to the amount of reduction in the bonding area to be welded.

In addition, in recent years, in order to reduce the manufacturing hours of solar battery cells and to reduce the amount of electrode materials such as silver paste used to reduce the manufacturing cost, solar battery cells without a collector electrode have also been reviewed. unit. In Patent Document 1, it has been disclosed that a bus bar electrode which is a collector electrode is not provided, but the tab wire is directly crossed by intersecting a finger electrode through a conductive adhesive film. The solar cell unit without the bus bar structure is next.

[Prior Technical Literature]

[Patent Literature]

Patent Literature 1: Japanese International Publication No. 2012/077556

However, in the electrode structure without the bus bar electrode shown in the above-mentioned Patent Document 1, there is a bonding strength between the electrode on the light-receiving surface side of the solar battery cell and the tab wire, that is, the finger electrode and the tab wire In terms of adhesion strength, it is impossible to obtain practical strength of adhesion strength. Here, it is also conceivable to work on the construction of the tab wire to obtain a practical level of adhesive strength. However, in this case, in order to accompany the device including the finger electrode that is to weld the tab wire to the solar cell The change of the manufacturing device of the solar cell module inside will require huge equipment investment.

The present invention was developed in view of the above problems, and its object is to obtain a solar battery cell that can reduce the amount of electrode material used while ensuring the bonding strength of the tab wire and the electrode that electrically connect the solar battery cells to each other.

In order to solve the above-mentioned problems and achieve the objective, the solar cell unit of the present invention includes: a semiconductor substrate having a pn junction; a plurality of thin wire electrodes are provided on one surface of the semiconductor substrate, facing the first in the in-plane direction of the semiconductor substrate 1 direction extends, and the in-plane direction of the semiconductor substrate crosses the first direction and is arranged parallel to each other; and a plurality of first collector electrodes are provided on one surface of the semiconductor substrate and connect two or more adjacent thin-line electrodes In addition, they are distributed in a second direction that intersects the first direction. The plurality of thin-line electrodes have a thin-line electrode connected to the first collector electrode, and a thin-line electrode not connected to the first collector electrode; the thin-line electrode not connected to the first collector electrode is connected to the first direction The first collector electrode is located at the same position, and is provided with a tab wire connecting portion that belongs to a region for connecting the tab wire and has a wider width than the other areas of the thin wire electrode.

The solar battery cell of the present invention can achieve the effect of obtaining a solar battery cell that can ensure the bonding strength of the tab wire and the electrode that electrically connect the solar battery cells to each other, and can reduce the amount of electrode material used.

1. 54‧‧‧Solar battery unit

2.11‧‧‧Semiconductor substrate

2a‧‧‧ 1st side

2b‧‧‧ 2nd side

2c‧‧‧3rd side

2d‧‧‧4th side

3‧‧‧n-type impurity diffusion layer

4‧‧‧Anti-reflection film

5‧‧‧Receiving side electrode

5a‧‧‧fine wire electrode

5b‧‧‧collector electrode on the light-receiving side

5c‧‧‧Connecting part

5c1‧‧‧The first wire connection

5c2‧‧‧Second wire connection

5c3‧‧‧The third wire connection part

5c4‧‧‧Connecting part of the 4th wire

5d‧‧‧The second collector electrode

7‧‧‧Back aluminum electrode

8‧‧‧Back bus bar electrode

9‧‧‧Back side electrode

10‧‧‧p+ layer

21‧‧‧Splice line

31‧‧‧Silver paste

41‧‧‧Print mask

41a‧‧‧Top

42‧‧‧mesh

43‧‧‧Latex

44‧‧‧Opening

45‧‧‧Scraper

46‧‧‧First opening

47‧‧‧The second opening

51, 52, 53, 55 ‧‧‧ another solar battery unit

61‧‧‧Current terminal

62‧‧‧Voltage terminal

X1‧‧‧Width of thin wire electrode

X1a‧‧‧Opening width

X2‧‧‧The width of the connecting part

X2a‧‧‧Opening width

X3‧‧‧ Spacing between adjacent thin wire electrodes

X4‧‧‧ Fine wire electrode spacing

Y1‧‧‧Length of the connecting part

[FIG. 1] It is the top view which looked at the solar cell unit of Embodiment 1 of this invention from the light-receiving surface side.

[Figure 2] is a bottom view of the solar cell unit according to Embodiment 1 of the present invention viewed from the back side facing the side opposite to the light receiving surface.

[Figure 3] is a main part for explaining the cross-sectional structure of the solar battery cell according to Embodiment 1 of the present invention The cross-sectional view is a cross-sectional view of the main part in the line III-III of FIG. 1.

[FIG. 4] It is a cross-sectional view of the main part for explaining the cross-sectional structure of the solar battery cell according to Embodiment 1 of the present invention, and is a cross-sectional view of the main part in the line segment IV-IV of FIG.

[FIG. 5] This is an enlarged view of a main part in which the thin-line electrode of the solar battery cell according to Embodiment 1 of the present invention is enlarged and displayed.

[FIG. 6] It is the top view which looked at the state which connected the tab wire to the thin wire electrode of the solar cell unit of Embodiment 1 of this invention from the light-receiving surface side.

[Figure 7] is a flowchart illustrating a procedure for manufacturing steps of a solar battery cell according to Embodiment 1 of the present invention.

[FIG. 8] It is a top view which shows the state which printed the silver paste for forming the light-receiving side electrode of Embodiment 1 of this invention on the p-type polycrystalline silicon substrate.

[FIG. 9] It is a schematic cross-sectional view explaining the screen printing of the light-receiving side electrode of Embodiment 1 of this invention.

[Fig. 10] This is an enlarged view of a main part of an enlarged display of an opening in a printing mask used for screen printing of a light-receiving side electrode according to Embodiment 1 of the present invention.

[Figure 11] is a plan view of another solar battery cell according to Embodiment 1 of the present invention viewed from the light-receiving surface side.

[Fig. 12] This is an enlarged view of a main part in which the thin-line electrode of another solar battery cell according to Embodiment 1 of the present invention is enlarged and displayed.

[FIG. 13] It is the top view which looked at the state where the tab wire is connected to the thin-line electrode of another solar cell unit of Embodiment 1 of this invention from the light-receiving surface side.

[Figure 14] is a plan view of another solar cell unit according to Embodiment 1 of the present invention viewed from the light-receiving surface side.

[Fig. 15] It is an enlarged display of the thin-line electrode of another solar battery cell according to Embodiment 1 of the present invention. An enlarged view of the main part shown.

[FIG. 16] It is the top view which looked at the state where the tab wire is connected to the thin-line electrode of another solar cell unit of Embodiment 1 of this invention from the light-receiving surface side.

[Figure 17] is a plan view of another solar battery cell according to Embodiment 1 of the present invention viewed from the light-receiving surface side.

[Figure 18] is a plan view of the solar battery cell according to Embodiment 2 of the present invention viewed from the light-receiving surface side.

[Figure 19] is a plan view of another solar battery cell according to Embodiment 2 of the present invention viewed from the light-receiving surface side.

[FIG. 20] FIG. 20 is a cross-sectional view showing a state in which a current terminal and a voltage terminal are in contact with a tab wire connection portion of a solar cell in Embodiment 3 of the present invention, and is a cross-sectional view along the second direction.

The solar cell and the manufacturing method of the solar cell according to the embodiment of the present invention will be described in detail below. In addition, the present invention is not limited to this embodiment.

Embodiment 1

Fig. 1 is a plan view of the solar battery cell 1 according to Embodiment 1 of the present invention viewed from the light-receiving surface side. Fig. 2 is a bottom view of the solar battery cell 1 according to Embodiment 1 of the present invention viewed from the back side facing the side opposite to the light receiving surface. FIG. 3 is a cross-sectional view of main parts for explaining the cross-sectional structure of the solar cell 1 according to Embodiment 1 of the present invention, and is a cross-sectional view of main parts in the line segment III-III of FIG. 1. Fig. 3 is a cross-sectional view of a main part of a solar battery cell 1 where a tab wire connecting portion 5c is formed. FIG. 4 is a cross-sectional view of main parts for explaining the cross-sectional structure of the solar battery cell 1 according to Embodiment 1 of the present invention, and is a cross-sectional view of main parts in the line segment IV-IV of FIG. 1. FIG. 4 is a cross-sectional view of a main part of a solar battery cell 1 where a collector electrode 5b on the light-receiving surface side is formed.

In the solar cell 1 of the first embodiment, it is composed of p-type polycrystalline silicon On the light-receiving surface side of the semiconductor substrate 2, an n-type impurity diffusion layer 3 is formed by phosphorus diffusion, a semiconductor substrate 11 having a pn junction is formed, and a silicon nitride (SiN) film is formed on the n-type impurity diffusion layer 3组合的反防膜4。 The anti-reflection film 4 is composed. In addition, the semiconductor substrate 2 is not limited to p-type polycrystalline silicon substrates, and substrates such as p-type single crystal silicon substrates, n-type polycrystalline silicon substrates, and n-type single crystal silicon substrates can also be used. . In addition, the semiconductor substrate 2 is not limited to a silicon substrate, and a semiconductor substrate generally used for a crystalline solar cell can be used.

In addition, the surface of the semiconductor substrate 11 on the light-receiving surface side, that is, the surface of the n-type impurity diffusion layer 3 on the light-receiving surface side is formed with a fine structure (not shown) as a texture structure. The micro concave-convex system is formed to increase the area of the light-receiving surface that absorbs light from the outside, suppresses the reflectance of the light-receiving surface, and seals the light.

In addition, on the light-receiving surface side of the semiconductor substrate 11, a light-receiving surface-side electrode 5 belonging to the first electrode is formed. The light-receiving surface-side electrode 5 includes a plurality of long thin wire electrodes 5a and a plurality of light-receiving surface-side collector electrodes 5b belonging to the first collector electrode, and is reflected on the surface of the semiconductor substrate 11 on the light-receiving surface side Formed in a state surrounded by 4.

Hereinafter, the direction parallel to the first side 2a and the second side 2b belonging to a pair of sides of the solar battery cell 1 and the direction corresponding to the Y direction in FIG. 1 is referred to as the first direction. In addition, the direction parallel to the third side 2c and the fourth side 2d belonging to the other pair of sides of the solar battery cell 1 and the direction corresponding to the X direction in the first drawing is referred to as the second direction. Therefore, the second direction is a direction orthogonal to the first direction in the in-plane direction of the semiconductor substrate 2.

The thin wire electrode 5a is mainly composed of silver, and a plurality of parallel electrodes are provided in parallel. When a solar cell 1 with a silicon substrate of 156 mm square shape is used, the thin wire electrode 5a has a width in the range of 20 μm or more and 100 μm or less, and 70 or more and 300 or less are arranged in parallel at predetermined intervals The number of left and right ranges. The thin wire electrode 5a is electrically connected to the n-type impurity diffusion layer 3 in the bottom surface portion.

The collector electrode 5b on the light-receiving surface side has a crossing portion that intersects the thin-line electrode 5a, and is electrically connected to the plural thin-line electrodes 5a, and a plurality of intermittently are provided. That is, the light-receiving surface-side collector electrode 5b is arranged side by side in parallel with the second direction in a state crossing the thin wire electrode 5a. The light-receiving surface-side collector electrode 5b has a width of 1 mm or more and 2 mm or less, and an average number of 2 or more and 5 or less pieces of solar cells are arranged, and the electricity collected through the thin wire electrode 5a is taken out to the outside . In the first embodiment, an example is shown in which four collector electrodes 5b on the light-receiving surface side are intermittently provided. Here, although the plurality of light-receiving surface-side collector electrodes 5b are intermittently provided along the second direction, the plurality of light-receiving surface-side collector electrodes 5b arranged at the same position in the first direction can be regarded as 1 as a whole Article. In addition, in the collector electrode 5b on the light-receiving surface side, when the solar battery cells 1 are connected to each other to form a module, as will be described later, a tab wire 21 is connected.

On the other hand, on the back surface facing the opposite side of the light-receiving surface of the semiconductor substrate 11, the entire back surface except for a part of the marginal area is provided with a back aluminum electrode 7 made of an aluminum material, and further provided with silver as the main body结构的背BUS板8。 The rear bus bar electrode 8. In addition, in the solar battery cell 1, the back side electrode 9 belonging to the second electrode is constituted by the back aluminum electrode 7 and the back bus bar electrode 8.

In addition, a p+ layer 10 belonging to a BSF (Back Surface Field) containing a high-concentration impurity is formed in the surface layer portion on the back surface side of the semiconductor substrate 11 and directly below the back aluminum electrode 7. The p+ layer 10 is provided to obtain the BSF effect, and an electron field in a band structure is used to increase the electron concentration in the semiconductor substrate 2 so that the electrons in the semiconductor substrate 2 belonging to the p-type layer are not destroyed.

In the solar battery cell 1 configured in this manner, when sunlight is irradiated from the light-receiving surface side of the solar battery cell 1 to the semiconductor substrate 11, holes and electrons are generated. The generated electrons move toward the n-type impurity diffusion layer 3 by the electric field of the pn junction, that is, the junction surface of the semiconductor substrate 2 and the n-type impurity diffusion layer 3. The generated holes move toward the semiconductor substrate 2 by the electric field of the pn junction, that is, the junction surface of the semiconductor substrate 2 and the n-type impurity diffusion layer 3. Due to this, the n-type impurities The diffusion layer 3 will have a surplus of electrons, and the semiconductor substrate 2 will have a surplus of holes, and as a result, a photovoltaic force will be generated. The photoelectromotive force is generated in a direction that biases the pn junction in the forward direction, the light-receiving surface-side electrode 5 connected to the n-type impurity diffusion layer 3 becomes a minus electrode, and the back surface-side electrode 9 connected to the semiconductor substrate 2 becomes positive ( plus) pole, current will flow to an external circuit (not shown).

Next, the details of the light-receiving surface-side electrode 5 which is a feature of the solar cell 1 of the first embodiment will be described. The electrode material of the light-receiving surface-side electrode 5 of the silicon solar battery cell generally uses silver paste, for example, boron glass is added. The glass is in the form of a frit, for example, lead (Pb) is 5wt% to 30wt%, boron (B) is 5wt% to 10wt%, silicon (Si) is 5wt% to 15wt%, oxygen (O) is It is composed of 30wt% to 60wt% of the composition, and in addition, there are cases where several wt% of zinc (Zn) and cadmium (Cd) are mixed. Such a lead-boron glass has the property of melting under heating at a temperature of about 800°C and corroding silicon, for example. In addition, in general, in the method of manufacturing a crystalline silicon solar cell, a method of obtaining electrical contact between a silicon substrate and a silver paste using the characteristics of a glass frit is used. In the solar cell 1, silver paste is also used as the electrode material of the light-receiving surface-side electrode 5.

Fig. 5 is an enlarged view of a main part in which the thin-line electrode 5a of the solar battery cell 1 according to Embodiment 1 of the present invention is enlarged and displayed. Fig. 6 is a plan view of the state where the tab wire 21 is connected to the thin wire electrode 5a of the solar battery cell 1 according to Embodiment 1 of the present invention when viewed from the light receiving surface side.

In the light-receiving surface-side electrode 5 of the solar battery cell 1 of the first embodiment, a plurality of thin wire electrodes 5a are intermittently provided to collect current, and a bonding wire 21 is generally called a bus bar electrode. Collector electrode 5b on the light-receiving surface side. A plurality of thin-line electrodes 5a are connected to the light-receiving surface-side collector electrode 5b. That is, the light-receiving surface-side collector electrode 5b is provided on the light-receiving surface belonging to one surface of the semiconductor substrate 11, and connects two or more adjacent thin-line electrodes 5a, and a plurality of dispersedly arranged in the second direction. The light-receiving surface-side collector electrode 5b is connected to a part of the plurality of thin-line electrodes 5a. Therefore, in the thin wire electrode 5a, there are the thin wire electrode 5a connected to the light-receiving surface-side collector electrode 5b and the thin wire electrode 5a not connected to the light-receiving surface-side collector electrode 5b. By this, compared to the bus bar electrode is connected to In the case where all the thin wire electrodes 5a are continuously provided, the amount of silver used for the bus bar electrode can be further reduced.

In the first embodiment, the light-receiving-surface-side collector electrode 5b is set to have an area of one-half when forming a continuous general bus bar electrode connected to all the thin wire electrodes 5a. The length of the light-receiving surface-side collector electrode 5b in the second direction is determined by taking into account the peel strength between the light-receiving surface-side collector electrode 5b and the tab wire 21 and the amount of electrode material used. The shorter the length of the light-receiving surface-side collector electrode 5b in the second direction, the less the amount of electrode material used, and the manufacturing cost of the solar battery cell 1 will be reduced. On the other hand, the longer the length of the light-receiving surface-side collector electrode 5b in the second direction, the stronger the peel strength between the light-receiving surface-side collector electrode 5b and the tab wire 21. From the viewpoint of the amount of electrode material used, the total length of the plurality of light-receiving-side collector electrodes 5b after being dispersed and arranged in one light-receiving-side collector electrode 5b, when the outline of the solar cell 1 is In the case of a square shape, it is better to be smaller than 1/2 of the length of one side of the square shape.

The length of the light-receiving surface-side collector electrode 5b in the second direction is preferably at least five times the width of the light-receiving surface-side collector electrode 5b in order to ensure peel strength. For example, in the solar cell 1 having a square shape with an outer shape of 156 mm square, when four light-receiving surface-side collector electrodes 5 b with a width of 1 mm are formed, the length of the light-receiving surface-side collector electrode 5 b is preferably 5 mm or more.

The light-receiving surface-side electrode 5 of the solar battery cell 1 is provided with a thin wire electrode 5a that is not connected to the light-receiving surface-side collector electrode 5b, and a tab wire connecting portion 5c is provided. The tab wire connection portion 5c is provided in the light-receiving surface-side electrode 5 at the same position as the light-receiving surface-side collector electrode 5b in the first direction. The tab wire connecting portion 5c is a connecting portion for welding the tab wires 21 that electrically connect the solar battery cells 1 to each other when a plurality of solar battery cells 1 are used to form a solar battery module, and is a thin wire In the electrode 5a, a part of the width is a wide area. That is, in the surface of the solar cell unit 1 on the light-receiving surface side, in the region where the tab wire connecting portion 5c is formed, the average of the tab wire connecting portion 5c in the surface of the solar cell unit 1 on the light-receiving surface side The area of the electrode per unit area is wider than other areas in the thin wire electrode 5a. that is, In the area where the tab wire connection portion 5c is formed, the electrode arrangement area is wider than other areas in the thin wire electrode 5a.

In this way, in the solar cell 1, the light-receiving surface side electrode 5 can be connected to the tab wire 21 rather than simply welding the tab wire 21 to the thin wire electrode 5 a that does not have the tab wire connecting portion 5 c. The welding area is widened. Therefore, when the tab wire 21 is welded to the light-receiving surface-side electrode 5, a practical level of joint strength can be obtained between the thin wire electrode 5 a and the tab wire 21 without peeling of the tab wire 21.

As shown in FIG. 1, the plurality of thin-line electrodes 5 a are arranged in the second direction in a plane along the first direction in the longitudinal direction of the solar cell unit 1. The solar cell 1 has a first side 2a and a second side 2b belonging to a pair of sides, and a third side 2c and a fourth side 2d belonging to another pair of sides in the in-plane direction of the semiconductor substrate 2 The square shape. The length of one side of the square shape is, for example, 156 mm.

The tab wire connecting portion 5c is in the plane of the solar battery cell 1 and has a rectangular shape whose longitudinal direction is set along the direction of the first direction. Each thin wire electrode 5a is provided with a first tab wire connecting portion 5c1, a second tab wire connecting portion 5c2, and a third terminal in the first direction, that is, the longitudinal direction of the thin wire electrode 5a at equal intervals The four tab wire connecting portions 5c of the tab wire connecting portion 5c3 and the fourth tab wire connecting portion 5c4 serve as the tab wire connecting portion 5c.

As shown in FIG. 6, the tab wire 21 is welded to the tab wire connecting portion 5c with the longitudinal direction as the second direction, that is, along the X direction in FIG. 6. Therefore, in the plurality of thin wire electrodes 5a, the arrangement position of the first tab wire connecting portion 5c1 in the first direction is set to the same position as shown in FIG. Similarly, in the plurality of thin wire electrodes 5a, the arrangement position of the second tab wire connection portion 5c2 in the first direction is set to the same position, and the arrangement position of the third tab wire connection portion 5c3 in the first direction It is set to the same position, and the arrangement position of the fourth tab wire connecting portion 5c4 in the first direction is set to the same position.

That is, the first tab wire connecting portion 5c1 in the plurality of thin wire electrodes 5a, the arrangement direction is It is assumed that the direction is along the second direction, and the arrangement is along the second direction. Similarly, the second tab wire connecting portion 5c2 of the plurality of thin wire electrodes 5a is arranged along the second direction, and the third tab wire connecting portion 5c3 of the plurality of thin wire electrodes 5a is arranged along the second direction, plural In the thin wire electrode 5a, the fourth tab wire connecting portion 5c4 is arranged along the second direction. In addition, in the plurality of thin wire electrodes 5a, the arrangement position of the tab wire connecting portion 5c in the first direction is set to correspond to the rear bus bar electrode 8 of the rear electrode 9.

As shown in FIG. 5, in the tab wire connecting portion 5c, the width of the tab wire connecting portion 5c in the direction orthogonal to the longitudinal direction of the thin wire electrode 5a, that is, the width X2 of the tab wire connecting portion, The width is wider than the width X1 of the thin wire electrode. The longitudinal direction of the thin wire electrode 5a corresponds to the first direction. The direction orthogonal to the longitudinal direction of the thin wire electrode 5a corresponds to the second direction. In the tab wire connecting portion 5c, the width of the tab wire connecting portion 5c in the long-side direction of the thin wire electrode 5a, that is, the length Y1 of the tab wire connecting portion, in order not to reduce the light receiving area, is The width of the line 21 is preferably equal. However, when considering the positional deviation when the tab wire 21 is connected to the tab wire connecting portion 5c, the length Y1 of the tab wire connecting portion may be set wider than the width of the tab wire 21. In addition, in FIG. 6, in order to understand the positional relationship between the tab wire connecting portion 5c and the tab wire 21, it shows a case where the length Y1 of the tab wire connecting portion is set wider than the width of the tab wire 21 .

In addition, in order to enhance the bonding strength of the bonding wire connection portion 5c and the bonding wire 21 by welding, the bonding area of the bonding wire connection portion 5c and the bonding wire 21 is enlarged, that is, the bonding wire connection The welding area of the portion 5c and the tab wire 21 is preferably. For example, the width X2 of the connection portion of the tab wire is preferably more than twice the width X1 of the thin wire electrode. On the other hand, when the width X2 of the connection portion of the tab wire becomes wider, the area of the light-receiving surface-side electrode 5 in the plane of the solar cell 1 increases and the amount of silver used increases. Therefore, the width X2 of the connection portion of the tab wire is preferably equal to or less than the interval X3 between the adjacent thin wire electrodes. That is, the width X2 of the connection portion of the tab line is preferably not more than half of the pitch X4 of the thin wire electrode in the second direction. The arrangement distance X4 of the thin wire electrodes in the second direction is the interval between the center positions of the adjacent thin wire electrodes 5a in the second direction.

In the first embodiment, as will be described later, the height of the thin wire electrode 5a including the tab wire connecting portion 5c can be formed to be higher than the bus bar when a continuous general bus bar electrode connected to all the thin wire electrodes 5a is provided The height of the row bar electrode is higher, for example, it can be set to 15 μm. On the other hand, since the height of the continuous general bus bar electrode connected to all the thin wire electrodes 5a is about 10 μm, the height of the tab wire connection portion 5c is higher than that of the bus bar electrode. Therefore, from the viewpoint of height, the amount of silver used in the tab wire connection portion 5c per unit area in the plane direction of the semiconductor substrate 2 increases. Therefore, for example, if the width X2 of the tab wire connecting portion is set to be half or less of the arrangement pitch X4 of the thin wire electrodes in the second direction, even considering the area of the tab wire connecting portion 5c, it can still be derived from The height of the common bus bar electrode increases the height of the silver wire connection portion 5c, and the increase in the amount of silver used results in the light-receiving surface side electrode 5 because the area where the bus bar electrode is not formed is provided. The reduction in the amount of silver caused by the reduction in the area is offset, and the amount of silver can be further reduced.

Furthermore, from ensuring that the bonding strength of the tab wire connecting portion 5c and the tab wire 21 by welding does not cause peeling of the tab wire 21 at a practical level, and the reduction of the light-receiving side electrode 5 From the viewpoint of the amount of silver used, the width X2 of the tab wire connecting portion is set to be larger than the width of the thin wire electrode 5a other than the tab wire connecting portion 5c, and is the thickness of the thin wire electrode in the second direction It is better to arrange the range below one and a half of the pitch X4. In addition, since the thin wire electrode 5a including the tab wire connecting portion 5c is formed by screen printing, a slight width variation occurs depending on the part. Therefore, the width X2 of the tab wire connecting portion is set such that the width of the thin wire electrode 5a other than the tab wire connecting portion 5c in the average value of the length Y1 of the tab wire connecting portion is larger and is in the second direction It is preferable that the range of the arrangement pitch of the thin wire electrodes is less than one-half of X4. When the width X2 of the tab wire connecting portion is equal to or smaller than the width of the thin wire electrode 5a other than the tab wire connecting portion 5c, the practical level bonding strength of the tab wire connecting portion 5c and the tab wire 21 cannot be ensured. When the width X2 of the connection portion of the tab wire is larger than one-half of the arrangement pitch X4 of the thin wire electrodes in the second direction, the effect of reducing the amount of silver used in the light-receiving side electrode 5 becomes lower.

Next, an example of a method of manufacturing the solar battery cell 1 will be described with reference to FIG. 7. 7th FIG. 1 is a flowchart illustrating the procedure of the manufacturing steps of the solar cell 1 according to Embodiment 1 of the present invention. In addition, the steps described here are the same as the manufacturing steps of a general solar cell using a silicon substrate, so the general manufacturing steps are not particularly shown.

First, for example, a p-type polycrystalline silicon substrate is prepared as the semiconductor substrate 2, and the p-type polycrystalline silicon substrate is washed with hydrogen fluoride and pure water. After that, in step S10, fine irregularities are formed on the surface of the p-type polycrystalline silicon substrate to form a texture structure on the surface. In terms of texture formation, for example, a p-type polycrystalline silicon substrate is immersed in a mixed acid solution mainly composed of hydrogen fluoride acid and nitric acid, and a concave-convex structure reflecting the shape when sliced is formed on the surface of the p-type polycrystalline silicon substrate.

In addition, when a single crystal silicon substrate is used as the semiconductor substrate 2, the single crystal silicon substrate is immersed in an alkaline solution, and a random pyramid is formed by anisotropic etching, thereby forming minute irregularities. In addition, it does not ask what is the formation method of the minute irregularities.

Next, in step S20, a pn junction is formed on the semiconductor substrate 2. The formation of the pn junction is performed by performing a diffusion step of diffusing phosphorus oxychloride (POCl ₃ ) by thermal diffusion on a p-type polycrystalline silicon substrate having a textured structure formed on the surface. In the diffusion step, for example, the p-type polycrystalline silicon substrate is thermally diffused at a high temperature by vapor phase diffusion method in phosphorus oxychloride (POCl ₃ ) gas to form phosphorus (P) diffused in the p-type polycrystalline silicon substrate The n-type impurity diffusion layer 3 formed of the surface layer forms a pn junction. For example, the p-type polycrystalline silicon substrate is heated at a temperature of 800° C. to 900° C. for 1 minute to 10 minutes, thereby forming the n-type impurity diffusion layer 3. The n-type impurity diffusion layer 3 is formed on the entire surface of the p-type polycrystalline silicon substrate. In addition, the n-type impurity diffusion layer 3 can be formed by solid-phase diffusion, regardless of the method for forming the n-type impurity diffusion layer 3.

Here, on the surface of the p-type polycrystalline silicon substrate immediately after the formation of the n-type impurity diffusion layer 3, a phosphor glass (Phosphorus Silicate Grass: PSG) composed mainly of the oxide of phosphorus formed during the vapor-phase diffusion of phosphorus is formed )Floor. Therefore, the phosphorous glass layer on the surface of the p-type polycrystalline silicon substrate is removed by a chemical solution such as hydrofluoric acid solution.

Next, in step S30, the back electrode 9 belonging to the p-type electrode is The electrode 5 on the light-receiving surface side of the n-type electrode is electrically insulated by pn separation to obtain a semiconductor substrate 11. The pn separation can be achieved by immersing only the back surface of the p-type polycrystalline silicon substrate on which the n-type impurity diffusion layer 3 is formed into a mixed acid solution mainly composed of hydrogen fluoride acid and nitric acid, and forming the n-type on the back surface of the p-type polycrystalline silicon substrate The impurity diffusion layer 3 is removed. Thereby, a semiconductor substrate 2 composed of p-type polycrystalline silicon belonging to the first conductivity type layer and an n-type impurity diffusion layer 3 belonging to the second conductivity type layer formed on the light-receiving surface side of the semiconductor substrate 2 can be obtained. The semiconductor substrate 11 constituting the pn junction. In addition, pn separation can also be performed by cutting and removing the n-type impurity diffusion layer 3 formed on the outer peripheral portion of the p-type polycrystalline silicon substrate by laser irradiation.

Next, in step S40, on the light-receiving surface side of the p-type polycrystalline silicon substrate on which the n-type impurity diffusion layer 3 is formed, for surface protection and photoelectric conversion efficiency improvement, for example, by plasma chemical vapor growth (Plasma-Enhanced Chemical Vapor Deposition: PECVD method is used to form silicon nitride (SiN) as the anti-reflection film 4.

Next, in step S50, the back-side electrode 9 is printed on the p-type polycrystalline silicon substrate by screen printing and dried. That is, by screen printing on the back side of the p-type polysilicon substrate, the aluminum paste belonging to the electrode material paste is applied to the shape of the back aluminum electrode 7, and the silver paste belonging to the electrode material paste is further applied to The shape of the rear bus bar electrode 8 is dried.

Next, in step S60, the light-receiving surface-side electrode 5 is printed on the p-type polycrystalline silicon substrate by screen printing and printed. That is, on the antireflection film 4 on the light-receiving surface side of the p-type polycrystalline silicon substrate, a printing mask formed with an opening corresponding to the shape of the electrode 5 on the light-receiving surface side, as shown in FIG. After the silver paste 31 of the electrode material paste is applied to the shape of the light-receiving side electrode 5 by screen printing, the silver paste 31 is dried. FIG. 8 is a plan view showing a state where the silver paste 31 for forming the light-receiving surface side electrode in Embodiment 1 of the present invention is printed on a p-type polycrystalline silicon substrate.

At this time, when compared with a solar cell unit having a thin wire electrode of the same height and connected to a continuous general bus bar electrode of all the thin wire electrodes, a more common sink will be formed The tab connection part 5c with a higher bar electrode. Fig. 9 is a schematic cross-sectional view illustrating screen printing of the light-receiving surface-side electrode 5 according to Embodiment 1 of the present invention. Fig. 10 is an enlarged view of a main part of an enlarged display of the opening 44 in the screen mask 41 used in the screen printing of the light-receiving surface-side electrode 5 according to Embodiment 1 of the present invention.

The printing mask 41 used for printing on the light-receiving-side electrode 5 is also the printing mask 41 used when printing the light-receiving-side collector electrode 5b, the thin wire electrode 5a, and the tab wire connecting portion 5c as a whole, as shown in the first section. As shown in Figure 9, it is a part called mesh 42 formed by weaving a metal wire with a wire diameter of 10 μm to 100 μm, forming a film of an organic component called latex 43, and will be printed accordingly The latex 43 in the region is removed to form the opening 44. In FIG. 10, the opening 44 for printing the thin wire electrode 5a and the tab wire connecting portion 5c is shown. When printing the silver paste 31, the silver paste 31 is applied to the printing mask 41, and a plate member made of rubber called a squeegee 45 is directed toward the predetermined position on the printing mask 41 Moves in the direction of and presses from the opening 44 of the silver paste 31 below the printing mask 41, thereby printing the electrode.

Here, although the light-receiving surface-side electrode 5 includes the thin wire electrode 5a and the tab wire connection portion 5c and the light-receiving surface side collector electrode 5b, the width of the thin wire electrode 5a is 20 μm or more, and the width is not more than 100 μm, and the width is narrow . As shown in FIG. 10, the first opening 46 which belongs to the opening corresponding to the thin wire electrode 5a in the opening 44 corresponds to the width of the printed thin wire electrode 5a, and is the same size as the width X1 of the thin wire electrode or It is formed larger than the width X1 of the thin-line electrode. Therefore, the opening width X1a of the first opening 46 that belongs to the opening width corresponding to the width X1 of the thin wire electrode is narrow, and it is difficult to stably print the silver paste 31 into the shape of the thin wire electrode 5a.

Therefore, the moving direction of the doctor blade 45 on the printing mask 41 is set to the same direction as the long-side direction of the printed thin-line electrode 5a, that is, the same direction as the long-side direction of the first opening 46 . As a result, when the doctor blade 45 is moved over the printing mask 41, the longitudinal direction of the first opening 46 and the contact surface between the upper surface 41a of the printing mask and the doctor blade 45 become positive cross. That is, the first opening The longitudinal direction of the portion 46 is orthogonal to the longitudinal direction of the lower end of the blade 45. In addition, the lower end of the doctor blade 45 is held by the upper surface 41a of the printing mask located between the first openings 46 adjacent to the longitudinal direction of the lower end of the doctor blade 45. Therefore, the squeegee 45 does not fall into the opening 44 and the silver paste 31 can be printed with a desired thickness.

On the other hand, the width X2 of the tab wire connecting portion is set to be larger than the width of the thin wire electrode 5a other than the tab wire connecting portion 5c, and is not more than half of the arrangement pitch X4 of the thin wire electrode in the second direction Scope. When the arrangement pitch X4 of the thin wire electrodes in the second direction is 0.5 mm or more and 2 mm or less, the width X2 of the tab wire connection portion is set to a range of 0.25 μm or more and 1 mm or less. Furthermore, the second opening 47 in the opening 44 belonging to the opening of the corresponding tab wire connecting portion 5c corresponds to the width X2 of the tab wire connecting portion, and is the same as the width X2 of the tab wire connecting portion Or larger than the width X2 of the connection part of the tab wire. Therefore, the opening width X2a belonging to the opening width X2 of the corresponding tab line connecting portion in the second opening 47 is wider than the opening width X1a. However, the opening width Xa2 is narrower than the width of a general bus bar electrode. The width of a common bus bar electrode is in the range of 1 mm or more and 2 mm or less.

When printing the silver paste 31 by setting the moving direction of the blade 45 on the printing mask 41 to the same direction as the longitudinal direction of the first opening 46, the lower end of the blade 45 is positioned at the The area of the 2 opening 47 is held by the upper surface 41 a of the printing mask located between the second openings 47 adjacent to the longitudinal direction of the lower end of the blade 45. Therefore, the squeegee 45 does not fall into the second opening 47, and the silver paste 31 can be printed with the same desired thickness as the first opening 46.

In addition, when the solar battery cell includes a bus bar electrode, the width of the bus bar electrode is generally 1 mm or more and 2 mm or less, which is much wider than the width of the thin wire electrode. In addition, the bus bar electrode is formed in a direction orthogonal to the grid electrode, that is, the thin wire electrode. In addition, since the moving direction of the doctor blade 45 is set to the same direction as the long-side direction of the thin wire electrode 5a, in the printing mask, the long-side direction corresponding to the opening of the bus bar electrode and the doctor blade The long side direction of the lower end will change Into parallel. Therefore, when the squeegee is moved on the printing mask, a part of the squeegee will fall into the opening corresponding to the bus bar electrode, and the bus bar in the electrode material paste printed from the opening to the printing surface The thickness of the central region in the width direction of the electrode will be greatly reduced.

On the other hand, in the printing mask 41, when the moving direction of the doctor blade 45 on the printing mask 41 is set to the same direction as the longitudinal direction of the first opening 46, the silver paste 31 is printed The lower end of the blade 45 is located in the longitudinal direction of the lower end of the blade 45 when passing through the area corresponding to the light-receiving surface-side collector electrode 5b (not shown) in the opening 44 The upper surface 41a of the printing mask between the adjacent second openings 47 is held. Therefore, the squeegee 45 does not fall into the area corresponding to the light-receiving surface-side collector electrode 5b in the opening 44. Therefore, the collector electrode 5b on the light-receiving surface side in the first embodiment can be formed at the same height as the thin wire electrode 5a.

Of course, the printing state will vary depending on the design value of the opening width, the type of electrode material paste, and the printing conditions, but for the reasons described above, in the solar cell 1, the height of the thin-line electrode and the solar In the case of a solar battery cell in which the thin wire electrodes 5a of the battery cell 1 are the same and are connected to the continuous general bus bar electrodes of all the thin wire electrodes, the tab wire connection portion 5c can be formed with a height higher than that of the general bus bar electrodes. That is, it is possible to form the tab wire connection portion 5c having a thickness thicker than that of a general bus bar electrode.

Then, in step S70, by firing the paste printed on the p-type polycrystalline silicon substrate, the thin wire electrode 5a as the light receiving surface side electrode 5, the tab wire connecting portion 5c, and the light receiving surface side current collection can be obtained The electrode 5b, the back aluminum electrode 7 and the back bus electrode 8 as the back electrode 9. In this firing step, the light-receiving surface-side electrode 5 fires through the anti-reflection film 4 belonging to the insulating film to make conduction with the n-type impurity diffusion layer 3. In addition, the area directly under the back surface aluminum electrode 7 in the n-type impurity diffusion layer 3 formed on the back surface side of the p-type polycrystalline silicon substrate is changed to the p+ layer 10 by aluminum diffusion.

By performing the above steps, the solar cell 1 of the first embodiment shown in FIGS. 1 to 3 is produced. In addition, the paste belonging to the electrode material may be arranged The order is replaced by the light-receiving surface side and the back surface side.

The above-mentioned solar cell 1 is provided with the light-receiving surface-side collector electrode 5 b and the tab wire connecting portion 5 c on the light-receiving surface-side electrode 5, and the tab wire 21 is welded to the light-receiving surface-side electrode 5 on the light-receiving surface side collector The electric electrode 5b and the tab wire connecting portion 5c. Here, the light-receiving surface-side collector electrode 5b can secure a wide bonding area with the tab wire 21, and thus can achieve a practical level of joint strength without peeling off the tab wire 21.

In addition, the light-receiving-surface-side electrode 5 is not formed with a tab wire connection area, that is, the thin-line electrode 5 a to which the light-receiving-surface current-collecting electrode 5 b is not connected is connected to the tab wire 21. In the region of FIG. 1, a tab wire connecting portion 5c is formed. In addition, the width X2 of the tab wire connection portion is set to be wider than the width X1 of the thin wire electrode. Therefore, in the area where the thin wire electrode 5a not connected to the light-receiving surface-side collector electrode 5b is connected to the tab wire 21, the tab wire 21 is directly welded to the one where the tab wire connecting portion 5c is not provided, compared to simply welding the tab wire 21 In the case of the thin wire electrode 5a, the area where the tab wire 21 and the thin wire electrode 5a are to be welded can be ensured to be wide. Therefore, when the tab wire 21 is welded to the light-receiving surface-side electrode 5, a practical level of joint strength can be obtained between the thin wire electrode 5 a and the tab wire 21 without peeling of the tab wire 21.

In addition, the shape of the tab wire connecting portion 5c is rectangular, so that the joining area with the tab wire 21 by welding can be ensured to be wide. For example, by forming the length Y1 of the tab wire connecting portion to be the same width as the width of the tab wire 21, and the width X2 of the tab wire connecting portion to 200 μm, it is sufficient At a practical level that does not cause obstacles in the solar battery module in which a plurality of solar battery cells 1 are connected by the tab wire 21, the bonding strength of the thin wire electrode 5a and the tab wire 21 is ensured.

In addition, the solar battery cell 1 includes the light-receiving surface-side collector electrode 5b intermittently arranged in the second direction, so it can be reduced compared to the case of forming a continuous general bus bar electrode connected to all the thin wire electrodes 5a The amount of silver used to form the bus bar electrode. Compared to a solar battery cell that does not have a tab wire connection portion 5c, the solar battery cell 1 will increase the use of silver as an electrode material The amount of increase corresponds to: the increase in the width of the tab wire connecting portion 5c from the width of other regions in the thin wire electrode 5a; and the height of the light collecting surface side collector electrode 5b, which will become more continuous The height of the bus bar electrode is higher and the height of the thin wire electrode 5a is equal. However, in the solar battery cell 1, the collector electrode 5 b on the light-receiving surface side is arranged intermittently in the second direction, which greatly reduces the amount of silver used. Therefore, compared with the case where a continuous general bus bar electrode is provided, the solar battery cell 1 can greatly reduce the light receiving surface side electrode 5 by adjusting the length of the light receiving surface side collector electrode 5b in the second direction The amount of silver used.

That is, in the area where the thin wire electrode 5a not connected to the light-receiving surface-side collector electrode 5b and the tab wire 21 are to be connected, the solar cell 1 expands the width of the thin wire electrode 5a and the area after the connection The tab wire connecting portion 5c is used as a connecting portion of the tab wire 21 to which the tab wire 21 is to be soldered. By this, in the area where the thin wire electrode 5a not connected to the light-receiving surface-side collector electrode 5b and the tab wire 21 are to be connected, compared with the provision of a continuous general bus bar electrode connected to all the thin wire electrodes 5a In the case of the solar cell unit 1, the area of the area where the tab wire 21 is to be soldered can be greatly reduced. Therefore, the solar battery cell 1 can greatly reduce the amount of silver used in the light-receiving surface-side electrode 5 while soldering the tab wire 21 to the light-receiving surface-side electrode 5, and it can be used at a practical level without hindrance in the solar battery module Next, the bonding strength of the tab wire 21 is ensured.

For example, the opening width X1a corresponding to the width X1 of the thin wire electrode in the printing mask 41 on which the thin wire electrode 5a is to be printed is set to a range of 20 μm or more and 50 μm or less, and only the width X2 of the connection part of the tab wire corresponds to The opening width X2a is set to a range of 100 μm or more and 700 μm or less. In this case, the electrode height of the thin wire electrode 5a including the tab wire connection portion 5c can be set to 15 μm.

In addition, even if, for example, the opening width X1a corresponding to the width X1 of the thin wire electrode in the printing mask 41 is changed from the range of 20 μm or more and 50 μm or less to the range of 50 μm or more and 100 μm or less, the splicing line may be included The thin wire electrode 5a of the connection portion 5c is formed to a thickness of 15 μm or more.

In this way, even when the opening width X2a corresponding to the width X2 of the tab wire connecting portion in the printing mask 41 is set to 700 μm, the height of the thin wire electrode 5a including the tab wire connecting portion 5c can be formed to be more equipped The height of the bus bar electrode when connected to the continuous general bus bar electrodes of all the thin wire electrodes 5a is higher. Therefore, in the solar battery cell 1, the contact area of the tab wire 21 and the light-receiving surface-side electrode 5 is reduced compared to the case where the continuous general bus bar electrode connected to all the thin wire electrodes 5a is provided, but by The thickening of the tab wire connecting portion 5c connected to the tab wire 21 can compensate the average adhesive strength per unit area of the area connected to the tab wire 21. This utilizes the bonding strength between the electrode and the tab wire by welding, which has a correlation with the thickness of the electrode, and the thickness of the electrode is advantageous from the viewpoint of bonding strength.

In addition, the width of the collector electrode 5b on the light-receiving surface side may be extremely thinned to, for example, 100 μm with respect to the width of the normal collector electrode of 1 mm or more and 2 mm or less. As a result, the amount of silver used in the light-receiving surface-side electrode 5 can be greatly reduced. Even when the collector electrode 5b on the light-receiving surface side is removed, the tab wire 21 can be connected to the solar battery cell 1. However, in evaluating the output characteristics of the solar battery cell 1, there may be a case where a current collecting electrode is required. For example, by providing the light-receiving surface-side collector electrode 5b with a width of 100 μm in the solar battery cell 1, the amount of electrode material used in the light-receiving surface-side electrode 5 can be reduced, and the output characteristics of the solar battery cell 1 can be measured.

Next, another example of the shape of the tab wire connecting portion 5c will be described. Fig. 11 is a plan view of another solar battery cell 51 according to Embodiment 1 of the present invention viewed from the light-receiving surface side. Fig. 12 is an enlarged view of a main part of an enlarged display of the thin-line electrode 5a of another solar battery cell 51 according to Embodiment 1 of the present invention. Fig. 13 is a plan view of the state where the tab wire 21 is connected to the thin-line electrode 5a of another solar battery cell 51 according to Embodiment 1 of the present invention when viewed from the light-receiving surface side. As shown in FIG. 11 and FIG. 12, in the other solar battery cell 51, the shape of the tab wire connecting portion 5 c in the in-plane direction of the other solar battery cell 51 is set to a rhombus. Since the other solar battery cell 51 includes the tab wire connection portion 5c, it has the same effect as the solar battery cell 1. In addition, the other solar battery unit 51 is formed by connecting the tab wire connecting portion 5c The shape is set to a rhombic shape, thereby obtaining the effect that the connection area between the connection line 21 and the connection line 5c of the connection line 5c can be ensured to be wider when the connection line 21 is shifted in the longitudinal direction of the thin line electrode 5a.

The width of the tab wire connecting portion 5c in the longitudinal direction of the thin wire electrode 5a, that is, the length Y1 of the tab wire connecting portion and the rectangular tab wire connecting portion 5c and the diamond tab wire connecting portion are equal 5c. Compare the connection area between the tab wire 21 and the tab wire connecting portion 5c. The length Y1 of the tab wire connecting portion of the diamond-shaped tab wire connecting portion 5c corresponds to the Y direction in the diamond-shaped tab wire connecting portion 5c, that is, the length of the diagonal line in the first direction. At this time, since the length Y1 of the tab wire connecting portion is equal to the area, the width X2 of the tab wire connecting portion of the diamond tab wire connecting portion 5c will become the tab wire connecting of the rectangular tab wire connecting portion 5c The width of the part X2 is twice. The width X2 of the tab wire connecting portion of the diamond-shaped tab wire connecting portion 5c corresponds to the X direction in the diamond-shaped tab wire connecting portion 5c, that is, the length of the diagonal line in the second direction. Now consider the case where the tab wire 21 deviates from the proper arrangement position on the tab wire connecting portion 5c in the first direction. The width of the tab wire 21 is the same as the length Y1 of the tab wire connecting portion of the tab wire 21 and the tab wire connecting portion 5c. When the splicing wire 21 is shifted to the position of half of the splicing wire connecting portion 5c, the splicing wire 21 and the splicing wire connecting portion 5c are formed between the rectangular splicing wire connecting portion 5c and the diamond-shaped splicing wire connecting portion 5c. The area of the connected area will become the same. If the offset of the tab wire 21 from the proper arrangement position on the tab wire connecting portion 5c is less than half of the tab wire connecting portion 5c, the area of the connecting area of the tab wire 21 and the tab wire connecting portion 5c, The connection part 5c of the diamond-shaped tab wire becomes larger.

Fig. 14 is a plan view of another solar battery cell 52 according to Embodiment 1 of the present invention viewed from the light-receiving surface side. Fig. 15 is an enlarged view of a main part showing an enlarged display of the thin-line electrode 5a of another solar battery cell 52 according to Embodiment 1 of the present invention. Fig. 16 is a plan view of the state where the tab wire 21 is connected to the thin-line electrode 5a of another solar battery cell 52 according to Embodiment 1 of the present invention when viewed from the light-receiving surface side. As shown in FIGS. 14 and 15, in the other solar battery cell 52, the shape of the tab wire connecting portion 5 c in the in-plane direction of the other solar battery cell 52 is set to be triangular. Since the other solar battery cell 52 is provided with the tab wire connection portion 5c, it has the same effect as the solar battery cell 1. In addition, another too By setting the shape of the tab wire connecting portion 5c to a triangle, the anode battery cell 52 can obtain an effect that the electrode pattern of the tab wire connecting portion 5c becomes asymmetric, and the orientation of the solar battery cell 1 can be easily recognized .

As described above, the solar battery cell 1 of the first embodiment includes the light-receiving surface-side collector electrode 5b intermittently provided in the second direction, that is, the light-receiving surface-side collector provided locally in the connection area of the tab wire Electrode 5b. Therefore, the solar cell 1 can reduce the amount of silver used to form the bus bar electrode compared to the case where the continuous general bus bar electrode connected to all the thin wire electrodes 5a.

In addition, in the solar battery cell 1, by adjusting the area of the light-receiving surface-side collector electrode 5 b intermittently arranged in the second direction, the light-receiving surface-side electrode 5 on the light-receiving surface side of the solar battery cell 1 can be changed The formed coverage is set to one-half or less when there is a continuous general bus bar electrode connected to all the thin wire electrodes 5a, and the amount of silver used in the light-receiving side electrode 5 can be reduced. Furthermore, by setting the width X2 of the tab wire connection portion to be half or less of the arrangement pitch X4 of the thin wire electrodes in the second direction, the tab wire connection area where the light-receiving surface-side collector electrode 5b is not formed can be formed The area of the light-receiving surface-side electrode 5 is set to half or less, and the amount of silver used can be greatly reduced.

For example, suppose that there is no bus bar electrode, the interval between the adjacent thin wire electrode 5a and the thin wire electrode 5a is 1.5 mm, and the tab wire connecting portion 5c is rectangular. At this time, the volume of the electrode of the bus bar electrode and the tab wire connection portion 5c is compared. It is assumed that the width of the tab line 21 is 1.0 mm. In the case of a general solar cell, when the height of the bus bar electrode is assumed to be 10 μm, the volume of the bus bar electrode between the thin wire electrodes 5a in the second direction becomes width × length × height = 1.0 mm × 1.5mm×10μm=0.015mm ³ .

Next, in the form of the light-receiving surface-side electrode 5 of the solar battery cell 1 of the first embodiment, the volume of the tab wire connecting portion 5c is calculated. It is assumed that the electrode width of the tab wire connecting portion 5c is set to 700 μm so as to be 1/2 or less of the distance between the thin wire electrodes 5a in the second direction, and the height is set to 20 μm. At this time, it becomes width × length × height = 1.0 mm × 700 μm × 20 μm = 0.014 mm ³ . Even if it is assumed that the height of the thin wire electrode 5a is doubled, as long as the width of the tab wire connecting portion 5c is equal to or less than half the distance between the thin wire electrodes 5a in the second direction, silver used for the light-receiving surface-side electrode 5 can be expected The effect of reducing the amount of use.

On the other hand, with regard to the bonding strength of the tab wire connection region where the light-receiving surface-side collector electrode 5b is not formed, in the solar cell 1, the tab wire connection portion 5c of which the width is widened in the thin wire electrode 5a The part is adhered to the tab line 21 by welding. Therefore, even if the solar cell unit 1 is, for example, a tab wire connecting portion 5c having a rectangular shape with a width of 200 μm, the bonding strength with the tab wire 21 can be ensured at a practical level where there is no obstacle in the solar cell module . However, the subsequent strength of course also depends on the electrode paste material, the material of the tab wire, and the welding conditions.

That is, the solar battery cell 1 can greatly reduce the amount of silver used for the collector electrode by providing a tab wire connection area where the collector electrode 5b on the light-receiving surface side does not exist, and can also collect on the side where there is no light-receiving surface. In the connection area of the tab wire of the electric electrode 5b, only the portion joined to the tab wire 21 is increased in width and area, so that the bonding strength of the thin wire electrode 5a and the tab wire 21 is improved.

In addition, the tab wire connection portion 5c does not necessarily need to be provided in all the thin wire electrodes 5a not connected to the light-receiving surface-side collector electrode 5b, but may also be provided in one of the thin wire electrodes 5a not connected to the light-receiving surface-side collector electrode 5b. 'S thin wire electrode 5a. Fig. 17 is a plan view of another solar battery cell 53 according to Embodiment 1 of the present invention viewed from the light-receiving surface side.

As shown in FIG. 17, the other solar battery unit 53 has three thin-line electrodes 5a between the light-receiving surface-side collector electrode 5b and the light-receiving surface-side collector electrode 5b in the second direction, and only at the center 1 The thin wire electrode 5a is provided with a tab wire connecting portion 5c. In the thin wire electrode 5a that is not connected to the light-receiving surface-side collector electrode 5b, the use of silver in the light-receiving surface-side electrode 5 can be further reduced by providing the thin wire electrode 5a that does not include the tab wire connection portion 5c.

The thin wire electrode 5a adjacent to the thin wire electrode 5a not provided with the tab wire connecting portion 5c among the thin wire electrodes 5a not connected to the light-receiving surface side collector electrode 5b is formed with a tab wire connecting portion 5c. In addition, the thin wire electrode 5a which is not connected to the light collecting surface side collector electrode 5b is not provided with a tab wire connection The other thin wire electrode 5a adjacent to the thin wire electrode 5a of the portion 5c is formed with a light-receiving surface-side collector electrode 5b. When the tab wire 21 is welded to the light-receiving surface side electrode 5, the thin wire electrode 5a without the tab wire connecting portion 5c has ensured the bonding strength between the adjacent thin wire electrode 5a and the tab wire 21, thus preventing the tab Stripping of line 21.

At this time, since there is also a thin wire electrode 5a that does not have a tab wire connecting portion 5c, the width X2 of the tab wire connecting portion may also be less than half of the arrangement pitch X4 of the thin wire electrode, but on the light-receiving surface side can be expected The width of the amount of silver used in the electrode 5 can be reduced to a certain extent.

In summary, the solar battery cell 1 of the first embodiment can achieve the bonding strength of the bonding wire 21 and the light-receiving surface-side electrode 5 electrically connecting the solar battery cells 1 to each other, and can reduce the electrode material. The effect of reducing the manufacturing cost of the solar cell unit 1 by using the amount.

Embodiment 2

In the tab line connection region where the light-receiving surface-side collector electrode 5b is not formed, a second collector electrode 5d that is thinner than the light-receiving surface-side collector electrode 5b that electrically connects the thin wire electrodes 5a to each other can be formed. Fig. 18 is a plan view of the solar battery cell 54 according to Embodiment 2 of the present invention viewed from the light-receiving surface side. The solar battery cell 54 of the second embodiment includes a second tab wire connecting portion 5c that extends in the second direction and is arranged at the same position in the first direction among the plurality of thin wire electrodes 5a to be electrically connected The current collecting electrode 5d is different from the solar battery cell 1 of the first embodiment in this point.

When the tab wire 21 is connected to the light-receiving surface-side electrode 5 of the solar cell 54, the tab wire connecting portion 5 c and the second collector electrode 5 d are welded to the tab wire 21. Here, in the solar battery cell 54 of the second embodiment, the width of the second collector electrode 5d is greatly thinned to 100 μm. On the other hand, as in the solar cell 1 of the first embodiment, the tab wire connection portion 5c welded to the tab wire 21 is provided on the thin wire electrode 5a, and the thin wire not connected to the light-receiving surface-side collector electrode 5b is provided The area where the electrode 5a and the tab wire 21 are to be welded is ensured to be wide. Thereby, in the solar battery cell 54, the same effect as the solar battery cell 1 of Embodiment 1 can be obtained.

In addition, the second collector electrode 5d in the solar battery cell 54 has a thin wire electrode The function of 5a is to concentrate current, but the main function is to electrically connect the thin wire electrodes 5a to each other. The solar battery cell 54 electrically connects the plurality of tab wire connecting portions 5c arranged in the second direction to each other, and electrically connects the thin wire electrodes 5a to each other. By forming the second collector electrode 5d first, when the thin wire electrode 5a is disconnected, the resistance loss caused by the concentration of the carrier on the other thin wire electrode 5a can be alleviated. The second collector electrode 5d is formed simultaneously with the thin wire electrode 5a and the like in steps S60 and S70.

In addition, the width of the second current collector electrode 5d is preferably within a range of 30 μm or more and 300 μm or less. When the width of the second collector electrode 5d is less than 30 μm, there is a problem that it is difficult to form it by screen printing and the second collector electrode 5d is disconnected. When the width of the second collector electrode 5d is larger than 300 μm, the amount of electrode used in the second collector electrode 5d increases, and the effect of reducing the amount of silver used in the light-receiving side electrode 5 becomes smaller. In addition, since the second collector electrode 5d is formed by screen printing, a slight width variation occurs depending on the part. Therefore, the width of the second collector electrode 5d is preferably within a range of an average value of 30 μm or more and 300 μm or less.

FIG. 19 is a plan view of another solar battery unit 55 according to Embodiment 2 of the present invention viewed from the light-receiving surface side. The other solar battery cell 55 is a modification of the solar battery cell 54 of the second embodiment, and like the solar battery cell 54 is provided with extending in the second direction, and is arranged in the first direction among the plurality of thin wire electrodes 5a. The plurality of tab wire connecting portions 5c at the position are electrically connected to the second collector electrode 5d. In addition, in the other solar battery cell 55, the thin wire electrode 5a is not formed in the region surrounded by the light-receiving surface-side collector electrode 5b and the second collector electrode 5d belonging to the first collector electrode.

In the other solar battery cell 55, the plurality of tab wire connecting portions 5c arranged in the second direction are electrically connected to each other through the second collector electrode 5d in the same manner as the solar battery cell 54. Therefore, as shown in FIG. 19, the thin wire electrode 5a may not be formed in the region surrounded by the light-receiving surface-side collector electrode 5b and the second collector electrode 5d belonging to the first collector electrode. By removing the thin-line electrode 5a in the region surrounded by the light-receiving surface-side collector electrode 5b and the second current-collecting electrode 5d belonging to the first collector electrode, the amount of silver used in the light-receiving surface electrode 5 can be further reduced.

When the tab wire 21 is connected to the light-receiving surface-side electrode 5 of the other solar battery cell 55, the light-receiving surface-side collector electrode 5 b and the tab wire connecting portion 5 c and the second collector electrode 5 d are welded to the tab wire 21. Here, in another solar battery cell 55, the width of the second collector electrode 5d is greatly thinned to 100 μm. On the other hand, as in the solar battery cell 1 of the first embodiment, the tab wire connecting portion 5c to be welded to the tab wire 21 is provided on the thin wire electrode 5a, and the thin wire not connected to the light collecting surface side collector electrode 5b The area where the electrode 5a and the tab wire 21 are to be welded is ensured to be wide.

In addition, the thin wire electrode 5a that is not connected to the light-receiving surface-side collector electrode 5b and does not include the tab wire connection portion 5c is connected to the second collector electrode 5d. When the tab wire 21 is welded to the light-receiving surface-side electrode 5, the thin wire electrode 5a that is not connected to the light-receiving surface-side collector electrode 5b and does not have the tab wire connecting portion 5c is connected to the second collector electrode that has been connected 5d and the tab wire 21, and the bonding strength between the thin wire electrode 5a adjacent to the light-receiving surface-side collector electrode 5b and the tab wire 21 is ensured, so the tab wire 21 is prevented from being peeled off. Therefore, in the other solar battery cell 55, the same effect as the solar battery cell 1 of the first embodiment can be obtained.

Embodiment 3

In the third embodiment, the measurement of the output characteristics of the solar cell 1 described above will be described. The measurement of the current-voltage characteristic, which is the output characteristic of the solar cell unit, that is, the IV measurement, can be performed using the 4-terminal method. The current collecting electrode of the light-receiving side electrode is also responsible for the current terminal for measuring the current connected to the measuring device that measures the output characteristics of the solar cell and the measuring device when measuring the current-voltage characteristics. The role of the external terminal that the voltage terminal for voltage measurement contacts. Here, when the resistance between the current terminal and the voltage terminal is high, the voltage drop in this area will have an adverse effect on the IV measurement, so care needs to be taken.

The IV measurement of the solar battery cell 1 is performed using a 4-terminal method in which the current and voltage generated in the solar battery cell 1 are measured at each terminal. When the IV measurement of the solar battery cell is performed by the 2-terminal method of measuring current and voltage with the same terminal, the measured voltage includes current flowing at the terminal The voltage generated by the contact between the solar cell and the solar cell unit drops. Therefore, when the IV measurement of the solar battery cell is performed by the 2-terminal method, a voltage different from the surface of the solar battery cell must be measured, and an error may occur in the measured voltage. On the other hand, in the 4-terminal method, a voltage terminal and a current terminal are distinguished, and a dedicated terminal is used for each of the voltage terminal and the current terminal. Due to this, current does not flow through the voltage terminal, so that the voltage drop at the contact resistance portion described above can be avoided. Here, in the 4-terminal method, the current and voltage measurement locations must be the same. However, when, for example, the distance between the current terminal and the voltage terminal is separated, or when the resistance between the current terminal and the voltage terminal is high, a voltage drop occurs between the voltage terminal and the current terminal, which may cause erroneous measurement .

In the solar battery cell 1 of the first embodiment described above, the current terminal for current measurement and the voltage terminal for voltage measurement are brought into contact with the tab wire connection portion 5c to perform IV measurement. In general, since the width of the thin wire electrode is set to about 100 μm and is extremely thin, it is difficult to make the terminal contact the thin wire electrode. However, in the solar battery cell 1, the tab wire connection portion 5c is enlarged to a width of, for example, 2 mm. As a result, when the IV measurement is performed in the solar battery cell 1, it is easy to make the terminal contact the thin wire electrode.

FIG. 20 is a cross-sectional view showing a state where the current terminal 61 and the voltage terminal 62 are in contact with the tab wire connection portion 5c of the solar cell 1 in Embodiment 3 of the present invention, and is a cross-sectional view along the second direction. In order to perform IV measurement using the tab wire connecting portion 5c, as shown in FIG. 20, the tab wire connecting portion 5c must be present in the area from the end of the current terminal 61 to the end of the voltage terminal 62. This is because the voltage drop in the tab line connecting portion 5c affects the measurement accuracy, and because the tab line connecting portion 5c exists, the resistance is lower and the voltage drop is smaller.

In each tab wire connecting portion 5c, only one thin wire electrode 5a is connected. On the other hand, a plurality of thin-line electrodes 5a are connected to the light-receiving surface-side collector electrode 5b. In IV measurement, both the current terminal 61 and the voltage terminal 62 are brought into contact with one tab wire connection portion 5c. Therefore, between the current terminal 61 and the voltage terminal 62, there is a tab wire connecting portion 5c belonging to a silver electrode with a wide width, because a large voltage drop does not occur and it does not become a problem in IV measurement.

As for the number of the tab wire connecting portions 5c, since the voltage terminals are brought into contact with the tab wire connecting portions 5c, it is preferably set to two or more for the stability of measurement. In addition, the number of collector electrodes 5b on the light-receiving surface side is preferably the same as the number of the tab wire connection portions 5c, or more.

The configuration shown in the above embodiments is an example of the content of the present invention, and the techniques of the above embodiments may be combined with each other or other known technologies as long as they do not deviate from the scope of the gist of the present invention It can be omitted or changed part of the structure.

1‧‧‧Solar battery unit

2a‧‧‧ 1st side

2b‧‧‧ 2nd side

2c‧‧‧3rd side

2d‧‧‧4th side

4‧‧‧Anti-reflection film

5‧‧‧Receiving side electrode

5a‧‧‧fine wire electrode

5b‧‧‧collector electrode on the light-receiving side

5c‧‧‧Connecting part

5c1‧‧‧The first wire connection

5c2‧‧‧Second wire connection

5c3‧‧‧The third wire connection part

5c4‧‧‧Connecting part of the 4th wire

Claims (23)

A solar battery cell includes: a semiconductor substrate having a pn junction; a plurality of thin wire electrodes provided on one surface of the semiconductor substrate, extending toward a first direction of the in-plane directions of the semiconductor substrate, and The in-plane direction of the substrate intersects with the first direction and is arranged parallel to each other; and a plurality of first collector electrodes are provided on one surface of the semiconductor substrate and connect two or more adjacent thin-line electrodes adjacent to each other The second direction intersecting the first direction is dispersedly arranged; the plurality of thin-line electrodes have the thin-line electrode connected to the first collector electrode, and the thin-line electrode not connected to the first collector electrode; not connected to the aforementioned The thin wire electrode of the first collector electrode is at the same position as the first collector electrode in the first direction, and the width of the thin wire electrode is set to be wider than that of the other areas of the thin wire electrode It belongs to the connection part of the connection line of the area for connecting the connection line. A solar cell unit according to item 1 of the patent application, wherein the average width of the tab wire connection portion in the second direction is larger than the width of the thin wire electrode other than the tab wire connection portion, and is the second The range of the arrangement pitch of the aforementioned thin wire electrodes in the direction is one-half or less. For example, in the solar cell unit of claim 1, the shape of the connection portion of the tab wire in the surface of the solar cell unit is rectangular. For example, in the solar cell unit of claim 2, the shape of the connection portion of the tab wire in the surface of the solar cell unit is rectangular. For example, in the solar cell unit of claim 1, the shape of the tab wire connection portion in the plane of the solar cell unit is triangular. For example, in the solar cell unit of claim 2, the shape of the tab wire connection portion in the plane of the solar cell unit is triangular. For example, in the solar cell unit of claim 1, the shape of the connection part of the tab wire in the plane of the solar cell unit is a rhombus. For example, in the solar cell unit of claim 2, the shape of the connection part of the tab wire in the plane of the solar cell unit is a rhombus. A solar battery cell according to any one of claims 1 to 8 has a second collector electrode that extends in the second direction and is arranged in the plurality of thin-line electrodes A plurality of the tab wire connecting portions at the same position in the first direction are electrically connected. For example, in the solar battery cell of claim 9, the width of the second collector electrode is in the range of 30 μm or more and 300 μm or less. For example, the solar cell unit of item 10 of the patent application includes a plurality of the aforementioned second collector electrodes. A method for manufacturing a solar battery cell includes: a first step of forming a second conductivity type impurity diffusion layer on one side of a first conductivity type semiconductor substrate; a second step of forming a surface of the semiconductor substrate A plurality of thin wire electrodes and a first collector electrode, the plurality of thin wire electrodes extending toward the first direction of the in-plane direction of the semiconductor substrate and intersecting the first direction in the in-plane direction of the semiconductor substrate The two directions are arranged in parallel, and the first collector electrode is connected to the two or more adjacent thin wire electrodes and is distributed in the second direction; in the second step, it is connected to the first collector The aforementioned thin wire electrode of the electrode, and The thin wire electrode connected to the first collector electrode, and the width of the thin wire electrode is set to be wider than other areas in the thin wire electrode, and belongs to the tab wire connecting portion of the area for connecting the tab wire, It is formed at the same position as the first collector electrode in the first direction of the thin wire electrode not connected to the first collector electrode. A method for manufacturing a solar battery cell according to claim 12 of the patent application, wherein the average width of the tab wire connection portion in the second direction is larger than the width of the thin wire electrode other than the tab wire connection portion, and It is a range of one-half or less of the arrangement pitch of the thin-line electrodes in the second direction. For example, in the method of manufacturing a solar cell according to claim 12, the shape of the connection portion of the tab wire in the surface of the solar cell is rectangular. For example, in the method of manufacturing a solar battery cell according to claim 13, the shape of the connection portion of the tab wire in the surface of the solar battery cell is rectangular. For example, in the method of manufacturing a solar cell according to claim 12, the shape of the connection portion of the tab wire in the plane of the solar cell is triangular. For example, in the method of manufacturing a solar battery cell according to claim 13, the shape of the tab wire connection portion in the surface of the solar battery cell is triangular. For example, in the method of manufacturing a solar cell according to claim 12, the shape of the connection portion of the tab wire in the plane of the solar cell is a rhombus. For example, in the method of manufacturing a solar battery cell according to item 13 of the patent application, the shape of the connection portion of the tab wire in the surface of the solar battery cell is a rhombus. As in the method of manufacturing a solar battery cell according to any one of claims 12 to 19, in the second step, a second collector electrode is formed, and the second collector electrode extends toward the second direction Extend, and electrically connect the plurality of tab wire connecting portions arranged at the same position in the first direction among the plurality of thin wire electrodes. For example, in the method of manufacturing a solar battery cell according to item 20 of the patent application, the width of the second collector electrode is within a range of 30 μm or more and 300 μm or less. For example, the method for manufacturing a solar cell according to item 21 of the patent application forms a plurality of the aforementioned second collector electrodes. For example, the method for manufacturing a solar battery cell according to any one of claims 12 to 22 includes connecting the terminal connected to the measuring device that measures the output characteristics of the solar battery cell to the aforementioned terminal after the second step The sheet-wire connection portion irradiates light of a predetermined amount of light on the light-receiving surface of the solar cell to measure the output characteristics of the solar cell.

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